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STRUCTURAL FIRE ENGINEERING RESEARCH AT THE UNIVERSITY OF SHEFFIELD Background Our structural fire engineering research started in 1985, when we were simply attempting to simulate the behaviour of isolated steel elements in furnace tests. We have used several software approaches since then, as the emphasis has shifted from beams and columns in isolation towards the performance of building structures as a whole. A massive stimulus was given to the whole subject by the fire tests on the full-scale composite frame at Cardington during the 1990s. Our early work was entirely analytical, and the main theme of our research remains in numerical modelling, but several of our major projects have had a substantial experimental component. This was initially done by going into partnership with other institutions with established experimental facilities and expertise, but in more recent work we have developed and used our own purpose-built facilities. The major recent themes have been the robustness of buildings, and the behaviour of thin composite floor slabs, in fire conditions. The academic members of the group are: Professor Ian Burgess Department of Civil & Structural Engineering Sir Frederick Mappin Building Mappin Street SHEFFIELD S1 3JD ian.burgess@sheffield.ac.uk (+44) (0) 114 22 25060 Dr Buick Davison Department of Civil & Structural Engineering Sir Frederick Mappin Building Mappin Street SHEFFIELD S1 3JD j.davison@sheffield.ac.uk (+44) (0) 114 22 25354 Dr Shan-Shan Huang Department of Civil & Structural Engineering Sir Frederick Mappin Building Mappin Street SHEFFIELD S1 3JD s.huang@sheffield.ac.uk (+44) (0) 114 22 25727 Professor Roger Plank Emeritus Professor of Architecture and Structural Engineering r.j.plank@sheffield.ac.uk Group website: http://www.fire-research.group.shef.ac.uk Vulcan Solutions website: http://www.vulcan-solutions.com 08 August 2016 Flowchart of projects Completed Work and the Research Workers Involved 1985-1988 Oyewole Olawale (PhD) **Steel column behaviour in fire** Analytical study of uniformly heated steel columns in fire, using finite strip and finite element (INSTAF) approaches. Ramberg-Osgood and bilinear stress-strain-temperature relationships were used. The finite strip analysis included the capability to detect local buckling of flanges. 1986-1989 Jamal El-Rimawi (PhD) **A secant approach to the analysis of steel beams in fire** Analytical study of steel beams with uniform and non-uniform temperature profiles. The 2-D secant stiffness software used Ramberg-Osgood material stress-strain-temperature characteristics, and comparisons were made with BS5950 Part 8 predictions and furnace tests. 1987-1990 Hassan Saab (PhD) **Finite element analysis of plane steel frames in fire** Development of an existing 2-D finite element inelastic spread-of-yield frame analysis (INSTAF) to include thermal distributions due to fire. Performed pilot studies on multi-storey rigid sway frames with local fires. 1987-1991 Sha’ari Abu (PhD) **Behaviour of steel frames in fire** Initial studies for subsequent frame analysis developments, including studies of the relevance of material unloading in zones of strain reversal. 1989-1992 Jamal El-Rimawi (SERC/SCI/BS project) **The influence of connection behaviour on the performance of steel beams in fire** Studies of behaviour of steel beams within multi-storey frames. The 2-D secant stiffness frame software (NARR) was developed to include temperature distributions, the effect of the semi-rigidity of simple beam-column connections, axial expansion of members and $P - \Delta$ effects. A range of studies was conducted on subframes and full plane frames, showing that even simple connections can enhance beam survival in fire, but that column stability must also be ensured. 1990-1994 Samer Najjar (PhD) **Three-dimensional finite element analysis of subframes at high temperatures** Development of the non-linear finite element frame analysis software previously used by Saab) to full 3-D capability for skeletal steel frames in fire. This was originally intended for use with column subframes, and so far has been used mainly to perform isolated column and subframe studies. It is capable of very high-deflection analysis of 3-D frames, including member buckling, but does not include semi-rigid connections. 1992-1995 Colin Bailey (PhD) **Further development of 3D frame analysis in fire** This was a major development from Najjar’s work, which increased the capabilities of the 3-D analysis to include semi-rigid connection characteristics, lateral-torsional buckling and plate elements to represent slab continuity. This was the software used for the EPSRC study referred to below. **The effects of strain reversal and fire spread on frame behaviour** Study of the behaviour of large multi-storey steel frames under the influence of fires restricted to a local compartment or storey, and of the residual effects and repairability of the structure after these have been extinguished. This is the first study that has considered natural rather than standard fire scenarios, and so the software has been developed to be capable of dealing with strain reversal due to cooling of the steelwork. 1993-1995 Cardington Frame Design Studies (El-Rimawi, Najjar, Bailey) **Cardington Frame Design Studies** As part of the design process for the fire tests on the 8-storey composite frame at Cardington a programme of predictive analyses was carried at several different levels of modelling. Various ways of rationalising the frame and the fire compartments have been used. Studies included the influence of test load level, the effect of column protection, load sharing via the secondary structure and connection stiffness, out-of-plane column failure, and slab continuity over supports. 1992-1996 Atilla Oven (PhD) **Partial interaction in composite beams in fire** Study of the behaviour of composite beams with partial interaction between the steel section and the concrete flange through the slip characteristics of the shear connectors. The software was developed to include partial interaction, and the influence on fire survival of various parameters such as beam span, load ratio and degree of interaction between the steel and concrete was examined. 1995-1997 **Windows-based User Interface for Vulcan** (Supported by British Steel plc) A highly interactive graphical user interface for Vulcan has been developed by consultants, which makes preparation of subframes for analysis less error-prone and much more efficient. On the output side the interface enables rapid selection and plotting of results generated by the program. 1993-1996 Lee Leston-Jones (PhD, supported by BRE and SERC) **Moment-rotation characteristics of end-plate connections in fire** A programme of experiments on typical semi-rigid connections used in steel and composite construction has been carried out at BRE Garston. The object of these was to determine how the moment-rotation characteristics of connections degrade with temperature rise; only a few indicative tests had previously been done. The study used mainly small UB and UC sections, and attempted to relate the high-temperature performance to existing data on ambient-temperature behaviour. general model for connection degradation at high temperatures has been postulated and a sensitivity study has been carried out on the influence of connections on fire survival of frames. 1995-1998 Paul Rose (PhD, supported by ECSC and British Steel) Modelling of the Cardington full-scale fire tests The six full-scale Cardington fire tests were studied in detail using Vulcan. In the post-test analyses, measured parameter values were used to refine the precision of the modelling, and sensitivity studies were carried out so that the relative importance to the behaviour of a range of aspects could be gauged. This modelling formed part of an integrated series of numerical analyses, together with complementary studies at TNO (Holland), CTICM (France) and British Steel Swinden Technology Centre. The shell elements used to model slabs were developed to a layered model as part of this project. 1995-1998 Paul Shepherd (PhD, supported by EPSRC) The effect of restraint on column performance in fire This was a study of the in-fire performance of restrained columns in multi-storey frame construction, carried out in collaboration with an experimental programme at the University of Ulster. The Ulster tests were analysed in detail, and a model of the mechanisms involved in axial restraint to column expansion in fire was developed. The latter gives some insight into the redistribution of internal forces which takes place in the building when fire-affected columns "collapse"; in most cases this redistribution prevents a real structural collapse. 1996-1998 Ahmed Allam (PhD funded by University of Sheffield Bursary) Tensile membrane action in slabs at high temperatures In full-scale fire tests carried out recently there has been a strong indication that concrete slabs survive to very high fire temperatures, maintaining the vertical compartmentation of a building, due to a self-equilibrating membrane action. This occurs at high deflections and represents the true ultimate condition in the fire Limit State. An improved slab formulation which will assist in the modelling of membrane action, was researched and partially implemented. 1996-1998 Neal Butterworth, (Research Assistant supported by EPSRC under ROPA) Fire protection systems for steel columns Innovative fire-protection systems for steel columns in multi-storey frame construction were evaluated for thermal and structural effectiveness. It is currently generally accepted that columns must be fire-protected, and this on-site process is both expensive and time-consuming. Systems which offer the prospect of prefabrication, cutting out the costly programme delays, were tested computationally first for thermal effectiveness and for structural fire survival. An MPhil has now been awarded. 1998 Vulcan Our finite element software, which had by now been developed to a massive extent from its origins in INSTAF, was re-named Vulcan in 1998 by the research group. This is not an acronym - Vulcan is the Roman god of fire and the forge, and his statue stands above Sheffield Town Hall, reflecting the city's long tradition of steelmaking and engineering. 1998-1999 Graham Knapp (MSc(Res) Student, funded by EPSRC) Design studies based on the Cardington tests The full-scale Cardington fire tests were used as a basis for the development of a more enlightened approach to the design of composite multi-storey structures than had previously been possible. The development of design documents for this Fire Engineered approach is envisaged as being phased to co-ordinate with numerical modelling over a wide parametric range. This project performed a series of studies to support the development of a "Level 1" design guide which was published by SCI in 2001. 1996-2000 Khalifa Al-Jabri (PhD, partially supported by BRE & DoE under Partners in Technology) Moment-rotation characteristics of steel and composite connections in fire This work extended the experimental programme started by Leston-Jones on the high-temperature properties of bolted steelwork connections, in a series of tests on connections typical of those used on the Cardington full-scale frame. These connect much larger beam and column sections than those previously tested, and provide an opportunity to test the connection modelling principles postulated by Leston-Jones. The properties themselves are being used in post-test Cardington studies, and these will provide a guide to the importance of connection characteristics to fire survival of frames. Initial studies were also made in the development of a component-based method of representing connections for fire resistance. 1996-1999 Young Wong (PhD, supported by Health & Safety Laboratories) Portal frames in fire This project studied the collapse behaviour in fire of industrial portal frame structures, commonly used for warehousing of highly inflammable organic substances which produce extremely toxic effluents on burning. In the course of the project portal frames were modelled numerically, and two series of fire tests were carried out at HSL Buxton. 1996-1999 Dr Zhaohui Huang, (Research Associate, supported by EPSRC) A new slab element for Vulcan The elevated-temperature concrete failure model originally implemented in Vulcan was rather crude in its assumptions, and there were some circumstances in which it provided an unreasonable representation of the slab behaviour. In this project a A new failure model for concrete floor slabs at elevated temperatures was developed, and this was implemented in conjunction with a layered slab element which allows thermal distributions within the slab to be represented and progressive cracking and crushing of the concrete to be modelled. Partial interaction at shear studs in composite construction has recently been included. The Cardington fire tests were used to validate these developments and a number of papers have been written. 1998-2001 Ahmed Allam (Research Assistant + PhD, supported by EPSRC) The effect of restraint on the behaviour of steel beams in fire This project, which involved collaboration with the University of Manchester, began in February 1998. It involved examination of the effects of in-plane restraint to the fire compartment by adjacent structure for steel-framed buildings using non-composite precast slabs, with an emphasis on the ultimate development of catenary action in the beam grillage. The work included furnace testing at Manchester and frame modelling at Sheffield. 1998-2000 Craig English (PhD) Risks to structural stability and life safety in fire This project compared the risks to life [pre-flashover] and the risks of structural failure [post flashover] in low-rise steel-framed office buildings when the alternative fire resistance options [60mins FR and 30mins FR + sprinkler] in Table A2 of Approved Document B are used. A risk comparison approach, as described in PD7 of BS 7974 was adopted. The study used statistical data, event trees and two separate risk models of the Monte Carlo type to calculate these risks. The findings demonstrated that unclad steel framed buildings which only have sprinkler protection provide a much higher level of life safety and structural fire safety than do structures which are designed simply for 60 minutes' fire resistance [the code recommendation] and that further trade-offs in fire safety measures should be given to increase the financial viability of this design option. 1998-2001 Spyros Spyrou (Research Assistant + PhD, funded by EPSRC) A component model for steel end-plate connections in fire This project included a programme of furnace tests to identify the degradation of characteristics of the most important parts of typical connections at elevated temperatures, together with detailed finite element studies. These were very successfully used to develop a Component Method to represent the behaviour of steel-to-steel connections at elevated temperature, following the principles used at ambient temperature in Eurocode 3 Annex J. This method allows the connection behaviour in rotation and in thrust to be combined easily in frame modelling. 1998-2002 Jun Cai (Research Student, funded by British Steel/SCI) A general beam-column element for Vulcan In the course of this project new elements were devised to represent general beam-column member cross-sections in the Vulcan software. These elements were necessary firstly to model reinforced concrete beams and later to represent cross-sections which are asymmetric, hollow, or contain different materials. They are segmented so that temperatures and material properties can vary as required in two dimensions. Studies were also conducted using these elements on the effect of push-out on the survival in fire of columns in multi-storey buildings during fires. 1999-2000 Dr Zhaohui Huang, (Research Associate, internal support) **A new shell element for Vulcan** In this six-month bridging project a new 9-noded layered flat-shell element with a geometrically non-linear formulation, which embodies the developments made to the previous 4-noded elements, was developed and introduced into the **Vulcan** software. This was validated wherever possible in a range of comparisons against analytical solutions, independent numerical modelling and test results. This has enabled modelling of the large-deflection behaviour of floor slabs in fire conditions, including both thermal buckling against restraint and tensile membrane action. 1999 Dr Antonio Claret de Gouveia (Visiting Scholar, University of Ouro Preto, Brazil) **Fire resistance of Brazilian steel sections** A finite element study was made of the behaviour in fire conditions of welded I-section beams, of the type produced by Brazilian steel manufacturers. The effects of high residual-stress patterns and of partial protection were the main themes of this work. 2000-2003 Dr Zhaohui Huang, (Research Associate, supported by EPSRC) **Geometrically non-linear analysis of 3-dimensional composite building behaviour in fire** The major objective of this project is to try to shift the basis of fire resistance design from its present dependence on standard fire testing of isolated members to the performance of real building structures in fire. It will investigate the ultimate integrity of fire compartments in multi-storey composite building frames by wholly (material and geometric) non-linear modelling. The project started in April 2000. 2000-2004 Seng-Kwan Choi (Research Student, funded by Metsec Building Products plc.) **Behaviour of long-span composite trusses in fire** In this project the fire resistance of lightweight long-span composite lattice girders was investigated. Such systems are very often used in the United States, to produce commercial multi-storey buildings with column-free beam spans of up to 20m. The systems have so far been rather neglected in the Britain, largely because of the traditional fire protection requirements necessary to achieve normal fire resistance ratings. A series of parametric studies were performed in this project, to identify the fire engineering design strategies necessary in order to make these systems perform to the expected standards when subjected to fires. The modelling was extended to the composite floor arrangement used in the World Trade Center twin towers in New York, in order to provide some insights about the likely floor system behaviour during the events of 11 September 2001. 2003-2004 Dr Paul Shepherd (Buro Happold) and Dr Zhaohui Huang (University of Sheffield) **Vulcan rewriting and re-validation** The structural modelling software Vulcan, developed for many years by the Group in Fortran code, has been completely rewritten in C++, with a completely integrated Windows graphical user interface. The new interface allows practical 3-dimensional subframes of composite buildings to be created very efficiently, including loading and thermal scenarios. It also allows input data and results to be viewed in perspective, with rendered member and slab surfaces, and results to be transferred directly to Excel for creation of reports. During 2005 this software was made commercially available to designers as a tool for performance-based fire engineering design of structures. A university spin-off company, Vulcan Solutions Ltd, was set up to handle this commercialisation. 2001-2004 Samantha Foster (Research Student, funded by EPSRC and Arup Fire) Tensile membrane action in concrete slabs A new fire-resistance design method for composite slabs, proposed by Professor Colin Bailey of Manchester University and embodied in a recent design document, is based on a simplified model of the enhancement to yield-line slab capacity which is caused by tensile membrane action at high deflections. In fire high deflections are acceptable provided that no structural collapse or loss of compartmentation occurs, so that fire spread beyond the compartment of origin is prevented. In this project the proposed method has been investigated with respect to its own formulation, in comparison with numerical modelling, and finally using a large number of experiments. A system was developed initially to carry out a large number of small-scale ambient-temperature experiments, which were not initially envisaged, during the first phase of the project, and the experimental system was developed to conduct loaded high-temperature tests at model-scale. At this scale it has been possible to perform large numbers of tests, which would have been prohibitively expensive at larger scale, and these can be used to test both the simplified method and advanced modelling approaches. The student was also able to perform modelling studies to rationalise the floor slab behaviour of the final (7th) full-scale fire test at Cardington, which was performed in January 2003. 2003-2007 Marwan Sarraj (Research Student, funded by EPSRC) Performance of fin-plate beam-column connections in fire This was a computational investigation of the behaviour and robustness of steel fin-plate joints in fire, under catenary tension together with high rotations. The modelling employed ABAQUS to produce very detailed finite element representations. These were very complex models using contact elements at the bolt/hole interface, and considerable problems with these were overcome in progressing to the stage where a complete connection behaviour could be modelled to very high distortions at ambient and elevated temperatures. It was possible, in collaboration with the Czech Technical University, Prague, to compare the model’s predictions with the results of two full-scale fire tests conducted in the Czech Republic. The results of the FE studies were also used as a basis for the development of a simplified component-based approach to be used in global modelling software for performance-based design where fin-plate connections are to be employed. 2003-2007 Florian Block (Research Student, funded by Buro Happold FEDRA) Component modelling of end-plate beam-column connections This project followed on from the work of Spyros Spyrou in identifying the degradation of characteristics of the most important components of typical connections at elevated temperatures. The work aimed to fill in important gaps in the list of components which have already been modelled, so that connections in full structural assemblies could be represented properly in numerical modelling. The effect of axial superstructure load on the behaviour of column-web behaviour in the compression zone of an end-plate connection was studied experimentally and analytically. As a final stage in the project a component-based formulation was developed for a steel beam-to-column finite element to be incorporated in global analysis of building structures in fire conditions. 2003-2007 Chaoming Yu (Research Student) **Fire resistance of bi-steel core-walls** This project’s focus was on the possibility of using bi-steel concrete-filled walls in the construction of highly robust fire-resistant service cores for use in medium- to high-rise multi-storey buildings. The temperature distributions generated in the concrete and steel cross-section were initially studied. In order to investigate the structural behaviour of the bi-steel cross-section under load and complex temperature distributions, it was necessary to formulate a new 3-dimensional brick element for the software Vulcan, and to implement it in the program code. General-purpose finite element packages had proved to be very fragile in analysing such problems, but the new brick element performed well. Some studies of the performance of bi-steel wall panels were conducted, and it is hoped to use the new element intensively in future projects investigating steel-concrete composite structural systems in fire conditions. 2004-2008 Xinmeng Yu (Research Student) **Development of a ribbed-slab element for structural fire modelling** Slabs are seen to perform a key role in enabling the survival of composite buildings in fire, and their behaviour forms the basis of performance-based structural fire engineering design strategies for such buildings. Previous treatments of ribbed slabs in Vulcan tended to neglect the temperature variations between the ribs and troughs. In this project a thermal model was developed for these areas, followed by the development of a slab element which reflects these temperature variations, as well as the changes of slab depth. This was followed by studies which investigated the sensitivity of slab behaviour to this and other effects such as concrete spalling. In the final phase of the project an advanced slab element was developed in which the occurrence and development of localised tension cracking was modelled directly. Since failure of slabs is more often associated with integrity failure than with structural collapse, this is an important development. It will be followed-up in subsequent projects in order to establish a method of routinely allowing localised cracking to be represented in performance-based design using global modelling of whole structures or large sub-structures. 2005-2008 Dr Hongxia Yu (Research Associate, funded by EPSRC) and Ying Hu (Project Research Student, funded by EPSRC) **Robustness of steel connections in fire** In the aftermath of the New York twin Towers disaster, robustness (avoidance of progressive collapse emanating from localised failures) has become a major issue in the development of performance-based approaches to structural fire engineering design. In multi-storey buildings failure of connections is one of the main potential sources of progressive collapse, as is already recognised in UK structural design codes for other limit states. The robustness in fire conditions of end-plate connections has been investigated in this project, in which we have collaborated with researchers at the University of Manchester. At both centres the investigation involved a mixture of experimental and analytical work. In the Sheffield work the focus was on high-temperature structural behaviour of components and assemblies under combinations of tying and shearing forces. A large number of connection tests to destruction under inclined forces have been performed, at temperatures up to 650°C, for four typical beam-column connection types. Modelling using Finite Element analysis has rationalised the test results, and this has subsequently been used to help with the development of simplified component characteristics, to be used in constructing component-based joint elements for global modelling which can feasibly be used in design. Several journal papers have been published; these can be found under Publications. The project’s photos and test data sheets can be downloaded from the Group’s website fire-research.group.shef.ac.uk/downloads/. The Manchester group initially focused on the thermal behaviour of connection elements under different heating regimes, and in the final phase performed structural subframe testing which will enable modelling which includes component-based connection simulation to be validated. 2005-2009 Ying Hu (Project Research Student, funded by EPSRC) Robustness of steel connections in fire: Flexible endplate joints Within the EPSRC project on Robustness of Steel Connections in Fire (see above) this sub-project concerned the failure of flexible (partial-depth) endplate joints under combinations of vertical and tying forces. 2005-09 Yuan Yuan Song (Research Student) Dynamic analysis of structures in fire The loss of stability of structural elements in a fire can cause dynamic effects, including successive impacts or progressive collapse scenarios such as those which were observed in the September 11 2001 twin towers collapses. Progressive collapse is clearly a subject which is in need of study under hazard loadings of all kinds. Alternatively, unstable behaviour may be capable of regaining stability after either small or large deformations have occurred; an example of this behaviour is the inversion of the roofs of pitched portal frames, which may lead either to collapse or to re-stabilisation depending on the details of the design, the column base conditions and the fire scenario. In order to analyse these situations it is clearly necessary to study structural behaviour dynamically, and in this project the prime objective has been to provide Vulcan with the capability to perform dynamic analysis as well as quasi-static high-deflection, high-temperature modelling. This has been applied to steel portal frames in fire, for which a UK design process based on rather arbitrary assumptions has been in existence for nearly 30 years. The new procedure has been used to develop a new simplified design approach to calculate the final collapse temperatures for portal frames in fire. 2004-2008 Anthony Abu (Research Student, part-funded by Corus Ltd) **Thermal and structural behaviour of concrete slabs at high temperatures** The work on tensile membrane action initiated by Samantha Foster is being taken further in this project, in which the behaviour of heated and loaded slabs will be studied in detail. In particular, the membrane stresses and cracking mechanisms caused by thermal gradients through the slab thickness, acting alone, will be studied before their combination with externally applied loads. If necessary, more model-scale testing can be done to complete the range of validation results. A detailed comparative study was made between a current simplified analytical/design method for tensile membrane action and modelling of composite slabs using Vulcan. This has highlighted particularly the structural failure case in which edge beams eventually fold, limiting the range within which tensile membrane action acts as the main load-bearing mechanism. 2005-2009 Shan Shan Huang (Dorothy Hodgkin Research Student, funded by Corus Group and EPSRC) **The effects of transient strain on the strength of concrete-filled columns in fire** Pre-compressed concrete has been observed to acquire a large amount of non-recoverable strain when it is heated, a creep-like effect which seems not to occur when heating precedes the application of compressive stress. The objective of this project was to assess how this phenomenon, and concrete creep of other types, affect the buckling resistance of concrete-filled hollow-section columns, as well as slender RC columns, in fire. A fundamental study of the mechanics of buckling of compression members affected by temperature spread and time-dependent straining was carried out, using the classic Shanley model of inelastic buckling as its basis. Both simplified and finite element models of buckling of columns have been developed, and studies of the effects of pre-compression on columns affected by fire heating have shown that transient strain has the capability to reduce buckling loads compared with those predicted by conventional approaches based only on the degradation of ambient-temperature material characteristics due to heating. 2008-11 Vui Yee Bernice Wong (Research Assistant, funded by EPSRC) **Performance of cellular composite floor beams under fire conditions** Despite the current popularity of long-span composite flooring systems, the current structural fire engineering design codes EC3/4 Part 1.2 and BS5950 Part 8 do not contain rules or guidance on the fire resistance of composite floors employing cellular steel beams. The purpose of this project was to investigate the performance and failure mechanisms of composite cellular floor beams at elevated temperatures, including the influences of both flexure and shear. Emphasis will also be placed on examining the development and influence of the additional compression forces caused by axial restraint to thermal expansion from adjacent structure when a beam is heated in a fire. The research was coordinated with a programme of physical model fire tests at Ulster University, which provided carefully monitored data. A configurable finite element model was developed to demonstrate the 3-dimensional behaviour of composite cellular beams, which was validated against the tests to ensure that all types of failure modes are predicted. An extensive parametric study was carried out, extending the scope of the research beyond the limits of the parameters used in the experimental work and investigating the influence of CB behaviour on membrane action of floor slabs in compartment fires. The project also developed a design methodology for such members in fire. 2008-12 Mariati Taib (Research Student, funded by Universiti Sains Malaysia) **The Performance in Fire of Framed Structures with Fin Plate Connections** The work of Sarraj in developing realistic FE models for fin plate connections in fire, also enabled the creation of a simple component-based model, allowing only horizontal bolt-hole distortions, for a fin plate connection, which was validated against purely rotational furnace tests by Leston-Jones. In order to make such models capable of dealing properly with the combinations of vertical and horizontal forces, together with high rotation, that are experienced by such connections at the ends of beams in real structural fire scenarios, the component-based approach is in need of major development. Although fin plate joints are generally considered as "simple" their behaviour when the steel is highly ductile is actually very complex compared with other types, including distortions at bolt-holes which are in completely different directions. This project has created an integrated component-based element for fin-plate connections which was implemented in the software **Vulcan**, including the influence of both vertical and horizontal forces at bolt rows, as well as unloading and cooling properties. 2009-12 Shan Shan Huang (Post-doctoral Research Associate, funded by the European Commission under RFCS) **COMPFIRE: Robustness of connections to composite columns in fire** This was a European-funded (RFCS) project in which we worked with teams at Manchester, Coimbra, Lulea and Prague, as well as Tata Steel Ltd. It concerned the behaviour and robustness in fire of practical connections between steel or composite beams and two types of composite column - concrete-filled hollow sections and partially-encased H-sections. Tests were carried out at various scales, accompanied by detailed FE modelling, and a component-based approach has been developed. The Sheffield group conducted a total of 20 tests, in a setup similar to that used for steel-to-steel connections by Yu, at ambient and elevated temperatures, on end-plate connections to partially encased H-columns and on reverse-channel connections to both square and circular concrete-filled hollow-section columns. Reverse-channel connections in particular showed a considerable degree of ductility both in rotation and in push-pull, which offers great potential for their use as robust connections in fire conditions. The tests were used mainly to develop connection component models to enable connection interaction to be modelled in whole-structure modelling. 2008-12 Rui Rui Sun (Research Student) **A dynamic analysis for structural robustness modelling in fire** This project forms a significant advance on the work done previously by Song in setting up a dynamic formulation to analyse steel portal frames beyond an initial loss of stability. In this case the emphasis was on developing a general capability to model alternately both the static and dynamic behaviour of steel, concrete and composite buildings during both local and global progressive collapse caused by fire The analysis is intended to follow the structural behaviour from static response through local failure of components. At each stage when an instability is caused by a local fracture the subsequent dynamic behaviour is modelled using an explicit scheme until re-stabilization occurs. This kind of model is necessary in order to determine whether progressive collapse ensues or a re-stabilised state occurs, and will thus allow fire engineering designs to be assessed for robustness. It has been used already with a component-based connection model to track a sequence of local failures leading to a final collapse. 2009-14 Yuan Tian (Research student, funded by Tata Steel Ltd) **Tensile membrane action in non-rectangular composite slab panels** The Bailey-BRE design method for composite rectangular slab panels in fire presents a simplified model of tensile membrane action (TMA), the strength enhancements it gives as a function of displacement, and integrity failure by tensile fracture of the slab at a limiting deflection. This project aims to investigate TMA in non-rectangular slab panels, which could directly allow the simplified method to be extended to such slabs, so that performance-based fire engineering design can be used for buildings with irregular column grids. The first task in the project was to implement general boundary conditions linking degrees of freedom of the system. This has been implemented in **Vulcan**, and now allows numerical analysis of panels with local rather than global boundary conditions, which may be necessary either because internal panels need to be subject to credible continuity conditions, or because slabs have non-orthogonal overall shapes. A complete simplified tensile membrane action method is given for triangular slabs at high deflections, and initial work has been done in developing a similar method for trapezoidal slab panels. 2009-16 Gang Dong (Research Assistant/research student, funded part-time by the European Commission under RFCS) **COMPFIRE: Robustness of connections to composite columns in fire** This project addresses one of the work packages of COMPFIRE, which is based on the creation of a general-purpose component-based representation of the connections to composite columns, partly using component characteristics which have been developed in previous projects (see Spyrou, Block, Yu, Hu), but also developing new components for the reverse-channel connection type. The objective has been to represent the column-face "connection" zone with an element which has two external nodes but can contain internally any number of rows of components with temperature-dependent properties including both force-reversal and failure. The principles developed are applicable to different connection types and to implementation in different software packages. Within COMPFIRE the component-based element has been informed by tests and detailed FE analysis, which have aided both its development and its validation. When implemented in the staticdynamic development (Sun) of Vulcan, this component-based element has been able to model the progressive collapse process due to the sequential fracture of bolt rows of connections as temperatures increase. Microstructural characterisation and performance of steels used in structural bolting assemblies in fire Bolted connections are key components which tie structural members together. When a steel structure is subjected to elevated temperatures during a fire the forces applied by highly deflected beam members must be transferred to adjacent cold members through the connection to avoid collapse. During a fire connections are subjected to both compressive and tensile axial forces due to thermal expansion and subsequent contraction of beam members during cooling. Connections are thus subjected to a complex combination of rotation, extension and shear bending and shear. These complex loading conditions, coupled with an insufficient understanding of the mechanical properties of bolts at elevated temperatures means that bolting assemblies can often be the weak link in structural frames in fire. Bolt failure in fire generally occurs as ductile necking in the bolt thread, thread stripping in the nut and bolt or shear failure through the bolt thread or shank. At ambient temperature, bolt failure is designed out; other more ductile modes of failure are designed to be critical, thus ensuring adequate ductility. Recent research has demonstrated that this is not the case in fire situations when the bolt becomes critical. In this project the performance in fire conditions of nuts and bolts will be investigated by looking at the effects of manufacturing processes on their microstructure and thus on the way this affects performance under normal and elevated-temperature conditions. Current Work and the Research Workers 2012- Mohammad Javaheriafif (Research student) Characterisation of the “slab” component for component-based connection elements at elevated temperatures This project aims to produce a simplified model of the behaviour of the component-zone which represents the continuing concrete slab and its reinforcement in modelling beam-column and beam-beam connections. This part of the connection clearly provides considerable stiffness to the connection which is important to its rotational behaviour in ambient-temperature semi-rigid design. However it is not yet established that its ductility is adequate to play a significant part in the robustness of composite buildings in fire. In later stages the problem of continuity of slabs beyond the immediate connection zone and their behaviour across beams on the column grid will be addressed. 2012- Guan Quan (Research student, funded by EPSRC & China Scholarship Council) Shear buckling in the vicinity of beam-column connections in fire The Cardington composite frame fire tests indicated that shear buckling of beams, as well as beam bottom flange buckling, in the vicinity of the beam-column joints, is very prevalent under fire conditions. These phenomena can have significant effects on both the force redistribution between the bolt rows at the face of the column and beam deflections at high temperatures. This research is currently aimed at investigating the local buckling behaviour in the vicinity of beam-column joints at elevated temperature. The behaviour being studied includes shear buckling of the beam, local buckling of the bottom flange of the beam and shear buckling of the column. Theoretical models will be created for the three buckling zones at elevated temperature. On this basis, three corresponding component-based models will be created and implemented in the software Vulcan, in order to study their influences on the behaviour of the whole structure, and particularly on its progressive collapse in fire. 2015- Fabien Quichaud (Research student) A kinematically consistent approach to analysis of tensile membrane action of composite floor slabs in fire A new kinematically consistent simplified method will be developed to model the enhancement of small-deflection capacity of composite slabs due to tensile membrane action (TMA) at high deflections. This will be used as the basis of an analytical method to assess the enhancement to the fire resistance of composite slabs with unprotected internal beams due to TMA. The analysis will take into account the different mechanisms through which a rectangular composite slab can fail, and its different modes of failure. The method needs to take into account different failure mechanisms, based on the slab geometry and characteristics, and also needs to include fracture of reinforcement, related to temperature distributions and deflection. The aim is to create a rational design procedure to define the fire resistance of slabs designed on a partially protected basis, under both the Integrity and Resistance criteria. Work so far has developed a basic theory for both the initial yield-line mechanism (“B”) and the subsequent large-deflection mechanism (“A”). Group Publications to Date 1988 1989 1990 1991 1992 1993 Internal Research Report 1994 1995 1996 **Internal Research Reports** **1997** **Internal Research Reports** **1998** **Internal Research Reports** **1999** Internal Research Reports 2000 Internal Research Reports 2001 2002 2003 2004 2005 **2006** 2007 164. Yu, H.X., Davison, J.B., Burgess, I.W. and Plank, R.J., 'Experimental Investigation of the 165. Song, Y.Y., Huang, Z., Burgess, I.W. and Plank, R.J., 'The Design of Pitched-Roof Steel 166. Huang, Z., Burgess, I.W. and Plank, R.J., 'Effects of Spalling on the Behaviour of Reinforced Concrete Structures in Fire', Fib Workshop: Fire Design of Concrete Structures - from Materials Modelling to Structural Performance, Coimbra, Portugal, November 2007. 167. Huang, S.S., Burgess, I.W., Huang, Z. and Plank, R.J., 'The Buckling of Slender Concrete and Concrete-Filled Columns in Fire', Fib Workshop: Fire Design of Concrete Structures - from Materials Modelling to Structural Performance, Coimbra, Portugal, November 2007. 168. Yu,X.M., Huang, Z., Burgess, I.W. and Plank, R.J., 'Modelling Localised Failure of Reinforced Concrete Slabs in Fire', Fib Workshop: Fire Design of Concrete Structures - from Materials Modelling to Structural Performance, Coimbra, Portugal, November 2007. 2008 170. Al-Jabri, K.S., Davison, J.B. and Burgess, I.W., 'Performance of Beam-to-Column Joints in 171. Choi, S.K., Burgess, I.W. and Plank, R.J., 'Performance in Fire of Long-Span Composite Steel Connections in Fire Using Explicit Dynamic Analysis', *J. Construct. Steel Research*, 173. Qian, Z.H., Tan, K.H. and Burgess, I.W., 'Behaviour of Steel Beam-to-Column Joints at Elevated Temperature: Experimental Investigation', *Acc. ASCE Journal of Structural 174. Huang, S.S., Burgess, I.W., Huang, Z. and Plank, R.I., 'Effect of Transient Thermal Strain on the Buckling of Slender Concrete and Concrete-Filled Columns in Fire', Proc. Structures in Fire Workshop, Singapore, pp594-605. 175. Hu, Y., Burgess, I.W., Davison, J.B. and Plank, R.J., 'Modelling of Flexible End Plate Connections in Fire Using Cohesive Elements', Proc. Structures in Fire Workshop, 176. Yu, H.X., Burgess, I.W. Davison, J.B., and Plank, R.J., 'Experimental Investigation of the Behaviour of Flush Endplate Connections in Fire', Proc. Structures in Fire Workshop, 177. Abu, A. K., Burgess, I.W. and Plank, R.J., 'Effects of Edge Support and Reinforcement Ratios on Slab Panel Failure in Fire', Proc. Structures in Fire Workshop, Singapore, pp380-391. 178. Song, Y.Y., Huang, Z., Burgess, I.W. and Plank, R.J., 'A New Design Method for Industrial 2009 2010 2011 2012 2013 2014 258. Quan, G., Huang, S.-S. and Burgess, I.W., 'Shear panel component in the vicinity of beam-column connections in fire', Structures in Fire conference, Shanghai, 2014. 2015 2016 Accepted for publication: Currently submitted: 287. Burgess, I.W., 'Yield-Line Plasticity and Tensile Membrane Action in Lightly-Reinforced Rectangular Concrete Slabs'.
Poetics and Polemics: The Politics of Patrick Kavanagh's "Spraying the Potatoes" Thomas B. O'Grady Follow this and additional works at: https://digitalcommons.colby.edu/cq Recommended Citation Colby Quarterly, Volume 31, no.4, December 1995, p.242-252 Poetics and Polemics: The Politics of Patrick Kavanagh’s "Spraying the Potatoes" by THOMAS B. O'GRADY In many respects, "Spraying the Potatoes," a relatively early lyric first collected in A Soul for Sale (1947), epitomizes both the thematic vision and the poetic technique of Patrick Kavanagh. Thematically, the poem obviously reflects Kavanagh's preoccupation with rural subject matter throughout his career. Focusing on a crucial (if rarely recorded) aspect of farm husbandry, the poem has a clear affinity with those other verses of Kavanagh's—early and late—which discover an essentially transcendent potential in the familiar seasonal labors of ploughing, harrowing, sowing, and harvesting which the poet had engaged in during his boyhood and young manhood in County Monaghan. Technically, "Spraying the Potatoes" reflects Kavanagh's generally casual attitude toward both prosodic and stylistic concerns which afflicts much of his poetry. Composed in quatrains of loose iambic tetrameter lines occasionally, and arbitrarily, extended to pentameter, the poem is characterized both by memorably vivid imagery—"The axle-roll of a rut-locked cart / Broke the burnt stick of noon in two"—and by artless and irrelevant diction: "We talked and our talk was a theme of kings, / A theme for strings." With similar inconsistency, it is distinguished both by Kavanagh's trademark attention to local detail in his identifying the potatoes as Kerr's Pinks and Arran Banners and by a distractingly abrupt shift in point of view, from the immediacy of the first-person perspective of the first seven stanzas to the detached omniscience of the third-person in the final stanza (Complete Poems 72-73). Yet, while unto themselves those intrinsic qualities—thematic and technical—of "Spraying the Potatoes" help to locate the poem centrally in Kavanagh's œuvre, their significance is even more resonant in light of the poem's provenance in the midst of one of the many controversies provoked by Kavanagh during his career as commentator and reviewer for various Dublin journals and magazines. Well-known for his cantankerousness in person, the poet proved equally contentious in his critical writings, subjecting to ruthless scrutiny both individuals and institutions in his frequently insightful—but sometimes merely inciting—articles and columns published over several decades in The Irish Times, The Standard, The Bell, Envoy, and many other publications (including, of course, Kavanagh's Weekly, a short-lived tabloid of cultural commentary and criticism founded and written almost exclusively by the poet and his brother Peter). From F. R. Higgins to Frank O’Connor, from The Capuchin Annual to the New Critics, from local Art Councils to continental painters, the targets of Kavanagh’s more merciless offensives were themselves usually inoffensive by most reasonable standards, as reflected in several cases in dissenting responses printed in letters to the editor—or indeed as reflected in at least one instance in an editorial disclaimer accompanying Kavanagh’s patently questionable diatribe. Of all of the controversies associated with Kavanagh, however, that initiated by his review of Maurice Walsh’s novel The Hill is Mine in July of 1940 may reveal most acutely the extent to which the poet, while never truly the “green fool” of his purported autobiography published in 1938, nonetheless continued to find in the rustic simplicity of his life “Ere Dublin taught him to be wise” (Complete Poems 20) a consolation—if not quite an antidote—for the pseudo-urbanity of the Irish metropolis that he had adopted as his home in the late 1930s. As Antoinette Quinn has observed of Kavanagh’s relocation from Iniskeen to Dublin, “once he was at a physical remove from his home place he experienced a Romantic ‘return in Departure’ and 1939 to 1942 were four glorious years for his poetry. Now that he had abandoned his few paternal acres he was at last content to breathe his native air and to farm the land imaginatively in poem after poem” (88). In the case of “Spraying the Potatoes”—written, as the poet’s brother annotates it, in “response to the controversy” created by Kavanagh’s review of Walsh’s novel (Complete Poems 393), and first published in The Irish Times one week after that review, on July 27, 1940—not only the immediacy of the evocation of rural experience but equally the very form and substance of the poem qua poem represent a major statement of Kavanagh’s true “aesthetic.” Subsequently compromising this aesthetic during the latter half of the 1940s and the first half of the ’50s to indulge that antithetical impulse toward inelegant and vitriolic expression in his vindictive exposés of and harangues against the Dublin literary establishment, Kavanagh would muse in 1964: “Curious this, how I had started off with the right simplicity, indifferent to crude reason and then ploughed my way through complexities of anger, hatred and ill-will towards the faults of man, and came back to where I started” (Self-Portrait 26). I Curious, too, that Kavanagh’s review of The Hill is Mine should have precipitated—or at least anticipated—those twisted furrows (as it were) of his middle years as poet. Not yet the literary and cinematic footnote that he would eventually become after the silver-screen adaptation in 1952 of his 1935 short story “The Quiet Man,” Maurice Walsh was nonetheless an innocuously popular writer during his lifetime, and his tenth book is neither more nor less enduring than the twenty-odd other works of fiction that he published between 1926 and 1964. Set in the highlands of Scotland (a native of North Kerry, Walsh worked for several years as a Scottish customs and excise officer before settling in Stillorgan, Co. Dublin, and maintained a life-long affection for Scottish settings, for Scottish women—he married one—and for Scotch whiskey), *The Hill is Mine* actually bears a coincidental resemblance to "The Quiet Man" which, as a romantic corrective to the dogmatic—or dogged—realism of George Moore’s "Home Sickness" (1903), represents an important variation on the theme of the "returned Yank." Recounting in colorful detail the initiation of a young American rancher into the ways and the wiles of the lords and the ladies—and even more the lad­dies—who inhabit the countryside around the small "croft" he has inherited from his grandmother, the novel pretends to little more than wholesome entertainment. Perhaps not surprisingly, the book was a best-seller in Dublin throughout July of 1940, and contemporary reviews were almost unanimously complimentary. Indeed, Kavanagh’s own review of *The Hill is Mine*, concluding with the judgment that the novel “may not appeal to literary readers, but it will delight all who enjoy a romantic story, told with great skill, and sometimes illuminated by a poet’s vision,” is ultimately—if not quite unequivocally—favor­able.¹ Appreciating Walsh’s ability to ground the "fantasy" of his narrative “upon the crags of reality” and admiring his charming “sense of humour,” Kavanagh complains only that the novel suffers from an excess of “bonnie, boring Scotland” and from a lack of engaging moral ambiguity—"a slight flavour of real sin," as he puts it (Irish Times, July 20, 1940). As generous as it is judicious, this reading of *The Hill is Mine* should have proved exception­able to none but the most ardent of Maurice Walsh’s loyal readers—had Kavanagh for once refrained from using the occasion of a review to offer critical commentary not only on the book at hand but also on other matters of less immediate relevance. But, as John Nemo has observed, Kavanagh dis­played even in his earliest published criticism the inclination toward wide-ranging proclamations that was to characterize his critical writing throughout his career: Impulsive, egotistical and perpetually romantic, when he examined either life or literature he tended to communicate his creative intensity rather than detail his intellectual response. As a result, when he turned his energies to criticism he often over-reacted, declaring absolutes and making generalizations which satisfied his artistic passion but confused his critical position. ("The Green Knight" 283) Typically enough, then, his review of Walsh’s novel includes if not devastat­ing broadsides then at least agitating asides directed at more or less innocent 1. Nine years later, however, Kavanagh would show considerably less generosity toward Walsh in casting him—according to the poet’s brother Peter (Complete Poems 400)—as "the Devil Mediocrity" in his poem "The Paddiad": He has written many Catholic novels, None of which mention devils: Daring men, beautiful women, Nothing about muck or midden, Wholesome atmosphere—Why must So-called artists deal with lust? (Complete Poems 213) bystanders in what would escalate over the years into the poet’s personal war against the forces of literary and cultural philistinism in Ireland. Plausibly, Kavanagh may have intended to provoke more than mere thought in his readers by his casual dismissal of the “empty virtuosity” of Hopkins and Eliot and the later Yeats and Joyce and his unrestrained discrediting of “stupid, boring books, like Gone With the Wind.” Probably, however, he could not have expected his irrelevant declaration that “The boy scout may be said to represent civilisation at its lowest”—an offhanded follow-up to his observation that Walsh’s characters incline toward “the open-air boy scout type”—to act as the primary catalyst to an unusually prolonged and singularly profuse disputation among readers of The Irish Times. Responding to a letter to the editor signed “F.L.J.” published on July 22nd which took exception to Kavanagh’s “remarkable, and quite unnecessary opinions,” one Oscar Love initiated on July 23rd an epistolary exchange which would continue, under the heading “Literary Criticism,” for more than a fortnight, involving a full fifty letters composed by—ostensibly—almost forty different correspondents (Irish Times, July 22–August 7, 1940).2 Seemingly perturbed by the arbitrariness of critical pronouncements, Love asserted that Kavanagh “made a slight error” in demeaning the boy scout: It would have been wiser to omit the word “scout.” The boy represents civilisation at its lowest, and long may he remain so. Only the grown man develops and rejoices in the art of destruction. Failing to detect the obviously intended irony of Love’s statement in its chastening allusion to literary critics like Kavanagh, not only F. L. J. but also Harold C. Brown and Frank E. Prenton Jones responded on July 24th in righteous defense of the Boy Scout movement. Their letters in turn prompted a rebuttal by Love, followed the next day by counter-rebuttals by both F.L.J. and Jones. “I prithee let this bedlamite orchestra play on,” reader M. C. Ahern exhorted The Irish Times on July 26th, as if any circulation-conscious editor would even consider interrupting a debate of such apparently spontaneous combustibility.3 For the next week-and-a-half, in fact, the controversy generated by Kavanagh’s review of The Hill is Mine produced a true polyphony of Dublin opinion: from Ewart Milne’s apologia for his fellow poet in the face of “the gnats’ nest” he had disturbed by his review to anonymous and pseudonymous comparisons of the Boy Scout movement and the Hitler-Jugend; from Dublin wit Niall Montgomery’s expression of incredulity that the traditionally West Briton Irish Times should publish a comment even glancingly critical of Yeats to various correspondents’ musings on the aptness of the sewer as a metaphor for belletristic ambition and accomplishment in Ireland. The remarkably disparate chorus of accents and attitudes notwithstanding, the 2. A representative selection of these letters has been reprinted in John Wyse Jackson, ed., Myles Before Myles (203–26). 3. Indeed, according to Peter Kavanagh (Sacred Keeper 92), the editor himself of The Irish Times, R. M. Smyllie, contributed a letter on July 31st over the pseudonym (The) O’Madan. cumulative effect of missives ranging in tone from the presumably earnest—a recommendation by R.H.S. on July 30th of Spinoza as “the greatest literary critic of all time”—to the certifiably inane—Judy Clifford’s account on July 27th of her disappointing meeting with some Boy Scouts in Co. Wicklow—was, perhaps inevitably, a decided facetiousness. For in another literary footnote associated with Maurice Walsh, many of the more blusterous (or preposterous) responses to Kavanagh’s review—including letters written backwards (to reflect the direction the discussion seemed to be moving) or in imitation of Joyce’s recently published *Finnegans Wake*—evidently originated with just one writer: the already pseudonymous litterateur Flann O’Brien. Resurrecting the spirit of two lesser controversies that he had enlivened with his friend Niall Montgomery in *The Irish Times* in 1939 and earlier in 1940, O’Brien—or Brian O’Nolan as he was properly known—would shortly parlay the public interest in these mock debates into the regular column “Cruiskeen Lawn” published under the byline Myles na Gopaleen; on this occasion, however, the adoption by the prodigiously polynomial O’Nolan of monikers as diverse as Oscar Love, Lir O’Connor, Miss (alas) Luna O’Connor, W.R. Lambkin, and Whit Cassidy appears to have had no purpose other than to annoy the burgeoning rustic man of letters Patrick Kavanagh. Indeed, although Kavanagh’s review had obviously invited reaction, the pedal point in the ensuing correspondence shifted gradually but unmistakably from Kavanagh the critic to Kavanagh the artist as more and more voices entered the contrapuntal imbroglio. The first of two especially captious motifs appeared four days after the review when Frank E. Prenton Jones recollected with disgust a “short story” written by Kavanagh “some months ago, which dealt with the lower order of potato-diggers and their vulgar remarks about the serving maids of the village.” Impressively, given that the piece alluded to seems to be neither the anecdote “Planting the Potatoes” which was printed in *The Irish Times* on May 4, 1940 nor even the pastoral reminiscence published on October 25, 1939 as “A Rural Irish Contrast” to the war in Europe but rather a sketch entitled “Sentimental Ploughman” which appeared on May 30, 1939—almost fourteen months before the Walsh review—Oscar Love confidently patronized it the next day as “a delightful article,” observing that “Mr. Jones should recognise that the lowest orders are more original than university graduates, for they are not moulded in the college sausage machine.” Just as impressively, N. S. Harvey of Co. Tipperary and F.L.J. of Glasnevin confidently corroborated Jones’s very specific recollection of a very minor bit of hack writing on Kavanagh’s part, and other contributors to the debate referred to it with rather unlikely familiarity as well. With possibly even less provocation, a number of readers—led by “F. O’Brien” on July 29th—responded with similar picayune faultfinding to the publication of Kavanagh’s poem “Spraying the Potatoes” one week into the Walsh controversy. Inspired by the poem’s being printed inside a border that made it look like a five-pound note, O’Brien wrote: I had naturally enough inferred that our bank notes were being treated periodically with a suitable germicide, a practice which has long been a commonplace of enlightened monetary science in Australia. When I realised that the heading had reference to some verses by Mr. Patrick Kavanagh dealing with the part played by chemistry in modern farming, my chagrin may be imagined. Perhaps the Irish Times, tireless champion of our peasantry, will oblige us with a series in this strain covering such rural complexities as inflamed goat-udders, warble-pocked shorthorn, contagious abortion, non-ovoid oviducts and nervous disorders among the gentlemen who pay the rent. The following day, Lir O’Connor, apostrophizing to Kavanagh, declared that the poem would not suffice as “convincing literary proof of your existence,” and Oscar Love feigned sympathy for the poet, wondering: “Is Mr. Kavanagh crazy? He now puts another weapon in his critics’ hands. In ‘Spraying the Potatoes’—which my ten-year-old niece enjoyed reading—Mr. Kavanagh writes of ‘young girls swinging from the sky.’ It is really indecent to write thus of a parachutist in slacks.” More pettily (and less Wittily) a reader employing as a pseudonym the chemical formula “Cu SO4”—for the compound sprayed on potatoes—refused to acknowledge a typesetting error in the fourth stanza of the poem: “In one line a wasp is poised on the edge of a barrel; in the next he is afloat on the surface of the liquor. A brimful barrel would explain it, but it is hardly worth explaining.” Several days later, an apparent competitor—“Na 2 Co 3”—complained: Another appreciative reader of poetry is perturbed by the thought that the blossoms of Arran Banners, described as blue, are in reality white. It is doubtful if poetic licence permits such an inaccuracy as this, and I think Mr. Kavanagh should severely reprimand his Muse for not having consulted the Department of Agriculture’s leaflet on potatoes (sent free on application) before inspiring him. II UNDERSTANDABLY, IN LIGHT of the many abrasive remarks directed toward Kavanagh personally during this two-week riot of epistolography, a commentator writing in The Honest Ulsterman three decades after the fact might imagine Kavanagh’s being utterly bemused by both the extent and the nature of the response elicited by his review of The Hill is Mine: Poor Kavanagh. God knows he had plenty of real problems to contend with. He must have been bewildered at this sudden eruption of quite causeless, meaningless schoolboy aggression [sic] conducted by such a frighteningly united bunch of juvenile delinquents. The message must have been clear to him—You are not one of us. You are not of our class. You have not had our education. You are not a Dubliner. Shut up or get out.” (Jude the Obscure 29) Contesting this supposition, Flann O’Brien’s biographer Anthony Cronin claims that “Kavanagh does not seem to have interpreted the correspondence this way; and in later years anyway he had certainly no animus against Brian O’Nolan on the head of it” (121). The poet’s brother Peter actually recalls that “Patrick and I enjoyed it immensely” (Sacred Keeper 97); and, indeed, Kavanagh’s own letter to the editor which finally closed the controversy on August 7th acknowledges that, while “all very adolescent,” the exchange of letters was also “at times faintly amusing.” He took particular satisfaction in reading the letters in the afterglow of his original review: In my review of Maurice Walsh’s “The Hill is Mine” I referred to the empty virtuosity of artists who were expert in the art of saying nothing. Ploughmen without land. One of my critics said it was a wistful remark, and, maybe, it was; but if ever a critic was proved right, all round, by his critics it happened this time. Concluding with uncharacteristic equanimity that “On the serious letters I do not intend to comment here,” Kavanagh seemingly decided in his conventional response to the controversy to defer direct confrontation with the philistine faction he perceived as enjoying majority rule in Dublin’s literary and cultural politics. As an unconventional “response to the controversy,” however, Kavanagh’s poem “Spraying the Potatoes,” published on The Irish Times book page about halfway through the Walsh debate, represents a subtle—even a subversive—expression of the delicate but desirable equipoise among polemics, poetics and literary politics that would subsequently elude the poet for almost two decades. For as the stone (as it were) in the midst of all, the poem does truly trouble, in terms Kavanagh suggested in 1958 in a lecture series entitled “Studies in the Technique of Poetry,” that stream of condensation—hurtful or playful—which finally engulfed the essential integrity of his review of The Hill is Mine. His mind, the poet asserted in his fourth lecture delivered at University College Dublin, “keeps saying that it is only by realising the full folly and nature of society and the things it will accept in the way of culture that you can understand the necessity for your own polemic, the need to state your own point of view” (“Extracts” 61); of course, beginning with “A Wreath for Tom Moore’s Statue” in 1944 and continuing well into the 1950s with such poems as “The Wake of the Books,” “The Paddiad,” “The Defeated,” and “The Christmas Mummers,” Kavanagh had elected against his own better judgment to follow “The Road to Hate” (Complete Poems 211) as his response to the hostility he experienced on the streets, in the pubs, and in the literary parlors of Dublin. But in “Spraying the Potatoes” he seems clearly to transform the sense of absolute displacement which would determine so much of that later verse into a statement of absolute transcendence of the sort he described in his seventh lecture: A poet is interested in his own private world; he luxuriates in telling the truth; he never argues or holds a symposium to find out what to think on any given subject. Neither does a poet preach; he makes statements about what is. The statement floats free of common didacticism in a realm of pure logic; you can walk around it and examine it but you can do nothing about it. You can only attack the person of the man who released the statement, and that is the thing generally done. Only a few brave virtuous people are willing to recognize and honour the Logos when they experience it. (“Extracts” 68) 4. As Peter Kavanagh mentions in a note in The Complete Poems (401–02), these lectures were misdated 1956 in November Haggard. For Kavanagh, then, as for fellow Ulster poet-in-exile (and preeminent Kavanagh apologist) Seamus Heaney, who muses thirty years later on the response of some poets of contemporary Northern Ireland to a literary politics of at least equal volatility, “The only reliable release for the poet was the appeasement of the achieved poem”: In that liberated moment, when the lyric discovers its buoyant completion, when the timeless formal pleasure comes to its fullness and exhaustion, in that moment of self-justification and self-obliteration the poet makes contact with the plane of consciousness where he is at once intensified in his being and detached from his predicaments. (“Place and Displacement” 163) Thus, to the extent that they reflect what Heaney emphasizes as “the profound relation . . . between poetic technique and historical situation” (164), even the stylistic and prosodic imperfections of “Spraying the Potatoes” reinforce the subtle and subversive “polemic” of Kavanagh’s poem. For as Heaney observes in his essay “Feeling into Words,” poetic technique must be distinguished from the learned “skill of making,” from mere poetic craft: Technique . . . involves not only a poet’s way with words, his management of metre, rhythm and verbal texture; it involves also a definition of his stance towards life, a definition of his own reality. It involves the discovery of ways to go out of his normal cognitive bounds and raid the inarticulate: a dynamic alertness that mediates between the origins of feeling in memory and experience and the formal ploys that express these in a work of art. (47) Or as Kavanagh asserts more succinctly in the first of his 1958 lectures, “The question of technique is not simply a matter of grammar and syntax or anything as easy as that. It has to do with the mystical” (“Extracts” 57). Obviously, the “mystical” dimension of “Spraying the Potatoes” involves the process by which the poet’s lyrical recollection of the life he had abandoned to pursue his muse can sustain him in the face of the inhospitable reception given him by Dublin’s literary establishment. “So does a poem bring a world alive in my mind,” he would write more than a quarter-century later in the second of his “Shancoduff” poems, an impressionistic but unsentimental evocation of that same Iniskeen townland he had first extolled in verse in 1934: immersing himself once more in a world of rushy fields, of scythes and flails, of knapsack sprayers—“Put on four barrels / Filled with a porringer tin”—Kavanagh acknowledges in 1966 his completion of clearly the same sort of “long day’s journey into night and day the same day” (Complete Poems 346–47) that he had undertaken during the Walsh controversy in 1940. The affectionately reproduced details of the first seven stanzas of “Spraying the Potatoes” thus affording him a literary transportation truly beyond the Pale, the unfelicitously transplanted countryman Kavanagh achieves in the third-person perspective of the final stanza of the poem— And poet lost to potato-fields, Remembering the lime and copper smell Of the spraying barrels he is not lost Or till blossomed stalks cannot weave a spell— a literal transcendence of the kind hinted at in the ninth of his UCD lectures: “The purpose of technique is to enable us to detach our experience from ourselves and see it as a thing apart” (“Extracts” 73). III SUBTLY, THEN, BUT SURELY, “Spraying the Potatoes” substantiates Heaney’s insistence that “The idea of poetry as a symbolic resolution of opposing truths, the idea of the poem as having its existence in a realm separate from the discourse of politics, does not absolve it or the poet from political status” (“Place and Displacement” 164). Just as subtly, however, the poem reveals the transience of its own transcendence in validating Heaney’s corollary that the poet can be “stretched between politics and transcendence, and is often displaced from a confidence in a single position by his disposition to be affected by all positions, negatively rather than positively capable” (164). For in acknowledging the intrinsic fickleness of nature at the same time that it presents the possibility for romantic engagement with nature, “Spraying the Potatoes” serves as a poetic milestone—a referential point of both departure and return—not only with regard to Kavanagh’s “Adventures in the Bohemian Jungle” (as he entitled one of his more caustic satires directed against literary and cultural Dublin), but also with regard to his verses of the early 1940s which manifest such seemingly deep-rooted antipathy toward the same world and life that he had celebrated during the first dozen years of his career as poet. Of course, “Spraying the Potatoes” does not approach the fullest articulation of that antipathy, found in the jaundiced perspective of The Great Hunger, first published in 1942 and subsequently reprinted with “Spraying the Potatoes” in A Soul for Sale five years later. Yet, introducing in the fourth stanza of the poem, through his dispassionate description of the lethal potency of the lime and copper compound used to combat potato blight—“A wasp was floating / Dead on a sunken briar leaf / Over a copper-poisoned ocean”—a counter to his more typically whimsical personification of the wild roses, the potato-stalks and the dandelions as “young girls” with unloved hearts” which had constituted the first three stanzas, Kavanagh seems truly to anticipate the spirit of dis-ease with rural living which would occasionally find expression in his verse in the next decade-and-a-half. Indeed, by employing the conventionally romantic mode of the lyric to depict and reflect upon a farming chore of a decidedly unromantic and truly consequential sort, Kavanagh ultimately (albeit without apparent conscious design) locates the poem in conspicuous apposition to “Stony Grey Soil,” the 5. In a note to “Spraying the Potatoes” Peter Kavanagh explains: “To prevent ‘the blight’ potatoes had to be sprayed at least twice—in June and July, using a mixture of copper-sulphate and washing soda melted in a forty-gallon barrel of water. The barrel was placed conveniently on the headland. A two-gallon capacity back-carried sprayer was rented in the Village. Patrick sprayed the potatoes by walking up and down each furrow, the sprayer on his back. Around forty pounds weight or more. You came home tired after that day’s work” (The Complete Poems 392). THOMAS B. O’GRADY 251 poem printed immediately after it in the chronologically arranged Complete Poems and the earliest expression of his temperamental—if temporary—rejection of the hills and the fields of Iniskeen and environs which had so inspired him from his earliest poetic efforts: O stony grey soil of Monaghan The laugh from my love you thieved; You took the gay child of my passion And gave me your clod-conceived. (Complete Poems 73) First printed in The Bell in October of 1940, this poem, seemingly presenting through its emphasis on the dark underside of Irish country life a pronounced contrast to the prevailing transcendence of “Spraying the Potatoes,” actually brings into high relief the equivocation which quietly but insistently infiltrates the earlier poem. Even Kavanagh’s redirecting his attention in the penultimate stanzas to the plants and the flowers to dismiss the old man who interrupts his reverie—“O roses / The old man dies in the young girl’s frown”—may be read as a willful (as opposed to a more characteristically wistful) repression of the sobering threat of blight inevitably suggested by the preventive measure of spraying and vaguely yet ominously mused upon by the old man’s echoing “an ancient farming prayer.” As Antoinette Quinn has remarked, Kavanagh had allowed “worldly doubt to trouble poetic faith” (45) as early as the mid-1930s, taking literally to heart the negative evaluation of his black-hilled holding by insensitive cattle-drovers: “I hear and is my heart not badly shaken?” (Complete Poems 13). In 1951, beginning to disentangle himself from the “complexities of anger, hatred and ill-will towards the faults of man” which so possessed him during the 1940s, he recalled the aftereffect of that first “Shancoduff” poem in verses appropriately entitled “Innocence”: “Ashamed of what I loved,” he admits, “I flung her from me and called her a ditch / Although she was smiling at me with violets.” Briefly revisiting those familiar fields, however, he realizes that “I cannot die / Unless I walk outside these white-thorn hedges” (Complete Poems 241–42). In this respect, while straddling the boundary (as it were) between affection for and disaffection with the life of the Irish countryman—presumably the hedges in “Innocence” are the same ones that “the gulls like old newspapers are blown clear of . . . luckily” in The Great Hunger (Complete Poems 80)—“Spraying the Potatoes” may ultimately affirm its transcendent and transporting lyricism and function as a poetic landmark warranting Patrick Kavanagh’s eventual willing and willful return, in the last half-dozen years of his life and career, to a Monaghan both actual and imaginary: to that “right simplicity” he had so abruptly abandoned in the aftermath of the Walsh controversy in the summer of 1940. Works Cited ------. “Maurice Walsh’s New Novel.” The Irish Times 20 July 1940. “Literary Criticism.” The Irish Times 22 July–7 August 1940.
Abstract This paper considers the estimation of approximate dynamic factor models when there is temporal instability in the factor loadings. We characterize the type and magnitude of instabilities under which the principal components estimator of the factors is consistent, and find that these instabilities can be larger than earlier theoretical calculations suggest. We further characterize the rate of convergence of the estimated factors as a function of the magnitude of the time variation in the factor loadings for general types of parameter instability, and provide numerical evidence that this consistency rate is tight in the special case of random walk parameter variation. We also discuss implications of these results for the robustness of regressions based on the estimated factors and of estimates of the number of factors in the presence of parameter instability. 1 Introduction Dynamic factor models (DFMs) provide a flexible framework for simultaneously modeling a large number of macroeconomic time series. In a DFM, a potentially large number of observed time series variables are modeled as depending on a small number of unobserved factors, which account for the widespread co-movements of the observed series. Although there is now a large body of theory for the analysis of high-dimensional DFM, nearly all of this theory has been developed for the case in which the DFM parameters are stable, in particular, in which there are no changes in the factor loadings (the coefficients on the factors); among the few exceptions are Stock and Watson (2002, 2009) and Breitung and Eickmeier (2011). This assumption of parameter stability, however, is at odds with broad evidence of time variation in many macroeconomic forecasting relations. The goal of this paper is to characterize the type and magnitude of parameter instability that can be tolerated by a standard estimator of the factors, the principal components estimator, in a DFM when the coefficients of the model are unstable. In so doing, this paper contributes to a larger debate about how best to handle the instability that is widespread in macroeconomic forecasting relations. On the one hand, the conventional wisdom is that time series forecasts deteriorate when there are undetected structural breaks or unmodeled time-varying parameters, see for example Clements and Hendry (1998). This view underlies the large literatures on the detection of breaks and on models that incorporate breaks and time variation, for example by modeling the breaks as following a Markov process (Hamilton, 1989; Pesaran et al., 2006). In the context of DFM, Breitung and Eickmeier (2011) show that a one-time structural break in the factor loadings has the effect of introducing new factors, so that estimation of the factors ignoring the break leads to estimating too many factors. On the other hand, a few recent papers have provided evidence that sometimes it can be better to ignore parameter instability when forecasting. Pesaran and Timmermann (2005) point out that whether to use pre-break data for estimating an autoregression trades off an increase in bias against a reduction in estimator variance, and they provide empirical evidence supporting the use of pre-break data for forecasting. Pesaran and Timmermann (2007) go on to provide tools to help ascertain in practice whether pre-break data should be used for estimation of single-equation time series forecasting models. In DFM, Stock and Watson (2009) provide empirical evidence using U.S. macroeconomic data from 1960-2007 that full-sample estimates of the factors are preferable to subsample estimates, despite clear evidence of a break in many factor loadings around the beginning of the Great Moderation in 1984. We therefore seek a precise theoretical understanding of the effect of instability in the factor loadings on the performance of principal components estimators of the factors. Specifically, we consider a DFM with \( N \) variables observed for \( T \) time periods and \( r \ll N \) factors, where the \( N \times r \) matrix of dynamic factor loadings \( \Lambda \) can vary over time. We write this time variation so that \( \Lambda \) at date \( t \) equals its value at date 0, plus a deviation; that is, \( \Lambda_t = \Lambda_0 + h_{NT} \xi_t \). The term \( \xi_t \) is a possibly random disturbance, and \( h_{NT} \) is a deterministic scalar sequence in \( N \) and \( T \) which sets the scale of the deviation. Using this framework and standard assumptions in the literature (Bai and Ng, 2002, 2006), we obtain general conditions on \( h_{NT} \) under which the principal components estimates are mean square consistent for the space spanned by the true factors. We then specialize these general results to three leading cases: i.i.d. deviations of \( \Lambda_t \) from \( \Lambda_0 \), random walk deviations that are independent across series, and an arbitrary one-time break that affects some or all of the series. For the case in which \( \Lambda_t \) is a vector of independent random walks, Stock and Watson (2002) showed that the factor estimates are consistent if \( h_{NT} = T^{-1} \). By using a different method of proof (which builds on Bai and Ng, 2002), we are able to weaken this result considerably and show that the estimated factors are consistent if \( h_{NT} = o(T^{-1/2}) \). We further show that, if \( h_{NT} = O(1/\min\{N^{1/4}T^{1/2}, T^{3/4}\}) \), the estimated factors achieve the mean square consistency rate of \( 1/\min\{N, T\} \), a rate initially shown by Bai and Ng (2002) in the case of no time variation. Because \( \xi_t \) in the random walk case is itself \( O(t^{1/2}) \), this means that deviations in the factor loadings on the order of \( o_p(1) \) do not break the consistency of the principal components estimator. These rates are remarkable: as a comparison, if the factors were observed so an efficient test for time variation could be performed, the test would have nontrivial power against random walk deviations in a \( h_{NT} \propto T^{-1} \) neighborhood of zero (e.g., Stock and Watson, 1998b) and would have power of one against parameter deviations of the magnitude tolerated by the principal components estimator. Intuitively, the reason that the principal component estimator can handle such large changes in the coefficients is that, if these shifts have limited dependence across series, their effect can be reduced, and eliminated asymptotically, by averaging across series. We further provide the rate of mean square consistency as a function of \( h_{NT} \), both in general and specialized to the random walk case. The resulting consistency rate function is nonlinear and reflects the tradeoff between the magnitude of the instability and, through the relative rate of \( N/T \) as increases, the amount of cross-sectional information that can be used to “average out” this instability. Although the bounds from which the consistency rate function is derived are tight using our method of proof, we cannot show that these rate function bounds provide necessary as well as sufficient conditions for consistency. We find numerically, however, that our theoretical consistency rate function matches Monte Carlo estimates of the rate functions, which suggests that no other method of proof could improve on these bounds (under our assumptions). The rest of the paper proceeds as follows. Section 2 lays out the model, the assumptions, and the three special cases. Asymptotic results are provided in Section 3. Section 4 provides Monte Carlo results, and Section 5 concludes. 2 Model and assumptions 2.1 Basic model and intuition The model and notation follow Bai and Ng (2002) closely. Denote the observed data by \( X_{it} \) for \( i = 1, \ldots, N, \ t = 1, \ldots, T \). It is assumed that the observed series are driven by a small number \( r \) of unobserved common factors \( F_{pt}, p = 1, \ldots, r \), such that \[ X_{it} = \lambda_{it}' F_t + e_{it}. \] Here \( \lambda_{it} \in \mathbb{R}^r \) is the possibly time-varying factor loading of data series \( i \) at time \( t \), while \( e_{it} \) is an idiosyncratic error. Define \( X_t = (X_{1t}, \ldots, X_{Nt})' \), \( e_t = (e_{1t}, \ldots, e_{Nt})' \), \( \Lambda_t = (\lambda_{1t}, \ldots, \lambda_{Nt})' \) and data matrices \( X = (X_1, \ldots, X_T)' \), \( F = (F_1, \ldots, F_T)' \). The initial factor loadings \( \Lambda_0 \) are fixed. We write the cumulative drift in the parameter loadings as \[ \Lambda_t - \Lambda_0 = h_{NT} \xi_t, \] where \( h_{NT} \) is a deterministic scalar that may depend on \( N \) and \( T \), while \( \{\xi_t\} \) is a possibly degenerate random process of dimension \( N \times r \) (in fact, it will be allowed to be a triangular array). Observe that \[ X_t = \Lambda_t F_t + e_t = \Lambda_0 F_t + e_t + w_t, \] where \( w_t = h_{NT} \xi_t F_t \). Our proof technique will be to treat \( w_t \) as another error term in the factor model. To establish some intuition for why estimation of the factors is possible despite structural instability, consider an independent random walk model for the time variation in the factor loadings, so that $\xi_{it} = \xi_{i,t-1} + \zeta_{it}$, where $\zeta_{it}$ is i.i.d. across $i$ and $t$ with mean 0 and variance $\sigma^2_\zeta$, and suppose that $\Lambda_0$ is known. In addition, we look ahead to Assumption 2 and assume that $\Lambda_0' N \rightarrow D$, where $D$ has full rank. Because $\Lambda_0$ is known, we can consider the estimator $\hat{F}_t(\Lambda_0) = (\Lambda_0' \Lambda_0)^{-1} \Lambda_0' X_t$. From (1), $$ \hat{F}_t(\Lambda_0) = F_t + (\Lambda_0' \Lambda_0)^{-1} \Lambda_0' e_t + (\Lambda_0' \Lambda_0)^{-1} \Lambda_0' w_t, $$ so $$ \hat{F}_t(\Lambda_0) - F_t \approx D^{-1} N^{-1} \sum_{i=1}^{N} \lambda_{i0} e_{it} + D^{-1} N^{-1} \sum_{i=1}^{N} \lambda_{i0} w_{it}. $$ The first term does not involve time-varying factor loadings and under limited cross-sectional dependence it is $O_p(N^{-1/2})$. Using the definition of $w_t$, the second term can be written $$ D^{-1} N^{-1} \sum_{i=1}^{N} \lambda_{i0} w_{it} = D^{-1} \left( h_{NT} N^{-1} \sum_{i=1}^{N} \lambda_{i0} \xi_{it} \right) F_t. $$ Since $F_t$ is $O_p(1)$, this second term is the same order as the first, $O_p(N^{-1/2})$, if $h_{NT} N^{-1} \sum_{i=1}^{N} \lambda_{i0} \xi_{it} = O_p(N^{-1/2})$. Under the independent random walk model, $\xi_{it} = O_p(T^{-1/2})$, so $$ h_{NT} N^{-1} \sum_{i=1}^{N} \lambda_{i0} \xi_{it} = O_p(h_{NT}(T/N)^{1/2}), $$ which in turn is $O_p(N^{-1/2})$ if $h_{NT} = O(T^{-1/2})$. This informal reasoning suggests that the estimator $\hat{F}_t(\Lambda_0)$ satisfies $\hat{F}_t(\Lambda_0) = F_t + O_p(N^{-1/2})$ if $h_{NT} = cT^{-1/2}$. In practice $\Lambda_0$ is not known so $\hat{F}_t(\Lambda_0)$ is not feasible. The principal components estimator of $F_t$ is $\hat{F}_t(\hat{\Lambda})$, where $\hat{\Lambda}$ is the matrix of eigenvectors corresponding to the first $r$ eigenvalues of the sample second moment matrix of $X_t$. The calculations below suggest that the estimation of $\Lambda_0$ by $\hat{\Lambda}$ reduces the amount of time variation that can be tolerated in the independent random walk case; setting $h_{NT} = cT^{-1/2}$ results in an $o_p(1)$ mean square discrepancy between $\hat{F}_t(\hat{\Lambda})$ and $F_t$. ### 2.2 Examples of structural instability For concreteness, we highlight three special cases that will receive extra attention in the following analysis. In these examples, the scalar $h_{NT}$ is left unspecified for now. We will set the number of factors $r$ to 1 for ease of exposition. Example 1 (white noise). All entries $\xi_{it}$ are i.i.d. across $i$ and $t$ with mean zero and $E(\xi_{it}^4) < \infty$. The factor loadings $\Lambda_t$ are then equal to the initial loading matrix $\Lambda_0$ plus uncorrelated noise. Example 2 (random walk). Entries $\xi_{it}$ are given by $\xi_{it} = \sum_{s=1}^t \zeta_{is}$, where $\{\zeta_{is}\}$ is a random process that is i.i.d. across $i$ and $s$ with mean zero and $E(\zeta_{is}^4) < \infty$. In this example, the factor loadings evolve as cross-sectionally uncorrelated random walks. Models of this type are often referred to as time-varying parameter models in the literature. Example 3 (single deterministic break). Let $\bar{\tau} \in (0, 1)$ be fixed and set $\kappa = [\bar{\tau}T]$, where $[\cdot]$ denotes the integer part. Let $\Delta \in \mathbb{R}^N$ be a shift parameter. We then define $$ \xi_t = \begin{cases} 0 & \text{for } t = 1, \ldots, \kappa \\ \Delta & \text{for } t = \kappa + 1, \ldots, T \end{cases} $$ Such deterministic shifts have been extensively studied in the context of structural break tests in the linear regression model. 2.3 Principal components estimation We are interested in the properties of the principal components estimator of the factors, where estimation is carried out as if the factor loadings were constant over time. Let $k$ denote the number of factors that are estimated. The principal component estimators of the loadings and factors are obtained by solving the minimization problem $$ V(k) = \min_{\Lambda^k, F^k} (NT)^{-1} \sum_{i=1}^N \sum_{t=1}^T (X_{it} - \lambda_i^k F_t^k)^2, $$ where the superscripts on $\Lambda^k$ and $F^k$ signify that there are $k$ estimated factors. It is necessary to impose a normalization on the estimators to pin down the minimizers (see Bai and Ng, 2008b, for a thorough treatment). Such restrictions are innocuous since the unobserved true factors $F$ are only identifiable up to multiplication by a non-singular matrix. One estimator \footnote{While conceptually clear, cross-sectional independence of the random walk innovations $\zeta_{it}$ is a stricter assumption than necessary for the subsequent treatment. It is straightforward to modify the example to allow $m$-dependence or exponentially decreasing correlation across $i$, and all the results below go through for these modifications.} of $F$ is obtained by first concentrating out $\Lambda^k$ and imposing the normalization $F^k F^k / T = I_k$. The resulting estimator $\tilde{F}^k$ is given by $\sqrt{T}$ times the matrix of eigenvectors corresponding to the largest $k$ eigenvalues of the matrix $XX'$. A second estimator is obtained by first concentrating out $F^k$ and imposing the normalization $\Lambda^k / \sqrt{N} = I_k$. This estimator equals $\bar{F}^k = X \bar{\Lambda}^k / N$, where $\bar{\Lambda}^k$ is $\sqrt{N}$ times the eigenvectors corresponding to the $k$ largest eigenvalues of $X'X$. Following Bai and Ng (2002), we use a rescaled estimator $$ \hat{F}^k = \tilde{F}^k (\tilde{F}^k \tilde{F}^k / T)^{1/2} $$ in the following. ### 2.4 Assumptions Our assumptions on the factors, initial loadings and the idiosyncratic errors are the same as in Bai and Ng (2002). The matrix norm is chosen to be the Frobenius norm $\|A\| = [\text{tr}(A'A)]^{1/2}$. The subscripts $i, j$ will denote cross-sectional indices, $s, t$ will denote time indices and $p, q$ will denote factor indices. $M \in (0, \infty)$ is a constant that is common to all the assumptions below. Finally, define $C_{NT} = \min\{N^{1/2}, T^{1/2}\}$. The following are Assumptions A–C in Bai and Ng (2002). **Assumption 1** (Factors). $E\|F_t\|^4 \leq M$ and $T^{-1} \sum_{t=1}^T F_t F_t' \to \Sigma_F$ as $T \to \infty$ for some positive definite matrix $\Sigma_F$. **Assumption 2** (Initial factor loadings). $\|\lambda_{i0}\| \leq \bar{\lambda} < \infty$, and $\|\Lambda_0' \Lambda_0 / N - D\| \to 0$ as $N \to \infty$ for some positive definite matrix $D \in \mathbb{R}^{r \times r}$. **Assumption 3** (Idiosyncratic errors). The following conditions hold for all $N$ and $T$. 1. $E(e_{it}) = 0$, $E|e_{it}|^8 \leq M$. 2. $\gamma_N(s, t) = E(e'_{s} e_{t} / N)$ exists for all $(s, t)$. $|\gamma_N(s, s)| \leq M$ for all $s$, and $T^{-1} \sum_{s, t=1}^T |\gamma_N(s, t)| \leq M$. 3. $\tau_{ij,ts} = E(e_{it} e_{js})$ exists for all $(i, j, s, t)$. $|\tau_{ij,tt}| \leq |\tau_{ij}|$ for some $\tau_{ij}$ and for all $t$, while $N^{-1} \sum_{i,j=1}^N |\tau_{ij}| \leq M$. Additionally, $$ (NT)^{-1} \sum_{i,j=1}^N \sum_{s,t=1}^T |\tau_{ij,ts}| \leq M. $$ 4. For every \((s,t)\), \(E|N^{-1/2}\sum_{i=1}^{N}[e_is - E(e_is)]|^4 \leq M\). As mentioned by Bai and Ng (2002), the above assumptions allow for weak cross-sectional and time dependence of the idiosyncratic errors. Note that the factors do not need to be stationary to satisfy Assumption 1. The assumptions we need on the factor loading innovations \(h_{NT}\xi_t\) are summarized below. For now we require the existence of three envelope functions that bound the rates, in terms of \(N\) and \(T\), at which certain sums of higher moments diverge. As we later state in Theorem 1, these rates determine the convergence rate of the principal components estimator of the factors. **Assumption 4** (Factor loading innovations). There exist envelope functions \(Q_1(N,T)\), \(Q_2(N,T)\) and \(Q_3(N,T)\) such that the following conditions hold for all \(N\), \(T\) and factor indices \(p_1, q_1, p_2, q_2 = 1, \ldots, r\). 1. \(\sup_{s \leq T} \sum_{i,j} |E(\xi_{is} \xi_{jt})| \leq Q_1(N,T)\). 2. \(\sum_{s,t} |E(\xi_{is} \xi_{jt} F_{sp_1} F_{tq_1})| \leq Q_2(N,T)\). 3. \(\sum_{s,t} |E(\xi_{is} \xi_{jt} F_{sp_1} F_{sq_1} F_{tp_2} F_{tq_2})| \leq Q_3(N,T)\). While consistency of the principal components estimator will require limited dependence between the factor loading innovations and the factors themselves, full independence is not necessary. This is empirically appealing, as it is reasonable to expect that breaks in the factor relationships may occur at times when the factors deviate substantially from their long-run means. That being said, we remark that if the processes \(\{\xi_t\}\) and \(\{F_t\}\) are assumed to be independent (and given Assumption 1), two sufficient conditions for Assumption 4 are that there exist envelope functions \(\tilde{Q}_1(N,T)\) and \(\tilde{Q}_3(N,T)\) such that for all factor indices, \[ \sup_{s,t \leq T} \sum_{i,j} |E(\xi_{is} \xi_{jt})| \leq \tilde{Q}_1(N,T) \tag{2} \] and \[ \sum_{s,t} |E(\xi_{is} \xi_{jt} F_{sp_1} F_{tq_1} F_{tp_2} F_{tq_2})| \leq \tilde{Q}_3(N,T). \tag{3} \] Under the above conditions, Assumption 4 holds with \(Q_1(N,T) \propto \tilde{Q}_1(N,T)\), \(Q_2(N,T) \propto T^2\tilde{Q}_1(N,T)\) and \(Q_3(N,T) \propto \tilde{Q}_3(N,T)\). Examples (continued). For Examples 1 and 2 (white noise and random walk), assume that \( \{\xi_t\} \) and \( \{F_t\} \) are independent. In Example 1 (white noise), the supremum on the left-hand side of (2) reduces to \( NE(\xi^2_t) \). By writing out terms, it may be verified that the quadruple sum in condition (3) is bounded by an \( O(NT^2) + O(N^2T) \) expression. Consequently, Assumption 4 holds with \( Q_1(N,T) = O(N) \), \( Q_2(N,T) = O(NT^2) \) and \( Q_3(N,T) = O(NT^2) + O(N^2T) \). In Example 2 (random walk), due to cross-sectional i.i.d.-ness we obtain \[ \sup_{s,t \leq T} \sum_{i=1}^N \sum_{j=1}^N |E(\xi_{is}\xi_{jt})| = N \sup_{s,t \leq T} |E(\xi_{is}\xi_{it})| = N \sup_{s,t \leq T} \left| \sum_{i=1}^s \sum_{v=1}^t E(\xi_{iu}\xi_{iv}) \right| = N \sup_{s,t \leq T} \min\{s, t\} E(\zeta^2_{i1}) = O(NT), \] so Assumptions 4.1–4.2 hold with \( Q_1(N,T) = O(NT) \) and \( Q_2(N,T) = O(NT^3) \). A somewhat lengthier calculation gives that the quadruple sum in condition (3) is \( O(N^2T^4) \) (a rate that cannot be improved upon), so Assumption 4.3 holds with \( Q_3(N,T) = O(N^2T^4) \). In Example 3 (single deterministic break), the supremum in inequality (2) evaluates as \[ \sum_{i=1}^N |\Delta_i| \sum_{j=1}^N |\Delta_j|. \] Assume that \( |\Delta_i| \leq M \) for some \( M \in (0, \infty) \) that does not depend on \( N \). We note for later reference that if \( |\Delta_i| > 0 \) for at most \( O(N^{1/2}) \) values of \( i \), the expression above is \( O(N) \). The same condition ensures that the left-hand side of condition (3) is \( O(NT^2) \). Consequently, we can choose \( Q_1(N,T) = O(N) \) and \( Q_2(N,T) = Q_3(N,T) = O(NT^2) \) if at most \( O(N^{1/2}) \) series undergo a break. Finally, rather than expanding the list of moment conditions in Assumption 4, we simply impose independence between the idiosyncratic errors and the other variables. It is possible to relax this assumption at the cost of added complexity.\(^3\) \(^3\)Bai and Ng (2006) impose independence of \( \{\varepsilon_t\} \) and \( \{F_t\} \) when providing inferential theory for regressions involving estimated factors. Assumption 5 (Independence). For all \((i,j,s,t)\), \(e_{it}\) is independent of \((F_s, \xi_{js})\). 3 Asymptotic theory 3.1 Consistent estimation of factors Our main result provides the mean square convergence rate of the usual principal components estimator under Assumptions 1–5. After stating the general theorem, we give sufficient conditions that ensure the same convergence rate that Bai and Ng (2002) obtained in a setting with constant factor loadings. Theorem 1. Let Assumptions 1–5 hold. For any fixed \(k\), \[ T^{-1} \sum_{t=1}^{T} \| \hat{F}_t^k - H_k F_t \|^2 = O_p(R_{NT}) \] as \(N,T \to \infty\), where \[ R_{NT} = \max \left\{ \frac{1}{C_{NT}^2} \frac{h_{NT}^2}{N^2} Q_1(N,T), \frac{h_{NT}^2}{N^2T^2} Q_2(N,T), \frac{h_{NT}^4}{N^2T^2} Q_3(N,T) \right\}, \] and the \(r \times k\) matrix \(H_k\) is given by \[ H_k = (\Lambda_0' \Lambda_0/N)(F' \hat{F}_k / T). \] See the appendix for the proof. If \(R_{NT} \to 0\) as \(N,T \to \infty\), the theorem implies that the \(r\)-dimensional space spanned by the true factors is estimated consistently in mean square (averaging over time) as \(N,T \to \infty\). While we do not discuss it here, a similar statement concerning pointwise consistency of the factors (Bai and Ng, 2002, p. 198) may be achieved by slightly modifying Assumptions 3–4. We now give sufficient conditions on the envelope functions in Assumption 4 such that the principal components estimator achieves the same convergence rate as in Theorem 1 of Bai and Ng (2002). This rate, \(C_{NT}^2\), turns out to be central for other results in the literature on DFM (Bai and Ng, 2002, 2006). The following corollary is a straightforward consequence of Theorem 1. Corollary 1. Under the assumptions of Theorem 1, and if additionally \[ \begin{align*} &\cdot h_{NT}^2 Q_1(N,T) = O(N), \\ &\cdot h_{NT}^2 Q_2(N,T) = O(NT^2), \\ &\cdot h_{NT}^4 C_{NT}^2 Q_3(N,T) = O(N^2T^2), \\ \end{align*} \] it follows that, as \( N, T \to \infty \), \[ C_{NT}^2 \left( T^{-1} \sum_{t=1}^{T} \| \hat{F}_t^k - H^k F_t \|^2 \right) = O_p(1). \] **Examples (continued).** In Section 2.4 we computed the envelope functions \( Q_1(N,T), Q_2(N,T) \) and \( Q_3(N,T) \) for our three examples. From these calculations we get that if \( h_{NT} = 1 \), the model in Example 1 (white noise) satisfies the conditions of Corollary 1. Hence, uncorrelated order-\( O_p(1) \) white noise disturbances in the factor loadings do not affect the asymptotic performance of the principal components estimator. Likewise, it follows from our calculations that the structural break process in Example 2 (random walk) satisfies the conditions of Corollary 1 if \( h_{NT} = O(1/\min\{N^{1/4}T^{-1/2}, T^{3/4}\}) \). Moreover, a rate of \( h_{NT} = o(T^{-1/2}) \) is sufficient to achieve \( R_{NT} = o(1) \) in Theorem 1, i.e., that the factor space is estimated consistently. This is a weaker rate requirement than the \( O(T^{-1}) \) scale factor imposed by Stock and Watson (2002). For Example 3 (single deterministic break), Corollary 1 and our calculations in Section 2.4 yield that if we set \( h_{NT} = 1 \), the principal components estimator achieves the Bai and Ng (2002) convergence rate, provided at most \( O(N^{1/2}) \) series undergo a break. A fraction \( O(N^{-1/2}) \) of the series may therefore experience an order-\( O(1) \), perfectly correlated shift in their factor loadings without affecting the asymptotic performance of the estimator. ### 3.2 Estimating the number of factors Bai and Ng (2002) introduced a class of information criteria that consistently estimate the true number \( r \) of factors when the factor loadings are constant through time. Lemma 2 of Amengual and Watson (2007) establishes that, under essentially the same assumptions as used by Bai and Ng, these information criteria remain consistent for \( r \) when the data \( X \) are measured with an additive error, i.e., if the researcher instead observes \( \tilde{X} = X + b \) for an \( T \times N \) error matrix \( b \) that satisfies \( (NT)^{-1} \sum_{t=1}^{N} \sum_{i=1}^{T} b_{it}^2 = O_p(C_{NT}^{-2}) \). By our decomposition (1) of \( X_t \), time variation in the factor loadings may be seen as contributing an extra error term \( w_t \) to the usual terms \( \Lambda_0 F_t + e_t \). It therefore follows from the Amengual and Watson result that for an appropriate choice of the scale factor \( h_{NT} \), the information criteria will remain consistent under time variation. For example, it may be verified that in Example 2 (random walk), a scale factor \( h_{NT} = O(T^{-1}) \) will ensure that the \( w_t \) term satisfies Amengual and Watson’s condition. It is a topic for future research to determine whether this rate can be improved upon. ### 3.3 Diffusion index forecasting As an application of Corollary 1, consider the diffusion index model of Stock and Watson (1998, 2002) and Bai and Ng (2006). For ease of exposition we assume that the factors are the only explanatory variables, so the model is \[ y_{t+h} = \alpha' F_t + \varepsilon_{t+h}. \] Here \( y_{t+h} \) is the scalar random variable that we seek to forecast, while \( \varepsilon_{t+h} \) is an idiosyncratic forecast error term that is independent of all other variables. We shall assume that the true number of factors \( r \) is known. Because the true factors \( F_t \) are not observable, one must forecast \( y_{t+h} \) using the estimated factors \( \hat{F}_t \). Does the sampling variability in \( \hat{F} \) influence the precision and asymptotic normality of the feasible estimates of \( \alpha \)? Let \( \hat{F} \) be the principal components estimator with \( k = r \) factors estimated and denote the \( r \times r \) matrix \( H' \) from Theorem 1 by \( H \). Define \( \delta = H^{-1} \alpha \) (note that due to the factors being unobservable, \( \alpha \) is only identified up to multiplication by a nonsingular matrix) and let \( \hat{\delta} \) be the least squares estimator in the feasible diffusion index regression of \( y_{t+h} \) on \( \hat{F}_t \). Bai and Ng (2006) show that \[ \sqrt{T}(\hat{\delta} - \delta) = (T^{-1} \hat{F}' \hat{F})^{-1/2} T^{-1/2} \hat{F}' \varepsilon - (T^{-1} \hat{F}' \hat{F})^{-1}[T^{-1/2} \hat{F}'(\hat{F} - FH)]H^{-1} \alpha, \] where \( \varepsilon = (\varepsilon_{1+h}, \ldots, \varepsilon_{T+h})' \). Under the assumptions of Corollary 1, the Cauchy-Schwarz inequality yields \[ \|T^{-1/2} \hat{F}'(\hat{F} - FH)\|^2 \leq T \left( T^{-1} \sum_{t=1}^{T} \|\hat{F}_t\|^2 \right) \left( T^{-1} \sum_{t=1}^{T} \|\hat{F}_t - H' F_t\|^2 \right) = TO_p(1)O_p(C_{NT}^{-2}) = O_p(1). \] Similarly, $$T^{-1/2} \hat{F}' \varepsilon = T^{-1/2} H' F' \varepsilon + T^{-1/2} (\hat{F} - FH)' \varepsilon = T^{-1/2} H' F' \varepsilon + O_p(1).$$ Suppose $T^{-1/2} F' \varepsilon = O_p(1)$, as implied by Assumption E in Bai and Ng (2006). It is easy to show that $H = O_p(1)$. The preceding calculations then suggest that $\hat{\delta} - \delta = O_p(T^{-1/2})$, i.e., the feasible diffusion regression estimator is consistent at the usual rate. Going further, if $\alpha = 0$, which is often an interesting null hypothesis in applied work, the second term on the right-hand side of the decomposition (4) vanishes. Assume that $\{\varepsilon_{t+h}\}$ is independent of all other variables. Then, conditional on $\hat{F}$, the first term on the right-hand side of (4) will (under weak conditions) obey a central limit theorem, and so it seems reasonable to expect that $\hat{\delta}$ should be unconditionally asymptotically normally distributed under the null $H_0: \alpha = 0$. Bai and Ng (2006) prove that if the factor loadings are not subject to time variation, $\hat{\delta}$ will indeed be asymptotically normal, regardless of the true value of $\alpha$, as long as $\sqrt{T/N} \to 0$. We expect that a similar result can be proved formally in our framework but leave this for future research. 4 Simulations 4.1 Design To illustrate our results and assess their finite sample validity we conduct a Monte Carlo simulation study. Stock and Watson (2002) assessed the performance of the principal components estimator when the factor loadings evolve as a random walk. We provide additional evidence on the necessary scale factor $h_{NT}$ for the random walk case (our Example 2). Second, we consider a different design in which a subset of the series undergo one large break in their factor loadings (an analog of Example 3). The design follows Stock and Watson (2002) where possible: $$X_{it} = \lambda'_{it} F_t + e_{it},$$ $$F_{tp} = \rho F_{t-1,p} + u_{tp},$$ $$(1 - aL)e_{it} = v_{it},$$ $$y_{t+1} = \sum_{q=1}^{r} F_{tq} + \varepsilon_{t+1},$$ $$13$$ where \(i = 1, \ldots, N, t = 1, \ldots, T, p = 1, \ldots, r\), and the variables \(\{u_{itp}\}, \{v_{it}\}\) and \(\{\varepsilon_{t+1}\}\) are mutually independent i.i.d. standard normally distributed. The scalar \(\rho\) is the common AR(1) coefficient for the \(r\) factors, while \(a\) is the AR(1) coefficient for the idiosyncratic errors.\(^4\) The initial values \(F_0\) and \(e_0\) for the factors and idiosyncratic errors are drawn from their respective stationary distributions. The initial factor loading matrix \(\Lambda_0\) was chosen based on the population \(R^2\) for the regression of \(X_{i0} = \lambda_{i0}F_0 + e_{i0}\) on \(F_0\). Specifically, for each \(i\) we draw a value \(R_i^2\) uniformly at random from the interval \([0,1,0,8]\). We then set \(\lambda_{i0p} = \lambda^*(R_i^2)\lambda_{i0j}\), where \(\lambda_{i0j}\) is i.i.d. standard normal and independent of all other disturbances. The scalar \(\lambda^*(R_i^2)\) is given by the value for which \(E[(\lambda_{i0}F_0)^2]/E[X_{i0}^2] = R_i^2\), given the draw of \(R_i^2\).\(^5\) We consider two different specifications for the evolution of factor weights over time. In the random walk model we set \[ \lambda_{itp} = \lambda_{i,t-1,p} + cT^{-3/4}\zeta_{itp}, \] \(i = 1, \ldots, N, t = 1, \ldots, T, p = 1, \ldots, r\), where \(c\) is a constant and the innovations \(\zeta_{itp}\) are i.i.d. standard normal and independent of all other disturbances. Note that the \(T^{3/4}\) rate is different from the rate of \(T\) used by Stock and Watson (2002). We consider the choices \(c = 0, 2, 5\) for our benchmark simulation. Observe that the standard deviation of \(\lambda_{iTp} - \lambda_{i0p}\) is \(cT^{-1/4}\), which for \(T = 100\) and \(c = 2\) equals 0.63, of the same magnitude as the standard deviation of \(\lambda_{i0p}\) (e.g., for \(a = \rho = 0\) and \(r = 5\), we have \(\lambda^*(0.45) = 0.40\). In the large break model, we select a subset \(J\) of size \([bN^{1/2}]\) from the integers \(\{1, \ldots, N\}\), where \(b\) is a constant. For \(i \notin J\), we simply let \(\lambda_{itp} = \lambda_{i0p}\) for all \(t\). For \(i \in J\), we set \[ \lambda_{itp} = \begin{cases} \lambda_{i0p} & \text{for } t \leq [0.5T] \\ \lambda_{i0p} + \Delta_p & \text{for } t > [0.5T] \end{cases} \] The shift \(\Delta_p\) (which is the same for all \(i \in J\)) is distributed \(\mathcal{N}(0, [\lambda^*(0.45)]^2)\), i.i.d. across \(p = 1, \ldots, r\), so that the shift is of the same magnitude as the initial loading \(\lambda_{i0p}\).\(^6\) We set \(b = 0, 4, 8\) in the benchmark simulations. --- \(^4\)We do not consider cross-sectional correlation of the idiosyncratic errors here. \(^5\)In this paper we have assumed that \(\Lambda_0\) is fixed for simplicity. It is not difficult to verify that \(\Lambda_0\) could instead be random, provided that it is independent of all other random variables, \(N^{-1}\Lambda_0\Lambda_0 \overset{D}{\rightarrow} D\) for an \(r \times r\) non-singular matrix \(D\), and \(E\|\lambda_i\|^4 < M\), as in Bai and Ng (2006). \(^6\)This shift process satisfies Assumption 4 by essentially the same argument as was used for the deterministic break in Example 3. Table 1: Combinations of $T$ and $N$ used in the simulations. <table> <thead> <tr> <th>$T$</th> <th>50</th> <th>100</th> <th>150</th> <th>200</th> <th>250</th> <th>300</th> <th>350</th> <th>400</th> </tr> </thead> <tbody> <tr> <td>$N$</td> <td>125</td> <td>250</td> <td>375</td> <td>500</td> <td>625</td> <td>750</td> <td>875</td> <td>1000</td> </tr> <tr> <td>$N^{-1/2}$</td> <td>0.089</td> <td>0.063</td> <td>0.052</td> <td>0.045</td> <td>0.040</td> <td>0.037</td> <td>0.034</td> <td>0.032</td> </tr> </tbody> </table> The free parameters are $T$, $N$, $r$, $\rho$, $a$, $b$, $c$. We let $r = 5$ throughout and focus on sample sizes $T = 50, 100, 150, \ldots, 400$. We set $N = [dT]$, with $d = 2.5$ as in the baseline design of Stock and Watson (2002). Table 1 shows the $(T, N)$ combinations. Because the fraction of series that undergo a shift in the large break model is $bN^{1/2}/N \approx bN^{-1/2}$, the table also lists values of $N^{-1/2}$. For example, for $T = 100$, $N = 250$ and $b = 4$, about 25% of the series undergo a large structural break in their factor loadings. We use the principal components estimator $\hat{F}$ described earlier to estimate the factors, assuming that the true number of factors $r$ is known. To evaluate the estimator's performance, we compute a trace $R^2$ statistic for the multivariate regression of $\hat{F}$ onto $F$, $$R^2_{\hat{F}, F} = \frac{\hat{E} \| P_F \hat{F} \|^2}{\hat{E} \| F \|^2},$$ where $\hat{E}$ denotes averaging over Monte Carlo repetitions and the projection matrix $P_F = F(F'F)^{-1}F'$. Corollary 1 states that this measure tends to 1 as $T \to \infty$. In each repetition we compute the feasible out-of-sample forecast $\hat{y}_{T+1|T} = \hat{\delta}' \hat{F}$, where $\hat{\delta}$ are the OLS coefficients in the regression of $y_{t+1}$ onto $\hat{F}_t$ for $t \leq T - 1$, as well as the infeasible forecast $\tilde{y}_{T+1|T} = \tilde{\delta}' F$, where $\tilde{\delta}$ is obtained by regressing $y_{t+1}$ onto the true factors $F_t$, $t \leq T - 1$. The closeness of the feasible and infeasible forecasts is measured by the statistic $$S_{\bar{y}, \hat{y}}^2 = 1 - \frac{\hat{E}(\hat{y}_{T+1|T} - \tilde{y}_{T+1|T})^2}{\hat{E}(\hat{y}_{T+1|T}^2)}.$$ the $R^2_{F,F}$ statistic as a function of the sample size $T$, for the three different choices of $c$ or $b$. Similarly, the bottom panel shows the $S^2_{y,y}$ statistic. Figure 1 confirms that substantial random walk variation in the factor loadings, vanishing at rate $T^{3/4}$, does impact the precision of the principal components estimator, but the performance improves as $T$ increases, as suggested by Corollary 1. Both in terms of closeness of factor spaces and out-of-sample forecasts, setting $c = 2$ impacts the performance to about the same extent as introducing moderate serial correlation in the idiosyncratic errors (Stock and Watson, 2002, cf.). The $c = 5$ simulations give much worse results; however, $c = 5$ is extreme in sense that the time variation in the factor loadings is of larger magnitude than the initial loadings for the choices of $T$ that we consider here. In Figure 2 we observe that the principal components estimator is also fairly robust to one-time, correlated large breaks. In fact, the feasible out-of-sample forecast is very close to the infeasible one, even when the sample size is small and about 50% of the series undergo a large shift in their factor loadings. The results for $a = \rho = 0.5$ are very similar to the ones depicted in Figures 1–2. Because there does not appear to be any interesting interactions between serial dependence and time variation, we do not report the alternative simulations. 4.3 Rate of convergence We now turn to the more detailed asymptotic rates stated in Theorem 1. Our method of proof suggests that it may not in general be possible to improve upon the $R_{NT}$ rate. To investigate this claim, we carry out two exercises. First, we execute a separate set of simulations in which $\lambda_{itp} - \lambda_{i,t-1,p} = cT^{-1/2}\zeta_{itp}$ for the random walk model, and the number of shifting series in the large break model is set to $[bN]$. These two rates both (just) violate the conditions for mean square consistency in Theorem 1. To make the results comparable to Figures 1–2, we scale down our choices of $b$ and $c$ so that the standard deviation of the random walk innovations and the number of shifting series approximately match at $T = 100$ under the two $(T, N)$ sequences. All other parameter choices are unchanged. See Figures 3–4 for the results. As hypothesized, for both models the trace $R^2$ statistic does not seem to improve systematically with the sample size. Second, we construct a “rate frontier” that corresponds to the predictions of Theorem 1 for the special case of the random walk model. To this end, suppose we set $N = [T^\rho]$ and $h_{NT} = cT^{-\gamma}$. Using the formula for $R_{NT}$ and the random walk calculations in Section 2.4, we obtain \[ R_{NT} = O\left( \max\{ T^{-1}, T^{-\mu}, T^{1-2\gamma-\mu}, T^{2-4\gamma} \} \right) = O(T^{m(\mu,\gamma)}), \] where \[ m(\mu, \gamma) = \max\{-1, -\mu, 1 - 2\gamma - \mu, 2 - 4\gamma\}. \] This convergence rate exponent reflects the influence of the magnitude of the random walk deviations, as measured by \( \gamma \), and the relative sizes of the cross-sectional and time dimensions, as measured by \( \mu \). Evidently, increasing the number of available series relative to the sample size improves the convergence rate, but only up to a point. In the following we set \( \mu = 1 \) as in the previous simulations. Denote \[ m(\gamma) = m(1, \gamma) = \max\{-1, -2\gamma, 2 - 4\gamma\} = \max\{-1, 2 - 4\gamma\}. \] We see that the dependence of the convergence rate on \( \gamma \) is monotonic, as expected, but nonlinear. The flat profile of the trace \( R^2 \) statistic in Figure 3 is fully consistent with \( m(1/2) = 0 \). These calculations have been carried out on the worst-case rate stated in Theorem 1. We have not been able to prove that the convergence rate \( R_{NT} \) is sharp, in the sense that there exists a DFM satisfying Assumptions 1–5 that achieves the \( R_{NT} \) rate. Instead, we provide simulation evidence suggesting that the independent random walk model (Example 2) achieves the stated bound. We maintain the simulation design described in Section 4.1 with \( a = \rho = 0 \) and \( N = \lfloor 2.5T \rfloor \), except that we set \( h_{NT} = 5T^{-\gamma} \) and vary \( \gamma \) over the range 0.25, 0.30, 0.35, ..., 1.50. For each value of \( \gamma \) and each sample size \( T = 100, 200, 300, \ldots, 700 \) we compute the statistic \[ \hat{\text{MSE}}(\gamma, T) = T^{-1}( \hat{E}\|\hat{F}\|^2 - \hat{E}\|P_F\hat{F}\|^2 ), \] where \( \hat{E} \) denotes the average over 500 Monte Carlo repetitions. This statistic is a close analog of the mean square error that is the object of study in Theorem 1. Our theoretical results suggest that \( \hat{\text{MSE}}(\gamma, T) \) should grow or decay at rate \( T^{m(\gamma)} \). We verify this by regressing, for each \( \gamma \), \[ \log \hat{\text{MSE}}(\gamma, T) = \text{constant} + m_\gamma \log T, \] using our seven observations \( T = 100, 200, \ldots, 700 \). Figure 5 plots the estimates \( \hat{m}_\gamma \) against \( \gamma \) along with the theoretical values \( m(\gamma) \). The estimated rate frontier is strikingly close to the theoretical one, although some finite-sample issues remain for intermediate values of \( \gamma \). This corroborates our conjecture that Theorem 1 provides sharp rates for the independent random walk case. 5 Discussion and conclusions The theoretical results of Section 3 and the simulation study of Section 4 point towards a considerable amount of robustness of the principal components estimator of the factors when the factor loading matrix varies over time. Although we have not proved that the consistency rate function presented in Section 4 is tight, inspection of our proof does not suggest any room for improvement and moreover the Monte Carlo estimate of the rate function accords broadly with the theoretical rate function. This leads us to suspect that the rate function is tight, and in this sense represents an upper bound on the parameter instability that can be tolerated by the principal components estimator. The amount of such instability is quite large when calibrated for values of \( N \) and \( T \) typically used in applied work. Our evidence concerning the robustness of the principal components estimator raise a tension with the results in Breitung and Eickmeier (2011), who in contrast suggest that undetected breaks in the factor loadings have the effect of increasing the dimension of the true factors. Indeed, we conjecture (but do not prove) that the principal components estimator will be consistent even under sequences of breaks for which the Breitung and Eickmeier (2011) test rejects. Pursuing this calculation would be of independent interest and would also return the large-dimensional discussion here to the bias-variance tradeoffs associated with ignoring breaks tackled in a low-dimensional setting by Pesaran and Timmermann (2005, 2007). A Proof To lighten the notation, we denote \( \sum_i = \sum_{i=1}^N \) (the same for \( j \)) and \( \sum_s = \sum_{s=1}^T \) (the same for \( t \)). A double sum \( \sum_{i=1}^N \sum_{j=1}^N \) is denoted \( \sum_{i,j} \). Proof of Theorem 1. We extend the proof of Theorem 1 in Bai and Ng (2002). By the definition of the estimator \( \hat{F}^k \), we have \( \hat{F}^k = (NT)^{-1}XX'\hat{F}^k \), where \( \hat{F}^k \) \( \hat{F}^k / T = I_k \) (Bai and Ng, 2008b). Define \( e = (e_1, \ldots, e_T)' \) and \( w = (w_1, \ldots, w_T)' \). Since \[ XX' = FN_0'\Lambda_0 F' + FN_0(e + w)' + (e + w)\Lambda_0 F' + (e + w)(e + w)', \] we can write \( \hat{F}^k - H^k F_t = (NT)^{-1} \{ \hat{F}^k FN_0'Ft + \hat{F}^k e \Lambda_0 F_t + \hat{F}^k e e_t + \hat{F}^k w \Lambda_0 F_t + \hat{F}^k w w_t + \hat{F}^k e w_t + \hat{F}^k w e_t \} \). Label the eight terms on the right-hand side \( A_{1t}, \ldots, A_{8t} \), respectively. By Loève’s inequality, \[ T^{-1} \sum_t ||\hat{F}^k - H^k F_t||^2 \leq 8 \sum_{n=1}^8 \left( T^{-1} \sum_t ||A_{nt}||^2 \right). \tag{5} \] Bai and Ng (2002) have shown that the terms corresponding to \( n = 1, 2, 3 \) are \( O_p(C_{NT}^{-2}) \) under Assumptions 1–3. We proceed to bound the remaining terms in probability. We have \[ ||A_{4t}||^2 \leq \left( T^{-1} \sum_s ||\hat{F}^k_s||^2 \right) \left( T^{-1} \sum_s ||F_s||^2 \right) ||N^{-1}\Lambda_0 w_t||^2. \] The first factor equals \( \text{tr}(\hat{F}^k \hat{F}^k / T) = \text{tr}(I_k) = k \). The second factor is \( O_p(1) \) by Assumption 1. Also, \[ E \left| \frac{\Lambda_0 w_t}{N} \right|^2 \leq N^{-2} \sum_{i,j} |E(w_{it}w_{jt})\lambda_{i0}'\lambda_{j0}| \leq \bar{\lambda}^2 h_{NT} N^{-2} \sum_{i,j} |E(\xi_{it}F_t\xi_{it}F_t)| \leq r^2 \bar{\lambda}^2 \sup_{p,q} h_{NT} N^{-2} \sum_{i,j} |E(\xi_{ipt}F_{tp}\xi_{itq}F_{tq})| = O(h_{NT}^2 N^{-2}Q_1(N, T)), \] 19 uniformly in $t$, by Assumption 4.1. Hence, $$ T^{-1} \sum_t \|A_{4t}\|^2 = O_p(h_{NT}^2 N^{-2} Q_1(N, T)). $$ Similarly, $$ \|A_{5t}\|^2 \leq \left(T^{-1} \sum_s \| ilde{F}_s^k\|^2\right) \left((N^2 T)^{-1} \sum_s (w_s' \Lambda_0 F_t)^2\right), $$ where the first term is $O(1)$ and $$ (N^2 T)^{-1} E \sum_s (w_s' \Lambda_0 F_t)^2 \leq (N^2 T)^{-1} \sum_s \sum_{i,j} |E(w_{is} w_{js} \Lambda_0 F_t \Lambda_0 F_t)| $$ $$ \leq r^4 \bar{A}^2 \sup_{p_1,q_1,p_2,q_2} h_{NT}^2 (N^2 T)^{-1} \sum_s \sum_{i,j} |E(\xi_{isp_1} \xi_{sq_1} F_{sp_1} F_{sq_1} F_{tp_2} F_{tq_2})|. $$ By summing over $t$, dividing by $T$ and using Assumption 4.2 we obtain $$ T^{-1} \sum_t \|A_{5t}\|^2 = O_p(h_{NT}^2 N^{-2} T^{-2} Q_2(N, T)). $$ For the sixth term, $$ E \|A_{6t}\|^2 \leq E \left\{ \left(T^{-1} \sum_s \| ilde{F}_s^k\|^2\right) \left((N^2 T)^{-1} \sum_s (w_s' w_t)^2\right)\right\} $$ $$ = k (N^2 T)^{-1} \sum_s \sum_{i,j} E(w_{is} w_{it} w_{js} w_{jt}) $$ $$ \leq k r^4 \sup_{p_1,q_1,p_2,q_2} \frac{h_{NT}^4}{N^2 T} \sum_s \sum_{i,j} |E(\xi_{isp_1} \cdots \xi_{jq_2} F_{sp_1} \cdots F_{tq_2})|, $$ where the last expectation contains the eight factors listed in Assumption 4.3. By Assumption 4.3, it follows that $$ T^{-1} \sum_t \|A_{6t}\|^2 = O_p(h_{NT}^4 N^{-2} T^{-2} Q_3(N, T)). $$ 20 Regarding the seventh term, using Assumption 5, \[ E\|A_7\|^2 \leq E \left( \left( T^{-1} \sum_s \|\tilde{F}_s\|^2 \right) \left( (N^2T)^{-1} \sum_s (e'_sw_t)^2 \right) \right) \] \[ = k(N^2T)^{-1} \sum_s \sum_{i,j} E(e_is)e_js E(w_{it}w_{jt}) \] \[ \leq k(N^2T)^{-1} \sum_s \sum_{i,j} (E(e^2_is)e^2_js)^{1/2} |E(w_{it}w_{jt})| \] \[ \leq kr^2M \sup_{p,q} h_{NT}^2 (N^2T)^{-1} \sum_s \sum_{i,j} |E(\xi_{itp}\xi_{jtq}F_{tp}F_{tq})| \] \[ = O(h_{NT}^2N^{-2}Q_1(N,T)), \] uniformly in \( t \). The second-to-last line uses \( E(e^2_{it}) \leq M \), whereas the last follows from Assumption 4.1. We conclude that \[ T^{-1} \sum_t \|A_{7t}\|^2 = O_p(h_{NT}^2N^{-2}Q_1(N,T)). \] A similar argument gives \[ T^{-1} \sum_t \|A_{8t}\|^2 = O_p(h_{NT}^2N^{-2}Q_1(N,T)). \] We conclude that the right-hand side of inequality (5) is the sum of variables of four different stochastic orders: \( O_p(C_{NT}^{-2}) \), \( O_p(h_{NT}^2N^{-2}Q_1(N,T)) \), \( O_p(h_{NT}^2N^{-2}T^{-2}Q_2(N,T)) \) and \( O_p(h_{NT}^2N^{-2}T^{-2}Q_3(N,T)) \). The statement of the theorem follows. \( \square \) References Figure 1: Simulation results for the random walk model, benchmark parameter and rate choices. Actual observations are marked with “x.” The lines are piecewise linear interpolations. Figure 2: Simulation results for the large break model, benchmark parameter and rate choices. Figure 3: Simulation results for the random walk model, alternative rates. Figure 4: Simulation results for the large break model, alternative rates. Figure 5: Rate frontiers for the random walk model with $N = O(T)$ and $h_{NT} = O(T^{-\gamma})$. The solid line interpolates between the finite-sample rate exponent estimates $\hat{m}_\gamma$ (observations are marked with “x”), while the dotted line represents the theoretical rate exponent $m(\gamma)$.
Australasian Journal of ArtsHealth Volume 1 2009 pp16 – 30 This article can be accessed online at http://www.newcastle.edu.au/research-centre/artshealth/journal/ http://www.nova.newcastle.edu.au ISSN 978-0-9805035-8-6 Memory, photography and the politics of abuse: The ambiguous nature of photography Dr Estelle Barrett School of Contemporary Arts Deakin University, Burwood Highway, Victoria, 3125 Australia Correspondence can be directed to the author via email ejbarret@deakin.edu.au Abstract Critical commentary on Australian artist Bill Henson’s work including the series Untitled 1994-1995 which represented Australia at the Venice Biennale is frequently framed within the discourse of the ‘white cube’. Its contextualisation in predominantly art historical and formalist perspectives tends to operate as a mechanism that denies affective and embodied dimensions of meaning making. Much the same could be said of the work of Marian Drew who uses road kill in her photographic still life works. However, the ‘distancing’ in these works is also achieved through historical allusion, which at the same time reactivates the flow of emotional empathy and desire. In this paper, I ask the question: “What distinguishes the work of these two artists with media images of torture?” My attempt to address this question will involve a narrative re-reading of selected works of Henson and Drew incorporating notions of affect, identification, memory and desire as processes which operate non-discursively, but which are inseparable from memory and lived experiences. This will permit a double exposure of the work of these artists. Within a psychoanalytical context, my re-reading will be used to extend an understanding of the now familiar press and Internet images of the torture of Iraqi prisoners. As a metaphor for desire and ideology, photography operates within manifest and latent registers. I will argue that certain forms of photographic practice may be understood in terms of a politics of abuse — instantiating an uneven differentiation of power between actants, the winning (forcefully or otherwise) of consent or complicity, the silencing of refusal of resistance and/or the incriminating of the ‘victim’ — whilst at the same time upholding the claim of verisimilitude and aesthetic or ethical intent. Critical engagement with such practices is crucial to an understanding of the relationship between institutional discourses, trauma and abuse in contemporary society. Keywords affect; memory; desire; trauma; photography. The ambiguous nature of photography The camera has been described by Roland Barthes as a visual clock in the service of memory recording and storing events as personal history, and by Susan Sontag, as a weapon of predatory activity. The ambiguity of photography lies in its claim to ‘truth’ in representing reality whilst at the same time operating as a metaphor for desire and fantasy. Louis Althusser’s theory of ideology (1971) suggests that ideologies and institutional discourses are also implicated in fantasy. Since the images to be discussed here derive their power and seduction from the ideologies and discourses that surround them, this double articulation or ambiguity is intensified permitting them to be viewed through the lens of what I term a “politics of abuse”. This operates through the following dynamics inherent in the viewing process: a fluid movement between manifest and latent meanings engendered by the images; the constantly shifting and interchangeable relationships between seduction and resistance that occurs at the point of reception, and the way this structures the victim/perpetrator and maker-addressor/ viewer- addressee positionalities that emerge both within the images and through the viewing process. My aim in this analysis of the photographic works of Bill Henson and Marion Drew and internet images of the torture of Iraqi prisoners at Abu Ghraib is to question conventional hierarchies that continue to influence debates about the potential uses and abuses of photography in art and the media. In doing so I hope to extend an understanding of the dynamics of trauma and abuse in contemporary society. Images are representations, and as such they are producers of ideology even as they evoke pleasure and allow us to articulate both conscious and unconscious or repressed desires. The question of who derives power and pleasure from images is related to issues of address and reception. Address relates to how images construct the subject as an idealised viewer who produces “preferred” readings; whereas reception refers to a potential or “real” viewer who may resist the interpolative power of the image and produce alternative or resistant readings. In many instances, institutionalised discourses — gallery catalogues, reviews and other commentaries operate as additional devices through which preferred readings are structured and endorsed. Hence, critical discourses as well as the context of viewing produce differential power relations between the addressor and addressee. This has certainly been the case for work of Bill Henson’s untitled series that represented Australia in the Venice Biennale of 1995. My reading of these works revolves around the way in which narrativity is implicated in the artist’s use of cinematic devices. It will also involve an application of what Mieke Bal has referred to as ‘visual rhetoric’ or the ambiguity of painterly texts, which engender the production of narrative meanings (Bal, 1991:93). It is an attempt to exercise what may be described an act of refusal, which requires becoming, ‘a resisting rather than an assenting reader’ (Felman, 1993:4). The narrative impetus in Henson’s work is often ignored in favour of formalist and art historical readings that tend to maintain a focus on the contexts of production of artworks rather than particularities of reception, and hence privilege a specified set of intertextual allusions over less predictable “intertextualities” that may arise when works are encountered by wider audiences. Ovid’s story of Tereus’ rape and subsequent silencing of Philomela by cutting off her tongue (Baldick et al: 1976) provides a useful springboard for understanding narrative structures that relate to Bal’s notion of visual rhetoric. This story is structured by a regime that incorporates the following features: an uneven differentiation of power between actants; the gaining (forcefully or otherwise) of consent or complicity; the silencing of dissent and the overpowering of resistance. Sandra Butler (1985) has observed a similar configuration in her analysis of child abuse, which she suggests, follows a pattern of unavoidable complicity, silencing, invalidating of resistance and/or incriminating of the victim. In Ovid’s myth, Philomela is unable to reveal that she is not guilty of adultery with her sister’s husband, because she is transformed into a songbird, whose melody, though sweet and eternal, renders actual events and characters “unrepresentable”. As Michel Foucault has observed, power can be viewed as the way in which certain actions modify others. Power seduces, it makes easier or more difficult; in the extreme it constrains or forbids absolutely (Foucault, 1981: 789). The ultimate deployment of this absolute or extreme form of power is physical force or violence, which has largely been superseded by disciplinary discourses and the way in which they are structured in society through mythologies and other institutional practices. This can be demonstrated in certain commentaries that surround Henson’s work. photographs with an analysis of violence in Rowan Wood’s film The Boys. In his review, Scheer’s acknowledgement of violence in these works, is juxtaposed, with reference to Hannah Arendt’s observation that violence appears when power is in jeopardy. In Scheer’s analysis, the textual shift from notions of violence as an attempt to regain power, to one of violence as a means of recuperating masculine identity is partially achieved through an appropriation out of context, of material from elsewhere — that is to say— the gaining of complicity of Arendt, an appeal to authority that confers power to the addressee. A deft movement in the commentary, from Wood’s film to Henson’s photographic works, completes the textual transcription by which violence discursively achieves the status of the sublime through its un-representability: “They [Henson’s photographic works] offer a perspective on violent death as that which cannot be represented” (Scheer, 1998: 29). The question of subjective agency is raised by the silencing mechanisms operating in discourses such as that in which Scheer’s review can be placed. Moreover, his use of “we” in commenting on what cannot be said of Henson’s images presumes a common perspective and a shared response with respect to the works he discusses. Later in this review, Scheer quotes Cioran: With age we grow accustomed to our terrors, no longer willing to do anything to break away from them, we make ourselves at home in the abyss. (Scheer, 1998: 29) The context of the gallery together with the technical processes involved in making images and the discourses that surround the images constitute a scopic regime or a field in which certain forms of power operate to produce prescribed modes of seeing whilst negating other modes of perception. There is a thematic resonance here, with Jill Bennett’s account of trauma imagery in art. Bennett suggests that in its dematerialised and sublimated form, trauma becomes a set of psychic functions and is not part of experience except in an abstract sense. For Bennett, the artist’s appropriation of trauma as psychic function operates as a distancing device allowing sensation to be cut off from the specificities of character and narrative action. Trauma, or the sensations related to trauma are hence to be put to equipmental use by the artist in order to trigger a more distanced empathetic vision as opposed forms of empathy that might be triggered in identificatory processes evoked through narrative elements. Bennett’s account moves us away from the idea of art as an interpersonal transmission of experience (of trauma), to one of art as a process that gives rise to critical reflection about trauma. (Bennett, 2006:7). This form of theoretical abstraction detracts from acknowledging that affect and sensation are tied to real bodies and particular histories. Moreover, as Bal (1995) has aptly demonstrated in her account of word/image relationships, the viewing of images inevitably gives rise to narrative meaning, which in turn is apprehended in relation to particular memories and histories of a material and sentient viewer. This blind spot of theoretical abstraction can be seen to operate in primarily formalist and art historical discourses surrounding Henson’s works. Such discourses have had a tendency to negate alternative interpretations through what Bal has elaborated as the framing or reframing of images through a “retelling” by a specific material viewer, that can realise meanings not accessible before the reframing (Bal, 1996:32). Bal shows us that a process of narrative production occurs in the viewing of visual images. Visuality, imagination and identification intertwine in the act of viewing to produce what Bal refers to as visual storytelling that emerges in relation to the viewer’s own memory and experience. It relates to situated meanings that emerge at the point of reception and is concerned with the question, not only of who is doing the “speaking” but also with the differential and particular meanings, affects and sensations produced by those who “hear”. Henson’s works from the series named Untitled represented Australia at the Venice Biennale in 1995. The exhibition in question consists of over a dozen massive photographic images (most of them 200.1 x 244.5 cm) depicting a twilight forest scene of abandoned cars. Gamin-like, naked figures inhabit the twilight landscape: two deathly figures entwine ambiguously in acts of violence or sex; a female figure is dragged naked by the hair; another lies — legs akimbo with what appears to be blood splattered between her thighs, her neck in an unnaturally twisted position suggestive of violent death. However, the contextualisation of these images in the rarefied locations of major galleries acts immediately to constrain and shape what can be said about them. Brian O’Doherty (1986) has described the phenomenon of the Gallery as ‘white cube’. The gallery is a white, ideal space which subtracts from the art work any cues that interfere with the fact that it is “art” and separates the work from anything that would detract form the work’s own evaluation of itself. The gallery exudes the sanctity of the church and the formality of the courtroom tending to construct the spectator as a disembodied eye, a faculty that relates exclusively to formal visual means and is immersed only in those ideas surrounding the work that have been circulated via critical discourses sanctioned by the institution. “It censors out the world of social variation, promoting a sense of the sole reality of its own point of view, and, consequently its endurance or eternal rightness” (McEvilley, 1986:9). Let us look at some of the comments that have constructed such a point of view with regard to Henson’s work. Isobel Crombie in the gallery brochure comments: Bill Henson beguiles his audience with images that are of a confronting, but strangely beautiful world.... His photographs are curiously non-intrusive... Henson’s figures remain both anonymous and essentially inviolate apparently acting according to their own desires and needs...The ritualistic appearance of their activities is not violent; there is a sensual slowness to what is happening that makes it more like a dream experience... (Crombie, 1995: 9) If the reader is confronted with a conception of death as the ultimate dream experience; a question that arises is “Who is doing the dreaming and to what realities might the dreamer(s) awake?” Henson himself has stated that, in as much as the figures remain apart from any specific identity, they belong to a dream or fantasy world and remain essentially inviolate (Henson, 1995). The separation of these works from lived reality is achieved through distancing discourses that negate the manifest visual rhetoric of the works. His collage technique of tearing the paper has been described as the trace of the artists labour “marking the force of the unrepresentable” (Scheer, 1998: 29), or as a formal element of composition, “punctuation points dividing the planes of the pictures “ (Crombie, 1996: 13). In the Biennale Catalogue (1995), Crombie devotes a great deal of space to the discussion of technique and formal elements in the works, to Henson’s careful eye for composition, which, she suggests, produces a “satisfying unity between the various components of the overall work” (Crombie, 1995:13). Then, there is mention of Classical and Romantic allusions, which combine to produce a sense of “otherworldly creatures” (Crombie, 1995:14). Landscape and figures have similarly been read with reference to a long line of Renaissance and post-Renaissance ‘masters’. If there is any story in such accounts, it is that of the artist’s heroic progress through the history of art. Taken to its logical conclusion, Crombie’s focus on formal elements reduces realistic representations of the human form to patches of colour or the abstracted chiaroscuro effects of shadow and light. The body in this context is transformed into, or becomes continuous with the landscape that surrounds it, a terra nullius to be mastered and emptied of any landmarks that may distinguish it in terms of a specific time and place or of an historical identity prior to its incorporation in the artist’s vision. The manifest content of this critical discourse works to negate or repress latent meanings that a narrative reading would allow. And yet there are those who feel assaulted by these images. Indeed my own initial engagement with them evoked a violent nausea and an involuntary outrage similar to that experienced in my first reading of the tale of Philomela. It would seem that these works are affective and affecting in ways that go beyond what is made available in the critical accounts discussed and what lies beneath the intentional structuring of the work in relation to prior artistic practices. Sontag rightly observes that the sanctity of photographs is derived from a continuing sense that they are indexes of the people they represent. This is evidenced the way in which there is a reluctance to discard or destroy them. If one applies the formalist approach to the catalogue image (Number 12) where the tearing or cutting of the paper extends from the figure’s pelvic bone and across the pubic region, the sense of sexual violation and amputation realised through the precise positioning of the cut or tear are rendered inadmissible. And yet the rhetoric of the image is insistent in its production of this recognition of violence—highlighting the blind spot of formalism in its refusal to admit that the reading of images is seldom free of experiential and social contexts. Let me turn now from the content of the images, to the curatorial process involved in the staging of this exhibition in 1997 at the Lawrence Wilson Gallery in Perth, where I first encountered Henson’s works. In order to access the exhibition, viewers were required to pass through a black-curtained entry similar to that found at the entrance of a peep show or cinema auditorium. In retrospect I am able to note the ease with which the first act of complicity was won. (I remember too, that there were no warnings signs outside—such as those that were placed at the entrance to Robert Mapplethorpe’s exhibition at The Art Gallery of Western Australia some months earlier. Inside the gallery it is dark. The only available light appears to be emitted by the works themselves drawing the viewer closer in order to decipher the images, and then directing the viewer around the walls from image to image. The viewing space is structured like a cinema auditorium producing an illusion of what Laura Mulvey has described as voyeuristic separation (Mulvey, 1981:208). The darkness separates the audience from the screen and from other viewers producing a sense of self-contained voyeuristic pleasure. Paradoxically, there is a temporary loss of ego in the fantasy of the film, and at the same time, a construction of ego ideals via identification. This identification involves the ego’s desire to fantasise itself in a certain active manner—sometimes involving cross-gendered identification—or else it may involve the desire to be desired. Henson’s setting up of the exhibition in such a manner may be read as an additional means of evoking a sense of separation of the works from lived reality; of placing it within the self-referential dream world of the images and their formalist concerns. However the structure of the viewing space also triggers a narrative impetus, which implicates desire and identification in the act of viewing. The need to accustom one’s eyes to the darkness means that one finds oneself very close to the images before being able to make out any detail. Further complicity is thus unavoidable. A story unfolds. In true Proppian fashion, the female forms are passive, being done to, having been done to; the male forms are active, doing, moving in the frame, and from frame to frame, finding something else to do, someone else to do it to. The forest in twilight is reminiscent of scenes in the movie Mad Max and reports of grisly acts of murder in the Nangarra forest on the outskirts of Perth; but the catalogue insists that these images have no connection with any reality. This permits the work to operate through the illusion of what Donna Haraway once described as the ‘god trick’—the presentation of a view from nowhere or from everywhere—which in either case amounts to claims of possessing ‘the power to see and not be seen, to represent while escaping representation’ (Haraway, 1991:188) On viewing the works, one is initially struck by the sheer scale and sublimity of the landscape backdrops, but as the figures emerge sensation and memory produce an abjection that (in my case) results in gagging. Alice Miller in Banished Knowledge (1990:55) tells us how Freud’s theory of infantile sexuality recast patient’s reports on sexual abuse as sheer fantasies attributable to their instinctual wishes. Is it possible (beyond hysteria) that there is some connection between Freudian discourse and the discourse of the white cube as it is revealed through the staging of these works? How might audiences not trained in art theory and history view them? Jill Bennett argues against Geoffrey Hartman’s view that images of violence have the capacity to engender secondary trauma. She suggests that the notion of images returning viewers directly to the scene of trauma are inadmissible in films and artworks, since artistic images are not re-presentations of real events. Hence according to Bennett, the shock engendered by graphic images is registered by a “third party” or “disinterested viewer”. This is the shock of art that leads to critical thought rather than “crude emotionalism”. (Bennett, 2005). Two points relating to aesthetic experience and trauma counter this notion of disinterestedness. In aesthetic experience, affective responses result not in a sense of separation, but in dissolution of self; self and other become co-extensive and this is the basis for identification, which involves a return to the ego and to language. The sign is continually remade at the borderline of the psyche and the outside world, and the image is determined by whose image it is, that is, for whom it signifies. However, in cases of extreme shock or trauma, there is an inability to access the language and distance required for identification to take place or for critical thought to take hold. That this can and does occur in some encounters with images indicates there is no “third party”— the viewer is returned to the “other” as self— to the scene of primary trauma (This may be more clearly understood in relation to Julia Kristeva’s account of to abjection in Julia Kristeva, 1982, Powers of Horror: An Essay on Abjection, trans. Leon S. Roudiez, New York: Columbia University Press.). Such an understanding of the dynamics of viewing does not imply the need for censorship of art, but for a more nuanced understanding of the dynamics of censorship itself— particularly as it relates to debates and discourses surrounding trauma and abuse and the potential uses and abuses of images in art and the media. 2. Marian Drew Similarly to Henson’s 1995 series, Marian Drew’s photographic works from the 2003 Australiana Series are derived from installations of road kill animals which are arranged and photographed as still life images following the tradition of Romantic and Dutch still life or vanitas paintings. This appropriation contextualises the works within an historical tradition and is used as a device to structure the viewer’s engagement. The aesthetic seduction of Drew’s images from the 2003 Australiana series belies the works more macabre origins and its underlying ideological content. Wolfang Haug (1987) describes the aestheticisation of objects as a process that increases their desirability on the basis of appearance. The appearance or semblance of beauty of one thing can be separated aesthetically and attached to other things so that surface appearance becomes different to “real” appearance. This aestheticisation of objects stimulates human sensuousness and structures the viewer’s response. Such strategies are most commonly used in the advertising of commodities and achieved through the specific technical means of photography. The striking colours and pristine beauty of Drew’s works is a source of immediate aesthetic pleasure. What distinguishes these works from that of Henson is that they are not only desirable objects of beauty but also operate overtly, as bearers of ethical or ideological messages. The manifest message concerning pride mortality, and the ecstasy of death and decay locate the work in art historical and formalist discourses as mentioned above. However the viewer is drawn into the works, by the coloured surfaces and identification with familiar or domestic objects. It is only after the viewer’s acceptance of the invitation to look and take pleasure, that the animals in the images take form as nameable objects, as corpses. When this happens in the case of Drew’s work, one is not confronted with the abject but with the uncanny— something familiar has become dislocated and alienated by being made visible. (Freud 1955). The sightless eyes and twisted postures of the creatures render them passive and vulnerable, but also accusatory. The viewer is shifted from the place of looking (a private place) to the place of being looked at, which is also a movement from innocence to a sense of shame and fear. In terms of power, the dynamics involved in viewing are similar to “politics of abuse” that I have suggested characterises the deployment of power in photographic practices. The viewer is implicated in the fate of the animals, only after the pleasure of looking has been won. The issue of ‘gaze’ is pertinent here. Theories of the gaze have traditionally posited the spectator of images as having more power than the person or object being looked at. This notion is tied up with ideas concerning desire and agency. However, contemporary accounts derived from feminist theory and practice show that this does not always follow. The tables are turned where power is conferred on objects or persons within images, through the capacity to return the gaze. As has already been shown in relation to Henson’s images, other means of conferring power to objects being looked at include surrounding institutional discourses that bestow ‘invisible’ power to the addressee from sources outside of the spectator/image scenario. Drew’s subjects (the road kill animals) and hence her images, derive part of their power from the growing impact of environmental and conservation discourses which take them beyond the meanings of traditional still life images. This “non-diegetic” influence deployed through the photographic images, anchors the act of viewing within a broader social context. In Drew’s paintings, the animals depicted can be said to return the disciplinary gaze of discourse as well as the omnipotent gaze of the dead. There is a potential here not only for the spectator to be fascinated and/or subjugated by fear, but the images also evoke an ethical and empathetic response. Hence, a balance is maintained between the tensions of affective and critical engagement. The ambiguity of both Henson’s and Drew’s works may not only be understood in terms of unconscious fears and desires but also through an understanding of the sublime. Edmund Burke’s account of the sublime experience suggests that it is not evoked by beauty, but by fear. Whilst fear in Burke’s account was essentially understood as an external force, it could be argued that like trauma, it emanates from the physicality of the body. Emily Lutzker contends that in the aporia of postmodern living, the remaining fixed element of being is confirmed through the sublime experience, which is a reminder of the physicality of the body (Lutzker, 1999). In Drew’s work, the reminder of this physicality is aligned with the critical and social dimensions of the underlying message. A “traumatic” awakening that occurs on closer inspection, implicates the viewer in the death of the creatures represented in the images and at the same time, the viewer is placed in relation to death as a common fate of all living things. This structuring set up an ethical relationship between self and other. Affect or sensation in this instance, operates through an aesthetics that is also an attribution of value. 3. Images of Torture The publication of images of the torture of Iraqi prisoners in the mass media and the Internet places them in a much larger arena of spectatorship and within more varied and complex networks of discourses. My concern in turning to these images is again related to the way in which power is deployed through the addressee/addrssor relationship and how the dynamics of images and the discourses from which they emerge serve to seduce and then, to subjugate dissent by effacing a specific and material viewer. Paul Frosh suggests that photography is a constitutive type of visible action within the social world — “a manifest performance of the power to make visible” (Frosh, 2001:45) Its use in the media and public realm is related to the power and the right of the viewer to see: ‘Photography as the agent of public visibility must be seen to ‘serve’ the sovereign viewer, at which point the roles of the voyeur and the informed citizen combine’ (Frosh: 2001:50). In this context of mutual implication, it becomes difficult to conceive of a locatable resistant practice of viewing. The public’s right to information and to see is an aspect of what Guy Debord has described as the society of the spectacle promoted by technologies that blur public and private boundaries and where there is an assumption that individuals want to look (Frosh 2001:49). The web of practices and relationships of public image production produces viewers as mass consumers of images — a public realm of the citizen voyeurism where participation in civic life and looking and the personal and political are mutually entwined. Rosalind Krauss has noted that the family photograph is an instrument or agent of the collective fantasy, of family cohesion, ‘part of the theatre that the family constructs to convince itself that it is together and whole’ (Krauss, quoted in Marsh 2003: 86). It can be argued in the context of Frosh’s discussion that dissemination of images the Iraqi torture images operate similarly. We have learned from Foucault that power is most effective when it is invisible and unverifiable. However, power relations also have an immediate hold on the body — marking it, training it, investing it with desire, forcing it to carry out tasks, to perform ceremonies and to emit signs. This now applies at a macro level whether one is a producer or viewer of images. The photographs of tortured Iraqi prisoners operate not only through the inherent ambiguity of the photographic medium itself, but also through slippery relations of power and desire and the systems of repression these engender. The deployment of these images of torture exemplify the validation of certain kinds of institutional knowledge and power. They also operate as thinly disguised gratification of barely repressed desires of individuals who produce, disseminate and consume them. Within the context of current US regime and attitudes, and a general fascination with images of the violent and the macabre, it could be argued that there is no longer any real distinction between the workings of individual repressed desire and fantasy and regimes of social discourse. The repressed has not only returned, but is openly appropriated to justify political and other ends. These images may be said to be indirectly if not explicitly endorsed by the ‘axis of evil’ discourse which operates through both manifest and latent registers. Whether one subscribes to this discourse or not, the images themselves, and their mode of deployment constitute an open invitation for audiences to look. Because any position to be taken by the viewer must first involve an act of complicity of looking, the viewer is placed in a voyeuristic relation to the scenes that are presented. In the case of one Internet site, overt invitations to look imply an already won complicity or shared perspective: `torture [sic] Rape Pics - BEST SITE YOU GOT TO CHECK IT OUT!!! YOU WILL BE IMPRESSED & SHOCKED! Enter and Enjoy! Torture Rape Pics - Best Site. ... Torture Rape Pics Free Rape Wedding Pictures. ... torture-rape-pics.41pic.com/main.html - Similar pages Warning! take a look at you own risk ! Photos of the rape. An other one. ... www.rundom.com/karim2k/archives/001236.html - 10k - Cached - Similar pages In other cases the interpolative dynamic draws its power through a quasi appeal to authority revealed in apologies for blurring and cropping of photos and gratuitous descriptions of what has been censored in the images with respect to their broader publication. The viewer is entreated to enter on what manifestly presents as ideological or ethical pretext. However, the message’s focus with what has been repressed or omitted from the images reveals a latent voyeuristic impetus. The images below are from the original 60 Minutes II broadcast. CBS says that it has twelve of these photographs, though there are dozens more. Among them: The Army has photographs that show a detainee with wires attached to his genitals. Another shows a dog attacking an Iraqi prisoner. (Note: Blurring of the photos was done by CBS.) The images below are from the New Yorker’s website [here]. Be sure to read their article, “Torture at Abu Ghraib” by Seymour Hersh. (Note: Blurring of the photos was done by the New Yorker.) The images below are from the Washington Post’s website [here]. (Note: All photos except the top one were cropped by the Post, presumably to avoid display of genitals.) On entering the site, viewers are presented with some images that structurally resemble earlier genres of visual anthropology and travel photography. Others parody holiday snapshots in ways that trivialise and negate the violence that is represented. In the invitation to look set up by the interpersonal modality of address, the images function, as a form of orientalism, eliciting complicity through codes of dominance and subjugation that establish difference and fix categories of self and other. As such, they are intended to manipulate unconscious fantasies and fear. The victims in these images are not only deprived of sight and the power to return the gaze, in Freudian terms their hooded heads signify castration. Hence at both conscious and unconscious levels the images promote identification with the perpetrators. Hard-edged photography rather than the aestheticising and distancing qualities often used in art photography adds to impersonalisation and dehumanisation of the subjects depicted. The underlying dynamics of seduction operating here, rest on the claim of a direct relation to a shared reality into which the viewer is placed by the act of looking. In this analysis I have tried to show that images manipulate the addressor/addressee positions in differential relations of power (and voyeuristic pleasure). This is related to the dynamics of looking and contexts and discourses that surround viewing practices. In addition, the structuring of images through technical means works to control and limit the gaze of the viewer that determine power relations in ways that tend to privilege the addressor positionality. I suggest that an understanding of these dynamics underpins the ambiguity of photographic practices in both art and the media. These processes are also related to the ambiguity of photographic practices, which in some contexts, make them ready instruments of a politics of abuse. References Memory hole website, Iraqi Images: <http://www.thememoryhole.org/war/iraqis_tortured/>
Quantum non-locality co-exists with locality Armen E. Allahverdyan and Arshag Danageozian Yerevan Physics Institute, 2 Alikhanian Brothers street, Yerevan 0036, Armenia PACS 03.65.-w – Quantum mechanics PACS 03.67.-a – Quantum information Abstract – Quantum non-locality is normally defined via violations of Bell’s inequalities that exclude certain classical hidden variable theories from explaining quantum correlations. Another definition of non-locality refers to the wave-function collapse thereby one can prepare a quantum state from arbitrary far away. In both cases one can debate on whether non-locality is a real physical phenomenon, e.g. one can employ formulations of quantum mechanics that does not use collapse, or one can simply refrain from explaining quantum correlations via classical hidden variables. Here we point out that there is a non-local effect within quantum mechanics, i.e. without involving hidden variables or collapse. This effect is seen via imprecise (i.e. interval-valued) joint probability of two observables, which replaces the ill-defined notion of the precise joint probability for non-commuting observables. It is consistent with all requirements for the joint probability, e.g. those for commuting observables. The non-locality amounts to a fact that (in a two-particle system) the joint imprecise probability of non-commuting two-particle observables (i.e. tensor product of single-particle observables) does not factorize into single-particle contributions, even for uncorrelated states of the two-particle system. The factorization is recovered for a less precise (i.e. the one involving a wider interval) joint probability. This approach to non-locality reconciles it with locality, since the latter emerges as a less precise description. Physics holds signal locality thereby the state of an isolated system (particle) cannot be changed by manipulating other particles that interacted with it in the past. Attempts to make this notion stronger created a bunch of quantum concepts known as non-locality [1–3]. Two main aspects of non-locality were identified: (i) application of the projection postulate to an entangled subsystem that changes (steers) the state of another subsystem arbitrary far away [1]. (ii) Bell’s inequalities, their derivation and interpretation [1]. Despite of a huge effort devoted to the issue of non-locality, there is no general agreement on whether it really exists [5–9]. Indeed, (i) does depend on the specific interpretation adopted for quantum mechanics, e.g. it is present in the Copenhagen interpretation, but absent in the many-world interpretation [18] and in the consistent histories interpretation [9]. Note that the issue of collapse (i.e. what happens to the quantum system after measurement) is not a part of the quantum probability given by Born’s rule. The latter can and does apply for describing experiments without worrying about what happens after measurement. This is one reason why the attention in studying non-locality shifted to Bell’s inequalities that do not assume the collapse. Instead they focus on explaining quantum correlations via hidden variables, i.e. they assume structures that are additional with respect to quantum probability. Bell’s inequalities can be derived assuming that the hidden variables—in addition to signal locality—hold the outcome independence feature (frequently also called local causality) [2,4]. Alternatively, Bell’s inequality can be derived without hidden variables, but assuming that frequencies obtained via different non-commuting measurements can be embedded into a single Kolmogorovian space [10]. Another version of this condition is that several (more than two) non-commuting quantities do have a joint probability [4,5]. The joint-probability assumptions can be imposed also on a single quantum particle, where no space-separated sub-systems exist. This leads to single-particle Bell inequalities [11,12]. Then, experimental validation of the Bell inequalities show that those additional concepts do not apply to quantum mechanics. Is this the only meaning of non-locality that certain interpretations have a cost to pay, or that specific classic concepts do not apply? We aim to demonstrate non-locality within quantum mechanics without referring to hidden variables, imposed Kolmogorovian probability space or projection postulate (hence it does not depend on which interpretation one prescribes to). The core of this demonstration is that while two non-commuting projectors do not have a joint precise (i.e. usual) probability within quantum mecha- nics, they do have an imprecise (i.e. interval-valued) joint probability 1314. Then non-locality is seen in the fact that the imprecise joint probability operator calculated for tensor products of single-particle (local) observables does not reduce to a tensor product of single-particle operators. Hence the imprecise joint probability (calculated via the ordinary Born’s rule) does not reduce to a product of single-particle contributions, even if the state of two- particle system is not correlated. Our results achieve on the level of imprecise joint statistics what the previous results could not do on the level of precise joint proba- bility for non-commuting observables, since the latter does not exist. This approach reconciles non-locality with lo- cality, because the local (tensor-product based) imprecise joint probability appears to predict a wider interval: it is not less precise. We continue by recalling pertinent features of projectors (see 24 for an accessible review), and then the notion of quantum imprecise probability. **Projectors** are self-adjoint operators \( P \) with \( P^2 = P \). Any projector \( P \) in a Hilbert space \( \mathcal{H} \) bijectively relates to the sub-space \( \mathcal{S}_P \) of \( \mathcal{H} \): 24: \[ \mathcal{S}_P = \{ \psi \in \mathcal{H} : P|\psi\rangle = |\psi\rangle \}. \] Eigenvalues of \( P \) are 0 and/or 1, and it is a quantum analogue of the characteristic function for a classical set 25. Hence projectors define quantum probability: with a density matrix \( \rho \), the probability of finding the eigenvalue 1 of \( P \) is given by Born’s formula \( \text{tr}(\rho P) \). The simplest projectors are 0 and \( I \). For two projectors \( P \) and \( P' \) we define \[ P \geq P' \text{ means } \langle \psi | P - P' | \psi \rangle \geq 0 \text{ for any } |\psi\rangle. \] Now apply (2) with \( |\psi\rangle = |\psi_0\rangle \), where \( P|\psi_0\rangle = 0 \), and then with \( |\psi\rangle = |\psi_1\rangle \), where \( P'|\psi_1\rangle = |\psi_1\rangle \). Hence the eigenvalues of \( P \) and \( P' \) relate to each other leading to \[ PP' = P'P = P' \text{ if } P \geq P'. \] Projectors (generally non-commuting) support logical op- erations 25: negation \( P = I - P \), conjunction \( P \wedge Q \) (\( \mathcal{S}_{P \wedge Q} = \mathcal{S}_Q \cap \mathcal{S}_P \) contains only those vectors that belong to both \( \mathcal{S}_P \) and \( \mathcal{S}_Q \)), and disjunction \( P \vee Q \), where \( \mathcal{S}_{P \vee Q} \) contains all linear combinations of vectors from \( \mathcal{S}_P \) and from \( \mathcal{S}_Q \). There are alternative representations 25: \[ P \wedge Q = \text{max}_R \{ R | R^2 = R, R \leq P, R \leq Q \}, \] \[ P \vee Q = \text{min}_R \{ R | R^2 = R, R \geq P, R \geq Q \}, \] where the maximization and minimization go over projec- tors \( R \) 25. Indeed, if \( R \leq P \), and \( R \leq Q \) in \( \mathcal{S}_P \), then due to 13, \( S_R \) is a subspace of both \( S_P \) and \( S_Q \). The maximal such subspace is \( S_{P \wedge Q} \). Likewise, if \( R \geq P \), and \( R \geq Q \), then \( S_R \) has to contain both \( S_P \) and \( S_Q \). The smallest such subspace is \( S_{P \vee Q} \), because joining \( S_P \) and \( S_Q \) as sets does not result to a linear space. Now \( P \vee Q = 0 \) only if \( P = Q = 0 \), but \( P \wedge Q \) can be zero also for non-zero \( P \) and \( Q \); e.g. in \( \dim \mathcal{H} = 2 \), we have either \( P = Q \) or \( P \wedge Q = 0 \) (and then \( P \vee Q = I \)). The above three operations are related with each other and with a limiting process 25: \[ P \vee Q = (P^\perp \wedge Q^\perp)^\perp, \] \[ P \wedge Q = \lim_{n \to \infty} (PQ)^n. \] For \( [P, Q] \equiv PQ - QP = 0 \) we have from 35 the ordinary features of classical characteristic functions \[ P \wedge Q = PQ, \quad P \vee Q = P + Q - PQ. \] **Imprecise classical probability** generalizes the usual (precise) probabilities 1516: the measure of uncertain- ity for an event \( E \) is an interval \([\overline{p}(E), \underline{p}(E)]\), where \( 0 \leq \underline{p}(E) \leq \overline{p}(E) \) are called lower and upper probabili- ities, respectively. Now \( \overline{p}(E) \) (resp. \( 1 - \underline{p}(E) \)) is a mea- sure of a sure evidence in favor (resp. against) of \( E \). The event \( E \) is surely more probable than \( E' \), if \( \overline{p}(E) \geq \overline{p}(E') \). The usual probability is recovered for \( \overline{p}(E) = \underline{p}(E) \). Two different pairs \( [\overline{p}(E), \underline{p}(E)] \) and \( [\overline{p}(E'), \underline{p}(E')] \) can hold simultane- ously (i.e they are consistent) if \[ \overline{p}(E') \leq \overline{p}(E) \text{ and } \underline{p}(E) \geq \underline{p}(E'). \] Every probability is consistent with \( \overline{p}'(E) = 0 \), \( \underline{p}'(E) = 1 \). This non-informative situation is not described by the usual theory 15 that inadequately offers for it the homo- gegeneous probability 15. Now \( [\overline{p}(E), \underline{p}(E)] \) does not imply that there is an explicit (but possibly unknown) precise probability for \( E \) located in between \( \overline{p}(E) \) and \( \underline{p}(E) \). There are various imprecise classical probability mod- els 1620. They do have numerous applications e.g. in decision making and artificial intelligence 16. Some of them were applied phenomenologically for describing aspects of the Bell’s inequality 2124. The quantum impre- cise probability is to be sought independently, along the physical arguments. Below we recall how it is determined. **Imprecise quantum probability.** For two non- commuting projectors \( P \) and \( Q \) one looks for upper \( \overline{\rho}(P, Q) \) and lower \( \underline{\omega}(P, Q) \) non-negative probability operators. For a state with density matrix \( \rho \), the respective upper and lower probabilities are given by Born’s rule: \[ \overline{\rho}(P, Q) = \text{tr}(\rho \overline{\rho}(P, Q)), \quad \underline{\rho}(P, Q) = \text{tr}(\rho \underline{\omega}(P, Q)). \] The linearity of \( \overline{\rho} \) over \( \rho \) means that within the standard measurement theory \( \overline{\rho}(P, Q) \) \((\overline{\rho}(P, Q))\) can be determined via measuring Hermitian operator \( \overline{\rho}(P, Q) \) \((\overline{\rho}(P, Q))\) in a state with an unknown \( \rho \). The following requirements Quantum non-locality co-exists with locality And $PQP \leq \mathcal{P}(P, Q)$ follows from: $\mathcal{P}(P, Q) - PQP = \mathcal{P}(P, Q) - P\mathcal{P}(Q, P)P = \mathcal{P}(P, Q)(I - P) \geq 0$ recalling that $\mathcal{P}(P, Q), P = 0$. Eq. $\mathcal{P}(P, Q) - PQP$ can be deduced from $\mathcal{P}(P, Q)$ and $\mathcal{P}(P, Q)$, respectively: $$\sum_a \mathcal{P}(P, Q) \geq Q, \quad \sum_a \mathcal{P}(P, Q) \leq Q,$$ where $\sum_a P_a = I$. Hence $\mathcal{P}(P, Q)$ and $\mathcal{P}(P, Q)$ do not lead to additive probabilities: the additive marginalization can still be applied, but it leads to an upper bound $\sum_a \mathcal{P}(P, Q)$ (and lower bound $\sum_a \mathcal{P}(P, Q)$) for the correct marginal probability $\mathcal{P}(I, Q) = \mathcal{P}(I, Q)$; see $\mathcal{P}(P, Q)$. The correct marginals are calculated from $\mathcal{P}(P, Q)$ by taking $P = I$ or $Q = I$. Note that monotonocity does not hold, i.e. generally $\mathcal{P}(P, Q) \not\leq \mathcal{P}(I, Q)$, though $P \leq I$. Eq. $\mathcal{P}(P, Q) - PQP$ directly leads to $\mathcal{P}(P, Q)$, which follows from $\mathcal{P}(P, Q)$ and $\mathcal{P}(P, Q)$. Imprecise probability for combined systems. We now turn to applying the above formalism for two particles denoted by indices 1 and 2, living resp. in Hilbert spaces $\mathcal{H}_1$ and $\mathcal{H}_2$. Let $P_k$ and $Q_k$ be two generally non-commuting ($[P_k, Q_k] \neq 0$) projectors living in $\mathcal{H}_k$, $k = 1, 2$. This is the standard set-up for designing and studying Bell’s inequalities $[4]$. For two (non-identical) particles these projectors read $P_1 \otimes I, \quad Q_1 \otimes I, \quad I \otimes P_2, \quad I \otimes Q_2.$ Projectors refer to different particles naturally commute, e.g. $[P_1 \otimes I, I \otimes P_2] = 0$. Hence the joint feature is described by the projectors $P_1 \otimes I$ or $P_2 \otimes I$, which—being a tensor product of single-particle operators—can be measured separately in sub-systems (and then bringing the measurement data together). For factorized states, $\rho_1 \otimes \rho_2$, these measurements lead to uncorrelated probabilities. There are two ways (resp. $P_1 \otimes I$ and $P_2 \otimes I$) for looking at the joint statistics of two local operators: $$\omega(P_1 \otimes P_2, Q_1 \otimes Q_2), \quad \mathcal{P}(P_1 \otimes P_2, Q_1 \otimes Q_2); \quad (22)$$ $$\omega(P_1 \otimes Q_2, Q_1 \otimes P_2), \quad \mathcal{P}(P_1 \otimes Q_2, Q_1 \otimes P_2). \quad (23)$$ For the lower probability operators in $\mathcal{P}(P, Q)$, which leads to an intuitively expected outcome: $$\omega(P_1 \otimes P_2, Q_1 \otimes Q_2) = \omega(P_1, Q_1) \otimes \omega(P_2, Q_2) \quad (24)$$ $$= \omega(P_1 \otimes Q_2, Q_1 \otimes P_2). \quad (25)$$ The origin of $\mathcal{P}(P, Q) - PQP$ is understood from $\mathcal{P}(P, Q)$ and $\mathcal{P}(P, Q)$, i.e. $P \otimes Q$ and $P \otimes Q$ qualify as certain (resp.) lower and upper probability operators, while the factor $(P - Q)^2$ in $\mathcal{P}(P, Q)$ is needed to ensure $\mathcal{P}(P, Q)$. An important geometric feature of $\mathcal{P}(P, Q)$ is that both $PQP$ (i.e. the restriction of $Q$ into $S_P$) and $QPQ$ hold: $$\mathcal{P}(P, Q) - PQP, \quad PQP \leq \mathcal{P}(P, Q). \quad (18)$$ Now $\mathcal{P}(P, Q) - PQP$ is shown from $P \otimes Q \leq Q$ [see $\mathcal{P}(P, Q) = P(P \otimes Q)P \leq PQP$. $p$-3 Eq. (24) shows that the lower probability operator is tensor product of two local projectors. Eq. (25) confirms that two different ways (22) and (23) of combining commuting projectors leads to the same outcome. Hence the lower probability is local. The situation with the upper probability is different. Our main result (deduced in Appendix) is formulated simpler after joint block-diagonalization of $P_k$ and $Q_k$ (for each $k = 1, 2$) via a suitable unitary $U_k$ [cf. (20)]. This is known as the CS-representation (24–29): $$ P_k = \text{dg}([P_{k_2}^{[m_k]}, I^{[m_k(1)]}, 0^{[m_k(2)]}, I^{[m_k(3)]}, 0^{[m_k(4)]}], (26) $$ $$ Q_k = \text{dg}([Q_{k_2}^{[m_k]}, I^{[m_k(1)]}, 0^{[m_k(2)]}, I^{[m_k(3)]}, 0^{[m_k(4)]}], (27) $$ where $\text{dg}[A, B, ...]$ means block-diagonal matrix with block $A, B, ...$. Upper indices are indicators that the dimension of each square block matrix, e.g. $I^{[m_k(2)]}$ means $m_k(2) \times m_k(2)$ unity matrix. We omit these indices, whenever their implications are clear from the context. According to (26) (27), the original Hilbert space $\mathcal{H}$ can be represented as a direct sum of subspaces with dimensions $2m_k, m_k(1), m_k(2), m_k(3)$ and $m_k(4)$. Some of them can be zero, i.e. the subspaces will be absent from (26) (27). We recall a possible explicit representation for the non-commuting parts $P_k$ and $Q_k$ of (resp.) $P_k$ and $Q_k$ as $2m_k \times 2m_k$ matrices (24–29): $$ P_k = \left( \begin{array}{cc} C_k^2 & C_k S_k \\ C_k S_k & S_k^2 \end{array} \right), \quad Q_k = \left( \begin{array}{cc} I & 0 \\ 0 & 0 \end{array} \right), (28) $$ where $C_k$ and $S_k$ are invertible, self-adjoint $m_k \times m_k$ matrices holding $$ C_k^2 + S_k^2 = I, \quad [C_k, S_k] = 0. (29) $$ The simplest example of (26) (29) are the projectors for $x$ and $z$-components of two spin-$\frac{1}{2}$ particles. Here dim$\mathcal{H}_k = 2$, only the subspace with $2m_k = 2$ is present, and $P_k = \frac{1}{2} (\sigma_x, 0), \quad Q_k = \frac{1}{2} (\sigma_z, 0)$, where $\sigma_x$ and $\sigma_z$ are the Pauli matrices. Hence $C_k = S_k = \frac{1}{\sqrt{2}}$ reduce to numbers. The following relations are deduced from (26) (29): $$ P_k \vee Q_k = I, \quad P_k \wedge Q_k = 0, \quad \text{tr} P_k = \text{tr} Q_k = m_k. (30) $$ Hence in all other subspaces besides $P_k \vee Q_k = I$ [cf. (20)], the projectors $P_k$ and $Q_k$ commute. In the representation (26) (27), the upper and lower probability operators (10) read via (30): $$ \omega(P_k, Q_k) = \text{dg}(I - (P_k - Q_k)^2, I, 0, 0, 0), (31) $$ $$ \omega(P_k, Q_k) = \text{dg}(0, I, 0, 0, 0). (32) $$ Here is our main result obtained within the CS representation (26) (27) (see Appendix): $$ \omega(P_1, Q_1) \otimes \omega(P_2, Q_2) - \omega(P_1 \otimes P_2, Q_1 \otimes Q_2) \geq 0, (34) $$ where other 24 blocks nullify, and the inequality follows from the definition (16) of $\omega$. Eq. (34) shows that the upper probability operator $\omega(P_1 \otimes P_2, Q_1 \otimes Q_2)$ does not reduce to the tensor product $\omega(P_1, Q_1) \otimes \omega(P_2, Q_2)$, i.e. it does not have the local form. We take this as indications of non-locality. This feature is stronger than the notion of entanglement, since it is formulated without density matrices, i.e. on the level of probability operators. Now $\omega(P_1 \otimes P_2, Q_1 \otimes Q_2) = \omega(P_1, Q_1) \otimes \omega(P_2, Q_2)$ is recovered whenever at least one pair commutes, i.e. either $[P_1, Q_1] = 0$ or $[P_2, Q_2] = 0$ holds; e.g. $[P_1, Q_1] = 0$ implies that $P_1$ and $Q_1$ are absent from (34). Hence $\omega(P_1 \otimes P_2, Q_1 \otimes Q_2) \neq \omega(P_1, Q_1) \otimes \omega(P_2, Q_2)$ is due to non-commutativity at both 1 and 2. In particular, we get (as we should) the correct marginal upper probability $\omega(P_1, Q_1) \otimes I$ for the particle 1 whenever $P_2 = Q_2 = I$. The inequality in (34) means that the local form $\omega(P_1, Q_1) \otimes \omega(P_2, Q_2)$ of the upper probability is less precise than the non-local expression $\omega(P_1 \otimes P_2, Q_1 \otimes Q_2)$, i.e. upper probabilities calculated via $\text{tr}(\rho \omega(P_1, Q_1) \otimes \omega(P_2, Q_2))$ (will for an arbitrary density matrix) be larger than those calculated $\text{tr}(\rho \omega(P_1 \otimes P_2, Q_1 \otimes Q_2))$. In this sense, the imprecise probability reconciles locality with non-locality. Eqs. (31) and (28) (29) imply $$ \omega(P_1 \otimes Q_2, Q_1 \otimes P_2) - \omega(P_1 \otimes P_2, Q_1 \otimes Q_2) \neq 0. (35) $$ Hence depending on how we combine commuting projectors—via (22) or (23)—we shall get different upper probability operators. This clearly contrasts with features (24) (26) of the lower probability operator. As seen below, (35) is generally non-zero even if we calculate the upper probabilities for independent subsystems, i.e. via tensor-product states $\rho = \rho_1 \otimes \rho_2$. Two spin-1/2 particles. We now illustrate (34) (35) via a pair of spin-1/2 particles, where $m_k = 1$ in (26) (29), and also $m_k(1) = m_k(2) = m_k(3) = m_k(4) = 0$ for $k = 1, 2$. For simplicity we also assume $P_1 = P_2 = P$ and $Q_1 = Q_2 = Q$ (the index $k$ drops out), and $C_k = S_k = 1/\sqrt{2}$ in (28) (29), i.e. $P$ and $Q$ amount to $x$ and $z$ components of the spin $\frac{1}{2}$. In (35) we employ $P \vee Q = (P + Q)(P + Q)^{-1}$, where $X^-$ is the pseudo-inverse of matrix $X$ (31). We use definition (11) for the tensor product. The result reads from (34) or from (35): $$ \omega(P, Q) \otimes \omega(P, Q) - \omega(P \otimes P, Q \otimes Q) = \begin{pmatrix} 0 & 0 & 0 & 0 \\ 0 & 2 & -1 & -1 \\ 0 & -1 & 2 & -1 \\ 0 & -1 & -1 & 2 \end{pmatrix}, (36) $$ $$ \omega(P, Q) \otimes \omega(P, Q) - \omega(P \otimes Q, Q \otimes P) = \begin{pmatrix} 1 & -1 & -1 & 0 \\ -1 & 1 & 1 & 0 \\ -1 & 1 & 1 & 0 \\ 0 & 0 & 0 & 3 \end{pmatrix}. (37) $$ Now both (39) and (40) have the same eigenvalues: 0 and 1/4 (both doubly degenerate). However, they do not commute. Let us define the following separable state: \[ \rho \otimes \rho, \quad \rho = \begin{pmatrix} a & b e^{i\phi} \\ b e^{-i\phi} & 1 - a \end{pmatrix}, \] where \(\rho\) is a one-particle density matrix with real parameters \(a, b\) and \(\phi\) that hold \(1 \geq a \geq 0\) and \(a(1-a) \geq b^2\). These conditions ensure \(\rho \geq 0\). The difference between (37) and (39) is not zero even for separable states: \[ \text{tr} \left[ (\varpi(P \otimes P, Q \otimes Q) - \varpi(P \otimes Q, Q \otimes P)) \rho \otimes \rho \right] = \frac{1}{12} \left[ (1 - 2a)^2 + 4b^2 + 4b(1 - 2a) \cos(\phi) \right] \geq 0. \] For separable states (39) has a definite sign. No definite sign is possible for all states, since \(\text{tr} \left[ (\varpi(P \otimes P, Q \otimes Q) - \varpi(P \otimes Q, Q \otimes P)) \right] = 0\) due to the fact that \(\varpi(P \otimes P, Q \otimes Q)\) and \(\varpi(P \otimes Q, Q \otimes P)\) have the same eigenvalues. **Summary.** We studied the joint statistics of non-commuting observables shared between two particles. This is a standard set-up for defining quantum non-locality. Upon assuming the existence of joint probabilities for non-commuting observables (or alternatively, specific features of hidden variable theories), it leads to the Bell inequalities for certain (entangled) states [4]. However, the precise joint probability for non-commuting observables is denied by quantum mechanics [4, 14], restricting the non-commuting observables to inapplicability of certain non-quantum concepts to quantum mechanics. In contrast, we addressed the above set-up from the viewpoint of imprecise joint probability for non-commuting observables. This concept does exist: it is well-defined and holds all requirements asked by quantum mechanics from a joint probability. Our basic message is that for making more precise predictions for the joint probability of two-particle observables requires non-locality, because the corresponding upper probability is not a tensor product of one-particle factors. In contrast to other forms of quantum non-locality (e.g. the non-locality without entanglement [22]), the uncovered form of non-locality is formulated on the level of observables, i.e. independently from the notion of quantum states. Hence it survives for separable states, as we see for the simplest example. **Appendix.** For deriving (34), we introduce two different types of tensor products: \[ A \otimes B \quad \text{and} \quad A \bullet B = A \otimes B = B \otimes A, \] where \(A \otimes B\) is the usual from left-to-right tensor (Kronecker) product, e.g. when \(A\) is a 2 \(\times\) 2 matrix, \[ \begin{pmatrix} a_{11} & a_{12} \\ a_{21} & a_{22} \end{pmatrix} \otimes B = \begin{pmatrix} a_{11}B & a_{12}B \\ a_{21}B & a_{22}B \end{pmatrix}, \] where \(a_{ik}B\) (with \(i, k = 1, 2\)) means that a number \(a_{ik}\) is multiplied over all matrix elements of \(B\). We stress that \(A \otimes B\) and \(A \bullet B\) in (40) are related by a unitary operator that does not depend on \(A\) and \(B\). Now we note \[ dg(A, B) \otimes dg(C, D) = dg(U, V) \times \] \[ dg(A \otimes dg(C, D), B \otimes dg(C, D)) dg(U, V) \] \[ = dg(A \bullet dg(C, D), B \bullet dg(C, D)) \] \[ = dg(A \otimes C, A \bullet D, B \bullet C, B \bullet D), \] where when going from (32) to (33) we used (11), and where (44) is achieved from (43) by means of block-diagonal unitary matrices with blocks \(U\) and \(V\). Eq. (46) is a block-diagonal matrix that will be useful below. For \(A\) and \(B\) being projectors we get \[ dg(A, B) \wedge dg(C, D) = dg(A \wedge C, B \wedge D), \] \[ dg(A, B) \vee dg(C, D) = dg(A \vee C, B \vee D), \] where (46) is derived from (47), while (47) is deduced from (46) via (45). Eqs. (42–47) straightforwardly generalize to an arbitrary number of blocks. Now recall from (21) that \[ \varpi(P_1 \otimes P_2, Q_1 \otimes Q_2) = \varpi(P_1 \otimes P_2, Q_1 \otimes Q_2) \] \[ = P_1 \otimes P_2 \vee Q_1 \otimes Q_2 - (P_1 \otimes P_2 - Q_1 \otimes Q_2)^2 \] Using (42–45) and (46–47) we write down \[ P_1 \otimes P_2 = dg(\hat{P}_1 \bullet \hat{P}_2, \hat{P}_1, \hat{P}_2, \hat{P}_1, \hat{P}_2, 0, 0, \ldots) \] \[ Q_1 \otimes Q_2 = dg(\hat{Q}_1 \bullet \hat{Q}_2, \hat{Q}_1, \hat{Q}_2, \hat{Q}_1, \hat{Q}_2, 0, 0, \ldots) \] where for simplicity we write \(\hat{P}_1 \bullet I\) as \(\hat{P}_1\) and \(I \bullet I\) as \(I\), and where other 20 blocks (in each equation) were omitted for simplicity. Now both \(P_1 \otimes P_2 \vee Q_1 \otimes Q_2\) and \((P_1 \otimes P_2 - Q_1 \otimes Q_2)^2\) are easy to calculate, since they respect the block-diagonal structure; cf. (47). Here we, in particular, employ \((\hat{P}_1 \bullet I) \vee (\hat{Q}_1 \bullet I) = I \bullet I = I\); see the first equation in (30). Hence \[ \varpi(P_1, Q_1) \otimes \varpi(P_2, Q_2) = \] \[ dg((I - (\hat{P}_1 - \hat{Q}_1)^2) \bullet (I - (\hat{P}_2 - \hat{Q}_2)^2), \] \[ I - (\hat{P}_1 - \hat{Q}_1)^2, 0, 0, 0, \ldots) \] Employing (31) we work out in the same way \[ \varpi(P_1 \otimes P_2, Q_1 \otimes Q_2) - \varpi(P_1, Q_1) \otimes \varpi(P_2, Q_2) \] \[ = dg((\hat{P}_1 \bullet \hat{P}_2) \vee (\hat{Q}_1 \bullet \hat{Q}_2) - (\hat{P}_1 \bullet \hat{P}_2 - \hat{Q}_1 \bullet \hat{Q}_2)^2 \] \[ - (I - (\hat{P}_1 - \hat{Q}_1)^2) \bullet (I - (\hat{P}_2 - \hat{Q}_2)^2), 0, 0, 0, \ldots) \] where the last 24 blocks are zero. Once only one block is non-zero, we obtain \begin{align} \varpi(P_1 \otimes P_2, Q_1 \otimes Q_2) &= d\varpi((P_1 \otimes P_2) \perp (Q_1 \otimes Q_2) - (P_1 \otimes P_2 - Q_1 \otimes Q_2)^2 \\ &= - (I - (P_1 - Q_1)^2) \otimes (I - (P_2 - Q_2)^2), \quad 0, \ldots, 0. \quad (55) \end{align} Now (55) can be simplified by employing \begin{align} (P_1 \otimes Q_2) - (Q_1 \otimes P_2) &= I - (P_1 \otimes P_2 - Q_1 \otimes Q_2)^2 \\ &= (I - (P_1 - Q_1)^2) \otimes (I - (P_2 - Q_2)^2), \quad (56) \end{align} whence derivation is algebraically tedious, but straightforward. Below we shall prove that \begin{align} (P_1 \otimes P_2) \perp (Q_1 \otimes Q_2) + (P_1 \otimes Q_2 \perp Q_1) \perp (Q_1 \otimes P_2) &= I \quad (57) \end{align} Using (55, 57) in (55) finishes the proof of (54). The proof of (57) consists of three steps. First, we note that the two projectors in left-hand-side of (57) are orthogonal to each other thanks to \begin{align} (P_1 \otimes P_2)(P_1 \otimes Q_2) - (Q_1 \otimes P_2)(Q_1 \otimes Q_2) = 0, \quad (58) (P_1 \otimes P_2)(Q_1 \otimes P_2) - (Q_1 \otimes Q_2)(Q_1 \otimes P_2) &= 0. \quad (59) \end{align} Hence the left-hand-side of (57) is \( \leq I \). Second, we get using (60) \begin{align} (P_1 \otimes P_2) \perp (Q_1 \otimes Q_2) &= (P_1 \perp Q_1) \perp (P_2 \perp Q_2) \\ &= (P_1 \perp Q_2) \perp (Q_1 \perp P_2) = 0. \quad (60) \end{align} Third, recall that if \( S_P \) is the Hilbert space generated by a projector \( P \), then \( \dim[S_P] = trP \). Now apply to both sides of (57) the known formula [29] \begin{align} tr(P \lor Q) + tr(P \land Q) = tr(P) + tr(Q), \quad (61) \end{align} that holds for any projectors \([P,Q] \neq 0\), and use (58, 60): \begin{align} tr(P_1 \otimes P_2) &= tr(Q_1 \otimes Q_2) = m_1m_2, \quad (62) \end{align} \begin{align} tr((P_1 \otimes P_2) \lor (Q_1 \otimes Q_2)) &= tr((P_1 \otimes Q_2) \lor (Q_1 \otimes P_2)) = 2m_1m_2. \quad (63) \end{align} Eqs. (62, 63) show that the traces of both sides (=projectors) of (57) are equal. Hence (57) was proved. REFERENCES
What’s inside MySpace comments? Luisa Massari Dept. of Computer Science University of Pavia Pavia, Italy email: luisa.massari@unipv.it Abstract—The paper presents a characterization of the comments included in the user profiles of a popular social networking site. Some parameters are defined, which express comments composition in terms of length, language used, and external resources accessed. From the analysis of comments a model is derived, which reflects three different types of users. The behavior of users in terms of the language used is also derived. Index Terms—Social networks, comments, user profile characterization. I. INTRODUCTION Social networks are online environments that let users to build a personal profile page, including personal details and cultural interests, to publish various types of content, such as, pictures, email, videos, blogs, comments, and to establish connections with other users to enlarge friend circle. Communication modes usually differ from face to face interpersonal relationships. Comments, in particular, represent for social network users a sort of one-to-many communication: comments are messages posted in personal pages, and made visible to everyone or to friends only. Comments can include text, references to Web pages, animated objects or images. Hence, comments represent a rich source of information about users opinions, connections, and also a way for easily and rapidly advertising and disseminating information and content. The purpose of this study is to analyze and characterize the behavior of MySpace [1] users from the point of view of comments posted in their profile pages. MySpace has been chosen because of its popularity: even though Facebook leads social networking category, MySpace is still a top 10 website in the US. ComScore [2] reported 112 million unique US visitors for Facebook in December 2009, and 57 million for MySpace; 54% of all Internet users visited Facebook in December, and 27% visited MySpace [3]. Moreover, MySpace is one of the few social networking sites that allows to easily access to profile pages and retrieve data about users. Social networks have recently captured the interest of different areas. Many companies analyze social networks in order to understand what web users, and people in general, think about their brands, their product and their services. For the purpose, companies rely upon search engines or a few analysis systems that mine social network public profile pages for specific keywords. In the research community, many studies have focused their attention on the analysis of online social networks, on their contents and on users characteristics. The nature, the structure, and the evolution of social networks are examined in many recent paper (see, e.g. [4]–[7]). Some studies ([6]) use graphs to describe social networks structural properties and to provide measures on the proximity between groups of users. The impact of social networking services is addressed in [8], where authors show that the majority of collaborations among users results from the opportunities of interactions offered by the services available on the sites. Some papers have addressed the characterization of the technological aspects of the workload of social networking web sites, in particular of sites offering specific services, such as, YouTube for video-sharing ([9]–[12]), Wikipedia for the creation of the so called wikis [13], and blogs [14]. These studies outline the peculiarities of these new types of workloads compared with the characteristics of traditional web workloads. A few recent papers address specifically the analysis of comments as a form of interpersonal communications. In [15] a large number of MySpace profiles are analyzed, and demographic characteristics are derived, together with a model of the language used. In [16], [17], the characteristics of social network comments are investigated. English comments are considered, and characteristics, such as length and language features are analyzed, together with dialogs between pairs of friends. The analysis presented in this paper differs from previous work because of the large number of profiles considered and because, as far as we know, no study in the existing literature has approached the analysis of external resources accessed through comments and of the different languages used. In particular, our objective is to characterize the behavior of social networks users in terms of the type of language used in comments, of their length and of links to external resources. In Section II, we describe the data considered in this study and the methodology for their analysis. Section III presents results on user profile characterization, statistics on comments and on references to external resources. Moreover, the analysis of the words used in comments is presented. Finally, conclusions and future work are presented in Section IV. II. DATA SAMPLE A sample of 1.4 millions of public user profiles has been obtained by crawling, using the curl command line tool, the MySpace Web site [18]. These profiles contain about 369 millions of comments which have been analyzed to characterize the language used and the type of content published in MySpace profiles. As a first step, external links have been identified in comments, in order to analyze locations of the object’s data and Web resources. Remaining text has then been parsed and cleaned in order to remove special characters, HTML tags, punctuations, and to obtain a list of words. These words have been spell checked and valid words, that is, belonging to a dictionary, have been obtained. Most popular languages have been considered, namely, English, French, Italian, German, Spanish, Portuguese, and Dutch. Unrecognized words due to typos, or typical of the “Internet language” such as abbreviations, slang expressions exclamations have hence been identified. At the end of this process, each comment has been described by its length in terms of number of words, valid and non-valid, and number of characters, by the language used, and by the number and types of external references. More in detail, each comment has been identified by two ids: the id of the corresponding and the id of the user who added the comment. These identifiers are assigned to users when they register. The characteristics of the comment in terms of language composition, length, and external resources have then been expressed by means of 16 parameters, namely, the number of raw and clean characters, that is, before and after cleaning, the total number of words, the number of words belonging to one of 7 languages (English, French, Italian, German, Spanish, Portuguese and Dutch), the number of unrecognized words, the number of links to Web pages, to images and to animated objects, the number of emoticons and of exclamations, which we have defined as long sequences of punctuation characters. III. STATISTICS Comments are distributed across the user profiles as shown in Figure 1. The figure represents 62% of the profiles, containing up to 100 comments. About 11% of the total, namely 149,185 users, have just one comment in their page, and 6% have two comments. 50% of the profiles have up to 40 comments. A first raw characterization of comments has been obtained by some basic statistics. Table I shows, for some parameters, the maximum number of occurrences in one comment and the total number of occurrences over all comments. Minimum value of all parameters is always zero. As can be seen, comments involve a huge amount of data, and justify a more detailed analysis of their characteristics. By looking at the distribution of the previous parameters, it comes out that a large number of comments contains only text. Indeed, 89.3% of comments do not contain links, 86.3% do not contain images, and 99.2% do not contain objects. Looking at percentile values, we discover that 98% of comments have less than three external references and two images. Hence, it seems that external references are mainly concentrated in few comments. Moreover, 90% of the comments contain up to 42 words and up to 226 characters. 5.7% of the comments do not contain words. In order to characterize user behavior, comment has been analyzed on a profile basis, that is, statistics on comments have been computed for each profile as average with respect to the number of comments in the profile, hence obtaining a set of parameter values characterizing the single profile. Table II summarizes average values, standard deviation and quartiles values. Statistics for the number of objects are close to zero, and are not shown in the table. The minimum number of comments is one, while the minimum value for all other parameters is always zero. Standard deviation values denote a high variability in parameter distribution. Moreover, looking at quartile values, we note that 3rd quartile is very close to the average, which, in turn, is always larger than the median, for all parameters. This means that all parameters distributions have long tails, that is, reveals the presence of parameters having values which are very high and different from the average behavior of the distribution. This characteristic will be better analyzed in the subsequent analysis. Looking at the numbers of external references contained in a profiles, it comes out that on average, a profile contains 0.38 links in comments, 0.29 images, one exclamation and very few emoticons and objects. Moreover, 20% of user profiles, namely 290,000, have zero links in their comments. In order to derive typical user behaviors, more advanced statistical techniques, such as clustering, have to be applied. Clustering is a multidimensional statistical analysis technique used to discover groups of points having similar characteristics. Clustering algorithms [19] partition a set of points into groups, or clusters, such that points belonging to the same cluster exhibit similar behavior, that is, distance among points within a cluster is smaller than the distance among points of different groups. A cluster is represented by its centroid, that is, the geometric center of the group. From the point of view of clustering techniques, a user profile is represented as a point in a multidimensional space, the number of dimensions being the number of parameters used to characterize each profile. For the analysis of the user profiles we used the k-means clustering algorithm, in which the similarity criterion is based on the Euclidean distance. Since the objective of the study was to evaluate user characteristics related to comments, the number of comments and the number of links to Web pages and of total words contained in have been used as characterizing parameters. Other parameters have been discarded because highly correlated. Indeed, correlation indexes have been computed in order to discover dependencies. Highly correlated parameters are the number of English words, of valid words, of total words and of clean characters. The $R$ environment [20] has been used to compute correlations, to apply clustering, and to derive profile characteristics. In cluster analysis, only profiles which are relevant from the point of view of content, having an average number of external references to Web pages larger that one, have been taken into account. Hence, 119,842 users have been considered. As a result of the clustering algorithm, users profile have been subdivided into three groups. Table III summarizes centroids values and number of user profiles belonging to the three clusters. Cluster one groups 80.7% of user profiles, having on average 75.59 comments and 1.57 links. These represent the majority of users, having a high number of comments in their pages, and characterized by the smallest number of references to external links contained in. To the second cluster belong users having a high number of external references in their comment; these users correspond to the tail of the distribution of links. Then, there is a minority of users, about 7.5% of the considered profiles, belonging to group three, having a small number of comments in their pages, but have the highest number of total words. Moreover, looking at the other parameters characterizing users, it has been noticed that these users have also the highest number of clean characters and valid words. A different view of the result of cluster analysis is given by the scatter plots of Figure 2, which show the characteristics of user profiles subdivided among groups. Each point represents the projection in the two-dimensional space of a user profile, expressed by two of the parameters used for its characterization. Profiles belonging to the first, second and third cluster, are represented in figure by plus signs, circles, and triangles, respectively. Note that, in order to make figure more readable, high values are not plotted. Looking at cluster one, it can be noticed that it contains users having a high number of comments in their profiles, but “poor” in terms of number of words and links. To the second cluster, belong users having a small number of comments, but a very high number of links. Finally, third cluster groups users having few comments, which however contain a high number of words. We can conclude that the minority of users have a small number of comments in their pages, but written in a formally correct way. Moreover, when very popular users attract many comments from friends, the content is “poor” in external references. ### Analysis of external references When writing a comment, a user can insert HTML tags in order to specify external references to Web pages, images and animated objects. As already seen, only about 9% of users have at least one link inserted in comments in their page. However, it is interesting and important to see which external sites are accessed and how accesses are distributed. In the total number of comments considered, a total number of 48,317,140 references to images have been found, referring to 468,564 different sites (see Table I). Two sites, namely, www.photobucket.com and www.imageshack.us cover 50% of references. Moreover, the 18 most popular sites are responsible for 70% of the total number of references. Comments contain also 47,876,519 links to external Web sites, and 260,625 different sites are accessed. Moreover, the first two most common sites, namely, www.msplinks.com and Table IV shows the most popular sites used for referencing images and Web pages. <table> <thead> <tr> <th>Sites</th> <th>Percentage</th> </tr> </thead> <tbody> <tr> <td><a href="http://www.photobucket.com">www.photobucket.com</a></td> <td>43.1%</td> </tr> <tr> <td><a href="http://www.imageshack.us">www.imageshack.us</a></td> <td>7.3%</td> </tr> <tr> <td>fc.fdots.com</td> <td>4.0%</td> </tr> <tr> <td>myspacecdn.com</td> <td>2.7%</td> </tr> <tr> <td><a href="http://www.glitter-graphics.com">www.glitter-graphics.com</a></td> <td>2.2%</td> </tr> <tr> <td>Web pages</td> <td></td> </tr> <tr> <td><a href="http://www.msplinks.com">www.msplinks.com</a></td> <td>53.2%</td> </tr> <tr> <td><a href="http://www.photobucket.com">www.photobucket.com</a></td> <td>6.5%</td> </tr> <tr> <td>profile.myspace.com</td> <td>3.2%</td> </tr> <tr> <td><a href="http://www.myspace.com">www.myspace.com</a></td> <td>3.2%</td> </tr> <tr> <td><a href="http://www.imageshack.us">www.imageshack.us</a></td> <td>1.3%</td> </tr> </tbody> </table> Another type of reference as also been discovered. Indeed, links and images, which are inserted as plain text, still remain after removing HTML tags. These references are simply read by users and cannot be accessed, but reflect a sort of communication which cannot be ignored. The number of this type of references is not negligible. 665,879 different links have been recognized in comments, giving a total amount of 13,642,564 occurrences. B. Analysis of the words On average, a comment contains 248.5 characters, but, after removing special characters, HTML tags, and punctuation, just 132 characters remain: this “overhead” of 53% is due so the inclusion of content other than words, such as, references to external document, and to special punctuation. Each comment contains on average 26.1 words, and 90.2% of them belong to one of the selected languages, that is, are considered “valid”. Within these, English words account for 97.18%, and are on average 23 per comment. Words belonging to at least one dictionary have been classified as valid, whereas non-valid words could be due typo, as well as belong to the “Internet language”, namely slang dictionary and emoticons. Table V summarizes overall characteristics of comments in terms of number of unique valid and non-valid words, total number of occurrences, and average per comment. Among valid words, “rare” and “common” words can be easily identified, according to their frequency. About 101,000 words, namely 23% of the words, can be classified as “rare”, appearing just once. Moreover, “common” words, that is, very frequently used, are very few; 1699 very used words, are only 0.38% of unique words, but cover 90% of occurrences. Figure 3 shows frequency of most used words; the most popular word appears about 300 million times. Non-valid words are "expressions" in an informal slang language, and are distributed in a clearly different way with respect to valid ones. Non-valid "rare" words, which appear just once, are many more than valid "rare" words, accounting for 69.3% of non-valid words. Moreover, 89.7% words appear less than 7 times. The 166 most frequent words account for 30% of total occurrences, and the 1002 most frequent for 50%. From these data, a model of user comes out using a poor, absolutely not variegated recognized language. Moreover, the number of unrecognized words is impressively high: in 41% of comments more than 10% of the words contained in the comment are non-valid. A few words have been recognized as belonging to more than one of the selected language. Table VI summarizes outcomes. <table> <thead> <tr> <th>language</th> <th>unique words</th> <th>total</th> </tr> </thead> <tbody> <tr> <td>unique</td> <td>378,637</td> <td>2,962,720,000</td> </tr> <tr> <td>English</td> <td>100,404</td> <td>2,800,680,000</td> </tr> <tr> <td>French</td> <td>42,413</td> <td>30,627,358</td> </tr> <tr> <td>Spanish</td> <td>53,227</td> <td>18,714,384</td> </tr> <tr> <td>German</td> <td>45,619</td> <td>45,725,760</td> </tr> <tr> <td>Italian</td> <td>79,360</td> <td>10,308,068</td> </tr> <tr> <td>Portuguese</td> <td>18,933</td> <td>7,964,743</td> </tr> <tr> <td>Dutch</td> <td>38,681</td> <td>48,699,522</td> </tr> <tr> <td>2 languages</td> <td>47,078</td> <td>1,859,274,277</td> </tr> <tr> <td>3 languages</td> <td>11,384</td> <td>797,205,923</td> </tr> <tr> <td>4 dictionary</td> <td>2,965</td> <td>406,560,549</td> </tr> </tbody> </table> TABLE VI COMPOSITION OF COMMENTS IN TERMS OF LANGUAGES USED. English is clearly the most used language; 121,228 words have been classified as English, accounting for a total of about 7 billion words, that is, 96.99% of the total number of words. Moreover, it has also been noticed that the first 36 most popular words are English and account for about 2.65 billion of total occurrences, and that the number of English words in a profile is highly correlated with the number of words and of "clean" characters. IV. Conclusions This paper presents an analysis of MySpace comment structure. A huge amount of user profiles have been analyzed in order to extract and characterize the content posted in user comments. A comment has been described by means of parameters concerning its length, the language used, and the content inserted through external references. Basic statistics are derived, and typical user behaviors have been identified, depending on the number of comments and on comments composition. This can be very helpful for social network analysis systems that apply either statistical or semantic analysis techniques to the comments they extract with keyword search. Future research could include comparison with other popular social network sites, such as, Facebook, and the analysis of profile evolution over time. Further analysis on the external links managed through msplinks is also required. Moreover, the analysis on the external sites accessed through comments could be extended to a deeper analysis of the different objects referenced, helping in discovering the most referenced multimedia content. REFERENCES
Disclaimer This presentation outlines our general product direction and should not be relied on in making a purchase decision. This presentation is not subject to your license agreement or any other agreement with SAP. SAP has no obligation to pursue any course of business outlined in this presentation or to develop or release any functionality mentioned in this presentation. This presentation and SAP's strategy and possible future developments are subject to change and may be changed by SAP at any time for any reason without notice. This document is provided without a warranty of any kind, either express or implied, including but not limited to, the implied warranties of merchantability, fitness for a particular purpose, or non-infringement. SAP assumes no responsibility for errors or omissions in this document, except if such damages were caused by SAP intentionally or grossly negligent. Abstract Software security remains a critical topic of interest to all companies and to the information technology industry. The security of a specific system thereby also significantly depends on the secure configuration of this system. With Configuration Validation within SAP Solution Manager, SAP offers a tool to validate various kinds of software configuration items. This helps to standardize and harmonize configuration items within the ABAP and Java world cross system, using a single configuration item repository within SAP Solution Manager. In this hands-on session participants learn to use configuration validation templates with typical use cases in the space of Security Validation. The basic set-up of Configuration Validation is explained step by step and described for typical reporting scenarios. As the use case, a typical software level and parameter validation scenario will be implemented. We’ll use the latest options of SAP Solution Manager 7.1 to define a target system which exactly matches the strong requirements of many corporate security policies. Agenda - **Best Practices-based Services** **Security Tools and Services** - EarlyWatch Alert (EWA) – Security Chapter - Security Notes Report (RSECNOTE) - System Recommendations - Security Optimization Service (SOS) - Configuration Validation - Run SAP Standard for Security Appendix - SAP Enterprise Support Report Establishing Security in a Structured Approach ANALYZE – the vulnerable points of the SAP solution in order to - Decrease the risk of a system intrusion - Ensure the confidentiality of business data - Ensure the authenticity of users - Substantially reduce the risk of costly downtime due to wrong user interaction CHECK – and implement Application Lifecycle Security - Security Patch Management / System Recommendation - Security Configuration Monitoring e.g. EarlyWatch Alert, Security Optimization Service and Configuration Validation SAFEGUARD – implementation of security functionality - Secure configuration e.g. SAP Gateway Security and SAP Message Server Security - SAP BusinessObjects Governance, Risk, and Compliance Solutions - SAP NetWeaver Identity Management Security Management – Continuous Process Along a Quality Circle - Establish the objectives and processes necessary to deliver results in accordance with the expected output. - Implement the new processes and procedures. - Analyze the differences and determine their root cause. Determine where to apply changes that will lead to improvements and the expected results. - Measure the new processes and compare the results via indicators (KPIs) against the expected results in order to identify possible differences. The security plans (Plan) are implemented (Do) and the implementation is then evaluated (Check). After the evaluation both plans and implementation of the plan are carried out (Act). IT Security Lifecycle Based on the SAP Solution Manager - Configuration Validation - + EGI Empowerment - GRC Solutions - + Safeguarding - SAP NW IdM - + Safeguarding - Single Sign On Solutions - + Safeguarding - SOS EoD Services - SOS Remote Service - SOS Onsite Service For each IT organization - Value Proposition - RunSAP Security Standard - Security Workshop - Security On-boarding - Security in EWA - Security in TSM - Security in ESR - SOS Self Service - + EGI Empowerment Security Notes Recommendations - Security Notes Tool RSECNOTE - System Recommendations EGI Expert Guided Implementation ESR Enterprise Support Report EWA EarlyWatch Alert SOS Security Optimization Service SSO Single Sign-On GRC Governance, Risk & Compliance Agenda ➡️ **Best Practices-based Services** **Security Tools and Services** ➡️ *EarlyWatch Alert (EWA) – Security Chapter* ➡️ *Security Notes Report (RSECNOTE)* ➡️ *System Recommendations* ➡️ *Security Optimization Service (SOS)* ➡️ *Configuration Validation* ➡️ **Run SAP Standard for Security** **Appendix** ➡️ *SAP Enterprise Support Report* The Role of EarlyWatch Alert (EWA) for Security SAP EarlyWatch Alert (EWA) (see http://service.sap.com/ewa) SAP EarlyWatch Alert is an important part of making sure that your core business processes work. It is a tool that monitors the essential administrative areas of SAP components and keeps you up to date on their performance and stability. SAP EarlyWatch Alert runs automatically to keep you informed, so you can react to issues proactively, before they become critical. Security in the EarlyWatch Alert: - The EWA Report includes selected information on critical security observations - SAP Security Notes: ABAP and Kernel Software Corrections - Default Passwords of Standard Users - Password Policy - Gateway and Message Server Security - Users with Critical Authorizations - More detailed and additional information can be found with the help of the security self-services EarlyWatch Alert in the “SAP Engagement and Service Delivery” Work Center Filter sessions by your solution System name is shown in column “Context” Alerts are visible on tab “Details” Access Word report on tab “Attachments” EarlyWatch Alert in the “System Monitoring” Work Center Filter sessions by your solution Generate HTML report During this EarlyWatch Alert Session, we detected issues that could potentially affect your system. We recommend that you take corrective action as soon as possible. **Alert Overview** - [-] Standard users including SAP or DDI have default passwords. - [-] Security-related SAP HotNews have not been applied in the system. - [-] Security weaknesses identified in the Gateway or the Message Server configuration **Check Overview** <table> <thead> <tr> <th>Topic Rating</th> <th>Topic</th> <th>Subtopic Rating</th> <th>Subtopic</th> </tr> </thead> <tbody> <tr> <td>[ ]</td> <td>Security</td> <td>[ ]</td> <td>SAP Security Notes: AGAP and Kernel Software Corrections</td> </tr> <tr> <td>[ ]</td> <td></td> <td>[ ]</td> <td>Default Passwords of Standard Users</td> </tr> <tr> <td>[ ]</td> <td></td> <td>[ ]</td> <td>Password Policy</td> </tr> <tr> <td>[ ]</td> <td></td> <td>[ ]</td> <td>Gateway and Message Server Security</td> </tr> <tr> <td>[ ]</td> <td></td> <td>[ ]</td> <td>Users with Critical Authorizations</td> </tr> </tbody> </table> EarlyWatch Alert Chapter “Security” Overview 7 Security Critical security issues were found in your system. See the information in the following sections. <table> <thead> <tr> <th>Rating</th> <th>Check</th> </tr> </thead> <tbody> <tr> <td>🔴</td> <td>Security-related SAP Notes</td> </tr> <tr> <td>🔴</td> <td>Default Passwords of Standard Users</td> </tr> <tr> <td>✔</td> <td>Password Policy</td> </tr> <tr> <td>🚫</td> <td>Gateway and Message Server Security</td> </tr> <tr> <td>🚫</td> <td>Users with Critical Authorizations</td> </tr> </tbody> </table> 7.1 SAP Security Notes: ABAP and Kernel Software Corrections Software corrections from SAP Security HotNews have been identified as missing on this system. Most probably, your system is exposed to corresponding security threats. **Recommendation:** Apply SAP Security Notes, which are relevant to your system! The tool RSECNTE in transaction ST13 provides you with a list of those SAP Security Notes that have been identified as missing in this EWA check. RSECNTE covers SAP's Security HotNews with software-related corrections for ABAP or Kernel and an additional selection of SAP Security Notes. For more information, refer to SAP Note [888889](https://service.sap.com/securitynotes). In the Security Notes list on the SAP Service Marketplace referenced above, the flag “Automatic check in EWA” (last column) identifies those SAP Security Notes, for which the implementation is completely checked in the EWA. In tool RSECNTE, 7 SAP Security Notes have manually been marked as not to be considered. 7.2 Default Passwords of Standard Users Standard users including SAP® or DDIC have default passwords. **Recommendation:** Use report **RSUSR003** to check the usage of default passwords by standard users. Ensure that - user SAP® exists in all clients - users SAP®, DDIC, SAPCPIC and EARLYWATCH have non-default passwords in all clients - profile parameter login/no_automatic_user_sapstar is set to 1. For more information, see section "Protecting Standard Users" and section "Profile Parameters for Logon and Password (Login Parameters)" either in the SAP Help Portal or in the SAP NetWeaver AS ABAP Security Guide. Make sure that the standard password for user TMSADM is changed in client 000 and delete this user in any other client. The SAP note **1414256** describes a support tool for changing the password of user TMSADM in all systems of the transport domain. 7.3.1 Password Complexity PARAMETER: LOGIN/MIN_PASSWORD_LNG <table> <thead> <tr> <th>Rating</th> <th>Instance</th> <th>Current Value</th> <th>Recommended Value</th> </tr> </thead> <tbody> <tr> <td>F</td> <td>All instances</td> <td>3</td> <td>8</td> </tr> </tbody> </table> The current system settings allow a minimum password length less than 6 characters. This allows weak passwords. Attackers may successfully recover such passwords and exploit this to gain unauthorized access to the system. **Recommendation:** Use a minimum value of 8 for the profile parameter `login/min_password_lng`. In addition, SAP provides options to enforce complex passwords. Find the current settings of the corresponding profile parameters in the following table. <table> <thead> <tr> <th>Parameter</th> <th>Instance</th> <th>Current Value</th> </tr> </thead> <tbody> <tr> <td>login/min_password_letters</td> <td>All instances</td> <td>0</td> </tr> <tr> <td>login/min_password_uppercase</td> <td>All instances</td> <td>0</td> </tr> <tr> <td>login/min_password_lowercase</td> <td>Instance dependent</td> <td>3; 5; 0</td> </tr> <tr> <td>login/min_password_digits</td> <td>All instances</td> <td>2</td> </tr> <tr> <td>login/min_password_specials</td> <td>Instance dependent</td> <td>1; 3; 5</td> </tr> </tbody> </table> 7.3.2 Validity of Initial Passwords **PARAMETER:** login/password_max_idle_initial <table> <thead> <tr> <th>Rating</th> <th>Parameter</th> <th>Instance</th> <th>Current Value</th> </tr> </thead> <tbody> <tr> <td>🚫</td> <td>login/password_max_idle_initial</td> <td>All instances</td> <td>0</td> </tr> </tbody> </table> Initial passwords are valid for an unrestricted time. **Recommendation:** Restrict the password validity to 14 days or less. More information can be found in SAP Note [862989](https://support.sap.com) and in section "Profile Parameters for Logon and Password (Login Parameters)" either in the SAP Help Portal or in the SAP NetWeaver AS ABAP Security Guide. 7.4 Gateway and Message Server Security 7.4.1 Kernel Patch Level <table> <thead> <tr> <th>Rating</th> <th>Kernel Release</th> <th>Current Kernel Patch Level</th> <th>Minimal Required Kernel Patch Level</th> </tr> </thead> <tbody> <tr> <td>1</td> <td>701</td> <td>89</td> <td>98</td> </tr> </tbody> </table> To enable certain Gateway and Message Server security functionality, a minimum patch level of the kernel is required. Your system currently misses this requirement. **Recommendation:** Update the kernel of your system to the newest kernel patch level available. At least update to a kernel patch level equal or higher than the minimal required kernel patch level given above. Additional information can be found in SAP Note 1298433. 7.4.2 Gateway Security Gateway Security Properties The parameter gw/reg_no_conn_info controls the activation of certain security properties of the SAP Gateway. It is defined as a bit mask with one bit per property. On your system the following properties were identified: <table> <thead> <tr> <th>Rating</th> <th>Value Name</th> <th>Current Value</th> <th>Recommended Value</th> </tr> </thead> <tbody> <tr> <td></td> <td>Bypassing security in reg_info &amp; sec_info</td> <td>0</td> <td>1</td> </tr> <tr> <td>✔️</td> <td>Bypassing sec_info without reg_info</td> <td>2</td> <td>2</td> </tr> <tr> <td></td> <td>CANCEL registered programs</td> <td>0</td> <td>4</td> </tr> <tr> <td></td> <td>Uppercase/lowercase in the files reg_info and sec_info</td> <td>0</td> <td>8</td> </tr> </tbody> </table> **Recommendation:** Enable the missing properties by adding the respective recommended values to the current value of gw/reg_no_conn_info. More information regarding gw/reg_no_conn_info can be found in SAP Note [1444282](http://support.sap.com/1444282). Enabling an Initial Security Environment **PARAMETER: gw/acl_mode** <table> <thead> <tr> <th>Rating</th> <th>Current Value</th> <th>Recommended Value</th> </tr> </thead> <tbody> <tr> <td>★</td> <td>0</td> <td>1</td> </tr> </tbody> </table> **Recommendation:** Parameter gw/acl_mode can be set to 1 to activate a more secure default behavior in case that either of the access control lists defined by gw/sec_info and gw/reg_info does not exist. SAP recommends to set gw/acl_mode=1 to establish an additional line of defense in case any of the mentioned access control lists is missing. More information can be found in SAP Note 1480644. Gateway Access Control Lists **PARAMETERS: gw/sec_info gw/reg_info** <table> <thead> <tr> <th>Rating</th> <th>Instance</th> <th>Error Condition</th> </tr> </thead> <tbody> <tr> <td>★</td> <td>All instances</td> <td>gw/sec_info is not defined or empty</td> </tr> </tbody> </table> **Recommendation:** The profile parameters gw/sec_info and gw/reg_info provide the file names of the corresponding access control lists. These access control lists are critical to control the RFC access to your system including connections to RFC servers. You should create and maintain both access control lists, which can be done via transaction SMGW. More information can be found in SAP Note 1425765. 7.4.3 Message Server Security Separation of Internal and External Message Server Communication <table> <thead> <tr> <th>Parameters: rdisp/msserv rdisp/msserv_internal</th> </tr> </thead> <tbody> <tr> <td>Rating</td> </tr> <tr> <td>--------</td> </tr> <tr> <td>![ ]</td> </tr> <tr> <td>![ ]</td> </tr> </tbody> </table> **Recommendation:** Communication with the message server should be separated into SAP system internal communication (TCP/IP port defined by rdisp/msserv_internal) and communication e.g. from user SAPGUIs to the system (TCP/IP port defined by rdisp/msserv). Network firewalls should block access to the port given in rdisp/msserv_internal from outside the SAP system. Set parameter rdisp/msserv_internal to a TCP/IP port number different to the port number given in rdisp/msserv and additionally protect access to the internal message server port by appropriate firewalls. More information can be found in SAP Note 821875. Message Server Administration Allowed for External Clients **PARAMETER: MS/MONITOR MS/ADMIN_PORT** <table> <thead> <tr> <th>Rating</th> <th>Parameter</th> <th>Current Value</th> <th>Recommended Value</th> </tr> </thead> <tbody> <tr> <td>![High Risk Icon]</td> <td>ms/monitor</td> <td>1</td> <td>0</td> </tr> <tr> <td>![High Risk Icon]</td> <td>ms/admin_port</td> <td>12345</td> <td>0</td> </tr> </tbody> </table> **Recommendation:** SAP recommends to block external administration of the message server by setting the profile parameters ms/monitor and ms/admin_port both to the value 0. More information can be found in SAP Note 821875. The profile parameter ms/admin_port can be set dynamically via transaction SMMS -> Goto -> Security Settings. Message Server Access Control List **PARAMETER: MS/ACL_INFO** <table> <thead> <tr> <th>Rating</th> <th>Error Condition</th> </tr> </thead> <tbody> <tr> <td>![High Risk Icon]</td> <td>ms/ACL_INFO is not defined or empty</td> </tr> </tbody> </table> **Recommendation:** The profile parameter ms/ACL_INFO provides the file name of the message server’s access control list. This list controls, which application servers are allowed to log on to the message server. SAP recommends to define and properly maintain this list to prohibit rogue application servers to join the system. More information can be found in SAP Note 821875. 7.5 Users with Critical Authorizations For more information about the following check results, please refer to SAP Note [863362]. [...] 7.5.1 Users Authorized to Display all Tables Unauthorized access to sensitive data is possible if too many users are granted this authorization. The number of users with this authorization is stated for each client. <table> <thead> <tr> <th>Client</th> <th>No. of Users Having This Authorization</th> <th>No. of Valid Users</th> <th>Rating</th> </tr> </thead> <tbody> <tr> <td>600</td> <td>222</td> <td>249</td> <td></td> </tr> <tr> <td>800</td> <td>4110</td> <td>4292</td> <td></td> </tr> </tbody> </table> **Authorization objects:** Object 1: S_TCODE with TCD=SE16, TCD=SE16N, TCD=SE17, TCD=SM30, or TCD=SM31 Object 2: S_TABU_DIS with ACTVT = 03 or 02 and DICBERCLS = * 7.5.2 Users Authorized to start all Reports 7.5.3 Users Authorized to Debug / Replace 7.5.4 Users Authorized to Display Other Users Spool Request Exercises EarlyWatch Alert report Agenda - Best Practices-based Services Security Tools and Services - EarlyWatch Alert (EWA) – Security Chapter - Security Notes Report (RSECNOTE) - System Recommendations - Security Optimization Service (SOS) - Configuration Validation Run SAP Standard for Security Appendix - SAP Enterprise Support Report Value Proposition The SAP Security Optimization Service is designed to verify and improve the security of the SAP systems of customers by identifying potential security issues and giving recommendations on how to improve the security of the system. Keeping the security and availability of customer SAP solutions high is a tremendous value to customers’ businesses - a value delivered by the SAP Security Optimization Service. Analysis is the key to this value, which is necessary to: - Decrease the risk of a system intrusion - Ensure the confidentiality of business data - Ensure the authenticity of users - Substantially reduce the risk of costly downtime due to wrong user interaction More information can be found under the alias SOS in the SAP Service Marketplace: http://www.service.sap.com/sos SAP Security Optimization Service – Overview - The SAP Solution Manager offers the possibility to locally execute the SAP Security Optimization Service - All completely automated checks in ABAP systems - No additional costs for this service SAP Security Optimization - Broad range of security checks extending the Self-Service checks - Performed by experienced service engineers - Part of CQC service offering SAP Security Optimization Remote Service - Individual range of security checks, e.g. for the SAP Enterprise Portal - Performed by specialists - Additional costs for this service SAP Security Optimization Onsite Service Security Optimization Service Scope of Remote Service and Self Service **SAP NetWeaver Application Server ABAP** - Basis administration check - User management check - Super users check - Password check - Spool and printer authorization check - Background authorization check - Batch input authorization check - Transport control authorization check - Role management authorization check - Profile parameter check - SAP GUI Single Sign-On (SSO) check - Certificate Single Sign-On (SSO) check - External authentication check **SAP NetWeaver Application Server Java** - Landscape check - Configuration check - SSL check - Administration check **SAProuter** - SAProuttab check - OS access check - SNC check **SAP Enterprise Portal** - Landscape check - Configuration check - Administration check - SSL check - Authorization check for portal content, user management and administration Scope of the SOS Self Service Scope of the Security Optimization Self Service for the SAP NetWeaver Application Server ABAP - Basis administration check - User management check - Super users check - Password check - Spool and printer authorization check - Background authorization check - Batch input authorization check - Transport control authorization check - Role management authorization check - Profile parameter check - SAP GUI Single Sign-On (SSO) check - Certificate Single Sign-On (SSO) check - External authentication check In order to determine the actual risk, the vulnerabilities are ranked using a rating logic. The rating is based on the severity and probability of each vulnerability. A report is created containing the identified vulnerabilities of the analyzed SAP system. The report contains recommendations to eliminate or reduce the vulnerabilities found during the Security Optimization Service. The implementation of the recommended security measures can be done: - By the customer - By SAP security consulting - By certified SAP partners Managed System Solution Manager Questionnaire The questionnaire is filled out by the customer to prepare the service. The questionnaire contains about 25 questions. Specification of known users with critical authorizations in the questionnaire skips them from the report. This helps to keep the report readable and to do a correct risk analysis. Customize the look of the report. Selection of the tested clients. 2.1 Print the User Data (All Checks) Procedure If you want user data (first name, last name and department of the user) printed in the User Data*. If you do not select, the field only the user name is printed. When creating the ST14 data the sending of the user data to SAP(first and last name) parameter. Print User Data? Flag Activate if user data wanted 2.2 Download and Check for Very Weak Passwords (0145) Procedure If you want your user passwords checked, select the field "Download Encrypted Passwords". In this case we download the encrypted passwords of your users and try a very simple dictionary attack on them. Download passwords? Flag Activate if pwd check wanted 2.3 User for Remote Access from SAP (0531) Procedure Enter the name of the user (or one of the users) that you hand over to SAP for logging on to your SAP system. Client User ID 2.4 User Segregation (0004) Procedure If you have segregated your users in different user groups, select the field "User Segregation" in the table. Segregation in Usergroups Flag Activate checkbox if used 2.5 Super Users (0021) Procedure List for each client the known super users. These are the users having the profile SAP_ALL. - Please mention the users with user type "dialog", "service", "system" or "communication". - If a super user exists in all clients, you can also insert "ALL" in the field "Client" instead of listing all clients. Client User © 2012 SAP AG. All rights reserved. ### Customer Report: Action Items The action items list on top of the report gives a good overview about the complete system status. The action items are created automatically of all checks rated with high risk. The list can be individually adapted. We use the red traffic light as “high risk” and the yellow traffic light as “medium risk.” “Green” results are normally skipped in order to reduce the size of the report. All checks have a four-digit identifier which allows to find the detailed description in the report easily. <table> <thead> <tr> <th>Issue Description</th> <th>Action Items</th> </tr> </thead> <tbody> <tr> <td>Security Optimization, Sample Customer</td> <td><strong>3 Detected Issues</strong></td> </tr> <tr> <td><strong>Action Items</strong></td> <td></td> </tr> <tr> <td>1 Users - Other Than the System Administrators - Are Authorized to Call ST14 7. (0168)</td> <td></td> </tr> <tr> <td>6 Users - Other Than the System Administrators - Are Authorized to Maintain Users (0002)</td> <td></td> </tr> <tr> <td>1 Users - Other Than System Administrators - Are Authorized to Maintain System Profiles (0152)</td> <td></td> </tr> <tr> <td>6 Users Are Authorized to Execute All Function Modules</td> <td></td> </tr> <tr> <td>8 Users Are Authorized to Access Tables with User Data (0013)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Maintain Authorizations Directly in the Production System (0074)</td> <td></td> </tr> <tr> <td>1 Unexpected Users Are Authorized to Change a Super User Accounts (0026)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Delete an Authorization Check Before Transaction Start (0111)</td> <td></td> </tr> <tr> <td>5 Users Are Authorized to Delete a Client (0306)</td> <td></td> </tr> <tr> <td>7 Users Are Authorized to Create New Clients (0305)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Maintain Authorizations Directly in the Production System (0074)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Maintain Authorization Group of Tables (0515)</td> <td></td> </tr> <tr> <td>6 Users Are Authorized to Start/Stop Application Servers (0154)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Maintain System Profiles (0152)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Maintain Trusted Systems (0240)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Maintain Trusting Systems (0268)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for User Maintenance (0511)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Role Maintenance (0512)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Authorization Maintenance (0513)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Role Maintenance (0512)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Authorization Maintenance (0513)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Role Maintenance (0512)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Authorization Maintenance (0513)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Role Maintenance (0512)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Authorization Maintenance (0513)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Role Maintenance (0512)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Authorization Maintenance (0513)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Role Maintenance (0512)</td> <td></td> </tr> <tr> <td>1 Users Are Authorized to Call Function Modules for Authorization Maintenance (0513)</td> <td></td> </tr> </tbody> </table> Customer Report: Example of an Authorization Check Information in the checks: Explanation of the vulnerability Some “Unexpected” users having this authorization The number of unexpected users A recommendation how to handle this situation All checked authorization objects 6.3.7 Users - Other Than the Spool Administrators - Are Authorized to Print on all Devices (0197) Output of sensitive data can be sent accidentally to a wrong printer and could be accessed by an unauthorized employee. <table> <thead> <tr> <th>Client</th> <th>User</th> <th>Type</th> <th>Last Name</th> <th>First Name</th> <th>Department</th> </tr> </thead> <tbody> <tr> <td>300</td> <td>AARONF</td> <td>A</td> <td>Aaron</td> <td>Frank</td> <td></td> </tr> <tr> <td>300</td> <td>ANTONOV</td> <td>A</td> <td>Antonov</td> <td>Igor</td> <td></td> </tr> <tr> <td>300</td> <td>AUTUMW</td> <td>A</td> <td>Autumn</td> <td>Wallis</td> <td></td> </tr> <tr> <td>300</td> <td>BARCANI</td> <td>A</td> <td>Barcan</td> <td>Ivory</td> <td></td> </tr> <tr> <td>300</td> <td>BLACKBEARDC</td> <td>A</td> <td>Blackbeard</td> <td>Christ</td> <td></td> </tr> <tr> <td>300</td> <td>BLUEBERRYA</td> <td>A</td> <td>Blueberry</td> <td>Agneta</td> <td></td> </tr> <tr> <td>300</td> <td>BLUMBERGH</td> <td>A</td> <td>Blumberg</td> <td>Harald</td> <td></td> </tr> <tr> <td>300</td> <td>BRAUERM</td> <td>A</td> <td>Brauer</td> <td>Michael</td> <td></td> </tr> <tr> <td>300</td> <td>BUSHH</td> <td>A</td> <td>Bush</td> <td></td> <td>OFFICE</td> </tr> <tr> <td>300</td> <td>FERRYG</td> <td>A</td> <td>Ferry</td> <td>Greg</td> <td></td> </tr> <tr> <td>300</td> <td>HENSGNERJ</td> <td>A</td> <td>Hensgner</td> <td>Joan</td> <td></td> </tr> <tr> <td>300</td> <td>KINGD</td> <td>A</td> <td>King</td> <td>David</td> <td></td> </tr> <tr> <td>300</td> <td>KINGF</td> <td>A</td> <td>King</td> <td>Frank</td> <td></td> </tr> <tr> <td>300</td> <td>LANDISG</td> <td>A</td> <td>Landis</td> <td>George</td> <td></td> </tr> <tr> <td>300</td> <td>ROBERTA</td> <td>A</td> <td>Robert</td> <td>Alexander</td> <td></td> </tr> <tr> <td>300</td> <td>VOLKOVIC</td> <td>A</td> <td>Volkov</td> <td>Chris</td> <td></td> </tr> <tr> <td>300</td> <td>WINTERH</td> <td>A</td> <td>Winter</td> <td>Natascha</td> <td></td> </tr> <tr> <td>300</td> <td>XERTAMY</td> <td>A</td> <td>Xertam</td> <td>Yanis</td> <td></td> </tr> </tbody> </table> Count: 220 Evaluated result: More than 20% of your users, of at least one client, can print on all devices. Recommendation: Use the Profile Generator (PFCG) to correct roles. Use the transactions SU02 (Maintain Profiles) and SU03 (Maintain Authorizations) to correct profiles and authorizations, depending on your environment. You can use the authorization info system (SUIM) to check the results. For this check examine the roles or profiles that include the authorization objects listed below. Authorization object: Object: S_SPO_DEV with SPODEVICE = *. Sample Questionnaire and Report How to Identify „Top Issues“ Candidate „Missing Security Notes“ Candidate: „**Missing Security Notes**“ Threat: Missing security Notes – especially missing Security HotNews – point to security weaknesses which are identified as present in your system. These weaknesses may have the potential to be exploited by anyone to anonymously execute code, access data or change your system bypassing system settings and authorization checks. In the SOS report look for section „**Basis Authorization“ – „Basis Administration“ – „Security-related SAP Notes““ Action: Identify, which Security Notes are missing and implement them on the system How to Identify „Top Issues“ Candidate „Standard Users with Default Password“ - Candidate: „Standard Users with Default Password“ - Threat: Standard users with default passwords allow anyone, who is able to establish a network connection to your system, to anonymously enter it and execute code under potentially high authorizations. - In the SOS report look for section „User Authorization“ – „Standard Users“ Check-ID 0041 - Action: Change the password - Remark: Look for the other checks in this SOS section as well. They also contain valuable recommendations to protect your system from this threat! How to Identify „Top Issues“ Candidate „Insufficient Password Policy“ Candidate: „Insufficient Password Policy“ Threat: Weak passwords may give unauthorized people access to potentially powerful accounts. This risks the confidentiality, integrity and availability of your data. In the SOS report look for section „Authentication“ – „Passwords“ Check-ID 0123 Action: Carefully review the whole „Password“ section of the SOS. Decide on an appropriate password policy (if not already defined) and implement it with recommended settings as given suggested in the SOS report. 4 Special Focus Checks 4.1 Additional Super User Accounts Found (0022) In this system, the following super user accounts were found that were not mentioned in the questionnaire. (These are the users having the profile SAP_ALL). All superuser accounts that were found in your system are REMOVED from all the following checks. This means that checks that report 5 authorized users, for example, actually have 5 users and ALL superuser accounts authorized for your system. Keep this in mind when you look at all other checks below. <table> <thead> <tr> <th>Client</th> <th>User</th> <th>Type</th> <th>Last Name</th> <th>First Name</th> <th>Department</th> <th>User Group</th> </tr> </thead> <tbody> <tr> <td>000</td> <td>BASIS01</td> <td>A</td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>000</td> <td>BASIS02</td> <td>A</td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>000</td> <td>BASIS03</td> <td>A</td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>000</td> <td>COURT</td> <td>A</td> <td></td> <td></td> <td></td> <td></td> </tr> </tbody> </table> - Candidate: „Users with SAP_ALL“ - Threat: Users with „SAP_ALL“ can completely compromise your system – intentionally or unintentionally. Moreover they can not only circumvent any authorization checks but any auditing as well. - In the SOS report look for section „Special Focus Checks“ – „Additional Super User Accounts Found“ - Check-ID 0022 - Action: Avoid „SAP_ALL“ as far as possible and try to restrict it to relevant emergency accounts which are only used in emergency situations under tight control. Add accepted SAP_ALL accounts to the questionnaire and closely monitor this section in future SOS runs. How to Identify „Top Issues“ Candidate „Users with full authorization for S_RFC“ - Candidate: „Users with full authorizations for S_RFC“ - Threat: These users can be used to call any RFC function from outside the system. - In the SOS report look for section „Basis Authorization“ – „Incoming RFC“ Check-ID 0241 - Action: Limit users with authorization S_RFC with RFC_NAME=* to the minimum. Limit the RFC functions, for which a specific user is authorized to the required set – or remove the authorization completely where possible. How to Identify „Top Issues“ Candidate „Users authorized to debug / replace“ - **Candidate:** „**Users authorized to debug / replace**“ - **Threat:** These users can run all programs with debug / replace, e.g. replace an data value or bypass any authorization check. - **In the SOS report look for section „**Change Management“ – „**Change Control“** Check-ID 0308 - **Action:** Limit users with this authorization to the unavoidable minimum. Authorization for „Debug / Replace“ should not be present at all in production systems. How to Identify „Top Issues“ Candidate „Users authorized to start all reports“ Candidate: „Users authorized to start all reports“ Threat: These users can start all reports, potentially also bypassing certain S_TCODE checks. In the SOS report look for section „Change Management“ – „Data & Program Access“ Check-ID 0512 Action: Limit users with this authorization to the unavoidable minimum How to Identify „Top Issues“ Candidate „Users authorized to display all tables“ - Candidate: „Users authorized to display all tables“ - Threat: These users can view all tables, including technical information as well as any business or personal data - In the SOS report look for section „Change Management“ – „Data & Program Access“ Check-ID 0513 - Action: Limit users with this authorization to the unavoidable minimum How to Identify „Top Issues“ Candidate „Users authorized to execute all function modules“ - **Candidate**: „Users authorized to execute all function modules“ - **Threat**: These users can execute any function modules, where several critical function modules do not contain any further authorization checks. - **In the SOS report look for section „Change Management“ – „Data & Program Access“ Check-ID 0520** - **Action**: Limit users with this authorization to the unavoidable minimum How to Identify „Top Issues“ Candidate „Users with extensive authorizations“ - Candidate: „Users with extensive authorizations“ - Threat: These users have so many authorizations that they are close to a super user. - In the SOS report look for section „User Authorization“ – „Super Users“ Check-ID 0023 Beyond this have an additional general look over the SOS authorization checks whether there users that are listed unexpectedly often or in unexpected places. Especially look in SOS checks with „Evaluated Risk – High“ - Action: Limit the authorization for these users to the required minimum Candidate: "RFC destinations with login information" Threat: These RFC destinations allow access to remote systems with stored login information. Unauthorized usage will compromise the security of the remote system. In the SOS report look for section "Basis Authorization" – "Outgoing RFC" Check-ID 0254 Action: For each RFC connection with login information find a responsible persons, who knows about the need and purpose for this entry. Check the other entries whether they can be removed and remove all entries, that are not needed any longer. How to Identify „Top Issues“ Candidate „Security Audit Log Deactivated“ - **Candidate: „Security Audit Log Deactivated“** - **Threat:** If the Security Audit Log is deactivated, security critical events are not recorded and are neither available for monitoring nor for the follow-up of any security incident. - **In the SOS report look for section „Authentication“ – „General Authentication“** **Check-ID 0136** - **Action:** Switch on the Security Audit Log in all clients. The Security Audit Log is optimized for performance. So if logging is restricted to critical security violations only, activation of the Security Audit log should be possible on all systems including production systems. Deriving an Action Plan Deriving an Action Plan is easy ... in theory. The SOS report is designed to already contain everything you need for it: - a general introduction - the findings and explanations - risk ratings - recommendations - technical background information So just go ahead! Deriving an Action Plan ... is not that easy when the report is huge When the SOS report is huge - working on it as described on the slide before takes a lot of time and resources - ... and may even cause that nothing happens at all. The goal of the SOS however is not to produce a nice report but to have impact and improve the security of the respective system! Recommended solution: - Identify „Systematic Issues“ (e.g. issues with the authorization concept) and trigger a solution - Identify „Top Issues“ and solve them first! - Identify „Quick Wins“ and implement them - Determine the remaining risk and - either address the next set of „Top Issues“ - or get agreement, that the achieved level of security looks acceptable until the next scheduled run of the SOS **Action Definition Template** <table> <thead> <tr> <th>Name / Identification of the Action</th> <th></th> </tr> </thead> <tbody> <tr> <td>Short summary of the issue</td> <td></td> </tr> <tr> <td>Required Actions</td> <td></td> </tr> <tr> <td>Who</td> <td>By When</td> </tr> <tr> <td>tbd</td> <td>tbd</td> </tr> </tbody> </table> *Use the standard procedure that works best in your environment for defining, assigning and tracking actions. This can be issues / top issues in the Solution Manager, some ticketing system or a manual process based on Word, PowerPoint, Outlook or something else.* Further Information and Contact Contact address SecurityCheck@sap.com Public information SAP Service Marketplace, using alias /SOS http://service.sap.com/sos SAP Notes: • Note 696478 - SAP Security Optimization: Preparation & Additional Info • Note 837490 - Execution of the Security Optimization Self-Service • Note 863362 - Security Checks in the SAP EarlyWatch Alert Related SAP education training opportunities • http://www.sap.com/education Search for ADM960: Security in SAP system environments Security Optimization Service: EGI session Get in-depth knowledge of the Security Optimization Service functionality with the Expert Guided Implementation (EGI) service. The EGI gives the participants the opportunity to set up ready-to-use Security Optimization Reports in their own SAP Solution Manager. Training, practical experience, remote consulting **Empowering**, Web session, 1-2 h. each morning SAP expert explains step-by-step configuration using training materials **Execution**, 2-3 h. on the same day Participants execute demonstrated steps within their own project, on their own SAP environment Expertise on demand, during execution Participants have direct access to an SAP expert who directly supports them remotely, if necessary, during the execution More information on available EGI topics and booking information can be found here: https://service.sap.com/esacademy ⇒ EGI Registration EGI for Security Optimization Exercises Security Optimization Service report Agenda ➤ Best Practices-based Services Security Tools and Services ➤ EarlyWatch Alert (EWA) – Security Chapter ➤ Security Notes Report (RSECNOTE) ➤ System Recommendations ➤ Security Optimization Service (SOS) ➤ Configuration Validation ➤ Run SAP Standard for Security Appendix ➤ SAP Enterprise Support Report Consider Customers Situation of Today … **Challenges** - A large number of systems… Complex SAP Landscape … - … Need to perform comparison of current configuration status against a defined target or standard configuration baselines - … with minimum efforts and ASAP End-to-End Diagnostics and SAP Solution Manager End-to-End Reporting Prove value to business End-to-End Monitoring and Alerting Automate operations End-to-End Root Cause Analysis Lower mean time to resolution Component specific Root Cause Analysis SAP SOLUTION MANAGER - SAP EarlyWatch Alert - Service Level Reporting - Customer BI Reporting System Monitoring End-user Monitoring Interface Monitoring Job Monitoring Business Process Monitoring Unified Alert Inbox Alert correlation and propagation Open data provider and alert consumer End-to-End Change Analysis - End-to-End Workload Analysis - End-to-End Exception Analysis - End-to-End Trace Analysis E2E Change Analysis is the main prerequisite for Configuration Validation MANAGED SYSTEMS ABAP Java .NET C(++) © 2012 SAP AG. All rights reserved. Configuration Validation Architecture Overview Solution Manager EHP1 Configuration Validation - Virtual InfoProvider OSMD_VCA1 - Function Module - Configuration and Change Database (CCDB) - DB Table - Target System Maintenance - Configuration Validation Reporting - Change Reporting - Interactive BI based Reporting - Manual maintenance of copied configuration data - Copy - Customer defined system configurations / baselines - Existing system configurations JAVA based installations - Diagnostics Agents ABAP based installations - Solution Tool Plugins - Extractor Framework (EFWK) Once a day - Solution Tool Plugins Configuration Compliance Report - Security Overview © 2012 SAP AG. All rights reserved. ## Content Deliverables – Configuration Items Overview <table> <thead> <tr> <th>Application</th> <th>Software Release Validation</th> <th>Parameter Validation</th> </tr> </thead> <tbody> <tr> <td></td> <td>• Support Package Stack</td> <td>• SAP Product specific settings</td> </tr> <tr> <td></td> <td>• Software Component Versions</td> <td>- PI/XI specific configuration</td> </tr> <tr> <td></td> <td>• Implemented SAP Notes</td> <td>- BI specific configuration</td> </tr> <tr> <td></td> <td>• Imported ABAP Transports</td> <td>- BIA specific configuration</td> </tr> <tr> <td>Kernel</td> <td>• Web AS ABAP Kernel Release</td> <td>• ABAP Instance Parameters</td> </tr> <tr> <td></td> <td>• Java VM version</td> <td>- Java VM parameters for J2EE</td> </tr> <tr> <td></td> <td>• Web AS Java Release</td> <td>Database Parameters</td> </tr> <tr> <td>Database</td> <td>• Database Release</td> <td>Operating System Parameters</td> </tr> <tr> <td>Operating System</td> <td>• Operation System Release</td> <td>Operating System Environment Settings</td> </tr> <tr> <td>Security</td> <td></td> <td>Standard Users</td> </tr> <tr> <td></td> <td></td> <td>Gateway Secinfo</td> </tr> <tr> <td></td> <td></td> <td>Gateway Reginfo</td> </tr> </tbody> </table> Possible Reference Systems / Configuration Baselines 1. Reference is an Existing System - Data stored in Configuration and Change Database (CCDB) - Latest available snapshot used for comparison - No changes of configuration items are allowed 2. Reference is a Target System - Content of existing configuration is copied into a separate database table - Copied configuration items can be edited to match a specific audit task - Reference system should contain a restricted number of configuration items Configuration Validation Target System Maintenance ## Configuration Validation ### Drilldown Reporting ### Configuration Compliance - Selected Items of one ConfigStore <table> <thead> <tr> <th>Reference System</th> <th>SMX 0020253585</th> </tr> </thead> <tbody> <tr> <td>Comparison Systems</td> <td>B35 0020144209, B70 0020261098, C50 0020108503, C50 0020182324, C70 SAP-INTERN, ESU 0120021077</td> </tr> <tr> <td>Config Store</td> <td>ΔBAP_INSTANCE_PAHI</td> </tr> <tr> <td>Configuration Item</td> <td>login/fails_to_user_lock, login/min_password_ing, login/no_automatic_user_sapstar</td> </tr> </tbody> </table> <table> <thead> <tr> <th>System</th> <th>Instance Name</th> <th>Configuration Item</th> <th>Config. Item Value</th> <th>Target Value</th> <th>Last Check [UTC]</th> <th>Compliant (1=yes, 0=no)</th> </tr> </thead> <tbody> <tr> <td>SMX 0020253585</td> <td>D00</td> <td>login/fails_to_user_lock</td> <td>5</td> <td>#</td> <td>20100909200301</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/min_password_ing</td> <td>6</td> <td>#</td> <td>20100909200301</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/no_automatic_user_sapstar</td> <td>1</td> <td>#</td> <td>20100909200301</td> <td>1</td> </tr> <tr> <td></td> <td>DVEBMGS00</td> <td>login/fails_to_user_lock</td> <td>5</td> <td>#</td> <td>20100909200300</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/min_password_ing</td> <td>6</td> <td>#</td> <td>20100909200300</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/no_automatic_user_sapstar</td> <td>1</td> <td>#</td> <td>20100909200300</td> <td>1</td> </tr> <tr> <td>B35 0020144209</td> <td>DVEBMGS00</td> <td>login/fails_to_user_lock</td> <td>12</td> <td>5</td> <td>20100323200608</td> <td>0</td> </tr> <tr> <td></td> <td></td> <td>login/min_password_ing</td> <td>3</td> <td>6</td> <td>20100323200608</td> <td>0</td> </tr> <tr> <td></td> <td></td> <td>login/no_automatic_user_sapstar</td> <td>0</td> <td>1</td> <td>20100323200608</td> <td>0</td> </tr> <tr> <td>B70 0020261098</td> <td>DVEBMGS21</td> <td>login/fails_to_user_lock</td> <td>5</td> <td>5</td> <td>20100909200302</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/min_password_ing</td> <td>6</td> <td>6</td> <td>20100909200302</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/no_automatic_user_sapstar</td> <td>0</td> <td>1</td> <td>20100909200302</td> <td>0</td> </tr> <tr> <td>C50 0020108503</td> <td>DVEBMGS00</td> <td>login/fails_to_user_lock</td> <td>10</td> <td>5</td> <td>20081019105001</td> <td>0</td> </tr> <tr> <td></td> <td></td> <td>login/min_password_ing</td> <td>6</td> <td>6</td> <td>20081019105001</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>login/no_automatic_user_sapstar</td> <td>0</td> <td>1</td> <td>20081019105001</td> <td>0</td> </tr> <tr> <td>C60 0020182324</td> <td>DVEBMGS00</td> <td>login/fails_to_user_lock</td> <td>5</td> <td>5</td> <td>20100909193657</td> <td>1</td> </tr> </tbody> </table> Configuration Validation Predefined Security Report in Solution Manager 7.0 (discontinued) Introducing operators offers a greater flexibility to define a fitting target system. New with Solution Manager 7.1 Operators and Target Systems In Solution Manager 7.1 all rules are transparent and no rules are hardcoded Operators available for all types of Config Stores: property, table, text, and xml Operators comprise the rule used for validation for a Config Item New with Solution Manager 7.1 SAP Notes: based on RSENCNOTE / System Recommendations Option b) all notes based on System Recommendations ABAP_NOTES and JAVA_NOTES of a Target System can be filled with: - System recommendations which are the SAP Notes relevant for the source system - Online recommendations which are the SAP Notes from SAP Security List Option a) ABAP security notes based on RSENCNOTE New with Solution Manager 7.1 ABAP Notes – based on recommendations from RSECNOTE Option a) ABAP security notes based on RSECNOTE The SAP Notes from the SAP Security List - Software and Kernel dependency of a Note is provided - Only relevant SAP Notes for the source system can be inserted (the SAP Notes matching Components and Kernel Release from the source system) New with Solution Manager 7.1 ABAP/Java Notes – based on System Recommendations Option b) all notes based on System Recommendations The SAP Notes relevant for the source system can be restricted via • Data Range • Note Group – for example only Security and Hotnews SAP Notes can be inserted New with Solution Manager 7.1 SP 2 Use Case – Predefined Report about Security Notes from RSECNOTE New with Solution Manager 7.1 SP 2 Use Case – Predefined Report about Security Notes from RSECNOTE **Selected ConfigStores and Items** - Only Non compliant Items with Value and Target Value ``` Selection: Reference and Comparison System, Config Store and Item(s) DGRT001VIRTUAL, SD7 0020270862, S17 0020270862, SQ7 0020230702, ST7 0020270862, SW7 0020270862, SD7, S17, SQ7, ST7 ``` ### Configuration Items <table> <thead> <tr> <th>Config Item</th> <th>System</th> <th>Compliance</th> <th>Last Check [UTC]</th> <th>Compliant (1=Yes, 0=No, '-'=Not valued)</th> </tr> </thead> <tbody> <tr> <td>0001490437</td> <td>SQ7 0020230702</td> <td>No</td> <td>20110609180215</td> <td>0</td> </tr> <tr> <td>0001556749</td> <td>SD7 0020270862</td> <td>No</td> <td>20110609181329</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>S17 0020270862</td> <td>No</td> <td>20110609181407</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>SQ7 0020230702</td> <td>No</td> <td>20110609180215</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>ST7 0020270862</td> <td>No</td> <td>20110609180158</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>SD7 0020270862</td> <td>No</td> <td>20110609181329</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>S17 0020270862</td> <td>No</td> <td>20110609181407</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>SQ7 0020230702</td> <td>No</td> <td>20110609180215</td> <td>0</td> </tr> <tr> <td>0001556649</td> <td>ST7 0020270862</td> <td>No</td> <td>20110609180158</td> <td>0</td> </tr> </tbody> </table> BUCHHOLZF, 10.06.2011 08:51:46 New with Solution Manager 7.1 Critical User Authorizations: Config Stores in CCDB - **AUTH_CHECK_USER** User authority check store - **AUTH_PROFILE_USER** User profile check store - **AUTH_TRANSACTION_USER** User transaction check store **Example:** Store Content of AUTH_PROFILE_USER <table> <thead> <tr> <th>History</th> <th>PROFILE</th> <th>USER</th> <th>RESULT</th> </tr> </thead> <tbody> <tr> <td>SAP_ALL</td> <td></td> <td>ADSUSER</td> <td>USER IS AUTHORIZED</td> </tr> <tr> <td></td> <td></td> <td>AGRAM/WALKA</td> <td>USER IS AUTHORIZED</td> </tr> <tr> <td></td> <td></td> <td>ALEREMOTE</td> <td>USER IS AUTHORIZED</td> </tr> <tr> <td></td> <td></td> <td>AMRAM</td> <td>USER IS AUTHORIZED</td> </tr> </tbody> </table> New with Solution Manager 7.1 Critical User Authorizations: Customizing Store Content CCDB Administration tool allows to customize those store contents - Call transaction **CCDB** to start CCDB Administration tool - Navigate to tab “**Technical Systems**” - Select system and display stores relevant for user critical authorizations - Navigate to tab “**Customizing**” - Create new customizing variant and adjust it accordingly (by default only users with SAP_ALL role are tracked) New with Solution Manager 7.1 Critical User Authorizations: Analysis of user profiles **AUTH_PROFILE_USER**: User profile check store in the Target System (reference) defines that no user is allowed to have SAP_ALL profile **Validation Output**: The Users which have critical authorizations in the system SI7 (compared system) New with Solution Manager 7.1 Critical User Authorizations: Analysis of user authorizations **AUTH_CHECK_USER**: User authorizations check store in the Target System (reference) defines that only certain admin users are allowed to have debug authorizations **Validation Output**: Users which have the critical debug authorizations in the system SD7 (compared system) can be easily found New with Solution Manager 7.1 Critical User Authorizations: Analysis of user transactions **AUTH_TRANSACTION_USER:** User transaction check store in the Target System (reference) defines that only admin users are allowed to have authorizations for the transaction SM59 **Validation Output:** The Users which are not allowed to have the authorizations for Configuration RFC in the system SD7 (compared system) can be easily found. New with Solution Manager 7.1 RFC Hopping: Overview Risk of RFC Hopping with RFC Destinations Privilege Escalation User impersonation Bypass Network Firewalls Hop through the whole system landscape (e.g. jump to a central system like the SolMan) Countermeasure Identify critical RFC Destinations across systems Identify RFC Destinations to critical systems User Authorizations User ABC with restricted permissions User XYZ with SAP_ALL permissions User EWA with restricted permissions User AWE with SAP_ALL permissions New with Solution Manager 7.1 RFC Hopping: Store RFCDES_TYPE_3_CHECK **RFCDES_TYPE_3_CHECK**: For each RFC Destinations it is checked if the user provided in this RFC Destination has critical authorizations and/or can be used for login. **CV_USER_PROFILE_RESULT** - **CRITICAL_USER_PROFILE** – User provided exists in destination System and has critical authorizations - **OK_USER_NOT_IN_PROFILE_STORE** - User provided exists in destination System but does not have critical authorizations - **OK_NO_USER_OR_PW_IN_RFCDEST** - No user and/or no pw is stored in the destination RFC Hopping: Target System to find all critical RFC Destinations RFCDES>Type_3_CHECK: This Store has been reduced up to one record and defines the pattern to search all RFC Destinations with critical status. New with Solution Manager 7.1 RFC Hopping: Output with critical RFC Destinations **0TPL_0SMD_VCA2_NCOMPL_CI_REF**: This report shows all the RFC Destinations with critical status. The critical user authorizations could be customized via the `AUTH_PROFILE_USER` Store (by default the users with the profile “SAP_ALL” is checked). ### Validation Details: In the column “Comparison Value” you can find all the details on the critical RFC Destination. In our example for the RFC Destination “PMIB4X001” which is created in the system B4X the user “PIRWBUSER” and the password saved in the logon data. This user has the profile “SAP_ALL” assigned in the system B4X. RFCDES_TYPE_3_CHECK: This Store has been reduced up to one record and defines the pattern to search all RFC Destinations pointing to the System SI7. New with Solution Manager 7.1 RFC Hopping: Output with the RFC Destinations pointing to a critical System **0TPL_0SMD_VCA2_CITEMS_REF:** This Report displays validation results for all RFC Destinations. **Filter:** Select filter value “Yes” for column “Compliance” to display only the RFC Destinations pointing to the critical system. New with Solution Manager 7.1 UI: Security Template The new Security Template: - Supports customer to have a head start when starting with configuration validation towards security. It contains suggestion for rules and values for a number of Config Stores and can be used to create a target system. - It’s possible to add or remove Config Stores and to change rules and values. New with Solution Manager 7.1 Security Template: Examples of Store Definition **MS_SECINFO** <table> <thead> <tr> <th>Line Content</th> <th>Operator</th> <th>Operator Pattern</th> </tr> </thead> <tbody> <tr> <td>Line OK</td> <td>Regex</td> <td>HOST=[&quot;]*</td> </tr> <tr> <td>Line not OK</td> <td>Not regex</td> <td>HOST=[&quot;</td> </tr> </tbody> </table> The definition means that the entry HOST=* which is the default entry used in a system in case no message server ACL is defined is validated as NON compliant. **GW_SECINFO** <table> <thead> <tr> <th>Line Content</th> <th>Operator</th> <th>Operator Pattern</th> </tr> </thead> <tbody> <tr> <td>USER OK</td> <td>Regex</td> <td>&quot;USER=[&quot;]*</td> </tr> <tr> <td>USER-HOST OK</td> <td>Regex</td> <td>&quot;USER-HOST=[&quot;]*</td> </tr> <tr> <td>HOST OK</td> <td>Regex</td> <td>&quot;HOST=[&quot;]*</td> </tr> <tr> <td>TP OK</td> <td>Regex</td> <td>&quot;TP=[&quot;]*</td> </tr> <tr> <td>Line not OK</td> <td>Not(Regex</td> <td>&quot;USER=[&quot;]* USER-HOST=[&quot;]* HOST=[&quot;]* TP=[&quot;]*</td> </tr> </tbody> </table> This definition is to validate all lines that use only parameters with the * as non compliant which would be the same result as the validation of EhP1, see SAP note 1234799. **SICF_SERVICES** In a SAP system only the really needed services for the SAP Internet Communication Framework (ICF) should be active. New with Solution Manager 7.1 Security Template: Examples of Store Definition **STANDARD_USERS** <table> <thead> <tr> <th>CLIENT</th> <th>USER</th> <th>PASSWORD_STATUS</th> <th>EXISTS</th> <th>LOCKED</th> </tr> </thead> <tbody> <tr> <td>( Contains ) *</td> <td>( = ) DDC</td> <td>( Not equal ) DEFAULT</td> <td>( Ignore ) X</td> <td>( Ignore )</td> </tr> <tr> <td>( Contains ) *</td> <td>( = ) EARLYWATCH</td> <td>( Not equal ) DEFAULT</td> <td>( Ignore ) X</td> <td>( Ignore )</td> </tr> <tr> <td>( Contains ) *</td> <td>( = ) SAP*</td> <td>( Not equal ) DEFAULT</td> <td>( = ) X</td> <td>( Ignore )</td> </tr> <tr> <td>( Contains ) *</td> <td>( = ) SAPCPC</td> <td>( Not equal ) DEFAULT</td> <td>( Ignore ) X</td> <td>( Ignore )</td> </tr> <tr> <td>( Contains ) *</td> <td>( = ) TMSADM</td> <td>( Not equal ) DEFAULT</td> <td>( Ignore ) X</td> <td>( Ignore )</td> </tr> </tbody> </table> The Password status should not be DEFAULT. The user SAP* must exist in all clients and its password must be changed. For the other users there is no need to be existent in all clients. **ABAP_INSTANCE_PAHI** The definition covers parameters that are validated also by the security optimization services (SOS). The Regex for login/ticket_expiration_time means less than 12 hours would be compliant. New with Solution Manager 7.1 E2E Alerting It’s possible to add a target system to E2E Alerting. Non-compliant items could then cause an alert within the alert inbox (System alert: configuration validation) New with Solution Manager 7.1 SP 3 Management Dashboard WebDynpro ABAP Application **MY_DASHBOARD** The dashboard apps show the validation results of the comparison of selected systems with a target system. Further Information and Contact Configuration Validation Configuration Validation @ Service Market Place https://service.sap.com/diagnostics → END-TO-END ROOT CAUSE ANALYSIS Demos Presentations Configuration Guide (goon in folder ‘media library’) Configuration Validation @ SDN http://wiki.sdn.sap.com/wiki/display/TechOps/ConfVal_Overview http://wiki.sdn.sap.com/wiki/display/TechOps/ConfVal_Home Best Practice Configuration Validation: EGI session Get in-depth knowledge of the Configuration Validation functionality with the Expert Guided Implementation (EGI) service. The EGI gives the participants the opportunity to set up ready-to-use Configuration Validation Reports in their own SAP Solution Manager. Training, practical experience, remote consulting **Empowering**, Web session, 1-2 h. each morning SAP expert explains step-by-step configuration using training materials **Execution**, 2-3 h. on the same day Participants execute demonstrated steps within their own project, on their own SAP environment **Expertise on demand**, during execution Participants have direct access to an SAP expert who directly supports them remotely, if necessary, during the execution More information on available EGI topics and booking information can be found here: https://service.sap.com/esacademy ➔ EGI Registration Demo Configuration Validation Configuration Validation SAP Solution Manager Workcenter – Change Management Quicklink for Easy Access Menu: WebDynpro ABAP DIAGCPL_VIRT_SYS Configuration Validation Maintain Target System – Create with Template ![Configuration Validation Screen](image) - **Source System** - **System ID**: [Blank] - **System Type**: [Blank] - **Store Name**: [Blank] - **Store Type**: [Blank] - **Search String**: [Blank] - **Select Source Systems** - [Create with Template] - **Select Config Stores** - **Name**: sapscu - **Group**: HARDWARE - **Category**: CONFIG - **Type**: XML - **Host**: wdflbrmt0698 - **Component Version**: 000000000010 - **Landscape ID**: wdflbrmt0698 - **Additional Config Stores** - AUTH PROFILE USER - AUTH_CHECK_USER - AUTH_TRANSACTION_USER - ADAP_INSTANCE_PAI - GW_REGINFO - GW_SECINFO - PSE_CERT - ABAP_START_PROFILE - ABAP_INSTANCE_PROFILE - ENV VARIABLES Configuration Validation Maintain Target System – Create with Template Create Target System from a Template - System ID: SEC_00 - Description: Security Validation Target for customer #00 Select Template / Target System - Display SAP Templates - Display mnr Target Systems <table> <thead> <tr> <th>Name</th> <th>Description</th> <th>Created by</th> </tr> </thead> <tbody> <tr> <td>0DI</td> <td>Template for UTPL_0SMO_COMPL_SLS...</td> <td></td> </tr> <tr> <td>0CB</td> <td>Template for UTPL_0SMO_COMPL_OB...</td> <td></td> </tr> <tr> <td>OREF_COM</td> <td>Reference Template for Communication...</td> <td></td> </tr> <tr> <td>OREF_VEM</td> <td>Reference Template for Memory Config...</td> <td></td> </tr> <tr> <td>0SEC</td> <td>Template for UTPL_0SMO_COMPL_SEC...</td> <td></td> </tr> <tr> <td>0SEC_NEW</td> <td>New Definition for 0SEC</td> <td>SAP</td> </tr> <tr> <td>0SW</td> <td>Template for UTPL_0SMO_COMPL_SW...</td> <td></td> </tr> </tbody> </table> Read the store list from Template and copy the same stores from source system. Leave the content of copied stores unchanged! Create ### Configuration Validation #### Maintain Target System – Edit Target Values **Target System Maintenance** - Create - Edit **Target System** - **Long SID:** - **Description:** - **Store Type:** - **Owner:** - **Customer Target Systems** - **SAP Target Systems** **Select Target System** - **SID** - **Description** - **ConfStores of Target System: SEC_00** - **Store Name** - **Type** - **Group** - **Instance Type** - **STANDARD_USERS** - **TABLE** - **ABAP-SECURITY** - **AUTH_PROFILE_USER** - **TABLE** - **USER-AUTH...** - **SICF_SERVICES** - **TABLE** - **ABAP-SECURITY** - **MS_5EINFO** - **TABLE** - **ABAP-SECURITY** - **ABAP_NOTES** - **TABLE** - **ABAP-SOFTWARE** - **GW_REGINFO** - **TEXT** - **INSTANCE** - **DIALOG** - **GW_SECINFO** - **TEXT** - **INSTANCE** - **DIALOG** - **ABAP_INSTANCE_PAHI** - **PROPERTY** - **INSTANCE** - **CENTRAL** - **SAP_KERNEL** - **PROPERTY** - **INSTANCE** - **CENTRAL** - **GLOBAL** - **PROPERTY** - **SYSTEM-CHAN...** © 2012 SAP AG. 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Excess open solar magnetic flux from satellite data: 2. A survey of kinematic effects Article Published Version It is advisable to refer to the publisher’s version if you intend to cite from the work. Published version at: http://dx.doi.org/10.1029/2009JA014450 To link to this article DOI: http://dx.doi.org/10.1029/2009JA014450 Publisher: American Geophysical Union All outputs in CentAUR are protected by Intellectual Property Rights law, including copyright law. Copyright and IPR is retained by the creators or other copyright holders. Terms and conditions for use of this material are defined in the End User Agreement. www.reading.ac.uk/centaur CentAUR Central Archive at the University of Reading Reading's research outputs online Excess open solar magnetic flux from satellite data: 2. A survey of kinematic effects M. Lockwood,1,2 M. Owens,3 and A. P. Rouillard1,2 Received 12 May 2009; accepted 22 July 2009; published 12 November 2009. [1] We investigate the “flux excess” effect, whereby open solar flux estimates from spacecraft increase with increasing heliocentric distance. We analyze the kinematic effect on these open solar flux estimates of large-scale longitudinal structure in the solar wind flow, with particular emphasis on correcting estimates made using data from near-Earth satellites. We show that scatter, but no net bias, is introduced by the kinematic “bunching effect” on sampling and that this is true for both compression and rarefaction regions. The observed flux excesses, as a function of heliocentric distance, are shown to be consistent with open solar flux estimates from solar magnetograms made using the potential field source surface method and are well explained by the kinematic effect of solar wind speed variations on the frozen-in heliospheric field. Applying this kinematic correction to the Omni-2 interplanetary data set shows that the open solar flux at solar minimum fell from an annual mean of $3.82 \times 10^{16}$ Wb in 1987 to close to half that value ($1.98 \times 10^{16}$ Wb) in 2007, making the fall in the minimum value over the last two solar cycles considerably faster than the rise inferred from geomagnetic activity observations over four solar cycles in the first half of the 20th century. 1. Introduction [2] In our companion paper [Lockwood et al., 2009] (hereinafter referred to as paper 1), we discussed the Ulysses result of the latitudinal invariance of the radial heliospheric field and its relationship to the “flux excess” detected by Owens et al. [2008a]. As given in paper 1, using the latitudinal invariance gives the signed open flux (of one polarity), $F_S$, to be $$F_S = 2\pi r^2 \langle |B_r|/T \rangle_{CR}$$ \hspace{1cm} (1) where $r$ is the heliospheric distance and $B_r$ is the radial component of the heliospheric field. The subscript CR is to denote that the averages are taken over a Carrington Rotation interval (or alternatively a Bartels rotation interval) to remove longitudinal structure. $T$ is the timescale on which $B_r$ data are preaveraged and then converted into absolute values. Lockwood et al. [2004] showed that the error introduced into $F_S$ by use of equation (1) was <5% if averages over a 27 days or longer are taken: this was shown to be true for both solar maximum and solar minimum conditions. [3] Recently Owens et al. [2008a] have studied the open solar flux (in fact, they studied the unsigned flux; i.e., $2F_S$) deduced from spacecraft in different parts of the heliosphere using $T = 1$ h. They find considerable agreement between the data sequences from different craft which gives strong support to the use of equation (1). However, although they find that neither latitudinal nor longitudinal separation of the craft introduced significant differences on average, they did find a consistent increase in the estimated $F_S$ with heliocentric distance $r$, which became especially pronounced at above about 2.5 AU. This “flux excess” effect was discussed in relation to the third Ulysses perihelion pass in paper 1. Although the survey by Owens et al. [2008a] did not find a consistent variation of the excess flux with heliographic latitude $\Lambda$, these authors noted that any variation with $\Lambda$ in Ulysses data was convolved with the dependence on $r$ owing to the nature of the satellite’s orbit. In fact, these data are further complicated by the sunspot cycle phase $\varepsilon$ which changes on timescales comparable to the Ulysses orbital period; separation of the effects of $r$, $\Lambda$ and $\varepsilon$ are presented by Lockwood and Owens [2009]. In paper 1 we report a difference between the excess flux in the streamer belt and the large polar coronal holes for the third pass of Ulysses which was near solar minimum. [4] The open solar flux (here defined as the flux threading the coronal source surface) has also been evaluated from solar magnetograms using the potential field source surface (PFSS) method [e.g., Schatten et al., 1969; Altschuler and Newkirk, 1969; Schatten, 1999]. In this method, the observed photospheric magnetic fields from a magnetogram 1Space Environment Physics, School of Physics and Astronomy, Southampton University, Southampton, UK. 2Also at Space Science and Technology Department, Rutherford Appleton Laboratory, Chilton, UK. 3Space and Atmospheric Physics Group, Blackett Laboratory, Imperial College London, London, UK. Copyright 2009 by the American Geophysical Union. 0148-0227/09/2009JA01445009.00 are mapped through the solar corona to the source surface (assumed to be spherical with radius \( r = r_o = 2.5 \) solar radii = \((2.5/251)\)AU, where 1 AU \( \approx 1.5 \times 10^{11} \) m) with a number of assumptions. Agreement with data from situ observations of the heliospheric field has generally been good [Wang and Sheeley, 2003], but two caveats to this comparison should be noted. First, the magnetogram data require processing using a latitude-dependent instrument saturation factor [Wang and Sheeley, 1995] which has been the subject of some debate [Svalgaard et al., 1978; Ulrich, 1992]. Second, for the satellite data taken near Earth (at heliocentric distance \( r \approx 1 \) AU), preaveraging of \( B_r \) on timescales of \( T = 1–2 \) days (before absolute values are taken) has been required: otherwise the latter would show a flux excess (relative to the PFSS values). As discussed in paper 1, the idea is that the value of \( T \) is chosen so that it is not so large that the opposing field in “toward” and “away” interplanetary sectors of the source field are canceled (which would cause the true open solar flux to be underestimated) but should be large enough that small-scale structure generated in the heliosphere (which does not reflect structure in the source field and so would cause the true open flux to be overestimated) is averaged out. Increasing \( T \) results in lower \( F_S \) values given by equation (1) [Lockwood et al., 2006], but there is no a priori reason for adopting any one value of \( T \). At any one time, there will always be a \( T \) for which the near-Earth estimate using equation (1) will equal the true coronal source flux, but without an understanding of how to compute it, we cannot be sure of the correct \( T \) to use nor if it is constant with either time or heliographic coordinates. Indeed, it may be that the heliospheric effects cannot be separated from source sector structure by their timescales, in which case the use of \( T \) has no physical justification at all. A value for \( T \) of 1 day has commonly been adopted because it has given a good general match of the variations in \( F_S \) deduced from near-Earth in situ data to those from the PFSS method [Wang and Sheeley, 1995; Wang et al., 2000; Lockwood et al., 2006]. [5] Paper 1 analyzed the effect of various \( T \), and of plasma time-of-flight associated with large-scale longitudinal solar wind variability (“kinematic effects”; see section 2), on the flux excess detected by comparison of data from the near-Earth ACE satellite with that from the Ulysses spacecraft during its third perihelion pass. Paper 1 found that both effects provided a partial allowance for the flux excess, although the kinematic correction performed more satisfactorily in a number of respects. However, it also showed that these are not equivalent corrections in that the kinematic correction is allowing for larger-scale structure in the heliosphere (giving variations at any one point on timescales 1–27 days) whereas the averaging timescale can only make allowance for smaller-scale structure (on timescales of \( T \leq 1 \) day). Furthermore, paper 1 showed that structure on timescales \( T < 1 \) h was not contributing to the observed flux excess because its effect was the same at all \( r \) and \( \Lambda \). The averaging and the kinematic corrections generated somewhat different estimates of the open solar flux \( F_S \). The kinematic correction gave a more uniform variation of the radial field with latitude and gave closer agreement between the ACE and Ulysses data (but not by an overwhelmingly large factor). One major advantage of the kinematic correction was that it matched a difference between the streamer belt and the sunspot-minimum polar coronal hole, whereas averaging over a fixed time interval \( T \) did not. In the present paper, we consider the kinematic correction of coronal source flux estimates from \( r \) near 1 AU and elsewhere in the heliosphere and show it to be consistent, not only with the flux excess variation as a function of \( r \) in the inner heliosphere as deduced by Owens et al. [2008a], but also with PFSS open flux estimates. 2. Theory of Kinematic Effects [6] Figure 1 is a schematic of how large-scale temporal (Figures 1a–1c) and spatial (Figures 1d–1f) structure in the radial solar wind flow speed can give rise to excess flux via purely kinematic (time-of-flight) effects and how this excess flux grows with heliocentric distance \( r \). In both cases, this arises because the field becomes distorted as it is frozen into the longitudinally variable flow. Both spatial and temporal effects result in the excess flux in measurements made at \( r \approx r_1 = 1 \) AU which therefore need correcting for these kinematic effects. As suggested by comparison of Figures 1c and 1f, it will not be easy to distinguish the spatial and temporal effects in many cases, as both result in an amplification of the magnitude of the ambient radial field in regions of increasing solar wind speed \( V \) (\( dV > 0 \) and a reduction (and, at sufficiently large \( r \), a reversal in polarity) in regions of decreasing solar wind speed \( dV < 0 \). Examples of such kinematic effects have been reported in the streamer belt: Riley and Gosling [2007] have shown that events of near-radial IMF reported by Jones et al. [1998] are explained by the kinematic effect in rarefaction regions where the solar wind velocity decays \( dV < 0 \). Burlaga and Barouch [1976] provided equations which quantify the effects shown schematically in Figure 1. It is important to note that these equations do not allow for dynamical stream–stream interactions that will inevitably accompany the kinematic effects associated with increasing solar wind flow speeds in compression regions (\( dV > 0 \)) [Gosling, 1996; Gosling and Pizzo, 1999; Arge and Pizzo, 2000]. Compression regions steepen as they propagate to greater \( r \), until shocks form. However, the lack of dynamical effects in rarefaction regions means that the kinematic effects will grow with increasing \( r \) until the IMF becomes radial [Jones et al., 1998; Riley and Gosling, 2007]. [7] Burlaga and Barouch [1976, equation (16)] gives the vector field at a heliocentric distance \( r \) for purely kinematic effects: \[ \mathbf{B} = \left\{ (r_o/r)^2 B_{r_0} + \Delta B_r \right\} \mathbf{r} + \mu B_{\varphi 0}(r_o/r) \mathbf{\varphi} \] (2) where \[ \Delta B_r = [\partial V/\partial r_o] \frac{\mu (r - r_o)}{\Omega r_o V \cos \lambda} (r_o/r)^2 B_{\varphi 0} \] (3) \( B_{r_0} \) and \( B_{\varphi 0} \) are the radial and longitudinal components of the field at the coronal source surface \( r = r_o \), \( \lambda \) is the heliographic latitude, \( \Omega \) is the angular rotation velocity of the solar atmosphere, \( V \) is the (radial) solar wind speed and \( \mu \) is a dimensionless parameter that allows for the kinematic steepening of gradients owing to time-of-flight effects: it If we consider initially only kinematic effects; that is, with no modification of the solar wind velocity vector \( V \) by stream-stream interactions, the radial velocities \( V \) and \( V + dV \) observed at \( r \) (at times \( t \) and \( dt \)) will be the same for those plasma parcels at all \( r \). Plasma parcels seen \( dr \) apart at \( r \) will have left the coronal source surface at an interval \( dr_o \) apart. Defining the times-of-flight for the radial velocities \( V \) and \( V + dV \) to be \( \tau_V \) and \( \tau_{V+dV} \): \[ dr_o = dt + \tau_V - \tau_{V+dV} = dt + \left( \frac{r - r_o}{V} \right) - \left( \frac{r - r_o}{V + dV} \right) \] (6) Thus \( \frac{dV}{dt} \) can be computed as all the terms on the right-hand side of equation (5) are known from the spacecraft data at \( r \). Hence \( \Delta B_r \) can be predicted from solar wind and IMF observations at \( r \) (for the kinematic assumption of constant \( V \)). The gray histogram in Figure 2 shows the distribution of \( \Delta B_r \) values computed using equations (5) and (6) from hourly observations taken near Earth \( (r = r_1 = 1 \text{ AU}) \) between 1963 and 2008 as compiled in the Omni-2 data set of hourly interplanetary averages (the continuation of the work of Couzens and King [1986]). [s] In compression regions where solar wind speeds increase at any one latitude \( (dV > 0) \), dynamical stream-stream interaction regions form on the leading boundaries of coronal holes [Cranmer, 2002] where fast wind catches up with slow wind ahead of it and the assumption of constant \( V \) becomes invalid. These flow gradients steepen as they propagate outward but do not generally form shocks until \( r \approx 2 \text{ AU} \) [e.g., Gosling, 1996]. Such interaction regions at \( r = 1 \text{ AU} \) typically last on the order of 1 day [e.g., Gosling and Pizzo, 1999]. To remove their effect on the kinematic correction, we here use smoothed values of \( V \); daily means in \( dV \) are interpolated to apply at the centers of the hourly averaging intervals of the IMF data. The smoothing time constant of 1 day represents a compromise: it smoothes out much of the dynamical effects in interaction regions but the overall autocorrelation function of the solar wind speed at 1 AU falls to 0.5 for lags near 30 h [Lockwood, 2002], hence using intervals any longer than 1 day would cause us to also average out considerable larger-scale longitudinal structure in the source solar wind speed. The use of 1 day smoothing means that we are predicting the kinematic effects of flow speed structure on timescales of 1–27 days. The effectiveness of this procedure to remove dynamic interaction effects in compression regions is discussed later in section 2. [9] From equation (6), Burlaga and Barouch [1976] show that the parameter \( \mu \) is given by \[ \mu = \left[ 1 - \frac{r - r_o}{\frac{dV}{dt} \mid_{r_o}} \right] \frac{1}{V^2} \] (7) Hence computation of \( \mu \) as a function of \( r \) requires knowledge of the ratio \( \frac{dV}{dt} \mid_{r_o} \). This ratio is shown in Figure 3 for the same data set as Figure 2. Positive values are compression regions \( (\frac{dV}{dt} \mid_{r_o} > 0) \) which give \( dr < dr_o \), negative values are rarefaction regions \( (\frac{dV}{dt} \mid_{r_o} < 0) \) which give \( dr > dr_o \). Note that \( V \) values have been given in units of AU s\(^{-1}\) as this gives ready application with \( r \) values expressed in units of AU. Studying equations (4) and (7) highlights the limitations of this theory in compression regions. At sufficiently large \( r \), \((r_0/r_1)^2 [B_r]_0 \) rises to unity for \( \partial V/\partial t > 0 \) and hence, by (7), \( \mu \) becomes infinite and, by (4), so does \( B_{gr} \). Equation (5) shows that for a fixed \( r \) and \( \lambda \), the ratio of \((\partial V/\partial t) / V^2\) to \( \Delta B_r \) depends on \( (VB_{gr}) \). For a positive/negative \( B_{gr} \), a given polarity of \( \partial V/\partial t \) will give the same/opposite polarity of \( \Delta B_r \) respectively. To remove the dependence on the polarity of \( B_{gr} \), we here... Figure 2. The distribution of predicted radial field difference (normalized to \( r = r_1 = 1 \text{AU} \)) \( c \times \Delta B_{t1} = c \times \{[B_r]_{t1} - (r_0/r_1)^2 [B_r]_0 \} \) between \( r_1 = 1 \text{AU} \) and the coronal source surface at \( r_0 = 2.5/251 \text{ AU} \). The shaded area is for \( c = 1 \) (and so includes the effect of the polarity of \( B_{gr} \)), and the black line is for \( c = |B_{gr}| \) (i.e., \( c = \pm 1 \)) which removes the effect of the polarity of \( B_{gr} \). The plot is for hourly data from the entire Omni-2 data set for 1963–2008. Figure 3. The distribution of predicted values at \( r = r_0 \) of the ratio \( (\partial V/\partial t) / V^2 \) (with \( V \) here expressed in units of AU s\(^{-1}\)). The \( \partial V \) values are interpolated from daily means to remove effects of fine structure in the variation in \( V \). The plot shows the hourly values from the entire Omni-2 data set for 1963–2008. Positive/negative values are for compression/rarefaction regions, respectively. use \( c = B_{\infty}/|B_{\infty}| = \pm 1 \). Figure 4 shows the distribution of values of \( c)[(\partial V/\partial t)/V^2]/\Delta B_r \) from the same data set as in Figures 2 and 3. The mode value of 0.02 applies to both compression and rarefaction regions. As in paper 1, we define the signed flux deficit for measurements made at \( r \) and \( r_1 \) to be \[ \Delta F_S(r) = 2\pi(|B_r|r^2 - |B_{r1}|r_1^2) \] The radial term of equation (2) gives \( B_r = (r_1/r)^2B_{ro} + \Delta B_r \) and \( B_{r1} = (r_1/r_1)^2B_{ro} + \Delta B_{r1} \). Substituting into (8), using equation (5) and rearranging gives the kinematic contribution to excess flux: \[ \Delta F_S(r) = 2\pi r_1^2 \Delta B_{r1} \left[ \frac{\mu (r - r_1) - 1}{\mu_1 (r_1 - r_0)} \right] \] All of the above equations assume that solar wind speed \( V \) does not depend on \( r \) but, as discussed above, when \( dV > 0 \) dynamical effects become important. This applies to the corotating interaction regions, as well as to temporal cases such as ahead of coronal mass ejections (CMEs). These dynamical effects are absent in rarefaction regions (\( dV < 0 \)) because the faster flow runs ahead of the slow flow. Hence it is instructive to repeat the distribution shown in grey in Figure 2 for values of \( c \Delta B_r \) for which \( c \) removes the effect of the polarity of \( B_{\infty} \): hence \( c \Delta B_r > 0 \) corresponds to \( dV > 0 \) (compression regions) and \( c \Delta B_r < 0 \) corresponds to \( dV < 0 \) (rarefaction regions). This is shown by the black line in Figure 2. It can be seen that the symmetric distribution for \( c = +1 \) has become slightly asymmetric with slightly lower numbers of samples giving large positive \( c \Delta B_r \) than give large negative \( c \Delta B_r \) of the same magnitude. This is consistent with the asymmetry expected for the dynamical stream–stream interaction effects which will be present in compression regions only. Thus we can conclude that using 1-day means to derive \( (dV/\partial t) \) has removed much, but not all, dynamical effects in the excess flux calculation. Because measurement uncertainties and our assumptions can sometimes (in <1% of hourly means) cause exceptionally large values of \( |\Delta B_r| \), we here exclude from the survey all samples which are more than 3\( \sigma \) from the mean (the standard deviation from Figure 2 being \( \sigma = 2.24 \) nT). Taking the integral of all the 87,759 available hourly positive \( c \Delta B_r \) values in Figure 2 up to this 3\( \sigma \) limit (i.e., in the compression regions) we get 0.33 Ts, whereas the corresponding integral value for all the 99,694 hourly negative \( c \Delta B_r \) values (i.e., in the rarefaction regions where \( dV < 0 \)) is \(-0.40 \) Ts. Because there are no stream–stream interaction effects in the rarefaction regions, and because the true integrated excess flux effect for \( dV > 0 \) regions should be equal and opposite to that for \( dV < 0 \); we can infer that the dynamical interactions have caused the procedure described above to underestimate the kinematic effect in compression regions by a factor 100(0.40–0.33)/0.40% = 17.5%, on average. Given the \( dV > 0 \) regions are present for 46.8% of the time, we can estimate that we may have underestimated the kinematic excess flux effect by some 0.468 \times 17.5 = 8.2%, on average. In theory, we could use Figure 2 to calibrate for this effect and remove the average residual dynamic interaction effects in compression regions: however, we do not attempt to implement such an average correction here and instead note the average level of **Figure 4.** The distribution of predicted values of the factor \( c)[(\partial V/\partial t)/V^2]/\Delta B_r \) (with \( V \) expressed in units of AU s\(^{-1}\)). The \( \partial V \) values are as used in Figure 3. The term \( c = B_{\infty}/|B_{\infty}| = \pm 1 \) removes the effect of the polarity of \( B_{\infty} \). The plot shows the hourly values from the entire Omni-2 data set for 1963–2008. The mode value is 0.2, and this distribution includes both compression (\( (\partial V/\partial t) > 0, \Delta B_r/c > 0 \)) and rarefaction (\( (\partial V/\partial t) < 0, \Delta B_r/c < 0 \)) regions. underestimation of the kinematic effect owing to dynamical effects in compression regions. 3. Kinematic Effects on Sampling The kinematic effects discussed in section 2 cause a bias in the sampling of the IMF/slow wind seen in the heliosphere [McComas et al., 1992]. Regions of \( \frac{\partial V}{\partial t_o} > 0 \) give \( dr < dt_o \), which means that a satellite at \( r > r_o \) will sample the resulting compression regions relatively more often than at the source region. Conversely regions of \( \frac{\partial V}{\partial t_o} < 0 \) give \( dr > dt_o \) and so fewer of the regular samples at the satellite will relate to these rarefaction regions, compared to at the source region. Hence if the field at the source surface is systematically different in the regions of \( \frac{\partial V}{\partial t_o} > 0 \) this would introduce a bias into the averages seen at \( r > r_o \). From equation (6) the value of \( dt_o \) corresponding to the sampling interval \( dr \) can be calculated for all the Omni-2 data from \( r = r_1 \), with the kinematic assumption that \( V \) is independent of \( r \). In addition to the conventional mean for a solar rotation, \( \langle |B_{11}| \rangle_{\text{CR}} \), we can compute a mean where each sample of \( |B_{11}| \) is weighted by a factor \( w = \left( \frac{dt_o}{dt} \right) / \left( \Sigma \frac{\partial |B_{11}|}{\partial t_o} \left| d_t \right| \right) \), which means it is weighted by the time interval relevant to at the source surface, rather than that at the point of observation. Figure 5 is a scatterplot of \( \langle |B_{11}| \rangle_{\text{CR}} \) and \( \langle w |B_{11}| \rangle_{\text{CR}} \) which shows there is no systematic difference between the two. Circles are averages for data in rarefaction regions (\( dV < 0 \)) whereas the triangles are for compression regions (\( dV > 0 \)). Individual solar rotations may show some deviation of \( \langle w |B_{11}| \rangle_{\text{CR}} \) from \( \langle |B_{11}| \rangle_{\text{CR}} \), and there is a slight tendency for the biggest deviations to be in compression regions. The scatter for this plot (which considers the difference between \( r_2 = (2.5/251) \)AU and \( r_1 = 1 \) AU) is somewhat greater than for the corresponding plot (Figure 5) in paper 1 for between \( r_1 = 1 \) AU and Ulysses at \( r_2 \approx 1.5 \) AU. We believe that this is partly because the range of \( r \) is greater and includes the solar wind acceleration region. However, on average, \( \langle w |B_{11}| \rangle_{\text{CR}} \) and \( \langle |B_{11}| \rangle_{\text{CR}} \) still agree very closely for both \( dV > 0 \) and \( dV < 0 \). As in paper 1, we can conclude that kinematic effects have not introduced a bias and this conclusion is not effected by dynamical effects in interaction regions (which are absent in rarefaction regions). Hence we can eliminate the kinematic bunching effect on sampling as a contributor to the flux excess. We have confirmed this conclusion using the theoretical model of kinematic structures developed by A. P. Rouillard and M. Lockwood (Solar stream magnetism: Analytic prediction of three-dimensional heliospheric fields and flows, submitted to Astronomy and Astrophysics, 2009). 4. Kinematic Effect on the Radial Field and Flux Excess Figure 2 shows the distribution of hourly \( \Delta B_r \) values computed using equation (6) for all the near-Earth \( (r \approx r_1 = 1 \) AU) observations between 1963 and 2008 in the Omni-2... data set. In order to evaluate the net effect over each solar rotation, we plot the equivalent distributions, an example being given in Figure 6 (top). As discussed in paper 1, it is valuable to use integer 27-day intervals and so we use Bartels rotation intervals rather than Carrington rotations (the former being 27 days the latter 27.2753 days). This particular example is for Bartels rotation number 2226. The number of hourly Omni-2 data points giving a predicted additional radial field of $|\Delta B_r|_k$ is $n_k$. The fraction of the total possible number ($N = 27 \times 24$) of hourly samples available for this particular solar rotation is $f = \Sigma n_k/N = 1.0$; that is, there are no data gaps in this case. (bottom) The ordinate is $[\Delta F_1]_{CR}/(N A_1)$, where $[\Delta F_1]_{CR}$ is the magnitude of the integrated additional radial field up to the limit $[\Delta B_r]$ (abscissa); i.e., $[\Delta F_1]_{CR} = \Sigma_{k=0}^N A_1 n_k|\Delta B_r|_k$, where $A_1$ is the area of the surface of the heliocentric sphere of radius $r_1$ that is swept out by unit length in the N direction (of the RTN coordinate system) by solar rotation during 1 h. The value at $[\Delta B_r]_i = -10$ nT is the predicted total of all detected inward extra flux $[\Delta F_1]_{in}$ and that at $[\Delta B_r]_i = +10$ nT is the corresponding integrated outward flux $[\Delta F_1]_{out}$. For stationary conditions over the solar rotation, with purely radial flow and no vestigial net effect of stream–stream interactions, we would expect $[\Delta F_1]_{in} = [\Delta F_1]_{out}$ and the mean additional radial field produced by kinematic effects would be $[\Delta B_r]_{CR} = 2[\Delta F_1]_{out}/(N A_1) = 2[\Delta F_1]_{in}/(N A_1)$. The dashed horizontal line shows the average of $[\Delta F_1]_{in}$ and $[\Delta F_1]_{out}$ which is here taken to be $(N A_1)/2$. Figure 6. (top) The same as Figure 2 but for a single Bartels rotation (in this example, number 2226). The fraction of the total possible number ($N = 27 \times 24$) of hourly samples available for this particular solar rotation is $f = \Sigma n_k/N = 1.0$; that is, there are no data gaps in this case. (bottom) The ordinate is $[\Delta F_1]_{CR}/(N A_1)$, where $[\Delta F_1]_{CR}$ is the magnitude of the integrated additional radial field up to the limit $[\Delta B_r]$ (abscissa); i.e., $[\Delta F_1]_{CR} = \Sigma_{k=0}^N A_1 n_k|\Delta B_r|_k$, where $A_1$ is the area of the surface of the heliocentric sphere of radius $r_1$ that is swept out by unit length in the N direction (of the RTN coordinate system) by solar rotation during 1 h. The value at $[\Delta B_r]_i = -10$ nT is the predicted total of all detected inward extra flux $[\Delta F_1]_{in}$ and that at $[\Delta B_r]_i = +10$ nT is the corresponding integrated outward flux $[\Delta F_1]_{out}$. For stationary conditions over the solar rotation, with purely radial flow and no vestigial net effect of stream–stream interactions, we would expect $[\Delta F_1]_{in} = [\Delta F_1]_{out}$ and the mean additional radial field produced by kinematic effects would be $[\Delta B_r]_{CR} = 2[\Delta F_1]_{out}/(N A_1) = 2[\Delta F_1]_{in}/(N A_1)$. The dashed horizontal line shows the average of $[\Delta F_1]_{in}$ and $[\Delta F_1]_{out}$ which is here taken to be $(N A_1)/2$. 7 of 14 Figure 7. The observed additional open flux $\Delta F_S$ as a function of $r/r_1$. The colored dots are the differences between full solar rotation averages observations from various spacecraft, compared with the coincident Omni-2 data value. The lines are from the predicted $|\Delta B_{1|CR}|$ from the Omni-2 data using the mode value of the distribution shown in Figure 3 (see text). The lines show the $\Delta F_S$ values which would be exceeded a fraction $p$ of the time where $p$ is 0.1 (for black line), 0.25, 0.5, 0.75 and 0.9 (light gray line). of all predicted inward extra flux $[\Delta F_1]_{in}$ during the solar rotation in question and that at $[\Delta B_{1|}] = +10$ nT is the corresponding integrated outward extra flux $[\Delta F_1]_{out}$. In this case $[\Delta F_1]_{in}$ is slightly smaller than $[\Delta F_1]_{out}$ for some other solar rotations it is the other way round and only relatively rarely are the two exactly equal. For stationary conditions over the solar rotation, with purely radial flow and no residual contributions of dynamic effects in compression regions, we would expect $[\Delta F_1]_{in} = [\Delta F_1]_{out}$ and the mean additional radial field produced by kinematic effects would then be $[\Delta B_{1|CR}] = 2[\Delta F_1]_{in}/(N_{A1}) = 2[\Delta F_1]_{out}/(N_{A1})$, the factor of 2 arising because both the inward and outward flux contribute to the absolute value of the radial field. We attribute the differences between $[\Delta F_1]_{in}$ and $[\Delta F_1]_{out}$ detected to either nonstationary conditions over the solar rotation, to residual dynamical effects, to data gaps and/or to nonradial flow. We here take the arithmetic mean of $[\Delta F_1]_{in}$ and $[\Delta F_1]_{out}$ (the dashed horizontal line in Figure 6 (bottom)) to be equal to $(N_{A1}) [\Delta B_{1|CR}]/2$. Using this estimate of $[\Delta B_{1|CR}]$ will introduce some scatter into the values for individual solar rotations, but which should average out when sufficient solar rotations are considered together (e.g., in annual means). [18] Figure 7 shows solar rotation averages of the observed flux excess $\Delta F_S$, computed as a function of $r$ using equation (8), from a survey of data from a number of spacecraft throughout the heliosphere. This is an updated version of Owens et al. [2008a, Figure 1]. Points are colored according to the spacecraft giving the observations away from 1 AU, as given by the key. The simultaneous data from 1 AU is taken from the Omni-2 data set. It can be seen the excess flux increases with $r$ as does the scatter about the trend. [19] The lines in Figure 7 are predicted using the theory given in section 2 in the following manner. The values of $|\Delta B_{1|CR}$ for each solar rotation are computed (as demonstrated by Figure 6) and from the distribution of these solar rotation values are taken the upper and lower deciles, the upper and lower quartiles and the median (i.e., the probability of $|\Delta B_{1|CR}$ exceeding these values is $p$ equal to 0.9, 0.1, 0.75, 0.25 and 0.5). These five values are then used to generate the corresponding $|\partial V/\partial \phi|/V^2$ values using the mode value of the distribution shown in Figure 4 (which is $m = 0.2$ AU$^{-1}$ nT$^{-1}$). These are then used to generate a pair of $\mu(r)$ profiles for each of the 5 $p$ values using equation (7) with $|\partial V/\partial \phi|/V^2 = \pm m |\Delta B_{1|CR}$ (the plus being for compression regions, the minus being for rarefaction regions). These are then averaged together and the average $\mu(r)$ profile is then used with equation (9) to extrapolate each of the above five values to other $r$. Extrapolation has been curtailed at the point where the compression regions are tending toward giving infinite field as this is where the kinematic disturbance would steepen into a shock [Burlaga et al., 1983]. [20] Thus we can predict the flux excess $\Delta F_S$ that we would expect at a given $r$ to be exceeded with a probability $p$ of 0.1, 0.25, 0.5, 0.75 and 0.9 of the time. These are the five lines in Figure 7 (shaded from black to light gray). It can be seen that these fit the observations reasonably well and shows that the flux excess is indeed consistent with the kinematic effects described in section 2. The spread of the Figure 8. (top) The additional open flux $\Delta F_S$ as a function of $r/r_1$, where $r$ is the heliocentric distance and $r_1 = 1$ AU. The data points show the mean values from the spacecraft data shown in Figure 7, averaged over $r$ bins 0.1 AU wide, with error bars of plus and minus one standard deviation. The lines are the same as shown in Figure 7. The data point at the lowest $r/r_1$ is the entire PFSS data set for the coronal source surface at $r = r_o$. (bottom) The number of full solar rotation averages $n$ contributing to the means. The open triangle shows the number in the Omni-2 data set from $r = r_1$. Note that $n$ is shown on a logarithmic scale. Figure 9. The gray shaded areas show annual means of the signed open solar flux from the Omni-2 data $[F_S]_T = 2\pi r_1^2 \langle |B_r|_T \rangle$, with absolute values taken of means on timescale $T$. The light gray area bounded by the blue line is for $T = 1$ h ($[F_S]_T = 1hr$) and successively darker gray areas are for $T = 1$, 2, and 3 days. The green line is the corresponding value from the PFSS data, mapped to $r = r_1$, with no allowance for kinematic effects, $[F_S]_{PFSS}$. The red line shows the Omni-2 values for $T = 1$ h, minus the correction term for kinematic effects, $[F_S]_C = 2\pi r_1^2 \langle |B_r|_{T=1hr} - \langle \Delta B_r \rangle_{CR} \rangle$. $[F_S]_C = 2\pi r_1^2 \langle |B_r|_{T=1hr} - \langle \Delta B_r \rangle_{CR} \rangle$. $[F_S] = 2\pi r_1^2 \langle |B_r|_T \rangle$. lines for different $p$ matches the observed scatter reasonably well. Figure 8 shows the data from Figure 7 for $r < 5$ AU. Instead of individual solar rotation values of $\Delta F_S$, means for bins of $r$ that are 0.1 AU wide are shown with error bars of plus and minus one standard deviation. Figure 8 (bottom) shows the number of solar rotation averages in each bin (on a logarithmic scale). The five lines are the same as in Figure 7. By definition of $\Delta F_S$, all five lines pass through zero at $r = 1$ AU. In addition to the satellite data from Figure 7, the mean and standard deviation of all PFSS values are shown by the leftmost data point in Figure 8. It can be seen that the flux excesses for these PFSS estimates lie on the same trend with $r$ as do the satellite data (and are negative; i.e., the PFSS values are lower than those from $r = 1$ AU). We therefore infer that the tendency for lower PFSS values noted by Wang and Sheeley [1995] and Lockwood et al. [2006] has the same origin as those noted in spacecraft data by Owens et al. [2008a] and both are consistent with kinematic effects introduced by large-scale spatial velocity gradients. 5. Long-Term Variations in Open Solar Flux Figure 9 shows annual means of the open flux derived for averaging timescales $T$ of 1 h, 1 day, 2 days and 3 days (gray shaded areas). The red line shows the variation for $T = 1$ h, minus the kinematic correction $|\Delta B_r|_{CR}$ derived as described above, $[F_S]_{CR} = 2\pi r_1^2 \{[B_r]_{T = 1 h} - \langle B_r \rangle_{CR} - \langle \Delta B_r \rangle_{CR}\}$. Note that because this correction uses the observed tangential field value $B_{r1}$ at $r = r_1$ with equation (5), it does not rely on the average procedure used to obtain $\mu(r)$ and hence generate the $\Delta F_S(r)$ profiles in Figures 7 and 8. The green line shows the values derived from magnetograph data using the PFSS method [Wang and Sheeley, 1995]. $[F_S]_{PFSS}$. Additional data gaps appear early in the corrected data sequence (in red) because we require both IMF and solar wind data and we set a requirement 50% data availability. It can be seen that the corrected open flux values match the PFSS data rather well, better than those obtained using $T$ of 1–3 days. The r.m.s. difference between the PFSS values and the kinematically corrected open flux values is $4.1 \times 10^{13}$ Wb, whereas the corresponding r.m.s. difference for using averaging over $T = 1$ day is $6.9 \times 10^{13}$ Wb. Thus the kinematic correction performs better on average but not dramatically so. Last, Figure 10 shows the variation of solar rotation averages (thin dark gray line) and annual means (thick black line) of the open solar flux, corrected for the kinematic effects, as described above. The most notable feature is how rapid the descent of open solar flux has been over recent cycles. The annual mean open flux for 1987 is a solar minimum value of $0.382 \times 10^{15}$ Wb, whereas the annual mean open flux in 2007, also a solar minimum value, is $0.198 \times 10^{15}$ Wb. In other words, the annual mean open solar flux was 93% higher in 1987 than it was in 2007. 6. Discussion and Conclusions The analysis presented here has shown that the flux excess seen by various spacecraft in the inner heliosphere (mainly close to the ecliptic plane) is consistent with the difference between values derived using in situ data from heliocentric distances of $r \approx 1$ AU compared to those deduced from solar magnetograph data using the PFSS method. In addition, we have shown both are consistent with kinematic effects in the streamer belt owing to large-scale (timescales $T > 1$ day) longitudinal structure in the solar wind flow. [25] There is no kinematic effect unless there is a tangential seed field in the region of high solar wind speed shear. The origin of such tangential seed fields could be, for example, near-Sun interchange reconnection of magnetic field or could be faster flow emerging beneath overdraped Parker spiral field (temporal effects such as CMEs). Because the analysis starts from the observed field at $r$ near 1 AU and maps back to the source surface ($r = r_o$), our results do not depend on the mechanism which generates the tangential seed field in the first instance. We have investigated the effect of the biggest assumption made (that $V$ does not depend on $r$, i.e., assuming that dynamical stream–stream interaction effects have been largely removed by the 1-day smoothing time constant applied to the observed velocity gradient) and found that the resulting difference between compression and rarefaction regions is small. We conclude the vestigial effects of stream–stream interactions in our kinematic correction terms are small and tend to cancel out. [26] Figure 9 shows that the temporal variation of the annual mean of the corrected open flux $[F_{SC}]_T$, derived by applying the kinematic correction for excess flux to whole-solar rotation data from spacecraft near 1 AU, matches very well that from PFSS modeling on the basis of magnetograph data. In particular, the two agree somewhat better than applying by preaveraging over a fixed interval $T$. Up until about 1986 (solar cycles 20 and 21), using $T = 1$ day ($[F_{SC}]_{T = 1 \text{ day}}$) matches the PFSS data rather well; however, over cycle 22 $[F_{SC}]_{T = 2 \text{ day}}$ matches better and over cycle 23 even $[F_{SC}]_{T = 3 \text{ day}}$ does not give an adequate correction. As discussed in the introduction, there will, at any one time, be a $T$ value for which the derived open flux at 1 AU equals the correct value at the source surface; however, Figure 9 implies that the optimum $T$ at 1 AU has changed. The agreement with PFSS open flux estimates is improved somewhat if we use the kinematic correction rather than averaging over intervals of $T = 1$ day (the r.m.s. deviation is reduced by about a third). [27] Paper 1 showed that small-scale structure (timescales less than 1 h) does not contribute to flux excess, but structure on timescales between 1 h and 1 day could still be a factor: the use of means over, for example, $T = 1$ day would be the best way to remove such structure. Because of dynamical interactions, our analysis of kinematic effects needs to smooth the observed velocity gradients (we use a time constant of 1 day) and so we here have predicted the kinematic effects of flow structure on timescales of $>$1 day. These can match the observed flux excess, and its variations with $r$ and time, rather well. However, we cannot eliminate the possibility that there is a contribution to the excess flux from structure on timescales between 1 h and 1 day (at least some of which could come from dynamical effects). In this discussion about the physical origin of the flux excess, it is interesting to note the latitudinal difference reported in paper 1: that the flux excess was considerably greater in the streamer belt than outside it. Lockwood and Owens [2009] show that, in fact, this only applies around sunspot minimum and that near sunspot maximum the flux excess is roughly as great at high heliographic latitudes as at low latitudes. This clearly points to kinematic and/or dynamical interaction effects as the physical origin of the flux excess. Naturally, in general, one cannot have one without the other. However, here we have used smoothing to damp the dynamical effects (and shown that this is approximately achieved because rarefaction and compression show similar results) and find a close agreement of the data with the kinematic effects predicted for the background solar wind flow structure on timescales of $>$1 day. However, this does not eliminate contributions to the excess flux of structure in the field from another source on timescales in the range 1 h to 1 day. [28] Figure 9 shows that the open solar flux in the current solar minimum is lower than at any previous time since measurements of interplanetary space began in 1963, and that rapid descent has occurred since the maximum of the long-term variation in open solar flux in 1987 identified by Lockwood [2001, 2003] and Lockwood and Fröhlich [2007]. Here we note, the correction $2\pi r^2|\Delta B_r|_{\text{CR}}$ (needed to match PFSS values) has increased slightly in magnitude. Note that the low values of open fluxes for the current solar minimum do not only originate from data from the ACE and WIND spacecraft (which are the major contributors to the Omni-2 data at this time): Paper 1 shows that they are consistent with the Ulysses data at larger $r$ and Owens et al. [2008a] have shown that values from the two STEREO craft, at similar $r$ but different solar longitude $\varphi$, are almost identical. [29] A number of models for the evolution of the heliospheric magnetic field have been proposed. Fisk et al. [1999] argue that the Sun’s open flux tends to be conserved, with “interchange reconnection” [see Crooker et al., 2002] between open and closed solar fields resulting in an effective diffusion of open flux across the solar surface without, necessarily, any net change in the total open flux. In this case, the heliospheric field evolves with simple rotation of regions of positive and negative polarity separated by a single, large-scale heliospheric current sheet [Fisk and Schwadron, 2001; Jones et al., 2003]. Alternatively, it has been argued that emerging midlatitude bipoles cause closed coronal loops to rise and first destroy preexisting open flux in the solar coronal hole (remnant from the previous solar cycle) and then build up a new polar coronal hole (of the opposite polarity) and so reverse the polar field of the Sun [Babcock, 1961; Wang and Sheeley, 2003], which fits well with the migration of photospheric fields inferred from magnetograph data. The evolution of the heliospheric magnetic field could also be facilitated by transient events [Low, 2001]: specifically, Owens et al. [2007] and Owens and Crooker [2006, 2007] investigate the role of the magnetic flux contained in coronal mass ejections (CMEs) in the observed variation in flux seen by craft in the heliosphere. These different concepts are not mutually exclusive in many respects (see review by Lockwood [2004]). [30] Much of the difference between these concepts is a matter of semantics. “Open flux” has here, and in many previous papers, been taken to be the same as “coronal source flux;” that is, the magnetic flux that leaves the solar atmosphere and enters the heliosphere by threading the coronal source surface at 2.5 solar radii. It is a readily measurable quantity because of PFSS modeling (within the assumptions of that technique) and because the Ulysses result allows the use of in situ magnetic field data (but we have shown that some form of correction is needed for the excess flux effect). This is quite different from another definition of open flux which requires that it has only one foot point still attached to the Sun [e.g., Schwadron et al., 2008]. Flux which appears to be in this category can sometimes be inferred for in situ point measurements, for example from heat flux or unidirectional “strahl” electron distribution functions, although scattering by heliospheric structure into other populations such as “halo” often makes this far from unambiguous [Larson et al., 1997; Fitzenreiter et al., 1998; Owens et al., 2008c]. Even if this could be done reliably, there is no way to quantify the total of such flux at any one time from such in situ point measurements. This is because there is no equivalent of the Ulysses result (and so no equivalent to equation (1) for this flux) to generalize in situ point measurements into a global quantity. To make the distinction clear, let us here refer to these two definitions as the “total open flux” $F_O$ (defined by equation (1)) and the “single–foot point open flux” $F_O$. The latter is a subset of the former. The only topological distinction that $F_O$ can have which separates it from other heliospheric flux (the $F_S - F_O$ of double–foot open flux) is that it threads the heliopause and enters interstellar space. (Note that any other definition involving any boundary within the heliosphere will cause the continuous conversion of the flux ($F_S - F_O$) into $F_O$ as the magnetic flux frozen-in to the solar wind flow propagates through that boundary). [31] Until we can quantify $F_O$, there can be no evidence that it is constant and thus the idea that it is constant can be no more than a hypothesis. Confusingly, it has been claimed that the total open flux $F_S$ is constant and that this is evidence that the single–foot point open flux $F_O$ is constant. The key point we wish to underline here is that $F_S$ is far from constant. [32] Coronal mass ejections are an important example (but not the only example) of flux that undoubtedly contributes to $F_S$ but may not contribute to $F_O$ [Mackay and van Ballegooijen, 2006]. Consider a magnetic flux tube which is an element of a CME and which contains a magnetic flux $F_E$. It will enhance the flux $F_S$ by $2F_E$ ($F_E$ at each foot point), once it has propagated beyond the coronal source surface without any foot point disconnection. This emergence does not change $F_O$. However, unless $F_S$ is to increase indefinitely with continuing CME emergence, other processes must occur. Emergence followed by subsequent reconnection with a preexisting similar loop (i.e., with dual–foot point open flux which is part of $F_S$ but not part of $F_O$) will give no net change in either $F_S$ or $F_O$. Emergence with subsequent disconnection in one hemisphere A by magnetic reconnection with preexisting single–foot point open field (residual from the previous solar cycle and thus with the opposite polarity) will also give no net change in either $F_S$ nor $F_O$ (Note that single–foot point flux of the old polarity attached to hemisphere A has decreased by $F_E$ whereas the new polarity flux attached to hemisphere B has increased by the same amount; i.e., this is foot point exchange). If reconnection of CME flux with single–foot point open flux can occur in hemisphere A, there is no reason why sometimes it cannot also occur in the other hemisphere B (either simultaneously or, more likely, sometime before/after). Emergence followed by complete foot point disconnection (in both hemispheres) causes both $F_S$ and $F_O$ to fall by $2F_E$. The CME processes therefore acts to either conserve or decrease $F_O$. If $F_O$ is decreased, the counterbalancing source would be reconnection at the heliopause of dual–foot point open flux ($F_S - F_O$) with the magnetic field in interstellar space (which increases $F_O$ but does not alter $F_S$). This would be, at most, only distantly related to the near-Sun processes. [33] The time series of the total open flux $F_S$ shown in this paper (Figure 10) and by prior publications reveals that there is considerable variation. The total open solar flux at solar minimum fell from an annual mean of 3.82 x $10^{16}$ Wb in 1987 to close to half that value (1.98 x $10^{16}$ Wb) in 2008. [34] Long-term variations in the total open solar flux $F_S$ have previously been inferred from historic geomagnetic data by Lockwood et al. [1999a, 1999b], Lockwood [2001, 2003] and Rouillard et al. [2007], showing that the open solar flux roughly doubled between 1900 and about 1950. It has been claimed that this rise was an artifact of the aa geomagnetic data [Svalgaard et al., 2003, 2004] or was present but much smaller in magnitude [Svalgaard and Cliver, 2007]. Analysis using a wide variety geomagnetic data show neither to be the case [e.g., Rouillard et al., 2007]. In this debate, the important difference between open solar flux $F_S$ (and hence by equation 1 the radial field component) and the heliospheric field strength $B$ has also often been overlooked. As a result, discussion of the existence [Svalgaard and Cliver, 2005], or otherwise [Owens et al., 2008b], of a “floor” minimum to $B$ is irrelevant. Rouillard et al. [2007] pointed out the role of even uniform solar wind flow speed $V$ in decoupling $F_S$ and $B$. (In Parker spiral theory, increased/decreased $V$ causes the spiral to unwind/wind up and so $B$ falls/rises for a fixed $F_S$). But these authors point out this is not the only effect which in the past has been accounted for using the timescale $T$ [Rouillard et al., 2007; Lockwood et al., 2006]. In the present paper, we have shown that this additional effect is consistent with longitudinal structure in the solar wind flow which gives the kinematic flux excess effect. [35] The long-term change in the open flux deduced from geomagnetic activity has been reproduced by a number of numerical models of flux continuity and transport during the solar magnetic cycle, given the variation in photospheric emergence rate indicated by sunspot numbers [Solanki et al., 2000, 2002; Schrijver et al., 2002; Lean et al., 2002; Wang and Sheeley, 2003; Wang et al., 2005]. The principle laid down by Solanki et al. [2000, 2002] is that total open flux $F_S$ obeys a continuity equation, with the rate of change of $F_S$ being the difference between a source term (the total rate that coronal field loops emerge through the coronal source surface, including CMEs and loss terms owing to field reconfiguration and disconnection by magnetic reconnection). The discussion above about CME effects illustrates that several different topologies of disconnection must be active (see review by Lockwood [2004]). In the absence of known mechanisms that could make the total loss (from the variety of mechanisms) exactly equal to the simultaneous production rate, we must expect the total open flux to vary on a variety of timescales. [36] In this context, it is worth noting that the annual mean solar minimum open solar flux, derived here with correction for kinematic effects, was almost twice as large in 1987 than it was in 2007. This means that the observed fall in the minimum value over the last two solar cycles was considerably faster than the rise inferred from geomagnetic activity observations over four solar cycles in the first 20th century. [37] Acknowledgments. All three authors are supported by the UK Science and Technology Facilities Council. We are also grateful to the Space Physics Data Facility and the National Space Science Data Center for provision of the Omni-2 data set and to many scientists who contributed to both Omni-2 and to other magnetic field observations used here: from Pioneer 6 and 7 (principal investigator N. Ness), Pioneer 10 and 11 (principal investigator E. Smith), Pioneer Venus Orbiter (principal investigator C. Russell), Helios (principal investigator N. Ness), Voyager (principal investigator L. Burlaga), ICE-ISEE3 (principal investigator E. Smith), Ulysses (principal investigator A. Balogh), and STEREO (principal investigator M. Acuna). We also thank Yi-Ming Wang for the provision of the PFSS data. [38] Amitava Bhattacharjee thanks the reviewers for their assistance in evaluating this paper. References Svalgaard, L., E. W. Cliver, and P. Le Sager (2003), No doubling of the Sun’s coronal magnetic field during the last 100 years, *Geophys. Res. Abstr.*, 5, 07616. (Available at http://www.cosis.net/abstracts/EAE03/07616/EAE03-L-07616.pdf) M. Lockwood and A. P. Rouillard, Space Environment Physics, School of Physics and Astronomy, Southampton University, Southampton SO17 1BJ, UK. (m.lockwood@rl.ac.uk) M. Owens, Space and Atmospheric Physics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ, UK.
Summary It’s Aaron’s first mission for SHIELD since he and Marta joined them about six weeks ago. It has been four weeks since the brothers first met. What will happen if the mission goes sideways? Notes Disclaimer: I own nothing but the story, though I would like to appreciate a Clint or Aaron of my own, thank you! I also own this ‘verse, Author's notes: Lots of love to my betas: anuna_81 for providing lots of thinky thoughts on the characters and making sure they were recognizable, cheering me on all the way :) And hufflepuffsneak for your keen eyes, making sure that it reads right and for being super encouraging :) Thanks a mill again, my dears, I couldn’t have done it without you! Aaron ran, zigzagging, rabbiting from the HYDRA compound with the goons chasing him. He wouldn’t have worried, if it hadn’t been for the AK-47’s they were brandishing. "Uhm guys, I could use a little help here," he panted as he ducked to provide less of a target. The HYDRA cell they were investigating was manufacturing some kind of super anthrax. All they had needed was a sample of the bacteria for analysis to ensure the safety of everyone involved. Aaron had been the logical choice, a genetically enhanced solo operative, and he had relished the chance to prove himself in the field. The infiltration had gone smoothly; Aaron had just informed Clint that he had obtained a vial of the bacteria. And then it all went to hell in a hand basket in a matter of moments. “What happened?” Clint asked, his voice calm and steady. Aaron would have sighed in relief if he’d had the breath to spare. Clint. Just the guy he needed. “I got made, now a dozen goons with guns are after me,” he breathed. “I can’t get up high, can’t shake ‘em.” “I see you,” Clint said. “I need an exit,” Aaron panted, assessing the terrain in front of him. There was hardly any cover, the old plant the HYDRA cell had set up shop in was the only building around. He headed towards a line of trees that just might provide sufficient cover for a little while, but he had no idea how dense the trees were. “The trees won’t help you much; cover’s not deep enough to lose them. Go straight through and then head right, there’s a deserted village. No roof access, most of them have caved in. But you might be able to shake ‘em in the streets,” Clint instructed. Aaron was running for his life, breaching the tree line, when it happened. A shot found its mark, searing pain in his right shoulder tearing through him, his body jerking forward from the bullet’s momentum as it hit. “Aaron,” Clint yelled into the comms, Aaron could make out a slight tremor in his voice. Aaron stumbled, then caught himself on a tree and slipped between the light cover of the trees. Fuck, it hurt. The bullet was lodged in his shoulder blade, he could feel it. But he grit his teeth and hurried on despite the pain, he was never gonna make it out if he stayed still. “Envelope is secure,” he panted, referring to the sample of the toxin he had been able to stow away in a padded pouch inside his jacket before his cover had been blown. “And you?” Clint demanded. “I’ll live,” Aaron replied, dumbfounded at the unexpected concern for him coming through the comm. “Just get me somewhere they can’t follow.” “Alright. Head right, those houses look abandoned, you should be able to take cover somewhere. I’m coming to get you, alright? You hear me? I’m coming.” Aaron would have laughed with relief if he’d had the strength, he knew Clint wouldn’t leave him hanging. It felt good to have backup that genuinely cared about him, he’d never had that before. “Okay,” he replied wearily, the wound in his shoulder sapping his energy. “You should make it to the structures before they clear the trees if you can keep up the pace,” Clint instructed. Aaron rallied, grunting in pain as he straightened up and ran full tilt. If he could only make it to the first house, he could hole up there if need be, hide somewhere. “I hear engines ahead, coming closer,” Aaron huffed as he neared the entrance to the first building. He startled as Natasha’s calm voice filled the comm, saying, “That’s our guys. SHIELD forces are on their way. We’re gonna get you out before you get caught in the crossfire between HYDRA and us.” “That’d be nice,” he replied, breaching the door to the first ramshackle building just as bullets started flying around him. He breathed a sigh of relief as he entered the cover of the abandoned house. The wooden floors were littered with debris that impeded his long strides and he swore at it under his breath. The breath was startled out of him as his foot crashed through the floor on his next step. A loud rumbling started around him and he pitched forward as his momentum carried him on. The floor below him gave way and he tried to turn as he fell, hoping to break his fall with his back. The vial that held the toxin could not be damaged. He crashed into the cement floor of the cellar, his right side erupting with pain, his vision whitening out. His ears rang as something hurled towards him. Then the world went black around him. Marta stared at the monitor, watching the building collapse. Her knees went weak and her fingernails dug into Clint’s arm. He didn’t seem to notice. His voice didn’t change at all as he kept repeating Aaron’s name, trying to get a reaction, yet the comm stayed silent. How could he stay so calm when Marta found it hard to breathe as the words no, and Aaron kept playing in an endless loop in her head? Natasha saying, “The team is ready, we’re leaving now,” shook her from her fixation with the monitor’s image and she whipped around. She had to go with them; she had to be with Aaron. He had saved her life over and over while they were on the run, she couldn’t leave him alone now. Reining in her emotions she squared her shoulders and caught onto Clint’s wrist, saying “I’m coming with you.” Only now did she notice the way his hands were balled into tight fists and she suddenly understood what it must cost him to keep his professionalism in this situation. His eyes found hers and for a second she thought he could read her every thought. Then he nodded and both joined the rest of Strike Team Delta as they hurried to the waiting quinjet. Natasha handed her a comm link as they took off, saying “It’s set to Aaron’s frequency. You will stay with Clint at all times when we touch down, understood?” She nodded, taking the tiny piece of plastic and inserting it into her ear. “Aaron?” she called lowly, hoping to hear something. Static. She looked to Clint, he shook his head. Her stomach knotted in dread. Please don’t be dead, please be alright, please. “Please, Aaron,” she said aloud, her hands fisting in the hem of her shirt. But the comm stayed silent. She saw Clint switch off his comm and turn to talk to Natasha. They were going over their strategy, no doubt. It didn’t concern her, she was no tactician, spy or soldier, she was only here for one reason. Aaron. “Aaron? Come on Aaron, don’t do this, dammit. I know you’re there, come on Aaron.” There was only silence. “Touchdown in five,” the pilot announced over the comms. She watched as Clint assembled his sniper rifle and the rest of the team, six men and two women including Natasha, checked their tac vests and weapons. Her heart plummeted as she realized that she was really entering a battle zone. She knew how to use a gun, but her close quarters combat skills were rudimentary. Aaron had taught her how to defend herself, but she’d never had to use any of the moves he’d shown her. Just then she saw Clint and Natasha’s hands clasp briefly as they looked into each other’s eyes for a second, the moment gone as fast as it had come. And not for the first time did she wonder if they ever let down their guards completely, allowed themselves a respite from their professional wariness. She didn’t have time to really dwell on that thought as Clint approached her with a tac vest and helped her put it on. Aaron, I’m doing this for Aaron, she thought as her heart thumped wildly. “Has he responded yet?” he asked her. She shook her head no and saw his face turn stony for a fraction of a second. He shook it off, saying, “You’ll stay with me. I’ll take out the HYDRA soldiers so our guys can get to Aaron. I won’t be able to talk to him when you rouse him, so you’ll keep him awake and talking, okay? We’ll get him out of there. I promise.” When, not If, the conviction in his voice made shivers run down Marta’s spine. She didn’t doubt him for a second. Marta nodded, that was what she’d wanted, be close, make sure Aaron made it out okay. Clint briefly clasped her shoulder and prepared for the landing. “That brother of yours is quite impressive,” she told Aaron. He couldn’t hear her, but she could imagine him agreeing with her assessment. The hold opened and the team dispersed, Clint and Marta hurrying to the spot on the hill Clint had decided on as his sniper’s nest, while Natasha took the rest of the team to the plant. Marta could hear machine-gun fire and found herself transported back to her house, cowering in the corner as shots rang out. She’d hoped to never find herself in a situation like that again. But Aaron had called her a warrior and it felt like a curse in retrospect, she couldn’t stay behind, not when she could go and be with him, try to be there for him. She swallowed her fear, took a deep breath and followed Clint. For Aaron, she could do it for Aaron. They made it to their spot without incident and Clint set up his rifle. Marta flinched when the first round left Clint’s barrel and he called out, “One down,” a few seconds later. Marta tried to tune out the sounds, concentrating on Aaron. “Aaron, we’re here, please talk to me. Come on, don’t do this to me. Aaron, dammit.” And there, almost undetectable over the sounds of the battle was a break in the static. “Aaron,” she called again, holding her breath, straining to hear something, a breath, a word, anything. And there it was - a moan, a sharp intake of air, and then a cough. “Aaron,” she released her pent up breath, smiling. “I’m here,” came his soft reply. He was alive. Talking. “Are you okay?” she asked tentatively. “Not really,” he panted. Of course he wasn’t okay. “I’m here, Aaron. Hang in there, please,” Marta pleaded. “Not going anywhere,” Aaron ground out and a fierce smile raced across her features. Then he spoke again, his voice full of concern, “It’s dangerous, you shouldn’t be here.” “Did you forget? You told me yourself that I am a warrior. I’m always gonna come for you.” She flinched as another shot rang out beside her. “Not worth it,” he breathed out and she felt frustration flood her. “Two down,” Clint called out beside her, then demanded, “He’s awake? How is he? Ask him for a sit rep. And how he’s doing. And what he remembers from the plant.” She turned to him, her fear for Aaron unloading onto Clint with a snarled, “Yes, he is. I can handle it. Go back to shooting people so we can get him out of there, okay?” She was sorry the second the words had left her mouth, he was only here to help and out of concern for his brother. His eyebrows rose, but he stopped butting in and concentrated on his mission again. Turning her attention back to Aaron she said, “Now, tell me what happened.” She could hear him release a breath, then say, calmer than before, “Uhm, fell through the floor, landed on my back, don’t remember much past the impact.” “Are you hurt, can you tell me what’s wrong?” There was a short pause and then a harsh intake of breath, before Aaron’s voice filled the comm again. “My right arm’s broken. An’ something’s wrong with my right leg. Doesn’t feel broken, but it hurts.” “And the gunshot wound?” she asked, trying to keep her voice even. She couldn’t, she wouldn’t fall apart now. That was not what she had come here for. “Still bleeding, hit my shoulder blade, think the bullet’s still in. Breathing hurts,” he said, his voice expressionless, the way she had come to learn meant he was hiding something. “So, let me recap this for your brother. You’re bleeding from the gunshot wound, the bullet is still in. Your arm is broken and something’s wrong with your leg but you don’t think it’s broken.” Marta bit her lip to keep from letting her emotions show. She looked at Clint, his face set in a grim mask, his posture rigid. She could practically see the calculations running through his head, assessing the situation, determining how to best help his brother. “Sounds about right,” Aaron replied and Marta could hear an edge of panic in his voice. “What’s wrong?” she asked as another shot from Clint had her hold her breath, wishing she was anywhere but here, that she and Aaron were on a tropical island somewhere. “I,” he took a shuddering breath, “can’t feel my arm anymore. Fell asleep. Can’t move. Can’t, there’s no space. Marta, there’s no space to move.” She could hear him start to hyperventilate. Helpless, he was probably feeling helpless, the most difficult thing for him to take. But she couldn’t let him panic, not while she couldn’t get to him. She inhaled deeply, forcing her reeling emotions down. For Aaron, she thought, I can do it. Calmly she said, “Aaron. Aaron, it’s okay, you’ll be fine. We’re almost done here. We’re almost there, we’ll come find you.” Clint loosed another shot and a second and third immediately after. “Affirmative,” Clint said, “Only two left.” Marta turned all her concentration towards Aaron. His breathing was fast and labored, and she was scared for him. She had to keep him from panicking, so she swallowed her fear and started talking. “Aaron, close your eyes. Remember our time on the boat? In the Chinese Sea? The water was so unbelievably clear. And I said that I wished we were lost. Do you remember that? Can you picture the sea?” “Yes, I remember,” he said, his breathing still ragged, “that was when I thought I might have a chance with you yet.” “I was so scared, but you always kept me safe. You made me stronger than I ever thought I could be.” She could hear his breathing evening out and released a sigh of relief. “That was when I first admitted to myself that there is something between us and I just wished for more time.” “Yeah, me too. ‘m glad we got the time,” he slurred, and Marta’s stomach turned into a chunk of ice. Two more shots rang out behind her, making her flinch and stop talking. She turned to Clint who was lowering his rifle, his brow furrowed in concentration as he listened to his comm. Then he nodded, saying, “Roger that,” and turned to her. “Let’s go,” was all he said as he got up, helped her stand and started down the incline. “We’re coming Aaron. We’re coming now.” “Good,” he said, sounding weary. “I can hear the guys pulling away boards. Feel it too.” “Yes, there’s a lot of them, and we’re doing our best to get to you. Just keep your eyes closed and think of the sea. The breeze felt so good against my skin. I knew being there with you that I was safe. You’re my safe haven, Aaron. I love you.” Aaron replied with a murmured, “Love you too.” Then he keened and fell silent. Marta felt like someone had punched her in the gut, all air driven Making the kills had been harder than Clint had anticipated, concentrating almost impossible. His comm had been set to his team’s frequency, their part of the op going down without a hitch. He hadn’t worried about Nat and the others at all; the op was a cakewalk. Get in, secure the hazardous material, apprehend enemy personnel, blow the place up. Easy as pie. Having a sample of the bacteria beforehand would have been preferable, but it couldn’t be helped. As long as the toxin wasn’t released while his team was in the disused factory everything would be okay. He heard Natasha confirm their taking of the enemy compound at the same time the last enemy combatant fell, Clint’s bullet tearing through his chest. He felt an odd sense of satisfaction. He didn’t particularly enjoy killing, but he was willing to make an exception in this case. He had kept an ear on Marta, following her side of the conversation with Aaron. And what he heard made his stomach clench in apprehension. Aaron wasn’t doing well. His little brother. He hadn’t been able to protect him. The thought didn’t sit well with him. As soon as command confirmed the last kill he slung his rifle over his shoulder, only one thought on his mind. He had to get to his brother. He helped Marta up and hurried to the collapsed building Aaron was trapped beneath. Men and women in SHIELD uniforms were already pulling debris aside when they made it to the bottom of the incline. Then he heard Marta calling “Aaron? Aaron?!” and his heart plummeted. He turned to her and his hand clamped around her arm. “What happened?” he demanded as his heart pounded in his chest. “He just – he keened and now he’s not responding,” Marta answered, eyes wide and fearful. Clint turned to the SHIELD agents clearing the debris, their action focused on the area directly above Aaron as confirmed by the satellite images command had supplied. The thought of being too late, of losing yet another member of his family was almost overwhelming. But he was a tactician, he thought in patterns, could plot moves. He needed more information. Facing Marta, he voiced his fear. “I want them to dig faster, but I’m afraid it’ll upset something and make things worse. What do you think? You heard what happened, I didn’t.” “I think we have to be careful, he said there was hardly any space as it was and I think something must have shifted. It’s like a game of Mikado, if you move one part another will move as well. We have to make sure not to aggravate his injuries,” she answered, and he saw her shaking minutely, but her voice remained firm. Newfound respect for Marta coursed through him. He smiled grimly at her and joined the other SHIELD agents at the mountain of rubble. He instructed them on how to proceed and they worked meticulously, carefully removing one part after the other. It was slow going and the fear for his brother was increasing with every passing minute. Marta kept trying to rouse Aaron, but there was no reply. She was pacing just off to the side, calling out to Aaron, talking to him even; he couldn’t understand what she said. And Aaron wasn’t answering. It was driving him nuts. The digging was going too slowly, seconds ticking by like hours. This was his brother buried under the rubble. A brother he had forgotten about for more than 30 years. Even if they had only known each other for four weeks, he didn’t want to think about losing him again. The rescue crew made it to the foundation now and when they removed a large piece of plywood from the rubble beneath he could see a glimpse of skin. They redoubled their efforts, carefully lifting a large beam and some smaller pieces of wood and then he was able to see Aaron’s chest moving. He was alive. Clint took a deep breath to calm himself, then turned towards Marta and beckoned her over with a wave of his hand. “We’ve got him, he’s alive,” he called out to her and everyone around them. She came to stand beside him, her fingers digging into his shoulder where he was crouched. His hand found her arm and he clamped down around it, needing the contact as much as she did. The SHIELD medics rushed over with their gear, ready to spring into action now that Aaron was freed. “He said his right arm was broken and something was off with his right leg. He’s also got a gunshot wound in his right shoulder; bullet is probably lodged in his shoulder blade,” Marta informed the medics. One of them, an athletic woman in her late forties, jumped into the hole with Aaron while her partner, a tall man, handed her the scoop stretcher she requested. “It’d be best if we got him out of here first. There’s hardly any room to operate as it is,” the senior medic said as she placed the two halves of the scoop under Aaron. The medic’s partner joined her once she was done and they lifted Aaron out of the hole where the scoop was received by SHIELD agents who carried it to the waiting transport stretcher. The medics received him, checked his vital signs, immobilized his arm and leg with air casts, bandaged his wound and fitted him with a pulse ox meter, a saline drip and an oxygen mask. It was all over in a couple of minutes and then they were moving back to the Medevac. Clint ushered Marta along as they followed the medics onto the quinjet, watched them settle Aaron for the transport as the hatch closed and the craft took flight. His heart was beating a frantic tattoo in his chest, wishing that he had medical knowledge beyond first aid and would be able to assess his brother more thoroughly himself. But even more, he wished not to be in this situation at all. It had been an unfortunate turn of events on a milk-run mission, and he would have traded places with Aaron in a heartbeat, he knew that. It had always been easier for him to endure physical pain than watch people he cared for suffer. Aaron remained stable throughout the flight back to the helicarrier. Once there, a slew of doctors and medics boarded and whisked him away to be examined and taken care of. Clint and Marta were stopped at the door to the exam room by two burly medics. Not wanting to delay the medical attention Aaron so desperately needed, Clint took Marta’s arm and they settled onto the soft leather bench in the waiting room. He slumped onto the comfortable seat, but he couldn’t relax, the adrenaline leaving him with a kind of hangover. Queasy, he felt a headache come on, so he closed his eyes to shut out the light. He felt Natasha’s presence before she actually touched him, so attuned was he to her energy. Opening his eyes as she slid into the seat next to him, he felt peace settle around him at the soft touch of her shoulder against his. His hand found its way into hers and she squeezed it, affectionately and reassuringly. He could breathe easier with her close, her skin on his was a soothing balm. He squeezed back as she settled against his side, tucking his arm around her shoulders. Her hand never let go of his. Natasha held Clint as they stood outside Aaron’s room. His face was burrowed in her hair, his breath harsh against her ear. One look inside and he had turned, walking out. She’d caught hold of him, wrapping him in her embrace, just like she’d done when she’d found him on the edge of the roof after they’d lost Barney. She had feared that her presence alone wouldn’t be enough to keep him with her. She couldn’t let him go. She angled them so that Clint had to look at Aaron when he raised his head. “Look at him,” she whispered, lips brushing his cheek as her hand cupped his jaw. It was trembling beneath her fingers, he clenched it so hard. She stroked gently over his bristly skin and felt him relax minutely. She smiled, her own worries subsiding as Clint exhaled audibly. Her Hawk would be okay, she knew it, she just had to make him see. “He’s alive because of you,” she added. “You did good, you saved him.” He raised his head and she watched him regard Aaron, his face expressionless, but worry clearly visible to her in his eyes. She couldn’t see Aaron, but she could imagine the pitiful sight Clint saw, with casts on his younger brother’s right arm and leg, his shoulder bandaged where the bullet had been removed. The monitors, the drip infusion, the oxygen cannula. Clint shivered and she held him closer, willing her calm to spill over into him. “He’s alive,” she repeated. “He’ll be okay, no lasting damage.” She felt the moment he focused on Aaron’s chest, rising rhythmically with each breath. Clint inhaled deeply, then exhaled slowly and she felt the muscles in his back uncoil, slowly, gradually. His heavily beating heart from a moment ago slowed to a normal rhythm and she allowed herself a small smile. He gently kissed her forehead, and when she looked at him the lines on his brow had smoothed out. She brushed her fingers across his jaw, and he leaned down, his warm lips found hers and she knew it would be alright. When he broke their kiss and disentangled himself from her this time, she didn’t hold him back. She let him go, knew where to find him later if he wasn’t in their shared quarters. He needed his solitude, and judging from the sounds coming from the room behind her, Marta needed a friend. She found the older woman sitting on the floor, her back pressed against the wall, her knees drawn to her chest. Her arms were slung around them and her back was shaking. Her sobs were muffled by the way she sat, but she was radiating misery. Natasha sat down beside her and put her hand on Marta’s shoulder, rubbing soothing circles onto it. “It’s okay,” Natasha said. “That’s a normal reaction.” Marta inhaled deeply, calming herself, then said, “Nothing about this situation is normal, not for me.” “Yet you were there,” Natasha calmly pointed out. “I made a choice, yes. I chose to stay. I chose to go with you.” Marta chuckled self-deprecatingly. “You know Aaron once said I’m a warrior? I’m no warrior.” “Not every warrior carries a gun,” Natasha answered. “You handled yourself well today.” “But I felt so helpless,” Marta insisted. Natasha remembered clenching her fist underneath tables as she listened to progress reports. The man on the bed looked so much like the man she loved that she didn’t need to stretch her imagination to know how Marta felt. The only difference was that she had been trained on how not to show it, while Marta didn’t. How much harder must it be for a civilian, someone who had no experience with the kinds of choices they were faced with every day? “Aaron’s alive because of you. You did good, you saved him,” Natasha repeated the words she’d said to Clint only a short while ago. “Thank you,” Marta said, a small smile spreading across her face. “I’m still never gonna leave my lab again.” Natasha smirked, her hand closing around Marta’s shoulder in a show of silent support. There was a rustle from the direction of Aaron’s bed and both women looked up, seeing the injured agent’s head turn towards them, grey eyes blinking open sluggishly. He mumbled something incomprehensible and held out his hand to Marta, his fingers beckoning her to him. She was on her feet, crossing the short distance separating them in no time and sat down on the edge of his bed. Natasha stayed where she was, knowing that her presence had already been forgotten. “I heard that,” she heard Aaron say, smiling tiredly, “never leaving your lab again?” “No, I’m locking myself in, and you with me,” Marta said as she bent down and kissed him. “But you only have the fridge for the samples,” he said as they parted. “Where’re we gonna keep our food?” “Food? Really? That’s your biggest concern?” she asked, a smile lighting up her face. Natasha got up as she saw the tension flow from the other woman’s body. She would be okay, as would Aaron. Her heart was full as she slunk out of the room, wanting nothing else but find her archer and hold him close. She cast a last look at the scene before her as she left the room. Aaron held Marta’s hand; she was brushing her fingers through his hair as he yawned. “No, you are,” he replied, his eyes closing as he drifted back to sleep. All she could do was try, Natasha thought, but she would do her best to make sure her family was safe. 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FOR IMMEDIATE RELEASE BERKELEY REPERTORY THEATRE EXTENDS AIN'T TOO PROUD—THE LIFE AND TIMES OF THE TEMPTATIONS By popular demand, fifteen performances added – now playing through Sunday, October 22 September 7, 2017 – Due to an overwhelming demand, Berkeley Rep has announced that the world premiere musical of Ain't Too Proud—The Life and Times of The Temptations will extend for two additional weeks. Originally scheduled to close on October 8, the popular musical will now run through Sunday, October 22. Starting today, tickets for the added fifteen performances can be purchased online at berkeleyrep.org and by phone at 510 647-2949. An electrifying new musical about the life and times of The Temptations, the greatest R&B group of all time (Billboard Magazine 2017). They were five young guys on the streets of Detroit when they were discovered by Berry Gordy, who signed them to his legendary new label. After 24 attempts, they finally had a hit and the rest is history—how they met, how they rose, the groundbreaking heights they hit, and how personal and political conflicts threatened to tear the group apart as the nation fell into civil unrest. Kennedy Prize-winning playwright Dominique Morisseau, Olivier Award-winning choreographer Sergio Trujillo, and two-time Tony Award-winning director Des McAnuff bring you this thrilling story of brotherhood, family, loyalty, and betrayal. Iconic hits like “My Girl,” “Just My Imagination,” and “Papa Was a Rolling Stone” and the signature dance moves that made the “Classic Five” Temptations part of our cultural history forever. Cast member include Esther Antoine (Swing), Derrick Baskin (Otis Williams), Shawn Bowers (Lamont), Jeremy Cohen (Shelly Berger), E. Clayton Cornelious (Richard Street), James Harkness (Paul Williams), Rodney Earl Jackson, Jr. (Swing), Taylor Symone Jackson (Johnnie Mae), Jared Joseph (Melvin Franklin), Jahi Kearse (Berry Gordy), Jarvis B. Manning, Jr. (Al), Jeremy Pope (Eddie Kendricks), Devin L. Roberts (Swing), Rashidra Scott (Josephine), Charles G. LaPointe (Al), Ephraim Sykes (David Ruffin), Nasia Thomas (Mama Rose), Christian Thompson (Smokey Robinson), and Candice Marie Woods (Diana Ross). The creative team includes Robert Brill (scenic designer), Paul Tazewell (costume designer), Howell Binkley (lighting designer), Steve Canyon Kennedy (sound designer) Peter Nigrini (projection designer), Charles G. LaPointe (hair and wig designer), and Steve Rankin (fight director). Orchestrations are by Harold Wheeler with Music Direction and Arrangements by Kenny Seymour. ************************************************************************************************************* CREATIVE TEAM Dominique Morisseau (Book) Dominique is the author of The Detroit Project (A 3-Play Cycle), which includes the following plays: Skeleton Crew (Atlantic Theater Company), Paradise Blue (Williamstown Theatre Festival), and Detroit '67 (Public Theater, Classical Theatre of Harlem, and National Black Theatre). Additional plays include Sunset Baby (Labyrinth Theater Company), Blood at the Root (National Black Theatre), and Follow Me to Nellie’s (Premiere Stages). Her work has been commissioned by the Hip Hop Theater Festival, Steppenwolf Theatre Company, Women's Project Theater, South Coast Rep, People’s Light and Theatre, and Oregon Shakespeare Festival/Penumbra Theatre. She currently serves as co-producer on the Showtime series *Shameless*. She has received the Stavis Playwriting Award, an NAACP Image Award, a Spirit of Detroit Award, the Weissberger Award, a PoNY Fellowship, the Sky Cooper New American Play Prize, a TEER Spirit Trailblazer Award, the Steinberg New Play Award, the Edward M. Kennedy Prize for Drama (*Detroit '67*), an Audelco award, and an Obie Award (*Skeleton Crew*). **Des McAnuff** (Director) Des is a two-time Tony Award-winning director and former artistic director of the Stratford Festival. He is also director emeritus of La Jolla Playhouse, where during his tenure he directed more than 30 productions. His Broadway credits include *Doctor Zhivago, Jesus Christ Superstar, Guys and Dolls*, Aaron Sorkin’s *The Farnsworth Invention*, *Jersey Boys* (Tony and Olivier Awards: Best Musical), *Billy Crystal’s 700 Sundays* (Tony Award: Best Special Theatrical Event), *Dracula the Musical, How to Succeed in Business Without Really Trying*, *The Who’s Tommy* (Tony and Olivier Awards: Best Director), *A Walk in the Woods*, and *Big River* (Tony Awards: Best Director, Best Musical). His Stratford highlights include *A Word or Two, Caesar and Cleopatra*, and *The Tempest* (all with Christopher Plummer). Opera: *Faust* (Metropolitan Opera, English National Opera). Film: *Cousin Bette* (director), *Iron Giant* (producer, BAFTA Award), and *Quills* (executive producer). In 2012, Des was awarded Canada's esteemed Governor General’s National Arts Center Award and the Order of Canada. **Sergio Trujillo** (Choreographer) Broadway credits include *On Your Feet* (Tony Award nominee, Outer Critics Circle/Astaire Awards, *Memphis* (Olivier/ OCC Award, Drama Desk/Astaire Award nominations), *Jersey Boys* (Drama Desk/OCC/Greenroom/Dora nominations), *A Bronx Tale* (Chita Award nomination), *Addams Family, Next to Normal, Hands on a Hardbody* (Drama Desk nomination), *Leap of Faith* (Drama Desk nomination), *Guys and Dolls* (Astaire Award nomination), and *All Shook Up*. Other theatre: *Arrabal* (ART), *Invisible Thread* (Second Stage), *Carmen: An Afro-Cuban Musical* (Olney Theatre — Helen Hayes Award nomination), *Freaky Friday* (Signature Theatre), *Flashdance* (national tour), and *The Wiz* (La Jolla Playhouse). International: *Tarzan* (Disney), *Peggy Sue Got Married* (West End), *The Sound of Music* and *West Side Story* (Stratford Festival). **Harold Wheeler** (Orchestrations) Harold is a composer, arranger, orchestrator, musical director, musical supervisor, and musician. Perhaps best known for his 17 seasons as musical director of the ABC show *Dancing with the Stars*, he has enjoyed many years of success over several mediums. Broadway credits include *Side Show, Hugh Jackman—Back on Broadway, Dirty Rotten Scoundrels* (Tony Award nomination), *Never Gonna Dance, Hairspray* (Tony Award nomination, Drama Desk Award), *The Full Monty* (Tony Award nomination), *Swing!* (Tony Award nomination), *Little Me* (Tony Award nomination), *The Life* (Tony Award nomination), *Dreamgirls, The Wiz, The Tap Dance Kid*, and *Lena Horne: The Lady and Her Music*. He has served as conductor of the Academy Awards three times (most recently during the 89th Academy Awards), only the second African-American conductor in the Academy’s history. He also was one of two conductors during the closing ceremonies of the 1996 Summer Olympics. In 2008, Harold received a Lifetime Achievement Award from the NAACP Theatre Awards. He is married to television and Broadway performer Hattie Winston. **Robert Brill** (Scenic Designer) Robert is thrilled to return to Berkeley Rep, having previously designed *The Laramie Project*. Broadway credits include *Assassins* (Tony Award nomination), as well as the set and club design for the critically acclaimed revival of *Cabaret, Jesus Christ Superstar, Guys and Dolls*. (Tony Award nomination), Buried Child, Design for Living, A Streetcar Named Desire, One Flew Over the Cuckoo’s Nest, and others. His credits include Disney’s Frozen, as well as numerous opera world-premieres, including Moby-Dick, Everest, Cold Mountain, and It’s a Wonderful Life. He has designed for the Whitney Museum of American Art, BAM, Stratford Shakespeare Festival, the Guthrie Theater, Goodman Theatre, Steppenwolf Theatre, La Jolla Playhouse, Oregon Shakespeare Festival, and American Conservatory Theater. Upcoming: Summer, The Donna Summer Musical, directed by Des McAnuff. Robert is a founding member of Sledgehammer Theatre, a recipient of the Michael Merritt Award for Excellence in Design and Collaboration, and professor of Scenic Design for the University of California, San Diego. Paul Tazewell (Costume Designer) Paul has been designing costumes for Broadway, regional theatre, film and television, dance, and opera productions for over 25 years. Starting his Broadway career with the groundbreaking musical, Bring in ’Da Noise, Bring in ’Da Funk directed by George C. Wolfe, he followed that with work on the original Broadway productions of the Pulitzer Prize- and Tony Award-winning Hamilton; In the Heights; The Color Purple; Dr. Zhivago; Memphis; Caroline, or Change; Elaine Stritch at Liberty; Russel Simmons’ Def Poetry Jam; Lombardi; and Magic/Bird. Revival work includes Side Show, A Streetcar Named Desire, Jesus Christ Superstar, Guys and Dolls, A Raisin in the Sun, and On the Town. He has received many recognitions for his work. In the same year, 2016, he received both a Tony Award, for Hamilton, and the Emmy Award, for The Wiz! Live on NBC. That summer, he also designed The Immortal Life of Henrietta Lacks for HBO Films starring Oprah Winfrey and based on the best-selling book. He currently lives in New York City and works across the globe. Howell Binkley (Lighting Designer) Broadway credits include Come From Away (Tony Award nomination), Hamilton (Tony Award), A Bronx Tale, How to Succeed in Business Without Really Trying, Jersey Boys (Tony Award), In the Heights, Gypsy, Xanadu, Cry-Baby, LoveMusik, Bridge & Tunnel, Steel Magnolias, Avenue Q, Golda’s Balcony, Hollywood Arms, Gore Vidal’s The Best Man, Minnelli on Minnelli, The Full Monty, Parade, Kiss of the Spider Woman, High Society, and Grease. Off-Broadway credits include Landscape of the Body, Sinatra, Batboy, and Radiant Baby. Steve Canyon Kennedy (Sound Designer) His Broadway credits as production sound engineer include Cats, Starlight Express, Song and Dance, The Phantom of the Opera, Aspects of Love, and Carrie. Broadway sound design credits include On Your Feet, Dr. Zhivago, Lady Day at Emerson’s Bar and Grill (Tony Award), Hands on a Hardbody (Drama Desk Award), Jesus Christ Superstar, Catch Me If You Can (Tony Award nomination), Guys and Dolls, Mary Poppins, The Lion King, Jersey Boys (Drama Desk Award), 700 Sundays, Hairspray, The Producers, Aida, Titanic, Big, How to Succeed in Business Without Really Trying, Carousel, and The Who’s Tommy (Drama Desk Award). Peter Nigrini (Projection Designer) Peter most recently worked on the world premiere of Monsoon Wedding at Berkeley Rep. Broadway credits include A Doll’s House, Part 2, Amelie, A New Musical, Dear Evan Hansen, An Act of God, Heidi Chronicles, The Best Man, Fela, and 9 to 5. His other New York credits include Grounded and Here Lies Love (the Public Theater), Wakey, Wakey (Signature Theatre), The Elaborate Entrance of Chad Deity (Second Stage Theatre), Notes from Underground (Yale Repertory Theatre), The Grace Jones Hurricane Tour, Rent (New World Stages), Real Enemies (Barn Next Wave Festival, and Blind Date (Bill T. Jones). For Nature Theater of Oklahoma, No Dice and Life & Times (Burgtheater, Vienna). His upcoming projects are Lucia di Lammermoor (Santa Fe Opera) and The SpongeBob Musical (Broadway 2017-18). Wiz Live! (Emmy Award nomination). Charles’ upcoming Broadway credits include The Band’s Visit and SpongeBob SquarePants. Steve Rankin (Fight Director) Steve’s previous Berkeley Rep credits include Yellowjackets, Ruined, and Mother Courage. His Broadway credits include Doctor Zhivago, Jersey Boys, Memphis, The Who’s Tommy, Two Shakespearean Actors, The Farnsworth Invention, Henry IV, Twelfth Night, Macbeth, Getting Away with Murder, Anna Christie, Dracula, The Real Inspector Hound, and Guys and Dolls. Off Broadway, he has worked on The Third Story, Below the Belt, and The Night Hank Williams Died. His Stratford Shakespeare Festival credits include Romeo and Juliet, Macbeth, and Caesar and Cleopatra. He worked on Rodelinda, Faust, and Iphigenia at Tauride, all at the Metropolitan Opera. Regionally, he has worked at La Jolla Playhouse, the Old Globe (associate artist), the Mark Taper Forum, Ahmanson Theatre, Actors Theatre of Louisville, Asolo Repertory Theatre, Paper Mill Playhouse, and Center Stage, among others. Steve also plays mandolin with Susie Glaze and the New Folk Ensemble. CAST Esther Antoine (Swing) Esther is excited to join the Berkeley Rep family in this production of Ain’t Too Proud. Her national tour credits include Matilda The Musical, Catch Me If You Can, and Memphis. Her New York City credits include Candide and Los Elementos (New York City Opera). Her regional credits include The Wiz (Arkansas Repertory Theatre), The Wizard of Oz (Westchester Broadway Theatre), and Dreamgirls (North Shore Music Theatre). Some of her other credits include performances at the Blue Note, the Apollo Theater, and Madison Square Garden. Derrick Baskin (Otis Williams) Derrick is making his Berkeley Rep debut. An award-winning actor, he was last seen on the New York stage in Who’s Inside a Loop. He originated roles in two Tony Award-winning musicals, Memphis and The 25th Annual Putnam County Spelling Bee (Drama Desk Award), and also originated a role in The Little Mermaid, working alongside Oscar, Grammy, Tony winning composer Alan Menken and Pulitzer prize author Doug Wright. He is best known for his role in the critically acclaimed Hulu sitcom Difficult People, currently in its third season, and his recurring role on Law and Order: Special Victims Unit. Other film credits include the remake of Annie, starring Cameron Diaz and Jamie Foxx, directed by Will Gluck; and Anesthesia, starring Glenn Close, directed by Tim Blake Nelson. Derrick’s concert experience includes performances with Wynton Marsalis, Michael Bublé, Wiz Khalifa, Mariah Carey, and he has written songs on former Beyoncé musical director, Divinity Roxx’s, debut album I’m Possible. Shawn Bowers (Lamont) Shawn is thrilled to be making his Berkeley Rep debut! He is ecstatic to take part in the world premiere production of Ain’t Too Proud. Originally from St. Louis, he now resides in New York City. Earlier this year, he participated in the developmental production of the new original musical, Back Home Again, which had a limited run in Walnut Creek at the Lesher Center for the Arts. He travelled the high seas in the Broadway production of the big band jazz-age musical After Midnight. Regional credits include Beauty and the Beast, Grease, and The Addams Family. Favorite roles: Rent (Benny), Parade (Newt Lee/Riley), The Little Mermaid (Sebastian), and Mary Poppins (Robertson Ay). Jeremy Cohen (Shelly Berger) Jeremy is making his Berkeley Rep debut. On Broadway, he appeared opposite Tyne Daly in Manhattan Theatre Club’s Tony Award-nominated production of Master Class. He later reprised his role for the London transfer. Other New York credits include On Your Toes (City Center Encores), Once Upon a Time in New Jersey (Prospect Theatre Company), Alain Boublil’s Manhattan Parisienne (59E59), and the long-running off-Broadway hit Old Jews Telling Jokes. Regional credits include work at the Kennedy Center, Alliance Theatre, Milwaukee Repertory Theater, Delaware Theatre Company, and Kenny Leon’s True Colors Theatre. Television and film credits include Blue Bloods (CBS), Shades of Blue (NBC), and Supporting Characters (Tribeca Film Festival). Jeremy composed the music for The Bowery Boys (Marriott Theatre), which received a Chicago Jeff Award nomination for Best New Musical. He is a proud Northwestern graduate. E. Clayton Cornelious (Richard Street) Clayton is making his debut at Berkeley Rep. He is a Pittsburgh native who has been working on Broadway for nearly 20 years. Broadway credits include the Caterpillar in Wonderland, Beautiful: The Carole King Musical, The Scottsboro Boys, A Chorus Line, The Music Man, Kat & the Kings, and The Lion King. National Tours include Kinky Boots, Sister Act, Jersey Boys, Dirty Dancing, Hairspray, The Lion King, A Chorus Line, The Goodbye Girl, and The Wiz. His West End credits include Sammy Davis Jr. Jr. in Rat Pack Live from Vegas! TV/Film credits include One Life to Live and Meet Dave with Eddie Murphy. He is a proud member of BIV (Broadway Inspirational Voices). James Harkness (Paul Williams) James is making his Berkeley Rep debut. His Broadway credits include The Color Purple and Aida. His regional credits include Dreamgirls, Applause, Purlie, Can-Can, Mama I Want to Sing (AMAS; Minister of Music). Rodney Earl Jackson, Jr. (Swing) Rodney is honored to be making his Berkeley Rep debut. He made his Broadway debut in The Book of Mormon after graduating with a BFA from Carnegie Mellon University's School of Drama. He was last seen traveling North America in the first national tour of Motown: The Musical. A San Francisco native who was discovered in his public elementary school at age 9, Rodney continued his theatre and performance education at Rec and Park’s Young People’s Teen Musical Theatre Company, and graduated from the Ruth Asawa School of the Arts’ theatre department. He is now the artistic director and co-founder of the San Francisco Bay Area Theatre Company (BATCO), a nonprofit theatre company whose mission is to culturally diversify the theatre scene of the Bay Area by producing live theatre that is reflective of the authentic perspectives and history of the San Francisco Bay Area. Taylor Symone Jackson (Johnnie Mae) Taylor is excited to be making her Berkeley Rep debut. Her regional credits include The Wiz and Oklahoma (Oregon Shakespeare Festival) and Shakin’ the Mess Outta Misery (Spelman College). Her New York credits include Becoming David (Playwrights Horizons), Find (Nuyorican Poets Cafe), and Viva Las Vegas (AMDA). Her TV credits include My Parents, My Sister & Me; The Game; and Girl, Get Your Mind Right. She is also trained in various styles of dance from the Atlanta Ballet and acting at the Freeman Studio. She is a native of Atlanta, Georgia, and now lives in New York. Jared Joseph (Melvin Franklin) Jared is a New York-based actor making his Berkeley Rep debut. He was last seen in the Bay Area in American Conservatory Theater’s production of The Scottsboro Boys (Mr. Bones). His regional theatre credits include Hair: Retrospection (Kansas City Repertory Theatre) and The Parchman Hour (the Guthrie Theater). New York/Broadway credits include Holler If Ya Hear Me, The Book of Mormon, Encores! Cabin in the Sky, and Radio City Christmas Spectacular. National tour includes Dreamgirls and The Book of Mormon (Latter Day Tour). Film/TV: Unbreakable Kimmy Schmidt and Black Nativity. Jared holds a BFA from New York University. Jahi Kearse (Berry Gordy) Jahi, an Atlanta, Georgia, native living in New York, is making his debut at Berkeley Rep. His Broadway credits include Holler If Ya Hear Me (the Palace Theater) and Baby It’s You! (the Broadway Theatre). Off-Broadway credits include The Total Bent; The Fortress of Solitude (the Public Theater), and select regional credits include Lungs, Satchmo at the Waldorf, and Bars & Measures (B Street Theatre); Indian Joe (Goodspeed Musicals); Maurice Hines’ Yo Alice (Radio City Music Hall); Debbie Allen’s Souls Possessed; Seussical The Musical (the Alliance Theatre); Passing Strange, Motherf**ker with the Hat, and Topdog/Underdog (the Studio Theatre); Gut Bucket Blues, Sly of the Blind Pig, and Two Trains Running (True Colors Theatre). Jahi is a proud alumni of the Freddie Hendricks Youth Ensemble of Atlanta and Tri-Cities High School for the Visual & Performing Arts. Jarvis B. Manning, Jr. (Al) Jarvis, a native of Houston, Texas, is extremely proud to be making his Berkeley Rep debut. His favorite performance credits are Jackie Wilson, Eddie Holland, Billy Gordon, and Rick James. He portrayed these musical legends in the first national tour of Motown: The Musical, and on Broadway at the Nederlander Theatre. He received his educational foundation from the legendary High School for the Performing and Visual Arts (HSPVA) and the American Music and Dramatic Academy (AMDA NY). Jeremy Pope (Eddie Kendricks) Jeremy is making his Berkeley Rep debut. He was a Drama League nominee alongside Denzel Washington and James Franco for his lead role as Pharus in Choir Boy (Manhattan Theatre Club) written by Tarell Alvin McRanney. Off-Broadway credits include Invisible Thread directed by Diane Paulus and The View Upstairs. Jeremy is also a photographer published in Vogue and Cosmopolitan magazine as well as recording artist. Devin L. Roberts (Swing) Devin is making his Berkeley Rep debut. He appeared on Broadway in The Lion King. He also appeared in Cabin in the Sky and Do I Hear a Waltz? (City Center Encores). Off-Broadway roles include Romy and Michele’s High School Reunion, Venice (the Public Theater), and Soul Doctor (New York Theatre Workshop). Regional credits include Stagger Lee (Dallas Theater Center), Chicago (North Shore Music Theatre), Smokey Joe’s Cafe (Theatre Under the Stars), and Hairspray (Walnut Street Theatre). TV credits include Smash, Tony Awards 2012, and America’s Got Talent. Rashidra Scott (Josephine) Rashidra is making her Berkeley Rep debut. Favorite regional credits include Reno in Anything Goes (Goodspeed Opera House), Deloris in the regional premiere of Sister Act (Ogunquit Playhouse and Gateway Playhouse), Lorrell in Dreamgirls (Marriott Theatre in Lincolnshire), Hairspray (Paper Mill Playhouse), Little Shop of Horrors (Stages St. Louis, Kevin Kline nomination), and Dionne in Hair (Arizona Theatre Company). Her Broadway credits include Beautiful: The Carole King Musical (original Broadway company, Grammy Award), Sister Act (original Broadway company, U/S Deloris; first national tour, Deloris), Hair (U/S Abe Lincoln), Finian’s Rainbow (U/S Dolores), and Avenue Q (Gary Coleman). Other favorite credits include Nala in the opening cast of Hong Kong Disneyland’s Festival of the Lion King among other Walt Disney World Entertainment productions and appearing on Rescue Me (Sony/FX) as Violet the singing nurse. Rashidra has a BM in Music Business/Management from Boston’s Berklee College of Music. Caliaf St. Aubyn (Dennis) Caliaf is an artist who strives to entertain his audience with hopes that they leave each and every performance feeling fulfilled. This will be his Berkeley Rep debut. Some of his accomplishments are performing with one of his mentors, Gregory Hines, in the Showtime movie Bojangles and sharing the stage with the incomparable Ms. Patti LaBelle and Sam Smith. He was involved in the Smokey Joe’s Café 20th anniversary tour, and had a featured role in the 2013 film, Admissions. He also played the role of Jimmy Early in the production of Dreamgirls at the Gallery Players Theater in Brooklyn, NY, in 2013. This resulted in his nomination for the 2013 Audelco “Outstanding Performance in a Musical” award and the 2013 New York Innovative Theatre “Outstanding Actor in a Featured Role” award. More recently he was involved in the Broadway musical, Beautiful: The Carole King Musical. Ephraim Sykes (David Ruffin) Ephraim is making his Berkeley Rep debut. A native of St. Petersburg, Florida, Ephraim made his Broadway debut in The Little Mermaid and was in the original casts of Hamilton: An American Musical, Memphis, Newsies, and Motown: The Musical. He was last seen as Seaweed J. Stubbs on NBC’s Hairspray Live!. Ephraim graduated from the Alvin Ailey/Fordham University BFA program with departmental honors and toured with the Aliley II company for two years. His TV/film credits include Marvin in HBO’s Vinyl, Woody Allen’s Crisis in Six Scenes, Marvel’s Netflix series Luke Cage, Leave It on the Floor, Dance Flick, CBS’ NYC 22, NBC’s Smash, 30 Rock, and Kathryn Bigelow’s new feature film Detroit, now in theatres. Nasia Thomas (Mama Rose) Nasia is making her Berkeley Rep debut. She was recently seen as Little Eva in Beautiful: The Carole King Musical on Broadway. Her other credits include the national tour of Beautiful: The Carole King Musical (swing). Regional credits include Hairspray (the Muny) and The Buddy Holly Story. Other credits The Wiz (Dorothy), Les Misérables (U/S Fantine), and Dreamgirls (U/S Effie). Nasia is a graduate from Elon University where she received her BFA in Music Theatre, 2015. Christian Thompson (Smokey Robinson) Christian is thrilled to be making his Berkeley Rep debut. He recently ended his run as Benjamin Coffin III, as well as the U/S Roger, in the 20th anniversary tour of Rent. Other recent credits include De’André in Blood at the Root (National Black Theatre of Harlem) and Tap Brother 2 in After Midnight (Norwegian Escape). Christian received his BFA in Musical Theatre from the Pennsylvania State University, Crew ’15. Candice Marie Woods (Diana Ross) Candice is making her Berkeley Rep debut. A native of Texas, she has performed all over the United States and Canada. Most recently, she appeared as Deena Jones in the Worklight Production/OD Company Korean tour of Dreamgirls. Her Broadway credits include Hairspray, Catch Me If You Can, Women on the Verge of a Nervous Breakdown, Nice Work If You Can Get It, and The Book of Mormon. National tours include Dirty Dancing: The Classic Story on Stage and Legally Blonde. She is a proud member of Actors’ Equity Association. For the 2017-18 season Berkeley Rep recognizes the generosity of season sponsors of BART, Peet’s Coffee, and Wells Fargo. Ain’t Too Proud—The Life and Times of The Temptations is also made possible by the support of individual season sponsors Michael and Sue Steinberg. Executive sponsors are Jean and Michael Strunsky and The Ira and Leonore S. Gershwin Philanthropic Fund, and sponsors are Mechanics Bank Wealth Management. ABOUT BERKELEY REP Berkeley Repertory Theatre has grown from a storefront stage to an international leader in innovative theatre. Known for its core values of imagination and excellence, as well as its educated and adventurous audience, the nonprofit has provided a welcoming home for emerging and established artists since 1968. In four decades, four million people have enjoyed nearly 400 shows at Berkeley Rep. These shows have gone on to win five Tony Awards, seven Obie Awards, nine Drama Desk Awards, one Grammy Award, and many other honors. In recognition of its place on the national stage, Berkeley Rep received the Tony Award for Outstanding Regional Theatre in 1997. Its bustling facilities – which include the 400-seat Peet’s Theatre, the 600-seat Roda Theatre, the Berkeley Rep School of Theatre, and a spacious campus in West Berkeley – are helping revitalize a renowned city. Learn more at berkeleyrep.org. # # #
Part One: "The Man Who Loved Cities" Eugenie L. Birch Charles E. Little Ann Louise Strong Thomas Balsley Albert LaFarge See next page for additional authors PART ONE “The Man Who Loved Cities” This page intentionally left blank Among many tributes paid to William H. “Holly” Whyte after his death in 1999, Norman Glazer (1999) characterized him in the Wilson Quarterly as “the man who loved cities . . . one of America’s most influential observers of the city and the space around it.” It is fitting to devote Part I of this book to personal recollections of this perceptive urbanist written by several people who knew him well in different capacities and at different periods in his career. Ann Louise Strong, emerita professor of law at the University of Pennsylvania, worked closely with Whyte on the pathbreaking open space plan for the Brandywine Valley in the mid-1960s. Another Penn colleague, the late landscape architect Ian McHarg, drew strongly on the Brandywine plan in his seminal 1968 book, Design with Nature. In his turn, Whyte touted McHarg’s ideas in his own 1968 classic, The Last Landscape. Also in the mid-1960s, Charles E. Little had the good fortune to encounter Whyte as a board member of the New York Open Space Institute, of which Little was chief executive officer. Little eschewed being an “organization man” after reading Whyte’s 1956 book of that title and instead applied his talents to making metropolitan New York a more habitable and “humane” place in which to live and work. At the Open Space Institute, Little authored two books on land conservation: Stewardship and Challenge of the Land (which in turn influenced this editor’s first effort, Open Space in Urban Illinois, Platt 1971). Subsequently, in the Washington, D.C., area and now in New Mexico, Little has contributed his literary and practical experience to many land-saving and regional planning efforts such as farmland preservation, “greenline parks,” and sacred Native American sites. Eugenie L. Birch, while a Hunter College urban planning professor and member of the New York City Planning Commission, collaborated with Whyte in his “Street Life Project”—the basis for his book and film, The Social Life of Small Urban Spaces, and his capstone book, City: Rediscovering the Center—during the 1980s. Birch would build on Whyte’s passion for lively city centers in her own research on downtown revitalization. Thomas Balsley, a practitioner of people-oriented urban design, has had many opportunities to apply lessons taught by Whyte. As a personal friend and sometime collaborator, Balsley helped realize Whyte’s visions as to what works or fails in terms of people interaction and enjoyment in shared urban spaces. Albert LaFarge became a Holly Whyte fan toward the end of Whyte’s career. As a frequent visitor to the East Ninety-fourth Street brownstone where the Whytes lived, LaFarge assumed the role of Boswell to Holly’s Johnson. The result was *The Essential William H. Whyte* (LaFarge 2000), which draws from all Whyte’s writings the very best of his wit and wisdom. **References** William H. Whyte (The Observation Man) left a remarkable body of writing that addressed three principal aspects of the United States after World War II: 1. The sociology of large organizations and their new suburban habitats (The Organization Man, 1956) 2. Suburban land use and sprawl (two essays in Editors of Fortune; The Exploding Metropolis, 1957; Securing Open Space for Urban America: Conservation Easements, 1959; Cluster Development, 1964; and The Last Landscape, 1968) 3. The functions and design of public spaces in urban settings (The Social Life of Small Urban Places, 1980; City: Rediscovering the Center, 1988). Only today, as we are rebuilding lower Manhattan and other downtowns while confronting runaway suburban sprawl across the nation, are we realizing the prescience of this remarkable urbanist and his work. His understanding that economic concentration and population density at the center of a region is the key to conserving land at its periphery made him a pioneer of today’s “smart growth” movement. Furthermore, he provided the theory and techniques for achieving model land use arrangements that contemporary city planners and metropolitan policy makers now vigorously promote. A keen and sensitive observer of his surroundings, Whyte first approached an issue intuitively, but once he had a handle on it, he pursued it in depth, forging his own research methods. He read widely on the given subject, he talked to experts, but most important, he did field research, always questioning the so-called conventional wisdom. When he finally synthesized it all, he provided, in every instance, a new take on the selected topic that blended intelligence, wit, and common sense. This process was the source of his originality because, like Frederic Law Olmsted and other “enlightened amateurs,” he was not trained in the field that he would help transform, namely urban planning and design. He picked up the basics as he went along: markets and economics from his experience as an editor at Fortune magazine; sociology from studying corporate life in Park Forest, Illinois; and land use planning from observing suburban development around his childhood home in Chester County, Pennsylvania, and from his consultancy on New York City’s comprehensive plan. Whyte was a modern Renaissance man, a practical humanist, who became an authority on the burning issues of his day through self-education and intelligent observation (figure 1). In addition, he took his knowledge beyond articles, chapters, and books; he translated it into legislation and principles of urban design practice. He trained a generation of influential scholars and civic leaders. His insights on the use and design of urban public space are still fresh today. A year after his death in 1999, Fordham University Press printed a compendium of some of his best writings in *The Essential William H. Whyte* (LaFarge 2000), and the University of Pennsylvania Press reprinted *The Last Landscape* in 2001 and *The Organization Man* in 2002 (it also plans to reissue *The City: Rediscovering the Center*). *The Social Life of Small Urban Spaces* (1980) is marketed by the Project for Public Spaces, a design firm that Whyte helped found. (See Andrew G. Wiley-Schwartz’s essay in this volume.) In 1985, Whyte was elected an honorary member of the American Institute of Certified Planners (AICP) for his “outstanding contribution . . . to the development of the planning profession.” (Also honored at the time were Lewis Mumford, the distinguished urban historian, and James Rouse, the builder of Columbia, Maryland, and originator of the concept of “festival malls.”) The AICP cited Whyte’s “constructive influence on understanding subdivision growth, conversion of open space, cluster development, urban beautification, revitalization of central cities and the social life of small urban places” (Singer 1985). At this time I was invited to write the article (Birch 1986) about Whyte for Planning magazine that later appeared under the title “The Observation Man” (a title the New York Times Magazine borrowed in a short profile of Whyte in its “People of the Millennium” issue of January 2, 2000). On a crisp, clear autumn day in 1985, Holly Whyte invited me to his office high above midtown Manhattan in Rockefeller Center where at age sixty-nine he was actively consulting and writing under the sponsorship of his longtime friend Laurance S. Rockefeller. We spent a few intense hours discussing his life, ideas, and many projects while overlooking Whyte’s world: the glittering buildings of midtown Manhattan, the shimmering Hudson River, the New Jersey waterfront, and the hazy hills of the Garden State beyond. He had spent a lifetime puzzling over the various elements that made up the regional landscape, and he was eager to share his accumulated insights. Whyte recalled his postgraduate days, portraying a raw Princeton University English major turned traveling salesman, peddling Vicks VapoRub during the Depression. He admitted that World War II had rescued him from that life. As a Marine intelligence officer, he began to develop a lifelong interest in geographic data, as later recorded in his final memoir, A Time of War: Remembering Guadalcanal, A Battle without Maps (Whyte 2000). After the war, he secured an editorial job at Fortune magazine, which at that time allowed a very broad interpretation of business journalism. He relished the extended time spent in the new white-collar Chicago suburb of Park Forest, Illinois, researching the series on the modern corporate worker that would be a key element of The Organization Man, his most successful book. In the early 1950s, Whyte and several colleagues, including Jane Jacobs, wrote a series of articles that were republished as The Exploding Metropolis (Editors of Fortune 1957). That small book would become required reading for many planning students; Charles Abrams, head of the Columbia University planning program, considered it the best work in the field. In the next few years, Whyte’s urban philosophy would broaden and mature. In the early 1960s, his role as consultant to the Outdoor Recreation Resources Review Commission, chaired by Laurence S. Rockefeller, the philanthropic conservationist, stimulated his interest in techniques to retain open space in the process of suburban development, resulting in his professional reports on “conservation easements” and “cluster development.” In the mid-1960s, Whyte was retained by Donald H. Elliott, chair of the New York City Planning Commission, to overhaul editorially the city’s draft Comprehensive Plan. Finding that the plan contained masses of data but lacked a clear message, Whyte rewrote much of it, producing a document that the New York Times described as “probably the most clearly written plan ever published.” The plan’s “Critical Issues” section, which best reflects Whyte’s graceful writing style and enthusiasm for urban life, begins: There is a great deal that is very right with New York City. As never before it is the national center of the United States . . . there is more of everything here that makes a city jump and hum with life—more of different kinds of people, more specialized services, more stores, more galleries, more restaurants, more possibilities of the unexpected. Here is the engine. And it is getting stronger. . . . Concentration is the genius of the City, its reason for being, the source of its vitality and its excitement. We believe the center should be strengthened, not weakened, and we are not afraid of the bogey of high density. (New York City Planning Commission 1969, vol. 1, p. 5) In helping rewrite the 1969 Comprehensive Plan, Whyte encountered “incentive zoning,” a technique added to the New York City zoning ordinance in 1961 that gave developers extra floor space in exchange for providing an urban plaza or public arcade at their expense. Employed extensively along the rapidly developing Sixth Avenue, the results, according to Whyte (and many other critics) were mixed. Although the city had gained additional open space, the sites were, in general, disappointing. They were poorly designed, unattractive, and, as a consequence, underused. The discouraged planners, Whyte related, were ready to eliminate the incentives, but he cautioned them “not to throw the baby out with the bathwater.” Convinced that the law could stand if improved, he set out to discover what was needed. Following his by now-proven research method of information gathering, observation, and synthesis, he established the Street Life Project, based at Hunter College and funded by the National Geographic Society, the Rockefeller Brothers Fund, and others. His eyes lit up as he described his techniques: the time-lapse photography, the miles of film footage to review, and the joy of finding behavioral patterns. He clearly loved “spying” on his urbanites. He was amused by their spontaneous street conversations and the variety of their interchanges on street corners and at building entrances. Characteristically, he used the word schmoozing to typify street conversations. A stiff scholar would never have used such a term, but Whyte was not stiff. He was, however, systematic: he gathered empirical data and translated the information into an organized set of planning principles that New York City would incorporate into its 1975 zoning ordinance revision. Other cities would follow suit. This work was not guesswork; his greatest strength was his extreme attention to detail—exact measurements of the width of a sitting ledge, the amount of sitting space measured in linear feet related to the square footage of a plaza—to arrive at appropriate legislative formulas. As of 1985, ten years after the zoning revisions, he felt strongly about the need to evaluate and refine these ideas. No one would take him up on his idea until the mid-1990s, when the New York Department of City Planning collaborated with Harvard professor Jerold S. Kayden and the Municipal Art Society to inventory and assess the entire stock of incentive-based public space. (See Kayden’s essay in this volume.) What Holly Whyte wanted most was to craft the outdoor elements of downtown so that they could support and enhance the processes that make “the city jump and hum with life.” His larger purpose was to create an environment that would support urban density, the engine powering the center and sustaining the surrounding region (figure 2). To a newspaper writer, he articulated his aims: “What makes the jostling, bustling, elbow-to-elbow belly dance of life in Manhattan bearable, are small amenities like open spaces with movable chairs and food kiosks, sidewalks wide enough to accommodate crowds, stairs that are easy to climb” (Croke 1989). Having completed his basic open space analysis, Whyte now embarked on other refinements and causes. For example, he was concerned about new high-rise construction and its effect on preexisting urban plazas. Pouring over sunlight and shadow studies for a particularly offensive building, he succeeded in convincing the city government to reduce its height despite its already being under construction. Its shadow would have wrecked havoc with a nearby plaza. (See the essay by Mary V. Rickel Pelletier in this volume.) In addition, for all his progrowth talk, Whyte also appreciated how the mix and texture of buildings of different age and style enriched the urban environment, and thus he helped found the New York City Landmarks Conservancy. Finally, he was at that moment trying to figure out how to convince the federal Internal Revenue Service that scenic easements in urban areas should have favorable tax treatment. In our 1985 interview, Whyte was impressive for his mental agility, practicality, and humor. He seemed to love unraveling knotty problems. He clearly enjoyed the complexities of urban life, especially the interplay between regulation, development, and human behavior. Reflecting his consulting excursions to cities very different from New York—such as Detroit, Dallas, Minneapolis, and Tokyo—he was sensitive to geography and climate, size of city, and internal location patterns. In this last phase of his career, Whyte was a tireless advocate of healthy, busy downtowns wherever they might be located. To provide some photographs for the Planning article, Whyte suggested taking a tour of midtown Manhattan so that he could demonstrate why some urban places were successful and others not. On the appointed day, the photographer and I were to meet him at Rockefeller Center and from there we would visit half a dozen places. The day dawned bright and bitterly cold—the temperature was well below zero and the wind was whistling—but Whyte was undaunted. “The weather is perfect,” he said. “Let’s go.” The first stop, Paley Park in midtown, was deserted but still very beautiful. There he noted how the entry steps would draw people in and pointed out the composition of the trees, food concession, and movable chairs and how the waterfall Figure 2 (Top) Relaxing on Holly Whyte’s movable chairs in New York’s Bryant Park. (Bottom) Socializing in the sun, Bryant Park. (Photos by R. H. Platt.) muffled the street noise. Walking farther, he demonstrated the correct ledge width by perching on the edge of a window frame and explained that it would be lined with sitting people on a nice sunny day. Then we moved on to the IBM Plaza, a large indoor public space that was well populated that day, although someone had removed some of the chairs, to Whyte’s dismay. At Phillip Morris Plaza, another interior space, elements embodied perfection in Whyte’s estimation: the Whitney Museum had lent a whimsical sculpture, and tables and chairs filled the area. While sipping a cappuccino, he playfully conversed with one of the dancing statues. The best part of the whole morning had occurred a little earlier. While walking down Madison Avenue, Whyte pointed out a man who was walking rapidly down the west side of the street. “Just watch,” Whyte whispered. “He’s going to jaywalk to the other side on a diagonal.” Well, within seconds, that is just what the man did. Whyte knew his city and its habits. References “So let us be on with it. . . . If there ever was a time to press for precipitate, hasty, premature action, this is it.” These words are from the penultimate paragraph of *The Last Landscape*, Holly Whyte’s roundup of how, and why, we ought to preserve metropolitan open space. Not later, but now. Not after great long studies, but now. One day in the deep, dark 1960s, Stanley Tankel, the estimable chief planner at the Regional Plan Association in New York, invited Holly Whyte and me to lunch at the Harvard Club. Holly was writing his landscape book at the time and expostulating about “action,” which was his favorite word. My role in this conversation, as the young executive director of the Open Space Action Committee, of which Stanley and Holly were board members, was to shut up and listen. “Well,” says Stanley, who was feeling grouchy, “you know what planners think about that.” “Okay, what?” “We say: *Action drives out planning.*” “Exactly,” says Holly, a grin splitting his great long face. In those days, open space preservation was a very big deal. It was the means by which “the civics,” as Stanley called local activists, could mitigate the headlong rush to develop or pave over or redevelop (taller, uglier) every square inch of metropolitan land. The race for open space (including the inner-city space opened up courtesy of dynamite, wrecking balls, bulldozers, and cranes) was on, but there wasn’t enough money in the world for conservationists to purchase and set aside threatened lands in behalf of nature, human and otherwise. It was Holly’s great contribution to get the civics to understand that the lack of money was immutable, and to give them the tools to save the land anyway. Today, open space preservation has a full kit of screwdrivers, levers, and wrenches, virtually all of them—cluster development, easements, land philanthropy, tax strategies, greenways, transfer of development rights, and a whole lot more—in use because of Holly Whyte. Yet his was the work not of a professor of geography, but of a journalist: a *Fortune* magazine editor when the writers for the magazines of Time, Inc., of which *Fortune* was the classiest, set the standards for everyone else. And he was the author of *The Organization Man*, a best seller that had a profound influence, and still does, on people of a certain age, including me. In the 1960s when I became the executive director of the Open Space Action Committee (OSAC) (it was Holly who supplied not only the name of the organization but the intellectual foundation for our work), I was a refugee from Madison Avenue. I had retired from an advertising agency at the advanced age of thirty-two in substantial part because I had read *The Organization Man* and had concluded that I did not want to be one when I grew up. So by the time I arrived at OSAC in 1964, I was overjoyed to find that William H. Whyte was on the board. One time, over drinks at a bar somewhere, I told Holly that he had changed my life. He turned his long-suffering face toward me. “Don’t ever say that to me again, Little,” he said. “I am not going to be responsible for whatever dumb choices you make.” So we had another beer. I just kept my counsel and decided to adapt (steal?) Holly’s open space–saving ideas for my own work, starting with a book called *Stewardship*, which was instrumental in saving thousands of acres of open space in the New York metropolitan region. (The story of that program is told in *The Last Landscape.*) Then I used his ideas in a book called *Challenge of the Land*, which stayed in print for seventeen years through several editions. More recently, I ripped him off again in my 1989 book *Greenways for America*, finding that in fact Holly was the first to popularize this idea. The point is not that Holly invented all the land-saving gadgets of which he wrote, but that he knew how to contextualize them, how to furnish the handles so that nonspecialist readers would understand their importance. This brilliant foray into open space journalism began with conservation easements, an otherwise dry and recondite topic that Holly presented in, of all places, *Life* magazine, in those days (1959) the premier popular magazine when magazines were at the top of the mass media heap. Then came the dynamite government report in 1962. Nothing like it had been seen before; it was number 17 in the Outdoor Recreation Resources Review Commission study series entitled Open Space Action, which read like, well, *Life*. (The commission was set up by President Dwight D. Eisenhower in 1958 and led by Laurance S. Rockefeller.) Then came *Cluster Development*. And then came the whole ball of open space wax in *The Last Landscape*. Without his skills as a journalist, I doubt that the techniques Whyte proposed in these and subsequent writings would have had anywhere near the effect, for they were aimed at a nonspecialist audience, over the shoulder as it were of those who make and influence land use decisions. When an idea is presented to 6,800,000 *Life* readers—or even lesser amounts in trade books and important government reports—the message sent cannot be ignored. So today, the question is, Where are the new Hollys? Where are the land conservation writers to whom attention must be paid? We can name a few, but are they as influential as William H. Whyte? And if not, why not? Surely there ought to be a whole lot more who can carry on in the high-powered tradition of Holly Whyte, Jane Jacobs, Lewis Mumford—journalists all. I am not talking about nature writing here: there’s plenty of that, maybe too much. What Holly knew was reporting, and the importance of people and their stories so as to get ideas across and encourage others to take action. Yet this kind of writing is not just of matter of interviewing or even rhetorical skill, as important as they may be. It also has to do with vision. Maybe I am getting old and cranky or have lived too long in the wrong place (not far from Albuquerque, whose leaders, almost to a person, would like it to become Los Angeles, smog and all). One thing that Holly had, and inspired in others, however, was a sense of democratic possibility in making the good place. I have a theory that the vision of the good place that came out of 1930s progressivism, the New Deal, and the Works Progress Administration cultural programs helped give the men in foxholes and on the beaches, like Holly, a reason not only to survive, but to prevail, and to come home, and to do good work. One time, Holly made a notation in a manuscript on the egregious loss of metropolitan open space that I had sent him for review. “It is not necessary to be cynical,” he wrote. I have never forgotten that and can picture the note in my mind even now. I would submit that what’s lacking today in the journalism of open space and urban place is vision, the visionary sense of progressive possibility. For the most part, the response to dehumanized metropolitan areas and urban cores these days is limited either to despairing jeremiads or to arcane discussions of the systems to curb the excesses of developers and intellectually challenged city officials who support them. The jeremiads don’t work, and the corrective nostrums offered by planners may sound realistic—infill, adaptive reuse, intermodal transportation—but their expression, most often, is pinched and unimaginative. It fails to inspire. Surely we can do better than that. Holly’s mind was infused with pictures of a humane city and a beautiful countryside. So let us not overlook the need for visioning the good place and then acting hastily, precipitately, and prematurely to make it happen. In the end, we cannot succeed without vision, which was Holly’s great gift as a writer and as a conservationist. For without vision, said Isaiah, another good writer, the people perish. My first acquaintance with Holly Whyte goes back to the early and mid-1960s. At that time, he was overseeing and editing the multivolume Outdoor Recreation Resources Review Commission report. I was writing a book for the Urban Renewal Administration (URA), *Open Space for Urban America* (Strong 1961), to publicize and promote the URA’s newly enacted and funded program for preservation of urban open space. It was the time when open space arose to importance on the national agenda, with Lady Bird Johnson our cheerleader in the White House. Holly, then as always, was an articulate, informed, and vigorous proponent who energized a groundswell of enthusiasm. Holly and I became good friends and compatriots in the battle to publicize the availability of tools short of fee simple acquisition in the growing struggle to manage sprawl. These tools could preserve open space in private hands and private use at a cost far below that of public purchase. Holly was promoting conservation easements, speaking vigorously and often to conservation groups across the United States. I was working at the University of Pennsylvania Law School, with Jan Krasnowiecki on development of an alternative approach: compensable regulations (Strong and Krasnowiecki 1963). Thanks to the Ford Foundation, and to Gordon Harrison in particular, we enjoyed the advice of Holly as our consultant. Holly was a native of West Chester, Pennsylvania, and a committed advocate of efforts to preserve the rich farmland and scenic setting of Chester County’s Brandywine River valley. My family and I were newcomers to Chester County, settling there only in 1959, but I soon became equally dedicated to the task of protecting the Brandywine’s exceptional resources. I gathered a group of nationally renowned resource scientists, planners, and economists to develop a plan for the protection of the water resources of the Upper East Branch of Brandywine Creek through management of land use. We were committed to reliance on less than fee controls for the plan’s implementation. We gained financial and policy support from, among others, the Ford Foundation, including the appointment of Holly as one of our consultants. We spent several years of technical study, while involving local leaders in the evolving plan. Holly was often amongst us, speaking at meetings and offering advice. My admiration of his keen mind and acute sense of public sentiments grew and grew. Although the plan (Strong et al. 1968; Strong 1971) did not receive sufficient municipal support to be carried out, it did serve as a model for many subsequent efforts in the Brandywine and elsewhere. For instance, the Brandywine Conservancy now holds conservation easements on more than 35,000 acres and is a major force in the Philadelphia region for protection of urban open space. Holly and I did not work together again, but we continued to see each often, many times when speaking at conferences. Such was our final, sad get-together. Holly was to be the keynote speaker in Chicago at Rutherford Platt’s “Symposium on Sustainable Cities” in 1990. I also was on the program, and the morning of our presentations we enjoyed breakfast together. Holly had a bad cold but otherwise was, as ever, full of tales of achievements in preservation from around the country, many of which he had fostered. Then, shortly after the conference, he suffered a debilitating attack that marked the end of his wonderful, inspiring participation in a world that many of us shared. References Holly Whyte’s reach and influence were as diverse and unpredictable as the silent constituency he observed and championed. Some listened and were immediately persuaded; others nodded their heads approvingly but continued with their pre-conditioned behavior (only to be slowly converted after many observations and, in some cases, failures); and many others became disciples, joining the immediate family and sowing the seeds with actual practice. My relationship with Holly fell into this last category, based mostly on my personal need to act, not talk. In many respects, Holly’s simple, straightforward, and commonsense observations were the perfect formula and approach for me, and others like me, who were subconsciously searching for a counterbalance to the esoteric and theoretical preaching du jour. We could get our arms around these simple time-tested and approachable principles, as could our clients. Most important, they were conveyed to us in friendly constructive language—without judgment—in a structure that could be used in our collaborative pursuit of a better urban condition through the designed environment. I can easily cite those facets that attracted me to landscape architecture: natural systems, architecture, planning, art, and their combined ability to improve the quality of our lives and environment. I can also vividly remember the nagging feeling that the human condition—particularly in the urban centers—was not high on the academic agenda in design schools. Our exposure to public spaces was European parks and plazas; Central Park and its offshoots; and barren, lifeless modernist plazas. A few of us in school had already committed our professional futures to the cities. The potential to touch millions of ordinary people was obvious to me and irresistible, but nowhere in my academic experience was there mention of humanism, human behavior, sociology, or psychology. Fortunately, early years of practice in New York City introduced me to The Social Life of Urban Spaces and its author. Whyte’s teachings provided the missing link between my artistic sensibilities and the principles of public open space design and management. Over time—and with the benefit of his direct consultations and critiques—I have been able to design, observe, learn, and improve my work in ways that have miraculously transformed neighborhoods and cities. Each new park or plaza design commission follows an evolutionary process that explores new ways in which we can artistically express our time and culture, guided by Holly’s principles and gentle whispers from just over my shoulder. The Wit and Wisdom of Holly Whyte Gathered by Albert LaFarge - People sit most where there are places to sit. - Good aesthetics is good economics. - What attracts people most, it would seem, is other people. - The street is the river of life of the city; and what is a river for if not to be swum in and drunk from? - The human backside is a dimension architects seem to have forgotten. - New York is a city of skilled pedestrians. - Supply creates demand. A good new space builds its constituency—gets people into new habits, like eating outdoors; induces them to new paths. - So-called undesirables are not the problem. It is the measures taken to combat them that is the problem. . . . The best way to handle the problem of undesirables is to make a place attractive to everyone else. - Most ledges are inherently sittable, but with a little ingenuity and additional expense they can be made unsittable. - It is difficult to design a space that will not attract people. What is remarkable is how often this has been accomplished. - Walls are put up in the mistaken notion that they will make a space feel safer. Too often they make it feel isolated and gloomy. - By default street vendors have become the caterers of the city’s outdoor life. They flourish because they are servicing a demand the downtown establishment does not. - When people start to fill up a space, they do not distribute themselves evenly across it. They go where the other people are. Dense areas get denser. - Planners sometimes worry that a place might be made too attractive and thereby overcrowded. The worry should be in the opposite direction. The carrying capacity of most urban spaces is far above the use that is made of them. • Simulated cities for people who don’t like cities, it turns out, are not such a good idea after all. • Blank walls proclaim the power of the institution and the inconsequence of the individual, whom they are clearly meant to intimidate. Stand by the new FBI headquarters in Washington. You feel guilty just looking at it. • In the matter of zoning bonuses and incentives, what you do not specify you do not get. • In some American cities so much of downtown has been cleared for parking that there is now more parking than there is city. . . . One of the greatest boons of mass transit is what it makes unnecessary: the leveling of downtown for parking. • Food attracts people who attract more people. • Big buildings cast big shadows. Bigger buildings cast bigger shadows. • People in big cities walk faster than people in smaller cities. • The waterwall in Greenacre Park makes fine music. • In almost every U.S. city the bulk of the right of way is given to vehicles; the least, to people on foot. This is in inverse relationship to need. • Ninety-fourth Street is the honkingest street in town. I love it. I live here. This page intentionally left blank
THE SCOTTISH GENEALOGIST MARCH 2013 Ellen de Menteith Andrew Robertson, Part Two The Bridges of Bishopmill, Elgin Jean Stevenson and the Militia Mamie Weir – a Scot? QUARTERLY JOURNAL OF THE SCOTTISH GENEALOGY SOCIETY Vol. LX No. 1 CONTENTS Mamie Weir - a Scot? - Carolyn Emblem .................................................. 3 SAFHS Conference 2013 ................................................................................. 8 Militia Act of 1797 and Jean Stevenson - Naomi E.A. Tarrant ............... 9 The Earls of Menteith - John P. Ravilius ................................................... 12 The Bridges of Bishopmill, Elgin - Bruce B. Bishop ................................. 26 Andrew Robertson of Gladsmuir (Part 2) - Stephen W. Massil .............. 31 Scotland and the Flemish People - John W. Irvine ................................. 39 John Waldie's Journal 1826-27, Extract One - Christine Glover .......... 42 Book Reviews ................................................................................................. 45 Newbattle Parish Testimonials 1657-1671 ............................................... 47 Recent Additions - Joan Keen, Eileen Elder & Moira Stevenson ............ 48 Dates for your Diary ...................................................................................... 51 The Scottish Genealogist The Earls of Menteith: Murdoch, Earl of Menteith and the Ferrers family of Groby John P. Ravilious The history and relationships of the Earls of Menteith in the late 13th and early 14th centuries has been a source of ongoing discussion and debate, but no more so than that of their wives and daughters. Matilda, wife of Alexander, Earl of Menteith, is only known to posterity from the grant by Walter Stewart, earl of Menteith of the church of Kippen to Cambuskenneth priory: the grant was made in part ‘for the salvation of the their [Walter’s and Alexander’s] souls and that of Matilda spouse of the said [late] Alexander and for their interment’ at Cambuskenneth.¹ No record remains to provide direct evidence as to her parentage. As her grandson Alan was called the heir of Duncan, Earl of Fife in 1315, Barrow wrote in 1974 that “Earl Alexander must have married a daughter of Malcolm II earl of Fife”.² Subsequently, in 2003 it was conjectured that she was a daughter of Malise, Earl of Strathearn, based on dispensations for consanguinity between some of her descendants and those of the Earls of Strathearn.³ Bruce McAndrew has since noted heraldic evidence which places Matilda as the sister of Malise, and a daughter of Robert, Earl of Strathearn. McAndrew has shown that Alice de Menteith (fl. 1335) was likely the daughter of Murdoch, Earl of Menteith, and that the arms of her father were A chevron chequy between three mullets. This is an example of composed arms, the Menteith fess chequy being modified into a chevron chequy, reflecting the paternal coat of Murdoch’s mother Matilda of Strathearn, with the further addition of the Moravia mullets (Matilda’s mother being a daughter of Hugh de Moravia).⁴ Supporting evidence of the Strathearn ancestry of Murdoch de Menteith and his siblings has been noted in records concerning a cadet branch of the family. Robert I granted lands in Ballygillachy (Kettins parish, Forfarshire) and Methlick (Aberdeenshire) to one Malise de Menteith, a name indicative of a Strathearn connection.⁵ It was likely his son, identified as Walter de Menteith of Peterculter, who granted land near Methlick on the Ythan river to the church of St. Devenick of Methlick on 13 Jul 1364 with the consent of his son and heir John.⁶ John de Menteith died before 1393, as he is described by Laing (citing a charter of that year) as “umquhile John de Menteith, dominus de Balgillis”. John left a son William de Menteith who granted the aforementioned charter resigning the lands of “Balgillis” [presumed to be Balgillo in Tannadice parish, Forfarshire] to Patrick Blair of Balthyock in 1393. Of particular note, William de Menteith’s arms on the seal are described by Laing and MacDonald as A chevron between three birds.⁷ This is another example of composed arms, the addition of the birds indicating that John de Menteith’s wife and William’s mother was probably the heiress of the Gourlays of Balgillo. The chevron in the arms of Menteith of Methlick (later Balgillo) further evidences a Strathearn descent, and serves to support the identification of the ancestor Malise de Menteith as a younger son of Alexander, Earl of Menteith, and his wife Matilda of Strathearn. The relationship between the Earls of Menteith and Strathearn is somewhat different than first proposed. In addition to McAndrew’s findings, it is certain that Sir John Graham, Earl of Menteith (executed 1347) was not identical with John Graham of Abercorn, and was most likely a younger son of Sir David Graham of Montrose. The following chart shows the relationship of Sir John Graham and his wife Mary de Menteith, the maternal relationship between Sir James Lindsay and his wife Giles Stewart, and the more recently noted relationship between Thomas Stewart, Earl of Angus and his wife Margaret Sinclair.⁸ ![Family Tree Diagram] Alan, Alexander’s eldest son by Matilda, succeeded his father as Earl of Menteith some time before 1306. He was a participant in the coronation of Robert I at Scone on 25 March 1306, and was subsequently held forfeit by Edward I of England. He was captured and imprisoned by the English some time before 7 November 1307, and had died - probably still a prisoner - within 18 months. He had two sons who were under King Edward’s protection in 1307, when a writ of liberate was issued at Carlisle to deliver meat and fish for their sustenance. His wife Margery was then in the English camp, as John de Hastings, King Edward’s grantee of the Earldom of Menteith, had licence from the king on 13 March 1308/09 “to demise to Margery, late the wife of Alan, earl of Meneteth, for her life, the manor of Wotton”, presumably as she was then unable to receive support from her dower lands in Scotland.\(^9\) Andrew B.W. MacEwen recently advised that the identification of Alan, Earl of Menteith as both son of Earl Alexander and father of Mary de Menteith (wife of Sir John Graham) was erroneous, based on both chronology and the indenture between Robert Stewart (later 1st Duke of Albany) and Isabella, Countess of Fife explicitly stating that Alan, Earl of Menteith and Margaret Graham’s grandfather, was the beneficiary of the entail by Duncan, Earl of Fife.\(^10\) Given the identification of Matilda, Alan’s mother, as a daughter of an Earl of Strathearn, and that the aforementioned 1315 agreement provided for the reversion of the Earldom of Fife to Alan, son of Alan, Earl of Menteith, it is evident that Margery (not Matilda) was the daughter of an Earl of Fife. Duncan, Earl of Fife (father of the conflicted Earl Duncan of 1315) was born in 1262, and the issue of Alexander, Earl of Menteith and his wife Matilda were likely born in the same decade or the next.\(^11\) It appears then that Margery was most likely a younger sister of this Duncan, and that the parties concerned in the 1315 agreement – Duncan of Fife and Alan of Menteith - were first cousins. As a younger daughter of Colban, Earl of Fife and his wife Anne Durward, Margery was apparently the namesake of her maternal grandmother Margery of Scotland. \[ \text{FIG. 2} \] \[ \begin{align*} \text{Alan Durward} &= \text{Margery of Scotland} \\ \text{E of Athol} & \quad | \quad \text{E of Fife} \\ \text{Colban} &= \text{Anne Durward} \\ \text{E of Fife} & \quad | \quad \text{d. 1270} \\ \text{d. 1289} & \quad | \quad \text{d. 1306-07} \\ \text{Duncan} & \quad | \quad \text{Alan ‘II’} \\ \text{E of Fife} & \quad | \quad \text{fl. 1315} \\ \text{d. 1353} & \end{align*} \] The subsequent tenure of the earldom of Menteith was complicated due largely to the ongoing struggle with England. The second Alan [referred to as Alan II hereafter] appears to have been born ca 1290-1300. He was evidently one of the two sons of Earl Alan and Margery of Fife, the beneficiaries of a writ of liberate issued at Carlisle in 1307, certainly a minor at the time of Gilbert Malherbe’s suit seeking his wardship from the English court, dated ca. 1309-1314 by Bain.\(^12\) He died between 23 August 1315 (the date of the agreement over the Fife succession) and 6 April 1320, when his great-uncle Sir John de Menteith was ‘custos’ [guardian] of the Earldom.13 Soon after this Alan II’s daughter and heir Mary suffered the temporary grant of the Earldom to her great-uncle Murdoch, eldest surviving brother of Alan I. However, during this intervening period we find Murdoch in the English camp, the beneficiary of a curious transaction in England for which licence was granted at Leicester on 19 January 1316/7: ‘Licence for William de Ferariis to enfeoff Mordac de Meneteth of his manor of Groby, co. Leicester, and of the advowsons of the churches of the manor, held in chief: and for the latter to re-grant the same to him and Elena his wife and the heirs of their bodies, with remainder, failing such issue, to the said Mordac and his heirs. By p.s.’14 The career of Sir William de Ferrers of Groby (d. 20 March 1324/5) is fairly well documented. Born at Yoxall, co. Stafford on 30 January 1271/2, he was the son of Sir William de Ferrers of Groby, co. Leicester, sometime Constable of Scotland (d. before 20 Dec 1287), by his first wife Anne, the widowed Countess of Fife and younger daughter of Alan Durward, Earl of Athol (ca. 1232-1235) and a major participant in Scottish affairs (d. 1275).15 He was not his mother’s heir; her eldest son Duncan, Earl of Fife, held that distinction. However, he did acquire his father’s portion of the Quincy inheritance, including lands in Leuchars (Fife), in addition to which certain lands in Galloway and Ayrshire (including Drehorn) came as his grandmother Margaret de Quincy’s share of the heritage of her mother Elena, coheiress of Alan, lord of Galloway.16 Several theories have been advanced to explain the connection of Murdoch de Menteith to William de Ferrers: that which has received the widest acceptance, alleging that the wife of Murdoch was a daughter of William de Ferrers, was recently disproved by McAndrew.17 The recent correction by Douglas Richardson to the received account of Sir William de Ferrers the elder and the identification of his wife Anne as being a daughter of Alan Durward (and not of the Despenser family) provides one connection between Sir William de Ferrers the younger and the Menteith family.18 Sir William has therefore been identified as a younger half-brother of Duncan, Earl of Fife (d. 1289) and of Margery, shown above as the wife of Alan I, Earl of Menteith, and sister-in-law of Murdoch de Menteith. The Heraldic Evidence Roger Pye wrote in 1974 concerning the use of a single eagle supporter in the arms of certain Scots families, stating in part that “... all the users of the single eagle supporter are logically connected, and the solution to the problem is essentially a genealogical one...”.19 Bruce McAndrew noted more recently that the genealogical connection had been made by virtue of the identification of Margaret, wife of Sir Alexander de Abernethy, as a daughter of Alexander, Earl of Menteith. Earl Alexander's arms are typically described in part as “An eagle displayed, bearing on its breast a shield of arms.,” which was taken up by Sir Alexander de Abernethy: MacDonald described his seal as “A lion rampant debruised by a ribbon. The shield is placed in front of an eagle displayed”. The seal of Sir Alexander’s kinsman Laurence de Abernethy bore only the Abernethy arms without a supporter, indicative that the adoption of the eagle displayed was an innovation by Sir Alexander. This was the adoption of a heraldic achievement from the family of Sir Alexander de Abernethy’s wife, as noted and explained by Bruce McAndrew. An innovation in the arms of the Menteith family in fact occurred with the next generation. Alan I, Earl of Menteith, made a slight change to the appearance of the eagle on his own seal, described by Birch as “A double-headed eagle displayed charged on the breast with a shield of arms: a fess chequy, in chief a label of five points”. This is significant with regard to the identification of Elena, wife of Sir William de Ferrers. Bruce McAndrew has kindly pointed out that Sir William de Ferrers, the husband of Elena, used the arms of his father (Seven mascles, three, three, and one), with an added element: his seal shows “A double-headed eagle displayed, charged on the breast with a shield of arms [the Ferrers mascles]”. This appears to be another instance of adoption of a heraldic achievement of the wife’s family. The name Elena (frequently rendered as Ellen, or Helen) was not a rare name in medieval Scotland. The authors of the POMS project website identified 25 individuals living during the period 1093 to 1314, some of whom are known to have been related to one another. Among these was Elena, wife of John de Drummond, one of the Scots taken prisoner after the battle of Dunbar. John was imprisoned at Wisbeach castle in 1296, but came into King Edward’s peace and returned to Scotland before 19 May 1304, when King Edward issued directions to his chancellor William de Greenfield to restore Elena’s dower lands in England to them. Elena’s parentage is not stated, but Lady Edith Drummond stated in Scots Peerage (1910) that she was held by tradition to have been a daughter of Walter Stewart, Earl of Menteith. Lady Drummond noted the well-known interment of John de Drummond at Inchmahome priory in Menteith as supporting evidence of Elena’s alleged Menteith parentage, stating “this is not improbable, as only ‘founder’s kin’ could have a right to bury in such a spot”. Andrew B. W. MacEwen advised the author in 2004 that Sir John de Menteith, younger son of Earl Walter, had a daughter Elena or Ellen, wife of Sir Colin Campbell of Loch Awe, whose son Archibald or Gillespig Campbell had grants of land from his Menteith kin. Mary, daughter of Alan II and Countess of Menteith in her own right, granted him land in Kilmun, calling him “our dear and special kinsman Gillespeag Campbell”; Sir John de Menteith’s grandson John de Menteith granted lands in Knapdale on 29 November 1353 to “my faithful kinsman Gilleasbeg Cambel, lord of Lochow”. Given that Walter Stewart, Earl of Menteith most likely did have a daughter Elena, the wife of John de Drummond (d. after 1304), and his younger son Sir John de Menteith in fact had a daughter Helen or Elena, the wife of Sir Colin Campbell (d. before 1343), it is reasonable to state that the Menteiths used Helen or Elena as a typical name for their daughters in the 13th and 14th centuries. The suggestion can then be made that Sir William de Ferrers sought permission in 1316 for the grant of Groby on behalf of Murdoch de Menteith for a more personal reason than was described earlier. Sir William’s wife Elena was very likely a member of the Menteith family. Elena or Helen, the daughter of Sir John de Menteith discussed above, would appear to be a good match chronologically, but her corrected personal history as wife of Sir Colin Campbell and mother of Archibald or Gilleaspig (born ca 1312) make this virtually impossible. Sir William’s wife Elena was most likely a daughter of Alexander, Earl of Menteith, and the namesake of Alexander’s sister Elena. She then would have been a sister of Alan I, Earl of Menteith, whose heraldic achievement of a double-headed eagle displayed Sir William had adopted for his own seal. The then landless Murdoch would then not only have been connected by the marriage of William’s half-sister Margery, but would also have been the brother-in-law of Sir William de Ferrers, whom he sought to support. FIG. 3 seal of Sir William de Ferrers [Scott-Ellis, Some Feudal Lords, p.113] Sir William de Ferrers adopted the Double-headed eagle for his seal before 12 February 1300/01, as evidenced by his seal appended to the Barons’ Letter to Pope Boniface VIII, which indicates that William had married Elena de Menteith before that date. Sir William’s son Henry de Ferrers was stated to have been aged twenty-two ‘and more’ on 4 April 1325; he was therefore born sometime before 4 April 1303, but likely not much earlier. If Henry de Ferrers was born in 1302 or 1303, and Sir William de Ferrers and Elena de Menteith were married before 12 February 1300/01, it follows that Henry, and the younger sons of Sir William (Ralph and Thomas) were the issue of that marriage. That Henry was the son of Elena de Menteith can also be inferred from the terms of the licence for the re-grant of Groby by Murdach de Menteith in January 1317: Groby in fact was inherited by Henry, evidently the heir of both Sir William and Elena. There is an interesting armorial seal which may be explained by the identification of Elena as a Menteith. Sir William de Ferrers and Elena had a daughter Anne, the namesake of Sir William’s mother Anne Durward who married Sir Edward le Despenser at Groby on 20 April 1335. The seal of Anne (de Ferrers) le Despenser, appended to a document dated 1363, has in the past been taken as evidence that Anne’s mother Elena was a member of the Segrave family, as the arms in one of four roundels on the seal contain a Lion rampant. Beyond this assertion, to date the representations on the other three seals have defied conventional explanation. In particular, the left roundel contains three chevrons, which has been claimed to represent the arms of Anne de Ferrers’ mother-in-law, Eleanor de Clare. ![Seal of Anne le Despenser](Ellis, vol. I, Plate 7, p.242) In describing the heraldry documented in *The Siege of Caerlaverock*, Nicholas Harris Nicolas observed “that the placing charges on the exterior of the shield on seals approached much nearer to the subsequent system of quartering arms, and seems often to have been adopted from a similar principle, namely, of perpetuating a descent from the family of a maternal ancestor.” On the Ferrers side, the masacles (impaled) are represented by arms in the seal, as well as in the band connecting the roundels. Sir William's paternal grandmother was Margaret de Quincy, coheir of her father Roger de Quincy, Earl of Winchester, and of her mother Elena/Helen of Galloway, coheiress of her father Alan, Lord of Galloway. The lion rampant in the sinister roundel appears to represent the Lion rampant of Galloway, and the lower roundel the Cinquefoil used by the family of Margaret de Beaumont, coheiress of the honour of Leicester, and by her son Roger de Quincy. The proposal that Elena, wife of Sir William de Ferrers, was the sister of Earl Alan I of Menteith and of Murdoch then would have the Lion passant in the upper roundel as representing the family of Anne's maternal grandfather Alexander de Menteith - the Lion passant shown on his arms in the Lord Marshal's Roll, LM55. It is therefore suggested that the chevrons in the left roundel had no connection to the Clare family, but were intended to represent the arms of Anne’s maternal grandmother and Alexander’s wife, Matilda of Strathearn. Anne’s father Sir William de Ferrers inherited his landed wealth from his father, including a significant share of the Quincy and Galloway estates. Nothing is known of any lands or other property acquired through his mother Anne Durward: all of the known lands from her share of the Durward inheritance (including Coull and Kincardine O’Neil, co. Aberdeen) were inherited by her eldest son and heir, Duncan, Earl of Fife. This lack of a legacy from her Durward ancestors could explain the absence of any representation of Anne de Ferrers’ Durward ancestry in her seal. **FIG. 5** Conjectured representations in Fig. 4 <table> <thead> <tr> <th>MALE</th> <th>FEMALE</th> <th>FEMALE</th> </tr> </thead> <tbody> <tr> <td>(lion passant, for MENTEITH)</td> <td>{chevrons, for STRATHEARN}</td> <td>{Lion rampant crowned, for GALLOWAY}</td> </tr> <tr> <td>MALE</td> <td>{pierced cinquefoil, for BEAUMONT/QUINCY}</td> <td></td> </tr> </tbody> </table> That Sir William de Ferrers had a first wife before Elena, who was likely a member of the Segrave family, is discussed by Richardson. This argument also holds that Henry de Ferrers and the other issue of Sir William de Ferrers were by this first Segrave wife, based in part on a relationship between Master Thomas la Warre and Henry le Despencer, bishop of Norwich, noted in a letter written by la Warre. There was certainly a relationship between the two, but it appears to have been one generation more distant than surmised. Rather than involving the Segrave family, the kinship would have been based on the common descent of the two men from Roger de Quincy, earl of Winchester and his wife Helen, or Elena, of Galloway. The importance of this ancestry was evidently not lost on the la Warre family; so too Anne de Ferrers, mother of the Bishop of Norwich mentioned by Master Thomas la Warre as his cousin ca. 1400, made allusion to her own Quincy and Galloway ancestry in her seal. FIG. 6 The relationship between Thomas la Warre and Henry le Despencer, Bishop of Norwich Roger de Quincy = Elena of Galloway E of Winchester William de Ferrers = Margaret de Quincy E of Derby Sir William of Groby = Anne Durward Roger la Zouche = Ela Longespee Sir William De Ferrers = Elen de Menteith Alan la Zouche = Eleanor de Segrave Edward le Despenser = Anne de Ferrers Robert = Maud de Holand Henry le Despenser = John la Warre Bp of Norwich = Margaret de Holand Roger la Warre Master Thomas la Warre FIG. 7 Ellen de Menteith and her family Alan Durward = 1) Margery of Scotland = NN (not married) Colban = Anne Durward = 2) Sir William de Ferrers d. 1287 E of Fife d. 1270 Thomas Durward (illegitimate) Alexander = Matilda of Strathern [2CH] E of Menteith <E> Sir John de Menteith <DE> Elena = John de Drummond John Walter Elena Joanna = Gillespie Campbell Duncan Margery = Alan Murdoch Margaret Malise Ellen = Sir William E of Menteith E of Menteith de Menteith Methlick de Ferrers Menteith [CH] de Abernethy of Methlick d. 1325 <DE> Duncan E of Menteith E of Fife * heir of Fife, 1315 Mary = Sir John C of de Graham Walter de Menteith Anne Thomas of Methlick d. aft 13 Jul 1364 = Edward le [3CH] Despenser John de Menteith d. bef 1394 William de Menteith fl. 1393 [CH] <E> = arms/seal included An eagle displayed <DE> = arms/seal included A double-headed eagle displayed [CH] = arms/seal included A chevron [2CH] = arms/seal likely included 2 chevrons [3CH] = seal includes roundel showing 3 chevrons The Scottish Genealogist Footnotes 2. G.W.S. Barrow wrote, "Since in 1315 the then earl of Menteith (Alan son of Alan) was agreed to be heir presumptive to the earldom of Fife (Barrow, Robert Bruce, 391), it seems that Earl Alexander must have married a daughter of Malcolm II earl of Fife (1228-66)." [G. W. S. Barrow, Some East Fife documents of the twelfth and thirteenth centuries, in G. W. S. Barrow, ed., The Scottish Tradition: Essays in honor of Ronald Gordon Cant (Edinburgh: Scottish Academic Press, 1974), p.40]. 3. J. Ravilious, The Ancestry of Mary Abernethy: a Menteith Connection?, soc.genealogy.medieval, 5 Dec 2003. Two dispensations in particular indicate a mutual Strathern descent. There was a mandate of Pope John XXII dated at Avignon, 1 May 1334, for a postnuptial dispensation for "John de Gram, knight, and Mary de Me[n]tet" as they were related within the fourth degree of consanguinity [W. H. Bliss, ed., Calendar of Entries in the Papal Registers Relating to Great Britain and Ireland (London: for the Public Record Office, 1895), Papal Letters Vol. II, p.411]. The second was a mandate of Pope Clement VI dated at Avignon on 11 April 1346 for "James de Lindesay, knight, and the noblewoman Egidia Steward" ["Jacobo de Lundesay Militi, et Dilecte in Christo Filio Nobili Mulieri Egidie Steward" due to their being related in the third and fourth degrees on their fathers' side, and in the fourth degree on their mothers' side ["in tertio et quarto ex parte partum, et in quarto &c. ex parte matrum vestrorum consanguinitatis gradibus"]. Andrew Stuart, Genealogical History of the Stewarts (London: A. Strahan et al., 1798), p.434). 6. The grant was made by "Walterus de Menthet dominus de Petmacaldor" together "de consilio et assensu Johannis filii mei et heredis". Cosmo Innes, ed., Registram Episcopus Aberdonensis (Edinburgh: Spalding Club, 1845), vol. I, pp.112-3. 8. Sir William de St. Clair, sheriff of Edinburgh, died some time before 7 April 1299, when his widow Amicia had a letter of protection from Edward I of England [Bain, Calendar of Documents relating to Scotland 1272-1307, vol. II (Edinburgh, 1884), p.280, no. 1104]. She is shown by various authors as Lucia, daughter of Robert, Earl of Strathearn. While primary evidence for this name and parentage is lacking, it is known that Sir William and his wife had a daughter Annabella, a name closely associated with the earls of Strathearn [Fraser, Memorials of the Family of Wemyss of Wemyss, vol. II (Edinburgh, 1888), pp.5-6, no. 3; cf. Paul, Scots Peerage vol. VIII, pp.478-9]. Further support of a Strathearn origin for Sir William's wife is found in the dispensation for the marriage of his great-granddaughter, Margaret, to Thomas Stewart, Earl of Angus, the mandate for which was granted at Villeneuve on 3 June 1353 [W. H. Bliss and C. Johnson, eds., Calendar of Entries in the Papal Registers Relating to Great Britain and Ireland (London: for the Public Record Office, 1897), Papal Letters Vol. III, p. 512]. The mandate states that Margaret and Thomas were 'related in the fourth degree of kindred': if Thomas' great-grandmother Matilda of Strathearn was the sister of Margaret Sinclair's great-grandmother, this would have been the exact relationship necessitating the dispensation. 9. Alan was held forfeit and his earldom granted to John de Hastings by order of Edward I dated at West Denton, 28 Sept 1306 [Bain, ibid., vol. II, pp.491-2]. Order of Edward I "as to Aleyin late earl of Menteth...and other adherents of Robert de Brus, who have come to the King's peace to be in law, and prisons to which they have been sent" dated ca. 7 November 1307 [Bain, ibid., vol. II, p.495, no. 1849]. Dated at Carlisle, "Writ of liberate to the two sons of the Earl of Menteth, and the son of the Earl of Stratherne, of a quarter of an ox, etc." [Bain, ibid., vol. II, p.523, no. 1971, dated by Bain as "[1307]"] Licence by King Edward II to John de Hastings dated at Westminster, 1 March 1308/09 [Calendar of the Patent Rolls, 2 Edw II, mem. 10, p.108]. "Margaria Menteeth" was still one of two tenants holding Wootton, Northants. of Sir John de Hastings in 1316 [Inquisitions and Assessments Relating to Feudal Aids, vol. IV, p.27]. 10 Private communication by Andrew B.W. MacEwen, 5 November 2004. That Earl Alan had a son and heir (Alan 'II') was attested well before 1315, as early in the reign of Edward II (ca. 1309-1314 acc. to Joseph Bain) Gilbert Malherbe sought "a grant of the ward and marriage of the late Earl of Menteith's son and heir, or the keeping of Jedburgh Castle" as compensation for the loss of a prior grant [Bain, ibid., vol. III, p.78, no. 410 (cites 'Tower Miscellaneous Rolls, No. 459'). Alan, Earl of Menteith (Alan 'II') was referred to as both the Alan who had the earldom of Fife entailed upon him, and the grandfather of Margaret Graham, in the indenture between Robert Stewart, Earl of Menteith and Isabella, Countess of Fife (dated at Perth, 30 Mar 1371): "...tam per talliacionem factam per bone memorie dominum Duncanum comitem de Fyff, patrem dictae dominis comites, dominum quondam Alano comiti de Menteith, auo domine Margarete, sponse dicti domini Roberti nunc comitis elusdem..." [Fraser, The Red Book of Menteith (Edinburgh, 1880), vol. II, p.252, no. 34]. 11 'Alano de Menetethe, filio comitis de Menetethe' and his brother Peter had the gift of horses from King Edward I of England for use in fighting for the King in France, order dated at Winchester, 21 Aug 1296 [Joseph Stevenson, Documents illustrative of the history of Scotland from the death of King Alexander the Third to the Accession of Robert Bruce (Edinburgh: H. M. General Register House, 1870), Vol. II, p.139]. It seems reasonable to assume Peter de Menteith was of age (21 or more), if not already knighted, when provision was being made for him to fight on horseback in August 1296, and so he was likely born in or before 1275: his brother Alan would have been somewhat older. The identification of Margery, wife of Earl Alan I, as a daughter of Colban, Earl of Fife was noted by Bruce McAndrew in 2009 [Bruce McAndrew, The Identity of Countess Alice of Menteith (fl 1335-1339): part 1, The Scottish Genealogist, Vol. LVI No. 4 (December 2009), p.194]. 13 Barrow, Robert the Bruce and the Community of the Realm of Scotland (2005), p.361. His uncle Sir John de Menteith was identified as 'Johannes de Meneteth custos comitatis de Menteeth' when he assented to the Declaration of Arbroath on 6 April 1320 [Fordun, Scotichronicon (Edinburgh: Robert Fleming, 1759), vol. II, p.275]. 15 Complete Peerage, ibid. With regard to the inheritance of Galloway (formerly de Morville) lands in Drehorn, co. Ayr, there is record of the (English) account for the period 20 November 1302-20 November 1304 "for 55s. 4d. from the farms of Sir Alan de la Souche's and Sir William de Ferrers' lands in Drehorn (Dregenere), taken in the K.'s hand for their not doing service in his army" [Bain, ibid., vol. II, p.425, no. 1608. Cf. p.304, no. 1186 as to the restoration "to William de Ferrars [of] his hereditary lands in Galloway, taken in the K.'s hands when he was there", royal order dated at Netleyham, 2 Feb 1300/01]. 22 The seal of Laurence de Abernethy (dated ca. 1320) is given in MacDonald, *ibid.*, p.1, no. 4. 23 McAndrew, *ibid.* 25 It is also interesting that the Double-headed eagle was also taken up by Earl Alan's uncle Sir John de Menteith at about the same time [MacDonald, *ibid.*, p.247, no. 1950]. 27 English and Scottish heraldry of the period was not without other examples of the use of a double-headed eagle. Besides the relations of the Earls of Menteith, Birch identified 8 individuals who were contemporaneous with Sir William de Ferrers of Groby, or nearly so, among whom John de Grymesby, parson of West Keal, Lincolnshire appears to have the highest social rank [Birch, *Catalogue of Seals in the Department of Manuscripts in the British Museum* (London: Longmans and Co., 1894), Vol. 3, p.46, no. 10,318. The seals of the other 6 English armigers can be found on pp.11, 12, 138, 217, 463 and 585. The seal of the Scots armiger, William de Upsettington, is found in Birch, *ibid.*, vol. 4, p.598, no. 17,017.] None of these individuals has been identified as being of sufficient rank to have Sir William de Ferrers marry a sister or another near kinswoman. It is therefore deemed improbable that such a union would have occurred, or that Sir William de Ferrers would have inherited the heraldic achievement of such a family as part of his own seal. 28 People of Medieval Scotland 1093-1314, URL [http://www.pcms.ac.uk](http://www.pcms.ac.uk). Three individuals of this name in the database can be readily shown as near relations: Helen (or Elena) de Moreville, Helen de Galloway (her granddaughter) and Helen la Zouche (daughter of Helen of Galloway). 33 *Calendar of Inquisitions Post Mortem* (Hereford: printed for His Majesty's Stationery Office, 1910), vol. VI, pp.376-7, no. 603. The Leicestershire inquisition was dated "Thursday after Palm Sunday, 18 Edward II" [i.e., 4 April 1325]. The Northamptonshire inquisition was held on 13 April. 34 Richardson, *Magna Carta Ancestry*, *ibid.*, vol. II, p.72, 296. Widow of Edward le Despenser, knight. A shield of arms: quarterly, in the second and third quarters a fret, over all a bend (DESPENSER) impaling four mascles. Within a cusped circle, surrounded by a band of pointed tracery broken by four roundels of arms containing (above) a sleeping lion (below) a pierced cinquefoil, (L) three chevrons, (R) a lion rampant crowned. S: .AN[N].LE[DESP]EN[SER] As mentioned in the text of this article, the "band of pointed tracery" is actually composed of twelve mascles, three between every pair of roundels. These may have been intended to represent the three mascles missing from Anne's paternal arms in the seal. The identification of Sir William de Ferrers' wife as a Segrave is one of long standing [cf. Complete Peerage, vol. V, pp.343-4; note also the grant of the lands of William de Ferrers when a minor to Nicholas de Segrave junior for a fine of 100 marks, dated 18 May 1288 (Cal. Patent Rolls (1281-1282), p.295]. Douglas Richardson has kindly pointed out the heraldic evidence in the windows of Baddeley Clinton as supporting this, as the arms shown in the window for this William de Ferrers are shown as Ferrers impaling Segrave [Rev. Henry Norris, Baddeley Clinton: its Manor, Church and Hall (London:Art and Book Company, 1897), p.64]. The arms depicted in the windows are reasonably accurate, but are understood to have been a creation of the 16th or 17th century [Norris, ibid., p. 63]. Possibly due in part to the gap in time between the marriages themselves and their commemoration in the windows of Baddeley Clinton, it is important to note that the arms depicted provide occasionally misleading genealogical evidence. In particular, the arms of William de Ferrers' father are shown impaling not the arms of his mother, Anne Durward, but rather those of his step-mother Eleanor de Lovaine. There are other arms which could have been depicted which are clearly not if a complete heraldic presentation had been intended (e.g., the arms of Sibyl Marshal, one of the heiresses of the well-known William Marshal and the first wife of William de Ferrers's grandfather William, Earl of Derby, are not shown). That William de Ferrers may have married a Segrave lady as his first wife seems quite likely, but the Baddeley Clinton windows should not be taken as proof of this alliance, let alone evidence that this individual was the mother of one or more of William de Ferrers' children. Richardson, ibid., vol. II, p.72. McAndrew, Scotland's Historic Heraldry, p.51. The chevrons in the left roundel, if representing Strathearn, ought to number 2 and not 3, as observed by Bruce McAndrew and Douglas Richardson. Given the revised ancestry assigned to Anne de Ferrers in this article, this appears to be either an error or artistic licence on the part of the seal's artisan. 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Emanuele FADDA, « Saussure on individual linguistic knowledge: a non-nativist notion of instinct ? » Pour consulter le programme complet de l’atelier de Claire Forel, Genoveva Puskas, Thomas Robert et Giuseppe Cosenza, **Saussure-Chomsky: converging and diverging** : Saussure on individual linguistic knowledge: a non-nativist notion of instinct? Emanuele Fadda Università degli Studi di Catania lelefadda@gmail.com No linguist in the 20th century underwent as many ideologically-driven readings as Saussure. John E. Joseph Anzi procede per si lungo cammino, che sembra star. Giacomo Leopardi ABSTRACT The mainstream account of Saussurean theory describes it as completely objective, taking language (la langue) as a social, abstract object having no relation at all with the speaker/listener and her knowledge. Generative Linguistics, instead, claims to adopt the attitude of taking into account the speaker’s (although it is an ideal speaker) knowledge, and even states that every biological individual as such has language in her mind. In spite of this (almost) unquestioned opinion, a close reading of Saussure’s texts shows hints of a clear focus on the linguistic knowledge and conscience of the speaker. Namely, the notion of sentiment de la langue, which can be found widely throughout Saussure’s works and notes, represents a form of very weak conscience. Closely related to this notion, it is also possible to find some occurrences of instinct, or rather of instinctivement (“instinctively”). Using these words, Saussure refers to linguistic (semi-)automatic activity, which is not, indeed, operated by native mechanisms, but works just like native instincts. This shows how Saussure, just as Chomsky, considers (semi-)automatic mechanisms which guide linguistic behavior as a pivotal object for linguistics; but, unlike Chomsky, he thinks that this kind of linguistic mechanism is not related to a native device. This kind of conception opens a new perspective about language, where “natural” fades into “cultural”, and vice versa. KEYWORDS Chomsky, Saussure, Conscience, Instinct, Morphology John Joseph’s study on Saussure’s readings by Bloomfield and Chomsky opens with a claim that every historian of linguistic thought should adopt as a peculiar form of gnòthi seautòn, namely: The history of linguistics is largely a history of misreadings, of failed communication between authors and readers, exacerbated by the illusion that communication has successfully occurred. (…) Whether semi-intentional or genuinely accidental, these misreadings are rarely neutral. Texts are not processed by empty brains, but by minds already stocked with set ideas, a priori categories, prototypes — and, perhaps most importantly, agenda. In other words, misreadings are usually ideologically determined. This is not a slur against the field of linguistics or its history. (Joseph 2002: 133) In this paper, I would like to avoid (as far possible) these kinds of misreading. In my attempt to do justice to Saussure, I will not present his views as a form of Cognitivism avant la lettre, but rather as a theory where the focus on linguistic systems in their independency from individual speakers does not involve neglecting the speaking subject, whose consciousness and skills are the only raison d’être of language as a system. In order to show this, I will first take an overview of Chomsky’s positioning in relation to Saussure (and its changing through time), and then focus on some Saussurean terms and notions (with a clear psychological taste) which are usually neglected, namely: sentiment, consciousness (conscience), will, and instinct. The latter of these notions (which should be out of place in a Saussurean frame, as it is usually presented) will be my starting point for developing some conclusive remarks in a semiotic fashion. 1. A look backwards: a quasi-Saussurean Chomsky? The risk of misreading Joseph signalled is particularly dangerous when we approach the issue of the relation between Saussure and Chomsky. On one side, Saussure (or rather the CGL) has become a flag1 waved by an army whose gathering together he could not forecast (nor discuss or oppose); on the other, Chomsky’s positioning within the linguistic community in the early stages of his career was somewhat fluctuating. As Joseph clearly shows, Chomsky was guided by his agenda in his choice of enemies and ancestors, and his pars destruens and pars construens changed accordingly. If we take Joseph’s article as our guide, we can individuate four phases (Joseph 2002: 147 ff.), which he names (maybe a little be roughly, but substantially righteously): 1. 1963: The Saussurean 2. 1962-64: Reaching further back (Humboldt & Descartes) 3. 1965-79: The Anti-saussurean 4. 1986-1990: the Neo-saussurean? I will just say some words on the first of these phases, but first I would like to add a phase 0. In the account Cognitivists use to give of their history, Chomsky’s review of Verbal behaviour is considered as the actual birth of Cognitivism, raising on the ashes of Behaviourism and restoring the rights of the Human Mind. Chomsky’s arguments are well known2, and one of them is the following: The fact that all normal children acquire essentially comparable grammars of great complexity with remarkable rapidity suggests that human beings are somehow specially designed to do this, with data-handling or ‘hypothesis-formulating’ ability of unknown character and complexity. (Chomsky 1959: 57) --- 1 I speak of a flag, because the weapons are often different (e.g. Jakobsonian, Hjelmslevian, or Greimasian). 2 Or they are supposed to be so: see Joseph (2002: 179 ff.). In these words, we find the embryo of the (so-called) “Plato’s problem” (see Chomsky 1986, 1988, 2000). At this stage, however, Chomsky is just reproaching Skinner for the fact that the empirical data he is basing his theory on are not collected by experiments on human beings. As to Chomsky, human beings show faculties and skills that are clearly absent in other animals, and that is what needs to be explained. At that time, the anti-behaviourist fight meets Saussure’s proposals (or some of them), so that “the agenda behind Chomsky (1963) is to highlight every possible correlation between the CLG and Chomsky’s own work.” (Joseph 2002: 148). Namely, Chomsky comes across some Saussurean terms and issues which are out of the focus of mainstream Structuralism, and which help him to shape “the speaker's linguistic intuition, his knowledge of the language” (Chomsky 1963: 329), so that Saussure is seen in an anti-bloomfieldian (and anti-behaviorist) fashion. Even, at least once, Chomsky explicitly refers to Saussure’s notion of consciousness, namely in 1964’s edition of Current Issues: In evaluating a particular generative grammar, we ask whether the information that it gives us about a language is correct, that is, whether it describes correctly the linguistic intuition of the speaker (Saussure’s "conscience des sujets parlants", which to him, as to Sapir, provides the ultimate test of adequacy for a linguistic description). (Chomsky 1964: 26) This is consistent with what he says in Aspects of the Theory of Syntax, where he explains “intuitive knowledge” as lack of awareness by the speaker about the rules, or a lack of accuracy in describing them. Yet, the reference to Saussure disappears. By a generative grammar I mean simply a system of rules that in some explicit and well-defined way assigns structural descriptions to sentences. Obviously, every speaker of a language has mastered and internalized a generative grammar that expresses his knowledge of his language. This is not to say that he is aware of the rules of the grammar or even that he can become aware of them, or that his statements about his intuitive knowledge of the language are necessarily accurate. (Chomsky 1965: 8). In this phase, we still do not find the focus on nativism that we will find later (see Chomsky 1988, 2000, 2002; Pinker 1994), and Chomsky focuses on the pars destruens, i.e. the very idea of the speaker’s intuitive knowledge. I will not follow the other phases, but I will add some elements to fill the frame of a Saussurean account of the speaking subject as the source of langue (not to be seen in a simplistic nativist fashion). 2. Saussure’s notion of ‘sentiment de la langue’ --- The first notion we have to approach is the *sentiment de la langue*. The main sources we have to understand Saussure’s notion are three: - Note on morphology (Godel 1957 N 7: 40 ff.; *ELG*: 180 ff. = Engl. trans.: 122 ff.) - First Course of General linguistics (1907/1996) - (Half-)course in Latin & Greek morphology (1910, unpublished) The best way to present the notion is probably to start from the third one. We don’t have access to Saussure’s autograph notes, but the three testimonies we have (Riedlinger, Constantin, Patois) are rather concordant. Godel quotes Riedlinger’s version as early as 1957. Nous n’avons pas l’intention de définir la morphologie, ni de parcourir le champ qu’elle occupe. Nous ne voulons fixer notre attention qu’à une opération qu’on fait en morphologie, qui est d’analyser le mot, de le décomposer en plusieurs parties. [...] Mais il faut se demander dans quel cas cette analyse est légitime, juste ou non. Eh bien il n’y a pas d’autre mesure que celle-ci: si elle coïncide avec le sentiment des sujets parlants. Dans la mesure où (je ne dis pas consciemment, instinctivement) les sujets parlants ressentiront des unités de la langue, nous aurons une raison pour les établir. (Riedlinger: Saussure 1910, Ms. 1986/15; quoted in Godel 1957: 210) Sans définir ce que c’est la morphologie, je me bornerai à un point, à une opération qu’on fait en morphologie. Nous étudions l’analyse morphologique des mots au point de vue du principe. [...] Il faut se demander dans quels cas cette division est légitime. On le reconnaîtra à ce qu’elle coïncide ou pas avec le sentiment des sujets parlants eux-mêmes. Dans la mesure où l’on peut affirmer non pas consciemment mais instinctivement dans les autres faits de langue dans la même mesure on aura une justification. (Constantin: Saussure 1910, Ms. 3972, 25) Analyser le mot en plusieurs parties est un but de la morphologie. [...] à quoi reconnaîtra-on qu’une analyse est juste ou non ? À ce qu’elle coïncide ou non avec le sentiment des sujets parlants. Dans la mesure où on peut affirmer qu’au moins instinctivement ils ressentiront des idées différentes. (Patois: Saussure 1910, Ms 3972, C1) We can summarise the common content of these quotes in these four points: 1. to define Morphology, we must turn to its basic mechanism: the *division* of words 2. the only way to prove this division is correct, is to remark the coincidence with the division made by the speaking subjects 3. The speaking subjects make this division referring to their *sentiment* 4. *sentiment* is a weak, instinct-like form of consciousness --- 4 I will always refer to this notion in French, in order to preserve the peculiar ambiguity (the speaker’s sentiment about her language vs. the sentiment whose subject is the language itself) it shows (see Fadda 2013: § 5, 59 ff. 2017b: 14 ff.). 5 But the most important text is N7. Unfortunately, its dating is uncertain. 6 The 1910 Course in Latin and Greek Grammar starts with *Phonétique*. After some months, Saussure joins a Morphological part, teaching the two in different days of the week. The Phonetica part (or rather, Riedlinger’s notebooks) has been presented and discussed by Marie-José Beguelin (1981). Someone could think that we are facing some technical problems concerning the reconstruction of ancient languages, which do not affect the core of linguistic theory. Actually, to base such a judgment on the current use of ‘morphology’ would be deceptive, since for Saussure Morphology is substantially equivalent to Synchronic Linguistics\(^7\). So, this consciousness (i.e. the *sentiment de la langue*) is the one Chomsky referred to as the pivot of Linguistic research. 2.1.1. Sentiment as conscience As Godel\(^8\) and Engler already remarked, Saussure uses ‘sentiment’ as a quasi-synonym of ‘conscience’. Indeed, it is a synonymy whose contours have to be carefully traced, as they involve a relation of mutual defining with other terms. Engler (1968), in particular, gives no meaning for the entry ‘sentiment’ in his lexicon, but he merely refers to other items, namely ‘concret’, ‘conscience’, ‘réalité’. As to those terms, we can remark that: - *conscience* occurs considerably more often - *sentiment* is relatively more frequent when the subject is morphology - *concret* and *réalité* refer to the fact that the *sentiment* of the speaking subject is to be seen as the *immediate datum* for the linguist (which is not performance/parole) This bond linking sentiment, conscience, and linguistic reality is particularly evident in a fundamental passage belonging to N7. *Critérium* : Ce qui est réel, c’est ce dont les sujets parlants ont conscience à un degré quelconque ; tout ce dont ils ont conscience et rien que *ce* dont ils peuvent avoir conscience.” (N7 = *ELG*: 183; Engl. trans.: 125) Here, the very word of ‘criterium’ shows the affinity with Chomsky’s perspective. The immediate problem Saussure is facing is obviously different: Saussure needs to find the actual decomposing of a word at a given point of time (i.e. not an anachronical one)\(^9\). But the solution is the same: the judgment of the speaking subject (and therefore her consciousness, however inexplicit it may be) is the one and only lighting guide for the linguist. 2.2. Degrees of consciousness and degrees of will In the second 1891 inaugural conference, Saussure distinguishes two degrees (or rather three) of linguistic consciousness. --- \(^7\) See e.g. Saussure (*ELG*: 21 ff.; Engl. trans.: 6 ff.). At § 6b, Saussure distinguishes a “strict sense” of morphology (whereas the broad sense is supposed to be Synchronic Linguistics). \(^8\) As to Godel, I found his use of an affective or emotional lexicon in referring to linguistic sentiment particularly interesting: see Godel (1957: 42 “secret”; 157 “intime”). \(^9\) This concept is easy to explain by an example: no contemporary Italian speaker would imagine one could split *però* in *per* + *hoc*, or *ancora* in *hanc* + *horam*, as a Latin (or a cultivated man in XIIIth century) did. Il y a d'une part le changement phonétique et d'autre part le changement appelé de divers noms, dont aucun n'est excellent, mais dont le plus usité est le changement analogique. Nous verrons immédiatement pourquoi. On peut opposer sous beaucoup de points de vue différents ces deux grands facteurs de renouvellement linguistique, en disant par exemple que le premier représente le côté physiologique et physique de la parole tandis que le second répond au côté psychologique et mental du même acte -, que le premier est inconscient, tandis que le second est conscient, toujours en se rappelant que la notion de conscience est éminemment relative, de sorte qu'il ne s'agit que de deux degrés de conscience dont le plus élevé est encore de l'inconscience pure comparé au degré de réflexion qui accompagne la plupart de nos actes. (Saussure 1891(I) = ELG: 159; Engl. trans.: 106) If we go back to the distinction introduced by Ernst Tugendhat (1979), we should remark that Self-consciousness (Selbstbewusstein), here, is not separable from self-determination (Selbstbestimmung), the two being the facets of a same phenomenon. Linguistic will, as linguistic consciousness, is substantially unconscious. Les faits linguistiques peuvent-ils passer pour être le résultat d'actes de notre volonté? Telle est donc la question. La science du langage, actuelle, y répond affirmativement. Seulement il faut ajouter aussitôt qu'il y a beaucoup de degrés connus, comme nous savons, dans la volonté consciente ou inconsciente ; or, de tous les actes qu'on pourrait mettre en parallèle, l'acte linguistique, si je puis le nommer ainsi, a ce caractère [d'être] le moins réfléchi, le moins prémédité, en même temps que le plus impersonnel de tous. Il y a là une différence de degré, qui va si loin qu'elle a longtemps donné l'illusion d'une différence essentielle, mais qui n'est en réalité qu'une différence de degrés. (Saussure 1891(II) = ELG: 150; Engl. trans.: 99) This “paradox of the will” (a kind of free will problem in a linguistic fashion) brings us to the heart of the issue. What Saussure calls instinct is just this: consciousness escaping from consciousness, and will escaping from will. 3. Saussure’s notion of instinct Once reconstructed (at least partially: we may add the psychic/psychological couple. See Fadda 2018b: § 2.3) the constellation of Saussurean terms concerning the relation between language knowledge and linguistic activity, we are ready to approach our specific subject: the role of instinct. In Saussure’s text, the word seems to have two main significations: 1. It is a way of denoting the Faculté du langage. 2. It is a way of referring to semi-automatic operations related with epilinguistic knowledge. In the first case, ‘instinct’ is sometimes associated with a call to nature; in the second, we often find the adverb (“instinctivement”) rather that the noun. Let’s see some examples. I will present three for the first signification (numbered by lowercase letters) and five for the second (numbered by capital letters). The examples for instinct/1 are drawn from the introductive part of *CGL* and from the beginning of the first Geneva conference in 1891. In both cases (even if separated by many years), it is a matter of determining the place of linguistics among sciences, and the place of *langue* (or *langues*) within the vast complex of linguistic phenomena. (a) La langue, au contraire, est un tout en soi et un principe de classification. Dès que nous lui donnons la première place parmi les faits de langage, nous introduisons un ordre naturel dans un ensemble qui ne se prête à aucune autre classification. A ce principe de classification on pourrait objecter que l'exercice du langage repose sur une faculté que nous tenons de la nature, tandis que la langue est une chose acquise et conventionnelle, qui devrait être subordonnée à l'instinct naturel au lieu d'avoir le pas sur lui. (*CGL*: 25; Engl. trans.: 9) (b) Je vous dirai, Messieurs, qu'on a tout refusé à notre pauvre espèce humaine comme caractère distinctif vis-à-vis des autres espèces animales, tout, et absolument tout, y compris l'instinct d'industrie, y compris la religiosité, la moralité, le jugement et la raison, tout, excepté le langage. (Saussure 1891(1) = *ELG*: 145; Engl. trans.: 95) (c) Mais, réciproquement, l'étude de ces langues existantes se condamnerait à rester presque stérile, à rester en tout cas dépourvue à la fois de méthode et de tout principe directeur, si elle ne tendait constamment à venir illustrer le problème général du langage, si elle ne cherchait à dégager de chaque fait particulier qu'elle observe le sens et le profit net qui en résultent pour notre connaissance des opérations possibles de l'instinct humain appliqué à la langue. (Saussure 1891(1) = *ELG*: 146 Engl. trans.: 96) In the first case, in the very act of posing *langue* as the pivotal object for linguistics, Saussure admits that no *langue* could rise out of the exercise of the faculty of language. In the second, he defends the role of language (in the same “Cartesian” fashion as Chomsky does) as the ultimate mark for humanity. In the third, he remarks that the study of general aspects of language and the study of particular (i.e. specific to each *langue*) ones are complementary to one another and mutually necessary. Now, let’s see the quotes for instinct/2. They are drawn from *CGL*, and from other texts concerning morphology and analogy. Only the scholars who deal with the *CGL* as if it was a treatise in Epistemology (where Linguistics is but a pretext) will not see the continuity among these texts. Actually, for Saussure, Linguistics is its “technical” aspects. Every example pertaining to every single language is – so to say – charged with theory. (A) A la suite de cette altération du mot, la position de l'accent n'a plus été la même vis-à-vis de l'ensemble ; dès lors les sujets parlants, conscients de ce nouveau rapport, ont mis instinctivement l’accent sur la dernière syllabe, même dans les mots d'emprunt transmis par l'écriture (*facile, consul, ticket, burgrave, etc.*). (CLG: 123; Engl. trans.: 86) (B) *Wetter* est instinctivement rapproché de *Wittern*, parce qu'on est habitué à voir *e* alterner avec *i*. À plus forte raison, dès que les sujets parlants sentent qu'une opposition phonique est réglée par une loi générale, cette correspondance habituelle s'impose à leur attention et contribue à resserrer le lien grammatical plutôt qu'à le relâcher. (CLG: 220; Engl. trans.: 160) (C) Après avoir constaté que deux idiomes diffèrent, on est amené instinctivement à y découvrir des analogies. C'est là une tendance naturelle des sujets parlants. (CLG: 262; Engl. trans.: 192) (D) Quand des formes nouvelles surgissent, tout se passe, nous venons de le voir, par décomposition des formes existantes et recomposition d'autres formes au moyen de matériaux fournis par les premières. On décompose instinctivement Belessi en Bel-essi et on applique le résultat à composer Qeressi. (N7 = ELG: 191; Engl. trans.: 131) (E) Il est merveilleux de voir comment, de quelque façon que les événements diachroniques viennent troubler, l'instinct linguistique s'arrange à en tirer le meilleur parti pour une [ ]. (ELG: 266; Engl. trans.: 191) If we have a closer look at these quotes, we find that, while (A), (B) and (D) can be ascribed to instinct/2, in (C) and (E) it is just impossible to draw a sharp line between the two significations: actually, they are both present. In (C) we find “natural trend”, in (E) “linguistic instinct”. Instinct/1 (instinct as faculty) is then shown to be the aptitude or disposition to use instinct/2 (instinct as epilinguistic consciousness), without any possibility (if not in a formal sense) to draw a line dividing an acquired component from a native one. The “language instinct” is all of that, and it is the only possible starting point. 4. Some conclusions (in a semiotic frame) The overlapping between instinct/1 and instinct/2 is not just explicable with the (correct) remark that the latter is not conceivable without the former. We must also add that Saussure, unlike Chomsky and others, see consciousness as a continuum, where it is difficult to draw sharp lines of demarcation. So, the interaction between Faculté du langage and the learning and mastering of a given langue gives rise to different kind and degrees of consciousness, from sentiment (epilinguistic morphological knowledge)10 to wholly mechanical reactions. From a Saussurean point of view, drawing a sharp line between native and acquired features of language is not the first goal for linguistic to reach. This kind of view, founded on a double paradox – an unconscious consciousness that also is an unwilling will – opens a general perspective on human nature. Whereas Chomskian notions (LAD, UG, e-language) are designed to dig (and progressively deepen) a ditch between language (or rather its core or kernel) and the rest of human cognitive and practical skills, the Saussurean view is susceptible to enlargement within a vast semiotic perspective. Regarding this, it is worth noting that also Peirce and Wittgenstein employ a notion of instinct that clash with Cognitivist views (where ‘instinctive’ means ‘native’, as opposed to ‘acquired’ or ‘learned by experience’). Indeed, Peirce, Saussure and Wittgenstein use the term in the same way: ‘instinct’ is all that works as an instinct, i.e. the reaction taking place in certain cases, 10 Related to analogical change in the second inaugural conference. See ELG: 159 f.; Engl. trans.: 106. triggered in a semi-automatic, immediate way, and without any reflection – whatever its origin\textsuperscript{11}. This faculty/necessity of arbitrary habits and rules (in Peirce’s and Wittgenstein’s sense) is not limited to language, but is a general character of our access to the human community. Together with language \textit{stricto sensu} (whether we see it as e-language or as \textit{langue}), we can find other human behavioural universals, both embodied and arbitrary (i.e. submitted to a judgment which is both immediate and irrevocable: right or wrong, within or without), like posture and proxemics, and so on. All these forms of life (to use a Wittgensteinian term) show cognitive immediacy and normative immediacy. I call ‘cognitive immediacy’ the fact to know surely, but without reasons, where even the simple possibility of doubt is excluded. Under this category, we can place the grammatical competence (or epilingualistic knowledge) next to social cognition (or at least to a large part of it): I know that “people behave like that”, and expect from others from my group to know it. I call ‘normative immediacy’ the fact to constantly behave in some ways (acknowledged within the group) in certain situations, \textit{without thinking} and following a \textit{rule} that is also a \textit{duty}. What I called above “instinct/2” is the core of this area. We could maybe say that it is the more natural of cultural human skills. But this definition actually has no sense in a (post-)saussurean semiotic framing, where the completion of nature is culture, and the completion of culture is nature. \textsuperscript{11} I discussed some reasons for this comparison in Fadda (2017b, chap. 3). References —, 1916 (1922², 1931³. From 1972 and until 2016, supported by Tulio De Mauro’s Introduction and Commentary = CLG. Cours de linguistique générale, publié par Ch. Bally et A. Sechehaye avec la collaboration de A. Riedlinger [Engl. trans.: Course in General Linguistics. New York: Columbia UP].
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Abstract—To achieve the full flexibility of industrial robots, in addition to the mechanical flexibility, it is necessary to achieve the flexibility in control. Precise automatic calibration of these robots manipulators is essential precondition for achieving this goal. Possibilities and limitations of stereo vision system implementation for automatic calibration of manipulators are presented in this paper. Furthermore, a practical solution for the problem of corresponding points using an area based algorithm is given. Analysis has been conducted of how the marker positioning on the manipulator end-effector influences the shape of the cost function. Choice of window size relative to marker size which provides the best reliability for corresponding area determination is proposed. Results of practical realization, which confirms conducted analysis and reliability of proposed calibration procedure, are presented. Index Terms—Camera calibration, Computer vision, Modular reconfigurable robot, Robot calibration. I. INTRODUCTION A high level of positioning accuracy is an essential requirement in a wide range of industrial robots applications. This accuracy is affected by geometric factors (geometrical parameters accuracy) and non-geometric factors (gear backlashes, encoder resolution, flexibility of links, thermal effects, etc.). The error due to geometric factors accounted for 90% of the total error. A common approach is to calibrate the current geometric parameters and treat the non-geometric factors as a randomly distributed error. The calibration procedure is very important for robot programming using CAD systems where the simulated robot must reflect accuracy the real robot. During a manipulator control system design, and periodically in the course of task performing, manipulator geometry calibration is required [1]. Vision systems have developed significantly over the last ten years and now have become standard automation components. They represent qualitative bounce in the area of metrology and sensing because they provide us with a remarkable amount of information about our surroundings, without direct physical contact [2]. At the same time, vision systems are the most complex sensors [3]. Calibration of cameras is necessary first step in vision system using. Camera calibration is the process of determining the internal camera (geometric and optical) characteristics and the 3D position and orientation of the camera frame relative to a world coordinate system [2], [4]. There are a number of techniques which only requires the camera to observe a planar pattern(s) shown at a few different orientations. Precise set points are placed on the calibration plain. Calibration process is automatically performed based on the correspondence between the positions of calibration points and the positions of their images [5], [6]. If the camera calibration is performed then for every scene point in a world coordinate system it is possible to determine the position of its image point in image plain. This transformation is called perspective transformation. Inverse perspective transformation is very important for computer vision application in industrial automation. This transformation examines the problem of how to identify the point position in a world coordinate system based on the position of its image point for different camera positions or for several cameras at the same time. Inverse perspective transformation and advances in processing and image analysis have a wide range of applications in industrial automation, and allow companies to achieve previously impossible levels of efficiency and productivity [7]. Effective co-operation in the computer aided manufacturing depends on the recognition and perception of typical production environments as well as on the understanding of tasks in their context. Vision systems are the basis for scene analysis and interpretation, both in time and 3D space. Measurement of the dimensions of objects and parts in many industrial fields is very important, as the quality of the product depends especially on the reliability and precision of each object part. The use of vision-based metrology allows calculating a set of 3D point coordinates and/or estimate the dimension and pose of a known object. They enable industrial robots to perform different and complex tasks reliably and accurately [8]. II. ROBOT CALIBRATION A. Manipulator Geometry Modeling The first step of manipulator calibration is concerned with a mathematical formulation that results in model which gives relation between the geometric parameters, the joint variables and end-effector position. Many researchers have been looking for the suitable kinematic models for robot calibration, since Richard Paul’s book [9]. The most popular among them is the Denavit-Hartenberg (D-H) method. For this reason we will use this notation. Prior description kinematic model let us define the basic coordinate systems as follows (Fig. 1.): \[ O_B X_B Y_B Z_B \] - base coordinate system of the manipulator \[ O_E X_E Y_E Z_E \] - end-effector (tool) coordinate system of the manipulator (we denote the origin \( O_E \) as the endpoint of the robot) \[ O_i X_i Y_i Z_i \] (i=1, n) - coordinate system fixed to the i\textsuperscript{th} link \[ (O_nX_nY_nZ_n) \] - coordinate system fixed to the terminal link of the manipulator. The original D-H representation of a rigid link depends on geometric parameters. Four parameters \( a,d,\alpha \) and \( \theta \) denote manipulator link length, link offset, joint twist and joint angle, respectively. Composite 4x4 homogenous transformation matrix \( A_{i,i-1} \), known as the D-H transformation matrix for adjacent coordinate system \( i \) and \( i-1 \), is: \[ A_{i-1,i} = \begin{bmatrix} \cos \theta_i & -\cos \alpha_i \sin \theta_i & \sin \alpha_i \sin \theta_i & a_i \cos \theta_i \\ \sin \theta_i & \cos \alpha_i \cos \theta_i & -\sin \alpha_i \cos \theta_i & a_i \sin \theta_i \\ 0 & \sin \alpha_i & \cos \alpha_i & d_i \\ 0 & 0 & 0 & 1 \end{bmatrix} \] The homogenous matrix \( A_{B,i} \) which specifies the location of the i\textsuperscript{th} coordinate system with respect to the base coordinate system is the chain product of successive coordinate transformation matrices \( A_{i,i-1} \), and expressed as: \[ A_{B,i} = A_{B,i} A_{i,2} \ldots A_{i,1} \] Particularly, for \( i=n \) we have \( A_{B,n} \) matrix which specifies the position and orientation of the end-effector of the manipulator with respect to the base coordinate system. Matrix \( A_{B,n} \) is a function of the \( 4n \) geometrical parameters which are constant for constant robot geometry, and \( n \) joint coordinates that change their value when manipulator moves. Moreover, a robot is not intended to perform a single operation at the workcell, it has interchangeable different tools. In order to facilitate the programming of the task, it is more practical to have transformation matrix defining the tool coordinate system with respect to the terminal link coordinate system \( A_{w,E} \). Thus, the transformation matrix \( A_{w,E} \) can be written as: \[ A_{w,E} = A_{w,B} A_{B,n} A_{n,E} \] Since the world coordinate system can be chosen arbitrarily by the user, six parameters are needed to locate the robot base relative to the world coordinate system. From independence to some manipulator parameters it follows that consecutive coordinate systems are represented at most by four independent parameters. Since the end-effector coordinate system can be defined arbitrarily with respect to the terminal link coordinate system \( (O_nX_nY_nZ_n) \), six parameters are needed to define the matrix \( A_{n,E} \). If we extend the robot notation to the definition of the end-effector coordinate system, it follows that the end-effector coordinate system introduces four independent parameters. For more details the reader can refer to [1]. With above mentioned equations (1), (2), (3) dependence between joint coordinates and geometrical parameters, and endpoint location of the tool can be written as: \[ x = f(q, g^\theta) \] where \( x,q,g^\theta \) denotes end-effector position vector expressed in the world coordinate system, vector of the joint variables, and vector of the geometric parameters, respectively. Dimension of the vector \( x \) is 6 if measurement can be made on the location and orientation of the end-effector. However, the most frequently only a location of the endpoint is measured, and therefore dimension of a vector \( x \) is 3. Dimension of the vector \( q \) is equivalent to the number of DOF for manipulator. Dimension of the vector \( g^\theta \) is at most \( 4n+6 \). **B. Geometric Parameters Estimation Based on the Differential Model** The calibration of the geometric parameters is based on estimating the parameters minimizing the difference between a function of the real robot variables and corresponding mathematical model. Many authors [10]–[13] presented open-loop methods that estimate the kinematic parameters of manipulators performing on the basis of joint coordinates and the Cartesian coordinates of the end-effector measurements. The joint encoders outputs readings are joint coordinates. It is assumed that there is a measuring device that can sense the position (sometime orientation) of an end-effector Cartesian coordinates. A mobile closed kinematic chain method has been proposed that obviates the need for pose measurement by forming a manipulator into a mobile closed kinematic chain [14], [15]. Self motion of the mobile closed chain places manipulator in a number of configurations and the kinematic parameters are determined from the joint position readings alone. The calibration using the end-effector coordinates (open-loop method) is the most popular one. The model represented by equation (4) is nonlinear in \( g^\theta \), and we must linearize it in order to apply linear estimators. The differential model provides the differential variation of the location of the end-effector as a function of the differential variation of the geometric parameters. The function to be minimized is the difference between the measured \(x\) and calculated end-effector location \(\tilde{x}\). Let \(\Delta x=x-x_0\), and \(\Delta g=g-g_0\) be the pose error vector of end-effector and geometric parameter error vector, respectively \((g-\text{vector of geometric parameters estimation})\). From equation (4), the calibration model can be represented by the linear differential equation \[ \Delta x = J_\delta \Delta g = x-x_0, \] (5) where: - \(g\) is the \((p \times 1)\) vector of geometric parameters estimation - \(\Delta x\) is the \((r \times 1)\) pose error vector of end-effector - \(\Delta g = g-g_0\) is the geometric parameter error vector - \(J_\delta\) is the \((r \times p)\) sensitivity matrix relating the variation of the endpoint position with respect to the geometric parameters variation (calibration Jacobian matrix) [10], [13]. To estimate \(\Delta g\) we apply equation (5) for a number of manipulator configurations. It gives the system of equations: \[ \Delta X = \Phi \Delta g + E \] (6) where: \[ \Delta X = \begin{bmatrix} \Delta x^1 \\ \vdots \\ \Delta x^r \end{bmatrix}, \quad \Phi = \begin{bmatrix} J_\delta^1(q^1, g) \\ \vdots \\ J_\delta^r(q^r, g) \end{bmatrix}, \] (7) and \(E\) is the error vector which includes the effect of unmodeled non-geometric parameters: \[ E = \begin{bmatrix} e^1 \\ e^2 \\ \vdots \\ e^r \end{bmatrix}. \] (8) Equation (6) can be used to estimate iteratively the geometric parameters. This equation is solved to get the least-squares error solution to the current parameters estimate. The least-squares solution can be obtained from: \[ \Delta g = (\Phi^T \Phi)^{-1} \Phi^T \Delta X. \] (9) At each iteration, geometric parameters are updated by adding \(\Delta g\) to the current value of \(g\): \[ g = g + \Delta g. \] (10) By solving equations (9) and (10) alternately, the procedure is iterated until the \(\Delta g\) approaches zero. Calibration a manipulator is an identification process, and hence, one should take a careful look at the identifiability of the model parameters [10], [14]. A general method to determine these parameters have been proposed in [14]. Determination of the identifiable (base) geometric parameters is based on the rank of the matrix \(\Phi\). Some parameters of manipulator related to the locked passive joints may become unidentifiable in the calibration algorithm due to the mobility constraints. It reduces number of identifiable parameters in general for the closed-loop kinematic chain approach, compared with open-loop case. As the measurement process is generally time consuming, the goal is to use set of manipulator configurations that use limited number of optimum points on the parameters estimation. Furthermore, goal is to minimize the effect of noise on the parameters estimation. The condition number of the matrix \(\Phi\) gives a good estimate of the persistent excitation [1]. Therefore, much work was led on finding the so-called optimal excitation. The task of selecting the optimum manipulator configurations to be used during the calibration is discussed and solutions are proposed in [14]–[16]. It is worth noting that most of geometric calibration methods give an acceptable condition number using random configurations. The paper [17] presents an updating algorithm to reduce the complexity of computing and observability index for kinematic calibration of robots. An active calibration algorithm is developed to include an updating algorithm in the pose selection process. ### III. COMPUTER VISION #### A. Camera Model This section describes the camera model. Fig. 2 illustrates the basic geometry of the camera model. The camera performs transformation from the 3D projective space to the 2D projective space. The projection is carried by an optical ray originating (or reflected) from a scene point \(P\). The optical ray passes through the optical center \(O_c\) and hits the image plane at the point \(p\). Prior describing the perspective transformation, and camera model, let us define the basic coordinate systems. The coordinate frames are defined as follows: - \(O, X_w, Y_w, Z_w\) - world coordinate system (fixed reference system), where \(O_w\) represents the principal point. The world coordinate system is assigned in any convenient location. - \(O, X_c, Y_c, Z_c\) - camera centered coordinate system, where \(O_c\) represents the principal point on the optical center of the camera. The camera coordinate system is the reference system used for camera calibration, with the \(Z_c\) axis the same as the optical axis. - \(O, X_i, Y_i, Z_i\) - image coordinate system, where \(O_i\) represents the intersection of the image plane with the optical axis. \(X_i, Y_i\) plane is parallel to \(X_c, Y_c\) plane. Let \((x_o, y_o, z_o)\) are the 3D coordinates of the object point \(P\) in the 3D world coordinate system, and \((u, v)\) position of the corresponding pixel in the digitized image. A projection of the point \(P\) to the image point \(p\) may be represented by a 3x4 ![Fig. 2. The basic geometry of the camera model.](image-url) projection matrix (or camera matrix) $M$ [2], [5]: $$p = K[R \ T]P = MP .$$ \hspace{1cm} (11) Matrix: $$K = \begin{bmatrix} \alpha & 0 & u_0 \\ 0 & \beta & v_0 \\ 0 & 0 & 1 \end{bmatrix}$$ \hspace{1cm} (12) is called the internal (intrinsic) camera transformation matrix. Parameters $\alpha$, $\beta$, $u_0$ and $v_0$ are so called intrinsic distortion-free camera parameters. $R$ and $T$, a 3x3 orthogonal matrix representing the camera’s orientation and a translation vector representing its position, are given by: $$R = \begin{bmatrix} r_{11} & r_{12} & r_{13} \\ r_{21} & r_{22} & r_{23} \\ r_{31} & r_{32} & r_{33} \end{bmatrix}, \quad T = \begin{bmatrix} t_x \\ t_y \\ t_z \end{bmatrix},$$ \hspace{1cm} (13) respectively. The parameters $r_{11}$, $r_{12}$, $r_{13}$ are external (extrinsic) parameters and represent the camera’s position referred to the world coordinate system. Fig. 3. illustrates the effect of radial distortion illustrated on a grid. Projection in an ideal imaging system is governed by the pin-hole model. Real optical system suffers from a number types of distortion. The first one is caused by real lens spherical surfaces and manifests itself by radial position error. Radial distortion causes an inward or outward displacement of a given image point from its ideal (distortion free) location. This type of distortion is mainly caused by flawed radial curvature curve of the lens elements. A negative radial displacement (a point is imaged at a distance from the principle point that is smaller than predicted by the distortion free model) of the image point is referred to as barrel distortion. A positive radial displacement (a point is imaged at a distance from point that is larger than the predicted by the distortion free model) of the image point is referred to as pin-cushion distortion. The displacement is increasing with distance from the optical axis. This type of distortion is strictly symmetric about the optical axis. Fig. 3. illustrates the effect of radial distortion. ![Fig. 3. Effect of radial distortion illustrated on a grid.](image) The radial distortion of a perfectly centered lens is usually modeled using the equations: $$\Delta x = x_i(k_1r^2 + k_2r^4 + ...),$$ \hspace{1cm} (14) $$\Delta y = y_i(k_1r^2 + k_2r^4 + ...),$$ \hspace{1cm} (15) where $r$ is the radial distance from the principal point of the image plane, and $k_1,k_2,...$ are coefficients of radial distortion. Only even powers of the distance $r$ from the principal point occur, and typically only the first, or the first and the second terms in the power series are retained. The calibration of systems also suffer from tangential distortion, which is at right angle to the vector from the center of the image. That type of distortion is generally caused by improper lens and camera assembly. Like radial distortion, tangential distortion grows with distance from the center of distortion and can be represented by equations: $$\Delta x = -y_i(l_1r^2 + l_2r^4 + ...),$$ \hspace{1cm} (16) $$\Delta y = x_i(l_1r^2 + l_2r^4 + ...).$$ \hspace{1cm} (17) Fig.4 illustrates the effect of tangential distortion. The reader is referred to [2]–[4] for more elaborated and more complicated lens models. Note that one can express the distorted image coordinates as a power series using undistorted image coordinates as variables, or one can express undistorted image coordinates as a power series in the distorted image coordinates. The $r$ in the above equations can be either based on actual image coordinates or distortion-free coordinates. Bearing in mind the radial and tangential distortion, correspondence between distortion-free and distorted pixels image coordinates can be expressed by: $$x_d = x_i + \Delta x_i + \Delta x_i,$$ \hspace{1cm} (18) $$y_d = y_i + \Delta y_i + \Delta y_i.$$ \hspace{1cm} (19) The parameters representing distortion of an image are: $k_1,k_2,..., l_1,l_2,...$. The distortion tends to be more noticeable with wide-angle lenses than telephoto lenses. Electro-optical systems typically have larger distortions than optical systems made of glass. B. Camera Calibration Camera calibration is considered as an important issue in computer vision applications. With the increasing need for higher accuracy measurement in computer vision, if has also attracted research effort in this subject. Task of camera calibration is to compute the camera projection matrix $M$ from a set of image-scene point correspondences. By correspondences it means a set $(p_i,P_i)_{i=1}^n$ where $p_i$ is a homogeneous vector representing image point and $P_i$ is a homogeneous vector representing scene point, at the $i^{th}$ step. Equation (11) gives an important result: the projection of a point $P$ to an image point $p$ by a camera is given by a linear mapping (in homogeneous coordinates): $$p = MP .$$ \hspace{1cm} (20) The matrix $M$ is non-square and thus the mapping is many-to-one. All scene points on a ray project to a single image point. To compute $M$, it have to be solved the system of homogeneous linear equations $$s_ip_i = MP_i ,$$ \hspace{1cm} (21) where $s_i$ are scale factors. Camera calibration is performed by observing a calibration object whose geometry in 3D space is known with very good precision. The calibration object usually consists of two or three planes orthogonal to each other. These approaches require an expensive calibration apparatus. Accurate planar targets are easier to make and maintain than three-dimensional targets. There is a number of techniques which only requires the camera to observe a planar pattern(s) shown at a few different orientation (Fig. 5). The calibration points are created by impressing a template of black squares (usually chess-board pattern) or dots on top of white planar surface (steel or even a hard book cover [5]). The corners of the squares are treated as a calibration points. Because the corners are always rounded, it is recommended to measure the coordinate of a number of points along the edges of the square away from the corners, and then extrapolate the edges to obtain position of the corners which lie on the intersection of adjacent edges. Due to the high accuracy performance requirement for camera calibration, a sub-pixel estimator is desirable. It is a procedure that attempts to estimate the value of an attribute in the image to greater precision than that normally considered attainable within restrictions of the discretization. Since the CCD camera has relatively low resolutions, interest in a sub-pixel method arises when one applies CCD-based image systems to the computer integrated manufacturing [6]. Camera calibration entails solving for a large number of calibration parameters, resulting in the large scale nonlinear search. The efficient way of avoiding this large scale nonlinear search is to use two-stage technique, described in [2]. The methods of this type in the first stage use a closed-form solution for most of the calibration parameters, and in the second stage iterative solution for the other parameters. In [4] a two-stage approach was adopted with some modification. In the first step, the calibration parameters are estimated using a closed-form solution based on a distortion-free camera model. In the second step, the parameters estimated in the first step are improved iteratively through a nonlinear optimization, taking into account camera distortion. Since the algorithm that computes a closed-form solution is no iterative, it is fast, and solution is generally guaranteed. In the first step, only points near the optical axis are used. Consequently, the closed-form solution isn’t affected very much by distortion and is good enough to be used as an initial guess for further optimization. If an approximate solution is given as an initial guess, the number of iterations can be significantly reduced, and the globally optimal solution can be reliably reached. C. Stereo Vision Calibration of one camera and knowledge of the coordinates of one image point allows us to determine a ray in space uniquely (back-projection of point). Given a homogeneous image point \( p_i \), we want to find its original point \( P \) from the working space. This original point \( P \) is not given uniquely, but all points on a scene ray from image point \( p_i \). Here, we will consider how to compute 3D scene point \( P \) from projections \( p_i \) in the several cameras, or projections \( p_i \) in one camera at different positions (different images are denoted by superscript \( i \)). Assume that \( m \) views are available, so that we have to solve linear system \[ s_i p_i = M p_i, \quad i = 1, \ldots, m. \] This approach is known as triangulation (it can be interpreted in terms of similar triangles). Geometrically, it is a process of finding the common intersection of \( m \) rays given by back-projection of the image points by the cameras. In the reality, image points \( p_i \) are corrupted by noise, and the rays will not intersect and the system would have no solution. We might compute \( P \) as the scene point closest to all of the skew rays. If two calibrated cameras observe the same scene point \( P \), its 3D coordinates can be computed as the intersection of two of such rays. The epipolar geometry is a basis of a system with two cameras (principle of stereo vision). It is illustrated on Fig. 6. Obviously, the ray the projection of the ray in one camera into the other camera. The base line is the line joining the camera centers $O_1^c$ and $O_2^c$. The baseline intersects the image planes in the epipoles $e_1$ and $e_2$. Alternatively, an epipole is the image of the optical center of one camera in the other camera. Any scene point $P$ and the two corresponding rays from optical centers $O_1^c$ and $O_2^c$ define an epipolar plane. This plane intersects the image plane in the epipolar line. It means, an epipolar line is the projection of the ray in one camera into the other camera. Obviously, the ray $O_i^cP$ represents all possible positions of $P$ for the first image and is seen as the epipolar line $l_2$ in the second image. The point $p_2$ in the second image that corresponds to $p_1$ must thus lie on the epipolar line in the second image $l_2$, and reverse. The fact that the positions of two corresponding image points are not arbitrary is known as the epipolar constraint. This is a very important statement for the stereo vision. The epipolar constraint reduces the dimensionality of the search space for a correspondence between $p_1$ and $p_2$ in the second image from 2D to 1D. A special relative position of the stereo cameras is called rectified configuration. In this case image planes coincide and line $O_1^cO_2^c$ is parallel to them, as shown in Fig. 7. The epipoles $e_1$ and $e_2$ go to infinity, and epipolar lines coincide with image rows, as a consequence. For the rectified configuration, if the internal calibration parameters of both cameras are equal, it implies that corresponding points can be sought in 1D space along image rows (epipolar lines). The optical axes are parallel, which leads to the notion of disparity that is often used in stereo vision literature. Top view of two cameras stereo configuration with parallel optical axes is shown in Fig. 8. World coordinate system is parallel to cameras coordinate systems. The principal point $O_w$ of the world coordinate system is assigned on the midway on the baseline. The coordinate $z_w$ of point $P$ represents its distance from the cameras ($z_w = 0$), and can be calculated from the disparity $d = u_1 - u_2$. Values $u_1, u_2$ are measured at the same height (same rows of images). Noting that: $$ \begin{align*} u_1 &= \frac{x_w + B}{2}, & u_2 &= \frac{x_w - B}{2}, f &= \frac{z_w}{z_w}, \end{align*} $$ we have: $$ z_w = \frac{Bf}{d}. $$ The remaining two coordinates of the 3D point $P$ can be calculated from equations: $$ x_w = \frac{-B(u_1 + u_2)}{2d}, \quad y = \frac{Bv}{d}. $$ The position of the point $P$ in the 3D scene can be calculated from the disparity $d$. It is a question, how the same point can be found in two images if the same scene is observed from two different viewpoints. The solution of this correspondence problem is a key step in any stereo vision. Automatic solution of the correspondence problem is under extensive exploration. Until now there is not solution in general case. The inherent ambiguity of the correspondence problem can in practical cases be reduced using several constrains. A vast list of references about this task can be found in the [3]. The geometric transformation that changes a general cameras configuration with non-parallel epipolar lines to the parallel ones is called image rectification. More deep explanation about computing the image rectification can be found out in [3]. **IV. ROBOT CALIBRATION USING COMPUTER VISION** Measurement of robot manipulator end-effector pose (i.e., position and orientation) in the reference coordinate system is unquestionably the most critical step towards a successful open-loop robot calibration. A variety of measurement techniques ranging from coordinate measuring machines, proximity measuring systems, theodolites, and laser tracking interferometer systems to inexpensive customized fixtures have been employed for calibration tasks. These systems are very expensive, tedious to use or with low working volume [12], [18], [19]. In general, the measurement system should be accurate, inexpensive and should be operated automatically. The goal is to minimize the calibration time and the robot unavailability. To overcome the above limitations, advances in robot calibration allow the start using a computer vision to calibrate a robot. Compared to those mechanical measuring devices, the camera system is low cost, fast, automated, user-friendly, non-invasive and can provide high accuracy [20]. There are two types of setups for vision-based robot pose measurement. The first one is to fix cameras in the robot environment so that the cameras can see a calibration fixture mounted on the robot and while the robot changes its configuration. The second typical setup is to mount a camera or a pair of cameras on the end-effector of the robot manipulator. The stationary camera configuration requires the use of stereo system placed at fixed location. It is not possible compute 3D scene point \( P \) position from only one projection \( p \), on the camera plane. The Stereo system has to be placed in location that maintains necessary field-of-view overlap. The proper camera position needs to be selected empirically. The stereo system must be calibrated before manipulator calibration. The manipulator is placed in a number of configurations. From pair of images the location (position and orientation) of the calibration board is computed for every configuration (Fig. 9.). At the each configuration, geometric parameters are updated by adding \( \Delta g \) (calculated in accordance with equation (9)) to the current value of \( g \) [21]. The position of a marker (end-effector) is determined on the basis of pairs of images from stereo camera system [22]. Any point of the marker can be assumed as referent point of end-effector of the manipulator. For this reason, hereinafter a term „marker” is considered as a whole, rather than a one specified point. In this case the main problem is the automatic detection of corresponding points. The corresponding points are represented by a set of marker points on both images. This paper uses algorithm based on the most similar intensity area correlation. The algorithm assumes that more pixels have similar intensity (color). Therefore, correlation of two pixels does not provide sufficient information because of the existence of more similar candidates. Thus, correlation of more adjacent pixels which are forming the window of \( hxw \) pixels is determined. When stereo system with parallel optical axes is used, the epipolar lines of both cameras lie on the same height on both images, as shown on Fig. 10. If it is enough to measure only the end-effector pose (usually tool’s tip) for robot calibration, then it is not necessary to use a calibration plate. In that case it is enough to place a marker on the end-effector of the manipulator. Tests were conducted with square markers. In this way the calibration of the manipulators, from the viewpoint of practical implementation, is simplified. Also, this is an important prerequisite for increasing the flexibility of the manipulators, because in the case of automatically interchangeable tools, a marker can be placed on the end-effector of the manipulator. Then, for any change of tools, by tracking the position of marker it is possible to accomplish the recalibration of the manipulator. The goal is to minimize the calibration time and the robot unavailability. The stationary camera configuration requires the use of stereo system placed at fixed location. It is not possible compute 3D scene point \( P \) position from only one projection \( p \), on the camera plane. The Stereo system has to be placed in location that maintains necessary field-of-view overlap. The proper camera position needs to be selected empirically. The stereo system must be calibrated before manipulator calibration. The manipulator is placed in a number of configurations. From pair of images the location (position and orientation) of the calibration board is computed for every configuration (Fig. 9.). At the each configuration, geometric parameters are updated by adding \( \Delta g \) (calculated in accordance with equation (9)) to the current value of \( g \) [21]. The algorithm principle is as follows. Window of \( hxw \) pixels is formed. The window central pixel represents the referent point on one of two images from stereo system (Ex. left image). This window is used as referent area to be searched on the second image (i.e. right image). On the second image the same size window is observed on the same height as on the first image. By changing window disparity \( d \) the second window is sliding along \( u \) axe. Measure of two windows intensity likelihood, i.e. cost function, is calculated as Sum of Squared Differences of all pixels intensities in both windows: \[ C(u,v,d) = \sum_{[h,w]} \left[ Im_L(u+h,v+w) - Im_R(u+h+d,v+w) \right]^2 \] The value of disparity \( d \), for which is obtained minimal value of cost function, gives the position of window which is the best correlated with the reference window. Therefore, the corresponding windows are on the same height on both images, but shifted along \( u \) axe for: \[ disparity(u,v) = \min C(u,v,d) \] For the purpose of calibration, stereo system with two standard web color cameras was used. The algorithm was tested with color marker placed on the end-effector of a modular Robix manipulator. Adopted window size is 5x5 pixels. Fig. 11. and Fig. 12. present images from left and right cameras, respectively. A detail of marker found on the second image is shown on Fig. 12. Fig. 13. shows graphical representation of cost function for disparity change along epipolar line, from minimum to maximum value. It is obvious, as it shown on Fig. 13, that a reliable method of determining the corresponding points is obtained by using marker and ![Fig. 9. A manipulator calibration using stationary camera configuration.](image-url) selected cost function. Selected cost function has a pronounced global minimum. For successfully finding of corresponding points, choice of window size is crucial. In the classical problem of correspondence, if the window size is too small, it increases probability of occurrence of a large number of candidates for correspondence. This increases probability of wrong selection of corresponding points. On the other hand, if the window size is too large, there is a possibility for error because of a constant value of disparity within the window. Therefore, there is no single recommendation for the best window size. In special cases, even an adaptive window size is suggested, but such algorithms are generally very complex, compute demanding and not widely accepted in practice. In accordance with previous demonstration, windows size will depend on the size of the marker when it is necessary to determine markers correspondence on two images. Marker is an area with nearly constant intensity (color). By adopting a window smaller than the marker, all the windows, which are contained in the marker, will be detected as candidates. Thus, there will be no single solution for the problem of correspondence. In another case, by adopting a window size larger than the size of marker, by increasing a size of window the value of cost function will not depend on the compliance of marker points. Value of the cost function will be influenced by compliance of region points out of marker. Therefore, it is reasonable assumption that the cost function will have less pronounced global minimum. Further augmentation of window size (relative to marker size) may produce error in correspondence estimation. Points surrounding marker will have significant influence on window correlation compared to marker points. Based on this analysis, it is concluded that the best results are achieved by adopting window size approximately equal to marker size. Assumptions about the window size effects (relative to marker size) on the reliability of the correspondence procedure have been tested in several cases. Window size has been altered for different marker sizes. Diagrams of minimum values change of cost functions with change of window size, for three different sizes of markers, are illustrated on Fig. 14. In order to compare results, values of cost functions, shown on diagrams, are divided with number of pixels that belongs to window. In this way, the cost functions represent the average inconsistency for every pixel of two windows. The first marker (Fig. 14.a) is the size of 11x11 pixels, the second marker (Fig. 14.b) is the size of 21x21 pixels and a third marker (Fig. 14.c) is the size of 37x37 pixels. The illustrations confirm that the best results are achieved by adopting that window size is equal to marker size. ![Graphical representation of cost function for disparity change along epipolar line.](image1) **Fig. 14b.** Graphical representation of cost function for disparity change along epipolar line. ![Graphical representation of cost function for disparity change along epipolar line.](image2) **Fig. 14c.** Graphical representation of cost function for disparity change along epipolar line. V. CONCLUSION An overview of new features for improving the calibration of industrial manipulators using visual systems is presented in this paper. The focus is on the stereo system with parallel optical axes. The practical aspects of using the algorithm based on area correlation are particularly analyzed. In order to increase the reliability of the corresponding areas determination the next is proposed: set the marker on end-effector of manipulator, choose the window size equal to marker size and scale cost function with total number of pixels for each window. Conducted experiments and shown illustrations confirm that presented calibration method allows efficient and reliable manipulator calibration in standard conditions. REFERENCES
Historicizing and Theorizing Pre-Narrative Figures—Who is Uncle Sam? Lukas R. A. Wilde, Shane Denson Narrative, Volume 30, Number 2, May 2022, pp. 152-168 (Article) Published by The Ohio State University Press DOI: https://doi.org/10.1353/nar.2022.0008 For additional information about this article https://muse.jhu.edu/article/855321 For content related to this article https://muse.jhu.edu/related_content?type=article&id=855321 Historicizing and Theorizing Pre-Narrative Figures—Who is Uncle Sam? ABSTRACT: This contribution examines Uncle Sam’s development during the nineteenth century as an interesting case study for transmedial character theory, an increasingly common approach to the study of fictional characters. However, as Scolari, Bertetti, and Freeman have argued, “older forms of transmedia franchises were constructed on character sharing rather than on the logics of a particular world” (17). Characters were and still are in many cases the nodal points and intersections of various processes discussed as media convergence, yet the distinctions between “actual” characters and related terms such as “cultural icons” (Brooker) or “serial figures” (Denson and Mayer) remain somewhat contested and often hard to draw in practice. This contribution addresses these issues by investigating the nineteenth-century emergence and transformation of Uncle Sam as a recognizable figure within political cartoons. Without any overarching creative authority or any consistent “storyworld” to speak of, these cartoons lend themselves to recontextualizations by any artist able to uphold a recognizable iconography. In media-historical terms, political cartoons that did not merely comment upon actually existing public persons but instead developed their own inventory of allegorical figures are an important link between earlier, more “static” pictorial personifications of—and symbols for—countries and ideas and the later emergence of serial characters within comic books and other narrative media. KEYWORDS: American popular culture, caricature, cartoons, iconography, political symbols, political cartoons, symbolism, Thomas Nast, transmedial characters, seriality, Uncle Sam Lukas R. A. Wilde is a Postdoctoral Research Associate at the University of Tuebingen’s Department of Media Studies. His dissertation Im Reich der Figuren [Empire of Characters] was awarded the Roland-Faelske-Award 2018 for the best dissertation in Comics and Animation Studies and the GIB Dissertation Award 2021 of the Society for the Interdisciplinary Study of Pictures. Shane Denson is Associate Professor of Film & Media Studies and, by Courtesy, of German Studies and of Communication at Stanford University. He is the author of Postnaturalism: Frankenstein, Film, and the Anthropotechnical Interface (2014) and Discorrelated Images (2020). Who is Uncle Sam? 19th Century Pre-Narrative Figures and the Emergence of Transmedia Character Culture Lukas R. A. Wilde OVER 150 YEARS OLD, the figure known as “Uncle Sam” is very much alive today. When two planes hit the World Trade Center on September 11, 2001, dozens of cartoonists immediately turned to the old symbolic personification of the United States Government to express their sadness, confusion, or anger (see Lamb; McWilliams). When George W. Bush called for justice in his televised speech on September 17, earlier pictorial cyphers of a weeping Lady Liberty had already given way to the masculine Uncle Sam whose gleaming eyes were as much a reflection of the burning towers as of the blazing fury within his vengeful mind (see Wilde, “Falling,” for more detail). Who is Uncle Sam, however, and what is he represented to be? Are there any stable character traits throughout his countless portrayals? Even in the nineteenth century he was depicted as Shakespeare’s Oberon and Hamlet, as Samson, Santa Claus, Quixote, Moses, Wotan, and Hercules—as well as in countless other roles and functions fitting the depicted context respectively (Ketchum 133). There were female versions employed as icons for the suffrage movement in 1909 (Palczewski). Artists from other countries changed his appearances and traits even further by replacing the stars with dollar signs or by putting a slaveholder’s whip in his hands (Fischer 323). His “core identity” seems to impose boundaries and limitations for artists merely on a thematic or symbolic level: Uncle Sam will never be a “common man,” but always some figure of authority, and he will never be a symbol for Russia or other countries, but always for the United States—or, more precisely, the US government. Using James Phelan’s influential character model comprised of a “synthetic” level (the materials and structures of representation), a “mimetic” level (an actual or imagined individual), and a “thematic” level (characters as representations of larger groups or of ideas or concepts), the last dimension is strongly foregrounded for Sam, while the mimetic remains undeveloped and can be entirely inconsistent from one depiction to the next. Pictures of Uncle Sam, in other words, are more ideographs than icons, denoting not any fictional or non-fictional individual, but abstract ideas that vary across contexts. For these reasons, Uncle Sam is an early example of a “pre-narrative character” or a figure without a story. Taking up a terminological distinction by Shane Denson and Ruth Mayer, it might be more appropriate to speak of “serial figures” (serielle Figuren) instead of “series characters” (Serienfiguren), the former circulating (and “existing”) outside of specific narrative contexts (Denson and Mayer). In the last couple of years such pre-narrative characters or figures without stories have been discussed extensively from the intersection of Japanese studies and media studies. They allude to personal agency, but circulate across texts, worlds, and fictions mutually exclusive to each other, or not sufficiently characterized as narrative at all (Wilde, “Transmedia Character Studies”). In Japanese, the usage of terms such as “pre- or proto-narrative” instead of “extra-narrative” indicates that such a decontextualized figure is thought to be a more fundamental phenomenon than a contextualized one (see Wilde, “Kyara” and “Recontextualizing”). Their “pre-narrative” state is not so much based on a lack of narrative information (which can and must always be supplemented by recipients to varying degrees), but on the (over)abundance of competing and utterly incoherent information. They are recognizable only through recurring iconographies to which certain character dispositions and associations are connected, but their identity is in no way committed to specific diegetic contexts. As such, they can fit into a wide range of contradictory narratives and storyworlds and retain multiple fictional biographies. To put these points another way, since these figures are “pre-narrative,” they are also “pre-authorial intention,” that is, they are raw material that particular artists can shape in the service of multiple and often contradicting narrative intentions. They are especially suited for transmedial circulation and appropriation, as their authorship rests entirely within the participatory communities, within the networks of communication, in which their medial “life of their own,” their continuous recontextualization, occurs and happens. Uncle Sam emerged “right out of the grass roots” (Ketchum, “The Search for Uncle Sam”). While specific artists such as Thomas Nast or James Montgomery Flagg created the most salient pictorial representations, the figure was and is used by thousands of cartoonists around the world. This is what makes it an interesting test case for a practice-based approach to character studies and for a historical perspective on transmediality. The present contribution is primarily built on Alton Ketchum’s comprehensive history of Uncle Sam from 1959 (see also Ketchum, “The Search”), as well as on the works of historian E. McClung Fleming, and on Donald Dewey’s recent monograph *The Art of Ill Will* (2007), re-reading them against current discussions within transmedial character theory. First, I am going to briefly contextualize the figure in relation to other symbols and cyphers for the United States that were commonly used in the seventeenth and eighteenth-century. I will especially focus on the development of a recognizable transmedial iconography in the nineteenth century influenced by a range of fictional as well as non-fictional sources. I will then take a look at the works of Thomas Nast who turned Uncle Sam into a recurring fictional protagonist within his oeuvre before other artists developed their own iterations. I’d like to show how this multiplication of identity can be seen as a catalyst to transform Uncle Sam into a transfictional character typical for the rapidly developing character culture at the end of the nineteenth century, and into an important link between earlier pictorial symbols and later comic book characters/figures such as the Yellow Kid. **A Short Pre-History of Uncle Sam** Uncle Sam was not initially the symbol of the new nation, but only gradually emerged over the first century of its history. By the end of the Civil War, however, he was the pre- eminent symbol of the United States. Here’s the main outline of that pre-his- tory. The first personification of (and symbol for) the “New World” developed in the seventeenth century was Pocahontas, a muscular young Native American woman (Fleming, “The American Image”). Many other symbols came and went in the 18th century, such as Minerva, the goddess of wisdom, adopted from the British Britannia. After the nation had won its independence, the female symbol was more and more referred to as “Columbia,” the personification of the purer and more idealistic aspects of the “American Dream” (Fleming, “From Indian Princess”). Often, these symbols were also fused together: In a French painting from 1786 by Jean Duplessis-Bertaux, for instance, we see a Pocahontas with her established Native American costume and a liberty pole in one hand, towering over the vanquished British Lion, this time completely “whitewashed” as she assumed the iconography of Columbia. The first male figure that had a similar status as a national personification was the protagonist of the eponymous song “Yankee Doodle,” dating back to Andrew Barton’s comic opera The Disappointment (1767). Yankee Doodle was not a pictorial character, however, mostly referred to verbally. He soon developed into “Brother Jonathan,” a stereotypical New England country boy and common man (Morgan 18–21). At first, he was also only used in verbal references and idioms. In articles from the 1770s, “Yankee Doodle” and “Brother Jonathan” were in fact employed interchangeably (Ketchum, Uncle Sam 27–33). A first visual description of Brother Jonathan is given in James K. Paulding’s book The Diverting History of John Bull and Brother Jonathan from 1812 which also featured illustrations (in its 3rd edition from 1827). From then on, Brother Jonathan appeared in broadside cartoons where he came to stand for the “American everyman” (Morgan 63–118). Throughout, however, Brother Jonathan’s appearance was far from uniform and there was no fixed iconography. Most illustrations would thus contain the written mention of his name somewhere. How and when did Uncle Sam take over the mantle of Brother Jonathan? The first written reference in which “Uncle Sam” is used as a synonym for the United States government can be found in spring 1813 in a caption accompanying a caricature of Napoleon on a broadside: “If uncle [sic] Sam needs, I’ll be glad to assist him / For it makes my heart bleed we live at such a distance / If he calls me to Quebec, I’ll lead on the van / And for Johnny Bull we’ll not leave him a man” (qtd. in Ketchum, Uncle Sam 40). From then on, written references to the name multiplied in newspapers and sheets. The origin to the figure would only be revealed 17 years later to a general public when an anonymous “eyewitness” published an article in the New York Gazette on May 12, 1930 in which he linked the name to a Samuel Wilson working as a contractor for the American military in the War of 1812 (Ketchum, Uncle Sam 38–44). Sam Wilson and his brother butchered and packed cattle and produced the salt casks for the troops stationed at the city of Troy in Northern New York. Each of the large casks and packages was marked with the letters “U. S.” Since the acronym for “United States” was not in wide circulation yet, people referred to “Uncle Sam providing for the troops” (Fischer 230). The first unsigned lithograph depicting Uncle Sam is probably from 1832 (“Uncle Sam in Danger”), commenting on Andrew Jackson’s efforts to destroy the Bank of the United States (see figure 1). In the illustration there is a seated Sam, smooth-shaven and young, stout and round-faced, but already covered in an American flag. One cartoon from 1837, Edward Williams Clay’s hand-colored In the 1830s cartoons developed rapidly due to new printing technologies, especially lithography. It made the production and reproduction of pictorial materials much cheaper and easier. Before, cartoons had not reached the public press and were mainly distributed as broadsides for hand-to-hand circulation or posting. Uncle Sam figures circulated prominently in cartoons from 1830–1850. He was not yet cast in a single mold, however, as each artist (probably none of whom had actually met Samuel Wilson) created their own version or used local models for individual appearances. Some dressed him exactly like Brother Jonathan before, as in one sketch by H. Bucholzer from 1844, “Uncle Sam and his Servants” (Ketchum, Uncle Sam 67). There was also the opposite development: Brother Jonathan was often presented with whiskers or stars and stripes on his clothing, the first time in a Punch-cartoon by John Leech from 1856 (73). After the Civil War Brother Jonathan disappeared almost completely in the United States (but not so in Europe), a development Ketchum connects to the new power of the central government that Uncle Sam personifies above all else. The figure gradually assumed the iconography and appearance we know him by today. The influences on this iconography are interesting to trace. The British Punch magazine was probably the first to show Brother Jonathan with a beard, which was quickly adopted elsewhere. Responsible for the new prominence of the beard was most certainly Abraham Lincoln who was also used as a stand-in for the US govern- ment. Lincoln was increasingly presented wearing the stars and stripes transferred to Uncle Sam later (see figure 2). There are even many “hybrid entities” between both. An 1861 cartoon by T. W. Strong, “The Schoolmaster Abroad,” shows a beardless Lincoln in stars and stripes, whereas an unsigned lithograph of the same year (titled “Uncle Sam Protecting his Property against the Encroachments of His Cousin John”) features an Uncle Sam dressed as a Union officer with Lincoln’s face (83). Another sort of real-world inspiration was Dan Rice, one of the first famous American clowns whose appearance likely inspired Thomas Nast (and later James Montgomery Flagg) as he also impersonated Uncle Sam in his shows when the five Ringling Brothers started their circus in 1870. All these sources—some fictional such as Yankee Doodle or Brother Jonathan, some non-fictional like Lincoln or Rice—merged into a transmedial iconography. In 1865 we can find one of the last appearances of a beardless Uncle Sam, strongly reminiscent of the Brother Jonathan he had replaced (figure 3). The bearded image of Lincoln as the champion of the Union had been etched so deeply in Americans’ minds that it was retained in journals such as Harper’s and Leslie’s Weekly, Vanity Fair and Punchinello. From now on, the medial format of the cartoon was part of newspaper culture and the times of autonomous lithographs or broadsides were gone. The decades immediately afterwards are now considered the “Golden Age of American Political Cartoons” (Culbertson 277). Uncle Sam after the Civil War Early newspaper and cartoon culture was the era of Thomas Nast, “America’s foremost pictorial journalist” (Ketchum, *Uncle Sam* 87). His influence on American popular and political culture can hardly be overestimated (see Justice; Halloran; and especially Vinson 29). Nast was famous enough to feature as a character in his drawings himself, and he invented many of the tropes and techniques of modern political cartoons. Importantly, he also experimented with a new form of running gags, “a recurrent theme or personality that serves to knit together a series of cartoons on the same general subject” (Ketchum, Uncle Sam 94). By doing so, his stock of characters turned into recognizable serial figures, and he invented a whole repertoire of recurring protagonists. Many of those were re-used by other artists and became part of the cultural vocabulary, such as the Tweed Ring, the Tammany Tiger, the Rag Baby of Inflation, or the Republican Elephant. Nast finally redefined Uncle Sam by solidifying his character traits and appearances (figure 4). The fame of Uncle Sam as a serial figure could not be overlooked in the 1870s, as many other cartoonists developed their own, personally branded iterations. The Austrian immigrant Joseph Keppler, founder and lead cartoonist of Puck, created a pot-bellied Uncle Sam who looked rather like a German music hall comedian of that era. In contrast, W. A. Rogers developed a serious, no-nonsense iteration. Homer Davenport, the leading cartoonist of the Hearst newspapers during the 1890s, created many serialized strips featuring Uncle Sam that were later re-published in separate collections (Ketchum, Uncle Sam 95–110). Uncle Sam became so prominent in the 1880s that he could increasingly be recognized without his regular clothing and take on different costumes since his facial iconography was salient enough for a general audience to recognize. In a cartoon by Frederic Opper (who would later become the creator of the Happy Hooligan comic strips), we find Sam garbed as a New York policeman (figure 5). As a truly transfictional character, “he” could now sustain various versions of himself with a different age, gender, or social status, as the iconography is not bound to any storyworld or other requirements of semantic consistency (see Ketchum, *Uncle Sam* 133; Palczewski). What does this tell us about our initial questions regarding the affordances and limitations for character traits of such pre-narrative characters? It is certainly possible to apply Jan-Noël Thon’s *network model* of transmedia character instances to Uncle Sam: *Some* iterations of “local work-specific characters” would accordingly coalesce into a “glocal transmedia character” (187–88), such as *all* “Uncle Sams” within the individual cartoons of Thomas Nast. Other iterations, however, can clearly be distinguished from *that* version. Uncle Sam as a “cultural icon” might be better addressed accordingly in terms of a “global transmedia character *network*” (188, emphasis mine). The network model certainly works well for later occurrences of the figure as a character within narrative comic books such as Quality Comics’ (later DC) *National Comics* #1 (1940) for which Will Eisner reimagined Sam as a generic superhero (to be integrated within DC’s complex comic book “multiverse” later), the two-issue Vertigo comic *U. S.—Uncle Sam* (2007) by Steve Darnall and Alex Ross, or the ongoing Image series *Undiscovered Country* (2019–present) by Scott Snyder and Charles Soule. In all these works, a fictional being of the name and iconography is presented as a contextualized diegetic character, distinguished from other “network nodes” through mutually closed textual worlds (*Undiscovered Country* multiplies his identity once again, as there seem to exist many different versions of Sam even within Snyder’s and Soule’s storyworld). The editorial cartoon as a medial format generally follows different logics: Carlos A. Scolari, Paolo Bertetti, and Matthew Freeman have convincingly argued that “older forms of transmedia franchises were constructed on character sharing rather than on the logics of a particular world” (17). As I hope I have indicated, individual cartoons of specific artists, as well as the figures appearing within them, were never bound to the requirements of storyworld consistency. The respective pre-narrative figure could more properly be understood as a kind of *reified* "transmedia character template" consisting only of "physical, mental, and social characteristics [. . .] that any work-specific character sharing the same name may or may not exhibit" (Thon 184, emphasis mine). There are additional symbolic meanings applied to this reified template, but not any "narrative facts" concerned with continuity, existence, or consistency. Like other pictorial symbols (such as flags or logos), pre-narrative figures such as Uncle Sam—more specifically their verbal denominators and/or their iconographies—seem to possess a range of relatively stable, signified symbolic *meanings* (the United States Government, Freedom, Hope—different ones for artists from other countries) *without* any consistent "storyworld entity" through which they are mediated. Due to their anthropomorphic shape and their implied personal agency within represented contexts, however, these pre-narrative figures afford individual expressions within (very local) "storyworld situations" which are far from stable from any picture to the next. To the contrary, pre-narrative figures can be used to generate an infinite number of pictorial expressions. This perspective is not even limited to the analysis of texts (including cartoons and other pictorial artifacts). It also entails performances and practices. Just like Brother Jonathan before him, Uncle Sam, too, could be found on the stage (Morgan 37–62). By the 1890s he was impersonated at festivals, parades, and fairs, and he was long a standard fixture of the circus. A few years later he even made an appearance in George M. Cohan’s Broadway musical show “Little Johnny Jones” (1903, adapted to film as *Yankee Doodle Dandy* in 1942). Uncle Sam has thus become a transmedial nodal point of practices and performances, connecting the works of countless authors and artists, amateurs, and professionals alike, without any story, storyworld, or author (collective) to “fixate” or guarantee his identity. Not even is any clear-cut distinction to the earlier Brother Jonathan possible, and neither to Yankee Doodle preceding both. As scholars such as Roger Sabin (2009) or Christina Meyer (2019) have pointed out, 19th century characters/figures like Ally Sloper or the Yellow Kid were intentionally designed to transcend their origins in print to become cultural resources for the general public in a variety of media. In media historical terms, political cartoons that did not merely comment upon existing public persons but instead developed their own inventory of symbolic, pre-narrative figures can then be seen as an important link between earlier, more “static” pictorial personifications of—and symbols for—countries and ideas on the one hand and the emergence of serial characters within comic books and other narrative media on the other. **Acknowledgments** This research was first presented on the International Symposium of British and American Studies “Nineteenth-Century Transmedia Practices” at the University of Vienna, January 30–February 2, 2020. I am grateful to the organizers Christina Meyer and Monika Pietrzak-Franger for many valuable observation and suggestions. Works Cited The Politics of Pre-Narrative Seriality Shane Denson LOOKING AT THE EMERGENCE AND TRANSFORMATION of Uncle Sam in political cartoons of the nineteenth century, Lukas R. A. Wilde argues that the figure serves as a historical and/or conceptual link between more or less static allegorizations or stock characters and the more fully fleshed out characters of today’s transmedia storyworlds. Existing in this in-between space and subject to constant repetition and variation without respect for the integrity or coherence of diegetic boundaries, Uncle Sam is close in spirit to the “serial figures” that Ruth Mayer and I have theorized from a media-theoretical perspective (“Grenzgänger”; “Border Crossings”). Figures like Dracula, Tarzan, and Frankenstein’s monster also serve as historical links or nodes, connecting a variety of media and thus historicizing transformations of the larger media ecologies in which they participate (see Denson; Denson and Mayer, “Bildstörung,” “Spectral Seriality”; Mayer). Shifts in literary culture as occasioned by the rise of the steam press, the proliferation of film and comics in the late nineteenth century, the cinema’s transition to sound and the addition of color, the rise of radio and television, and the advent of the digital—all of these changes are tracked, serially and self-reflexively, by figures that exceed their instantiation in any one particular medium and thus serve as indices of the material-technological infrastructures of social-discursive communication and interrelation. A similar argument could surely be constructed around Uncle Sam’s various appearances in newspaper comics, animated cartoons, cinematic and televisual representations, and so on, but since we are dealing with shifting personifications of a real-world nation state rather than various retellings of a fictional story, the stakes of the figure’s seriality are even more clearly political, as it mediates domestic and international perceptions of a country’s military, trade, and diplomatic powers. Moreover, Wilde’s quasi-narratological framing of the figure as a “pre-narrative character” shifts attention from serial figures’ engagements with technological substrates to the serial conditions of discursive identification and difference, participatory sociality, and politics. These differences of emphasis or of focus should not, however, be taken as signs of substantive disagreement or incompatibility. Rather, the two approaches are, I believe, complementary, and when placed in conversation they may together illuminate the interplay between medial substrates and sociopolitical formations. In order to further this dialogue, I would like to take up Wilde’s concept of the “pre-narrative character” and to subject it to a kind of conceptual figure/ground reversal: whereas Wilde asks about the pre-narrativity of a particular type of character, I would like to ask, conversely, “What is the character of pre-narrativity itself?” Accordingly, I aim to shift our focus from the “character,” as the locus of fictional biography or subjectivity, to a characteristic (or set of characteristics) pertaining to a pre-narrative level of mediation. Is the pre-narrative character, in its proximity to the serial figure, itself a figuration of the pre-narrative or even pre-discursive aspects of media and the role they play in the serialized articulation of political agency? Wilde points to the primacy accorded in the Japanese context to “pre- or proto-narrative” agency, such that “a decontextualized figure is thought to be a more fundamental phenomenon than a contextualized one.” Wilde implies that this marks a significant difference both from the conventional privileging of coherently narrativized (or psychologized) characters, as well as from an “extra-narrative” focus that identifies such characters’ intertextual or self-reflexive excess. Whereas the latter marks a surplus in addition to the fictional subject’s diegetic biography and agency (the primacy of which is therefore presupposed and left intact), the “pre- or proto-narrative” subtends such agency as its precondition. It is an indeterminate or subtractive force, a set of relations out of which more determinate subjectivities and object-worlds may emerge. Though Wilde is concerned with the construction and circulation of fictional characters, his assertion of pre-subjective conditions of possibility suggests interesting parallels with the phenomenology of human agency that might hold the key to the political efficacy of serial mediation more generally. Indeed, seriality has been theorized as vacillating between sequential production/reception practices (such as characterize serialized novels or television series) and the social formations that emerge around various media and material infrastructures (Benedict Anderson’s “imagined communities” organized around newspapers, novels, and the census [see Anderson], or Jean-Paul Sartre’s theorization of the seriality as a loose, anonymous collective that gathers randomly at a city bus stop or that is “alone together” in its shared reception of a radio broadcast [see Sartre]). The primacy of the pre-narrative, for Wilde, mirrors the primacy that Sartre accords to the social seriality over the more organized (or, as Wilde puts it, “contextualized”) agency of the group-in-formation. Whereas the group is defined by shared goals and objectives that condition its members’ subjective and collective perceptions and actions, the seriality is constituted passively in relation to commodities, media, and built structures—what Sartre calls the “practico-inert” in light of the way that “worked matter” transmits the praxis of past living labor into the present, exerting an inertial force that shapes or sets the parameters for agency. In life as in media, we are dealing here with a pre-narrative or pre-personal ground for subjective and collective agency, which serialized media simultaneously figure (in the guise of the pre-narrative character) and of which they are a material part. Clearly, the “life” of a pre-narrative character/serial figure is not the same as the life of a real human subject, but its diffuse agency, which for Wilde “is not so much based on a lack of narrative information [. . .] but on the (over)abundance of competing and utterly incoherent information,” is a part of this practico-inert reality that forms the common, shared substrate of collective human existence. It is a pre-condition of political agency itself, not merely as an ideological reflection but as a self-reflexive component of the pre-narratively serialized materiality against which more determinate social formations may emerge. Wilde writes that pre-narrative characters “are especially suited for transmedial circulation and appropriation, as their authorship rests entirely within the participatory communities, within the networks of communication, in which their medial ‘life of their own,’ their continuous recontextualization, occurs and happens.” Importantly, their political agency resides within “the networks of communication” rather than determinate communications themselves; they phatically probe the channels within which “participatory communities” may discover or affirm themselves, but which they do not pre-exist. Such figures are therefore serial in both of the senses referenced above: on the one hand, their existence depends upon sequences of repetition and variation, while on the other hand such sequences provide the substance of a serial (social) formation in Sartre’s sense—the glue that binds communities in their basic, mostly anonymous relations, but that serves also as the pre-narrative condition of possibility for the formation of more robust political ties. Works Cited Material Practices and Semiotic Objects: A Response to Shane Denson Lukas R. A. Wilde THE THOUGHTS AND OBSERVATIONS addressed in Shane Denson’s “The Politics of Pre-Narrative Seriality” bring together and open up various lines of reflection not taken up in my article on Uncle Sam. I see my proposed notion of “pre- or proto-narrative figures” indeed complementary to Denson’s and Mayer’s groundbreaking concept of “serial figures” to which many of my ideas are owed. As Denson remarks aptly, my approach could be characterized as broadly narratological, at least insofar as I highlight the limits of comprehending an anthropomorphic being as belonging to a (specific) course of events situated within a (specific) possible world. The concept of the serial figure allows that as well, although with one difference that I find illuminating: distinguished from actual “series characters” (which are unequivocally constrained to “the more or less closed fictional universe of a serially-ongoing narrative” [Denson and Mayer 67]), the serial figure is conceptualized as either too contradictory (exhibiting a “palimpsest-like biography” and “branching genealogies” [68]) or as too “flat and unchanging” (67) to afford any linear progression (or, possibly, as both). For the former (contradictory versions), a number of conceptual lenses have been proposed by various authors (see Wilde, “Kyara”) to capture the fact that under certain historical, medial, and generic conditions, distinctions are continuously drawn in terms of continuity and canonicity (and often negotiated and contested)—which consequently do amount to different characters by the same name, or as a network of character versions in Thon’s model. What makes the concept of the “serial figure” more original, in my view, is the fact that it can also be applied to entirely “flat and unchanging” cases where continuity or canonicity—one of the backbones of the network-model—are never strong expectations to begin with. Serial figures in that specific sense are then close to what Thon addresses as the “transmedia character template” of prototypical properties shared by many or most nodes within the network. That not many alternative descriptions are available in “Western” literature (in clear contrast to Japanese investigations) seems mainly owed to the fact that characters are usually talked about by literary, film, or theater scholars—interested in narrative media, once again. Denson and Mayer, however, approach their subjects from the perspective of material and social practices, a seriality not merely (or not even primarily) in terms of represented content, but especially related to materiality, sociality, economy, politics, or identity formation. I would agree that the most pressing lines of inquiry into characters and figures should concern “the substance of a serial (social) formation [. . .]—the glue that binds communities in their basic, mostly anonymous relations” beyond or prior to any intersubjective construction of stories or storyworlds. I would like to emphasize, however, that the social formation of collective subjectivity has a semiotic side as well, especially where it is focused on characters or figures appearing in heterogeneous material contexts that have otherwise not much in common to each other (such as Hello Kitty products). As a dynamic semiotic object (in the sense of Peirce, see Wilde, “Kyara”) “they” can only be experienced as social resistance to, agreement with, or a playful (re)appropriation of existing characters/figures in different settings, worlds, ages, genders, or ethnicities—not only when canonicity and continuity is managed and/or contested (often against the authority of actual intellectual property rights holders) but especially when such matters are irrelevant to begin with. Pre-narrative figures such as Uncle Sam—in their striking difference not only to actual persons as well as to coherent “series characters,” but also to networks of strongly differentiated character-versions—might thus, for better or worse, facilitate especially “durable” imagined communities.
Abstract This document specifies how to use the Session Initiation Protocol (SIP) to establish a Secure Real-time Transport Protocol (SRTP) security context using the Datagram Transport Layer Security (DTLS) protocol. It describes a mechanism of transporting a fingerprint attribute in the Session Description Protocol (SDP) that identifies the key that will be presented during the DTLS handshake. The key exchange travels along the media path as opposed to the signaling path. The SIP Identity mechanism can be used to protect the integrity of the fingerprint attribute from modification by intermediate proxies. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc5763. 7. Example Message Flow ............................................4 7.1. Basic Message Flow with Early Media and SIP Identity ...4 7.2. Basic Message Flow with Connected Identity (RFC 4916) ...9 7.3. Basic Message Flow with STUN Check for NAT Case .......23 8. Security Considerations ........................................25 8.1. Responder Identity .......................................25 8.2. SIPS ....................................................26 8.3. S/MIME ..................................................26 8.4. Continuity of Authentication .............................26 8.5. Short Authentication String ..............................27 8.6. Limits of Identity Assertions ............................27 8.7. Third-Party Certificates .................................29 8.8. Perfect Forward Secrecy ................................29 9. Acknowledgments ................................................29 10. References ....................................................30 10.1. Normative References ..................................30 10.2. Informative References ................................31 Appendix A. Requirements Analysis ................................33 A.1. Forking and Retargeting (R-FORK-RETARGET, R-BEST-SECURE, R-DISTINCT) .........33 A.2. Distinct Cryptographic Contexts (R-DISTINCT) ..........33 A.3. Reusage of a Security Context (R-REUSE) .................33 A.4. Clipping (R-AVOID-CLIPPING) ............................33 A.5. Passive Attacks on the Media Path (R-PASS-MEDIA) .......33 A.6. Passive Attacks on the Signaling Path (R-PASS-SIG) .......34 A.7. (R-SIG-MEDIA, R-ACT-ACT) .............................34 A.8. Binding to Identifiers (R-ID-BINDING) ...................34 A.9. Perfect Forward Secrecy (R-PFS) ........................34 A.10. Algorithm Negotiation (R-COMPUTE) ......................35 A.11. RTP Validity Check (R-RTP-VALID) .......................35 A.12. Third-Party Certificates (R-CERTS, R-EXISTING) .........35 A.13. FIPS 140-2 (R-FIPS) ..................................35 A.14. Linkage between Keying Exchange and SIP Signaling (R-ASSOC) .....................35 A.15. Denial-of-Service Vulnerability (R-DOS) .................35 A.16. Crypto-Agility (R-AGILITY) ............................35 A.17. Downgrading Protection (R-DOWNGRADE) ..................36 A.18. Media Security Negotiation (R-NEGOTIATE) ............36 A.19. Signaling Protocol Independence (R-OTHER-SIGNALING) ......36 A.20. Media Recording (R-RECORDING) .........................36 A.21. Interworking with Intermediaries (R-TRANSCODER) ........36 A.22. PSTN Gateway Termination (R-PSTN) .....................36 A.23. R-ALLOW-RTP ..........................................36 A.24. R-HERFP ..............................................37 1. Introduction The Session Initiation Protocol (SIP) [RFC3261] and the Session Description Protocol (SDP) [RFC4566] are used to set up multimedia sessions or calls. SDP is also used to set up TCP [RFC4145] and additionally TCP/TLS connections for usage with media sessions [RFC4572]. The Real-time Transport Protocol (RTP) [RFC3550] is used to transmit real-time media on top of UDP and TCP [RFC4571]. Datagram TLS [RFC4347] was introduced to allow TLS functionality to be applied to datagram transport protocols, such as UDP and DCCP. This document provides guidelines on how to establish SRTP [RFC3711] security over UDP using an extension to DTLS (see [RFC5764]). The goal of this work is to provide a key negotiation technique that allows encrypted communication between devices with no prior relationships. It also does not require the devices to trust every call signaling element that was involved in routing or session setup. This approach does not require any extra effort by end users and does not require deployment of certificates that are signed by a well-known certificate authority to all devices. The media is transported over a mutually authenticated DTLS session where both sides have certificates. It is very important to note that certificates are being used purely as a carrier for the public keys of the peers. This is required because DTLS does not have a mode for carrying bare keys, but it is purely an issue of formatting. The certificates can be self-signed and completely self-generated. All major TLS stacks have the capability to generate such certificates on demand. However, third-party certificates MAY also be used if the peers have them (thus reducing the need to trust intermediaries). The certificate fingerprints are sent in SDP over SIP as part of the offer/answer exchange. The fingerprint mechanism allows one side of the connection to verify that the certificate presented in the DTLS handshake matches the certificate used by the party in the signaling. However, this requires some form of integrity protection on the signaling. S/MIME signatures, as described in RFC 3261, or SIP Identity, as described in [RFC4474], provide the highest level of security because they are not susceptible to modification by malicious intermediaries. However, even hop-by-hop security, such as provided by SIPS, offers some protection against modification by attackers who are not in control of on-path signaling elements. Because DTLS-SRTP only requires message integrity and not confidentiality for the signaling, the number of elements that must have credentials and be trusted is significantly reduced. In particular, if RFC 4474 is used, only the Authentication Service need have a certificate and be trusted. Intermediate elements cannot undetectably modify the message and therefore cannot mount a man-in-the-middle (MITM) attack. By comparison, because SDESCRIPTIONS [RFC4568] requires confidentiality for the signaling, all intermediate elements must be trusted. This approach differs from previous attempts to secure media traffic where the authentication and key exchange protocol (e.g., Multimedia Internet KEYing (MIKEY) [RFC3830]) is piggybacked in the signaling message exchange. With DTLS-SRTP, establishing the protection of the media traffic between the endpoints is done by the media endpoints with only a cryptographic binding of the media keying to the SIP/SDP communication. It allows RTP and SIP to be used in the usual manner when there is no encrypted media. In SIP, typically the caller sends an offer and the callee may subsequently send one-way media back to the caller before a SIP answer is received by the caller. The approach in this specification, where the media key negotiation is decoupled from the SIP signaling, allows the early media to be set up before the SIP answer is received while preserving the important security property of allowing the media sender to choose some of the keying material for the media. This also allows the media sessions to be changed, rekeyed, and otherwise modified after the initial SIP signaling without any additional SIP signaling. Design decisions that influence the applicability of this specification are discussed in Section 3. 2. Overview Endpoints wishing to set up an RTP media session do so by exchanging offers and answers in SDP messages over SIP. In a typical use case, two endpoints would negotiate to transmit audio data over RTP using the UDP protocol. Figure 1 shows a typical message exchange in the SIP trapezoid. Consider Alice wanting to set up an encrypted audio session with Bob. Both Bob and Alice could use public-key-based authentication in order to establish a confidentiality protected channel using DTLS. Since providing mutual authentication between two arbitrary endpoints on the Internet using public-key-based cryptography tends to be problematic, we consider more deployment-friendly alternatives. This document uses one approach and several others are discussed in Section 8. Alice sends an SDP offer to Bob over SIP. If Alice uses only self-signed certificates for the communication with Bob, a fingerprint is included in the SDP offer/answer exchange. This fingerprint binds the DTLS key exchange in the media plane to the signaling plane. The fingerprint alone protects against active attacks on the media but not active attacks on the signaling. In order to prevent active attacks on the signaling, "Enhancements for Authenticated Identity Management in the Session Initiation Protocol (SIP)" [RFC4474] may be used. When Bob receives the offer, the peers establish some number of DTLS connections (depending on the number of media sessions) with mutual DTLS authentication (i.e., both sides provide certificates). At this point, Bob can verify that Alice’s credentials offered in TLS match the fingerprint in the SDP offer, and Bob can begin sending media to Alice. Once Bob accepts Alice’s offer and sends an SDP answer to Alice, Alice can begin sending confidential media to Bob over the appropriate streams. Alice and Bob will verify that the fingerprints from the certificates received over the DTLS handshakes match with the fingerprints received in the SDP of the SIP signaling. This provides the security property that Alice knows that the media traffic is going to Bob and vice versa without necessarily requiring global Public Key Infrastructure (PKI) certificates for Alice and Bob. (See Section 8 for detailed security analysis.) 3. Motivation Although there is already prior work in this area (e.g., Security Descriptions for SDP [RFC4568], Key Management Extensions [RFC4567] combined with MIKEY [RFC3830] for authentication and key exchange), this specification is motivated as follows: - TLS will be used to offer security for connection-oriented media. The design of TLS is well-known and implementations are widely available. - This approach deals with forking and early media without requiring support for Provisional Response ACKnowledgement (PRACK) [RFC3262] while preserving the important security property of allowing the offerer to choose keying material for encrypting the media. - The establishment of security protection for the media path is also provided along the media path and not over the signaling path. In many deployment scenarios, the signaling and media traffic travel along a different path through the network. - When RFC 4474 is used, this solution works even when the SIP proxies downstream of the authentication service are not trusted. There is no need to reveal keys in the SIP signaling or in the SDP message exchange, as is done in SDESCRIPTIONS [RFC4568]. Retargeting of a dialog-forming request (changing the value of the Request-URI), the User Agent (UA) that receives it (the User Agent Server, UAS) can have a different identity from that in the To header field. When RFC 4916 is used, then it is possible to supply its identity to the peer UA by means of a request in the reverse direction, and for that identity to be signed by an Authentication Service. - In this method, synchronization source (SSRC) collisions do not result in any extra SIP signaling. 4. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. DTLS/TLS uses the term "session" to refer to a long-lived set of keying material that spans associations. In this document, consistent with SIP/SDP usage, we use it to refer to a multimedia session and use the term "TLS session" to refer to the TLS construct. We use the term "association" to refer to a particular DTLS cipher suite and keying material set that is associated with a single host/port quartet. The same DTLS/TLS session can be used to establish the keying material for multiple associations. For consistency with other SIP/SDP usage, we use the term "connection" when what’s being referred to is a multimedia stream that is not specifically DTLS/TLS. In this document, the term "Mutual DTLS" indicates that both the DTLS client and server present certificates even if one or both certificates are self-signed. 5. Establishing a Secure Channel The two endpoints in the exchange present their identities as part of the DTLS handshake procedure using certificates. This document uses certificates in the same style as described in "Connection-Oriented Media Transport over the Transport Layer Security (TLS) Protocol in the Session Description Protocol (SDP)" [RFC4572]. If self-signed certificates are used, the content of the subjectAltName attribute inside the certificate MAY use the uniform resource identifier (URI) of the user. This is useful for debugging purposes only and is not required to bind the certificate to one of the communication endpoints. The integrity of the certificate is ensured through the fingerprint attribute in the SDP. The subjectAltName is not an important component of the certificate verification. The generation of public/private key pairs is relatively expensive. Endpoints are not required to generate certificates for each session. The offer/answer model, defined in [RFC3264], is used by protocols like the Session Initiation Protocol (SIP) [RFC3261] to set up multimedia sessions. In addition to the usual contents of an SDP When an endpoint wishes to set up a secure media session with another endpoint, it sends an offer in a SIP message to the other endpoint. This offer includes, as part of the SDP payload, the fingerprint of the certificate that the endpoint wants to use. The endpoint SHOULD send the SIP message containing the offer to the offerer’s SIP proxy over an integrity protected channel. The proxy SHOULD add an Identity header field according to the procedures outlined in [RFC4474]. The SIP message containing the offer SHOULD be sent to the offerer’s SIP proxy over an integrity protected channel. When the far endpoint receives the SIP message, it can verify the identity of the sender using the Identity header field. Since the Identity header field is a digital signature across several SIP header fields, in addition to the body of the SIP message, the receiver can also be certain that the message has not been tampered with after the digital signature was applied and added to the SIP message. The far endpoint (answerer) may now establish a DTLS association with the offerer. Alternately, it can indicate in its answer that the offerer is to initiate the TLS association. In either case, mutual DTLS certificate-based authentication will be used. After completing the DTLS handshake, information about the authenticated identities, including the certificates, are made available to the endpoint application. The answerer is then able to verify that the offerer’s certificate used for authentication in the DTLS handshake can be associated to the certificate fingerprint contained in the offer in the SDP. At this point, the answerer may indicate to the end user that the media is secured. The offerer may only tentatively accept the answerer’s certificate since it may not yet have the answerer’s certificate fingerprint. When the answerer accepts the offer, it provides an answer back to the offerer containing the answerer’s certificate fingerprint. At this point, the offerer can accept or reject the peer’s certificate and the offerer can indicate to the end user that the media is secured. Note that the entire authentication and key exchange for securing the media traffic is handled in the media path through DTLS. The signaling path is only used to verify the peers’ certificate fingerprints. The offer and answer MUST conform to the following requirements. - The endpoint MUST use the setup attribute defined in [RFC4145]. The endpoint that is the offerer MUST use the setup attribute value of setup:actpass and be prepared to receive a client_hello before it receives the answer. The answerer MUST use either a setup attribute value of setup:active or setup:passive. Note that if the answerer uses setup:passive, then the DTLS handshake will not begin until the answerer is received, which adds additional latency. setup:active allows the answer and the DTLS handshake to occur in parallel. Thus, setup:active is RECOMMENDED. Whichever party is active MUST initiate a DTLS handshake by sending a ClientHello over each flow (host/port quartet). - The endpoint MUST NOT use the connection attribute defined in [RFC4145]. - The endpoint MUST use the certificate fingerprint attribute as specified in [RFC4572]. - The certificate presented during the DTLS handshake MUST match the fingerprint exchanged via the signaling path in the SDP. The security properties of this mechanism are described in Section 8. - If the fingerprint does not match the hashed certificate, then the endpoint MUST tear down the media session immediately. Note that it is permissible to wait until the other side’s fingerprint has been received before establishing the connection; however, this may have undesirable latency effects. 6. Miscellaneous Considerations 6.1. Anonymous Calls The use of DTLS-SRTP does not provide anonymous calling; however, it also does not prevent it. However, if care is not taken when anonymous calling features, such as those described in [RFC3325] or [RFC5767] are used, DTLS-SRTP may allow deanonymizing an otherwise anonymous call. When anonymous calls are being made, the following procedures SHOULD be used to prevent deanonymization. When making anonymous calls, a new self-signed certificate SHOULD be used for each call so that the calls cannot be correlated as to being from the same caller. In situations where some degree of correlation is acceptable, the same certificate SHOULD be used for a number of calls in order to enable continuity of authentication; see Section 8.4. Additionally, note that in networks that deploy [RFC3325], RFC 3325 requires that the Privacy header field value defined in [RFC3323] needs to be set to ‘id’. This is used in conjunction with the SIP identity mechanism to ensure that the identity of the user is not asserted when enabling anonymous calls. Furthermore, the content of the subjectAltName attribute inside the certificate MUST NOT contain information that either allows correlation or identification of the user that wishes to place an anonymous call. Note that following this recommendation is not sufficient to provide anonymization. 6.2. Early Media If an offer is received by an endpoint that wishes to provide early media, it MUST take the setup:active role and can immediately establish a DTLS association with the other endpoint and begin sending media. The setup:passive endpoint may not yet have validated the fingerprint of the active endpoint’s certificate. The security aspects of media handling in this situation are discussed in Section 8. 6.3. Forking In SIP, it is possible for a request to fork to multiple endpoints. Each forked request can result in a different answer. Assuming that the requester provided an offer, each of the answerers will provide a unique answer. Each answerer will form a DTLS association with the offerer. The offerer can then securely correlate the SDP answer received in the SIP message by comparing the fingerprint in the answer to the hashed certificate for each DTLS association. 6.4. Delayed Offer Calls An endpoint may send a SIP INVITE request with no offer in it. When this occurs, the receiver(s) of the INVITE will provide the offer in the response and the originator will provide the answer in the subsequent ACK request or in the PRACK request [RFC3262], if both endpoints support reliable provisional responses. In any event, the active endpoint still establishes the DTLS association with the passive endpoint as negotiated in the offer/answer exchange. 6.5. Multiple Associations When there are multiple flows (e.g., multiple media streams, non-multiplexed RTP and RTCP, etc.) the active side MAY perform the DTLS handshakes in any order. Appendix B of [RFC5764] provides some guidance on the performance of parallel DTLS handshakes. Note that if the answerer ends up being active, it may only initiate handshakes on some subset of the potential streams (e.g., if audio and video are offered but it only wishes to do audio). If the offerer ends up being active, the complete answer will be received before the offerer begins initiating handshakes. 6.6. Session Modification Once an answer is provided to the offerer, either endpoint MAY request a session modification that MAY include an updated offer. This session modification can be carried in either an INVITE or UPDATE request. The peers can reuse the existing associations if they are compatible (i.e., they have the same key fingerprints and transport parameters), or establish a new one following the same rules are for initial exchanges, tearing down the existing association as soon as the offer/answer exchange is completed. Note that if the active/passive status of the endpoints changes, a new connection MUST be established. 6.7. Middlebox Interaction There are a number of potentially bad interactions between DTLS-SRTP and middleboxes, as documented in [MMUSIC-MEDIA], which also provides recommendations for avoiding such problems. 6.7.1. ICE Interaction Interactive Connectivity Establishment (ICE), as specified in [RFC5245], provides a methodology of allowing participants in multimedia sessions to verify mutual connectivity. When ICE is being used, the ICE connectivity checks are performed before the DTLS handshake begins. Note that if aggressive nomination mode is used, multiple candidate pairs may be marked valid before ICE finally converges on a single candidate pair. Implementations MUST treat all ICE candidate pairs associated with a single component as part of the same DTLS association. Thus, there will be only one DTLS handshake even if there are multiple valid candidate pairs. Note that this may mean adjusting the endpoint IP addresses if the selected candidate pair shifts, just as if the DTLS packets were an ordinary media stream. Note that Simple Traversal of the UDP Protocol through NAT (STUN) packets are sent directly over UDP, not over DTLS. [RFC5764] describes how to demultiplex STUN packets from DTLS packets and SRTP packets. 6.7.2. Latching Control without ICE If ICE is not being used, then there is potential for a bad interaction with Session Border Controllers (SBCs) via "latching", as described in [MMUSIC-MEDIA]. In order to avoid this issue, if ICE is not being used and the DTLS handshake has not completed upon receiving the other side’s SDP, then the passive side MUST do a single unauthenticated STUN [RFC5389] connectivity check in order to open up the appropriate pinhole. All implementations MUST be prepared to answer this request during the handshake period even if they do not otherwise do ICE. However, the active side MUST proceed with the DTLS handshake as appropriate even if no such STUN check is received and the passive MUST NOT wait for a STUN answer before sending its ServerHello. 6.8. Rekeying As with TLS, DTLS endpoints can rekey at any time by redoing the DTLS handshake. While the rekey is under way, the endpoints continue to use the previously established keying material for usage with DTLS. Once the new session keys are established, the session can switch to using these and abandon the old keys. This ensures that latency is not introduced during the rekeying process. Further considerations regarding rekeying in case the SRTP security context is established with DTLS can be found in Section 3.7 of [RFC5764]. 6.9. Conference Servers and Shared Encryptions Contexts It has been proposed that conference servers might use the same encryption context for all of the participants in a conference. The advantage of this approach is that the conference server only needs to encrypt the output for all speakers instead of once per participant. This shared encryption context approach is not possible under this specification because each DTLS handshake establishes fresh keys that are not completely under the control of either side. However, it is argued that the effort to encrypt each RTP packet is small compared to the other tasks performed by the conference server such as the codec processing. Future extensions, such as [SRTP-EKT] or [KEY-TRANSPORT], could be used to provide this functionality in concert with the mechanisms described in this specification. 6.10. Media over SRTP Because DTLS’s data transfer protocol is generic, it is less highly optimized for use with RTP than is SRTP [RFC3711], which has been specifically tuned for that purpose. DTLS-SRTP [RFC5764] has been defined to provide for the negotiation of SRTP transport using a DTLS connection, thus allowing the performance benefits of SRTP with the easy key management of DTLS. The ability to reuse existing SRTP software and hardware implementations may in some environments provide another important motivation for using DTLS-SRTP instead of RTP over DTLS. Implementations of this specification MUST support DTLS-SRTP [RFC5764]. 6.11. Best Effort Encryption [RFC5479] describes a requirement for best-effort encryption where SRTP is used and where both endpoints support it and key negotiation succeeds, otherwise RTP is used. [MMUSIC-SDP] describes a mechanism that can signal both RTP and SRTP as an alternative. This allows an offerer to express a preference for SRTP, but RTP is the default and will be understood by endpoints that do not understand SRTP or this key exchange mechanism. Implementations of this document MUST support [MMUSIC-SDP]. 7. Example Message Flow Prior to establishing the session, both Alice and Bob generate self-signed certificates that are used for a single session or, more likely, reused for multiple sessions. In this example, Alice calls Bob. In this example, we assume that Alice and Bob share the same proxy. 7.1. Basic Message Flow with Early Media and SIP Identity This example shows the SIP message flows where Alice acts as the passive endpoint and Bob acts as the active endpoint; meaning that as soon as Bob receives the INVITE from Alice, with DTLS specified in the "m=" line of the offer, Bob will begin to negotiate a DTLS association with Alice for both RTP and RTCP streams. Early media (RTP and RTCP) starts to flow from Bob to Alice as soon as Bob sends the DTLS finished message to Alice. Bi-directional media (RTP and RTCP) can flow after Alice receives the SIP 200 response and once Alice has sent the DTLS finished message. The SIP signaling from Alice to her proxy is transported over TLS to ensure an integrity protected channel between Alice and her identity service. Transport between proxies should also be protected somehow, especially if SIP Identity is not in use. Alice Proxies Bob (1) INVITE | | ----------------|------------------| (2) INVITE | | ----------------|------------------| (3) hello | | (4) hello | | ----------------|------------------| (5) finished | | (6) media | | (7) finished | | ----------------|------------------| (8) 200 OK | | (9) 200 OK | | ----------------|------------------| (10) media | | (11) ACK | | ----------------|------------------| Message (1): INVITE Alice -> Proxy This shows the initial INVITE from Alice to Bob carried over the TLS transport protocol to ensure an integrity protected channel between Alice and her proxy that acts as Alice’s identity service. Alice has requested to be either the active or passive endpoint by specifying a=setup:actpass in the SDP. Bob chooses to act as the DTLS client and will initiate the session. Also note that there is a fingerprint attribute in the SDP. This is computed from Alice’s self-signed certificate. This offer includes a default "m=" line offering RTP in case the answerer does not support SRTP. However, the potential configuration utilizing a transport of SRTP is preferred. See [MMUSIC-SDP] for more details on the details of SDP capability negotiation. INVITE sip:bob@example.com SIP/2.0 To: <sip:bob@example.com> From: "Alice"<sip:alice@example.com>;tag=843c7b0b Via: SIP/2.0/TLS ua1.example.com;branch=z9hG4bK-0e53sadfkasldkfq Contact: <sip:alice@ua1.example.com> Call-ID: 6076913b1c39c212@REVMTEpG CSeq: 1 INVITE Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE Max-Forwards: 70 Content-Type: application/sdp Content-Length: xxxx Supported: from-change v=0 o=- 1181923068 1181923196 IN IP4 ua1.example.com s=example1 c=IN IP4 ua1.example.com a=setup:actpass t=0 0 m=audio 6056 RTP/AVP 0 a=sendrecv a=tcap:1 UDP/TLS/RTP/SAVP RTP/AVP a=pcfg:1 t=1 Message (2): INVITE Proxy -> Bob This shows the INVITE being relayed to Bob from Alice (and Bob’s) proxy. Note that Alice’s proxy has inserted an Identity and Identity-Info header. This example only shows one element for both proxies for the purposes of simplification. Bob verifies the identity provided with the INVITE. INVITE sip:bob@ua2.example.com SIP/2.0 To: <sip:bob@example.com> From: "Alice"<sip:alice@example.com>;tag=843c7b0b Via: SIP/2.0/TLS proxy.example.com;branch=z9hG4bK-0e53sadfasdk Via: SIP/2.0/TLS ua1.example.com;branch=z9hG4bK-0e53sadfasdkfj Record-Route: <sip:proxy.example.com;lr> Contact: <sip:alice@ua1.example.com> Call-ID: 6076913b1c39c212@REVMTEpG CSeq: 1 INVITE Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE Max-Forwards: 69 Identity: CyI4+nAkHrH3ntmaxgr01TMxTmtjP7MASwliNRdupRI1vpkXRvZXXlja9k 3W+v1PDsy32MagZi0M5WfEkXXbgTnPYW0jIoK8HMyY1VT7egt0kk4XrKFC HYWGCl0nB2sNsP9CG4hq+YJZTMaSROonMUBhikVIjnQ8ykeD6UXNOyfI= Identity-Info: https://example.com/cert Content-Type: application/sdp Content-Length: xxxx Supported: from-change v=0 o=- 1181923068 1181923196 IN IP4 ua1.example.com s=example1 c=IN IP4 ua1.example.com a=setup:actpass t=0 0 m=audio 6056 RTP/AVP 0 a=sendrecv a=tcap:1 UDP/TLS/RTP/SAVP RTP/AVP a=pcfg:1 t=1 Message (3): ClientHello Bob -> Alice Assuming that Alice’s identity is valid, Line 3 shows Bob sending a DTLS ClientHello(s) directly to Alice. In this case, two DTLS ClientHello messages would be sent to Alice: one to ua1.example.com:6056 for RTP and another to port 6057 for RTCP, but only one arrow is drawn for compactness of the figure. Message (4): ServerHello+Certificate Alice -> Bob Alice sends back a ServerHello, Certificate, and ServerHelloDone for both RTP and RTCP associations. Note that the same certificate is used for both the RTP and RTCP associations. If RTP/RTCP multiplexing [RFC5761] were being used only a single association would be required. Message (5): Certificate Bob -> Alice Bob sends a Certificate, ClientKeyExchange, CertificateVerify, change_cipher_spec, and Finished for both RTP and RTCP associations. Again note that Bob uses the same server certificate for both associations. Message (6): Early Media Bob -> Alice At this point, Bob can begin sending early media (RTP and RTCP) to Alice. Note that Alice can’t yet trust the media since the fingerprint has not yet been received. This lack of trusted, secure media is indicated to Alice via the UA user interface. Message (7): Finished Alice -> Bob After Message 7 is received by Bob, Alice sends change_cipher_spec and Finished. Message (8): 200 OK Bob -> Alice When Bob answers the call, Bob sends a 200 OK SIP message that contains the fingerprint for Bob’s certificate. Bob signals the actual transport protocol configuration of SRTP over DTLS in the acfg parameter. SIP/2.0 200 OK To: <sip:bob@example.com>;tag=641891392105372816 From: "Alice" <sip:alice@example.com>;tag=843c7b0b Via: SIP/2.0/TLS proxy.example.com:5061;branch=z9hG4bK-0e53sadfkasldk Via: SIP/2.0/TLS ua1.example.com;branch=z9hG4bK-0e53sadfkasldkfj Record-Route: <sip:proxy.example.com;lr> Call-ID: 6076913b1c39c212@REVMTEpG CSeq: 1 INVITE Contact: <sip:bob@ua2.example.com> Content-Type: application/sdp Content-Length: xxxx Supported: from-change v=0 c=IN IP4 ua2.example.com c=IN IP4 ua2.example.com a=setup:active t=0 0 m=audio 12000 UDP/TLS/RTP/SAVP 0 a=acfg:1 t=1 Message (9): 200 OK Proxy -> Alice Alice receives the message from her proxy and validates the certificate presented in Message 7. The endpoint now shows Alice that the call as secured. Message (10): RTP+RTCP Alice -> Bob At this point, Alice can also start sending RTP and RTCP to Bob. Message (11): ACK Alice -> Bob Finally, Alice sends the SIP ACK to Bob. 7.2. Basic Message Flow with Connected Identity (RFC 4916) The previous example did not show the use of RFC 4916 for connected identity. The following example does: The first 9 messages of this example are the same as before. However, Messages 10-13, performing the RFC 4916 UPDATE, are new. Message (10): UPDATE Bob -> Proxy Bob sends an RFC 4916 UPDATE towards Alice. This update contains his fingerprint. Bob’s UPDATE contains the same session information that he provided in his 200 OK (Message 8). Note that in principle an UPDATE here can be used to modify session parameters. However, in this case it’s being used solely to confirm the fingerprint. UPDATE sip:alice@ua1.example.com SIP/2.0 Via: SIP/2.0/TLS ua2.example.com;branch=z9hG4bK-0e53sadfkasldkfq To: "Alice" <sip:alice@example.com>;tag=843c7b0b From <sip:bob@example.com>;tag=6418913922105372816 Route: <sip:proxy.example.com;lr> Call-ID: 6076913b1c39c212@REVMTEpG CSeq: 2 UPDATE Contact: <sip:ua2.example.com> Content-Type: application/sdp Content-Length: xxxx Supported: from-change Max-Forwards: 70 v=0 c=- 6418913922105372818 IN IP4 ua2.example.com s=example a=setup:active t=0 0 m=audio 12000 UDP/TLS/RTP/SAVP 0 a=acfg:1 t=1 This shows the UPDATE being relayed to Alice from Bob (and Alice’s proxy). Note that Bob’s proxy has inserted an Identity and Identity-Info header. As above, we only show one element for both proxies for purposes of simplification. Alice verifies the identity provided. (Note: the actual identity signatures here are incorrect and provided merely as examples.) UPDATE sip:alice@ua1.example.com SIP/2.0 Via: SIP/2.0/TLS proxy.example.com;branch=z9hG4bK-0e53sadfkasldkfj Via: SIP/2.0/TLS ua2.example.com;branch=z9hG4bK-0e53sadfkasldkfj To: "Alice" <sip:alice@example.com>;tag=843c7b0b From: <sip:bob@example.com>;tag=6418913922105372816 Call-ID: 6076913b1c39c212@REVMTEpG CSeq: 2 UPDATE Contact: <sip:bob@ua2.example.com> Content-Type: application/sdp Content-Length: xxxx Supported: from-change Max-Forwards: 69 Identity: CyI4+nAkHrH3ntmaxgr01TMxTmtjp7MASwliNRdupRI1vpkXRvZXX1ja9k 3W+v1PDsy32Magzi0M5w6EkXxbgTnPYW0jIoR8HMyY1VT7egt0kk4XrKFC HYWGC10nB2sNsM9CG4hq+YJZTMaSROoMUBhikVIjnQ8ykeD6UXNOyfI= Identity-Info: https://example.com/cert v=0 c=-6418913922105372816 2105372818 IN IP4 ua2.example.com s=example2 z=8 t=0 0 m=audio 12000 UDP/TLS/RTP/SAVP 0 a=acfg:1 t=1 Message (12): 200 OK Alice -> Bob This shows Alice’s 200 OK response to Bob’s UPDATE. Because Bob has merely sent the same session parameters he sent in his 200 OK, Alice can simply replay her view of the session parameters as well. 7.3. Basic Message Flow with STUN Check for NAT Case In the previous examples, the DTLS handshake has already completed by the time Alice receives Bob’s 200 OK (8). Therefore, no STUN check is sent. However, if Alice had a NAT, then Bob’s ClientHello might get blocked by that NAT, in which case Alice would send the STUN check described in Section 6.7.1 upon receiving the 200 OK, as shown below: The messages here are the same as in the first example (for simplicity this example omits an UPDATE), with the following three new messages: Message (5): STUN connectivity-check Alice -> Bob *Section 6.7.1* describes an approach to avoid an SBC interaction issue where the endpoints do not support ICE. Alice (the passive endpoint) sends a STUN connectivity check to Bob. This opens a pinhole in Alice’s NAT/firewall. Message (6): STUN connectivity-check response Bob -> Alice Bob (the active endpoint) sends a response to the STUN connectivity check (Message 3) to Alice. This tells Alice that her connectivity check has succeeded and she can stop the retransmit state machine. Bob retransmits his DTLS ClientHello, which now passes through the pinhole created in Alice’s firewall. At this point, the DTLS handshake proceeds as before. 8. Security Considerations DTLS or TLS media signaled with SIP requires a way to ensure that the communicating peers’ certificates are correct. The standard TLS/DTLS strategy for authenticating the communicating parties is to give the server (and optionally the client) a PKIX [RFC5280] certificate. The client then verifies the certificate and checks that the name in the certificate matches the server’s domain name. This works because there are a relatively small number of servers with well-defined names; a situation that does not usually occur in the VoIP context. The design described in this document is intended to leverage the authenticity of the signaling channel (while not requiring confidentiality). As long as each side of the connection can verify the integrity of the SDP received from the other side, then the DTLS handshake cannot be hijacked via a man-in-the-middle attack. This integrity protection is easily provided by the caller to the callee (see Alice to Bob in Section 7) via the SIP Identity [RFC4474] mechanism. Other mechanisms, such as the S/MIME mechanism described in RFC 3261, or perhaps future mechanisms yet to be defined could also serve this purpose. While this mechanism can still be used without such integrity mechanisms, the security provided is limited to defense against passive attack by intermediaries. An active attack on the signaling plus an active attack on the media plane can allow an attacker to attack the connection (R-SIG-MEDIA in the notation of [RFC5479]). 8.1. Responder Identity SIP Identity does not support signatures in responses. Ideally, Alice would want to know that Bob’s SDP had not been tampered with and who it was from so that Alice’s User Agent could indicate to Alice that there was a secure phone call to Bob. [RFC4916] defines an approach for a UA to supply its identity to its peer UA, and for this identity to be signed by an authentication service. For example, using this approach, Bob sends an answer, then immediately follows up with an UPDATE that includes the fingerprint and uses the SIP Identity mechanism to assert that the message is from Bob@example.com. The downside of this approach is that it requires the extra round trip of the UPDATE. However, it is simple and secure even when not all of the proxies are trusted. In this example, Bob only needs to trust his proxy. Offerers SHOULD support this mechanism and answerers SHOULD use it. In some cases, answerers will not send an UPDATE and in many calls, some media will be sent before the UPDATE is received. In these cases, no integrity is provided for the fingerprint from Bob to Alice. In this approach, an attacker that was on the signaling path could tamper with the fingerprint and insert themselves as a man-in-the-middle on the media. Alice would know that she had a secure call with someone, but would not know if it was with Bob or a man-in-the-middle. Bob would know that an attack was happening. The fact that one side can detect this attack means that in most cases where Alice and Bob both wish for the communications to be encrypted, there is not a problem. Keep in mind that in any of the possible approaches, Bob could always reveal the media that was received to anyone. We are making the assumption that Bob also wants secure communications. In this do nothing case, Bob knows the media has not been tampered with or intercepted by a third party and that it is from Alice@example.com. Alice knows that she is talking to someone and that whoever that is has probably checked that the media is not being intercepted or tampered with. This approach is certainly less than ideal but very usable for many situations. 8.2. SIPS If SIP Identity is not used, but the signaling is protected by SIPS, the security guarantees are weaker. Some security is still provided as long as all proxies are trusted. This provides integrity for the fingerprint in a chain-of-trust security model. Note, however, that if the proxies are not trusted, then the level of security provided is limited. 8.3. S/MIME RFC 3261 [RFC3261] defines an S/MIME security mechanism for SIP that could be used to sign that the fingerprint was from Bob. This would be secure. 8.4. Continuity of Authentication One desirable property of a secure media system is to provide continuity of authentication: being able to ensure cryptographically that you are talking to the same person as before. With DTLS, continuity of authentication is achieved by having each side use the same public key/self-signed certificate for each connection (at least with a given peer entity). It then becomes possible to cache the credential (or its hash) and verify that it is unchanged. Thus, once a single secure connection has been established, an implementation can establish a future secure channel even in the face of future insecure signaling. In order to enable continuity of authentication, implementations SHOULD attempt to keep a constant long-term key. Verifying implementations SHOULD maintain a cache of the key used for each peer identity and alert the user if that key changes. ### 8.5. Short Authentication String An alternative available to Alice and Bob is to use human speech to verify each other’s identity and then to verify each other’s fingerprints also using human speech. Assuming that it is difficult to impersonate another’s speech and seamlessly modify the audio contents of a call, this approach is relatively safe. It would not be effective if other forms of communication were being used such as video or instant messaging. DTLS supports this mode of operation. The minimal secure fingerprint length is around 64 bits. ZRTP [AVT-ZRTP] includes Short Authentication String (SAS) mode in which a unique per-connection bitstring is generated as part of the cryptographic handshake. The SAS can be as short as 25 bits and so is somewhat easier to read. DTLS does not natively support this mode. Based on the level of deployment interest, a TLS extension [RFC5246] could provide support for it. Note that SAS schemes only work well when the endpoints recognize each other’s voices, which is not true in many settings (e.g., call centers). ### 8.6. Limits of Identity Assertions When RFC 4474 is used to bind the media keying material to the SIP signaling, the assurances about the provenance and security of the media are only as good as those for the signaling. There are two important cases to note here: - **RFC 4474** assumes that the proxy with the certificate "example.com" controls the namespace "example.com". Therefore, the RFC 4474 authentication service that is authoritative for a given namespace can control which user is assigned each name. Thus, the authentication service can take an address formerly assigned to Alice and transfer it to Bob. This is an intentional design feature of RFC 4474 and a direct consequence of the SIP namespace architecture. When phone number URIs (e.g., 'sip:+17005551008@chicago.example.com' or 'sip:+17005551008@chicago.example.com;user=phone') are used, there is no structural reason to trust that the domain name is authoritative for a given phone number, although individual proxies and UAs may have private arrangements that allow them to trust other domains. This is a structural issue in that Public Switched Telephone Network (PSTN) elements are trusted to assert their phone number correctly and that there is no real concept of a given entity being authoritative for some number space. In both of these cases, the assurances that DTLS-SRTP provides in terms of data origin integrity and confidentiality are necessarily no better than SIP provides for signaling integrity when RFC 4474 is used. Implementors should therefore take care not to indicate misleading peer identity information in the user interface. That is, if the peer’s identity is sip:+17005551008@chicago.example.com, it is not sufficient to display that the identity of the peer as +17005551008, unless there is some policy that states that the domain "chicago.example.com" is trusted to assert the E.164 numbers it is asserting. In cases where the UA can determine that the peer identity is clearly an E.164 number, it may be less confusing to simply identify the call as encrypted but to an unknown peer. In addition, some middleboxes (back-to-back user agents (B2BUAs) and Session Border Controllers) are known to modify portions of the SIP message that are included in the RFC 4474 signature computation, thus breaking the signature. This sort of man-in-the-middle operation is precisely the sort of message modification that RFC 4474 is intended to detect. In cases where the middlebox is itself permitted to generate valid RFC 4474 signatures (e.g., it is within the same administrative domain as the RFC 4474 authentication service), then it may generate a new signature on the modified message. Alternately, the middlebox may be able to sign with some other identity that it is permitted to assert. Otherwise, the recipient cannot rely on the RFC 4474 Identity assertion and the UA MUST NOT indicate to the user that a secure call has been established to the claimed identity. Implementations that are configured to only establish secure calls SHOULD terminate the call in this case. If SIP Identity or an equivalent mechanism is not used, then only protection against attackers who cannot actively change the signaling is provided. While this is still superior to previous mechanisms, the security provided is inferior to that provided if integrity is provided for the signaling. 8.7. Third-Party Certificates This specification does not depend on the certificates being held by endpoints being independently verifiable (e.g., being issued by a trusted third party). However, there is no limitation on such certificates being used. Aside from the difficulty of obtaining such certificates, it is not clear what identities those certificates would contain -- RFC 3261 specifies a convention for S/MIME certificates that could also be used here, but that has seen only minimal deployment. However, in closed or semi-closed contexts where such a convention can be established, third-party certificates can reduce the reliance on trusting even proxies in the endpoint's domains. 8.8. Perfect Forward Secrecy One concern about the use of a long-term key is that compromise of that key may lead to compromise of past communications. In order to prevent this attack, DTLS supports modes with Perfect Forward Secrecy using Diffie-Hellman and Elliptic-Curve Diffie-Hellman cipher suites. When these modes are in use, the system is secure against such attacks. Note that compromise of a long-term key may still lead to future active attacks. If this is a concern, a backup authentication channel, such as manual fingerprint establishment or a short authentication string, should be used. 9. Acknowledgments Cullen Jennings contributed substantial text and comments to this document. This document benefited from discussions with Francois Audet, Nagendra Modadugu, and Dan Wing. Thanks also for useful comments by Flemming Andreasen, Jonathan Rosenberg, Rohan Mahy, David McGrew, Miguel Garcia, Steffen Fries, Brian Stucker, Robert Gilman, David Oran, and Peter Schneider. We would like to thank Thomas Belling, Guenther Horn, Steffen Fries, Brian Stucker, Francois Audet, Dan Wing, Jari Arkko, and Vesa Lehtovirta for their input regarding traversal of SBCs. 10. References 10.1. Normative References 10.2. Informative References [MMUSIC-SDP] [SIPPING-SRTP] [KEY-TRANSPORT] Wing, D., "DTLS-SRTP Key Transport (KTR)", Work in Progress, March 2009. [MMUSIC-MEDIA] Appendix A. Requirements Analysis [RFC5479] describes security requirements for media keying. This section evaluates this proposal with respect to each requirement. A.1. Forking and Retargeting (R-FORK-RETARGET, R-BEST-SECURE, R-DISTINCT) In this document, the SDP offer (in the INVITE) is simply an advertisement of the capability to do security. This advertisement does not depend on the identity of the communicating peer, so forking and retargeting work when all the endpoints will do SRTP. When a mix of SRTP and non-SRTP endpoints are present, we use the SDP capabilities mechanism currently being defined [MMUSIC-SDP] to transparently negotiate security where possible. Because DTLS establishes a new key for each session, only the entity with which the call is finally established gets the media encryption keys (R3). A.2. Distinct Cryptographic Contexts (R-DISTINCT) DTLS performs a new DTLS handshake with each endpoint, which establishes distinct keys and cryptographic contexts for each endpoint. A.3. Reusage of a Security Context (R-REUSE) DTLS allows sessions to be resumed with the ‘TLS session resumption’ functionality. This feature can be used to lower the amount of cryptographic computation that needs to be done when two peers re-initiate the communication. See [RFC5764] for more on session resumption in this context. A.4. Clipping (R-AVOID-CLIPPING) Because the key establishment occurs in the media plane, media need not be clipped before the receipt of the SDP answer. Note, however, that only confidentiality is provided until the offerer receives the answer: the answerer knows that they are not sending data to an attacker but the offerer cannot know that they are receiving data from the answerer. A.5. Passive Attacks on the Media Path (R-PASS-MEDIA) The public key algorithms used by DTLS cipher suites, such as RSA, Diffie-Hellman, and Elliptic Curve Diffie-Hellman, are secure against passive attacks. A.6. Passive Attacks on the Signaling Path (R-PASS-SIG) DTLS provides protection against passive attacks by adversaries on the signaling path since only a fingerprint is exchanged using SIP signaling. A.7. (R-SIG-MEDIA, R-ACT-ACT) An attacker who controls the media channel but not the signaling channel can perform a MITM attack on the DTLS handshake but this will change the certificates that will cause the fingerprint check to fail. Thus, any successful attack requires that the attacker modify the signaling messages to replace the fingerprints. If RFC 4474 Identity or an equivalent mechanism is used, an attacker who controls the signaling channel at any point between the proxies performing the Identity signatures cannot modify the fingerprints without invalidating the signature. Thus, even an attacker who controls both signaling and media paths cannot successfully attack the media traffic. Note that the channel between the UA and the authentication service MUST be secured and the authentication service MUST verify the UA’s identity in order for this mechanism to be secure. Note that an attacker who controls the authentication service can impersonate the UA using that authentication service. This is an intended feature of SIP Identity -- the authentication service owns the namespace and therefore defines which user has which identity. A.8. Binding to Identifiers (R-ID-BINDING) When an end-to-end mechanism such as SIP-Identity [RFC4474] and SIP-Connected-Identity [RFC4916] or S/MIME are used, they bind the endpoint’s certificate fingerprints to the From: address in the signaling. The fingerprint is covered by the Identity signature. When other mechanisms (e.g., SIPS) are used, then the binding is correspondingly weaker. A.9. Perfect Forward Secrecy (R-PFS) DTLS supports Diffie-Hellman and Elliptic Curve Diffie-Hellman cipher suites that provide PFS. A.10. Algorithm Negotiation (R-COMPUTE) DTLS negotiates cipher suites before performing significant cryptographic computation and therefore supports algorithm negotiation and multiple cipher suites without additional computational expense. A.11. RTP Validity Check (R-RTP-VALID) DTLS packets do not pass the RTP validity check. The first byte of a DTLS packet is the content type and all current DTLS content types have the first two bits set to zero, resulting in a version of zero; thus, failing the first validity check. DTLS packets can also be distinguished from STUN packets. See [RFC5764] for details on demultiplexing. A.12. Third-Party Certificates (R-CERTS, R-EXISTING) Third-party certificates are not required because signaling (e.g., [RFC4474]) is used to authenticate the certificates used by DTLS. However, if the parties share an authentication infrastructure that is compatible with TLS (third-party certificates or shared keys) it can be used. A.13. FIPS 140-2 (R-FIPS) TLS implementations already may be FIPS 140-2 approved and the algorithms used here are consistent with the approval of DTLS and DTLS-SRTP. A.14. Linkage between Keying Exchange and SIP Signaling (R-ASSOC) The signaling exchange is linked to the key management exchange using the fingerprints carried in SIP and the certificates are exchanged in DTLS. A.15. Denial-of-Service Vulnerability (R-DOS) DTLS offers some degree of Denial-of-Service (DoS) protection as a built-in feature (see Section 4.2.1 of [RFC4347]). A.16. Crypto-Agility (R-AGILITY) DTLS allows cipher suites to be negotiated and hence new algorithms can be incrementally deployed. Work on replacing the fixed MD5/SHA-1 key derivation function is ongoing. A.17. Downgrading Protection (R-DOWNGRADE) DTLS provides protection against downgrading attacks since the selection of the offered cipher suites is confirmed in a later stage of the handshake. This protection is efficient unless an adversary is able to break a cipher suite in real-time. RFC 4474 is able to prevent an active attacker on the signaling path from downgrading the call from SRTP to RTP. A.18. Media Security Negotiation (R-NEGOTIATE) DTLS allows a User Agent to negotiate media security parameters for each individual session. A.19. Signaling Protocol Independence (R-OTHER-SIGNALING) The DTLS-SRTP framework does not rely on SIP; every protocol that is capable of exchanging a fingerprint and the media description can be secured. A.20. Media Recording (R-RECORDING) An extension, see [SIPPING-SRTP], has been specified to support media recording that does not require intermediaries to act as an MITM. When media recording is done by intermediaries, then they need to act as an MITM. A.21. Interworking with Intermediaries (R-TRANSCODER) In order to interface with any intermediary that transcodes the media, the transcoder must have access to the keying material and be treated as an endpoint for the purposes of this document. A.22. PSTN Gateway Termination (R-PSTN) The DTLS-SRTP framework allows the media security to terminate at a PSTN gateway. This does not provide end-to-end security, but is consistent with the security goals of this framework because the gateway is authorized to speak for the PSTN namespace. A.23. R-ALLOW-RTP DTLS-SRTP allows RTP media to be received by the calling party until SRTP has been negotiated with the answerer, after which SRTP is preferred over RTP. A.24. R-HERFP The Heterogeneous Error Response Forking Problem (HERFP) is not applicable to DTLS-SRTP since the key exchange protocol will be executed along the media path and hence error messages are communicated along this path and proxies do not need to progress them. Authors’ Addresses Jason Fischl Skype, Inc. 2145 Hamilton Ave. San Jose, CA 95135 USA Phone: +1-415-692-1760 EMail: jason.fischl@skype.net Hannes Tschofenig Nokia Siemens Networks Linnoitustie 6 Espoo, 02600 Finland Phone: +358 (50) 4871445 EMail: Hannes.Tschofenig@gmx.net URI: http://www.tschofenig.priv.at Eric Rescorla RTFM, Inc. 2064 Edgewood Drive Palo Alto, CA 94303 USA EMail: ekr@rtfm.com
Model-based Diagnostics for Propellant Loading Systems Matthew Daigle UC Santa Cruz NASA Ames Research Center Moffett Field, CA 94035 matthew.j.daigle@nasa.gov Michael Foygel Physics Department South Dakota School of Mines and Technology Rapid City, SD 57701 michael.foygel@sdsmt.edu Vadim Smelyanskiy Intelligent Systems Division NASA Ames Research Center Moffett Field, CA 94035 vadim.smelyanskiy@nasa.gov Abstract—The loading of spacecraft propellants is a complex, risky operation. Therefore, diagnostic solutions are necessary to quickly identify when a fault occurs, so that recovery actions can be taken or an abort procedure can be initiated. Model-based diagnosis solutions, established using an in-depth analysis and understanding of the underlying physical processes, offer the advanced capability to quickly detect and isolate faults, identify their severity, and predict their effects on system performance. We develop a physics-based model of a cryogenic propellant loading system, which describes the complex dynamics of liquid hydrogen filling from a storage tank to an external vehicle tank, as well as the influence of different faults on this process. The model takes into account the main physical processes such as highly non-equilibrium condensation and evaporation of the hydrogen vapor, pressurization, and also the dynamics of liquid hydrogen and vapor flows inside the system in the presence of helium gas. Since the model incorporates multiple faults in the system, it provides a suitable framework for model-based diagnostics and prognostics algorithms. Using this model, we analyze the effects of faults on the system, derive symbolic fault signatures for the purposes of fault isolation, and perform fault identification using a particle filter approach. We demonstrate the detection, isolation, and identification of a number of faults using simulation-based experiments. Table of Contents 1 INTRODUCTION ........................................... 1 2 SYSTEM MODELING ........................................ 2 3 DIAGNOSIS APPROACH .................................... 5 4 FAULT DETECTION ..................................... 6 5 FAULT ISOLATION ...................................... 6 6 FAULT IDENTIFICATION ................................. 8 7 RESULTS ........................................ 9 8 CONCLUSIONS ...................................... 10 REFERENCES ........................................ 10 1. INTRODUCTION The loading of cryogenic spacecraft propellants is an inherently risky and unsafe operation, especially in the case of hydrogen [1–4]. Therefore, diagnostic solutions are necessary to quickly identify when a fault occurs, so that recovery actions can be taken or an abort procedure can be initiated before system safety is compromised. Model-based diagnosis approaches enable quick and robust detection, isolation, and identification of faults, because they rely on a detailed model of system behavior under nominal and faulty conditions. Applying a model-based approach requires an in-depth analysis and understanding of the underlying physical processes in order to produce an accurate and reliable system model. However, cryogenic propellant loading involves complex physical processes that are difficult to capture. In this paper, we develop a medium-fidelity, lumped-parameter dynamical model of propellant loading that takes into consideration a variety of complex multi-phase phenomena that govern the storage and transfer of cryogenic propellants, yet is simple enough to allow for physics analysis and numerical simulations of real loading systems [5]. We concentrate on a system of liquid hydrogen (LH2) filling that is functionally representative of the Space Shuttle refueling system. In this system, LH2 is stored on the ground in a spherical, insulated, double-walled storage tank (ST), and is transferred to the external vehicle tank (ET) through a network of pipes and valves. The model takes into account the main physical processes such as highly non-equilibrium condensation and evaporation of the hydrogen vapor, pressurization, and also the dynamics of liquid hydrogen and vapor flows inside the system in the presence of helium gas. Since the model incorporates faults in the system, it provides a suitable framework for model-based diagnostics and prognostics algorithms. We apply a model-based diagnostic approach to the system using a combined qualitative-quantitative diagnosis methodology based on the approach of [6]. Deviations in measured values from model-predicted values are compared to qualitative predictions made using the system model for quick fault isolation. Fault identification is performed using particle filters for joint state-parameter estimation. Using simulation-based experiments, we demonstrate the detection, isolation, and identification of a number of faults. The paper is organized as follows. Section 2 describes the propellant loading system and its physics model. Section 3 overviews the diagnosis approach. Section 4 describes the fault detection methodology. Section 5 discusses fault isolation, and Section 6 develops the fault identification approach. Section 7 verifies the approach with a number of simulation-based experiments. Section 8 concludes the paper. 1 978-1-4244-7351-9/11/$26.00 ©2011 IEEE. 2. System Modeling Model-based diagnosis algorithms utilize a model of the system for the fault detection, isolation, and identification tasks. We advocate a physics-based modeling approach, because an understanding of the physical processes in both the nominal and faulty cases is necessary for successful fault identification. Information on fault severity is necessary in order to make appropriate recovery actions in response to a fault, especially in the propellant loading domain. In this section, we develop the physics model of the LH2 propellant loading system. Since the focus of the paper is on diagnostics, we review the main features of the model, and refer to [4, 5] for additional details. We first summarize the filling protocol, followed by mathematical descriptions of the tank histories. **Filling Protocol** The purpose of the LH2 propellant loading system is to move LH2 from the ST to the ET. Fig. 1 shows a simplified, but functionally equivalent schematic of the system. Initially, the ullages of the tanks are at atmospheric pressure due to the presence of gaseous hydrogen (GH2). Before filling, the tanks are first pressurized. The ST is pressurized to 54.7 psia, then 80.7 psia through the use of the vaporizer, which boils off LH2 from the ST and returns the GH2 to the ullage of the ST. The ET is filled with gaseous helium (GHe) through the prepressurization valve, until it reaches 38.7 psia. The purpose of pressurization is two-fold. First, it limits potential boiling of the propellant by keeping a high vapor pressure in the ullage of the tanks. Second, the pressure difference between the ST and ET drives propellant from the ST to the ET in the absence of a pump. Filling progresses in stages with different filling rates, controlled by the position of the transfer line valve (in reality there are a number of valves between the tanks, but in this paper we consider a simplified representation consisting of a single valve). Slow fill begins first with a low flow rate and chilling of the ET. As the liquid drains out of the ST, its ullage pressure drops, so the vaporizer constantly maintains the ullage pressure to keep LH2 flowing to the ET. The flow through the vaporizer valve is modulated based on the error between the measured ST ullage pressure and the ST pressure set point. As the ET is filled, its ullage volume decreases, and, therefore, its ullage pressure increases. The ullage pressure in the ET is maintained using its vent valve, which opens and closes to maintain the pressure between 38.7 and 41.7 psia. When the ET is 5% full, fast fill begins at a flow rate around 30 kg/s. When the ET is 72% full, the ullage pressure of the ST is reduced to 64.7 psia, reducing the flow rate. When the ET is 85% full, the fill rate is reduced further by partially closing the transfer line valve. When the ET is 98% full, topping begins at a lower flow rate. The ET vent valve is also opened, reducing the ET ullage pressure to 14.7 psia. Finally, at 100% full, topping ends and the tank is then continuously replenished until launch to replace the boil off. During replenish, the fill valve position is modulated to maintain the ET level at 100%. **Tank Modeling** For each tank, we consider three control volumes: the vapor, the liquid, and the vapor film, as shown in Fig. 2. By convention, positive mass/energy flows enter the CV, and negative flows exit the CV. The vapor CV \( (v) \) consists of GH2 (subscript \( v \)) and GHe (subscript \( g \)), and is treated as a mixture of ideal gases with partial densities \( \rho_v \) and pressures \( p_v \), as well as a common temperature \( T_v \), all related to each other by the following equations of state: \[ \rho_v = \rho_v R_v T_v \quad (1) \] \[ p_v = \rho_v R_v T_v \quad (2) \] The liquid CV \( (l) \) is where, far from the surface, the temperature is equal to \( T_l \) and the liquid is treated as incompressible. \( T_l \) is treated as a constant at 20 K. The vapor film CV \( (f) \) separates the liquid and gas phases. It is treated as saturated hydrogen vapor, whose temperature is... equal to that of the liquid/vapor interface, where [1, 4, 7] \[ T_f = T_C \left( \frac{p_e}{p_C} \right)^n, \quad (3) \] with \( p_C = 1.315 \text{ MPa} \), \( T_C = 33.2 \text{ K} \), and \( n = 5 \) [7]. For the liquid CV, the net mass flow is defined by the external mass flow \( J_{le} \) (i.e., the flow across its boundaries other than through the interface), and the interphase (condensation-evaporation) flow \( J_{lv} \) (defined later): \[ \dot{m}_l = J_{le} + J_{lv} \quad (4) \] Similarly, the GH2 and GHe mass conservation for CV (v) is \[ \dot{m}_v = J_{ve} - J_{lv} \quad (5) \] \[ \dot{m}_g = J_{ge}. \quad (6) \] where \( J_{ve} \) and \( J_{ge} \) are the external GH2 and GHe flows. For a given tank volume \( V \), the vapor volume is fully defined by the mass of liquid, since it has a constant density: \[ V = V_v + V_l = V_v + m_l/p_l. \] The energy conservation law for the vapor CV yields: \[ \frac{d(m_vu_v + m_gu_g)}{dt} = \dot{U}_v = \dot{Q}_{ef} - \dot{Q}_{fl} - W - J_{lv}h_{lv} + J_{ve}(h_{ve} + v_{ve}^2/2) + J_{ge}(h_{ge} + v_{ge}^2/2), \quad (8) \] where \( u_{v(g)} = c_{V,v(g)}T_v \) are specific internal energies of the gases, \( \dot{U}_v \) is the net rate of change in internal energy of the mixed gas, \( \dot{Q}_{ve} \) is the net external heat flow into the CV (v) through the tank walls, \( \dot{Q}_{ef} \) is the heat flow lost through the interface, \( W = -p_v dV_v/dt \) is related to the quasi-static power due to convection (solidification) of the CV (v), \( h_{lv}J_{lv} \) is the interphase enthalpy flow (the specific enthalpy \( h_{lv} \) is equal to that of the saturated vapor), \( h_{ve} \) and \( h_{ge} \) are the specific enthalpies of the hydrogen and helium gas entering the CV, and \( v_{ve} \) and \( v_{ge} \) are the velocities of the incoming gases [8]. Here, the kinetic energies associated with both the GH2 and GHe mass flows entering the CV (v) are taken into consideration, because the corresponding velocities \( v_{v(g)} \) are much greater than the one related to interphase flow. The specific enthalpies \( h_{v(g)} = u_{v(g)} + p_{v(g)}/\rho_{v(g)} = u_{v(g)} + R_{v(g)}T_v = c_{P,v(g)}T_v \). Here, \( c_{P,v(g)} = c_{V,v(g)} + R_{v(g)} \) and is the specific heat at constant pressure. The temperature of the mixed gas is then described by \[ T_v = \frac{1}{m_{v,c_v}c_v} (\dot{U}_v - \dot{m}_v c_{V,v} T_v - \dot{m}_g c_{V,g} T_g), \quad (9) \] where \( c_{V,v} \) and \( c_{V,g} \) are the specific heats at constant volume for the vapor and gas, and \( c_V \) is the specific heat at constant volume for the mixed gas. If the film layer is considered negligibly thin so that one can ignore its mass [1], then the energy balance equation for the CV (f) can be written as \[ \dot{Q}_{ef} - \dot{Q}_{fl} + J_{lv}h_{lv} = 0, \quad (10) \] where \( \dot{Q}_{ef} \) is the heat flow from the vapor CV, \( \dot{Q}_{fl} \) is the heat flow to the liquid CV, and \( h_{lv} \) is the enthalpy (heat) of vaporization. Strictly speaking, \( h_{lv} \) depends on the saturated vapor temperature, such that it goes to zero when the surface temperature approaches the critical temperature \( T_C \) [9]. To take this effect into consideration, we use the following simple interpolation formula for \( T_f \leq T_C \): \[ h_{lv}(T_f) = h_{lv}^0 \left( \frac{T_C - T_f}{T_C - T_l} \right)^{1/2}, \quad (11) \] for liquid hydrogen, \( T_C = 33 \text{ K} \) and \( h_{lv}^0 \equiv u_{lv}^0 = 4.5 \times 10^5 \text{ J/kg} \) at \( p = 1 \text{ atm} \) and \( T_l = 20 \text{ K} \) [9]. The heat flow terms may be computed based on the liquid, vapor, and film temperatures, allowing for \( J_{lv} \) to be computed with (10). The heat flows \( \dot{Q}_{fl} \) and \( \dot{Q}_{ef} \) are dominated either by conduction or convection, depending on the relative temperatures of the liquid, vapor, and film [5]. If \( T_f > T_l \) then conduction heat transfer defines \( \dot{Q}_{fl} \), else convection does. If \( T_v > T_f \), then conduction heat transfer defines \( \dot{Q}_{ef} \), else convection does. In the case of convection, we use the following approximations: \[ \dot{Q}_{fl}^\text{cond} = A_f \alpha_{fl}^\text{cond}(T_f - T_l) \quad (12) \] \[ \dot{Q}_{ef}^\text{cond} = A_f \alpha_{ef}^\text{cond}(T_v - T_f), \quad (13) \] where \( A_f \) is the surface area of the interface, and the \( \alpha \) terms are heat transfer coefficients (see [5]). Typically, conduction expressions contain complex integral relations, but here, we use this algebraic approximation that has proven adequate for our system [5]. For convection, we use \[ \dot{Q}_{fl}^\text{conv} = A_f \alpha_{fl}^\text{conv}(T_f - T_l) \quad (14) \] \[ \dot{Q}_{ef}^\text{conv} = A_f \alpha_{ef}^\text{conv}(T_v - T_f). \quad (15) \] Both the liquid and vapor CVs absorb external (e) heat from the tank walls. This heat is transferred by means of convection so that \[ \dot{Q}_{v(l)e} = A_{v(l)} \alpha_{v(l)e} (T_w - T_v(l)) \quad (16) \] where \( A_{v(l)} \) are the internal tank surfaces in contact with vapor (liquid), and \( \alpha_{v(l)e} \) are the convection heat transfer coefficients [5]. The wall temperature \( T_w \) is governed by the heat flow passing through the walls from the environment [1–3]. The temperature \( T_w \) of the tank wall, considered uniform, is defined by the heat exchange rate with the tank surroundings with the effective ambient temperature \( T_a \): \[ \dot{Q}_w = A_w \alpha_w (T_a - T_w) \quad (17) \] where \( A_w \) is the external tank surface area. The wall temperature is governed by the tank energy conservation: \[ m_c \dot{u}_w = \dot{Q}_w - Q_{fl} - \dot{Q}_{v(l)e}. \quad (18) \] Here, the heat transfer coefficients describe natural convection inside and outside the tank walls [1, 10]. The Storage Tank The above equations apply equally well to both the ST and the ET. We denote variables of the ST with a 1 subscript, and variables of the ET with a 2 subscript. For the ST, there is no GHe in the ullage volume, so \( p_{g1} = p_{g1} = 0 \). The external mass flow for the liquid consists of vaporizer flow \( J_{vap} \), transfer line flow \( J_{tr} \), and leak flow \( J_{leak,1} \): \[ J_{le1} = -J_{vap} - J_{tr} - J_{leak,1}. \] (19) \( J_{tr} \) is described by \[ J_{tr} = \lambda_{tr} \sigma_{tr} \alpha_{tr} \sqrt{p_1 - p_2}, \] (20) where \( \lambda_{tr} \) is the valve position (an input), \( \alpha_{tr} \) is the flow coefficient, \( p_1 = p_{tr} + \rho g h_{l1} \) is the total ST pressure where \( h_{l1} \) is the height of the liquid, \( p_2 = p_{ve} \) is the total ET pressure, \( g \) is the acceleration due to gravity and \( \sigma_{tr} \) is a (dimensionless) multiplicative factor describing a transfer line blockage fault. In the vaporizer, a certain amount of LH2 is evaporated and returned to the ST, thus controlling its ullage pressure. We assume that all liquid flow through the vaporizer is converted instantaneously to GH2. The flow is given by \[ J_{vap} = \lambda_{vap} \sigma_{vap} \alpha_{vap} \sqrt{p_{ve} - p_{atm}} \] (21) where \( \lambda_{vap} \) is the vaporizer valve position, \( \alpha_{vap} \) is the flow coefficient, \( p_{vap} \) is the pressure in the vaporizer (close to atmospheric pressure), and \( \sigma_{vap} \) is a multiplicative factor describing the vaporizer valve closure. The vaporizer valve position is controlled by \[ \lambda_{vap} = \min \left( 1, \max \left( 0, 10 \frac{p_{ve} - p_{vap}}{p_{vap}} \right) \right), \] (22) where \( p_{ve} \) is the desired ST pressure. The liquid leak flow is given by \[ J_{leak,1} = A_{leak,1} \alpha_{leak,1} \sqrt{p_1 - p_{atm}}. \] (23) where \( A_{leak,1} \) is the area of the leak hole, \( \alpha_{leak,1} \) is the leak hole flow coefficient, and \( p_{atm} \) is atmospheric pressure. In the vapor CV, \( J_{ve1} = -J_{v,leak,1} \), where \[ J_{v,leak,1} = A_{v,leak,1} \alpha_{v,leak,1} \sqrt{p_{ve} - p_{atm}}. \] (24) Heat leaks constitute the external heat flow term, i.e., \( \dot{Q}_{ve1} = \dot{Q}_{leak,1} \). The External Tank For the ET, the external liquid flow is given by \[ J_{le2} = J_{tr} - J_{leak,2} - J_{boil}, \] (25) where \( J_{leak,2} \) is described similar to that for the ST, and \( J_{boil} = \dot{Q}_{le2}/h_{lw}(T_{lw} - T_{lw}) \) is responsible for intense LH2 evaporation as the ET walls are being initially chilled down during the beginning of the slow fill stage. In the vapor CV, the external flows are given by \[ \begin{align*} J_{ve2} &= -J_{v,vent,2} - J_{v,leak,2} \\ J_{gc2} &= J_{g,pp} - J_{v,vent,2} - J_{g,leak,2}, \end{align*} \] (26), (27) where \( J_{g,pp} \) is the prepressurization flow of GHe, and \[ J_{v(\gamma),vent,2} = \lambda_{vent,2} \sigma_{vent,2} \frac{A_{vent,2} p_{ve} \sqrt{\gamma (p_{ve} + p_{eg} - p_{atm})}}{10^4 K_{vent,2}(p_{ve} + p_{eg})} \] (28) Here, the dimensionless flow coefficient \( K \) (the loss factor) can be found in Schmidt et al. [10] (see Tables 7-2 and 7-3 therein); a dimensionless relative valve position assumes values between \( \lambda_k = 1 \) (fully open) and \( \lambda_k = 0 \) (fully closed) [10]. During filling, the valve opens when the pressure exceeds 41.7 psia and closes when it falls below 38.7 psia. The vapor/gas and heat leaks may be defined as with the ST. Nominal Dynamics Fig. 3 summarizes the major results of the simulation of a nominal loading regime, which are based on the parameters, initial conditions, and filling protocol that are typical for LH2 loading systems. These values are provided in [5]. It can be seen that the LH2 level in the ST drops monotonically (Fig. 3a) as the level in the ET rises (Fig. 3d). The pressure \( p_{ve} \) in the ST (Fig. 3b) is determined by the loading dynamics and controlled by the vaporizer. Once achieved during slow fill, the pressure in the ST is maintained at approximately 80.7 psia up to the start of the reduced-pressure fast fill (see Figs. 3b and 3j), at which point it is maintained at 64.7 psia. Meanwhile, the ET ullage pressure (Fig. 3e) is oscillating due to the cycling of the vent valve that maintains the pressure between the lower and upper thresholds of 38.7 and 41.7 psia. The fluctuations in the ET ullage temperature (Fig. 3f) as well as in the mass flow rates (Figs. 3j and 3h) are driven by the ET pressure oscillations. The LH2 partial pressure in the ET rises due to the continuing hydrogen supply, while the GHe partial pressure drops because the helium is being permanently removed through the vent valve (Fig. 3i). In this case, due to the condensation blocking effect [4], the flow of the condensed vapor in the ET (Fig. 3h) is much smaller than that in the ST (Fig. 3g), because the vapor pressure being maintained approximately equal to the equilibrium pressure of the condensed vapor at the temperature of LH2. The ullage temperature \( T_{ve} \) in the ET (Fig. 3f) increases initially due to the introduction of the GHe during the pressurization stage, then drops from the initial high value due to venting and near-wall boiling that generates relatively cold GH2 during filling. The liquid surface temperature \( T_{lw} \) in the ST increases (Fig. 3c) due to the vapor condensation at the interface. Simultaneously, the ST ullage temperature \( T_{ve} \) increases, mainly because the relatively hot GH2 is supplied by the vaporizer as loading occurs. As a result, the ullage temperature approaches the temperature of LH2 saturated vapor at a pressure close to the final ST ullage pressure of approximately 5 atm (Fig. 3b). 3. Diagnosis Approach We apply a model-based diagnosis approach using the physics model of the LH2 system. In this paper, we consider the problem of single fault diagnosis. The system may be described in the following general form: \[ \begin{align*} \dot{x}(t) &= f(t, x(t), \theta(t), u(t), v(t)) \\ y(t) &= h(t, x(t), \theta(t), u(t), n(t)), \end{align*} \] where \(x(t) \in \mathbb{R}^{n_x}\) is the state vector, \(\theta(t) \in \mathbb{R}^{n_\theta}\) is the parameter vector, \(u(t) \in \mathbb{R}^{n_u}\) is the input vector, \(v(t) \in \mathbb{R}^{n_v}\) is the process noise vector, \(f\) is the state equation, \(y(t) \in \mathbb{R}^{n_y}\) is the output vector, \(n(t) \in \mathbb{R}^{n_n}\) is the measurement noise vector, and \(h\) is the output equation. Measurements are time-varying signals of \(y(t)\) obtained from the system sensors. In the LH2 system, we consider the following measurements for diagnosis: \(V_{l1}, p_1, T_{v1}, V_{l2}, p_2, T_{v2}, J_{fr}, \lambda_{vap},\) and \(\lambda_{vent,2}\). We consider single, abrupt faults, modeled as unexpected step changes in system parameter values. We name faults by the associated parameter and the direction of change, i.e., $\theta^+$ denotes a fault defined as an increase in the value of parameter $\theta$, and $\theta^-$ denotes a fault defined as a decrease in the parameter value. For the LH2 system, we consider liquid and gas leaks, heat leaks, and valve clogging. The liquid and vapor leaks are defined by the equivalent leak areas, nominally zero, so faults are defined as increases in these areas, denoted by $A^+_v, A^+_l$, and $A^-_v, A^-_l$. The heat leaks are defined by the heat leak rate, nominally zero, so faults are increases in these values, denoted by $\dot{Q}^+_v, \dot{Q}^-_v$. The valve clogging faults are described by the $\sigma$ parameters, which are nominally 1, so faults are decreases in these values (0 at a minimum), denoted by $\sigma^-_{fr}, \sigma^-_{vap}$, and $\sigma^-_{vent,2}$. The diagnosis architecture is shown in Fig. 4. The system receives inputs $u(t)$ and produces outputs $y(t)$. The physics simulation runs simultaneously, producing predicted outputs $\hat{y}(t)$, given the inputs $u(t)$. Using statistical methods, the fault detection module decides when a measurement has deviated from its nominal value, triggering fault isolation. Measurement deviations are then used to quickly isolate faults $F$. Fault identification computes, for each fault $f \in F$, the value of the fault parameter that best fits the outputs of the system, and the candidate with the lowest output error is selected as the best candidate. ![Figure 4. Diagnosis architecture.](image) 4. FAULT DETECTION In model-based fault detection, a model of the system provides reference outputs representing nominal system behavior. For each sensor output $y(t)$, we define the residual as $r(t) = y(t) - \hat{y}(t)$, where $\hat{y}(t)$ is the model-predicted output signal. Statistically significant deviations of the actual system outputs from the model-predicted outputs imply the presence of a fault. If the model is accurate, then fault detection thresholds can be small and faults detected quickly. The thresholds are dynamic in that they are defined with respect to nominal behaviors as a function of time. This is favorable to the current practice with such systems, where thresholds are static, preventing the detection of subtle deviations from nominal behavior that indicate faults. We use the Z-test for robust fault detection using a set of sliding windows, as described in [11, 12]. The current mean of a residual signal, $\mu_r(t)$, is estimated over a small window $W_2$: $$\mu_r(t) = \frac{1}{W_2} \sum_{i=t-W_2+1}^{t} r(i).$$ The variance of the nominal residual signal, $\sigma^2_r(t)$, is computed using a large window $W_1$ preceding $W_2$, by a buffer $W_{delay}$, ensuring that $W_1$ does not contain any samples after fault occurrence. The variance is computed using $$\sigma^2_r(t) = \frac{1}{W_1} \sum_{i=t-W_2-W_{delay}-W_1+1}^{t-W_2-W_{delay}} (r(i) - \mu'_r(t))^2,$$ where $$\mu'_r(t) = \frac{1}{W_1} \sum_{i=t-W_2-W_{delay}-W_1+1}^{t-W_2-W_{delay}} r(i).$$ A given confidence level determines the bounds $z^- < 0$ and $z^+ > 0$ for a two-sided Z-test. The fault detection thresholds, $\varepsilon^-_r(t)$ and $\varepsilon^+_r(t)$, are dynamically computed using $$\varepsilon^-_r(t) = z^- \frac{\sigma_r(t)}{\sqrt{W_2}} - E,$$ $$\varepsilon^+_r(t) = z^+ \frac{\sigma_r(t)}{\sqrt{W_2}} + E,$$ where $E$ is a modeling error term. A fault is detected if $\mu_r(t)$ lies outside of the thresholds at time $t$. If $\mu_r(t) < \varepsilon^-_r(t)$, a − symbol for the measurement is used by the fault isolation module, and if $\mu_r(t) > \varepsilon^+_r(t)$, a + symbol is used. Generally, the parameters $W_1, W_2, W_{delay}$, the $z$ bounds, and $E$ must be tuned to optimize performance to minimize both false alarms and missed detections. 5. FAULT ISOLATION We utilize a qualitative diagnosis methodology that isolates faults based on the transients they cause in system behavior, manifesting as deviations in observed measurement values from nominal measurement values [6]. The transients are abstracted using qualitative + (increase), − (decrease), and 0 (no change) values to form fault signatures. Fault signatures represent these measurement deviations from nominal behavior as the immediate (discontinuous) change in magnitude, and the first nonzero derivative change. The fault signatures can be derived automatically from a graph-based representation of the system model, known as a temporal causal graph (TCG) [6]. A TCG captures dynamic system variables as nodes in a graph, and the qualitative relations between them as edges. These edges are labeled with $dt$, representing integration, $+1$, denoting a proportionality, $-1$, denoting an inverse proportionality, and system parameters. Faults that are modeled as parameter changes appear on edges, allowing the qualitative effects of parameter changes to be propagated over the system variables. Propagation to measured variables reveals the qualitative effects of faults on measurements. A partial TCG for the LH2 system, showing some key variables of the ST, is shown in Fig. 5. Variables within dashed boxes are measured. Here, we show only the $\sigma_{vap}$ fault. A forward propagation algorithm may be used to derive the fault signatures. Details may be found in [6], so here, we use the vaporizer valve clogging fault as an example to illustrate the general procedure. According to the TCG, a decrease in $\sigma_{vap}$ will lead to a decrease in $J_{vap}$, and, subsequently, a decrease in $J_{v1}$, and, due to the $-1$ label, an increase in $J_{1}$. The decrease in $J_{v1}$ will lead to a first-order decrease (due to the $dt$ label) in $m_{v1}$ and, subsequently, $p_{v1}$, which is a measured variable. This change then propagates as a decrease in $J_{tr}$, and then towards ET variables. The increase in $J_{1}$ will lead to a first-order increase in $m_{1}$ and $V_{1}$, which is measured, leading to an increase in $J_{tr}$. This conflicts with the previously predicted decrease from the other path with the same derivative order, resulting in an ambiguity denoted with a $\ast$. We can use the simulation and knowledge of the system dynamics to resolve these ambiguities. In this case, we know that the hydrostatic pressure due to the height of the liquid is negligible compared to $p_{v1}$ due to the very low density of LH2. Therefore, we know that the decrease effect will dominate. The propagation continues to all system variables. Fault signatures for the LH2 system are shown in Table 1. Due to the dynamics of the system, all faults appear as smooth changes in the measured values, so only the first change presents useful diagnostic information, hence, we show only the first symbol derived from forward propagation. Recall that the derived symbols represent deviations from nominal behavior, so, for example, the $+$ symbol for $V_{1}$ caused by $A_{v,leak,1}^{+}$ does not necessarily mean that $V_{1}$ increases, rather, it increases with respect to its nominal value, i.e., it decreases at a slower rate. The remaining $\ast$ symbols are for those in which the qualitative effect may be different depending on the state of the system. Note also that this is a hybrid system, i.e., it has continuous dynamics mixed with discrete dynamics due to the valves, and we show only the signatures for the mode where the vent valve is closed. When the vent valve opens, some of the signatures will flip. A systematic framework for dealing with this issue is discussed in detail in [13]. Using the signatures, we can perform diagnosability analysis to determine the effectiveness of the isolation step. We can see that in most cases, the set of signatures produced distinguishes most faults. One exception is the pair $A_{v,leak,1}^{+}$ and $\sigma_{vap}$, which have the same signatures, therefore, fault identification will have to distinguish between them, since quantitatively, they should have different effects on the measured variables. If we measure $J_{vap}$, then the faults can be distinguished, because $\sigma_{vap}$ would produce a decrease in $J_{vap}$, whereas $A_{v,leak,1}^{+}$ would produce an increase. The faults $Q_{leak,2}^{+}$ and $\sigma_{vent,2}$ are similarly indistinguishable. We can also use the signatures to perform measurement selection. The measurement of $\lambda_{vap}$ always has the same signature as $p_{1}$, therefore one of these can be eliminated without loss of diagnosability. However, both quantities are relatively easy to measure, so there is value in keeping them both. $\lambda_{vap}$ is typically more sensitive to faults than $p_{1}$, since $p_{1}$ is controlled by the vaporizer, which may mask faults. Simi- larly, both \( p_2 \) and \( \lambda_{\text{vent},2} \) are not needed. Changes in \( p_2 \) are reflected in changes in the switching frequency of the vent valve, and therefore provide the same information, although changes in the vent valve position can be detected much more easily, again because the control of \( p_2 \) leads to fault masking in that measurement. It is also beneficial to keep as many measurements as possible, because this gives more information for fault identification. Further, the qualitative fault signatures say nothing about fault magnitude. Some faults may not produce large enough changes in some variables for the changes to be detected, therefore, having more measurements helps to alleviate this problem. ### 6. Fault Identification Fault identification is initiated immediately after the initial set of fault candidates is produced after fault detection. Each candidate has its own identification module that updates its estimate at every time step. Identification is performed using the particle filtering algorithm for joint state-parameter estimation [14, 15], which has seen previous application in model-based diagnosis and prognosis algorithms [16–19]. The magnitude of the fault parameter \( \theta \) is estimated along with the system state. The identification module must compute \( p(\mathbf{x}_k, \theta_k | y_{0:k}) \). A general solution to this problem is the particle filter, which may be directly applied to nonlinear systems with non-Gaussian noise terms. Particle filters offer approximate (sub-optimal) solutions to the state estimation problem for systems where optimal solutions are unavailable or intractable [14, 15]. In particle filters, the state distribution is approximated by a set of discrete weighted samples, called particles. As the number of particles is increased, performance increases and the optimal solution is approached. Due to the highly nonlinear dynamics of the LH2 loading system, particle filters are favored over other estimation approaches such as the extended Kalman filter. The particle approximation to the state distribution is given by \[ \{(\mathbf{x}_k^i, \theta_k^i), w_k^i\}_{i=1}^N, \] where \( N \) denotes the number of particles, and for particle \( i \), \( \mathbf{x}_k^i \) denotes the state vector estimate, \( \theta_k^i \) denotes the parameter vector estimate, and \( w_k^i \) denotes the weight. The posterior density is approximated by \[ p(\mathbf{x}_k, \theta_k | y_{0:k}) \approx \sum_{i=1}^N w_k^i \delta(\mathbf{x}_k^i, \theta_k^i) (d\mathbf{x}_k d\theta_k), \] where \( \delta(\mathbf{x}_k^i, \theta_k^i) (d\mathbf{x}_k d\theta_k) \) denotes the Dirac delta function located at \( (\mathbf{x}_k^i, \theta_k^i) \). We use the sampling importance resampling (SIR) particle filter with systematic resampling [14, 20]. The pseudocode for a step of the filter is shown as Algorithm 1. Each particle is propagated forward to time \( k \) by sampling new parameter and state values. The particle weight is assigned using \( y_k \). The weights are then normalized, and then the particles are resampled (see [14]). Note that the parameters \( \theta_k \) evolve by some unknown process that is independent of the state \( \mathbf{x}_k \). The particle filter algorithm requires some type of evolution to the parameters. We use a random walk, i.e., for parameter \( \theta \), \( \theta_k = \theta_{k-1} + \xi_{k-1} \), where \( \xi_{k-1} \) is Gaussian noise. The particles generated with parameter values closest to the true values should match the outputs better, and, therefore, be assigned higher weight, thus allowing the particle filter to converge to the true values. The selected variance of the random walk noise affects both the rate of this convergence and the estimation performance after convergence. Using the simulation, we can determine appropriate values for the random walk variances. Under the single fault assumption, we can run a set of parallel particle filters, one for each consistent fault candidate. This reduces the dimensionality of the estimation task over combined estimation of all fault parameters, and allows the particle filters to be much more efficient. The particle filters are initiated at the point of fault detection, using the model-estimated state at that time point for initialization of the states. The fault parameter estimate starts at its value during nominal operation (e.g., 0 for leak areas). When the fault isolation module reduces the set of candidates \( F \), the identification task continues only for those faults remaining in \( F \). Because diagnosability may be limited, fault identification must also be used to help refine fault candidates. The particle filter for the true fault candidate should estimate the correct fault parameter and track the faulty outputs with low error, whereas the particle filters for the incorrect faults will not track and result in large error. We compute the mean squared output error for each candidate from the point of fault detection to the present time. The candidate with the lowest output error \( e \) is considered to be the true candidate. --- **Algorithm 1 SIR Filter** **Inputs:** \( \{(\mathbf{x}_{k-1}^i, \theta_{k-1}^i), w_{k-1}^i\}_{i=1}^N, u_{k-1} \), \( y_k \) **Outputs:** \( \{(\mathbf{x}_k^i, \theta_k^i), w_k^i\}_{i=1}^N \) **for** \( i = 1 \) to \( N \) **do** \[ \begin{align*} \theta_k^i &\sim p(\theta_k | \theta_{k-1}^i) \\ \mathbf{x}_k^i &\sim p(\mathbf{x}_k | \mathbf{x}_{k-1}^i, \theta_{k-1}^i, u_{k-1} ) \\ w_k^i &\sim p(y_k | \mathbf{x}_k^i, \theta_k^i) \end{align*} \] **end for** \( W = \sum_{i=1}^N w_k^i \) **for** \( i = 1 \) to \( N \) **do** \( w_k^i \leftarrow \frac{w_k^i}{W} \) **end for** \( \{(\mathbf{x}_k^i, \theta_k^i), w_k^i\}_{i=1}^N \leftarrow \text{Resample}(\{(\mathbf{x}_k^i, \theta_k^i), w_k^i\}_{i=1}^N) \) 7. RESULTS We illustrate the diagnosis process with the $A_{v, leak, 1}^+$ fault injected at 2600 s with magnitude $3 \times 10^{-3}$ m$^2$. Note that from diagnosability analysis, the observed signatures will be consistent with both the ST vapor leak fault $A_{v, leak, 1}^+$ and the vaporizer valve clogging fault $\sigma_{vap}$ so the fault identification stage will have to resolve the ambiguity. Relevant measurements are shown in Fig. 6. The diagnoser, running at a sample time of once per second, detects the fault at 2605 s due to an observed decrease in $p_{1}$. The initial list of consistent faults is \{ $A_{v, leak, 1}^+$, $A_{v, leak, 1}^+$, $A_{v, leak, 1}^+$, $A_{v, leak, 1}^+$, $\sigma_{vap}$ \}. At 2608 s, a decrease in $J_{tr}$ is detected, followed by an increase in $\lambda_{vap}$ at 2612 s and a decrease in $T_{v}$ at 2690 s. The candidate set remains the same. At 2703 s, a decrease in $V_{l}$ is detected, which rules out the ET vapor/gas leak fault $A_{v, leak, 2}^+$. At this point, the output error of the $A_{v, leak, 1}^+$ fault is an order of magnitude less than for all other remaining candidates. At 2806 s, a detected increase in $V_{l}$ rules out $A_{v, leak, 1}^+$ and $A_{v, leak, 2}^+$, resulting in the candidate list \{ $A_{v, leak, 1}^+$, $\sigma_{vap}$ \}. By this time, the particle filter for $A_{v, leak, 1}^+$ has also converged on the correct value of the fault magnitude, as shown in Fig. 7. The fault was detected within 5 seconds of its occurrence, and identification confirmed the true fault with correct magnitude within 200 s. It is important to quickly discriminate between a vapor leak in the ST and a clogging of the vaporizer, because the former requires an abort, whereas the system can continue fueling in a safe manner with the latter. As discussed in Section 5, measuring $J_{vap}$ would allow a faster discrimination of these two faults. Diagnosis results over the complete set of faults are shown in Table 2. Here, $\Delta t_{d}$ denotes the time to detect the fault, $\Delta t_{i}$ denotes the time to isolate, taken as the last time at which the candidate set is reduced, $F_{id}$ denotes the output of the fault identification module at the end of the scenario, and $f_{i}$ denotes the final output of the diagnoser, i.e., the identified fault with the lowest error. For the fault identification stage, 50 particles were used per particle filter, which seemed to offer a reasonable trade off between computation time and identification accuracy. Overall, the results are fairly good. In all cases, the correct fault was identified with sufficient accuracy. In some cases, the effects of the faults are very subtle at first, and it takes some time before the changes they produce can be distinguished from the sensor noise. For the vent valve clogging fault, the effects are visible only when the valve is open, so if the fault first appears when the valve is closed, it will take time for the fault to be detected. The $\sigma_{vap}$ fault was detected immediately because the change in $J_{tr}$ was significant. Without this measurement, it would take some time for the fault to be visible in the liquid volumes of the tanks. For some faults, the operation of the vaporizer masks the change in ST pressure, therefore, it is important to monitor the vaporizer valve position in order to obtain a more sensitive ![Figure 6. Predicted and observed outputs for the $A_{v, leak, 1}^+$ fault injected at 2600 s with magnitude $3 \times 10^{-3}$ m$^2$.](image) ![Figure 7. Estimated fault magnitudes and output error for the $A_{v, leak, 1}^+$ fault injected at 2600 s with magnitude $3 \times 10^{-3}$ m$^2$.](image) detection. Changes in the vent valve switching frequency are also easy to observe, but one must wait for the upper pressure threshold to be reached before it can be determined whether it closes early or late. We also observed that faults in the ET are also easy to observe, but one must wait for the upper pressure detection. Changes in the vent valve switching frequency are difficult to observe, but such data can be difficult to acquire. We considered only single faults here, and in the future, we will extend the framework to multiple faults. Sensor faults were not considered here, but can be easily incorporated into a model-based framework by including models of the sensors [12]. Using the physics model for prognostics and loading optimization is also of interest. We would like to validate the approach by using available historical data of faulty situations. Such data can be difficult to find, and, further, there is only a limited capability to inject faults into the system for the purpose of diagnosis algorithm validation, due to the high cost of a fueling operation and the explicit danger that fault injection presents in such a system. Therefore, an accurate simulation with which to validate diagnosis algorithms, such as that used here, is very valuable. ### 8. CONCLUSIONS In this paper, by applying our previously developed physics-based model of a propellant loading system [5], we analyzed the effects of faults, and applied a model-based diagnosis approach to fault detection, isolation, and identification. The detection stage compares observed and model-predicted outputs to detect faults. The isolation stage compares model-predicted fault transients to observed measurements deviations to quickly isolate faults and reduce the complexity of the identification stage. The fault identification stage uses particle filters to estimate the values of fault parameters and resolve isolation ambiguities. The simulation results showed that with such a model-based diagnosis approach, faults can be quickly detected, isolated, and identified, and this knowledge can be used to determine if the system can continue loading safely or if an abort is required. We considered only single faults here, and in the future, we will extend the framework to multiple faults. Sensor faults were not considered here, but can be easily incorporated into a model-based framework by including models of the sensors [12]. Using the physics model for prognostics and loading optimization is also of interest. ### Table 2. Diagnosis Results <table> <thead> <tr> <th>Fault</th> <th>Magnitude</th> <th>$\Delta t_d$</th> <th>$\Delta t_i$</th> <th>$F_{id}$</th> <th>$f^*$</th> </tr> </thead> <tbody> <tr> <td>$A_{v,\text{leak},1}$</td> <td>$1 \times 10^{-3}$ m$^2$</td> <td>17</td> <td>113</td> <td>$A_{v,\text{leak},1} = 9.98 \times 10^{-4}$, $e = 97.1$</td> <td>$A_{v,\text{leak},1} = 9.98 \times 10^{-4}$</td> </tr> <tr> <td>$A_{v,\text{leak},2}$</td> <td>$3 \times 10^{-4}$ m$^2$</td> <td>5</td> <td>206</td> <td>$A_{v,\text{leak},1} = 3.04 \times 10^{-4}$, $e = 27.1$</td> <td>$A_{v,\text{leak},1} = 3.04 \times 10^{-4}$</td> </tr> <tr> <td>$Q_{\text{leak},1}^+$</td> <td>$3 \times 10^4$ W</td> <td>111</td> <td>151</td> <td>$Q_{\text{leak},1}^+ = 2.95 \times 10^4$, $e = 9.44$</td> <td>$Q_{\text{leak},1}^+ = 2.95 \times 10^4$</td> </tr> <tr> <td>$A_{v,\text{leak},1}$</td> <td>$1 \times 10^{-3}$ m$^2$</td> <td>28</td> <td>131</td> <td>$A_{v,\text{leak},1} = 1.10 \times 10^{-3}$, $e = 121$</td> <td>$A_{v,\text{leak},1} = 1.10 \times 10^{-3}$</td> </tr> <tr> <td>$A_{v,\text{leak},2}$</td> <td>$1 \times 10^{-4}$ m$^2$</td> <td>39</td> <td>138</td> <td>$A_{v,\text{leak},1} = 1.30 \times 10^{-4}$, $e = 409$</td> <td>$A_{v,\text{leak},1} = 1.07 \times 10^{-4}$</td> </tr> <tr> <td>$Q_{\text{leak},2}^+$</td> <td>$3 \times 10^4$ W</td> <td>18</td> <td>131</td> <td>$Q_{\text{leak},2}^+ = 4.15 \times 10^4$, $e = 1930$</td> <td>$Q_{\text{leak},2}^+ = 3.19 \times 10^4$</td> </tr> <tr> <td>$\sigma_{\text{tr}}$</td> <td>0.5</td> <td>0</td> <td>13</td> <td>$\sigma_{\text{tr}} = 0.50$, $e = 56.8$</td> <td>$\sigma_{\text{tr}} = 0.50$</td> </tr> <tr> <td>$\sigma_{\text{vap}}$</td> <td>0.5</td> <td>7</td> <td>71</td> <td>$A_{v,\text{leak},1} = 2.14 \times 10^{-3}$, $e = 3.47 \times 10^{0}$</td> <td>$\sigma_{\text{vap}} = 0.50$</td> </tr> <tr> <td>$\sigma_{\text{vent},1}$</td> <td>0.5</td> <td>141</td> <td>152</td> <td>$Q_{\text{leak},2}^+ = 3.21 \times 10^3$, $e = 105$</td> <td>$\sigma_{\text{vent},1} = 0.50$</td> </tr> </tbody> </table> ### REFERENCES
Ecological aspects of viral infection and lysis in the harmful brown tide alga *Aureococcus anophagefferens* Christopher J. Gobler1,*, O. Roger Anderson2, Mary Downes Gastrich2, Steven W. Wilhelm3 1Marine Sciences Research Center, Stony Brook University, Southampton, New York 11968, USA 2Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, New York 10964, USA 3Department of Microbiology, The University of Tennessee, Knoxville, Tennessee 37996, USA ABSTRACT: Although many bloom-forming phytoplankton are susceptible to viral lysis, the persistence of blooms of algal species that are susceptible to viral infection suggests that mechanisms prohibiting or minimizing viral infection and lysis are common. We describe the isolation of viruses capable of lysing the harmful brown tide pelagophyte *Aureococcus anophagefferens* and an investigation of factors which influence the susceptibility of *A. anophagefferens* cells to viral lysis. Nine strains of *A. anophagefferens*-specific viruses (AaV) were isolated from 2 New York estuaries which displayed 3-order of magnitude differences in ambient *A. anophagefferens* cell densities. The host range of AaV was species-specific and AaV was able to lyse 9 of 19 clonal *A. anophagefferens* cultures, suggesting that resistance to viral infection is common among these algal clones. Viral lysis of *A. anophagefferens* cultures was delayed at reduced light intensities, indicating that the low light conditions which prevail during blooms may reduce virally induced mortality of this alga. Some *A. anophagefferens* clones which were resistant to viral infection at 22°C were lysed by AaV at lower temperatures, suggesting that the induction of viral resistance at higher temperatures could allow the proliferation of blooms during summer months. The addition of laboratory propagated viruses to bottle-incubated bloom waters (>10^5 cells ml^-1) from New York and Maryland estuaries resulted in a significant reduction in (p < 0.05), but not complete loss of, *A. anophagefferens* densities, suggesting that a resistant sub-population survived during experiments. In summary, the results demonstrate that clonal resistance, combined with the lower light levels and higher temperatures which are found during brown tides, may allow *A. anophagefferens* to form blooms during summer months. KEY WORDS: *Aureococcus anophagefferens* · Algal viruses · Brown tide · Harmful algal blooms · Viral resistance · Viral infection · Strain specificity INTRODUCTION Harmful algal blooms (HABs) represent a significant threat to fisheries, public health, and economies around the world and have increased in frequency, duration, and distribution in recent decades. Research investigating the causes of HABs has often focused on nutrients or physical factors as stimulative causes of these events (Smayda 1990, Pitcher & Calder 2000, Anderson et al. 2002, Sunda et al. 2006). Recently, some studies have also examined sources of mortality for blooms, such as filter feeding by zooplankton (Colin & Dam 2002, Gobler et al. 2002) or bivalves (Ceratto et al. 2004). However, there have been substantially fewer investigations of the potential role of viruses in regulating HAB dynamics. Viruses are the smallest and most abundant biological entities in the ocean and are a major cause of mortality of marine microorganisms (Wilhelm & Suttle 1999, Suttle 2005). Species-specific lytic viruses have been described for numerous phytoplankton (e.g. Cottrell & Suttle 1991, Suttle & Chan 1995, Bettarel et al. *Email: christopher.gobler@stonybrook.edu* 2005) and many harmful algae (Milligan & Cosper 1994, Nagasaki et al. 1994, Nagasaki & Yamaguchi 1997, 1998, Lawrence et al. 2001, Tarutani et al. 2001, Nagasaki et al. 2003, Baudoux & Brussaard 2005). Many species of HABs, particularly high biomass, ecosystem disruptive algal blooms (EDABs; Sunda et al. 2006), are known to dominate the phytoplankton communities with regard to numbers and biomass (Sunda et al. 2006). Since viruses are most likely to infect and lyse host cells when the ratio of host cells to total suspended particles is maximal (Murray & Jackson 1992, Thingstad & Lignell 1997), it would seem that algal viruses may be highly effective against HABs in general, and EDABs in particular, when host densities are likely to be very high. However, many HABs and EDABs bloom and persist for extended periods of time (i.e. months), without substantial population losses (Gobler et al. 2005). As such, it would seem there are multiple mechanisms, such as intraspecific variability in susceptibility to viral infection (e.g. Nagasaki & Yamaguchi 1998, Nagasaki et al. 2003), which may prohibit viral infection and lysis of bloom populations. However, a clear understanding of these mechanisms has yet to be established. Viruses may influence the dynamics of harmful brown tide blooms caused by the picoplanktonic, pelagophyte *Aureococcus anophagefferens*, which have plagued mid-Atlantic US estuaries, as well as coastal bays in South Africa (Gobler et al. 2003). Electron micrographs of the first observed brown tide event in Rhode Island and subsequent brown tides in New Jersey and New York have revealed the presence of intracellular, icosahedral virus-like particles in *A. anophagefferens* cells (Sieburth et al. 1988, Gastrich et al. 2002, 2004), suggesting that brown tide populations may experience viral infection and lysis. The densities of viruses in the water column during brown tides are elevated (Gobler et al. 2004) and field studies have observed high percentages of virally infected *A. anophagefferens* cells (40%) during the termination of brown tides, suggesting that viruses may be an important source of mortality for blooms (Gastrich et al. 2004). *A. anophagefferens*-specific viruses (AaV) capable of completely lysing cultures of the brown tide alga have been previously isolated from bloom waters in New York estuaries (Milligan & Cosper 1994). Since nothing is known about how AaV may affect brown tide population dynamics, we sought to conduct experiments examining the specificity of AaV, as well as the degree to which light and temperature impact viral lysis of this species. Here, we report the isolation and an ecological characterization of viruses able to infect and lyse the brown tide alga, *Aureococcus anophagefferens*. We isolated AaV from 2 New York estuaries and subsequently conducted experiments examining the susceptibility of 14 species of phytoplankton and 19 *A. anophagefferens* clones to lysis by these viruses. We further examined the effect of light and temperature on viral lysis of *A. anophagefferens* as well as the ability of laboratory-propagated viruses to lyse wild, bloom populations of *A. anophagefferens*. **MATERIALS AND METHODS** **Field collection and isolation of viruses.** We sampled 2 locations within the shallow (mean depth = 1.5 m), well-mixed, barrier island estuaries of Long Island’s south shore monthly in 2002, during the period when brown tides typically occur (April through August). Historically, Quantuck Bay (New York, 40.81°N, 72.62°W) and Bay Shore Cove in western Great South Bay (New York, 40.71°N, 73.23°W) have both been subject to frequent outbreaks of brown tides caused by *Aureococcus anophagefferens* (Gobler et al. 2005). Carboys and experimental flasks used for this project were stored in 10% HCl between sampling dates, and rinsed liberally with distilled-deionized water before use. At each field location, measurements of surface temperature and salinity were obtained with a YSI© 85 probe. Approximately 120 l of surface seawater was collected in polyethylene carboys which were placed in coolers. Samples were transported to the laboratory and processed within 2 h of collection. Whole water was processed to determine concentrations of chlorophyll *a*, and *A. anophagefferens* and viruses at each field station. Chlorophyll samples collected on GFF glass fiber filters were analyzed via standard fluorometric methods (Parsons et al. 1984). *A. anophagefferens* concentrations in samples preserved in 1% glutaraldehyde were enumerated using an enzyme-linked immunoabsorbant assay (ELISA)-based monoclonal antibody labeling technique (Caron et al. 2003). The monoclonal antibody labeling technique was performed using 96-well microtiter plates and converted to abundance using a preserved culture of *A. anophagefferens*. Plates held multiple samples as well as selected dilutions of the samples. Preserved cultures (CCMP 1708) were enumerated microscopically to obtain standard curves. No significant cross-reactions have been observed with a wide variety of co-occurring algae and accurate abundances of *A. anophagefferens* can be obtained to a lower threshold concentration of approximately 10³ cells ml⁻¹. Viruses in 1% glutaraldehyde-preserved seawater were enumerated by epifluorescence microscopy. Specifically, 800 µl aliquots of diluted (8- to 16-fold) sample were collected onto 25 mm diameter, 0.02 µm nominal pore-size Anodisc filters (Whatman) and stained with SYBR Green 1 (Noble & Fuhrman 1998). Viruses in these samples were enumerated manually using a Leica DMRXA epifluorescent microscope equipped with an appropriate optical filter set (excitation wavelength = 450 to 490 nm; emission wavelength = 510 nm) and a 10 × 10 ocular grid (calibrated using a stage micrometer). For all samples, 20 full grids or 200 particles were enumerated to ensure statistical accuracy. These counts provided an estimate of ‘total virus-like particles’ in samples, of which AaV was likely a small fraction. To isolate *Aureococcus anophagefferens*-specific viruses, seawater was filtered (0.2 µm) with acid-cleaned polypropylene filter capsules (0.2 µm pore size; MSI) and acid-washed Teflon tubing (Gobler & Saiñudo-Wilhelmy 2001). The viral size fraction (30 kDa to 0.2 µm) was subsequently concentrated 50–100-fold with an Amicon M12 ultrafiltration system equipped with a S10-Y30 cartridge (30 kDa mixed cellulose membrane; Wilhelm & Porvarin 2001) and then post-filtered (0.2 µm; GV low protein binding filter from Millipore) to ensure the removal of bacteria. A fraction of this volume was microwave sterilized (brought to near-boil and then cooled 3 times) to kill viruses, leaving 2 stocks of viral concentrate: 1 active and 1 inactivated. To screen for the presence of *A. anophagefferens*-specific viruses (AaV) these concentrates were added to *A. anophagefferens* cultures in exponential phase growth. Cultures of *Aureococcus anophagefferens* used to isolate viruses comprised Clone CCMP 1784, originally isolated from Great South Bay, Long Island, New York in 1986 (Cosper et al. 1987) and previously shown to be susceptible to viral infection and lysis (Milligan & Cosper 1994, Gobler et al. 1997). CCMP 1784 and all phytoplankton clones used for this, and other aspects of this study, were obtained from the Provasoli-Guillard Center for Culture of Marine Phytoplankton (CCMP; http://ccmp.bigelow.org). While maintained as unialgal cultures, most cultures were not axenic when received (see Table 1). Epifluorescent microscopic inspection of DAPI-stained preparations confirmed that bacterial abundances in cultures usually remained lower than those of algae until late stationary phase. All cultures were grown in a modified f/2 medium (Guillard & Ryther 1962). Maintenance medium was prepared from filtered (0.2 µm filter capsule, Pall) Atlantic Ocean seawater collected 8 km southeast of the Shinnecock Inlet, near the east end of Long Island, New York and had a salinity of ~30 psu. Media modifications included the addition of 10^{-8} M selenium as selenite, using citric acid (5 × 10^{-6} M) instead of EDTA as a chelator, and using Fe concentrations of 10^{-6} M (Cosper et al. 1993). Semi-complete medium was autoclaved for 45 min and filter-sterilized vitamins were added aseptically after cooling. Cultures were maintained at 22°C on a 14:10 h light-dark cycle, illuminated by a bank of fluorescent lights that provided ~100 µmol quanta m^{-2} s^{-1} to cultures. These conditions approximated temperature and photoperiods found in Long Island estuaries during early summer months when *A. anophagefferens* blooms (Cosper et al. 1989, Milligan & Cosper 1997). Light exposures were close to saturating irradiances determined for *A. anophagefferens* cultures (~120 µmol quanta m^{-2} s^{-1}; Milligan & Cosper 1997). Active and inactivated field isolated virus concentrates were added to exponentially growing *Aureococcus anophagefferens* cultures (~5 × 10^5 cells ml^{-1} initial density) as 10% of culture volume within 24 h of field isolation. Algal biomass was monitored daily using in vivo fluorescence (on a Turner Designs TD-700 fluorometer) and samples were preserved daily with Lugol’s iodine and later enumerated with a hemacytometer on a compound light microscope. Cultures treated with active viral concentrate (which yielded a decrease in biomass while parallel control cultures grew exponentially) were suspected of being infected and lysed by *A. anophagefferens*-specific viruses (AaV). These cultures were filtered through 0.2 µm low-protein binding filters (GV from Millipore), diluted between 1:10^6 and 1:10^9, and reincultured into Clone CCMP 1784 as 10% of culture volume. This process was repeated 10 times before samples were prepared for transmission electron microscopy (TEM) and before experimental work with the viral isolates was conducted. For TEM analysis, duplicate culture samples were pre-fixed in a 2% research TEM-grade buffered (0.2 M cacodylate, pH = 7.8) glutaraldehyde solution. Samples were post-fixed in 2% osmium tetroxide (0.2 M cacodylate, pH = 7.8), dehydrated in a graded series of acetone and embedded in epon. Ultrathin sections, obtained with a diamond knife, were collected on copper grids every 50 to 100 sections to prevent duplication of observations, post-stained with Reynold’s lead citrate and examined with a Philips TEM 201 electron microscope. Individual cells were examined individually in each sample for the presence of virus-like particles (VLPs) using methods previously described by Gastrich et al. (2002). Host specificity experiments. For all experiments, an active virus sample was collected from previously infected *Aureococcus anophagefferens* cultures (Clones 1784 or 1984; ~5 × 10^5 cells ml^{-1} initial density) which had been lysed by viruses to a density of <10^4 cells ml⁻¹. Lysed cultures were filtered through Milli- pore 0.2 µm, low protein binding filters (GV). This active virus filtrate was used within 24 h of collection to infect experimental cultures. Separate aliquots of the filtered viral lysate were heat-killed (see above) and inoculated into parallel control cultures. Active and inactivated viral lysate were added to triplicate labeled infected and control cultures at 10% of the total exper- imental volume. Microscopic quantification of viruses indicated that initial starting concentrations were ~1 × 10⁸ ml⁻¹. Biomass in the experimental and control cul- tures during experiments were monitored as described above. Each negative experiment was repeated at least 3 times to confirm results. Following putative viral lysis of any algal clone, cultures were filtered through 0.2 µm low-protein binding filters (Type GV, Milli- pore), and reinfocculated into the same clone as 10% of culture volume. This process was repeated at least 3 times to confirm results. Effects of light and temperature on virus-mediated lysis of Aureococcus anophagefferens. To determine the extent to which light levels may impact the lysis of A. anophagefferens by AaV, cultures were grown at saturating irradiance (110 µmol quanta m⁻² s⁻¹; Milli- gan & Cosper 1997) as well as at ~3 µmol quanta m⁻² s⁻¹, which is below the half-saturation irradiance (Kₛ) for A. anophagefferens cultures (69 µmol quanta m⁻² s⁻¹; Milligan & Cosper 1997) but similar to the Kₛ observed in field blooms (1.1 to 12.8 µmol quanta m⁻² s⁻¹; Lomas et al. 1996). Since host specificity experi- ments failed to show differences among AaV isolates, experiments at different irradiance values (and other subsequent experiments) were conducted exclusively using viral strain Q711 and A. anophagefferens clone CCMP 1784. Freshly harvested (<24 h post-lysis) AaV were added as 10% of culture volume to exponentially growing A. anophagefferens cultures which began at 5 × 10⁵ cells ml⁻¹. Cultures were monitored daily for flu- orescence and cell density as described above. In addition, the maximum quantum efficiency of Photosystem II (PSII) was estimated from in vivo (Fₐ) and DCMU (3,4-dichlorophenyl-1,1-dimethyleurea)-enhanced in vivo fluorescence (FᵥDCMU) of experimental samples (Parkhill et al. 2001). To avoid diel variations in these estimates, both of these fluorescence characteristics were measured at or close to the same time each day. For this procedure, sub-samples of cultures were dark- adapted for 30 min, mixed, and measured on a TD-700 Turner Designs fluorometer (Kobler et al. 1988, Park- hill et al. 2001). DCMU (in ethanol) was added (final concentration = 10 µM) to samples which were then mixed and measured again fluorometrically once this reading stabilized (approximately 30 s). Maximum quantum efficiency of PSII (Fᵥ/Fₘ) was calculated using: \[ Fᵥ/Fₘ = \frac{(FᵥDCMU - Fₐ)}{FᵥDCMU} \] All readings were blank corrected using 0.2 µm filtered seawater from experimental bottles. DCMU blocks electron transfer between PSI and PSII and yields maximal fluorescence. Previous studies have demonstrated that Fᵥ/Fₘ can be a sensitive diagnostic of photosynthetic efficiency, reaching a maximal value of ~0.7 under nutrient-replete conditions, and decreas- ing to less than half of that under photosynthetic stress (Kobler et al. 1988, Parkhill et al. 2001). To elucidate the impact of temperature on the lysis of Aureococcus anophagefferens by AaV, selected A. anophagefferens clones, which were both susceptible (CCMP 1784, 1851) and resistant (CCMP 1707, 1847, 1854) to viral lysis at 22°C, were grown for 4 genera- tions at temperatures of 5, 10, 15, 20 and 22°C. A. anophagefferens does not grow at temperatures above 25°C (Cosper et al. 1989; this study, data not shown). Freshly harvested (<24 h post-lysis) viruses (Strain Q711) were added as 10% of culture volume to exponentially growing cultures at ~5 × 10⁵ cells ml⁻¹. Cultures were monitored daily for fluorescence and cell density as described above. To quantify the den- sity of bacteria within some A. anophagefferens cultures during these experiments, samples of cultures were preserved with 2% borax-buffer formaldehyde and bacterial concentrations were determined using epiflourescence microscopy after DAPI staining (Porter & Feig 1980). Field experiments. To evaluate the ability of labora- ory propagated AaV to influence the dynamics of wild blooms of Aureococcus anophagefferens, viral addition experiments were established. In 2002, experiments were conducted in late September using water collected from Quantuck Bay, New York (see description in subsection ‘Field collection and iso- lation of viruses’ above). Five parallel experiments were set up, one for each viral strain which was isolated from Quantuck Bay in 2002 (Table 1). For each exper- iment, 5 ml of freshly isolated AaV (see above) was added to 45 ml of bay water in triplicate, polycarbon- ate, 50 ml flasks. Triplicate heat-killed controls were also established for each viral strain. To ensure nitro- gen- and phosphorus-replete growth during incuba- tions, a filter-sterilized (0.2 µm) nutrient solution was added to all flasks to yield final concentrations of 20 µM nitrate and 1.25 µM orthophosphate. Exper- imental flasks were incubated for 72 h, under 2 layers of neutral density screening (66% light attenuation), in eastern Shinnecock Bay at the Stony Brook– Southampton Marine Station (5 km from and contigu- ous with Quantuck Bay), allowing for simulation of ambient light and temperature conditions of Quan- tuck Bay during experiments (Gobler et al. 2002). After 72 h, aliquots from each flask were removed, preserved and enumerated for densities of *Aureococcus anophagefferens* (see description in subsection 'Field collection and isolation of viruses'). Differences in *A*. *anophagefferens* cell densities within each active and inactivated virus strain addition were evaluated via a Student's *t*-test (Sokal & Rohlf 1995). During June of 2003, an experiment was conducted in Public Landing, Chincoteague Bay, Maryland (38.15° N, 75.29° W) which has experienced frequent and intense brown tides during the past decade (Gobler et al. 2005). For this experiment, there were 3 sets of triplicate flasks: A nutrient only control (nutrients, but no viruses, added), an active viral addition (with nutrients added), and an inactivated viral addition (with nutrients added). Virus additions were 25 ml of freshly propagated and filtered AaV Strain Q711 which was unamended or heat-killed, and added to 225 ml of bay water in 275 ml polycarbonate flasks. All flasks had nutrients added as described above. Flasks were incubated *in situ* in Public Landing under 2 layers of neutral density screening (66% light attenuation), allowing for simulation of ambient light and temperature conditions. After 72 h, aliquots from each flask were removed, preserved and enumerated for densities of *Aureococcus anophagefferens* (see description in subsection 'Field collection and isolation of viruses'). Differences in *A*. *anophagefferens* cell densities within active, inactivated, and control treatments during the Chincoteague Bay experiment were evaluated by 1-way ANOVA, followed by Tukey's multiple comparisons test (Sokal & Rohlf 1995). ### RESULTS #### Initial isolation and propagation of AaV Great South Bay and Quantuck Bay differed in their respective algal and viral densities during 2002, with Quantuck hosting significantly higher levels of chlorophyll *a* (*chl a*) (mean ± SE = 17 ± 3.5 µg l⁻¹), *Aureococcus anophagefferens* cell densities (1.8 ± 1.3 × 10⁵ cells ml⁻¹), and total VLPs (2.4 ± 0.5 × 10⁸ ml⁻¹) compared to Great South Bay (5.4 ± 3.4 µg *chl a* l⁻¹, 9.2 ± 2.8 × 10³ *A*. *anophagefferens* cells ml⁻¹, and 1.2 ± 0.3 × 10⁸ VLPs ml⁻¹; Table 1; *p* < 0.05 for all; *t*-tests). Despite these differences, there was near equal success in isolating *A. anophagefferens*-specific viruses (AaV) from the 2 sites, as viruses were isolated from Quantuck Bay on 5 of 6 dates, and from Great South Bay on 4 of 6 dates (Table 1). Viruses were not isolated from either site in April, and none were isolated during August in Great South Bay. There were multiple lines of evidence to confirm the isolation of AaV from each embayment. After the addition of active viral concentrate from the field, *Aureococcus anophagefferens* cultures did not grow and decreased to undetectable cell densities in less than 1 wk (Fig. 1). By contrast, the heat-killed viral concentra- ### Table 1. Physical and biological conditions in Quantuck Bay and Great South Bay, concentration factor (CF) used to isolate viruses, success of isolating *Aureococcus anophagefferens*-specific viruses (AaV isolated), and AaV strain isolated. <table> <thead> <tr> <th>Date</th> <th>T</th> <th>S</th> <th>Chl a (µg l⁻¹)</th> <th>Cells (ml⁻¹ × 10³)</th> <th>Viruses (ml⁻¹ × 10⁸)</th> <th>CF</th> <th>AaV isolated</th> <th>AaV isolated strain</th> </tr> </thead> <tbody> <tr> <td><strong>Quantuck Bay</strong></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>19 Apr</td> <td>20</td> <td>29</td> <td>18 ± 0.96</td> <td>10 ± 3.5</td> <td>2.6 ± 0.71</td> <td>120</td> <td>–</td> <td>–</td> </tr> <tr> <td>23 May</td> <td>16</td> <td>28</td> <td>5.5 ± 0.73</td> <td>37 ± 1.5</td> <td>1.0 ± 0.19</td> <td>100</td> <td>+</td> <td>Q523</td> </tr> <tr> <td>04 Jun</td> <td>20</td> <td>29</td> <td>9.8 ± 3.3</td> <td>68 ± 1.9</td> <td>1.6 ± 0.471</td> <td>80</td> <td>+</td> <td>Q64</td> </tr> <tr> <td>18 Jun</td> <td>21</td> <td>26</td> <td>19 ± 3.0</td> <td>370 ± 36</td> <td>3.8 ± 1.3</td> <td>100</td> <td>+</td> <td>Q618</td> </tr> <tr> <td>11 Jul</td> <td>24</td> <td>30</td> <td>30 ± 5.0</td> <td>110 ± 19</td> <td>3.9 ± 0.92</td> <td>100</td> <td>+</td> <td>Q711</td> </tr> <tr> <td>08 Aug</td> <td>24</td> <td>29</td> <td>21.5 ± 3.2</td> <td>19 ± 0.55</td> <td>1.6 ± 0.14</td> <td>100</td> <td>+</td> <td>Q88</td> </tr> <tr> <td><strong>Great South Bay</strong></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>24 Apr</td> <td>14</td> <td>29</td> <td>5.3 ± 0.66</td> <td>1.5 ± 0.27</td> <td>0.66 ± 0.12</td> <td>40</td> <td>–</td> <td>–</td> </tr> <tr> <td>21 May</td> <td>16</td> <td>27</td> <td>5.3 ± 1.3</td> <td>18 ± 0.82</td> <td>1.3 ± 0.45</td> <td>95</td> <td>+</td> <td>B512</td> </tr> <tr> <td>06 Jun</td> <td>22</td> <td>27</td> <td>7.1 ± 1.6</td> <td>10 ± 0.27</td> <td>1.6 ± 0.76</td> <td>95</td> <td>+</td> <td>B66</td> </tr> <tr> <td>20 Jun</td> <td>23</td> <td>28</td> <td>4.6 ± 2.1</td> <td>17 ± 2.4</td> <td>2.2 ± 0.15</td> <td>105</td> <td>+</td> <td>B620</td> </tr> <tr> <td>09 Jul</td> <td>26</td> <td>29</td> <td>4.5 ± 0.79</td> <td>4.3 ± 2.0</td> <td>0.79 ± 0.28</td> <td>90</td> <td>+</td> <td>B79</td> </tr> <tr> <td>06 Aug</td> <td>28</td> <td>30</td> <td>5.6 ± 0.66</td> <td>5.0 ± 0.27</td> <td>0.66 ± 0.16</td> <td>110</td> <td>–</td> <td>–</td> </tr> </tbody> </table> ![Fig. 1. *Aureococcus anophagefferens*. Mean (±SD, n = 3) growth of clone CCMP 1784 following addition of heat-killed (■) and active (○) viral concentrates isolated from Quantuck Bay in 2002](image-url) trate fostered standard logarithmic growth in *A. anophagefferens* cultures (Fig. 1). Following putative viral lysis of an *A. anophagefferens* culture, viral filtrate of lysed cultures were filtered through 0.1 µm filters, diluted between 1:10^6 and 1:10^9, and reinoculated in *A. anophagefferens* cultures. This yielded the complete loss of cells from cultures in the lower dilutions (e.g. Fig. 1). After propagation of culture filtrate through *A. anophagefferens* cultures for 10 generations, TEMs of cultures infected with viruses at 48 h displayed inclusions of virus-like particles which were nearly identical to those previously reported for wild blooms (Fig. 2A; Sieburth et al. 1988, Gastrich et al. 2002, 2004) and laboratory cultures (Gastrich et al. 1998). Moreover, individual VLPs external to the cells observed with TEM resembled the morphology and size of those in the cells (Fig. 2B). **Host range of AaV** Each of the 9 lines of viruses was propagated through the axenic *Aureococcus anophagefferens* strain CCMP 1984 for 6 mo and was subsequently used to establish the host range of the viruses. None of the 9 strains of AaV was capable of lysing any of the 14 phytoplankton tested besides *A. anophagefferens* (Table 2), including the 3 pelagophytes available from CCMP: *Pelagomonas* spp. (CCMP 1864), *Pelagococcus subviridis* (CCMP 1429) and *Aureoumbra lagunensis* (CCMP 1681; Table 2). Of the 19 clones of *Aureococcus anophagefferens* available from CCMP, 7 were completely lysed by the 9 strains of viruses isolated in 2002, including both axenic clones (CCMP 1982, 1984; Table 2). Two of the *A. anophagefferens* clones (CCMP 1850 and 1852) were partially, but not fully, lysable by AaV, typically displaying at least a 50% reduction in, but not full loss of, algal biomass relative to control cultures within 1 wk of viral inoculation (Table 2). TEM analysis indicated that these 2 strains showed a significantly lower percentage of infected cells 2 d after inoculation with viruses (1.5 ± 0.7%) compared to a fully lysable culture (CCMP 1851; 44 ± 18%; t-test; p < 0.05). Moreover, an extended incubation of one of these cultures (>1 mo; CCMP 1850) yielded a recovery in cell densities to levels beyond the initial inoculation. These ‘recovered’ cultures were not subsequently susceptible to lysis by AaV. There was no variability in the ability of the 9 different isolated viral strains (Table 1) to infect different clones of *A. anophagefferens*. **Impact of reduced light levels on viral lysis of *Aureococcus anophagefferens*** Replicated incubations of *Aureococcus anophagefferens* at high and low light levels demonstrated that cultures incubated at lower light levels experienced a delay in viral lysis compared to cultures incubated at high light (Fig. 3). *A. anophagefferens* cultures inoculated with viruses incubated under high light conditions (110 µmol quanta m^{-2} s^{-1}) typically lysed within 3 d, reaching cell densities <10^4 cells ml^{-1} (Fig. 3). Control cultures grown under low light (~3 µmol quanta m^{-2} s^{-1}) did not change appreciably in cell densities, while those inoculated with viruses took 7 d to decrease below 10^4 cells ml^{-1} (Fig. 3A). During experiments, the photosynthetic efficiency of all cultures was 0.48 ± 0.06 at the beginning and increased to ~0.6 within 24 h of inoculation into new media, regardless of light levels (Fig. 3B). After this initial increase, photosynthetic efficiency of non-infected cultures at high and low light decreased each day until the end of the experiment (Fig. 3B). In contrast, high light infected cultures displayed a significant increase in photosynthetic efficiency compared to the higher light control on Days 2 and 3 (ANOVA, p < 0.05; Fig. 3B), whereas low light cultures displayed higher photosynthetic efficiency compared to their control cultures on Days 4 and 5 (ANOVA, p < 0.05; Fig. 3B). By the end of the experiment, the photosynthetic efficiency of both infected cultures had decreased substantially, becoming lower than control cultures (Fig. 3B). Table 2. Host-specificity of Aureococcus anophagefferens viruses (AaV). CCMP: Provasoli-Guillard Center for Culture of Marine Phytoplankton. Origin, isolation date, and axenic condition all refer to host phytoplankton. Lysis denotes ability of AaV to infect and lyse each species or strain. <table> <thead> <tr> <th>Genus, species</th> <th>Algal class</th> <th>CCMP clone</th> <th>Origin</th> <th>Isolation date</th> <th>Axenic</th> <th>Lysis</th> </tr> </thead> <tbody> <tr> <td>Phaeodactylum tricornutum</td> <td>Bacillariophyceae</td> <td>630</td> <td>Cape Cod Bay, MA</td> <td>1972</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Dunaliella tertiolecta</td> <td>Chlorophyceae</td> <td>1320</td> <td>Unknown</td> <td>Unknown</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Thalassiosira pseudonana</td> <td>Coccolithophyceae</td> <td>1335</td> <td>Long Island Sound, NY</td> <td>1956</td> <td>No</td> <td>No</td> </tr> <tr> <td>Rhodomonas salina</td> <td>Cryptophyceae</td> <td>1319</td> <td>Great South Bay, NY</td> <td>1985</td> <td>No</td> <td>No</td> </tr> <tr> <td>Prorocentrum minimum</td> <td>Dinophyceae</td> <td>696</td> <td>Northwest Atlantic</td> <td>1978</td> <td>No</td> <td>No</td> </tr> <tr> <td>Synechococcus bacillaris</td> <td>Cyanophyceae</td> <td>1333</td> <td>Long Island Sound, NY</td> <td>1958</td> <td>No</td> <td>No</td> </tr> <tr> <td>Emiliania huxleyi</td> <td>Prymnesiophyceae</td> <td>375</td> <td>Sargasso Sea</td> <td>1967</td> <td>No</td> <td>No</td> </tr> <tr> <td>Pyrococcus provosolii</td> <td>Prasinophyceae</td> <td>1203</td> <td>Northwest Atlantic</td> <td>1978</td> <td>No</td> <td>No</td> </tr> <tr> <td>Tetraselmis sp.</td> <td>Prasinophyceae</td> <td>896</td> <td>Falmouth Great Pond, MA</td> <td>1954</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Chlorella autotrophica</td> <td>Trebouxio phyceae</td> <td>243</td> <td>Long Island Sound, NY</td> <td>1952</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Nannochloris atomus</td> <td>Trebouxio phyceae</td> <td>509</td> <td>Great South Bay, NY</td> <td>1952</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Pelagomonas sp.</td> <td>Pelagophyceae</td> <td>1864</td> <td>Sargasso Sea</td> <td>1999</td> <td>No</td> <td>No</td> </tr> <tr> <td>Pelagococcus subviridis</td> <td>Pelagophyceae</td> <td>1429</td> <td>Baltic Sea</td> <td>Unknown</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Aureoumbra lagunensis</td> <td>Pelagophyceae</td> <td>1681</td> <td>Laguna Madre, TX</td> <td>1991</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1706</td> <td>West Neck Bay, NY</td> <td>Oct 1995</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1707</td> <td>West Neck Bay, NY</td> <td>Oct 1995</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1708</td> <td>West Neck Bay, NY</td> <td>Jun 1995</td> <td>No</td> <td>Yes</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1784</td> <td>Great South Bay, NY</td> <td>Jun 1986</td> <td>No</td> <td>Yes</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1785</td> <td>Great South Bay, NY</td> <td>Jun 1986</td> <td>No</td> <td>Yes</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1789</td> <td>Great South Bay, NY</td> <td>Oct 1995</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1790</td> <td>Great South Bay, NY</td> <td>Oct 1995</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1791</td> <td>Great South Bay, NY</td> <td>Oct 1995</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1794</td> <td>Barnegat Bay, NJ</td> <td>Jul 1997</td> <td>No</td> <td>Yes</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1847</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1848</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1849</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1850</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1851</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>Yes</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1852</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1853</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1854</td> <td>Great South Bay, NY</td> <td>May 1998</td> <td>No</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1982</td> <td>Great South Bay, NY</td> <td>Jun 1986</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Aureococcus anophagefferens</td> <td>Pelagophyceae</td> <td>1984</td> <td>Great South Bay, NY</td> <td>Jun 1986</td> <td>Yes</td> <td>No</td> </tr> </tbody> </table> Impact of temperature on viral lysis of *Aureococcus anophagefferens* Temperature had a substantial impact on the ability of AaV to lyse some clones of *Aureococcus anophagefferens*. All clones of *A. anophagefferens* examined which were susceptible to AaV at the standard incubation temperature 22°C (CCMP 1982, 1784, 1851) were equally susceptible to viral lysis over the range of temperatures examined (10 to 22°C). However, 2 clones of *A. anophagefferens* which were resistant to AaV at 22°C were lysed by the viruses at lower temperatures (Fig. 4). Specifically, although clones 1854 and 1707 were both resistant to viral lysis at 22°C, clone 1854 experienced viral lysis at all incubation temperatures below 22°C (Fig. 4B), whereas clone 1708 was lysable at 10 and 5°C, but not at 20 and 15°C (Fig. 4A). The ability of AaV to lyse other strains of *A. anophagefferens* (clones 1847 and 1850) was not affected by incubation temperature. ![Fig. 4. *Aureococcus anophagefferens*. Mean (±SD, n = 3) cell densities of clones grown with active (open symbols) and inactive (filled symbols) cultures. (A) Clone CCMP 1707 grown at 22°C ( ), 10°C ( ), and 5°C ( ); (B) Clone CCMP 1854 grown at 22°C ( ), 20°C ( ), and 15°C ( ). CCMP 1707 was not lysed at 20 and 15°C, whereas CCMP 1854 was lysed at all tested temperatures below 22°C (20, 15, 10°C); only 3 temperature treatments are shown per clone for clarity.](image) Infection of natural populations of *Aureococcus anophagefferens* by laboratory-cultured virus During late September 2002, the brown tide bloom in Quantuck Bay returned and achieved densities of $5 \times 10^5$ cells ml$^{-1}$ (Table 1). The addition of 3 viral strains isolated from Quantuck Bay to the bloom water, contained in flasks placed in situ, did not significantly alter the densities of *Aureococcus anophagefferens* (Fig. 5), although there was often substantial variability among replicate treatments. However, the addition of virus strains Q618 and Q711 resulted in significant (60 and 40%, respectively) decreases in *A. anophagefferens* cell densities compared to the heat-killed control additions ($p < 0.05$; $t$-test; Fig. 5). During June 2003, a substantial brown tide bloom occurred in Chincoteague Bay ($>3 \times 10^5$ cells ml$^{-1}$). The experimental addition of active AaV strain Q711 to this bloom water yielded *A. anophagefferens* cell densities which were significantly (~70%) lower than initial and control treatment densities ($p < 0.01$; Tukey’s test; Fig. 6). **DISCUSSION** While virus-mediated cell lysis is often cited as a primary mortality mechanism for marine microbes in general (Wilhelm & Suttle 1999, Wommack & Colwell 2000, Suttle 2005), and harmful algae in particular (Nagasaki et al. 1994, Nagasaki & Yamaguchi 1998, Tarutani et al. 2000, 2001, Lawrence et al. 2001, Thyhrhaug et al. 2003, Brussaard 2004, Gastrich et al. 2004, Zingone et al. 2006), the occurrence of algal blooms indicates that rates of viral lysis are (at least upon bloom initiation) lower than phytoplankton growth rates. During this study, the resistance of some *Aureococcus anophagefferens* clones at all tempera- ![Fig. 5. *Aureococcus anophagefferens*. Mean (±SD, n = 3) initial cell densities in Quantuck Bay, September 2002, and 72 h after addition of active or inactivated viral isolates Q523, Q64, Q618, Q711, and Q88.](image) tures, and other clones at higher temperatures, suggests a novel mechanism whereby brown tides are likely able to progress in the absence of viral mortality. These results, combined with experiments demonstrating that viral lysis is delayed at lower light levels and with field experiments indicating that laboratory-propagated viruses can lyse a portion of, but not all, *A. anophagefferens* cells, provide a new understanding of the role of AaV in brown tide bloom dynamics. To date, there has been a degree of uncertainty regarding the morphology of AaV as 2 distinct viral morpho-types have been reported. Intracellular viruses within field populations of *Aureococcus anophagefferens* (Sieburth et al. 1988; Gastrich et al. 1998, 2002, 2004) and recently isolated viruses from NY and NJ waters (Gastrich et al. 2004) have been shown to be icosahedral and 100 to 140 nm in diameter. In contrast, the first ever isolated AaV were shown to resemble 80 nm, tailed-phages (Milligan & Cosper 1994, Garry et al. 1998) and have since been suspected of being a bacteriophage which had infected co-occurring bacteria in *A. anophagefferens* cultures. During the present study, viruses both within and outside *A. anophagefferens* cells strongly resembled the former morphology (~100 to 140 nm icosahedrals; Fig. 2) which has consistently been found within field populations of this species (Sieburth et al. 1988, Gastrich et al. 1998, 2004). Moreover, our dilution of field isolated viral concentrates to extinction, combined with the ability of our 0.1 µm filtered virus lysate to infect and lyse axenic cultures, strongly implicate the action of a lytic virus on *A. anophagefferens* cells and not the action of, or interaction with, bacteria. Fig. 6. *Aureococcus anophagefferens* Mean (±SD, n = 3) initial cell densities in Chincoteague Bay, June 2003, and 72 h after addition of nutrients and active or inactivated viral isolates Q711, and Q88, or nutrients only (‘Control’). Although some algal viruses (specifically cyanophage) can infect multiple genera of phytoplankton (Suttle & Chan 1993, Sullivan et al. 2003), the majority are species-, and often clone-specific (Nagasaki & Yamaguchi 1998, Tarutani et al. 2000, Schroeder et al. 2002). This was the case with AaV, as these viruses were unable to infect even the alga most genetically similar to *Aureococcus anophagefferens*, the Texas brown tide species, *Aureoumbra lagunensis* (DeYoe et al. 1995). Among *A. anophagefferens* clones available, AaV was capable of lysing only a fraction (9) of the 19 clones available (Table 2). Prior analysis of the genetic diversity of *A. anophagefferens* revealed identical base pair sequences for the small subunit of the rRNA gene, the small subunit of the RuBISCo gene, and the non-encoding spacer regions of RuBISCo within 14 clones of *A. anophagefferens* isolated over a 12 yr period (1986 to 1998) from 3 different estuaries (Peconic Bay, Great South Bay and Barnegat Bay) in 2 states (New York and New Jersey; Bailey & Andersen 1999). These identical sequences led Bailey and Andersen (1999) to conclude that *A. anophagefferens* field populations are not genetically diverse and do not contain varieties or cryptic species. Despite these findings, our examination of viral infection of these same clones (plus 5 addition clones) has documented 3 distinct responses to viruses: susceptible to lysis, resistant to lysis and partially resistant to lysis by AaV. This could indicate that there is a larger degree of genetic diversity among *A. anophagefferens* clones than originally described (Bailey & Andersen 1999), potentially associated with cell-surface receptor sites. It is also possible that the ability of AaV to absolutely lyse some individual *Aureococcus anophagefferens* cultures may be influenced by the precise clonal nature of the cultures. Two of the algal clones examined during this study were partially, but not completely, lysed by AaV (Table 2), and one of these cultures (CCMP 1850) displayed robust growth several weeks after an initial decline in biomass. This result could reflect the development of resistance in culture during this experiment. Alternatively, it may also reflect the existence of both susceptible and resistant strains of *A. anophagefferens* in the same purported monoclonal culture. This hypothesis is partially supported by the low percentage of infected cells in semi-resistant cultures compared to fully susceptible cultures (1.5 ± 0.7 vs. 44 ± 18%) 48 h after AaV was added to both culture types. Viral lysis of *Aureococcus anophagefferens* is delayed at low irradiances (Fig. 3). Previous research has suggested that the energy used for host replication of algal viruses is often derived from photosynthetic pathways (MacKenzie & Haselkorn 1972, Sherman 1976, Juneau et al. 2003, Lindell et al. 2005). As such, the delay in viral lysis of *A. anophagefferens* at lower light levels suggests that at least some of the energy derived for AaV synthesis is derived from photosynthesis. This hypothesis is supported by observation that the photosynthetic efficiency of virally infected cultures was, at times, higher than that of control cultures, regardless of light levels (Fig. 3B). Furthermore, TEM observations of viral-infected cells have consistently shown that the chloroplast of A. anophagefferens persists during the production of intracellular viral-like particles, even though other membranous organelles are degraded or absent (Fig. 2A; Gastrich et al. 2002, 2004), indicating potential for cells to photosynthesize, even after viral infection. However, since control cultures growing at low light and with inactivated viruses did not grow substantially, we cannot fully discount the possibility that delayed lysis under low light may be due to reduced host growth rates, rather than low light. The link between viral lysis of Aureococcus anophagefferens and its photosynthesis has 2 important implications for the occurrence of brown tide blooms. First, since light is highly attenuated during brown tides due to scattering by high densities (10^9 ml−1) of these small-sized cells (2 to 3 µm; Gobler et al. 2005), A. anophagefferens photosynthetic rates may be reduced during blooms. If this is the case, rates of viral lysis during brown tides may decrease as blooms become denser and light levels decrease, even though some of the cells may be infected by the viruses. A second implication of the link between photosynthesis and viral lysis of brown tide is associated with the ability of A. anophagefferens to growth heterotrophically (Berg et al. 2002, Mullholland et al. 2002, Gobler et al. 2005). Our results suggest that a strong reliance on external organic carbon sources rather than cellular photosynthesis for growth by A. anophagefferens could minimize viral replication and thus mortality losses due to viral lysis during brown tides, further promoting bloom proliferation. In this respect, it is important to note, once again, that TEM has indicated that during VLP proliferation within the cell, the chondriome is degraded or absent (Fig. 2A; Gastrich et al. 2002, 2004). Hence, there is little likelihood that substantial, heterotrophic-based respiratory energy would be available to support viral particle production during advanced stages of viral infection. Indeed, most of the energy for viral production may come from chloroplast-captured light energy. Two clones of Aureococcus anophagefferens that were resistant to viral lysis at 22°C were lysed by AaV at lower temperatures (Fig. 4). This result is somewhat consistent with the findings of Nagasaki & Yamaguchi (1998), who also found strain-specific resistance to viral infection at higher temperature, in their case 30°C. The observed impact of temperature on viral lysis of A. anophagefferens could have important implications for brown tide dynamics. A. anophagefferens blooms most commonly initiate during summer months in mid-Atlantic US as estuarine temperatures increase from cool spring temperatures (<10°C) to >20°C and often end in the fall when temperatures again fall below 20°C (Gobler et al. 2005). If some wild clones of A. anophagefferens switch from being virally susceptible to virally resistant during the warming trend of late spring and switch from resistant to susceptible during the cooling trend of autumn, it would explain the initiation and persistence of brown tides during the summer months. The inability of AaV to lyse some clones of Aureococcus anophagefferens at higher temperatures may be associated with elevated bacterial densities at higher culture temperatures. A. anophagefferens Clone 1854 grown at 22°C in late exponential phase growth had twice the number of bacteria (1.7 ± 0.4 × 10^7 ml−1) of parallel cultures grown at 10°C (8.4 ± 0.2 × 10^7 ml−1). Adsorption of viruses onto bacterial cells or bacterial cells onto host surface viral receptor sites could prohibit viral infection of A. anophagefferens (Rabinovitch et al. 2003, Thyrhaug et al. 2003). Alternatively, AaV could be degraded and rendered inactive by the proteolytic action of bacteria at higher densities. As such, we speculate that the presence of significantly higher bacterial densities during the periods of warmer temperatures which exist during brown tides (Gobler & Sañudo-Wilhelmy 2003) may promote these mechanisms during bloom events. The results of some of our field experiments suggest that laboratory-propagated AaV can effectively reduce densities of bloom populations of Aureococcus anophagefferens (Figs. 5 & 6). In NY in 2002, the addition of 2 of the 5 viral strains to bloom water, contained in flasks and incubated in situ reduced densities of A. anophagefferens by >60% (Fig. 5) and in MD in 2003, the addition of a single viral strain had a similar impact (Fig. 6). Preliminarily, these results might suggest that AaV could serve as a moderately effective biocontrol of brown tides (Sengco & Anderson 2004). However, it is notable that although A. anophagefferens densities were significantly reduced during some of these 3 d experiments, >10^5 cells ml−1 remained unlysed by the end of the experiments (Figs. 5 & 6). This is more than 1 order of magnitude higher than densities found in lysable laboratory cultures 3 d after the addition of active AaV (Fig. 1). While some of these cells might have been lysed if the experiment had persisted longer, these remaining cells could represent a subpopulation of A. anophagefferens which is resistant to viral lysis (Table 2). If this were the case, this finding, taken with the resistance of many A. anophagefferens clones of AaV, suggests that viruses may have a greater impact on the clonal diversity of brown tide populations than on their abundances. Acknowledgements. We thank the following Southampton College students and faculty members for assistance with this project: Danielle Thibault, Jeffery Krause, Kristen Rathjen, Jessica Jaret, Gina, Franco, George Boneillo, Juleen Dickson, Glynis Pererya, David Barrieo, Matthew Vilbas, Sarah Deonarine, Florian Koch. This research was supported, in part, by EPA Star award #R82-9367-010. C.J.G.’s effort was also supported by by NOAA, Coastal Ocean Program ECO- HAB award #NA16OP2790. This is M SRC Contribution Number 1336, Lamont-Doherty Earth Observatory Contribution Number 7001, and ECOHAB contribution number 229. LITERATURE CITED Lomas NW, Glibert PM, Berg GM, Burford M (1996) Charac- terization of nitrogen uptake by natural populations of *Aureococcus anophagefferens* (Chrysophyceae) as a function of incubation duration, substrate concentration, light, and temperature. J Phycol 32:907–916 Submitted: September 15, 2006; Accepted: January 12, 2007 Proofs received from author(s): March 15, 2007 Editorial responsibility: Gunnar Bratbak, Bergen, Norway
Bacterial adrenergic sensors regulate virulence of enteric pathogens in the gut Cristiano G. Moreira, UT Southwestern Medical School Regan Russell, UT Southwestern Medical School Animesh Anand Mishra, UT Southwestern Medical School Sanjeev Narayanan, Kansas State University Jennifer M. Ritchie, University of Surrey Matthew K. Waldor, Howard Hughes Medical Institute Meredith M. Curtis, UT Southwestern Medical School Sebastian E. Winter, UT Southwestern Medical School David Weinshenker, Emory University Vanessa Sperandio, UT Southwestern Medical School Journal Title: mBio Volume: Volume 7, Number 3 Publisher: American Society for Microbiology: Open Access Journals | 2016-06-07, Pages e00826-16 Type of Work: Article | Final Publisher PDF Publisher DOI: 10.1128/mBio.00826-16 Permanent URL: https://pid.emory.edu/ark:/25593/rqvk4 Final published version: http://dx.doi.org/10.1128/mBio.00826-16 Copyright information: © 2016 Moreira et al. This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). Accessed August 11, 2019 9:49 PM EDT Bacterial Adrenergic Sensors Regulate Virulence of Enteric Pathogens in the Gut Cristiano G. Moreira,a,b,c Regan Russell,a,b Animesh Anand Mishra,a,b Sanjeev Narayanan,d Jennifer M. Ritchie,a Matthew K. Waldor,f Meredith M. Curtis,a,b Sebastian E. Winter,a David Weinschenker,a Vanessa Sperandio,a,b Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA; School of Pharmaceutical Sciences, State University of Sao Paulo (UNESP), Araraquara, Brazil; Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, USA; Department of Microbial Sciences, University of Surrey, Guildford, United Kingdom; Brigham and Women’s Hospital, Howard Hughes Medical Institute, Division of Infectious Diseases, Harvard Medical School, Boston, Massachusetts, USA; Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA C.G.M., R.R., and A.A.M. contributed equally to this work. ABSTRACT Enteric pathogens such as enterohemorrhagic Escherichia coli (EHEC) and Citrobacter rodentium, which is largely used as a surrogate EHEC model for murine infections, are exposed to several host neurotransmitters in the gut. An important chemical exchange within the gut involves the neurotransmitters epinephrine and/or norepinephrine, extensively reported to increase virulence gene expression in EHEC, acting through two bacterial adrenergic sensors: QseC and QseE. However, EHEC is unable to establish itself and cause its hallmark lesions, attaching and effacing (AE) lesions, on murine enterocytes. To address the role of these neurotransmitters during enteric infection, we employed C. rodentium. Both EHEC and C. rodentium harbor the locus of enterocyte effacement (LEE) that is necessary for AE lesion formation. Here we show that expression of the LEE, as well as that of other virulence genes in C. rodentium, is also activated by epinephrine and/or norepinephrine. Both QseC and QseE are required for LEE gene activation in C. rodentium, and the qseC and qseE mutants are attenuated for murine infection. C. rodentium has a decreased ability to colonize dopamine β-hydroxylase knockout (Dbh−/−) mice, which do not produce epinephrine and norepinephrine. Both adrenergic sensors are required for C. rodentium to sense these neurotransmitters and activate the LEE genes during infection. These data indicate that epinephrine and norepinephrine are sensed by bacterial adrenergic receptors during enteric infection to promote activation of their virulence repertoire. This is the first report of the role of these neurotransmitters during mammalian gastrointestinal (GI) infection by a noninvasive pathogen. IMPORTANCE The epinephrine and norepinephrine neurotransmitters play important roles in gut physiology and motility. Of note, epinephrine and norepinephrine play a central role in stress responses in mammals, and stress has profound effects on GI function. Bacterial enteric pathogens exploit these neurotransmitters as signals to coordinate the regulation of their virulence genes. The bacterial QseC and QseE adrenergic sensors are at the center of this regulatory cascade. C. rodentium is a noninvasive murine pathogen with a colonization mechanism similar to that of EHEC, enabling the investigation of host signals in mice. The presence of these neurotransmitters in the gut is necessary for C. rodentium to fully activate its virulence program, in a QseC/QseE-dependent manner, to successfully colonize its murine host. Our study data provide the first example of epinephrine and norepinephrine signaling within the gut to stimulate infection by a bacterial pathogen in a natural animal infection. The survival of an organism is dependent on its intrinsic ability to detect and efficiently respond to stress cues. The neurotransmitters epinephrine (Epi) and norepinephrine (NE) play a central role in stress responses in mammals. Notably, stress affects gastrointestinal (GI) function, leading to increased gastric acid production and intestinal motility, and can also alter the composition of the gut microbiota (1). Both epinephrine and norepinephrine have important biological roles in the human GI tract. Norepinephrine is synthesized locally within the enteric nervous system (ENS) by adrenergic neurons in the basal-lateral layer of the gut (2). Epinephrine is mostly synthesized in the adrenal medulla but can reach the gut through the bloodstream (3). These neurotransmitters play important GI functions, modulating intestinal smooth muscle contraction, submucosal blood flow, and chloride and potassium secretion (4). There is an important relationship between the gut microbiota and the availability of active epinephrine and/or norepinephrine in the lumen. These neurotransmitters are inactivated by the host by glucuronidation, and the GI microbiota encodes glucuronidases that deconjugate glucuronic acid from epinephrine and norepinephrine, increasing Received 6 May 2016 Accepted 10 May 2016 Published 7 June 2016 Editor Caroline S. Harwood, University of Washington Copyright © 2016 Moreira et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Address correspondence to Vanessa Sperandio, vanessa.sperandio@utsouthwestern.edu. This article is a direct contribution from a Fellow of the American Academy of Microbiology. External solicited reviewers: John Leong, Tufts University School of Medicine; Kendra Rumbaugh, Texas Tech University Health Sciences Center. the levels of these biologically active neurotransmitters in the lumen (5). Moreover, epinephrine and/or norepinephrine have direct effects on bacterial physiology and virulence gene expression through interaction with the bacterial adrenergic receptors QseC and QseE (see Fig. 3A) (6–24). The role of epinephrine and/or norepinephrine in stimulating virulence gene expression has been extensively studied in the human enteric pathogen enterohemorrhagic Escherichia coli (EHEC) (11, 19–21, 23, 25, 26). EHEC is a foodborne pathogen responsible for major outbreaks of bloody diarrhea and hemolytic uremic syndrome (HUS) worldwide (27). EHEC colonizes the colon, where it forms attaching and effacing (AE) lesions on enterocytes. The locus of enterocyte effacement (LEE) pathogenicity island contains most of the genes necessary for AE lesion formation. The LEE contains 41 genes, the majority of which are organized within five major operons: LEE1 to LEE5 (28–30). The LEE genes encode a type III secretion system (T3SS) (31), an adhesin (intimin) (32) and its receptor (Tir) (33), and transcriptional regulators, chaperones, and effector proteins (34–38). EHEC senses the host neurotransmitters epinephrine and/or norepinephrine through QseC and QseE, thereby relaying notification of the presence of these chemical signals to a complex regulatory cascade and leading to transcription of key virulence genes. QseC is at the top of this signaling cascade, and, upon sensing epinephrine, it activates expression of the qseEF genes. In addition to genetic regulation between these two systems, there is also cross talk at the phosphorylation level. QseC phosphorylates three response regulators (RRs), its cognate RR QseB, KdpE, and QseF. QseE, however, exclusively phosphorylates QseF. This signaling cascade operating via QseC directly activates transcription of the LEE through KdpE. LEE transcriptional expression is indirectly controlled through QseEF. QseEF repress expression of rcsB, which encodes an RR that also activates LEE transcription. Hence, the increased expression of rcsB in a qseE mutant leads to increased LEE expression (11, 19–21, 23–26). These transcription events ultimately enable the organism to form AE lesions and produce Shiga toxin (responsible for HUS), thereby leading to the clinical manifestations of infection (7, 19, 20, 23). However, studies of the role of these neurotransmitters in EHEC virulence during mammalian infection have been lacking because EHEC does not form AE lesions on the intestine of mice, and studies of the EHEC-host relationship at the level of intestinal disease have had to rely on expensive and genetically intractable animal models. A variety of other animal species, including mice, gnotobiotic piglets, baboons, ferrets, and calves, have been used as models to study the virulence of EHEC (39–48). EHEC is able to colonize streptomycin-treated mice; however, it does not cause AE lesions in these animals and its toxicity in this model is solely due to Shiga toxin (44, 45), given that these results could be reproduced using an E. coli K-12 strain carrying cloned stx genes (encoding Shiga toxin) (45). Ferrets (streptomycin treated) were also evaluated as a possible small-animal model for EHEC infection (46). These animals developed hematuria and/or histological damage of glomeruli or thrombocytopenia, but there was no evidence of colitis or AE lesion formation in intestinal epithelial cells. Thus, the ferret and the streptomycin-treated mouse models may serve as models for renal disease secondary to intestinal infection with EHEC. EHEC is able to cause AE lesions in large animals such as suckling neonatal piglets (42) and neonatal calves (39). However, these animals are expensive and difficult to manage for screening large numbers of potential virulence genes. Finally, the nonhuman primate animal models (baboons) are limited by the high cost. In the infant rabbit animal model, EHEC colonizes the large intestine, forming AE lesions and causing diarrhea (49, 50), but, unlike murine models, rabbits are genetically intractable, hampering studies assessing the host genetic contribution to EHEC intestinal infection. An alternative used by many investigators in the field is to study Citrobacter rodentium as a surrogate for EHEC. This natural murine pathogen, like EHEC, harbors the LEE (see Fig. 3B) and forms AE lesions on the intestine of mice, leading to colonic hyperplasia (51, 52). All of the known virulence genes of EHEC have been validated in vivo using C. rodentium murine infections (52–56). The utilization of the C. rodentium model capitalizes on merging the powerful genetically tractability of host and pathogen to unravel the mechanisms involved in host recognition and infection. Here we employed EHEC and C. rodentium animal models to investigate the role of epinephrine/norepinephrine and the bacterial adrenergic receptors QseC and QseE in the pathogenesis of noninvasive enteric pathogens. ## RESULTS ### The role of QseC and QseE in mammalian infections. The most suitable small-animal model for EHEC is the infant rabbit model, where EHEC colonizes the colon of these animals, forming AE lesions and causing disease. The proficiency of EHEC to colonize the intestine of these mice correlates with the severity of disease; hence, the assessment of CFUs of EHEC in the intestine of these animals provides a numeric readout of disease (49, 50). Using this infection model, we have previously shown that an EHEC qseC mutant is attenuated, with a decreased ability to colonize the colon, ileum, and cecum of these animals on day 5 (D5) postinfection (7). However, we did not know the contribution of the QseE adrenergic sensor for EHEC infection of infant rabbits. Moreover, we also have not investigated the pathogenicity of a double-sensor mutant. We have now assessed pathogenesis of EHEC qseE and qseEC mutants using this model. The qseE mutant initially (day 2 postinfection) colonizes the ileum and colon of these animals to higher levels than the wild type (WT) (Fig. 1) and later during infection (day 5) behaves similarly to the WT (Fig. 2). This initial higher colonization by the qseE mutant is congruent with the overexpression of the LEE genes (24). We have previously reported that, although qseC and qseE individual mutants can still sense epinephrine and norepinephrine to regulate certain arms of this signaling cascade, an EHEC qseEC mutant is unable to sense these neurotransmitters (24). The EHEC qseEC mutant presents decreased colonization of the ileum on day 2 postinfection (Fig. 1) and decreased colonization of the ileum, cecum, and colon and less bacteria within the stool at day 5 compared to the WT (Fig. 2), having a phenotype that mirrors that of the EHEC qseC mutant during infection of infant rabbits (7). This is not a surprising result, because QseC activates expression of the qseEF genes, being at the top of this signaling cascade (57). These data suggest that the ability to sense epinephrine and norepinephrine through both the QseC and QseE sensors promotes EHEC’s virulence during mammalian infection. **Epinephrine and norepinephrine regulate virulence gene expression in C. rodentium.** One limitation of the infant rabbit model is the inability to generate knockout animals to assess the role of the host genetic repertoire in pathogen-host associations. To address this limitation, we employed the C. rodentium murine... infection model. *C. rodentium* has the LEE genes (Fig. 3B) and colonizes and forms AE lesions in the colon (51, 52), which is the same GI site colonized by EHEC (58). Importantly, *C. rodentium* harbors the QseC and QseE adrenergic sensors. Both epinephrine and norepinephrine increased expression of virulence genes in *C. rodentium*, including the LEE genes (which encode a T3SS essential for intestinal colonization, colonic hyperplasia, and pathogenesis [52]), several effector genes (*nleA* and *nleB*), adhesin genes, and many genes within the QseC and QseE regulatory cascade (Fig. 3C; see also Fig. S2 in the supplemental material). QseC and QseE are involved in LEE and *nleA* gene regulation in EHEC, with QseC activating their expression, while QseE represses it (24). Similarly to EHEC, QseC also activates expression of the LEE and *nleA* genes in *C. rodentium* (see Fig. S1 and S2 in the supplemental material). However, QseE has a contrasting function in *C. rodentium*; while it represses expression of the LEE and *nleA* genes in EHEC, it activates expression of these genes in *C. rodentium* (see Fig. S1 and S2). It is worth noting that, while QseC and QseE are necessary for LEE gene activation in *C. rodentium* (see Fig. S1 and S2 in the supplemental material), and we have previously published results showing that *qseC*, *cra*, and *kdpE* mutants are attenuated for murine infection using high infectious doses of 10⁹ CFU (63, 64) and employing susceptible C3H-HeJ animals that succumb to death upon *C. rodentium* infection (65). Here we first refined these studies using different infectious doses to gain a full understanding of the attenuation of the *qseC* mutant. All experiments were performed with doses of 10⁵, 10⁸, and 10⁹ CFU using 10 mice per group (Fig. 4A to C). The WT-infected animals all succumbed to death eventually, with the lower infectious doses prolonging the time to death. The *qseC* mutant was attenuated compared to the WT results at all infectious doses, and at the lowest infectious dose (10⁵), all of the animals infected with the *qseC* mutant survived, while all animals... infected with the WT strain succumbed to death (Fig. 4C). We also tested the *C. rodentium* qseE mutant for murine infection using an infectious dose of 10⁹ CFU. Death of ΔqseE mutant-infected animals was delayed by 1 day compared to the WT results, a difference which is statistically significant (*P* < 0.02) (Fig. 4D). The colon weights of ΔqseE mutant-infected animals (a readout of colonic hyperplasia) were lower than the weights measured for animals infected with the WT strain, being similar to those seen with the control animals administered phosphate-buffered saline (PBS) (Fig. 4E). Of note, we have previously published that the colon weight of ΔqseC mutant-infected animals was also lower than that of WT-infected animals (63). Taken together, these data indicate that both the qseC and qseE *C. rodentium* mutants are attenuated for murine infection, in accordance with the role of these two sensors in activating expression of the virulence genes (see Fig. S1 and S2). Epinephrine and norepinephrine are required for full virulence of *C. rodentium* during mammalian infection. Norepinephrine is synthesized from dopamine by the enzyme dopamine β-hydroxylase (Dbh), and phenylethanolamine-N-methyl transferase (PNMT) synthesizes epinephrine from norepinephrine. To investigate the role of epinephrine and norepinephrine in *C. rodentium* infection, we devised experiments using Dbh knockout animals (*Dbh*⁻/⁻). These experiments were performed using Dbh⁺/⁻ mice (the heterozygous mice are known to behave as WT for production of epinephrine and norepinephrine and represent the parent strain for the knockout animals), and the Dbh⁻/⁻ mice (which do not produce any epinephrine or norepinephrine) (66). However, these mouse strains are derived from a mix of C57BL/6J and 129x1/SvEv mice, which are more resistant to *C. rodentium* infection than C3H-HeJ mice. 129x1/SvJ mice are colonized at high numbers by *C. rodentium* and develop colonic hyperplasia and inflammation and compromised crypt integrity and also lose goblet cells, similarly to the results of *C. rodentium* infection of C3H-HeJ. However, unlike C3H-HeJ mice, 129x1/SvJ mice resolve and survive infection (65). Our pilot studies with 129x1/SvJ animals also confirmed that they develop disease and are colonized by *C. rodentium* but do not die (see Fig. S3 in the supplemental material). Hence, we decided not to perform survival studies in the Dbh⁺/⁻ and Dbh⁻/⁻ animals and to focus on other parameters of *C. rodentium*-mediated disease. In these resistant *C. rodentium* murine infection models, colonization of the intestine (CFU counts) correlates with the severity of the disease (65). These animals were infected with 1 × 10⁹ CFU of the *C. rodentium* WT strain and of the qseC, qseE, and qseEC mutants. We monitored CFU, LEE gene expression, and the composition of the microbiota in their stools during infection (Fig. 5, 6, and 7). We also performed comprehensive pathology analyses of their colons (Ta- --- **FIG 2** EHEC infection in infant rabbits at day 5 postinfection. Data depict CFUs of EHEC in the ileum (A), cecum (B), colon (C), and stool (D). ***, P < 0.01; ***, P < 0.001. The animals were sacrificed on day 7, which, in this strain of mice, in our hands, corresponds to the peak of disease. There are no previous reports on whether the presence or absence of epinephrine and norepinephrine affects the composition of the gut microbiota. Because the virulence and infectivity of EHEC and C. rodentium are altered by the microbiota (64, 67–69) and because the microbiota plays an important role in the availability of active epinephrine and/or norepinephrine in the lumen (5), we investigated the compositions of the microbiotas of uninfected and infected Dbh+/H11001/H11002 and Dbh+/H11002/H11002 animals at the phylum level. The compositions were similar on day 1 of C. rodentium infection (Fig. 5A). At day 7, the uninfected animals had microbiotas that were similar to those of each other and to their microbiotas prior to infection (Fig. 5B). Infection of Dbh+/− and Dbh−/− mice resulted in changes in the microbiota with all strains. However, these changes differed depending on whether these animals were or were not able to produce epinephrine and norepinephrine. At day 7, in animals infected with WT C. rodentium, the microbiota composition was dominated by γ-proteobacteria in both strains of mice, but the Dbh−/− animals had more Firmicutes than the Dbh+/− animals, and the Dbh+/− animals had more Bacteroidetes. At day 7 postinfection, the ΔqseC mutant-infected animals also had their microbiota dominated by γ-proteobacteria in both strains of mice but to a lesser degree than the animals infected with the WT strain. The animals infected with the ΔqseC mutant showed an enhancement of Bacteroidetes and Firmicutes populations compared to WT-infected animals but kept the same pattern of the Dbh+/− mice being enriched for Bacteroidetes, while the Dbh−/− mice were enriched for Firmicutes. At day 7 postinfection, the ΔqseE mutant-infected animals had similar microbiota profiles in the Dbh+/− and Dbh−/− strains of mice. However, compared to WT-infected animals, ΔqseE mutant-infected animals had even more γ-proteobacteria and fewer Bacteroidetes and no Firmicutes. The most striking microbiota differences between Dbh+/− and Dbh−/− mice occurred at day 7 in animals infected with the double qseEC mutant. The microbiota of the ΔqseEC mutant-infected Dbh+/− mice was dominated by Firmicutes, in contrast to animals infected with the WT strain, and presented the least prevalence of γ-proteobacteria. The microbiota of the ΔqseEC mutant-infected Dbh−/− mice was very similar to the microbiota of the mice infected with the WT strain, with a prevalence of γ-proteobacteria and few Bacteroidetes and more Firmicutes in relation to Bacteroidetes (Fig. 5B). These studies suggest that the GI microbiotas are similar in the absence and presence of epinephrine and norepinephrine hormones in the gut to activate the LEE function in vivo. Moreover, whether C. rodentium can sense these hormones also differentially impacts the composition of the microbiota in Dbh+/− and Dbh−/− animals. The observation that the microbiotas of Dbh+/− and Dbh−/− mice infected with the ΔqseEC mutant also differ suggests that there may be still another epinephrine/norepinephrine sensory mechanism in EHEC in addition to QseC and QseE. A third epinephrine/norepinephrine sensory mechanism has been suggested to exist in Salmonella enterica (70). The levels of colonization differed dramatically when WT C. rodentium was used to infect Dbh+/− versus Dbh−/− mice. Throughout the infection, WT C. rodentium colonized Dbh+/− animals to higher levels than the Dbh−/− mice (differences of between 2 and 3 logs), suggesting that epinephrine and norepinephrine profoundly alter infection in vivo (Fig. 6). Colonization of the qseC, qseE, and qseEC mutants in the Dbh+/− mice was decreased compared to the WT strain (Fig. 6), indicating that QseC and QseE promote colonization during infection. The difference in colonization of Dbh+/− versus Dbh−/− mice by any given strain was largely lost in the infections by the qseC, qseE, and qseEC mutants (Fig. 6), suggesting that differences in colonization upon infection of Dbh+/− versus Dbh−/− mice depend on both QseC and QseE, and indicating that both of these sensors are required to distinguish an intestine with epinephrine and norepinephrine from one without and to better colonize the former. Expression of the LEE genes in WT C. rodentium was decreased in the Dbh−/− animals compared to the Dbh+/− animals, indicating that C. rodentium senses epinephrine and norepinephrine in vivo (Fig. 7). These data suggest that the absence of the host epinephrine and norepinephrine hormones in the Dbh−/− mice prevents C. rodentium from optimally activating LEE gene expression, leading to decreased gut colonization (Fig. 6). Moreover, LEE expression is decreased in the qseC, qseE, and qseEC mutants compared to the WT strain during infection of both Dbh+/− and Dbh−/− mice, which suggests that the QseC and QseE sensors function in vivo. Expression of the LEE espA and tir genes was further decreased in the Dbh−/− mice infected with the qseC mutant compared to infection of the Dbh+/− mice and was decreased to similar levels in the two murine strains infected with the qseE mutant. Expression of tir was decreased in the qseEC mutant compared to the WT in both murine strains, but expression of espA, albeit reduced compared to the level seen with the WT in all animals infected with the qseEC mutant, was increased in the Dbh−/− mice compared to the Dbh+/− animals (Fig. 7), which suggests that there is yet another manner to distinguish these animals in addition to analysis of QseC and QseE. Taken together, these data suggest that QseC and QseE are involved in C. rodentium sensing of epinephrine and norepinephrine in the gut to activate the LEE and colonize the GI tract. Concerning intestinal pathology, uninfected Dbh−/− ani- mals presented more lymphocytes than \( Dbh^{+/−} \) animals, suggesting that epinephrine and norepinephrine play a role in preventing inflammation in the gut. Infection with WT \( C. rodentium \) led to increased edema, decreased crypt integrity, and increased inflammation in the \( Dbh^{−/−} \) animals compared to the \( Dbh^{+/−} \) animals. Although expression of the LEE and \( C. rodentium \) colonization were decreased during infection of the \( Dbh^{−/−} \) animals, the inherent increased inflammation in the intestine of these mice probably led to this increase in pathology, even though there was a smaller amount of pathogen, with decreased virulence. Infection with both the \( qseC \) and \( qseE \) mutants also led to increased pathology in the \( Dbh^{−/−} \) animals. However, infections with both mutants led to less pathology and inflammation than was seen with the WT in both the \( Dbh^{−/−} \) and \( Dbh^{+/−} \) mice (Table 1). These data suggest that although the activity of the \( qseC \) and \( qseE \) mutants was attenuated compared to that of the WT, the \( Dbh^{−/−} \) mice still presented more inflammation and decreased crypt integrity, even when infected with attenuated strains of \( C. rodentium \), because of their inherent gut inflammation (66). The \( qseEC \) mutant, however, showed decreased pathology in comparison to the WT in both mouse strains and was similarly attenuated in the ΔqseC ΔDbh−/− and ΔqseE ΔDbh−/− mice. In fact, the pathology scores determined for the two mouse strains infected with the double mutant were largely similar to the scores determined for the uninfected (PBS-treated) animals. The qseEC mutant has both epinephrine/norepinephrine sensors deleted, suggesting that a C. rodentium strain that cannot sense these hormones is attenuated for disease and cannot even cause issues in the Dbh−/− mice, even though they have inherent gut inflammation. It is worth considering that the QseC and QseE sensors also sense other signals in addition to epinephrine and norepinephrine. QseC senses microbiota-produced signal autoinducer-3 (AI-3) (19, 20), and QseE senses SO₄ and PO₄ (23). Hence, in addition to the absence of the adrenergic signals, the qseEC mutant is also impaired for sensing other signals that contribute to virulence gene regulation in EHEC and C. rodentium. **DISCUSSION** Epinephrine and norepinephrine exert a profound effect in the host physiology and immune system, and the ability of bacteria to sense these hormones may facilitate gauging the fitness of the host (19, 20, 71). Specifically, in the GI tract, which is one of the most prominent sites in the human body where host/microbe associations are paramount, these neurotransmitters play important functions in gut homeostasis and physiology (19, 20, 71). This two-way-street communication is currently gaining appreciation given that there are important relationships between neurotransmitters and the GI microbiota, with the microbiota inducing biosynthesis of the serotonin neurotransmitter (72) and modulating the levels of active epinephrine and norepinephrine in the gut lumen (5). Disruption of these relationships and of the structure of the bacterial communities that inhabit the gut can contribute to dysbiosis leading to disease. An important insight that causes dysbiosis is infection by an invading pathogen. It is known that invading enteric pathogens such as Salmonella enterica and C. rodentium cause inflammation within the gut that in turn diminishes the overall numbers of bacteria in the microbiota, sometimes acting as a competitive advantage to the pathogen (73, 74). Additionally, infection with C. rodentium also causes significant changes in the structure of the microbial community, decreasing the number of anaerobes and increasing the numbers of γ-proteobacteria (73). C. rodentium is a murine pathogen that models enteric infection by the human pathogen EHEC, and both pathogens sense epinephrine and norepinephrine to activate their virulence genes (11, 19–21, 23, 25, 26) (Fig. 3; see also Fig. S1 and S2 in the supplemental material). These two neurotransmitters are sensed by the bacterial QseC and QseE sensors (20, 23). In both EHEC and C. rodentium, the qseC and qseEC mutants are attenuated for animal infections (7, 20, 63) (Fig. 2 to 4 and 6). The qseEC mutant is largely unable to detect and respond to epinephrine and/or norepinephrine (24) highlighting the important role of these neurotransmitters in enteric infection. However, the phenotypes of the qseE mutants differ between these pathogens (24) (Fig. 1 to 4 and 6; see also Fig. S1 and S2 in the supplemental material). An explanation for this difference is that QseE acts indirectly and posttranscriptionally in expression of the LEE island as well as of other effectors, such as NleA (24, 61). QseE exclusively phosphorylates its cognate response regulator (RR), QseF (75), while QseC acts through three RR s, its cognate QseB and the noncognates KdpE and QseF (21). The QseC tripartite signaling cascade activates LEE expression directly through KdpE and the glucanogenesis sensor Cra (24). QseE acts indirectly through QseF, which directly activates expression of the glmY gene, and the GlmY sRNA mediates degradation of the LEE4 and LEE5 transcripts in EHEC (61). The homology between the LEE1, LEE2, and LEE3 operons of EHEC and C. rodentium is high; however, the sequences of LEE4 and LEE5 are very divergent (Fig. 3B), and there is consequently a high probability that they would be differentially regulated at the posttranscriptional level. In fact, posttranscriptional regulation has been reported to differ even within EHEC strains (76–78). These data indicate that, although C. rodentium can be useful for addressing **TABLE 1 Pathology scoring of large intestine** <table> <thead> <tr> <th>Sample</th> <th>Edema</th> <th>Crypt integrity</th> <th>Lymphocyte</th> <th>Neutrophil</th> <th>Apoptosis</th> <th>Vasculitis</th> </tr> </thead> <tbody> <tr> <td>PBS Dbh+/−</td> <td>0</td> <td>0</td> <td>0</td> <td>0</td> <td>0</td> <td>0</td> </tr> <tr> <td>WT Dbh+/−</td> <td>2</td> <td>2</td> <td>3</td> <td>1</td> <td>4–8</td> <td>3</td> </tr> <tr> <td>ΔqseC Dbh+/−</td> <td>0</td> <td>0</td> <td>1</td> <td>0</td> <td>0</td> <td>0</td> </tr> <tr> <td>ΔqseE Dbh+/−</td> <td>0</td> <td>0</td> <td>4</td> <td>0</td> <td>1–2</td> <td>1</td> </tr> <tr> <td>ΔqseEC Dbh+/−</td> <td>1</td> <td>0</td> <td>4–6</td> <td>1</td> <td>1–2</td> <td>1</td> </tr> <tr> <td>PBS Dbh−/−</td> <td>0</td> <td>0</td> <td>4</td> <td>0</td> <td>0</td> <td>0</td> </tr> <tr> <td>WT Dbh−/−</td> <td>3</td> <td>4</td> <td>6–10</td> <td>4</td> <td>6–8</td> <td>1</td> </tr> <tr> <td>ΔqseC Dbh−/−</td> <td>1.5</td> <td>2</td> <td>5–6</td> <td>6</td> <td>5</td> <td>1</td> </tr> <tr> <td>ΔqseE Dbh−/−</td> <td>0</td> <td>2</td> <td>5–6</td> <td>4</td> <td>2</td> <td>0</td> </tr> <tr> <td>ΔqseEC Dbh−/−</td> <td>0</td> <td>0</td> <td>3</td> <td>0</td> <td>0</td> <td>0</td> </tr> </tbody> </table> *Scores for vasculitis are 0 for no evidence of vasculitis and 5 for the most severe vasculitis (i.e., loss of vessel wall architecture due to infiltration of leukocytes, presence of nuclear debris, and exudation of eosinophilic proteinaceous material; this is called leukocytoclastic vasculitis/fibrinoid necrosis in pathology literature). All of these changes are statistically significant (P < 0.05).* *Scores for neutrophilic infiltration in the wall (mainly perivascular in the submucosa but also seen occasionally in the lamina propria and the lumen) are 0 for no infiltration and 6 for the highest infiltration.* *Scores for apoptosis represent the number of apoptotic cells per ×600 field (five fields were counted). Numbers of apoptotic cells occasionally differed in areas of greater severity versus lesser severity; those instances are represented by two numbers.* *Scores for crypt integrity are 0 for normal crypts, 1 for irregular crypts, 2 for mild crypt loss, 3 for severe crypt loss, and 4 for complete crypt loss.* *Scores for (submucosal) edema are 0 for no edema and 5 for the highest edema in the submucosa.* and mirroring certain aspects of EHEC pathogenesis, allowing for murine infections, one has to be cautious and aware of some of the limitations of this model. However, even with some of these limitations, the double qseEC mutant of both pathogens is attenuated for mammalian infection (Fig. 1 to 4 and 6). The ability to harness the genetic tractability of murine models allowed us to investigate for the first time the role of epinephrine and/or norepinephrine impacting the pathogenesis of a noninvasive enteric pathogen, *C. rodentium*, as well as EHEC, does not breach the intestinal mucosa and invade the host systemically; the bacteria are restricted to the mucosal layer of the intestine (58, 79). It is very well established that norepinephrine is present in the basolateral layer of the intestine, where it is produced by adrenergic neurons of the enteric nervous system (2). However, whether it is present in the mucosal and luminal surface of the intestine, which is the compartment occupied by both EHEC and *C. rodentium*, was unresolved for many years. Recent evidence indicates that active norepinephrine is present in the lumen and mucosal layer and that the microbiota plays a key role in facilitating activation of this neurotransmitter (5). Using *Dbh<sup>−/−</sup>* knockout mice that do not produce epinephrine and norepinephrine, we have now been able to show that optimal LEE expression is dependent on these neurotransmitters and is also dependent on QseC and QseE (Fig. 7), leading to decreased levels of gut colonization by *C. rodentium* in these knockout animals (Fig. 6). There is a growing appreciation of the complex microbial in- **FIG 6** CFUs in stools of *Dbh<sup>+/−</sup>* and *Dbh<sup>−/−</sup>* mice infected with WT, ΔqseC, ΔqseE, and ΔqseEC *C. rodentium* on days 1 to 7. PBS mice were used as negative controls. *, *P* < 0.0001. teractions within the gut-brain axis. Recent research has been elucidating how microbes can affect host behavior, and there is also a strong link between neurological function and the gut microbiota. Neurological diseases, such as autism, depression, and neurodegenerative diseases, are often strongly influenced by intestinal factors (80). The host neurotransmitters can also influence microbial behaviors, with studies of epinephrine and norepinephrine being at the forefront of this research (71). Although most of the epinephrine/norepinephrine modification of bacterial behavior was performed using gut pathogens, we could investigate these relationships in vivo only now using genetically tractable microbial and host systems. MATERIALS AND METHODS Isogenic mutant construction. Nonpolar mutants of qseE and qseEC in C. rodentium were constructed through the use of a lambda Red system (81). Briefly, PCR products were amplified from plasmid pKD3 with flanking regions matching qseE and were transformed into the C. rodentium WT or the qseC mutant (63) expressing the RED genes from plasmid pCP20, which were transformed into the WT or the tium expression efficiency and template specificity. Quantitative real-time PCR (qRT-PCR) was performed as previously described (21) in a one-step reaction using a RiboPure bacterial RNA isolation kit (Ambion) following the manufacturer’s guidelines. The primers used in the real-time assays were designed using Primer Express v1.5 (Applied Biosystems) (63) and were validated for amplification efficiency and template specificity. Quantitative real-time PCR (qRT-PCR) was performed as previously described (21) in a one-step reaction using an ABI 7500 sequence detection system (Applied Biosystems). Data were collected using ABI Sequence detection 1.2 software (Applied Biosystems). All data were normalized to an rpoA (RNA polymerase subunit A) endogenous control and analyzed using the comparative cycle threshold (Ct) method. Virulence gene expression was presented as fold changes over the WT expression level. Error bars indicate the standard deviations of the fold change values. The Student unpaired t test was used to determine statistical significance. Western blots of secreted proteins. For Western blot analyses of secreted proteins, all cultures were grown in DMEM to an OD600 of 0.4 in the presence or absence of 30 μM epinephrine at 37°C, and proteins were isolated as previously described (31). Bovine serum albumin (BSA) (10 μg) was added to secreted proteins prior to concentration and loading such that the efficiencies of processing were known to be equivalent from sample to sample. Membranes were probed using an anti-EspB antiserum. WT mouse infection experiments. For mouse survival experiments, 10 3.5-week-old female C3H/HeJ or 129x1/SvJ mice per group were infected by oral gavage with multiple infectious doses of wild-type and ΔqseE and ΔqseC C. rodentium strains by oral gavage with 100 μl of PBS. Mouse survival in each group (10 animals per group) was accessed over the course of 14 to 26 days. The Kaplan-Meier test was used to determine statistical significance. For colon weight measurement, five 3.5-week-old female C3H/HeJ or 129x1/SvJ mice per group were infected with 1 × 10^9 cells of wild-type and ΔqseE and ΔqseC C. rodentium strains. The infected mice were sacrificed on day 6 postinfection, and their colons were taken, washed, and weighed. Dbh^−/− knockout mouse assays. Dopamine β-hydroxylase knockout (Dbh^−/−) mice, maintained with a mixed C57BL/6j and 129 SvEv background, were generated at Emory University as previously described (82) and were shipped to the University of Texas (UT) Southwestern Medical School. Next, these 129x1/SvJ mice were housed in a specific-pathogen-free facility at the UT Southwestern Medical Center. All experiments were performed under IACUC-approved protocols. At 6 to 11 weeks of age, the mice were orally infected by gavage (either mock infected with PBS or orally infected with 1.3 × 10^9 CFU of the C. rodentium WT strain [ICC168] or of ΔqseC, ΔqseE, or ΔqseCE isogenic mutants). Mice were monitored daily for survival. The experiments were performed at least twice with a total of 6 mice per group. Colonization changes and virulence gene expression levels were measured directly from RNA extracted from FIG 7 Expression of the LEE espA and tir genes, measured by qRT-PCR, in stools of Dbh^+/− and Dbh^−/− mice infected with WT, ΔqseC, ΔqseE, and ΔqseEC C. rodentium on day 7 postinfection. PBS mice were used as negative controls. *, P < 0.05; **, P < 0.0001. fetal pellets collected in triplicate daily up to day 7 postinfection. The mice were also monitored for weight changes and colon macroscopic differences after euthanization. CFU change curves reflect the averages and standard deviations (SD) of the experiment results. Littermate The severity of intestinal pathology was analyzed based on the following scoring system: for edema, 0 (no edema) to 5 (highest edema in the wall); for crypt integrity, 1, normal, 2, irregular crypts, 3, mild changes were analyzed in a double-blind fashion at Kansas State University. ACKNOWLEDGMENTS This work was supported by the National Institutes of Health (NIH) grants AI101472, AI053067. M.M.C. was supported through NIH Training Grant 5 T32 AI7520-14. The contents are solely our responsibility and do not represent the official views of the NIH NIAID. FUNDING INFORMATION This work was funded by the National Institutes of Health (NIH) grants AI101472, AI053067, and AI053067. REFERENCES 29. Walters M, Sperandio V. 2006. Autoinducer 3 and epinephrine signaling 44. Wadlowski EA, Burris JA, O’Brien AD. 1990. Mouse model for colo- denization and disease caused by enterohemorrhagic Escherichia coli O157: Acute renal tubular necrosis and death of mice orally infected with Esch- erichia coli strains that produce Shiga-like toxin type II. Infect Immun 58:3959–3965. biosynthesis in a baboon model of Shiga toxin mediated hemolytic uraemic syndrome. Nephron 92:363–368. 61. Hansen AM, Kaper JB. 2009. Hfq affects the expression of the LEE patho-
ABSTRACT Wavenumber-1 wind speed asymmetries in 35 hurricanes are quantified in terms of their amplitude and phase, based on aircraft observations from 128 individual flights between 1998 and 2011. The impacts of motion and 850–200-mb environmental vertical shear are examined separately to estimate the resulting asymmetric structures at the sea surface and standard 700-mb reconnaissance flight level. The surface asymmetry amplitude is on average around 50% smaller than found at flight level, and while the asymmetry amplitude grows in proportion to storm translation speed at the flight level, no significant growth at the surface is observed, contrary to conventional assumption. However, a significant upwind storm-motion-relative phase rotation is found at the surface as translation speed increases, while the flight-level phase remains fairly constant. After removing the estimated impact of storm motion on the asymmetry, a significant residual shear direction-relative asymmetry is found, particularly at the surface, and, on average, is located downshear to the left of shear. Furthermore, the shear-relative phase has a significant downwind rotation as shear magnitude increases, such that the maximum rotates from the downshear to left-of-shear azimuthal location. By stratifying observations according to shear-relative motion, this general pattern of a left-of-shear residual wind speed maximum is found regardless of the orientation between the storm’s heading and shear direction. These results are quite consistent with recent observational studies relating western Pacific typhoon wind asymmetries to environmental shear. Finally, changes in wind asymmetry over a 5-day period during Hurricane Earl (2010) are analyzed to understand the combined impacts of motion and the evolving shear. 1. Introduction Surface winds in tropical cyclones (TCs) are an important quantity to measure, particularly since the maximum wind speed in a TC defines the storm’s intensity. Perhaps more important for practical purposes, however, is observing the full TC wind field, for example as quantified by integrated kinetic energy (Powell and Reinhold 2007). Storm surge flooding generated by landfalling TCs, which is also related to the size of the wind field (Irish et al. 2008), is responsible for far greater property damage and more deaths than result directly from wind. Storm surge forecasts therefore rely heavily on accurate forecasts of the surface wind field, including both the maximum wind speed (Xie et al. 2006) and asymmetries (Houston et al. 1999). Observing the strong TC surface winds over the ocean has historically been limited, due to a relative paucity of observational platforms, instrumentation failures, and the inherent danger of low-level manned aircraft flight in extreme conditions. Indirect methods have been developed to infer surface winds from observations well above the TC boundary layer (Franklin et al. 2003; Powell et al. 2009), from the TC minimum central pressure (Knaff and Zehr 2007), and from satellite imagery (Velden et al. Direct surface wind data from global positioning system (GPS) dropwindsondes have greatly enhanced our understanding of boundary layer wind structures (Franklin et al. 2003; Powell et al. 2003; Kepert, 2006a,b; Schwendike and Kepert 2008), but spatial resolution limitations from the individual point measurements often prevent a detailed description of the full wind field in most cases (Landsea et al. 2004). Recently, observations of the TC surface wind field have become available from stepped-frequency microwave radiometers (SFMRs; Uhlhorn et al. 2007), now installed on all operational and research hurricane reconnaissance aircraft flying in the Atlantic basin. The advantage of SFMR wind data is high spatial resolution radially with respect to the storm center, and relatively broad spatial coverage over the entire cyclone, since aircraft can traverse four quadrants of a storm in a matter of hours. Despite the improved surface wind sampling by SFMR, observing the peak 1-min surface wind in a TC remains elusive, since the maximum wind may be associated with transient eyewall vorticity maxima (EVM; Marks et al. 2008; Nolan et al. 2009) embedded within the spatially extensive eyewall region. A recent study has shown the highest observed SFMR wind over a single aircraft mission wind tends to underestimate the maximum 1-min wind speed by 6%-9% (Uhlhorn and Nolan 2012). However, the maximum wind speed is dominated by a relatively steady, and readily observable, symmetric wavenumber-0 (WN0) mean plus a wavenumber-1 (WN1) asymmetry (Vukicevic et al. 2014). Numerous theoretical (e.g., Reasor et al. 2004; Riemer et al. 2010), observational (e.g., Reasor et al. 2000; Black et al. 2002; Corbosiero and Molinari 2002, 2003; Knaff et al. 2004; Cecil 2007; Reasor et al. 2013), and numerical (e.g., Wang and Holland 1996; Bender 1997; Frank and Ritchie 2001; Rogers et al. 2003; Wu et al. 2006; Braun and Wu 2007; Davis et al. 2008) studies of TCs in vertically sheared environments have described a typical asymmetric eyewall structure, in which the vortex tends to tilt roughly downshear, eyewall convection initiates in the downshear-right quadrant collocated with maximum boundary layer inflow, and precipitation is maximized downshear left. At extended radii, Hence and Houze (2008) described a process whereby rainbands outside of the radius of maximum winds (RMW) may be responsible for local horizontal wind maxima well above the boundary layer, and these maxima may project onto the low-wavenumber asymmetric structure, including horizontal winds. Following this description, Didlake and Houze (2009) presented evidence that downdrafts associated with tilted convective cores could transport momentum to the surface, possibly impacting the low-wavenumber near-surface horizontal wind field. Boundary layer wind asymmetries have also been attributed to storm translation (e.g., Shapiro 1983), in which differential friction across the storm yields convergence and forced vertical ascent; however, Corbosiero and Molinari (2003) cast some doubt on this result due to a preferential orientation of motion and shear directions. Within the context of sheared TCs, it should be noted that observational studies of horizontal wind asymmetric structure, especially near the surface, have been conducted far less frequently than have studies of convection and vertical motion asymmetries. With recent improvements to observing system capabilities, more accurate parametric representations of TC surface winds may now be possible. Traditionally, earth-relative surface wind fields have been approximated as a simple translating axisymmetric vortex (e.g., Holland 1980), with a WN1 asymmetric component owing to the translational velocity (Georgiou 1985). This general practice of assuming that the asymmetry is maximized to the right of the storm track continues to this day, albeit with minor modifications (e.g., Xie et al. 2006; Hu et al. 2012), since consistent field observations have not routinely been available to quantify the amplitude and phase over a broad range of TC structures. Studies have suggested that there are several other interrelated processes that might be responsible for asymmetric boundary layer wind structure, including variations in surface friction (Shapiro 1983; Kepert 2001), the β effect (Ross and Kurihara 1992; Bender 1997), potential vorticity anomalies associated with asymmetric diabatic heating (Wang and Holland 1996), and environmental vertical shear (Rogers and Uhlhorn 2008). More recently, near-surface typhoon wind asymmetries have been examined using mesoscale analysis fields (Ueno and Kunii 2009) and National Aeronautics and Space Administration (NASA) Quick Scatterometer (QuikSCAT) data (Ueno and Bessho 2011). Both of these studies emphasized a preferential left-of-shear storm-relative surface tangential wind asymmetry that was amplified when the vertical shear was stronger. Surface wind analysis algorithms have been developed to provide guidance for forecasters, such as axisymmetric parametric models, variants based on these simple models, and near-real-time two-dimensional field analyses based on observations in the TC environment. Parametric models typically represent the wind field based on a few input parameters, while more sophisticated analyses range from objective statistical representations such as are utilized in H*Wind (Powell and Houston 1996; Powell et al. 2010) and variational fitting approaches (Knaff et al. 2011; Bell et al. 2012), as well as... data assimilative models with dynamical constraints (e.g., Aksoy et al. 2013). To address the issue of the maximum resolvability of the surface wind field from standard aircraft observations, a semispectral analysis algorithm is developed to quantify the TC surface wind structure for a sample of Atlantic basin hurricanes (35) obtained on 128 aircraft missions over the past several years (1998–2011). In addition, such an analysis is easily applied to high-resolution numerical forecast model wind fields for scale-consistent comparison with observations (Vukicevic et al. 2014). The purpose of this study is to document low-wavenumber surface wind asymmetries in hurricanes, and their relationships to motion and environmental shear, focusing particular attention on asymmetries at the radius of maximum wind. Relationships between surface and flight-level (typically, 700 mb) asymmetries are also developed. In section 2, the data sample and processing techniques are discussed, and the analysis methodology is developed. Section 3 presents the analysis results, composited separately relative to motion and shear (both magnitude and direction), and the evolution of asymmetries in an individual case study of Hurricane Earl (2010) is examined in section 4. In section 5, implications for the results on the coupling of kinematic and convective asymmetries are discussed, and finally section 6 summarizes the results and suggests directions for future study. 2. Data and methodology a. Sample hurricanes SFMR surface and flight-level wind speed data obtained from 128 aircraft missions in 35 hurricanes between 1998 and 2011 are utilized to construct wind field analyses. Figure 1 shows geographic locations of storms at the time of analysis. Storms range from categories 1 through 5 on the Saffir–Simpson hurricane scale, and cover a broad range of storm motion speeds and shear magnitudes (Fig. 2). Storm intensity in terms of maximum wind speed \( V_{\text{max}} \) and storm motion speed \( V_{\text{storm}} \) are obtained from the Hurricane Database version-2 (HURDAT2) derived from the National Hurricane Center’s (NHC) best track dataset (Jarvinen et al. 1984) corresponding to the time of aircraft observation. The 850–200-mb environmental vertical shear \( V_{\text{shr}} \) obtained from the Statistical Hurricane Intensity Prediction Scheme (SHIPS; DeMaria et al. 2005) re-analysis database (containing years 1982–2012) is the mean value over the 0–500-km radius centered on the storm after removing the vortex. Table 1 lists hurricanes and corresponding numbers of aircraft missions. Where distinctions are necessary, cardinal directions are identified either in an earth-relative coordinate as north (N), east (E), south (S), and (W); in a storm-heading-relative coordinate as forward of motion (FM), right of motion (RM), behind motion (BM), and left of motion (LM); or in a shear-heading-relative coordinate as downshear (DS), right of shear (RS), upshear (US), and left of shear (LS). In all cases, an angle of 0° is directed either N, FM, or DS, and angles are measured positive clockwise. For motion and shear-relative angles, the cyclic ambiguity point is set at \( \pm 180° \) throughout. Since asymmetric wind structure theoretically results from storm motion (Shapiro 1983; Kepert 2001), and possibly environmental shear (Rogers and Uhlhorn 2008; Ueno and Kunii 2009), the relationship between motion and shear is considered. Corbosiero and Molinari (2003) analyzed this relationship to understand the relative importance of motion and shear on convective asymmetries based on lightning flash spatial distribution. Here, this shear-relative motion analysis methodology is followed, with some minor convention changes for convenience. Frequency distributions of motion and shear directions (headings), and the difference between the two, are shown in Fig. 3 for the analyzed sample. The sample vector-mean hurricane travels at \( V_{\text{storm}} = 5.1 \text{ m s}^{-1} \), heading \( \theta_{\text{storm}} = 320° \) (toward NW; Fig. 2a). The environmental shear is more broadly distributed with a vector mean of \( V_{\text{shr}} = 6.5 \text{ m s}^{-1} \), heading \( \theta_{\text{shr}} = 51° \) (from SW; Fig. 2b). Subtracting the shear direction from the motion direction (Fig. 2c) results in a typical storm motion that is downshear left \( \text{mean} (\theta_{\text{storm}} - \theta_{\text{shr}}) = -36° \). Note that the scalar mean directional difference does not generally equate to the difference between vector means. Corbosiero and Molinari (2003) also reported a typical downshear-left motion direction for their sample, most often between \(-45° \) and \(-30° \) relative to the shear direction. For reference, over the entire 1982–2012 Fig. 1. Geographical locations of hurricanes analyzed for this study. SHIPS database, the mean hurricane travels at $V_{\text{storm}} = 6.1 \text{ m s}^{-1}$ with heading $\theta_{\text{storm}} = 347^\circ$, and experiences shear of $V_{\text{shr}} = 8.1 \text{ m s}^{-1}$ heading $\theta_{\text{shr}} = 67^\circ$, suggesting the sample analyzed here is a reasonable representation of North Atlantic hurricanes in general. b. SFMR surface wind processing The SFMR measures brightness temperatures at six frequencies in the microwave C band, from which the surface wind speed is retrieved. A geophysical model (Uhlhorn and Black 2003; Uhlhorn et al. 2007), which relates surface emission to wind speed, has been developed with the aid of in situ observations by GPS dropwindsondes. Wind observations are computed every 30 s, and each value corresponds to the highest 10-s-average wind over consecutive 30-s intervals, as is produced for real-time operations. This peak 10-s value along the flight track represents a 1-min-average value at a fixed point (Powell et al. 1991; Uhlhorn and Nolan 2012). Recent studies have examined SFMR winds to reveal some minor deficiencies under specific situations. Powell et al. (2009) analyzed differences in SFMR wind speeds relative to dropwindsondes as a function of storm-motion-relative azimuthal angle, and found a small residual asymmetry of amplitude $\sim 2 \text{ m s}^{-1}$. A similar result was found for a smaller sample by Uhlhorn and Black (2003). It was hypothesized that this bias was due to sea state asymmetry related to variable wind–wave interactions around a storm. This bias correction [Eq. (1) in Powell et al. (2009)] is applied to the winds in this study. The SFMR is designed to measure surface winds in all-weather conditions, including heavy precipitation. However, retrieval accuracy has been shown to be degraded in weak-to-moderate winds coupled with heavy precipitation. In particular, winds are typically overestimated in such conditions. A recent project funded by the U.S. Weather Research Program Joint Hurricane Testbed quantified this bias over the expected range of winds and rain rates in hurricanes. In general, the bias was found to be largest at the weakest wind speeds and heaviest precipitation, and diminishes as surface winds increase. At minimal hurricane-force winds ($V_{\text{max}} = 33 \text{ m s}^{-1}$), the mean bias is not more than $\sim 2.5 \text{ m s}^{-1}$, and decreases to near zero by $\sim 50 \text{ m s}^{-1}$. A bias correction function (Klotz and Uhlhorn 2013, manuscript submitted to Mon. Wea. Rev.) based on these results is applied to the SFMR surface wind data. <table> <thead> <tr> <th>Year</th> <th>Storm (No. of flights)</th> </tr> </thead> <tbody> <tr> <td>1998</td> <td>Bonnie (3), Earl (1), Georges (2)</td> </tr> <tr> <td>1999</td> <td>Bret (1), Dennis (2), Floyd (2), Lenny (1)</td> </tr> <tr> <td>2001</td> <td>Humberto (2)</td> </tr> <tr> <td>2002</td> <td>Isidore (1), Lili (2)</td> </tr> <tr> <td>2003</td> <td>Fabian (1), Isabel (2)</td> </tr> <tr> <td>2004</td> <td>Frances (6), Ivan (6), Jeanne (1)</td> </tr> <tr> <td>2005</td> <td>Katrina (4), Rita (5), Wilma (1)</td> </tr> <tr> <td>2006</td> <td>Helene (2)</td> </tr> <tr> <td>2007</td> <td>Felix (3)</td> </tr> <tr> <td>2008</td> <td>Dolly (1), Gustav (7), Ike (8), Paloma (3)</td> </tr> <tr> <td>2009</td> <td>Bill (5)</td> </tr> <tr> <td>2010</td> <td>Alex (1), Danielle (2), Earl (18), Igor (6), Karl (3), Paula (1), Tomas (3)</td> </tr> <tr> <td>2011</td> <td>Irene (14), Katia (1), Maria (1), Rina (6)</td> </tr> <tr> <td>Total</td> <td>35 (128)</td> </tr> </tbody> </table> Objective wind field analysis Like aircraft flight-level winds, surface wind speeds measured by SFMR are obtained periodically at high frequency [typically, 1 Hz; Uhlhorn et al. (2007)] along the flight track. Historically, hurricane reconnaissance flight patterns have consisted of radial legs to and from the storm center (e.g., Sheets 2003), a practice that generally continues today. Thus, data sampling is dense in the radial dimension, but comparatively fewer data in the azimuthal dimension are available, especially as radius increases, with the exception of downwind legs connecting successive radial legs. From this type of sampling pattern, a semispectral analysis is a convenient representation of the wind field, with the radial dimension represented in physical space and the azimuthal dimension in wavenumber space. The analysis system considers the scales of quantities resolved by the observation network (i.e., aircraft). Considering the SFMR radiative footprint at typical aircraft ground speeds, each wind observation represents an approximately 3-km spatial scale along the flight track, and around 1 km in the cross-track dimension (Uhlhorn and Nolan 2012). Since each observation is spaced 30 s (~3.5 km) apart, there is only around 0.5 km of latency between observations. The observation scales lead to the design of the analysis field. From an individual flight, each radial leg (inbound or outbound from the center) is identified. For example, a single “figure 4” pattern consists of four individual radial legs. For each leg, an RMW ($R_{\text{max}}$) is found at both the surface and flight levels, and used to normalize the observed distance $r$ from the storm center ($r^* = r/R_{\text{max}}$). Each radial leg is then interpolated onto a normalized grid, whose spacing ($\Delta r^*$) depends on the average RMW to maintain consistency with the approximately 3-km radial sampling. A similar methodology was used to develop composite radial profiles of flight-level winds (Mallen et al. 2005). As an example, an average RMW of 30 km suggests $\Delta r^* = 0.1$. Since radial legs typically extend 105 n mi (~194 km) from the storm center, wind observations in this example would be available radially outward to $r^* \approx 6.5$. The advantage of this method is that the WN0 component is maximized at $r^* = 1$ by eliminating errors due to storm-center location uncertainty. A disadvantage is that real asymmetries resulting from elliptical vortex structure or wind center displacement are not captured. An example of observational data input into the analysis is shown in Fig. 4, from a flight in Hurricane Katrina on 28 August 2005. The georeferenced flight track (Fig. 4a) consists of a rotated figure-4 pattern (with one repeated final fifth radial leg), in which eight azimuths are sampled over the flight. Surface and 700-mb flight-level wind speeds over the approximately 9-h flight (Fig. 4b) show the five eye penetrations. For analysis purposes, the first four radial inbound–outbound legs are used (Fig. 4c). Wind speeds are plotted as a function of normalized radial distance from the storm center (Fig. 4d), based on the storm track from NHC supplemented with additional storm-center locations provided by the Hurricane Research Division, and RMWs determined for each of the legs at both the surface and flight levels. The analysis methodology has been previously applied to Hurricane Rita (2005) for winds at $r^* = 1$ (Rogers and Uhlhorn 2008) and, here, is generalized to all radii at which data are routinely available. Based on the storm center found from the wind speed minimum for each pass, the azimuthal angle $\Lambda$ measured clockwise relative to the storm-motion direction is computed for each observation. These angles are also interpolated onto the same normalized radial ($r^*$) grid. At each normalized radius, a set (typically four, six, or eight, depending on flight pattern) of wind speed observations at corresponding azimuth angles is obtained. A harmonic function of the form $$S(r^*, \lambda) = A_{s0}(r^*) + A_{s1}(r^*) \cos[\lambda - \phi_{s1}(r^*)] + \epsilon$$ \hfill (1) is fit to the observations using a least squares method. At each radius, a set of three parameters [WN0 axisymmetric mean ($A_{s0}$), WN1 asymmetric amplitude ($A_{s1}$), and phase ($\phi_{s1}$)] describes the WN0 + 1 two-dimensional wind field $S$ at either the surface or flight level, with an associated residual error $\epsilon$. As a matter of the least squares principle, each parameter itself has an associated error, which is also computed. The maximum WN0 + 1 wind speed is defined to be located at ($r^*, \lambda$) = (1, $\phi_{s1}$). As a result, the wind fields at the surface and flight level may be reconstructed from the coefficients as a function of normalized radius. Figure 5 shows WN0 + 1 wind fields for the Hurricane Katrina descriptive example, where the mean RMWs at the surface (24.5 km) and flight level (31.1 km) are used in the conversion back to the physical radial distance. d. Analysis limitations In some situations, for example when a cyclone is being investigated for potential development (an INVEST mission), the semispectral analysis method described above does not lend itself to accurate description of the wind field. In such cases, the vortical wind field structure is perhaps not well defined, and the flight pattern may not consist of regularly spaced radial legs that are convenient for a polar analysis. It may be more appropriate to apply a traditional successive-correction objective analysis (e.g., Barnes 1964) or optimal interpolation (e.g., Bergman 1979) in these situations, from which the WN0 + 1 could subsequently be extracted. To avoid these potential issues, analyses are restricted to TCs minimally of hurricane strength in this study. For a number of reasons, the analysis procedure is truncated at WN1. Often, reconnaissance missions consist of one single figure-4 pattern, which provides observations at four azimuthal locations. To unambiguously determine the WN0 mean, as well as WN1 amplitude and phase, a minimum of three observations around the storm is required, in which case WN1 is the highest resolvable asymmetric component. Second, the analysis is synoptic in nature, as temporal evolution of the field over the observation period (typically a few hours) is not considered. Higher-order components are often not stationary, for example, embedded mesocyclones (e.g., Kossin and Schubert 2001). These features generally propagate around the eyewall relative to the mean flow and may quickly grow and decay; therefore, the amplitude and phase of these features cannot be estimated with a high degree of confidence. Also, since their propagation is not likely to coincide with the aircraft sampling, their energy may be aliased into lower wavenumbers. As an example of the potential impact of higher-order harmonics on a WN0 + 1 analysis, the previous example from Katrina is examined further. With eight wind observations around the eyewall over the flight, theoretically up to WN3 may be resolved assuming a stationary field composed of linear, noninteractive spectral components. A Fourier decomposition is carried out to third-order harmonic at the RMW to quantify the impact on the WN1 estimate when higher-order terms are considered. Figure 6 shows three representations of the wind speed at \( r^* = 1 \): wavenumbers 0 through 1 (WN0 + 1), wavenumbers 0 through 2 (WN0 + 1 + 2), and wavenumbers 0 through 3 (WN0 + 1 + 2 + 3). As higher harmonics are considered, the fit to the observations improves. However, the WN1 amplitude \( A_1 \) grows, and the phase \( \phi_1 \) shifts. The amplitude growth is contrary to expectations under an energy-conservation constraint, since attributing total energy progressively to higher harmonics should result in a decrease in lower-harmonic energy. It is possible that temporal aliasing of nonstationary harmonics, for example, as manifested in eyewall mesocyclones, is artificially contributing to the estimated WN1 asymmetry. This example is rather extreme as hurricanes with similar inner-core annular structure (Knaff et al. 2003) have been shown to be particularly supportive of energetic higher-order, subvortex-scale embedded circulations. Still, in this particular case the maximum WN0 + 1 is \( \sim 93\% \) of the highest observed surface wind speed of 70.1 m s\(^{-1}\), indicating its dominant contribution. It is anticipated that such artifacts are not generally as detrimental to the low-wavenumber analysis. Future instrumentation such as the Hurricane Imaging Radiometer (HIRAD) on NASA’s GlobalHawk aircraft (Braun et al. 2013), alternative sampling patterns, and high-resolution modeling studies could help elucidate the impact of high-wavenumber components on a low-wavenumber wind field analysis. 3. Results a. Mean and asymmetric structure versus radius Composite mean and asymmetric wind fields at the surface and flight level are constructed from the 128 analyses. The vast majority (>90%) of flight-level wind data are obtained at the 700-mb (~3 km) standard reconnaissance altitude, and all flights are between 2.4 and 3.6 km, or ~760 and ~640 mb, respectively. Symmetric mean (WN0), and asymmetric wavenumber-1 (WN1) amplitude ($A_{s1}$) and phase ($\phi_{s1}$), are plotted as functions of normalized radius ($r^*$) based on the RMWs at either the surface or flight level, as necessary (Fig. 7). Therefore, the wind maxima at both the surface and flight levels are located at $r^* = 1$, although physically the flight-level peak is often found radially outward of the surface peak as a result of eyewall slope (Powell et al. 2009; Stern and Nolan 2009). Outside of the inner core ($r^* \approx 2$), the average surface WN0 wind speed is around 75%–80% of the flight-level value, and this ratio increases to around 90% at the surface RMW (Fig. 7a). Similar results have previously been computed by analytical models (Kepert 2001), and have been observed for reductions of maximum flight-level winds to the surface (Franklin et al. 2003). The composite axisymmetric surface wind decays at a faster rate radially outward from the RMW ($\sim r^{-0.35}$) than at flight level ($\sim r^{-0.25}$), although there is significant case-to-case variability that is possibly due to other factors, including intensity (Mallen et al. 2005), intensity tendency, latitude, and translation speed (Holland et al. 2010). Radially inward of the surface RMW, the surface wind speed approaches 100% of the flight-level wind, due to eyewall slope, as is typically observed (e.g., Powell et al. 2009, Fig. 1). Averaged over the sample, the WN1 asymmetry amplitude (Fig. 7b) is around 50% higher at the flight level than at the surface, particularly between 1 < $r^*$ < 5. At greater radii, the amplitude difference becomes statistically insignificant. Radially inward of the RMW, there is an apparent increase in surface asymmetry amplitude. However, the asymmetry becomes more difficult to diagnose here, due to both error in the reference storm center location, as well as possible higher-order nonstationary asymmetries being aliased into the low-wavenumber structure. Thus, the accuracy of asymmetry results inside of the RMW is somewhat suspect at present. The WN1 asymmetry phase is defined here as the storm-motion-relative azimuthal location of the asymmetry maximum (i.e., where $\lambda = \phi_{s1}$). The phase (Fig. 7c) is generally located close to directly right of storm motion at the flight level, and the surface WN1 maximum is typically found in the right-front quadrant, ~40$^\circ$ to the right of the storm motion as previously found in a smaller sample (Uhlhorn et al. 2007). Therefore, there is generally an upwind rotation of wind maximum from the surface to the flight level. As for the amplitude, the apparent downwind phase rotation at both the flight level and the surface inside of the RMW may be artificial. b. Asymmetry dependence on storm motion The dependence of surface and flight-level wind asymmetries on storm motion is estimated, focusing on the asymmetries at the RMW. Fourier coefficients ($A_{s1}$ and $\phi_{s1}$) derived from the 128 analyses are plotted as functions of $V_{\text{storm}}$ (Fig. 8). Linear regression fits ($a + bV_{\text{storm}}$) are computed to estimate the motion dependence. The WN1 asymmetry dependence is apparently manifested in different ways at the surface and at flight level. The surface $A_{s1}$ has little, if any, dependence... on storm motion speed, and $\phi_{s1}$ has a small, but statistically significant, tendency to rotate upwind as motion increases. At flight level, a large increase in amplitude with $V_{\text{storm}}$ is found, with little phase shift as motion increases. Table 2 lists the coefficients of linear fits plotted in Fig. 8. It has typically been assumed that the surface wind field becomes more asymmetric as storm motion increases, and an extrapolation of flight-level winds to the surface would reflect this. For example, parametric wind models used for forcing storm surge predictions often simply add the storm motion vector to the symmetric wind field, resulting in an amplitude $A_{s1} = V_{\text{storm}}$, with constant phase $\phi_{s1} = 90^\circ$. Over the hurricane sample assembled here, this would appear to be an incorrect assumption. However, due to an asymmetry phase shift, an anemometer measuring the wind speed at a location exactly $90^\circ$ to the right of motion at the RMW would indicate a higher wind speed for a faster-moving storm for the same WN0 + WN1 wind. Although the SFMR has assumed a prominent role in helping forecasters diagnose hurricane intensity when aircraft reconnaissance data are available, flight-level winds remain an important tool for determining intensity, as well as providing a basis for detecting occasional anomalous SFMR behavior. In the absence of direct surface wind data during hurricanes, near-surface winds have been estimated from flight-level wind data using a standard wind-reduction factor (Franklin et al. 2003). Powell et al. (2009) examined the relationship between observed surface and flight-level maximum wind speeds using SFMR wind data within a composite framework and found that the ratio of surface-to-flight-level wind speeds (simply, “ratio”) was typically larger to the left of storm motion. In this previous study, the amplitude of the WN1 ratio asymmetry was estimated to be approximately $5\%$; that is, the ratio was $\sim 10\%$ larger on the left side of the storm than on the right side. Furthermore, a small asymmetry amplification with increased storm motion speed was found, although no indication of statistical significance was provided. Wind speed ratio asymmetries are examined at the RMW for the 128 sample cases. The WN0 + 1 asymmetry model [Eq. (1)] is fit to the observed ratio as a function of the azimuth to estimate amplitude ($A_{r1}$) and phase ($\phi_{r1}$), and frequency histograms are plotted in Fig. 9. On average, the maximum ratio is found in the left-front quadrant relative to storm motion (mean $\phi_{r1} = -69^\circ$), but does not significantly rotate with increased storm motion speed (not shown). The mean asymmetry amplitude is $A_{r1} = 11\%$, and also does not change significantly with storm motion speed. --- Fig. 7. Composite (a) WN0 wind speed (m s$^{-1}$), (b) WN1 amplitude (m s$^{-1}$), and (c) WN1 motion-relative phase ($^\circ$) at the surface (black) and flight level (red) as functions of normalized radius ($r^*$). Solid lines are means for the $n = 128$ sample, thick dashed lines are 95% confidence intervals on the means, and dotted lines are one standard deviation. c. Asymmetry dependence on environmental shear The potential impact of environmental shear on wind asymmetries at the RMW is examined after removing the storm-motion-induced asymmetry. Customarily, storm-relative winds are computed by vector subtraction of the storm motion from the wind, which is not directly possible here since the SFMR does not observe wind direction. To avoid this problem, the empirically derived asymmetries in Table 2 are first subtracted from the wind speeds, and data are then rotated to a shear-direction-relative coordinate system, where $\lambda = 0^\circ$ is now oriented in the DS direction. The harmonic least squares fitting proceeds as before to estimate Fourier coefficients describing the asymmetry as a function of environmental shear magnitude ($V_{\text{shear}}$). Figure 10 shows the coefficients at both the surface and flight level. After removing the estimated motion-induced asymmetry, a dependence on shear magnitude is found, particularly at the surface. The amplitude and phase dependencies (Fig. 10) indicate the most significant impact of environmental shear on the surface wind asymmetry is a cyclonic upshear rotation of the wind maximum—from the DS to LS locations—with increasing shear magnitude. A small rotation is also found at flight level, but the trend is not statistically significant. The average asymmetry amplitudes at both surface and flight level are around 3–5 m s$^{-1}$, and are statistically significant from zero at the 95% confidence level. The residual shear-relative amplitude is a significant component of the total observed asymmetry, which previously was found to be $\sim 5$ m s$^{-1}$ at the surface. Table 3 lists the linear regression coefficients for the fits shown in Fig. 10. As was done for storm motion, the impact of environmental shear on residual surface wind reduction from flight level is examined (Fig. 11). For this sample, | TABLE 2. Linear regression coefficients for asymmetry vs motion speed relationships $[[A_1, \phi_1] = a + bV_{\text{storm}}]$ at surface and flight levels. Values are estimates and 95% confidence intervals, with boldface type indicating statistical significance. Phase angles are clockwise relative to storm motion. | |---|---|---|---| | $A_1$ | $\phi_1$ | | Surface | Flight level | Surface | Flight level | | $a$ | $b$ | $a$ | $b$ | | $4.56 \pm 1.30$ | $0.07 \pm 0.24$ | $3.61 \pm 1.38$ | $0.71 \pm 0.25$ | | $9.85 \pm 22.27$ | $4.52 \pm 4.12$ | $56.41 \pm 13.42$ | $2.22 \pm 2.44$ | there appears to be no significant amplification of the surface-to-flight-level ratio asymmetry; however, there is a significant rotation of the asymmetry with increased shear. Over the range of observed shear from 0 to 15 m s\(^{-1}\), the ratio asymmetry phase rotates from the DS direction to around 100° left of shear. d. Asymmetry relationship to shear-relative motion Although the estimated impact of storm motion on wind speed asymmetries was removed prior to examining the relationship of asymmetries to shear, it is not yet clear that the observed left-of-shear asymmetry generally Fig. 9. Surface-to-flight-level wind speed ratio WN1 asymmetry (a) amplitude and (b) phase frequency histograms. Amplitude is dimensionless, and phase is in degrees azimuth clockwise relative to storm motion. Fig. 10. As in Fig. 8, but plotted vs shear magnitude (m s\(^{-1}\)) after removing storm-motion-induced asymmetry. Phase angle (°) is clockwise azimuth relative to shear direction. holds over all motion versus shear configurations. The relative impacts of motion and shear on convective asymmetries have previously been examined, with evidence pointing to a shear dominance (Corbosiero and Molinari 2003). Referring back to Fig. 3, there is a systematic relationship between motion and shear directions in the sample examined, as typically the shear heading is directed across the storm motion from left to right. This is consistent with a NW-traveling hurricane encountering an environmental shear from the SW. Under this configuration, a storm’s right-front quadrant relative to motion is also the downshear-left quadrant relative to shear direction. Thus, the surface wind maxima relative to both motion and shear directions may be found at similar locations, on average. To demonstrate that the left-of-shear wind maximum is a general result, the sample is stratified according to shear-relative motion ($u_{\text{5u}} < u < 2u_{\text{storm}}$), whose sample distribution was previously shown in Fig. 3c, depending on whether motion is downshear (DSHR), right of shear (RSHR), upshear (USHR), or left of shear (LSHR). The DSHR group ($n = 36$) contains storms traveling $-45^\circ < \Delta \theta < +45^\circ$, the RSHR group ($n = 36$) contains storms traveling $+45^\circ < \Delta \theta < +135^\circ$, the USHR group ($n = 27$) contains storms traveling $\Delta \theta < -135^\circ$ or $> +135^\circ$, and the LSHR group ($n = 39$) contains storms traveling $-135^\circ < \Delta \theta < -45^\circ$. The mean characteristics of each subsample group are presented in Fig. 12. Note that mean motion and shear values are computed as vector averages, while mean direction differences are scalar averages. Generally, the DSHR group of storms is the most strongly sheared and has the most northward motion component, while the RSHR group is most weakly sheared and has the most westward motion component. The differences in motion speed among all groups are not statistically significant, while shear magnitude differences are marginally significant between the DSHR and RSHR groups. Shear-relative motion direction is controlled far more by the shear than the motion. Figure 13 shows frequency histograms of the surface wind speed asymmetry $W_{11}$ amplitude and phase for each of the four shear-relative motion groups. Differences in amplitude and phase among each of the groups are not statistically significant. In all cases, the average residual asymmetry maximum is found in a downshear-left location. The asymmetric distribution of the surface-to-flight-level wind speed ratio is shown in Fig. 14 for each individual shear-relative motion group. The ratio asymmetry generally reflects the surface wind speed asymmetry, indicating that the largest ratios (after removing the motion dependence) are typically found in the DS to LS directions, in all cases. With the smaller sample sizes after stratifying according to shear-relative motion, quantifying asymmetry dependence on shear magnitude individually for each group remains difficult. However, it is clear that the environmental flow field (as represented here by the vertical shear) through which a storm moves may impact the surface wind asymmetry and, therefore, the asymmetric relationship between winds measured at the surface and well above the TC boundary layer. <table> <thead> <tr> <th>Surface</th> <th>Flight level</th> </tr> </thead> <tbody> <tr> <td>$a$</td> <td>$b$</td> </tr> <tr> <td>$A_1$</td> <td>$3.37 \pm 0.89$</td> </tr> <tr> <td>$\phi_1$</td> <td>$-11.78 \pm 19.08$</td> </tr> </tbody> </table> **Table 3.** As in Table 2, but for asymmetry vs shear magnitude after removing motion dependencies. Phase angles are clockwise relative to shear direction. Unauthenticated | Downloaded 12/23/22 05:59 AM UTC 4. Case study: Hurricane Earl a. General evolution The wind field response to an evolving environmental shear is examined based on extensive aircraft observations obtained during Hurricane Earl (2010) throughout much of its life cycle. In particular, research aircraft missions were conducted roughly every 12 h over a 5-day period during rapid intensification, eyewall replacement, reintensification, and decay toward an extratropical cyclone. Additionally, several operational reconnaissance flights were executed. In all, a total of 18 SFMR surface and flight-level wind analyses were constructed between 29 August and 4 September 2010 while Earl was classified as a hurricane. Earl’s track over the period of interest is shown in Fig. 15, and time series of best track intensity, SFMR-observed surface RMW, storm motion, and shear vectors are shown in Fig. 16. The storm motion speed was a fairly steady ~5–7 m s⁻¹ over most of the period, as Earl progressed on a gradual recurvature, from a westward to a northward heading. Over this period, the storm rapidly intensified between 29 and 30 August, reaching an initial peak intensity of nearly 60 m s⁻¹ (115 kt, 1 kt = 0.51 m s⁻¹), while the RMW contracted from >50 to ~20 km (Fig. 16a). On 31 August, Earl... began an eyewall-replacement cycle, with a slight weakening and increase in the RMW. The storm re-intensified to its maximum intensity of 64 m s$^{-1}$ (125 kt) on 2 September, before beginning a gradual weakening and wind field expansion. Early in the period, the shear was weak and from the NE, when Earl rapidly intensified. The shear magnitude increased subsequent to the initial intensification (Fig. 16b), while the direction rotated through easterly to become southerly when eyewall replacement began (Fig. 16c). After this, the shear magnitude weakened slightly, and the direction remained relatively constant for the remainder of the observation period to 4 September. The shear-relative motion direction ($\Delta \theta$) executed nearly a continuous full cycle, rotating at an average rate of $-60^\circ$ day$^{-1}$ over this 6-day period (Fig. 16d). Surface and flight-level wind field evolutions derived from the Fourier analyses are shown in Fig. 17 for each of 5 days (30 August–3 September) at 0000 UTC. Fields are plotted relative to storm motion direction, as indicated by black arrows. The motion-relative shear vectors are also plotted as white arrows. Beginning on 30 August, a fairly weak shear is directed across the storm track from right to left, and becomes stronger and rotates counterclockwise to align closely with the storm motion direction by the end of the period. The flight-level asymmetry is mostly located to the right of track, with a weak counterclockwise rotation in time. The surface wind maximum (indicated by the plus sign) begins on 30 August to the right of track when the shear is weaker, and rotates counterclockwise in time to the front of the storm by 3 September. When the shear is sufficiently strong from 31 August on, the surface asymmetry maximum maintains a downshear to downshear-left location, deviating from the expected motion-induced asymmetry. The flight-level peak remains more closely locked to the motion, although some small variation is observed. A similar evolution was noted in Hurricane Rita over a 3-day period (Rogers and Uhlhorn 2008), in which the shear steadily increased and rotated counterclockwise in time, while the surface wind asymmetry changed from right of storm motion to being in front of the storm. ![Fig. 13. Frequency distributions of surface WN1 asymmetry (top) amplitude and (bottom) phase for each shear-relative motion group. Columns are (left) DSHR, (middle left) RSHR, (middle right) USHR, and (right) LSHR. Sample sizes, means with 95% confidence intervals, and medians are indicated.](image-url) b. Asymmetry evolution The WN0 + 1 analyses at the surface and flight level are interpolated in time every 12 h, beginning at 1200 UTC 29 August, through 1200 UTC 3 September. Figure 18 shows surface and flight-level WN0 means, and WN1 amplitudes and motion-relative phases as functions of radius and time over the observation period. The dual WN0 maxima at both surface and flight levels on 31 August and 2 September are clearly evident, along with the local intensity minimum associated with eyewall replacement on 1 September. Associated with the replacement is a large increase in asymmetry, particularly at the flight level. Also, a significant asymmetry at the surface appears at \( r^* \) late during the period on 3 September, suggesting a developing outer wind maximum. At the flight level, the asymmetry phase varies by no more than \( 30^\circ \), and is generally right of motion at all radii throughout. At the surface, however, the phase rotates counterclockwise in time by more than \( 60^\circ \) at the RMW from right of motion to in front of the storm; these changes are even more evident at larger radii. Since these analyses are relative to storm motion direction, and storm motion speed only varies by around \( 2 \text{ m s}^{-1} \) over this period, changes in asymmetry may be interpreted as a result of mechanisms other than storm motion. The WN1 asymmetry amplitude at the RMW is shown in Fig. 19. The evolution (Fig. 19a) suggests an amplifying asymmetry from early in the period, to a peak... around the time of eyewall replacement, and then a gradual return to a more symmetric wind field later in time. At both the surface and flight level, there is little relationship between amplitude and $V_{\text{storm}}$ (Fig. 19b), as linear trends are not significant, although the motion does not vary a great deal, as previously noted. In contrast, there is a strong relationship between the amplitude and $V_{\text{shr}}$ (Fig. 19b) for this particular storm. Linear trends are significant at the 95% confidence level, and correlation coefficients are $r^2 = 0.61$ and $0.87$ at the surface and flight levels, respectively. The ratio of surface-to-flight-level wind speed $W_{\text{N1}}$ asymmetry is tracked through Earl’s life cycle. As the storm progressed, the location of the flight-level wind maximum remained to the right of motion, while the surface maximum rotated counterclockwise from right to forward of motion, maintaining a downshear-left position as the shear vector rotated with time. To emphasize the potential shear control on the asymmetry, the reduction ratio phases are computed relative to storm motion direction and plotted versus $V_{\text{storm}}$ (Fig. 19a), and relative to shear direction plotted versus $V_{\text{shr}}$ (Fig. 19b). Motion-relative phase is typically to the left of motion, as previously found by Powell et al. (2009), and shown in Fig. 9b. In Earl, however, there is no significant dependence on $V_{\text{storm}}$. In sharp contrast, the shear-relative reduction asymmetry phase has a strong dependence on $V_{\text{shr}}$, consistent with the results for the full sample (Fig. 11), suggesting the counterclockwise rotation from the DS position to LS, as the shear magnitude increases. 5. Discussion A couple of recent studies have found evidence for an environmental shear impact on west Pacific typhoon near-surface wind $W_{\text{N1}}$ asymmetries (Ueno and Kunii 2009; Ueno and Bessho 2011). In addition, Ueno and Kunii (2009) suggested a link between the eyewall vertical velocity asymmetry and the boundary layer tangential wind asymmetry. Overall, their results suggested a preferential downshear-left azimuthal location for the storm-relative maximum wind, and when the shear was strong and aligned with the motion, a left-of-motion earth-relative wind maximum could be found. In the present study, 28 out of the 128 (23%) total analyzed cases indicated a left-of-motion surface wind maximum (Fig. 8b). When broken down by shear-relative motion direction, 41% of the DSHR cases contained a left-of-motion maximum. In contrast, only 18% of both the RSHR and USHR cases showed the maximum located left of motion, and 11% of the LSHR cases contained Fig. 17. Hurricane Earl wind speed (m s$^{-1}$) analyses at (left) the surface and (right) flight level, corresponding to 0000 UTC on date indicated (month/day). Analyses are oriented with respect to storm motion direction, with across- (along-) track distance (km) labeled along the x (y) axis. Black arrows show the storm motion vector, and white arrows the shear vector. Range rings indicate magnitude (m s$^{-1}$) at 2.5 m s$^{-1}$ intervals, or $\frac{1}{10}$ axis labels. a left-of-motion earth-relative wind speed maximum. Additionally, the DSHR, left-of-motion wind maximum group is also the most strongly sheared, on average. These results imply that the horizontal surface wind field in TCs influenced by shear may deviate systematically from the expected motion-induced asymmetric structure (Shapiro 1983; Kepert 2001; Kepert and Wang 2001). Parametric wind fields designed to accurately capture low-wavenumber asymmetry should consider the important shear impact. Numerous observational studies have sought to relate environmental shear to convection asymmetries in TCs from airborne radar reflectivity (e.g., Reasor et al. 2000; Black et al. 2002; Reasor and Eastin 2012), spaceborne passive microwave measurements (e.g., Knaff et al. 2004; Chen et al. 2006; Cecil 2007; Wingo and Cecil 2010), and lightning distribution (Corbosiero and Molinari 2002, 2003), with the common conclusion that an inner-core precipitation maximum is typically found in a downshear-left location. Additionally, observations of airborne Doppler radar–derived vertical velocity (e.g., Black et al. 2002; Reasor et al. 2009, 2013) indicate the main updraft maximum is typically located downshear and in the direction of eyewall tilt. Modeling studies have shown the maximum storm-relative low-level radial inflow to also be located generally downshear (Bender 1997; Rogers et al. 2003; Wu et al. 2006; Braun and Wu 2007; Davis et al. 2008). From a storm-relative vantage point, the tangential and radial wind component asymmetries are in quadrature (Schwendike and Kepert 2008; Ueno and Bessho 2011), with the tangential wind maximum $\frac{\pi}{2}$ rad clockwise from the radial wind maximum. From continuity, the low-level radial flow and vertical velocity asymmetries are $\pi$ rad out of phase (i.e., the radial flow maximum is upshear). When the environmental shear is sufficient, the main updraft maximum becomes more isolated in the downshear position, and from this analysis, the tangential wind maximum is therefore located left of shear. It can be easily shown that the wind speed WN1 asymmetry phase ($\phi_{s1}$) is related to the radial component asymmetry by $$\phi_{s1} = \cos^{-1}\left(\frac{A_{u0}A_{u1}}{A_{s0}A_{s1}}\right),$$ (2) where $A_{u0}$, $A_{s0}$, $A_{u1}$, and $A_{s1}$ are the axisymmetric mean and WN1 amplitudes of radial wind, respectively. Based on results in this study along with recent observations of TC inflow asymmetries derived from dropwindsondes, the expected wind speed asymmetry phase may be estimated. As found by Zhang and Uhlhorn (2012), the axisymmetric mean storm-relative inflow angle at the RMW is $-20.2^\circ \pm 2.2^\circ$ (95% confidence) for a typical hurricane, which results in $A_{u0}/A_{s0} \approx -0.34$. Also, the storm-relative inflow angle WN1 amplitude at the RMW was found to be $9.2^\circ \pm 2.0^\circ$. For a mean wind speed of $A_{s0} = 40$ m s$^{-1}$, the radial wind asymmetry amplitude is $A_{u1} \approx 7.4$ m s$^{-1}$ (Zhang and Uhlhorn, 2012). Results from the present study indicate $A_{s1} \approx 4.1$ m s$^{-1}$ (see Fig. 13), suggesting the ratio $A_{u1}/A_{s1} \approx 1.8$. Substituting these values into Eq. (2) results in an expected near-surface wind WN1 asymmetry phase relative to the radial flow maximum of $\phi_{s1} \approx +128^\circ$, or $-52^\circ$ relative to the inflow maximum. Assuming the inflow and shear directions are collocated, this places the wind speed maximum in the downshear-left quadrant, in agreement with the observations here. Based on this simple interpretation, the convective and near-surface kinematic asymmetries appear to be interrelated in a highly systematic way, which the vertical shear exposes when sufficiently strong. 6. Summary and conclusions Based on an analysis of SFMR surface and in situ flight-level wind data obtained on 128 hurricane aircraft missions, the asymmetric wind structure at the RMW in response to motion and 850–200-mb environmental shear is documented. The analysis consists of an azimuthal WN0 + 1 Fourier decomposition from high radial resolution wind speed observations, designed to yield the WN0 symmetric mean, and WN1 amplitude and phase, as functions of radial distance from the storm center. The important findings of this study are as follows: - Storm motion impacts flight-level and surface wind asymmetries differently. At flight level, amplitude increases in proportion to motion speed, while phase is locked nearly directly to the right of motion direction, independent of speed. At the surface, amplitude is nearly constant, while phase rotates from front to right of motion direction as speed increases. - Relative to storm motion direction, the asymmetry amplitude of the surface-to-flight-level wind speed (slant) ratio at the RMW is broadly distributed with a median value around 0.1 (i.e., the ratio typically varies by ~20% around the eyewall), while the maximum location is found to the left of the motion. No ratio asymmetry dependence on motion is found. - After accounting for, and removing, the motion dependence, a residual asymmetry component relative to the shear direction is found, especially at the surface. A significant phase rotation from downshear to left of shear with increased shear magnitude is observed, regardless of the relationship between motion and shear directions. The flight-level phase response is comparatively weaker. - The evolution of wind asymmetries in Hurricane Earl (2010) over a 5-day period clearly shows the response of the total, motion plus shear, impact. The flight-level wind maximum generally remains to the right of the storm track over the period while the shear increases. The surface wind maximum begins right of track early in the period and, as shear increases, rotates counterclockwise, remaining to the left of shear direction. As a result of this gradual phase separation, the surface-to-flight-level wind speed ratio maximum at the RMW has little relationship with storm motion speed ($r^2 = 0.05$), and a strong relationship with shear magnitude ($r^2 = 0.62$). These results appear to support recent conclusions about shear impacts on typhoon asymmetries, which find that a left-of-shear direction storm-relative wind maximum is to be expected. When the shear is sufficiently strong and roughly aligned with the motion direction, the motion and shear-induced asymmetries can combine to yield a left-of-motion earth-relative wind maximum location. The results of this study are generally supportive of these findings. Because the SFMR only measures the wind speed, observations of near-surface radial and tangential wind asymmetries, and their relationships to vertical wind and convection asymmetric structure, have not been directly analyzed in this study. A more complete observational view of the surface to upper-tropospheric kinematics in sheared environments remains to be developed. Planned future efforts will involve combining the results found here with composite analyses of surface wind vector field asymmetries using GPS dropwindsonde data, and linking the results to Doppler radar-derived wind and thermodynamic fields. Acknowledgments. The authors would like to acknowledge John Kaplan, Drs. Sundararaman Gopalakrishnan, and Mark Powell (HRD), as well as two anonymous reviewers, for their comments and suggestions that significantly improved the manuscript. B. Klotz is partially supported through the Joint Hurricane Testbed and Hurricane Forecast Improvement Project. REFERENCES
2010-11-24 Female Development Amidst Dictatorship in Julia Alvarez's *In the Time of the Butterflies* and Mario Vargas Llosa's *La fiesta del Chivo* Serena Eileen Call *Brigham Young University - Provo* Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Spanish and Portuguese Language and Literature Commons BYU ScholarsArchive Citation Call, Serena Eileen, "Female Development Amidst Dictatorship in Julia Alvarez's *In the Time of the Butterflies* and Mario Vargas Llosa's *La fiesta del Chivo*" (2010). *All Theses and Dissertations*. 2465. https://scholarsarchive.byu.edu/etd/2465 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in All Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact scholarsarchive@byu.edu, ellen_amatangelo@byu.edu. Female Development amidst Dictatorship in Julia Alvarez’s *In the Time of the Butterflies* and Mario Vargas Llosa’s *La fiesta del Chivo* Serena E. Jensen A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Arts Douglas J. Weatherford, Chair Russell M. Cluff David Laraway Department of Spanish and Portuguese Brigham Young University December 2010 Copyright © 2010 Serena E. Jensen All Rights Reserved ABSTRACT Female Development amidst Dictatorship in Julia Alvarez’s In the Time of the Butterflies and Mario Vargas Llosa’s La fiesta del Chivo Serena E. Jensen Department of Spanish and Portuguese Master of Arts Dominican dictator Rafael Trujillo (ruled 1930-1961) developed the reputation as one of the most violent and oppressive leaders of the Western Hemisphere in his thirty-one years of power. Authors Julia Alvarez and Mario Vargas Llosa provide insight into the effects of Trujillo's infamy by sharing the stories of Dominican women. In Alvarez’s novel, In the Time of the Butterflies, the Dominican-American author fictionalizes the lives of the Mirabal sisters, historical women who were assassinated in 1961 for their involvement in the anti-Trujillo movement. Likewise, Vargas Llosa centers much of his novel, La fiesta del Chivo, on the life of Urania Cabral, a fictional female character who is raped by Trujillo at the age of fourteen. Both the Mirabals and Urania grow up amidst dictatorship and Alvarez and Vargas Llosa frequently focus on their characters’ growth as they progress from childhood and adolescence into adulthood. This formative time in the protagonists’ lives is often impacted by Trujillo and his actions. In particular, Alvarez and Vargas Llosa emphasize the unique process of female identity formation as a means of highlighting the cruelty of the Trujillo dictatorship. Female development is often described as a process that focuses on connection and relationships to others. As a result, women often demonstrate a high ability to respond to the needs and feelings of the people in their lives. Alvarez’s depiction of the Mirabal sisters reflects these principles as her characters mature into strong women by learning the value of selflessly caring for others. The Mirabals’ concern for people contrasts to Trujillo’s character, which Alvarez portrays as violent, selfish and petty. Conversely, Vargas Llosa’s protagonist experiences a traumatic event at the age of fourteen that severely inhibits her growth. As a result of Trujillo’s cruelty Urania loses her ability to connect with others and becomes cold and distant. Urania’s developmental obstacles reflect the debilitating effects dictatorship can have on individuals, and by extension, on a whole nation. In both In the Time of the Butterflies and La fiesta del Chivo the concept of female development shapes and informs the portrayal of Rafael Trujillo and his corrupt government. Keywords: In the Time of the Butterflies, La fiesta del Chivo, female development, Rafael Trujillo, Julia Alvarez, Mario Vargas Llosa ACKNOWLEDGEMENTS Throughout the challenging process of writing this thesis many friends, family members and mentors have provided invaluable support for which I am deeply grateful. I express thanks and gratitude to my husband Jake for the love and support he has constantly given during this past year. I also wish to thank my parents, Steve and Conni Call, for their encouragement throughout my life to pursue high educational goals and Cara Call and Donna Shin for reviewing drafts of this paper. Throughout all of my graduate studies, Dr. Douglas Weatherford has been a mentor and guide and I am profoundly grateful for his constant insight and patience. The lessons he has taught me during this process have had a profound impact on my life and will continue to do so. Finally, I express gratitude to the Spanish Department and the many professors and faculty members with whom I have had the privilege to work over the past five years and to Dr. Cluff and Dr. Laraway for their willingness to serve on my committee and their close readings of this thesis. TABLE OF CONTENTS INTRODUCTION........................................................................................................................................ 1 CHAPTER ONE: The Process of Becoming Butterflies: Female Development and Community in Julia Alvarez’s In the Time of the Butterflies ........................................................................................................... 13 CHAPTER TWO: “A mí, papá y Su Excelencia me volvieron un desierto”: Poor Fathering and Female Development in Mario Vargas Llosa’s La fiesta del Chivo .................................................................................................................. 34 CONCLUSION........................................................................................................................................ 56 WORKS CITED........................................................................................................................................ 60 INTRODUCTION In 1994, Julia Alvarez published *In the Time of the Butterflies*, a novel that examines the dictatorship of Rafael Leónidas Trujillo Molina (ruled 1930-1961) through the eyes of the four Mirabal sisters, three of whom would be assassinated for their political activism. Six years later, in 2000, Mario Vargas Llosa released his own historical novel, *La fiesta del Chivo*, which also addresses the Dominican Republic. Vargas Llosa brings to life the events of the thirty-one year Trujillo dictatorship through the fictional story of Urania Cabral. While Alvarez’s and Vargas Llosa’s accounts are very different, they do share several meaningful similarities. Although both authors critique the dictatorship, for example, Trujillo is not the protagonist of either novel. Instead, Alvarez and Vargas Llosa approach the Trujillo Era from a female perspective. Both the Mirabal sisters and Urania Cabral grow up during the *Trujillato*, and offer a glimpse into what life would be like for a young woman raised in a dictatorship. *In the Time of the Butterflies* and *La fiesta del Chivo* follow the development of their young protagonists from childhood and adolescence into adulthood. By employing multiple narrators, both Alvarez and Vargas Llosa give the reader a highly personalized view of the thoughts, growth, and progression of their characters. As the young girls in these novels mature, they experience a series of rites of passage, marking significant moments of --- 1 By noting the many similarities between *In the Time of the Butterflies* and *La fiesta del Chivo*, I do not wish to suggest that these novels do not have important differences. Alvarez and Vargas Llosa’s accounts differ significantly, especially in their tone, purpose, and characterization. Alvarez, for example, employs a witty style that may occasionally gloss over the seriousness of her characters’ situation. Vargas Llosa, in contrast, writes a macabre account of the Trujillo regime, depicting its extreme violence in an almost documentary style. *In the Time of the Butterflies* was also written with a different purpose than *La fiesta del Chivo*. Alvarez writes to describe the daily lives of the Mirabals, while Vargas Llosa’s novel is more concerned with political criticism. Finally, Alvarez’s characters are celebrated for standing up to Trujillo and becoming strong women of courage. In contrast, Urania struggles emotionally as a result of the abuse she endures and is significantly stunted in her development. These characteristics among others make *In the Time of the Butterflies* and *La fiesta del Chivo* very different accounts of the *Trujillato*. Nevertheless, the fact that both writers use female protagonists to examine the regime and are concerned with their characters’ growth and development is an important similarity that is deserving of attention. growth in their lives. In both novels, female development becomes an important lens through which each author examines the dictatorship. In *In the Time of the Butterflies*, the values the Mirabals learn in their youth contrast sharply to the dictator’s self-serving behavior. Conversely, Urania’s progression is significantly injured by Trujillo in her adolescence. In many ways she experiences truncated growth and is prevented from living a fulfilling life. Vargas Llosa uses Urania’s character as both a representative victim of the regime, as well as a metaphor for the abusive influences of dictatorship on a country. In both novels, the association between female development and dictatorship leads to a better understanding of the authors’ criticism of tyranny. Before addressing the issues of female identity formation raised in *In the Time of the Butterflies* and *La fiesta del Chivo*, I believe it useful to offer some background on Julia Alvarez and Mario Vargas Llosa and their relationship to the Dictator Novel. Both authors build on a large body of literature depicting Latin American dictators. Domingo Faustino Sarmiento’s *Facundo: Civilización y barbarie* (1845), a book which criticizes the rule of the Argentine caudillo Juan Manuel de Rosas, is often considered foundational to this popular genre. Other examples of Novels of Dictatorship include Miguel Ángel Asturias’s *El Señor Presidente* (1946), Juan Rulfo’s *Pedro Páramo* (1955), Augusto Roa Bastos’ *Yo el Supremo* (1974), Alejo Carpentier's *El recurso de método* (1975), and Gabriel García Márquez’s *El otoño del Patriarca* (1975). These novels reflect Latin America’s turbulent history with leaders who abuse their power. Ignacio López-Calvo explains, “The fact is that not only do dictators, as the personification of evil, offer superb literary possibilities, but they are also a crucial element for understanding the Latin American past, present and future” (6). Novels of Dictatorship depicting the Trujillo regime are particularly numerous. López-Calvo comments that “Rafael Leónidas Trujillo Molina, one of the most dreadful [Latin American dictators], seems to have captured the imagination of international writers like no other” (11). Rafael Trujillo is considered one of the worst tyrants in Latin American history. His reputation for cruelty was founded on many ruthless acts. In 1937, for example, he ordered the genocide of thousands of Haitians living in the Dominican Republic. In order to maintain power he also eliminated those individuals who questioned his authority, such as Jesús de Galíndez, who disappeared in New York City in 1956 while working on a dissertation that documented the abuses of the Trujillo regime. The murder of the Mirabal sisters on September 25, 1960, is one more example of the dictator’s brutality. Trujillo’s violent reign as well as his personality quirks (such as wearing numerous military medals and re-naming streets after his family members) make him a frequent character in literature. Both In the Time of the Butterflies and La fiesta del Chivo chronicle Trujillo’s extreme violence as well as his idiosyncrasies. Julia Alvarez’s interest in the Dominican Republic and in the Trujillo dictatorship is intimately connected to her childhood. As a native Dominican, she spent the first decade of her life on Hispaniola before emmigrating with her family to the United States in 1960. Alvarez’s father was involved in an underground political group that held plans to overthrow the dictatorship, and the family was fearful of Trujillo’s retaliation. In Something to Declare, a 1998 collection of personal essays, Alvarez describes her family’s situation just before they left the island. Though a child at the time, she describes her parents’ anxiety as black SIM (Trujillo’s secret police) cars parked outside their home at night, putting their family under virtual house arrest (15). Alvarez first heard of the --- Mirabals several months after leaving the Dominican Republic. Their story made a strong impression on her, but it was not until 1986 that she decided to write about them. In that year she was asked to compose a small paragraph about a Dominican heroine for a women’s press. As she researched the project, Alvarez became drawn to the Mirabal sisters and their story. In the following years, Alvarez continued to investigate the siblings and interviewed many of the people who knew them. Previous to her release of *In the Time of the Butterflies*, Alvarez had published two books of poetry and one novel. That first novel, *How the García Girls Lost Their Accents* (1991), quickly received critical recognition. Like *In the Time of the Butterflies*, *How the García Girls Lost Their Accents* also focuses on female protagonists. The novel depicts a family with four young daughters that leaves the Dominican Republic to escape the Trujillo dictatorship. Their story is told in reverse chronological order, with each of the four sisters sharing her perspective. The novel focuses on the difficulties the girls face as they go through the process of acculturation. Though Alvarez is more concerned with the sisters’ experience in the United States than with Trujillo, the dictator’s effect on the family is obvious. More recently Alvarez has published a number of books of fiction, poetry and essay including *¡Yo!* (1997), a sequel to *How the García Girls Lost Their Accents*, followed by *Something to Declare* (1998), and *In the Name of Salomé* (2000). The later work is also connected to the author’s native country. This historical novel centers on the story of Salomé Ureña who, in 1878, became the first recipient of the National Medal in Poetry in the Dominican Republic. Ureña was a strong advocate of women’s education and encouraged her husband, a political leader and president for one year, to support that cause. Alvarez is known as a witty and creative writer whose books take on important issues related to women and to Latino culture. Mario Vargas Llosa’s attachment to the Dominican Republic is less personal. A native Peruvian, many of the author’s previous novels have focused on his country of birth. Like Alvarez, Vargas Llosa began to write *La fiesta del Chivo* many years before he would finally realize its publication. In an interview, Vargas Llosa has explained that he imagined the novel as early as 1975, while on an eight month visit to the Dominican Republic for the filming of one of his fictional books (see Barnabé 1). Vargas Llosa was so impressed by the lasting effects of dictatorship in that Caribbean nation that he began to formulate ideas for a novel. Over the following years, he researched the Trujillo regime and talked with Dominicans who had lived through the era. Though Vargas Llosa describes his decision to write about the Dominican Republic as “puramente accidental” (qtd in Barnabé 1), the element of social and political critique that the novel contains is by no means new to the author’s oeuvre. Throughout his career, Vargas Llosa has spoken often of the socio-political frustrations which compel him to write: “Literature in general and the novel in particular are expressions of discontent. Their social usefulness lies principally in the fact that they remind people that the world is always wrong, that life should always change” (qtd. in Williams, *Mario Vargas Llosa*, 8). Perhaps Vargas Llosa described his idea about writing best with his well-known statement, “La literatura es fuego,” given when he received the prestigious Premio Rómulo Gallegos in 1967 (Williams, *Mario Vargas Llosa*, 9). For Vargas Llosa, literature is born of frustration and is meant to expose the wrongs in society. Many of Vargas Llosa’s novels, especially his earliest, critique a specifically Peruvian society. His first novel, *La ciudad y los perros* (1963), reflects the time he spent at the Leoncio Prado Military Academy in Lima. Though the young author disliked his experience there, it became a source of material for his writing. In the novel, the military academy functions as a microcosm of Peru. The book was deemed so critical of the academy that the school officials organized the burning of one thousand copies of the book on the school patio (Williams, Mario Vargas Llosa, 13). In another novel set in his native country, Conversación en La Catedral (1969), Vargas Llosa writes about the government of Peruvian dictator Manuel Odría (1948-56). The two protagonists of this lengthy novel, Santiago and Ambrosio, sit in a café called La Catedral and discuss life in Peru, as well as Santiago’s father’s connection to the dictatorship. In 1981, Vargas Llosa published La guerra del fin del mundo, another novel addressing politics, but this time he chose a different setting. La guerra del fin del mundo fictionalizes the actual uprising of a religious community in Canudos, Brazil, and the government’s violent retaliation. These novels in particular have cemented Vargas Llosa’s reputation as a writer concerned with critiquing societal failing. It should be noted, however, that not all of Vargas Llosa’s writing has been political. For example, La tía Julia y el escribidor (1977) is a humoristic novel centered on the author’s marriage to his first wife Julia Urquidi. Vargas Llosa has also published several novels dealing with erotic themes such as Pantaleón y las visitadoras (1973), Elogio de la madrastra (1988), as well as his recent Travesuras de la niña mala (2006). However, the release of La fiesta del Chivo (2000) confirmed the author’s continuing interest in political issues as well as his on-going belief that literature can bring about some measure of change. For example, in a 2006 interview about La fiesta del Chivo, Vargas Llosa stated: Quizá de joven pensaba, por la influencia de Sartre, que la literatura podía introducir cambios más o menos inmediatos y radicales en la vida social. Hoy día ya no soy tan optimista, creo que no ocurre así. Pero no he llegado al pesimismo de quienes creen que la literatura no causa ningún efecto. Pienso que sí tiene unas reverberaciones en la historia, pero creo que son lentas, que uno no puede planificarlas. (qtd in Patriau 4) Although change may not be immediate, Vargas Llosa confirms his early conviction that literature can in fact be a catalyst of socio-political reform. No doubt the recent Nobel Prize recipient’s writing will continue to influence generations. Although Alvarez and Vargas Llosa come from distinct backgrounds and employ different writing styles, they address similar themes in *In the Time of the Butterflies* and *La fiesta del Chivo*. Specifically, both Alvarez and Vargas Llosa examine the situation of women under dictatorship. While the political criticism in these novels is not limited to those involving women, both Alvarez and Vargas Llosa make women’s experience a significant part of their vision of the Trujillato. *In the Time of the Butterflies* and *La fiesta del Chivo* show the psychological effects that abusive governments can have on women. The protagonists in these novels suffer a broad range of abuses at Trujillo’s hand which affects their transition and growth into adulthood. Female development is a key concern of both *In the Time of the Butterflies* and *La fiesta del Chivo*. Women’s development spans a large and expanding body of research. It is not within the aims of this study to review all of the many contributors and ideas in this important field. Instead, I focus on the findings of social psychologist Carol Gilligan. Gilligan’s ideas about female identity formation shed light on the ways Alvarez and Vargas Llosa depict their characters and critique dictatorship. In her influential book *In a Different Voice: Psychological Theory and Women’s Development* (1982), Gilligan writes of the differences between male and female psychology. Since this early publication, she has continued to expand on her ideas in books such as *Making Connections: The Relational Worlds of Adolescent Girls at the Emma Willard School* (1990), co-edited with Nona Lyons and Trudy Hanmer and *Meeting at the Crossroads: Women’s Psychology and Girls’ Development* (1992) co-authored with Lyn Mikel Brown. In *In a Different Voice* Gilligan explains that previous to the time of her writing, many psychologists viewed women’s development as inferior to men’s and saw female differences as defects rather than strengths. The devaluation of female development was rooted in Freud’s theories of identity formation, which center on the Oedipus complex. Freud’s ideas, however, did not describe female experience and therefore, Gilligan writes, “[h]e considered [the] difference in women’s formation to be responsible for what he saw as women’s developmental failure” (7). Gilligan argues that developmental differences often provide women with unique values and should not be seen as weaknesses. She cites Nancy Chodorow’s findings, which also trace distinctions between male and female growth patterns to childhood and adolescent years. Chodorow suggests that girls’ identity is based on attachment and connection while boys’ is founded on separation. For most children the primary caregiver is female, which may partially account for gender difference. Gilligan summarizes: Consequently, relationships, and particularly issues of dependency, are experienced differently by women and men. For boys and men, separation and individuation are critically tied to gender identity since separation from the mother is essential for the development of masculinity. For girls and women, issues of femininity or feminine identity do not depend on the achievement of separation from the mother or on the progress of individuation. (8) Gilligan centers her findings regarding female developmental psychology on the importance of connection and relationships. In issues involving identity, decision making, and morality women consistently demonstrate a high awareness of the needs of others and a desire to preserve and maintain relationships, while traditional male values prioritize separation, autonomy, and impartiality. Gilligan does not write to condemn male values, but suggests that by becoming aware of each other’s strengths, communities can become more balanced. Often developmental moments are accompanied by significant rites of passage in an individual’s life. Although this thesis is primarily concerned with female development, it may be useful to define the phrase *rite of passage* as well. Rites of passage can refer to a large variety of rituals such as initiation ceremonies in ancient and modern cultures, religious rites such as baptism, or secular rituals like high school graduation or civil marriage. The term “rite of passage” was first used by Dutch anthropologist Arnold van Gennep in 1908. Gennep writes of “special acts” that mark an individual’s passing from one phase of life to another: > The life of an individual in any society is a series of passages from one age to another and from one occupation to another. Wherever there are fine distinctions among age or occupational groups, progression from one group to the next is accompanied by special acts, like those which make up apprenticeship in our trades. (3) Gennep explains that all individuals experience changes throughout life in age, roles (occupation), and responsibilities. He remarks that such changes or transitions are “looked on as implicit in the very fact of existence” (3). Alvarez and Vargas Llosa depict several important rites of passage in their character’s lives, such as christening, menstruation, attending boarding school, marriage and sexuality. In *In the Time of the Butterflies* and *La fiesta del Chivo* Alvarez and Vargas Llosa use rites of passage to portray significant developmental moments in the lives of their protagonists. Though the two novels have very different outcomes, both can be better understood through a study of these rites of passage and their impact on the characters’ growth. In Chapter One of this thesis, I examine the relationship between dictatorship and female development in *In the Time of the Butterflies*. In the novel, Alvarez depicts the development of the four Mirabals—Patria, Dedé, Minerva and María Teresa (Mate), historical women who have grown to be legends in the Dominican Republic. With the exception of Dedé, all of the sisters become involved in politics, and form part of the anti-Trujillo movement. On September 25, 1960, Patria, Minerva and Mate were assassinated on their way home from visiting their husbands, who at the time were imprisoned for their own participation in movements that opposed Trujillo. Although the Mirabals are best-known for their brave contributions on the political scene, Alvarez focuses many pages on the growing-up years of the sisters, long before they held any prominence in the Dominican Republic. She writes of their early experiences attending school, making friends, and dating. Alvarez describes important rites of passage in their lives as they mature to adulthood. In many cases, significant rites of passage for the Mirabals occur within female communities or in connection with other women. In Chapter One, I discuss how communities play a role in female identity formation. Because the Mirabals grow in connection with others, they place high priority on the relationships and needs of others in their lives. I show how Alvarez contrasts the Mirabals behavior with that of Trujillo. In *In the Time of the Butterflies*, the Mirabals become courageous women, who exemplify female strengths. Unlike Trujillo, who constantly acts selfishly, the Mirabals are defined by the values they place on relationships and community. In Chapter Two I examine the negative effects of dictatorship on Urania’s growth in *La fiesta del Chivo*. The most significant rite of passage to occur in Urania’s adolescence leaves her severely traumatized and unable to form relationships. Urania’s ‘failure’ to progress is a reflection of the devastating effect the dictatorship often had on women, rather than an indication of personal weakness. When Urania is only fourteen-years old her father offers his daughter’s virginity to Trujillo, hoping to mend his political career. As a result, Urania is filled with anger and rage and loses her ability to connect with others and to form relationships. Throughout the novel she is frequently described as isolated and alone. In this chapter, I analyze how Vargas Llosa uses a dictator’s sexual abuse of a minor as a criticism for the abuse of power during the Trujillo years. It is significant that Urania’s emotional pain arises not only from physical violation but also from her family’s betrayal. Urania’s father, Agustín, represents the machismo of the Trujillo regime. By offering his daughter to Trujillo, he reflects a society that devalues women. In this chapter I also discuss how “poor fathering” becomes a symbol of the Trujillo dictatorship. In addition, I describe the positive changes in Urania’s development that occur as she shares her story with her family after thirty-five years. I show how Urania’s growth in the final stages of the novel may represent Vargas Llosa’s hope for Latin American’s future. A surprising number of similarities exist between the protagonists of *In the Time of the Butterflies* and *La fiesta del Chivo*. All five women, for example, experience first-hand the abusive nature of the Trujillo regime as they grow up amidst dictatorship. Trujillo’s violence, however, impacts Álvarez’s and Vargas Llosa’s characters in different ways. Ideas about the process of female identity formation help explain the characters’ response to dictatorship in both novels. The Mirabal sisters from Álvarez’s account experience growth through their connection with others. Alvarez focuses on the role of relationships and community in the Mirabals’ daily lives. The qualities and strengths that define the Mirabals in the private sphere also give them the courage to stand against Trujillo. In contrast, Urania’s horrific encounter with the dictator has a debilitating effect on her socially and emotionally. Her pain is evidenced by an inability to connect to others and have fulfilling relationships. Vargas Llosa uses Urania’s traumatized growth as a metaphor for the suffering of all Dominicans during Trujillo’s time in power. While female development follows a different course for Urania than it does for the Mirabals, the principles that define the female growth process are the same in both novels. Alvarez describes her characters’ maturation as a process of connecting to others and cultivating community-centered values. Conversely, Urania’s isolation and separation are evidence of her crisis of development. In both novels, the concept of connection elucidates the process of female identity formation and gives insight into Trujillo’s violent reign. CHAPTER ONE: The Process of Becoming Butterflies: Female Development and Community in Julia Alvarez’s *In the Time of the Butterflies* In *In the Time of the Butterflies*, Julia Alvarez focuses on the development of the four Mirabal sisters. Alvarez writes in a postscript to the novel that the Mirabal sisters are “models for women fighting injustices of all kinds” (324). She also expresses her admiration for their bravery: “During that terrifying thirty-one-year regime, any hint of disagreement ultimately resulted in death for the dissenter and often for members of his or her family. Yet the Mirabals had risked their lives” (323). While Alvarez depicts many of the heroic acts of the Mirabals in the political movements that opposed Trujillo, she also dedicates numerous pages to the formative years of their youth, long before they held any prominence in the Dominican Republic. Isabel Zakrjewski Brown sums up Alvarez’s approach in this way: “In the novel, Alvarez invents the adolescence and early adult years of the protagonists. Having gathered very general information on the sisters’ lives through interviews and research, Alvarez then fictionalizes their daily lives [...]” (1). For example, Alvarez includes sections on the Mirabals’ experiences in boarding school, among friends, and with potential suitors, before they became politically involved. In these settings, she focuses on the values they learn as they mature in life. It should be noted that Alvarez’s depiction of the Mirabals has been a source of controversy for some scholars. For example, Lynn Chun Ink discusses the feminist concerns associated with casting the Mirabals in private settings such as the home and school instead of the public arena. Ink suggests that Alvarez’s focus on the daily, familial lives of the Mirabals confines them to the private sphere, instead of centering on their political contributions. Ink writes that Alvarez’s “revision of Community [her attempt to show women’s historical involvement] tends to utilize the very masculinist imperialist discourse it seeks to undermine” (790). Roberto González Echevarría makes a similar critique in his oft-cited New York Times book review: “The sisters appear, on the whole, to be reactive and passive. Their education in religious schools, and their chaste and rather naive development into womanhood, take up too many tedious pages” (1). Like Ink, González Echevarría suggests that Alvarez’s emphasis on the private lives of the Mirabals may distract from the depiction of their political achievements (1). Alvarez, however, defends her version of the Mirabals in her postscript to the novel. She states that she wanted to avoid deifying the Mirabals, although they have become legends in the Dominican Republic (324). In addition, Alvarez’s approach supports a set of values which may be controversial, but that is essential in understanding the novel. In the private settings that Alvarez often chooses for her characters, the Mirabals frequently demonstrate traditionally feminine values such as friendship and relationship building. As the Mirabals grow up amidst dictatorship they learn to value people and individuals and often express their consideration and selfless concern for others. These principles are consistent with other writing by Alvarez. In the book Women Writing Resistance (2003), a collection of short essays, editor Jennifer Browdy de Hernandez includes a brief essay by Alvarez entitled “I Came to Help: Resistance Writ Small.” Alvarez comments on women’s ability to help society by forming connections and relationships. She writes about Camila Ureña, the daughter of the famous Dominican poet Salomé Ureña. Unlike her mother, Camila lived a quiet, non-descript life, teaching Spanish at Vassar for years. To everyone’s surprise, in 1960, Camila left home and went to Cuba to join the literacy brigade. Alvarez comments that change frequently occurs through small actions such as these. She writes, “I trust [in] that connective, consensus- building, hands-on process which I think of as a traditionally female process with its roots in the kitchen, women working together” (212). In this quote, Alvarez also notes that women’s strength often comes in their ability to build and form connection with others. In the same essay, Alvarez cites several examples of groups of women who have made small changes that brought about significant results. Her description of these powerful, female movements sheds light on her characterization of the Mirabals. Alvarez writes, [A] group of women wearing handkerchiefs and black dresses and practical tie shoes circle a plaza in Argentina. A young woman in a threatened forest hugs a tree. Another and another join her. A handful of women in a Greek village refuse to sleep with their husbands until they end a war. A housewife in South France opens the back door and ushers her Jewish neighbors to a cellar of her house. (212) In these examples, Alvarez describes a community aspect to women’s resistance. Likewise, community plays an important part of the Mirabals’ lives in *In the Time of the Butterflies*. As the young Mirabals mature into adulthood they learn and demonstrate positive values within group settings. This phenomenon is consistent with the findings of social psychologist Carol Gilligan regarding the process of women’s development. She explains that the link to others is foundational to female growth. She states, “[W]omen not only define themselves in context of human relationships but also judge others in terms of their ability to care” (17). It is not surprising, then, that there are numerous examples of communities in *In the Time of the Butterflies* and most of them are comprised exclusively of women. The Mirabal sisterhood is one of those female communities. Additional examples of groups of women in Alvarez’s novel include the all-girls school the sisters attend, the female section of the prison to which Minerva and Mate are confined for a period of seven months, the religious retreat Patria attends, and Enrique Mirabal’s second family, which is comprised of four daughters. Considering Alvarez’s comments on women’s resistance, her approach to the Mirabal’s lives is more clear. Alvarez focuses on their developmental years, years spent in community settings where they learn the importance of caring for others and building relationships. Throughout the novel, relationships shape who the Mirabals become. Through the influence of the networks of friends established by the young Mirabals, they transform into strong women and form a legendary part of the anti-Trujillo movement. These women, as described by Alvarez, are heroines not only because of their political involvement but also because of their values of friendship and care. As part of her focus on development, Alvarez creates a series of pivotal moments, or rites of passage, in the Mirabal sisters’ lives that shape their identity as they mature into womanhood. Alvarez’s emphasis on the transformative experiences of her characters is evident from the title of her novel. While butterflies refer to the code names of the Mirabals in their underground political activities, the transformation of a caterpillar to a butterfly is also a powerful symbol of growth.4 --- 3 It is noteworthy that societies of women such as the Mirabal characters are frequently found in literature. Nina Auerbach explains that societies of women have played a significant role in literary history. She mentions in particular Jane Austen’s *Pride and Prejudice* (1813) and Louisa May Alcott’s *Little Women* (1868, 1869). Like *In the Time of the Butterflies*, these novels both contain literary sisterhoods (the Bennets and the Marches, respectively), which exemplify the value of female societies. 4 On a basic level the change from a caterpillar to butterfly can be seen as a symbol of transformation. In addition, it is significant that some cultures have noted the powerful imagery associated with butterflies and have involved them in traditional ceremonies. For example, Bruce Lincoln describes how this symbol plays a role in the female initiatory rites of the Tukuna people of Northwest Brazil. Part of the ceremonies included the seclusion of the young initiand in a chamber for three days. Lincoln comments that “[t]he seclusion chamber is, in truth, something of a retort of crucible, in which a dramatic transformation is effected” (54). A song is sung before the girl emerges that associates her with a caterpillar in Alvarez’s focus is on her characters’ development, she naturally begins her story at an early period in their lives. *In the Time of the Butterflies* commences in 1938, when the Mirabals—Mate, Minerva, Dedé, and Patria—range in age from three to fourteen years old. Alvarez recreates the process through which each of the girls matures. For example, one early experience of growth occurs in chapter two, which contains a coming-of-age experience for Minerva and lays the foundation for her future political involvement. As the chapter begins, Minerva is twelve years old. She and her two older sisters have convinced their father to allow them to attend an all-girls boarding school called *La Inmaculada Concepción*. Some of the significant events of this chapter include Minerva making friends with another girl named Sinita, Minerva’s first menstruation, the story of Lina Lovatón, and Minerva’s discovery of Trujillo’s corruption. Through these experiences, Minerva loses her previous childhood naiveté regarding the Trujillo regime and develops a more realistic understanding of the dictatorship. Alvarez creatively entitles the first section of the chapter “complications,” a term which takes on multiple meanings. First, it refers to the onset of menses, an important rite of passage. In many cultures menarche signals that a young woman is ready to be initiated into society. Alvarez’s inclusion of this detail signals that Minerva is at a developmental threshold. Alvarez parallels Minerva’s knowledge of Trujillo’s corruption with her first menstruation. This pairing of major events symbolizes how trying life might be for a young girl growing up during the *Trujillato* and holds an implicit critique of the dictatorship. The night Minerva begins bleeding a chrysalis. Lincoln writes, “The chamber is thus compared to a cocoon into which the girl went as a caterpillar, immature, plain, and terrestrial, and from which she emerges a butterfly, mature, beautiful, and celestial” (55). Although Alvarez is most likely not referencing the initiation rites of the Tukuna with her title, it is noteworthy that the caterpillar/butterfly metaphor can be used to describe female growth and transformation. also happens to be the night her new friend Sinita shares how her brother and uncles were murdered by Trujillo. In addition, Sinita describes Trujillo’s crooked path to the presidency. For Minerva, who like other children grew up sheltered about Trujillo’s true nature, the news is disheartening. She describes her shock as a total blow to her belief system: “It was as if I had just heard Jesus had slapped a baby or Our Blessed Mother had not conceived him the immaculate conception way. ‘That can’t be true,’ I said, but in my heart, I felt a china-crack of doubt” (17). After Sinita and Minerva’s late-night conversation about Trujillo, Minerva falls asleep with abdominal pains and wakes up with the realization that her “complications” have started. In many ways, her life becomes more “complicated” now that she recognizes Trujillo’s corruption. During this time she develops an interest in politics, an interest that will later cost her life. Minerva also comes to realize that life for a young woman could be especially difficult under the dictatorship. Minerva becomes aware not only of Trujillo’s political corruption, but also of his mistreatment of women. Later in chapter two, the story of Lina Lovatón, a beautiful, fellow-student, provides further evidence of Trujillo’s true nature to Minerva. In the novel, Lina, a schoolmate of Minerva, unintentionally attracts Trujillo’s attention. Though Trujillo is married and thirty-five years older than the seventeen year-old Lina, he seduces her. On a trip to visit Trujillo, Lina becomes pregnant and as a result drops out of school. As Minerva witnesses this event, she gains new understanding of the situation of women under Trujillo’s government. After Lina’s experience, Minerva starts to bind her chest, hoping to stall her physical development and escape Lina’s fate. At this time, Minerva also begins to feel an intense desire to put an end to the Trujillo Dictatorship. Minerva’s new-found awareness of Trujillo’s corruption coupled with her physiological change bring about an initiatory experience in her life. Douglas J. Weatherford points out that new knowledge or perspective is often a key element of a person’s coming-of-age. He writes, “Initiation [. . .] is the process by which a liminal protagonist takes on a new metaphysical and/or social identity with its corresponding changes in knowledge, world vision, social status, and gender roles” (11). Minerva notes that all of her experiences lead to a deepened understanding of life, particularly in the Dominican Republic: And that’s how I got free. I don’t mean just going to sleepaway school on a train with a trunkful of new things. I mean in my head after I got to Inmaculada and met Sinita and saw what happened to Lina and realized that I’d just left a small cage to go into a bigger one, the size of our whole country. (13) Minerva mentions the freedom that comes from knowledge, yet at the same time the lessons learned are far from positive. In her case, entering the adult world means learning about the corruption of the regime, something she had not understood before. This lesson will define her life’s work of fighting that evil. The location as well as the lessons Minerva learns in chapter two are significant to the novel. First, Minerva experiences this crucial time in her physical and psychological development at an all-girls boarding school, or in a community of women. This location symbolizes the importance of relationships in the process of female maturation. Minerva’s revolutionary tendencies are also fostered by her connection to Sinita as well as to Lina. Both have been wronged by Trujillo, and Minerva desires justice for her friends, particularly for Sinita. In addition to learning about politics from Sinita, Minerva gains a deeper understanding of friendship as she connects with Sinita across socio-economic boundaries. Sinita is ostracized at school because of her shabby clothes and apparent poverty, and Minerva is one of the only students who will talk with and befriend her. When Sinita tells her story, Minerva begins to see Sinita in a different way: “She told me stuff I didn’t know about her. I thought she was always poor, but it turned out her family used to be rich and important. Three of her uncles were even friends of Trujillo. But they turned against him when he began to do bad things” (17). Minerva learns that things, especially under the dictatorship, are not always as they appear. She discovers that the revered Trujillo of her childhood is nothing more than a façade and that looks can be deceiving. In the shabby and apparently-rude Sinita, Minerva gains a close friend. Minerva’s knowledge and friendship also come with a greater level of responsibility. The nuns at the school quickly notice the two girls’ friendship and ask Minerva to look after Sinita. Minerva accepts the responsibility, not realizing that she will have to protect Sinita later from the dangers of the regime. Alvarez describes Minerva’s first year at school at a formative time and it is not coincidental that her growth occurs as a result of friendship and relationships. Through these experiences Minerva gains her interest in politics, an interest that will shape the rest of her life. Another important rite of passage in In the Time of the Butterflies involves the more restrained sister, Patria. While Patria’s most obvious rite of passage involves marrying Pedro González (she meets him when he visits the all-girls boarding school) another influential time for her is when she decides to join the anti-Trujillo movement. Throughout the novel, Patria is known for being a dedicated wife and mother and staying out of trouble. However, things change when she attends a religious retreat in the mountains of the Cibao region in June of 1959. While on the retreat, there is a surprise invasion by a rebel group in the same area. A series of explosions rocks the building where Patria and the other women are listening to a sermon. The invasion is quickly stopped by Trujillo’s forces but has a significant effect on the country. In fact, the Mirabals later form an underground movement which they name *El 14 de junio*, to commemorate the day of the failed attempt. During the explosions, Patria witnesses a traumatic event when she looks out the window and sees a young rebel boy gunned down. She relates to this boy as if he were her own son and the terrible scene has a profound impact on her. Afterwards she whole-heartedly participates with her sisters in their revolutionary activities. Although witnessing a traumatic event may not seem like a rite of passage, Patria’s experience proves to have a transformative effect on her. She says, “Coming down the mountain, I was a changed woman” (162). When Patria returns, her family members are all waiting for her, fearing she may have died in the explosions. Symbolically, her experience represents a kind of death and rebirth. Mircea Eliade writes: “Every ritual repetition of the cosmogony is preceded by a symbolic retrogression to Chaos. In order to be created new, the old world must first be annihilated” (xiii). Eliade goes on to explain that in initiatory rites, for example, a child must symbolically die to childhood in order to be reborn or resurrected to adulthood (xiii). Likewise, during Patria’s experience, she is figuratively reborn as a revolutionary. She describes how previous to the retreat, she “wouldn’t have hurt a butterfly,” but now is “shouting, ‘Amen to the revolution’” (164). Álvarez also describes Patria’s transformation as an important rite by using religious symbolism. It is significant that Patria’s experience occurs in the mountains, or on higher ground, during a religious retreat. Her story is not unlike Moses’, who also received his calling on a mountain after a sacred experience. But while Moses’ experience fits the model of separation for male development, Patria’s transformation takes place among a community of women, and as a result of another person’s (the young boy’s) suffering. In Patria’s story, Álvarez again links the --- 5 This is the same revolutionary movement to which Álvarez’s own father belonged before her family emigrated to the United States in 1960 (Álvarez, *Something to Declare* 198). Mirabals’ growth to community and relationships. Patria will ultimately sacrifice her life because of the connection she felt to the young boy she witnessed dying. Mate’s journal accounts of her imprisonment in chapter eleven also describe a powerful rite of passage and are some of the most stirring and emotional moments in the novel. Through Mate, Alvarez shows that, for women, community-focused thinking not only benefits society, but also forms a basis for a sense of selfhood in women’s development. Describing the importance of Mate’s prison account, Silvio Sirias writes, “It is through Mate’s prison diary that Alvarez most closely explores women’s issues. Mate proves to be the most enlightened, yet compassionate, feminist among the Mirabal sisters” (66). All of the chapters told from Mate’s point of view are journal accounts. Her earliest entries begin when she is in grade school and include descriptions of clothes, school, boys, and family life. While Mate’s early writing is endearing and sometimes even comical, she does not demonstrate the depth and reflection that is apparent in some of her sisters’ chapters. Sensing Mate’s superficial nature, Minerva buys her sister a journal because contemplation and writing “deepen one’s soul” (30). Still Mate remains aloof to her sister’s revolutionary activities until she meets Leandro, whom she later marries. Leandro is a member of the same underground organization as Minerva and her husband Manolo. When Mate learns of Leandro’s involvement, she too asks to join Minerva. Drawn initially to the underground through love rather than revolution, Mate confesses that she is not as strong as her older sister: “I admit that for me love goes deeper than the struggle [. . . ]. I would never be able to give up Leandro to some higher ideal the way I feel Minerva and Manolo would each other if they had to make the supreme sacrifice” (147). By developing Mate’s character as an ‘ordinary’ young woman with no particular interest in politics, Alvarez emphasizes Mate’s growth in prison. Early in chapter eleven Mate gains an increased appreciation for others. She and Minerva are held in a prison called La Cuarenta with a group of female political prisoners (revolutionaries like the Mirabals). To Mate’s dismay, she and the other women held for political reasons share a small room with sixteen other female inmates who were convicted on more serious crimes. Mate initially describes those women with disdain: “‘Nonpoliticals,’ all right. Prostitutes, thieves, murderers—and that’s just the ones who have confided in us” (228). Initially Mate is judgmental towards the other women, but when they act charitably towards her, she changes her perspective: “[I]t raised my spirits so much, the generosity of these girls I once thought were below me” (230). As her friendship with certain inmates solidifies, she reflects, “There is something deeper. Sometimes I really feel it in here, especially late at night, a current going among us, like an invisible needle stitching us together into the glorious, free nation we are becoming” (239). Curiously it is in this communal environment that Mate is able to develop her own unique voice and perspective. At one point during the sisters’ seven-month stay, Mate is chosen to be interviewed by the Organization of American States, which was concerned about how the prisoners were being treated. The women know the interview room will be bugged by Trujillo’s secret police (the SIM), so Mate will be limited in what she can say. Minerva and another prisoner write a statement regarding their mistreatment in prison, which they hide in Mate’s hair for her to let drop during the interview. Minerva also asks Mate to write an additional personal statement about a traumatic experience she had while in prison when she was tortured by the SIM for information. Mate is hesitant to write the later statement because, though anonymous, word could get back that someone in the women’s quarters complained and an innocent guard that she befriended (Santicló) may be punished by the SIM. Minerva argues with Mate about the necessity of the second testimony. Mate describes her conversation with Minerva in her diary: Ay, Mate, promise me, [Minerva] says, looking in my eyes, please promise me. So I say to her the only things I can say. I promise you this, I’ll be true to what I think is right. Minerva has never heard such talk from me. Fair enough, she says, fair enough. (251) Mate goes to the interview with both statements hidden in her hair, but in the end she only lets Minerva’s fall and not her own. In this circumstance, Mate follows her own moral values, independent of what Minerva thinks she should do. Mate’s reasons reflect a deep awareness for her friendships and relationships. By releasing only Minerva’s statement, she is able to help the political prisoners as well as shield the guard who has been kind to her. Mate’s ability to stand up for her ideals to protect her friends exemplifies her growth. Gilligan explains that women’s focus on relationships carries into adulthood. She writes, “When women construct the adult domain, the world of relationships emerges and becomes the focus of attention and concern” (167). Mate’s conflict between pleasing Minerva or protecting her friends suggests a tension women often face because of the priority they place on relationships. While being other-focused can be seen as a strength, women also run the risk of stifling their desires to keep peace or to build relationships. Carol Gilligan and Lyn Mikel Brown write, “Women [ . . . ] tended to speak of themselves as living in connection with others and yet described a relational crisis: a giving up of voice, an abandonment of self, for the sake of becoming a good woman and having relationships” (Meeting at the Crossroads 2). Voice and silence become key terms in Gilligan’s research. She describes voice in the following way: “Voice is central to our [women’s] way of working—our channel of connection, a pathway that brings the inner psychic world of feelings and thoughts out into the open air of relationships where it can be heard by oneself and by other people” (20). Voice is the ability to be true to one’s thoughts and feelings and to express them when needed. Voice represents a kind of authenticity in action and relationships. Mate’s decision in prison is an excellent example because she acts in a way that is true to her inner moral compass, instead of sacrificing her values to keep peace with Minerva. In *In the Time of the Butterflies*, Patria, Minerva and Mate become strong women of voice, but Dedé’s situation is more complicated. Through the character of Dedé, Alvarez acknowledges that relationship-focused development can be dangerous. Throughout the novel, Dedé is an example of a woman who constantly gives up her desires and values to keep peace in a patriarchal society and household. Because her husband, Jaime, forbids Dedé from becoming involved in politics, she is the only sister who does not join the anti-Trujillo movement. But, long before Jaimito refuses to allow Dedé to participate, she begins to compromise her beliefs to appease others. This tendency is seen clearly when the young Mirabals hatch a plan to attend boarding school. Although Dedé wants to leave with her sisters, she invokes her self-sacrificing nature and offers to remain at home to help her father with the store. Dedé places others above herself and is willing to sacrifice much—even an opportunity at adventure and education—to appease others. Alvarez both praises and chastises Dedé’s desire to meet the needs of those around her. While Dedé often nobly aids the people in her life, sometimes she does so to her own detriment and against her better judgment. In such cases, she silences her own instincts and enables others to take advantage of her. Sadly, Dedé compromises her own desires when she agrees to marry her cousin Jaimito, in spite of her inner misgivings about him and the negative way he treats her. Alvarez describes Jaimito’s character as difficult and he is often unwilling to listen to her. In one particular scene Jaimito tries to convince Dedé that her friend Lío’s political involvement is too radical and that it is hurting the country. Dedé believes that Lío can make a difference, but Jaimito suggests that he should compromise more of his beliefs and standards. In their conversation, Alvarez introduces the idea of compromise and shows how Dedé is unable to stand up to her cousin and express her thoughts. Jaimito tried convincing Dedé to his way of thinking. “Don’t you see, my heart, all life involves compromise. You have to compromise with your sister, your mother has to compromise with your father, the sea and the land have to compromise about the shoreline, and it varies from time to time. Don’t you see, my life?” “I see,” Dedé said at last, already beginning to compromise with the man she was set to marry. (79) In this scene, Dedé agrees with Jaimito, but obviously there is tension. She pauses before she answers him, suggesting that she has a difference of opinion, and yet she does not share it. Although there are problems in their communication, Dedé overlooks these when she agrees to marry Jaimito. In addition, Alvarez describes Jaimito as the man Dedé is “set” to marry, suggesting that Dedé does not recognize her choice in the matter. Indeed, Dedé further compromises her feelings and desires when she (hesitantly) accepts Jaimito’s proposal of marriage. Both her parents and her cousin’s parents had always assumed the two would marry. Jaimito also puts pressure on Dedé. However she is unsure of her feelings. Her thoughts reflect her uncertainty: “They had been headed for it since they had patted mud balls together as toddlers in the backyard. Everyone said so. There was no question—was there?—but that they would spend the rest of their lives together” (82). Instead of considering her own wishes, Dedé focuses on how family members had planned their marriage for years and on Jaime’s feelings for her. Unfortunately it does not seem to bother Jaimito that Dedé is hesitant. Likewise, throughout their marriage, he continually ignores Dedé’s counsel, wishes, and feelings, often to his own detriment. In several cases, he loses money because he refuses to take his wife’s advice even though she is a talented businesswoman. Over time in her marriage, Dedé constantly silences herself to keep peace, but her sisters notice that she is struggling and unhappy. This is especially true in regard to her sisters’ revolutionary activities. Although Dedé would like to participate, Jaimito adamantly refuses. Alvarez emphasizes this point when Dedé’s sisters approach her about keeping some contraband hidden on their land: What could Dedé say? She had to talk to Jaimito first. Patria had given her a disappointed look, and Dedé had gotten defensive. “What? I should go over Jaimito’s head? It’s only fair. He’s the one farming the land, he’s responsible for this place.” “But can’t you decide on your own, then tell him?” Dedé stared at her sister, disbelieving. “That’s what I did,” Patria went on. “I joined, and then I talked Pedrito into joining me.” “Well, I don’t have that kind of marriage,” Dedé said. She smiled to take the huffiness out of her statement. “What kind of marriage do you have?” Patria looked at her with that sweetness on her face that could always penetrate Dedé’s smiles. Dedé looked away. “It’s just that you don’t seem yourself,” Patria continued, reaching for Dedé hand. “You seem so—I don’t know—withdrawn. Is something wrong?” (176) Patria notices Dedé has been stifling herself and is concerned that her sister is becoming more reserved. When Dedé does try to talk to Jaimito about the land, he refuses her request. Dedé plans to leave Jaimito, but a family crisis pulls them together for a time. Though Dedé recognizes Jaimito’s controlling nature, she also takes some responsibility for their marital struggles: “It was natural to blame herself. Maybe she hadn’t loved him enough” (181). Dedé recognizes that by accepting Jaimito and burying her own voice, she entered a marriage that resulted in unhappiness. In this way Alvarez shows the dangers of women silencing their inner beliefs and feelings in order to appease others. In addition to plot, Alvarez also uses narrative structure to show Dedé’s loss of voice. The novel contains three sections, each divided into one chapter dedicated to each sister, making a total of twelve chapters. Alvarez allows three of the four sisters to tell their stories using the first person. For example, Patria’s chapters are told in her own voice in an almost testimonial style: “From the beginning, I felt it, snug in my heart, the pearl of great price. No one had to tell me to believe in God or to love everything that lives. I did it automatically [. . .]” (44). Minerva’s chapters are similar in structure and style to Patria’s: “All I knew was I was not falling in love, no matter how deserving I thought Lío was. So what? I’d argue with myself. What’s more important, romance or revolution? But a little voice kept saying, Both, both, I want both” (86). The chapters dedicated to Mate’s perspective are the entries that the youngest Mirabal writes in her diary, and are also related in the first person. For example, on the day of her first communion Mate writes, “Minerva says keeping a diary is also a way to reflect and reflection deepens one’s soul. It sounds so serious. I suppose now that I’ve got one I’m responsible for, I have to expect some changes” (30). Unlike her sisters, Dedé’s perspective is given through an omniscient third-person narrator: “Dedé was scared, and angry at herself for being so. She was growing more and more confused about what she wanted. And uncertainty was not something Dedé could live with easily” (77). The use of the third-person with Dedé suggests that she is not in possession of her own voice. While Dedé’s sisters are more free to make their own decisions and express their thoughts, Dedé is more conflicted. Alvarez uses this narrative structure to emphasize Dedé’s inability to truly find expression. While Dedé often chooses not to stand up for her feelings and desires, her silence also exemplifies the difficulties placed upon women in a strong patriarchal society. Trujillo’s treatment of women was particularly cruel and misogynistic. Surprisingly, however, his character appears infrequently in the novel. Instead Alvarez uses examples of other characters to represent the dictator and to demonstrate the difficulties women faced during his time. Writing of Alvarez, Ignacio López-Calvo comments, “Indeed, her censure of patriarchalism of husbands and fathers runs parallel to the condemnation of Trujillo’s despotism. The abusive and immoral middle- or upper-class man metaphorically represents an embryonic state of a potentially more dangerous development: the dictator” (95). Jaimito is one example that Alvarez uses in the lives of the Mirabals to depict Trujillo’s character. Indeed, Dedé’s silence involving Jaimito becomes representative of the national silence that defined the island country due to the oppressive nature of dictatorship. In chapter six, told by Minerva, Alvarez uses the metaphor of thunderous rain to describe how Trujillo was able to silence the Dominican people. As the family travels back from the capital where Enrique was illegally held by Trujillo for petty, personal reasons, it begins to pour. Minerva describes the rain in the following manner: It is raining here, too, [ . . . ]. North to Tamboril and the mountain road to Puerto Plata, the rain drives on, in every *bohío* and small *conuco*, and on out to the Atlantic where it is lost in the waves that rock the bones of martyrs in the deepest sleep.⁶ We’ve traveled almost the full length of the island and can report that every corner of it is wet, every river overflows its bank, every rain barrel to the brim, every wall washed clean of writing no one knows how to read anyway. (116-17) Trujillo’s presence fills the country, and the effect is silence. At a brief rest stop Minerva says, “We sit *silently*, listening to the rain on the thatched roof, a numb, damp, fatalistic feeling among us. Something has started none of us can stop” (116; my emphasis). Even Minerva, the most outspoken Mirabal, is overcome by the rain in this section. The downpour represents the oppressive and overpowering nature of the Trujillo dictatorship on the Dominican Republic. Dedé’s relationship with Jaimito is also reflective of the national situation. Like Trujillo, Jaimito is intolerant of differences of opinion. Dedé’s relationship with Jaimito represents the oppression that results when people are not allowed freedom of expression. Fortunately for Dedé, silence is not the end of her story. Dedé realizes that, as the sister who survived, her life has value. In fact, in the epilogue, there is evidence that Dedé is finally able to recover her voice. The epilogue is dated 1994 and is told from Dedé’s perspective. It begins with --- ⁶ Trujillo was known for casting dissidents out to sea for the sharks to eat. This reference may allude to that practice and shows that Trujillo’s cruelty extended—symbolically and literally—beyond the shoreline of the country. a description of what happened after the sisters’ death. For the first time in the novel, Alvarez uses the first-person pronoun with Dedé’s character: Later they [people saddened over the sisters’ death] would come by the house in Ojo de Agua and insist on seeing me. [. . . ] Each visitor would break my heart all over again, but I would sit on this very rocker and listen for as long as they had something to say. It was the least I could do, being the one saved. (301) Ironically, Dedé finds her voice as she voluntarily chooses to give to others. In her relationship with Jaime, she had to stifle her own desires and reservations to give, but now she chooses to sacrifice, because she believes in the cause. Dedé’s most significant developmental moment seems to be after her sisters’ death when she begins to help the Dominican people by carrying on the martyred sisters’ legacy. In the epilogue, Dedé describes a scene in which her friend Olga tries to convince her to leave her home and the memories of her sisters and to live for herself. Dedé refuses, explaining, ‘After the fighting was over and we were a broken people’—she shakes her head sadly at this portrait of our recent times—‘that’s when I opened my doors, and instead of listening, I starting talking. We had lost hope, and we needed a story to understand what had happened to us.’ (313) Just like Minerva’s growth through Sinita at the Inmaculada, Patria’s transformation on the mountain and Mate’s development in prison, Dedé grows to find her voice by helping the community in meaningful ways. She recognizes that she is needed and, by responding to the needs of others, she finds herself. In this sense, the novel comes full circle. In the end, all four of the Mirabal sisters become strong women who exemplify important female values and perform meaningful service for their nation. Although Trujillo appears infrequently in the novel, Alvarez contrasts his personality with the Mirabals’ strengths. Some of the events that shape Trujillo’s character in the novel are his sexual advances towards Minerva, his unjust holding of Enrqiue Mirabal when Minerva refuses him, his relationship with Lina Lovatón and his refusal to allow Minerva to practice law after she graduates from law school. Writing about Trujillo’s character in *In the Time of the Butterflies*, López-Calvo comments, “Trujillo’s pathological thirst for revenge and adulation is an aspect of his personality that reveals his cruel, and, perhaps, immature nature [. . .].” (91). In addition, Alvarez describes Jaimito’s *machismo* to emphasize characteristics of the regime. In all cases, Alvarez decries Trujillo’s petty and selfish leadership and suggests that the values of the Mirabals are, unfortunately, absent in his character. *In The Time of the Butterflies* gives a unique perspective on women and their impact on society. Alvarez’s interpretation of the Mirabal sisters focuses on the private lives of the Mirabals and the transformative experiences that shape them on the path to adulthood. In many ways, *In the Time of the Butterflies* is about change and transformation. Silvio Sirias comments, *In The Time of the Butterflies* lends itself perfectly to a liminal reading. The Mirabal sisters, the government of the Dominican Republic, the Church, as well as the narrative are, for the greater part of the novel, suspended in a liminal state—betwixt and between what they were and what they are to become. (82) For the Mirabals, connection with others is the catalyst of their development during the liminal moments of their lives. Many of the important events for the siblings occur within the context of community. The Mirabal sisters come to embody values traditionally associated with women, such as a selfless concern for others. Alvarez’s description of the Mirabals’ formative years focuses on a few particular values that can make a difference in society. Julia Alvarez’s *In the Time of the Butterflies* is not only the story of the famous *Mariposas* but of the characteristics that shaped them into strong women who impacted a nation. CHAPTER TWO: “A mí, papá y Su Excelencia me volvieron un desierto”: Poor Fathering and Female Development in Mario Vargas Llosa’s *La fiesta del Chivo* Like Julia Alvarez, Mario Vargas Llosa writes about the Trujillo dictatorship from a female point of view in *La fiesta del Chivo*. While there are three storylines contained in the novel, the central one develops around the fictional character of Urania Cabral. Like the Mirabals, Vargas Llosa’s character grew up in the Dominican Republic during the Trujillo years. The story of Urania’s development into adulthood, however, differs greatly from the pattern the Mirabals follow in Alvarez’s novel. While the Mirabal sisters experience growth through relationships with others, and generally become model women, Urania is frequently associated with solitude and isolation. As the novel begins, Urania is forty-nine years old and has no family of her own. She describes herself as a workaholic and has little spare time for others. Though Urania is portrayed as social and friendly in her childhood, her development was halted painfully by a traumatic experience at the age of fourteen, when her father offers her virginity to Trujillo hoping to mend his political career. After this horrendous experience, Urania shuts herself off from others, including her extended family, --- 7 *La fiesta del Chivo*’s three storylines are developed in alternating chapters. The book begins with Urania’s story, related in the present (the late 1990s), with frequent references to the past. The second storyline is told from the perspective of Trujillo in 1961 on the day of his assassination. Vargas Llosa conveys the Generalissimo’s morning schedule, the meetings he has, his thoughts and reflections—including his frustration with his aging body—all leading up to his death. The third plot tells the story of Trujillo’s assassins as they wait concealed on the side of the road for his car. While in hiding, they each reflect on their reasons for being there, often remembering the injustices they have suffered at Trujillo’s hands. At last the dictator appears and they assassinate him. With Trujillo gone, the accomplices’ plan to set up an interim government seems to be working. However, to their detriment, Trujillo’s secret police (SIM) remains intact, and a bloody power-struggle erupts. Vargas Llosa proceeds by describing the chaotic aftermath of the death of Trujillo as the SIM seeks for his murderers, while continuing to tell Urania’s story of development. 8 Urania states that she works obsessively. She tells her father that her only hobby is to study the Trujillo years and her cousins that her life consists of “[t]rabajar, trabajar, trabajar hasta caer rendida” (564). potential new friends, and lovers. She becomes cold and distant, and though she finds professional success, her personal life is full of emptiness and unhappiness. Not only does Vargas Llosa describe Urania’s crisis of development, he also critiques those individuals who brought about her trauma. Sadly, the perpetrators of Urania’s tragedy are the two primary figures of authority in her life—her father (she is raised without a mother) and Trujillo (who ruled the country in an intensely personal style for over thirty years). Vargas Llosa shows that the Dominican Republic of Urania’s youth was not a safe place for a young woman to mature. This is evident in how Urania’s father and Trujillo betray her trust, even though it is their responsibility to protect her. Ultimately their actions lead to the developmental and psychological consequences she suffers later in her life. The inclusion of abusive authority figures is not new to Vargas Llosa’s work. Raymond L. Williams points out that, in La fiesta del Chivo, Vargas Llosa returns to several familiar demons from his past novels. Williams writes, “El demonio más conocido es el de las figuras autoritarias que han ido apareciendo en su obra como figuras paternas, como figuras militares y como figuras dictatoriales. En esta novela, las tres figuras son sintetizadas en un solo personaje: Trujillo” (Mario Vargas Llosa: Otra historia 272). While Williams only mentions Trujillo, Urania’s father should be considered a significant authority figure as well. Indeed, Urania recognizes the roles of both individuals when she explains to her cousins, “A mí, papá y su Excelencia me volvieron un desierto” --- 9 Several notable novels by Vargas Llosa that contain authority figures include La casa verde (1966), a novel that critiques corrupt political officials for their abuse of the workers in a brothel, and Conversación en la Catedral (1969), a novel dealing with the Peruvian dictatorship of Manuel A. Odría. Other novels depict the negative use of authority by governments. For example, La ciudad y los perros (1962) chronicles the difficulties students face in a strict military academy in Peru. Meanwhile, La guerra del fin del mundo (1981) depicts the bloody turn-of-the-century clash between the government and a religious group in Canudos, Brazil. The war ended in 1897, when the Brazilian authorities sent a large army to squash the uprising. In *La fiesta del Chivo*, not only are those responsible for Urania’s crisis of development persons of authority, they also happen to be paternal figures in her life. Throughout the novel, Vargas Llosa develops much of his criticism of the Trujillo regime around the theme of poor fathering. Urania’s dysfunctional paternal relationships become a metaphor for the Trujillo dictatorship and the psychological effects of abusive authority. This chapter examines Urania’s rape, the implications it has on her development, and how Urania’s character connects to Vargas Llosa’s portrayal of the evils of dictatorship. Just as in Alvarez’s *In the Time of the Butterflies*, rites of passage also play a role in the description of female development in *La fiesta del Chivo*. In *In the Time of the Butterflies*, rites of passage signify moments of growth in the protagonists’ lives. In *La fiesta del Chivo* Vargas Llosa describes Urania’s rape, though brutal and destructive, as an initiatory experience. This violation completely changes her personality and shapes the way she sees the world. At the time of her rape, Urania is characterized as a liminal protagonist, no longer a child, but not quite an adult either. Vargas Llosa also draws attention to this fact: Describing Urania (and her cousin who is of the same age) the narrator comments, “Habían dejado de ser niñas pero no eran todavía señoritas” (375). Unfortunately at this important moment in Urania’s development, violence and force become the defining factors of her life. The fact that Urania’s life is shaped in many ways by rape is a critique of the society in which she lives. Bruce Lincoln comments that initiation by rape is “a pattern followed in a number of male-centered, misogynistically inclined cultures [. . .]” (78). That --- This element may in part be autobiographical as Vargas Llosa has often discussed his own strained relationship with his father. In an interview with Gustavo Faverón Patriau, for example, Vargas Llosa comments, “Como la relación con mi padre fue tan traumática y me ha marcado tanto, a mí no me extraña que se reproduzca de manera constante, con Urania, con Zavalita . . .” (5). Urania’s loss of innocence occurs through abuse is a stark criticism of the Trujillo regime and a commentary about the status of women during his reign. Urania’s rape marks a developmental crossroad in her life, dramatically transforming her personality. Mircea Eliade describes how rites of passage signal a change as great as the death and rebirth of an individual (xiii). An initiate’s former mode of being symbolically comes to an end as a new self is born. Similarly, Urania undergoes a loss (or the death) of her childhood innocence and nature. Through the experience, she also gains new knowledge as she comes to realize the abusive and deceptive nature of the regime. In addition, Urania also comes to see Trujillo’s weakness. Trujillo created an image of himself as invincible and all-powerful and yet, due to failing health he is unable to complete the sex act. The rape scene, though vulgar and explicit, is essential to the novel because it unmasksthe dictator’s physical weakness and impotence. Williams comments, “Así, uno de los cráteres más destacables de la novela es al final, cuando la joven Urania, de catorce años, es llevada a una finca de descanso para un encuentro erótico con el viejo Trujillo de setenta años de edad y sin capacidad sexual” (Otra historia 269). The unveiling of Trujillo’s perversion and corruption brings about Urania’s loss of innocence as well as her acquisition of knowledge. In addition to her disgust over Trujillo’s character, she also learns that he is not all powerful, which Vargas Llosa symbolizes through the dictator’s impotence. In addition, Urania is shocked to discover her father’s level of loyalty to a corrupt regime. Her father’s betrayal further accounts for Urania’s disillusionment. This trauma, tragically, becomes Urania’s coming-of-age experience. Urania’s rape shapes her life and has serious implications for how she will progress into womanhood. At this point, development becomes an important theme in La fiesta del Chivo. Vargas Llosa shows the lingering psychological effects that Urania experiences for years after her trauma. For example, following the rape, Urania shuts herself off from others and is unable to form or maintain relationships. Relational skills are a sign of female growth and are necessary for progression. Carol Gilligan explains, “By changing the [male] lens of developmental observation from individual achievement to relationships of care, women depict ongoing attachment as the path that leads to maturity” (170). Gilligan suggests that connection to others is necessary for women to develop a sense of self and identity: “Intimacy [or connection] goes along with identity, as the female comes to know herself as she is known, through her relationships with others” (12). Vargas Llosa understands the importance of relationships in female development and thus describes the issues in Urania’s life as a problem of connection. He frequently emphasizes Urania’s isolation. Symbolically, the first sentence in chapter one is simply “Urania” (11). This one-word sentence is an early sign of the protagonist’s separation. The meaning of Urania’s name is also significant. Sabine Köllman comments, “[T]he name Urania has special connotations: it refers to Uranus, the coldest planet, a possible symbol of Urania’s emotional situation” (291). Thus from the first word/sentence in the novel, Vargas Llosa alludes to a key weakness in Urania’s development. Urania’s isolation begins in the weeks following her rape. After her encounter with Trujillo, she flees to her school where her teachers hide her and procure a scholarship for her to study in the United States. Over the next few years, Urania successfully earns a Bachelor’s degree and studies law at Harvard University. Afterwards Urania works first for the World Bank and later for a law firm in New York City. While Urania understandably severs ties with her father, she also ends all communication with her extended family and beloved cousins. In her years as a student, Urania purposefully makes no friends. She studies obsessively and distances herself from others. She remembers dreading the few social engagements she attended as an undergraduate: “[N]o pud[e] dejar de ir algunas veces a fiestas, salir de excursión con muchachos y muchachas, simular que flirteaba [ . . . ], pero regresaba tan exhausta al dormitory por todo lo que debía fingir durante aquellas diversiones que buscaba pretextos para evitarlas” (219). Urania also reflects that in her years as a law student at Harvard she never once went to a party, bar, or dance (219). Her childhood teacher and friend Sister Mary is the only person with whom she retains contact. Throughout the novel, Vargas Llosa uses metaphors to describe Urania’s reclusive nature. She is compared at different times to a planet (11), a desert (564), and an iceberg (228). The metaphor of an iceberg seems particularly appropriate. Urania’s co-worker, Steve Duncan, accuses her of being a “témpano de hielo” (228) when she coldly declines his proposal of marriage. As if proving his point, Urania nearly laughs at his display of emotion when she refuses him. Like an iceberg, nothing can approach Urania because of the enormous (emotional) weight hidden under the surface. Though Urania has never shared her childhood trauma with anyone, Duncan correctly guesses that there is more to Urania than appears. While years have passed since the night Urania spent in Trujillo’s mansion, the emotional scars from that experience are ever-present. Urania reviews the event in her mind and comes to understand the role her trauma has played in her need both to drive men away and to excel at her studies and career. Reflecting later on her conversation with Duncan, Urania notes that she has done well at everything in life, “menos en ser feliz” (230). Urania’s coolness suggests that she has lost the ability to relate with others. Carol Gillian explains that female thinking often reflects an awareness of others especially in problem solving and decision making situations. Women tend to show a heightened consciousness to the needs of the people in their lives and feel a responsibility to help and care for them. Gilligan writes, “[I]n the different voice of women lays the truth of an ethic of care, the tie between relationships and responsibility, and the origins of aggression in the failure of connection” (173). In a similar vein, Simon Baron-Cohen describes differences between male and female brains. He suggests that the male brain is more prone to categorization, while the female one is skilled at empathizing. He writes, “[F]ar more women than men report that they frequently share the emotional distress of their friends. Women also show more comforting behavior, even of strangers […] (31). Urania, however is unaware of others’ feelings. Her cold refusal of Duncan is one example of her inability to consider or notice his emotions, and explains her laughter of surprise over his pain. Given Urania’s emotional distance, her isolation may not initially appear problematic or even undesirable to her. Early in the novel, Urania acts as though the lack of connection in her life does not bother her. As a literary character, Urania almost stereotypically fulfills the role of the spinster. Naomi Braun Rosenthal explains that spinsters were often seen as workaholics who selfishly preferred work to people (ix). In her conversation with her father, Urania acts indifferently about not being married. Though later she confesses that she is miserable and alone, she dons the façade of an independent woman with no need for others: La ventaja de haberme quedado soltera, papá. ¿Sabías, no? Tú hijita se quedó para vestir santos. Así decías tú: <<¡Qué gran fracaso! ¡No pescó marido!>>. Yo tampoco, papá. Mejor dicho, no quise. Tuve propuestas. En la Universidad. En el Banco Mundial. En el bufete. Figúrate que todavía se me aparece de pronto un pretendiente. ¡Con cuarenta y nueve años de encima! No es tan terrible ser solterona. Por ejemplo, dispongo de tiempo para leer, en vez de estar atendiendo al marido, a los hijitos. (72) 11 For a more in-depth discussion on the spinster in literature, see Naomi Braun Rosenthal’s *Spinster Tales and Womanly Possibilities*, 2002. Because of Urania’s lack of emotion, as well as for her intellectualism and professional success, Stephen Henighan suggests that Urania’s personality does not reflect traditional female values. He describes Urania as a, “creación de un personaje asexual, una mujer sin vida afectiva, un ‘hombre honorario’ que comparte las ambiciones y los afanes literarios de los protagonistas masculinos de las novelas anteriores de Vargas Llosa” (377). While Urania’s character may seem outwardly unfeminine and cold, she later reveals deeply felt desires for connection and relationships. For example, when Urania finally shares the story of her rape with her extended family, she admits that not marrying or having a family has been a personal tragedy for her: [E]stoy vacía y llena de miedo, todavía. Como esos viejos de New York que se pasan el día en los parques, mirando la nada. Trabajar, trabajar, trabajar hasta caer rendida. No es para que me envidien, te aseguro. Yo las envidio a ustedes, más bien. Sí, sí, ya sé, tienen problemas, apuros, decepciones. Pero, también, una familia, una pareja, hijos, parientes, un país. Esas cosas llenan la vida. (564) Urania’s fears cause her to suppress her desires for relationships, but they are still a part of her. Unable to recognize or realize her inner feelings, she is disconnected from her true nature. Urania’s inner detachment is illustrated in her choice of study. She explains that she elected to study law simply because it was the first thing to come to mind: “Pero Urania acababa de decir “abogacía” porque fue lo primero que se le vino a la boca, hubiera podido decir Medicina, Economía o Biología” (220). Urania’s decision was not founded on an innate desire to help others hurt like her or because she particularly enjoyed law, but because work and school are simply a means to stay busy. Although Urania tries to hide the void in her life, she ultimately admits that she is unhappy. Unfortunately, she refuses to do the one thing that would likely help her the most—share her story. Urania’s life is deeply affected by her traumatic experience. She devotes years of her limited free time to an exhaustive study of the regime, and yet she does not disclose this part of her life with others. In the novel, Urania tells her father that she never speaks of her rape (159). The lack of connection in her life and her silence about her personal history create a vicious cycle. Unable to form relationships, she has no one to share her story with, and because she does not communicate, she cannot open up about herself and create meaningful friendships. Writing of the often-therapeutic nature of sharing trauma with others, Susan J. Brison writes, The communicative act of bearing witness to traumatic events not only transforms traumatic memories into narratives that can then be integrated into the survivor’s sense of self and view of the world, but it also reintegrates the survivor into a community, reestablishing bonds of trust and faith in others. (xi) Though Urania does eventually communicate with her family at the end of the novel, for thirty-five years she remains silent and does not benefit from appropriately sharing her story. Writing about holocaust survivors, Dori Laub tells the story of a woman who lost everything during World War II. Her life after the Holocaust in many ways resembles Urania’s. Laub describes how in the proceeding years she never spoke of her tragic losses, even with the family and children she has afterward. As a result she “constructed a life in such a fated way, that it came to be a testimony to her loneliness and bereavement, in spite of the fact that her world was filled with living people [. . .]” (63). Had this woman been able to share her experiences, she may have relieved some of her inner burdens. Laub also writes, None find peace in silence, even when it is their choice to remain silent. Moreover, survivors who do not tell their story become victims of a distorted memory, that is, of a forcibly imposed ‘external evil,’ which causes an endless struggle with and over a delusion. The “not telling” of a story serves as a perpetuation of its tyranny. The events become more and more distorted in their silent retention and pervasively invade and contaminate the survivor’s daily life. (64) By not telling her story, Urania unwittingly allows the past to rule over her and her actions. Considering the mental anguish she endures, her behavior towards Duncan is more comprehensible. While Urania’s story appears to have a positive final twist, Vargas Llosa emphasizes that she is overly traumatized and is unable to share her story for many years. Considering the source of Urania’s trauma helps explain her isolation and silence. In many ways, Vargas Llosa sums up Urania’s story with the line, “A mí, papá y Su Excelencia me volvieron un desierto” (564). In this sentence, Urania describes both the nature of her problem as well as what caused it. She explains that her emptiness and isolation were caused by the two individuals who held the responsibility for protecting her. Under extreme pressure, Urania’s father chose to sacrifice his daughter’s innocence in an attempt to make amends with Trujillo. Prior to this despicable act, Agustín Cabral, Urania’s father, actually had a healthy and loving relationship with --- 12 Although Cabral’s role as a victimizer is not diminished in the novel, Vargas Llosa also shows that Cabral had limited options during the Trujillo Era. Cabral is described as a highly intelligent and hardworking individual. Vargas Llosa explains that for a man such as Cabral it would be difficult to escape the regime. One important line in the novel states, “Lo peor que puede pasarle a un dominicano es ser inteligente o capaz. [. . .] Porque, entonces, tarde o temprano, Trujillo lo llamará a servirle [. . .]” (207). During the Trujillato, few people could avoid an allegiance with Trujillo. Salvador Estrella Sadhala, one of Trujillo’s assassins, comments that the rich and talented were recruited to support Trujillo and the poor and middle class often worked in his factories or businesses (207). Thus the regime affected society on all levels. Understanding the ubiquitous nature of Trujillo’s government helps explain Cabral’s involvement with it and the pressure he was under. his daughter. Because Urania’s mother passed away, she was raised by her father. Urania remembers, “Tu padre había sido tu padre y tu madre aquellos años. Por eso lo habías querido tanto. Por eso te había dolido tanto, Urania” (23). Cabral’s complicity in Urania’s rape scars her almost as much as the act itself. Urania’s memories of her trauma show the pain she feels as she realizes her father’s involvement. When she first arrives at Trujillo’s mansion, known as La Casa de Caoba, she still does not understand why she is there. Cabral had simply told his daughter she was going to a party. Slowly Urania begins to understand: Su incredulidad irrealizaba lo que le estaba ocurriendo. [. . .] ¿El senador Agustín Cabral la enviaba, ofrenda viva, al Benefactor y Padre de la Patria Nueva? Sí, no le cabía la menor duda, su padre había preparado esto con Manuel Alfonso. Y, sin embargo, quería dudar. (550) Urania is overcome by the fact that her beloved father would betray her and she becomes full of hatred towards him. She even contemplates committing suicide in Trujillo’s mansion, but decides against it because she wants to live to see her father suffer for his actions (551). Cabral’s damaged relationship with his daughter is part of the reason Urania becomes so isolated. Father-daughter relationships shape a developing girl in many ways. In The Wounded Woman: Healing the Father-Daughter Relationship, psychologist Linda Schierse Leonard explains, As a daughter grows up, her emotional and spiritual growth is deeply affected by her relationship to her father. He is the first masculine figure in her life and is a prime shaper of the way she relates to the masculine side of herself and ultimately to men. Since he is “other,” i.e., different from herself and her mother, he also shapes her differentness, her uniqueness and individuality. The way he relates to her femininity will affect the way she grows into womanhood. (11) By sacrificing Urania to Trujillo, Cabral devalues Urania and reduces her femininity to something that he can control for his own personal reasons. His actions deeply scar her. In her book on father-daughter relationships, Leonard includes a section on the Greek drama *Iphigenia in Aulis* by Euripides. This play bears striking similarities to Urania’s story in *La fiesta del Chivo*. In the drama, King Agamemnon leads the Greek army against Troy. Though the Greek ships are ready to sail for Troy, there is no wind. By consulting a seer, Agamemnon discovers that the poor sailing conditions were caused by the goddess Artemis, whom he has offended. In order to regain the wind, Agamemnon is told he must sacrifice his beloved daughter Iphigenia. Agamemnon debates whether or not to go through with the act. He knows the Greek army is excited for battle and may mutiny if they do not sail against Troy. Agamemnon’s wife and daughter discover the plan and try to dissuade him, but in the end he becomes convinced that he must go against Troy for the greater good of Greece and for his own glory. In the end, Iphigenia is sacrificed and the winds return. *Iphigenia in Aulis* represents a culture that diminishes the value of women. Agamemnon’s actions indicate that he views his daughter as a possession. Schierse Leonard writes, “The father-daughter sacrifice has its roots in the dominance of masculine power over the feminine” (30). Agamemnon also acts out of self-interest. He desires the continued power and glory he believes this battle will bring him. Similarly, Cabral views his daughter as a possession when he offers her to Trujillo in order to restore his relationship with the dictator. Though Trujillo’s mysterious break with Cabral appears to be no more than a loyalty test, Cabral becomes desperate with the loss of his connection to the Generalissimo. Sabine Köllman comments that Cabral sees Trujillo as a father figure, which explains his anxiety over his break with the dictator (279). Trujillo created a system that kept his officials constantly vying for his attention and approbation. Urania comments on the almost paternal (and abusive) relationship he created with his collaborators when she explains her confusion over why they would constantly endure his abuse and in the end “quererlo, como llegan a querer los hijos a los padres autoritarios, a convencerse de que azotes y castigos son por su bien” (82). Tragically, Cabral subordinates his daughter to his (symbolic) father and, like Trujillo, becomes a poor father himself. Through his actions, he places greater value on the masculine, devaluing his daughter and the feminine. Urania’s strained relationship with her father and her fear of Trujillo, cause her to create defenses which limit her growth and prevent her from establishing friendship. When women have suffered a difficult relationship with their fathers they often create protective walls. Schierse Leonard uses the metaphor of the ‘armored Amazon’ to describe one type of defense women acquire: Developmentally, I find that this pattern arises as a reaction against inadequate fathering, occurring either on the personal or cultural level. In reacting against the negligent father such women often identify on the ego level with the masculine or fathering function themselves. [. . .] So they build up a strong masculine ego identity through achievement or fighting for a cause of being in control and laying down the law themselves [. . .]. (17) Like the ‘armored Amazon’ that Schierse Leonard describes, Urania focuses on achievement and being in control. She excels in her studies and lives a highly structured lifestyle. Out of fear and pain over the wounds inflicted on her both by her father and Trujillo, Urania sacrifices her feminine ability to connect and adopts, instead, a cold demeanor as a means of self-defense. However, Urania’s adopted rigidity comes with a high price, which she recognizes later in her life. She describes herself as “vacía” (564) because she is unable to have the fulfillment that relationships might bring. Eventually Urania’s wall of self-defense becomes a prison. Schierse Leonard explains that a woman becomes “trapped in an ‘Amazon armor,’ a powerful persona which may not correspond to her basic personality since it has been formed out of a reaction and not out of her inner feminine center” (61). An individual may become overpowered by a false persona she creates in order to self-protect. Women, like Urania, who take on a more rigid personality, often stifle their feminine identity. This is the case when Steven Duncan, Urania’s co-worker at the World Bank, accuses her of not being Dominican. Dominicans are known for warmth, friendship, and reaching out to others. When Urania coldly and indifferently turns down Duncan’s proposal of marriage, he tells her, “Tú sí que no pareces dominicana. Yo lo parezco más que tú” (229). Though Urania acts as though she does not care about his accusation, she remembers the conversation years afterward and recalls that Duncan later married another coworker. Urania’s memories of the details of her one-sided relationship with Duncan suggest regret over not being able to express love and shows that her inner desires are trapped behind protective walls. The damage Urania experiences from her impaired relationship with her father is also compounded by the involvement of the dictator. In addition to the patriarchal relationship he had with those close to him, such as Cabral, Trujillo can also be viewed as a father figure to the entire country and to Urania. Trujillo was referred to as “El Benefactor de la Patria,” describing the stability and support he brought to the country. His hands-on command over the nation’s economy, press, and military created an intensely personal-style of leadership. By law all Dominicans also had a plaque in their homes, reading, “En esta casa Trujillo es el Jefe.” Vargas Llosa comments that this practice placed Trujillo symbolically within every household (qtd in Barnabé 4). López-Calvo points out that there is also an interesting linguistic connection between the terms “dictator” and “father.” The Greek word for father, from which “despot” derives, means “head of household,” referring to the “master of children or slaves” (5). Dictatorships such as Trujillo’s frequently treated the people as such, making decisions for them and depriving them of basic liberties and agency. For Urania, who as a child was sheltered from the true nature of Trujillo, the dictator could easily be seen as a symbolic father-figure. Vargas Llosa seems to make this connection during the rape scene that takes place in Trujillo’s Casa de Caoba. Urania thinks to herself, “¿El senador Agustín Cabral la enviaba, ofrenda viva, al Benefactor y Padre de la Patria Nueva?” (550, my emphasis). Trujillo’s role as a paternal figure makes his abuse of Urania more emotionally traumatic. It is interesting that when Urania’s aunt, Adelina, asks Urania how she can speak disrespectfully about her father, Urania says, “Porque no era tan buen padre como crees, tía Adelina” (299). Here, Urania’s words about Cabral can also apply to Trujillo. While Trujillo played the role of father-figure, he abused his power. Vargas Llosa uses Urania’s experience to express criticism of a regime that did not respect women. Trujillo was a well-know womanizer. In his government, women often became objects of pleasure or prestige. Lauren Derby explains that Trujillo used women to build his reputation: “His charisma was founded as much on the concrete numbers of women he acquired (and their class status) as it was on violence and the near mythological fear he inspired by eliminating men” (1113). Köllmann also comments that the connection between patriarchy and dictatorship has been explored in other works of Latin American fiction, most prominently in García Márquez’s El otoño de la Patriarca (276, see note). Trujillo’s degrading treatment of women is one of the reasons Vargas Llosa chose to include Urania’s character in *La fiesta del Chivo*. Referring to Trujillo’s government, Vargas Llosa explains, *La dictadura fue particularmente cruel con la mujer. Como todas las dictaduras latinoamericanas tuvo un contenido machista; el machismo es un fenómeno latinoamericano. Pero eso, imbricado con lo que es un régimen autoritario, de poder absoluto, convierte a la mujer realmente en un objeto vulnerable a los peores atropellos.* (qtd in Barnabé 4) Vargas Llosa was so concerned by Trujillo’s mistreatment of women that the title of the novel actually refers to Urania’s rape. Williams explains that the word *fiesta* from the title refers to the celebration over the assassination of Trujillo as well as to Urania because her father tells her she is going to a *fiesta* when he sends her to Trujillo’s mansion (*Otra historia* 269-70). Williams points out that the story of Urania is intricately connected to the whole novel. Metaphorically, the rape of Urania symbolizes the rape of the country by the dictator. In many ways her story encapsulates Vargas Llosa’s criticism of Trujillo. In the novel, Trujillo’s misogynistic attitude towards women eventually affects other people in society, as evidenced through the story of Agustín Cabral. Vargas Llosa includes several other examples of individuals who are negatively influenced by Trujillo. For instance, Urania discusses a story with her now-aged father about don Froilán, one of their neighbors when Urania was a child. At a party, with Froilán in attendance, Trujillo boasts about having an affair with his wife. In this situation, Froilán, though certainly humiliated, says nothing and acts undisturbed. Vargas Llosa incorporates several similar anecdotes in *La fiesta del Chivo*, describing women who were abused and left unprotected by the men in their lives. The story of Rosalía Perdomo, the daughter of a rich family, is another example. Though Rosalía is very young, Ramfis Trujillo, the son of the dictator, notices her and flirts with her. Rosalía is unsuspecting of his character and innocently leaves school one day to accompany Ramfis and his friends. She is brutally raped and almost left for dead. Though Urania says the story is well-known in society (150), Ramfis is never punished for his actions. Through examples like this, Vargas Llosa shows that the machismo of the dictatorship influenced others, as in the case of Agustín Cabral. In addition to the widespread disparagement of women, in *La fiesta del Chivo* there is also a surprising lack of female presence. The principle characters of the novel are predominately male, with the exception of Urania. The other central characters are Trujillo, and the group of men who plan and carry out his assassination. The individuals in Trujillo’s storyline are his male officials, including the despicable leader of the SIM, Jonny Abbes García, and the controversial politician Joaquín Balaguer. Possibly the most notable absence of female presence is in Urania’s life. The fact that Urania was raised without a mother (her mother died in a car accident when Urania was young) symbolizes a general lack of women’s influence in society. The story of Urania’s neighbor doña Froilán suggests that even the women present in her life were (forcibly) connected to the regime. Urania mentions that, as a child, doña Froilán became a maternal figure for her: “Urania la quería [a doña Froilán] por lo cariñoso que era, por los regalos, porque la llevaba al Country Club a bañarse en la piscina, y, sobre todo, por haber sido amiga de su mamá. Imaginaba que, si no se hubiera ido al cielo, su madre sería tan bella y señorial como [ella]” (75). Although as a child Urania admires her neighbor, she later realizes that doña Froilán was not a positive female role model. While visiting doña Froilán on one occasion, Urania notices that Trujillo comes to the Froilán residence while the husband is away. Urania, at the time, is too young to understand the situation and is quickly sent home without an explanation. This initially confusing incident marks her and she reflects on it later in life while talking with her father. Vargas Llosa uses the lack of women and positive female role models in the life of his protagonist to illustrate the marginalization of women under the dictatorship.⁴ The dominance of male characters in *La fiesta del Chivo* shows a lack of balance, where exaggerated masculine values reach dangerous extremes. Writing about male/female priorities, Gilligan notes, “Power and separation secure the man in an identity achieved through work, but they leave him at a distance from others, who seem in some sense out of his sight” (163). In a similar vein, Baron-Cohen comments that “men tend to value power, politics, and competition” (32). It is interesting that values such as power and competition, when taken to extremes, can result in tyranny. While both male and female priorities are needed in society, they must balance each other. Gilligan writes, > [M]ale and female voices typically speak of the importance of different truths, the former through the role of separation as it defines and empowers the self, the latter of the ongoing process of attachment that creates and sustains the human community. (156) Gilligan asserts that both sets of values are considered beneficial and necessary. Indeed, a healthy society would balance the two “truths” described by Gilligan. Unfortunately, in the society depicted in *La fiesta del Chivo*, men and women cannot balance each other because women are not respected. In many cases in *La fiesta del Chivo*, women are silenced, abused, or absent. ⁴ There is one notable exception: Sister Mary does become a friend and female role model to Urania. She greatly aids Urania in her escape to the United States. Still, the fact that the two maternal figures in her life as either absent or dominated by the regime is very significant. The machismo that characterized the Trujillo government is unfortunately not new to Latin American politics. In *La fiesta del Chivo*, Vargas Llosa traces the evils of dictatorship to Latin American history. Urania tells her father, “En esos treinta y un años cristalizó todo lo malo que arrastrábamos, desde la conquista” (72). While this quote may refer to many things, it is significant that the Conquest often reinforced gender inequality. In *Reading Columbus*, Margarita Zamora writes of the connection between gender and the Discovery. She explains, Columbian writing ultimately interprets the difference between Europeans and Indians as a gender difference, not in a sexual or biological sense, but as a difference ideologized and inscribed onto a cultural economy where gender becomes fundamentally a question of value, power, and dominance. (173) Zamora explains how the native inhabitants of the New World, as well as the New World itself, were typically depicted in art and letters as female, while the conquistadors were portrayed as masculine. Thus male domination became an important metaphor in describing the Conquest. In a similar way, the rape of Urania becomes an essential parallel for describing the Trujillo dictatorship. As Williams points out, it is significant that the title of the novel refers to her rape. --- 15 Another interesting connection to the Conquest is described by López-Calvo. He writes, [T]he background of the Spanish conquest of America is a recurring topic of the *Trujillato* narratives. While it usually remains as a backdrop to the present situation of the Dominican Republic, the constant allusion to the colonial past clearly implies that these authors see the plague of caudillos and dictators in Latin America as a direct consequence or continuation of the *repartimientos* and *encomiendas* imposed by Spain during the colonial times. (39) López-Calvo refers to the political system of government—*repartimientos* and *encomiendas*—during the Conquest and colonization, where strong men or caudillos where given political power. As López-Calvo suggests, many authors see this early system of governance as the foundation for the Latin American dictator. The *encomienda* system encouraged the development of the ‘strong man’ and intensely personalized leadership, such as Trujillo’s. Trujillo is like the conquistador who overpowers the country. Rape is associated with control and force. Likewise, Trujillo can be characterized for his abuse of the agency of the people.\textsuperscript{16} In the rape metaphor Urania represents her country, which is controlled by the dictator. In addition, she also becomes a symbol of Latin America. The conclusion to Urania’s story is significant, and controversial, because her development can be seen as a metaphor for Vargas Llosa’s vision of Latin America’s future. The question arises—will Latin America, and Urania, remain trapped by despotic leaders, or is there hope of freedom? Michael Valdez Moses suggests that Vargas Llosa’s view of Latin American politics (as well as the ending to Urania’s story) is pessimistic: What sets \textit{The Feast of the Goat} apart from the other great Latin American dictator novels of García Márquez and Carpentier (works that conclude optimistically and, in good socialist fashion, in anticipation that the age of the tyrant is at last coming to its end) is its chilling sense that the past will continue to haunt both the present and the future. (70) Valdez Moses suggests that if Vargas Llosa is less than optimistic, it is most likely because he has seen the rise, fall, and reinstatement of new despotic leaders in Latin America (6). Concerning Urania, Valdez Moses also writes, “Nor does Urania’s fate provide much greater solace. She is forever marked and deformed by Trujillo’s tyranny” (70). Valdez Moses is not the only person to suggest that Urania’s outcome is tragic. López-Calvo also writes that Urania is “trapped in her own mental torment” and that she “never truly becomes an active agent of her own liberation” (38). Part of the pessimism regarding Urania’s conclusion can be related to an incident in the last page of the novel. While Urania is returning to her hotel from \textsuperscript{16} The loss of agency is a constant theme in \textit{La fiesta del Chivo} and one of the principle motivations of Trujillo’s assassins. For example, one of the conspirators says, “[E]l Chivo había quitado a los hombres el atributo sagrado que les concedió Dios: el libre alberdrio” (207). visiting her cousins, a slightly inebriated tourist offers to buy her a drink. Urania overreacts by telling him, “Get out of my way you dirty drunk” (569). This scene suggests that in spite of her return to her native country and her visit with her father and family, that she still carries emotional baggage from the past. Henighan writes, “Estas últimas escenas confirman que [. . .] Urania todavía le debe sus rasgos personales al mundo de 1961” (378). Certainly Vargas Llosa suggests that Urania is in no way entirely cured of her past trauma. But while the conclusion of Urania’s story can be seen as pessimistic, there is also an indication of a positive resolution for her. When seen in the light of her developmental struggles, the final pages of Urania’s story actually demonstrate incredible growth and change. In the concluding chapter of *La fiesta del Chivo*, Urania breaks her thirty-five year silence and tells her story to several family members consisting of her aunt, cousins, and her cousin’s daughter Marianita. By sharing her story, Urania begins to re-develop relationships with her family members. As Susan J. Brison comments, the act of telling one’s story “reintegrates the survivor into a community, reestablishing bonds of trust and faith in others” (xi). Urania is a victim who has deeply desired human contact, but who has been kept from it by the self-protecting walls she has created. By communicating with her family, Urania reestablishes meaningful relationships with them. Though Urania expresses concern for sharing such a difficult story, her cousin reassures her, “Qué tú dices, muchacha. Ahora entiendo qué pasó contigo, ese silencio que nos dejaba tan dolidas. Por favor, Urania, vuelve a vernos. Somos tu familia, éste es tu país” (568). Marianita tells Urania, “Yo a ti te voy a querer mucho, tía Urania. [. . .] Te voy a escribir todos los meses. No importa si no me contestas” (568). Following this touching scene with her family, Urania leaves and returns to her hotel to pack, but --- 17 Henighan does admit that Urania grows, but feels she not change significantly and suggests that the conclusion to her story is pessimistic. pauses for a moment. In the last line of the novel Urania decides, “Si Marianita\textsuperscript{18} me escribe, le contestaré todas las cartas” (569).\textsuperscript{19} Urania’s decision demonstrates important growth. During the entire novel until this moment, Vargas Llosa characterizes Urania as distant and unconnected to others. The fact that the final scenes of the novel show such a dramatic change in Urania is significant. By suggesting that his protagonist is dynamic, Vargas Llosa also expresses openness in his views of Latin America in general. Though the bloody aftermath of the Trujillo dictatorship is well-chronicled in the novel, Vargas Llosa suggests through Urania that the past does not have to reoccur in the present. Just as Urania overcomes some of her demons, Latin America may be able to break the cycle of dictatorship. If Urania’s growth can be seen as symbolic of Latin American development, these final pages suggest the author’s hope for Latin America. \textsuperscript{18} Marianita’s name has caused me some reflection. It is interesting that two critical figures in Urania’s well-being are Sister Mary and Marianita. Sister Mary secures a scholarship for Urania and is the only person that Urania really communicates with for thirty-five years. Marianita is the family member who is able to help Urania decide to change and maintain her newly reestablished relationships with her family. These women are life-lines for Urania. It is possible their names are connected to the Virgin Mary, a symbol of salvation. Whether intentional or accidental, religious or otherwise, this interesting correlation seems to suggest that Urania’s salvation comes through connection and relationships. CONCLUSION Both Julia Alvarez and Mario Vargas Llosa make female experience an important theme in their novels addressing the Trujillo dictatorship. This thesis examines how ideas of female developmental psychology lend to a more profound understanding of the novels *In the Time of the Butterflies* and *La fiesta del Chivo*. In the analysis of these books I have often relied on the findings of Carol Gilligan to focus on the importance of relationships in the process of female maturation. Alvarez and Vargas Llosa utilize the idea of connection to others to show the development of their protagonists. In the first novel, *In the Time of the Butterflies*, Alvarez illustrates the value of relationships as the Mirabals experience significant rites of passage. Some key examples include Minerva’s first menstruation and Patria’s call to the revolution. Through these and other events the Mirabals mature and thus increase in their ability to care for others. Mate comforts women struggling in prison when she herself endures many trials, Minerva reaches out to her illegitimate sisters and helps Margarita pay for her education, Patria joins the revolution knowing the dangers her choice places on her family, and Dedé becomes a mother for her deceased sisters’ children. The Mirabal siblings’ ability to show kindness contrasts with Trujillo’s style of governance, which Alvarez describes as violent, selfish and immature. Although Trujillo falls short, Alvarez shows true strength through the Mirabal sisters’ selflessness and warmth. Vargas Llosa, like Alvarez, focuses on female development in *La fiesta del Chivo*. His protagonist, however, suffers a traumatic initiation that leads to inhibited growth. The novel begins with the image of a woman who at the age of forty-nine is lonely and deeply wounded because of her past. Vargas Llosa emphasizes Urania’s isolation thereby stressing the seriousness of the emotional injury she received at a formative time in her life. Urania is thus prevented from developing along healthy paths of female maturation. She suffers inner frustration and lack of fulfillment and prevents others from being a part of her life. Vargas Llosa uses Urania’s truncated development to depict the unjust treatment of women during the dictatorship. Indeed, the Dominican Republic of Urania’s youth is described as highly machista and women in Vargas Llosa’s novel are either absent or controlled by Trujillo and those who work for him. More importantly, the Generalissimo’s domination of women such as Urania is symbolic of the unchecked power he had over the Dominican Republic for thirty-one years and his rape of Urania is a metaphor for the suffering of all Dominicans during his reign. Throughout that time many were denied basic rights and Urania’s story shares insight into their struggles. Though still scarred, years pass and Urania is able to look beyond the trauma she suffered in order to reach out to her family. Her progress at the novel’s conclusion represents hope that the cycle of tyranny can be broken. Although Urania’s story differs greatly from the Mirabals’, there is value in comparing the two. Ironically, the differences between the Mirabals and Urania often speak of similar truths. The role of connection in the protagonists’ development is crucial to both stories, although it is often expressed differently. For example, Alvarez’s characters are frequently able to look past the abuse they suffer and respond to the needs of others in their lives. In the Time of the Butterflies focuses on the strengths the Mirabals develop as they mature into women who actively take a stance against Trujillo’s oppressive dictatorship. In contrast, Urania is traumatized to a point that she is unable to speak of what happened to her. She closes herself off from family members, friends and even her own country as she lives in exile for thirty-five years. Urania’s stunted growth is evidenced by her lack of connection and reflects the debilitating nature of dictatorship on the individual. It is noteworthy, however, that some healing occurs as Urania begins to rebuild her relationship with her family. While the experiences of all the female protagonists are quite different, *In the Time of the Butterflies* and *La fiesta del Chivo* both attest to the power of connection in women’s lives. The values that shape the Mirabal sisters and Urania Cabral are particularly meaningful in relation to dictatorship. The two novels examined in this thesis address the world-wide issue of the mistreatment of women under oppressive governments. They depict how detrimental abusive regimes can be to women and to the individual. The stories of the Mirabals and Urania show that the discrimination of women is a tragedy that has serious implications in society. Where women are not valued their important perspectives may be lost. In particular, Alvarez emphasizes the contributions women can make by expounding on the Mirabals’ values. In contrast, Vargas Llosa shows what can happen when female priorities are lost or diminished. By including the stories of women in their discussion of dictatorship, Alvarez and Vargas Llosa show that female experience and perspectives are valuable and essential to building a healthy community. *In the Time of the Butterflies* and *La fiesta del Chivo* reflect the historical reality of machismo in Latin America under dictatorships. In *La fiesta del Chivo* Urania comments that many of the evils of the Trujillo dictatorship trace their roots to colonization. Indeed, the colonial tradition of dividing land among a few powerful men fostered the creation of the Latin American dictator. While dictatorship continues to exist in some countries today, there is some indication of change. It is significant that Latin America has seen a rise in democratically-elected female presidents in recent years including Michelle Bachelet of Chile (2006-2010), Cristina Fernández de Kirchner (2007-present) of Argentina and the newly elected Dilma Rousseff of Brazil. This phenomenon suggests a positive change in the Latin American political system regarding the status of women. Perhaps the optimistic twist at the end of *La fiesta del Chivo* is not unfounded and the cycle of dictatorship and its accompanying machismo may be eroding in Latin America as women find their voice in the political system.
The transition scale $L_t$ from balanced geostrophic motions to unbalanced wave motions, including near-inertial flows, internal tides, and inertia–gravity wave continuum, is explored using the output from a global 1/48° horizontal resolution Massachusetts Institute of Technology general circulation model (MITgcm) simulation. Defined as the wavelength with equal balanced and unbalanced motion kinetic energy (KE) spectral density, $L_t$ is detected to be geographically highly inhomogeneous: it falls below 40 km in the western boundary current and Antarctic Circumpolar Current regions, increases to 40–100 km in the interior subtropical and subpolar gyres, and exceeds, in general, 200 km in the tropical oceans. With the exception of the Pacific and Indian sectors of the Southern Ocean, the seasonal KE fluctuations of the surface balanced and unbalanced motions are out of phase because of the occurrence of mixed layer instability in winter and trapping of unbalanced motion KE in shallow mixed layer in summer. The combined effect of these seasonal changes renders $L_t$ to be 20 km during winter in 80% of the Northern Hemisphere oceans between 25° and 45° N and all of the Southern Hemisphere oceans south of 25° S. The transition scale’s geographical and seasonal changes are highly relevant to the forthcoming Surface Water and Ocean Topography (SWOT) mission. To improve the detection of balanced submesoscale signals from SWOT, especially in the tropical oceans, efforts to remove stationary internal tidal signals are called for. 1. Introduction Advent of nadir-looking satellite altimetry in the 1990s has revolutionized our ability to measure with high precision the global sea surface height (SSH) field and to explore, through geostrophy, the upper-ocean circulation dynamics. This exploration has significantly advanced our understanding of mesoscale oceanic variability; see Fu et al. (2010) and Morrow and Le Traon (2012) for comprehensive reviews. A critical limitation of the nadir-looking altimeters is their 100–300-km spacing between the satellite ground tracks. Even with combined data merged from multiple altimeters, the spatial resolution in a two-dimensional SSH map is typically on the order of 200 km in wavelength (Ducet et al. 2000; Chelton et al. 2011). This length scale is inadequate to fully capture the mesoscale oceanic signals that contain 90% of the kinetic energy of the ocean (Ferrari and Wunsch 2009) and misses completely the submesoscales that have length scales shorter than the Rossby radius of deformation. With the wide-swath radar interferometry, the next-generation Surface Water and Ocean Topography (SWOT) satellite will improve the measured SSH resolution potentially down to the spectral wavelength of 15 km, allowing us to investigate for the first time the global upper-ocean circulation variability at the short mesoscale and submesoscale ranges (Fu and Ubelmann 2010). Dynamically, upper-ocean processes with length scales of \( O(15–200) \) km are important because they determine the equilibrium state of the upper ocean through the turbulent kinetic energy cascade and energy dissipation (e.g., Ferrari and Wunsch 2009; McWilliams 2016). They are also crucial to how the surface ocean communicates with the subsurface interior ocean, affecting the mixed layer evolution and upper-ocean thermal anomalies (e.g., Lapeyre et al. 2006; Capet et al. 2008; Thomas et al. 2008; Klein et al. 2008). Because of the correlation existing between surface and interior ocean potential vorticity anomalies, meso- and submesoscale SSH information in the 15–200-km range can potentially be used to reconstruct the threedimensional, upper-ocean circulation structures, including the balanced vertical velocity field (Lapeyre and Klein 2006). A rich literature is available relating to this research topic and an up-to-date review of the topic and its application to the planned SWOT SSH measurements can be found in Qiu et al. (2016). With the decrease in horizontal scale, the kinetic energy level of the geostrophically balanced motion has been observed to weaken proportional to \( k_h^{-2} \sim k_h^{-3} \), where \( k_h \) is the horizontal wavenumber (Callies and Ferrari 2013; Bühler et al. 2014; Rocha et al. 2016a). For the 15–200-km range pertinent to the SWOT mission, it is possible that the balanced motion can lose its dominance and be overtaken by the unbalanced wave motions, including near-inertial flows, internal tides, and inertia–gravity waves. In such a case, the altimeter-measured SSH information can no longer be used readily to infer the time-varying surface geostrophic flows. The transition scale separating the balanced and unbalanced motions was explored in our recent analyses of repeat shipboard ADCP measurements along 137°E across the wind-driven tropical and subtropical gyres in the northwestern Pacific (Qiu et al. 2017). By analyzing the repeat ADCP surveys from 2004 to 2016, we found that the observed transition scale depends sensitively on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current band of Kuroshio, the transition scale is short, \(<15 \) km, and it increases to \( \sim 50 \) km in the moderately unstable Subtropical Countercurrent (STCC) band in the central subtropical gyre. Along the path of relatively stable North Equatorial Current, the transition scale was observed to exceed 200 km. In addition to these geographical changes, the repeat ADCP measurements along 137°E further revealed that the transition scale is decreased in winter and lengthened in summer in the Kuroshio and STCC bands because of the occurrence of mixed layer instability in winter (Sasaki et al. 2014; Qiu et al. 2014). No apparent seasonal difference in transition scale was observed in the tropical gyre. Information about the seasonally and geographically varying transition scale is important for the SWOT mission because it provides an important length scale measure below which the SSH data may no longer be used to accurately infer the surface geostrophic velocity. To expand our analyses on transition scale to the global ocean, we adopt in this study the state-of-the-art global ocean simulation output from the Massachusetts Institute of Technology general circulation model (MITgcm) llc4320. With its horizontal resolution at 1/48° and with the realistic tidal forcings, the output of llc4320 has been used recently to explore the submesoscale dynamics in different parts of the World Ocean (Rocha et al. 2016a,b), to compare internal gravity wave SSH spectra against globally available moored measurements (Savage et al. 2017a,b), and to design calibration and validation (CalVal) approaches for SWOT-measured SSH signals (Wang et al. 2018). This paper is organized as follows: In section 2, we provide a brief description about the MITgcm llc4320; its performance in resolving the global mesoscale eddy variability is compared to that observed by available nadir-looking satellite altimeters. In section 3, we introduce the transition scale based on kinetic energy (KE) equality of the balanced and unbalanced motions and examine its geographical variations. Seasonal variations in transition scale are examined in section 4 where opposing seasonal contributions from the balanced and unbalanced motions are emphasized. Section 5 explores the transition scale that is based on the SSH variance equality of the balanced and unbalanced motions. Its differences from the KE-based transition scale will be contrasted. In section 6, we summarize the analysis results in the context of the planned SWOT mission and discuss the need to reduce the unbalanced motion KE by removal of stationary internal tidal signals. 2. MITgcm llc4320 simulation The data product analyzed in this study is based on the state-of-the-art global ocean simulation of MITgcm (Marshall et al. 1997) in a latitude–longitude–cap (Ile) configuration with a polar cap that has 4320 × 4320 grid cells. Referred to as llc4320, the model has a 1/48° horizontal resolution and 90 vertical levels. To better resolve the submesoscale upper-ocean variability, the model’s vertical levels have a \( \sim 1\)-m vertical resolution at the surface and increases to \( \sim 30\) m near the 500-m depth. The llc4320 simulation is initialized from the output of the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2), project (Menemenlis et al. 2008), with the subsequent model resolution increased to llc1080 (1/128°), llc2160 (1/248°), and the present llc4320 (1/48°). The llc4320 model is forced by the 6-hourly ERA-Interim atmospheric reanalysis as well as by a synthetic surface pressure field consisting of the 16 most dominant tidal constituents. For our analysis, we use the hourly output of the modeled surface height \( \eta \) and horizontal velocity \((u, v)\) data from 1 November 2011 to 31 October 2012 (366 days). To verify the surface circulation changes modeled in the llc4320 simulation, we use the global SSH anomaly dataset generated by Ssalto/Duacs and distributed by AVISO with support from CNES (http://marine.copernicus.eu/). This dataset merges along-track SSH measurements from all satellite altimeter missions after October 1992 and has a 7-day temporal resolution and a 1/4° longitude Mercator spatial resolution (Ducet et al. 2000). The data period available for this study extends from January 1993 to December 2016. Figure 1 compares the surface eddy kinetic energy (EKE) distribution simulated by llc4320 and that derived from the AVISO SSH product for the period of November 2011–October 2012. For comparison with the AVISO-derived EKE values, we average the llc4320 modeled SSH data into a weekly time series on the 1/4° longitude Mercator grid and compute the EKE assuming geostrophy: \[ EKE = \frac{1}{2} \left[ \left( \frac{g}{f} \frac{\partial \eta}{\partial y} \right)^2 + \left( \frac{g}{f} \frac{\partial \eta}{\partial x} \right)^2 \right], \] where \( g \) is gravitational acceleration, \( f \) is the Coriolis parameter, and \( \eta \) is the SSH anomalies from the mean SSH of November 2011–October 2012. By and large, llc4320 simulates faithfully the mesoscale eddy variability captured by the satellite altimeter missions that have spectral scales larger than \( O(150) \) km (e.g., Chelton et al. 2011). One noticeable discrepancy between the two EKE maps is within the equatorial band of \( \pm 10^\circ \), where the AVISO-derived EKE values in Fig. 1b appear consistently larger than those based on llc4320 (Fig. 1a). One likely reason for this discrepancy can be related to the measurement errors in the AVISO SSH data that are amplified when converting to EKE because of the small \( f \) values within the equatorial band. Evaluating the llc4320’s skill in simulating the unbalanced wave motions is more challenging because of the lack of in situ high-frequency SSH measurements in the World Ocean. By utilizing the hourly dynamic height time series from nine McLane profiler moorings available in the Pacific, North Atlantic, and south Indian Oceans, Savage et al. (2017b) found recently that the wave frequency spectra of SSH variance simulated by llc4320 agreed reasonably well with those observed by the profiler moorings. Given these high-frequency SSH comparisons and those for the mesoscale eddy variability shown in Fig. 1, we believe the llc4320 results are adequate for quantifying the relative importance between the balanced versus unbalanced motions. 3. Balanced–unbalanced motion decomposition and \( L_t \) Delineation of balanced and unbalanced motions can be conducted in several different ways. One common method is to select a temporal filter with the low-pass (high pass) filtered signals regarded as the balanced (unbalanced) motions. For example, Richman et al. (2012) used a 48-h filter in their study on KE spectral slopes relevant to the mesoscale variability. While straightforward in its implementation, such a single-frequency filter may not be ideal for decomposing the balanced and unbalanced motions on the global scale. Figure 2 compares the typical horizontal wavenumber–frequency \((k_h-\nu)\) spectra of surface KE in four representative areas in the Pacific Ocean from the hourly output of llc4320: (i) the highly turbulent Kuroshio Extension, (ii) moderately unstable STCC, (iii) stable North Equatorial Current, and (iv) the tropical southwest Pacific. In the plots, elevated unbalanced motion KE is discernible in the near-inertial, diurnal, and semidiurnal tidal frequency bands as well as along the dispersion curves of inertia–gravity waves (IGWs) of discrete vertical modes: \( \omega^2 = f^2 + c_n^2 k^2 h \) (see white solid lines), where \( c_n \) \((n = 1 \text{ to } 10)\) are evaluated based on the World Ocean Atlas 2013 (WOA2013) climatological temperature–salinity profiles (Locarnini et al. 2013; Zweng et al. 2013). From Fig. 2, it is clear that the cutoff period delineating the balanced and unbalanced motions is highly sensitive to the local inertial period: near the local inertial frequency band, balanced and unbalanced motions can coexist with large and small wavenumbers, respectively. As a result, this renders the adoption of a single-frequency filter, such as the dashed black line showing the 36-h filter, undesirable. In the present study, we adopt a more dynamically based method by defining the balanced (unbalanced) motions as... --- 1 In light of SSH information from the SWOT mission, barotropic tidal signals are removed throughout this study. Specifically, this is done by eliminating the best-fit two-dimensional spatial slopes from the \((u, v)\) data in individual 500 km \times 500 km boxes prior to the spectral wavenumber–frequency decompositions. motions below (above) the lower frequency of either the local tenth vertical-mode IGW dispersion curve or the permissible tides (see thick black lines in Fig. 2). To evaluate the transition scale $L_t$ from balanced to unbalanced motion, we first select the hourly surface $(u, v)$ data from llc4320 in each fixed $500 \times 500$ km box. After removing the best-fit two-dimensional spatial slopes from the $(u, v)$ data and applying a two-dimensional Hanning window, we obtain the horizontal wavenumber–frequency spectrum of surface KE, $\mathcal{E}(k_h, \omega)$, such as those shown in Fig. 2. The transition scale $L_t$ is defined as the wavelength $k_h^{-1}$ at which KE integrated over the balanced motion frequencies; $$\text{KE}_{\text{bal}}(k_h) = \int_{\omega_{yr}}^{\omega_{cr}(k_h)} \mathcal{E}(k_h, \omega) d\omega,$$ is equal to that integrated over the unbalanced motion frequencies $$\text{KE}_{\text{unb}}(k_h) = \int_{\omega_{cr}(k_h)}^{\omega_{Ny}} \mathcal{E}(k_h, \omega) d\omega,$$ where $\omega_{yr}$ denotes the annual frequency, $\omega_{cr}(k_h)$ is the dynamically delineating frequency defined above, and $\omega_{Ny}$ is the Nyquist frequency at 0.5 cph. As an illustration, we plot in Fig. 3 $\text{KE}_{\text{bal}}$ and $\text{KE}_{\text{unb}}$ as a function of $k_h$ in the same four representative boxes as those selected in Fig. 2. By our dynamical definition, the transition scale $L_t$ is given by the vertical dashed lines where $\text{KE}_{\text{bal}} = \text{KE}_{\text{unb}}$. Figure 4 shows the global $L_t$ distribution using the dynamical delineation method described above. Areas where $L_t$ exceeds 500 km are blanked out. In accordance with the shipboard ADCP data results observed along $137^\circ$E in the northwestern Pacific (Qiu et al. 2017), $L_t$ is short, $<20$ km, in the western boundary current Kuroshio region south of Japan. It increases to $\sim 50$ km in the weakly baroclinically unstable STCC band of ![Fig. 3. Horizontal wavenumber spectra of the surface eddy kinetic energy of balanced (thick black lines) and unbalanced (thin black lines) motions in the $500 \times 500$ km box centered on (a) $37^\circ$N, $164^\circ$E, (b) $21^\circ$N, $164^\circ$E, (c) $9^\circ$N, $164^\circ$E, and (d) $7^\circ$S, $164^\circ$E of the Pacific Ocean. Black dashed lines denote the $k_h^{-3}$ reference spectra and vertical gray dashed lines denote the transition scale $L_t$.](image-url) The $L_t$ value exceeds 250 km along the dynamically stable North Equatorial Current band of 9°–14°N. In the North Equatorial Countercurrent (NECC) band of 2°–9°N, $L_t$ decreases to ~200 km. Notice the $L_t$ value in the NECC band is larger than that inferred from the shipboard ADCP measurements (~80 km). This difference could be because the 1-yr llc4320 simulation is too short to account for the dominant interannual variability of the NECC, which was captured in the long-term shipboard ADCP data (Qiu and Joyce 1992; Chen et al. 2016). These results in the northwestern Pacific are quite representative for the rest of the global ocean. The $L_t$ values smaller than 20 km can be seen in all other western boundary current regions: the Kuroshio Extension, Gulf Stream, Agulhas Current, and Brazil–Malvinas Confluence. One exception is in the East Australian Current (EAC) region, which will be commented on below. Another region with small $L_t$ is along the Antarctic Circumpolar Current (ACC) in the Southern Ocean, with the exceptions where prominent bottom topographic features exist, for example, the Kerguelen Plateau near 70°E, the East Scotia Basin east of the Drake Passage, and the Spiess Seamount near the southern tip of the Mid-Atlantic Ridge. In the Northern Hemisphere’s temperate latitudes of 15°–30°N, $L_t$ falls generally in the 50–100-km range. The corresponding latitudes in the Southern Hemisphere tend to have $L_t$ in the larger O(150) km range. In the tropics equatorward of 15°, the $L_t$ values often exceed 200 km with the unbalanced motion KE overwhelming the balanced motion KE. In the high latitudes, one area where $L_t$ exceeds 200 km is in the Alaskan Gyre, where the balanced oceanic mesoscale eddy variability is extremely weak (recall Fig. 1). That $L_t$ is small in the western boundary current and ACC regions is not surprising because these are the regions in the World Ocean known for their large mesoscale eddy variability (e.g., Fu et al. 2010; Morrow and Le Traon 2012). Indeed, Fig. 5a shows the global map of the balanced motion KE integrated over the wavenumber space, and it exhibits a spatial distribution very similar to that of the mesoscale EKE map in Fig. 1a. It is, however, important to note that the level of mesoscale eddy variability is not the sole determinant for $L_t$. As shown in Fig. 5b, the wavenumber-integrated unbalanced motion KE level is similarly geographically nonuniform. It is much higher in regions with prominent bottom topographic features, like the Philippine Sea in the northwestern Pacific; the Aleutian Islands in the subarctic North Pacific; the Solomon, Coral, and Tasman Seas in the southwestern Pacific; the Tuamoto Archipelago in the central South Pacific; northeast of Madagascar in the Indian Ocean; and the continental slopes off the northeast coast of United States. Many of these locations, not coincidently, correspond to the major generation sites of internal tides in the World Ocean (Ray and Zaron 2016; Zhao et al. 2016; and references therein). In fact, it is this enhanced KE level associated with the unbalanced motions that is responsible for the elevated $L_t$ values at $\sim 150$ km in the Coral and Tasman Seas in Fig. 4, albeit the presence of the western boundary current EAC in the region. Likewise, the abyssal seamount and midocean ridge–enhanced unbalanced motions are responsible for the spatially dependent $L_t$ modulations along the ACC path in the Southern Ocean. 4. Seasonal variations in $L_t$ There exists increasing evidence in recent years that near-surface meso- and submesoscale variability in the 10–100-km range has a distinct annual cycle relating to the occurrence of mixed layer instability. Such evidence emerges from both in situ measurements in different parts of the World Ocean (e.g., Callies et al. 2015; Buckingham et al. 2016; Thompson et al. 2016; Qiu et al. 2017) and high-resolution ocean general circulation model simulations (e.g., Mensa et al. 2013; Sasaki et al. 2014; Qiu et al. 2014). Since this 10–100-km range overlaps extensively with the $L_t$ values obtained in the preceding section, it is natural to inquire if our above-defined transition scale $L_t$ is influenced by the seasonally modulating meso- and submesoscale variability. Our interest in the seasonal $L_t$ changes is further motivated by a recent study by Rocha et al. (2016b), who found that the unbalanced motion kinetic energy in the Kuroshio Extension region in the MITgcm llc4320 exhibited a seasonal maximum in summer, opposite to that of the balanced motion kinetic energy. To examine the seasonal changes in $L_t$, we define winter (summer) as February–April (August–October) and evaluate $L_t$ according to Eqs. (2) and (3) with the year-long hourly ($u$, $v$) data replaced by the seasonal ones (Figs. 6a,b). While the overall geographical dependence of the seasonal $L_t$ values is similar to the annual-mean pattern shown in Fig. 4, consistent changes with larger (smaller) $L_t$ values in the summer (winter) hemisphere are visually identifiable in Fig. 6. To better quantify the seasonal difference, we plot in Fig. 7 the $L_t$ difference of summer [August–October (ASO)] minus winter [February–April (FMA)]. In agreement with the visual changes seen between Figs. 6a and 6b, the ASO − FMA $L_t$ is by and large positive in the Northern Hemisphere (NH) and negative in the Southern Hemisphere (SH). Notice that the differential $L_t$ values are in the 50–150-km range in much of the off-equatorial ocean, and this range is on par with the magnitude of the annual-mean $L_t$ values presented in Fig. 4. An interesting exception to the SH’s general negative ASO − FMA $L_t$ occurs in the Pacific and Indian sectors of the Southern Ocean where the SH winter-minus-summer $L_t$ is small but remains positive. To clarify the cause responsible for this regional exception, we evaluate the ASO − FMA balanced and unbalanced motion KE levels in the wavelength range $< 100$ km of our interest (Figs. 8a,b). Because of the prevalence of winter mixed layer instability, the balanced motion KE level in ASO is clearly lower (higher) than in FMA in the NH (SH) oceans. This is no exception in the Pacific and Indian sectors of the Southern Ocean. For the unbalanced motion ASO − FMA KE level, Fig. 8b reveals that while it is overall positive in the NH and negative in the SH, the differential KE level remains weakly positive in the Pacific and Indian sectors of the Southern Ocean. In other words, it is the lack of summer enhancement by the unbalanced motion KE that causes ASO − FMA $L_t$ to be weakly positive in the Pacific and Indian sectors of the Southern Ocean. In their study of submesoscale seasonality in the Kuroshio Extension region, Rocha et al. (2016b) argued that the enhancement in the unbalanced motion KE in summer is due to the shoaling of mixed layer and strengthening of upper-ocean stratification. Both of these effects work to trap the inertia–gravity waves to the shallow surface ocean, enhancing the unbalanced motion’s projection onto the mixed layer (D’Asaro 1978). An inspection of the seasonal mixed layer depth changes in llc4320 reveals that the summer (FMA) mixed layer along the path of ACC (Fig. 9a) extends to below 100 m and this is particularly true in the Pacific and Indian Ocean sectors where the mixed layer can reach to deeper than 200 m. This 100–200-m mixed layer depth in the summer ACC should be contrasted to the 20-m mixed layer depth value observed typically in the summer NH oceans (see Fig. 9b) or the rest of the summer SH oceans. It is this deep summer mixed layer that is likely to be responsible for the ASO – FMA unbalanced motion KE to remain positive along the ACC shown in Fig. 8b. It is important to emphasize that the seasonal difference in the unbalanced motion KE relating to the summer trapping to within the surface mixed layer does not penetrate deep into the subsurface ocean. At the main thermocline depth of 500 m, for example, the ASO – FMA unbalanced motion KE (Fig. 10b) shows an oppositely signed distribution to that of the surface map (cf. Fig. 8b; note that the color scales are different between Figs. 8 and 10 because of the shallower depth scales associated with the submesoscale flows). Below the surface mixed layer, the wintertime unbalanced motion KE exceeds that in summer because of the enhanced surface wind forcing that elevates the KE level of the wind-induced superinertial wave motions (e.g., Alford et al. 2016). For the ASO – FMA balanced motion KE with scales < 100 km at the 500-m depth, Fig. 10a reveals that the hemispheric contrast that exists in the surface layer (recall Fig. 8a) becomes less distinctive. The ASO – FMA difference shown in Fig. 10a is spatially patchy, although the general tendency for the wintertime balanced motion KE to surpass that in summer is still discernible. In concluding this section, we plot in Fig. 11 the cumulative probability density function (PDF) distribution for $L_t$ in the NH and SH winter as a function of global ocean latitude. Taking the thick black lines as an example, it is clear from Fig. 11 that 80% of $L_t$ falls below 20 km in most of the NH oceans between 25° and 45°N and in all of the SH oceans south of 25°S. That the wintertime $L_t$ is shorter than 20 km in most of the extratropical NH and SH oceans indicates that the entanglement between balanced and unbalanced motions will likely pose less of a challenge for the SWOT mission in these locations to detect the balanced submesoscale features in winter. --- 2 Similar seasonally varying spatial patterns of the mixed layer depth can be found in the mixed layer depth climatology based on in situ measurements; see, for example, Fig. 5 in de Boyer Montégut et al. (2004). 5. SSH variance-based $L_{SSH}$ In the preceding sections, we have explored the global distribution of $L_t$ based on kinetic energy equality between the balanced and unbalanced motions. From a practical point of view, $L_t$ thus derived could be regarded as the length scale below which surface circulation inferred geostrophically from the SSH gradient becomes unreliable. With the high-resolution SSH information from the planned SWOT mission, it is instructive to also evaluate the transition scale that is based on the SSH variance equality between the balanced and unbalanced motions. To differentiate this transition scale based on the SSH variance equality from the $L_t$ defined in section 3, we denote hereafter the SSH variance-based $L_t$ as $L_{SSH}$. To evaluate $L_{SSH}$ from the hourly output of llc4320, we adopt the same dynamical delineation method detailed in section 3 and replace the KE spectra by the SSH variance spectra in Eqs. (2)–(3). Figure 12a shows the distribution of $L_{SSH}$ calculated from the year-long llc4320 output. Geographically, $L_{SSH}$ exhibits a spatial pattern very similar to that of the KE-based $L_t$ shown in Fig. 4. Like for the balanced and unbalanced motion kinetic energy levels, the wavenumber-integrated SSH variance associated with the balanced and unbalanced motions are similarly spatially inhomogeneous (figures not shown). By and large, $L_{SSH}$ has a larger value than $L_t$ as compared in Fig. 12b and the general trend is such that their difference, $L_{SSH} - L_t$, decreases progressively from the equator toward higher latitudes. It is of interest to consider here why $L_{SSH}$ exceeds in general $L_t$ and what contributes to the diminishing difference, $L_{SSH} - L_t$, from the equator toward higher latitudes. For simplicity, let us consider a linearized shallow-water ocean in which surface velocity $u$ and $v$ and SSH $\eta$ are governed by (Gill 1982) $$-i\omega u - f v = -ig k \eta,$$ $$-i\omega v + f u = -ig l \eta,$$ $$-i\omega \eta + iH(\eta u + lv) = 0,$$ where $(u, v, \eta) = (\hat{u}, \hat{v}, \hat{\eta}) \exp(ikx + ily - i\omega t)$, and $H$ denotes the water depth (or equivalent depth for a baroclinic mode in the stratified ocean). Rearranging Eqs. (4)–(6), we obtain $$\hat{u} = g(\omega k + ilf) \hat{\eta}(\omega^2 - f^2),$$ and (7) $$\hat{v} = g(\omega l - ikf) \hat{\eta}(\omega^2 - f^2),$$ and the wavenumber–frequency spectra for KE and SSH variance $\hat{E}(kh, \omega)$ and $\hat{H}(kh, \omega)$ are in this case related through $$\hat{E}(kh, \omega) = \frac{g^2 k^2}{2} \frac{\omega^2 + f^2}{(\omega^2 - f^2)^2} \hat{H}(kh, \omega),$$ where $k_h^2 = k^2 + l^2$. For the balanced motion, $\omega \ll f$, and its KE spectrum defined in Eq. (2) can be approximated by $$\text{KE}_{\text{bal}}(k_h) = \int_{\omega_f}^{\omega_b} \frac{g^2 k^2}{2} \frac{\omega^2 + f^2}{(\omega^2 - f^2)^2} \hat{H}(kh, \omega) d\omega \approx \frac{g^2 k^2}{2f^2} \text{HV}_{\text{bal}}(k_h),$$ where $\text{HV}_{\text{bal}}(k_h)$ denotes the SSH variance spectrum associated with the balanced motion. The KE spectral slope in Eq. (10) is shallower than the SSH variance spectral slope by $k_h^2$ has been extensively used in previous studies of mesoscale eddy variability based on satellite altimeter data (e.g., Stammer 1997). For the unbalanced motion, combining Eqs. (3) and (9) leads to $$\text{KE}_{\text{unb}}(k_h) = \int_{\omega_f}^{\omega_b} \frac{g^2 k^2}{2f^2} \frac{\omega^2 |f|^2 + 1}{(\omega^2 |f|^2 - 1)^2} \hat{H}(kh, \omega) d\omega.$$ As demonstrated in Fig. 2, the unbalanced motion KE resides largely in the near-inertial, diurnal/semidiurnal tide and discrete IGW bands. Since the near-inertial motions have weak projections onto SSH (e.g., Alford et al. 2016), contributions to the RHS integration in Eq. (11) come mostly from the tidal and IGW motions. If $\hat{H}(kh, \omega)$ is assumed to be dominated by the tidal or IGW motion with a particular frequency $\omega_0$, we may approximate $\hat{H}(kh, \omega) = \hat{H}(kh, \omega_0) \delta(\omega - \omega_0)$, where $\delta$ is the Dirac delta function. In this case, Eq. (11) becomes $$\text{KE}_{\text{unb}}(k_h) = \frac{g^2 k^2}{2f^2} \frac{\omega^2 |f|^2 + 1}{(\omega^2 |f|^2 - 1)^2} \text{HV}_{\text{unb}}(k_h),$$ where $I = (\omega_0^2 |f|^2 + 1)/(\omega_0^2 |f|^2 - 1)^2$. From Eq. (13), it is clear that the difference between $L_t$ and $L_t^{\text{SSH}}$ depends on the magnitude of $I$. If $I > 1$, $L_t$ will surpass $L_t^{\text{SSH}}$ and, if $I < 1$, $L_t^{\text{SSH}}$ will exceed $L_t$. For the semidiurnal tides, $I$ is spectra have similar contrast, the unbalanced motion KE and SSH variance versa. For a fixed mode where cn MARCH 2018 Q I U E T A L . 601 respect to spectral slope; recall Eq.(10) and compare the spectra SSH variance spectral slope is steeper than the KE Fig. 7. One reason for this is that the balanced motion slopes for KE and SSH variance inFig. 15 at a repre- titudes. These tidal effects are consistent qualitatively to that for FMA, and its global pattern is spatially very similar tidands across the latitudinal bands of the World Ocean. As inFig. 2, cn (n = 1 to 10) are calculated based on the WOA2013 climatological temperature–salinity profiles (Locarnini et al. 2013; Zweng et al. 2013). Unlike the tidal effect noted above, the I = 1 threshold for IGWs not only depends on latitude but also on the wavenumber. Specifically, I can remain less than unity in high-latitude oceans when kh is large in the 10–100-km wavelength range of our interest. It is in fact the contributions from the low-mode IGWs that keep LtSSH > Lt in some of the high-latitude areas seen in Fig. 12b. Like the seasonal changes in Lt, the SSH variance-based LtSSH is also subject to distinct seasonal modulations. Figure 14 shows the LtSSH difference between ASO and FMA, and its global pattern is spatially very similar to that for Lt shown in Fig. 7. The seasonal amplitude in LtSSH, on the other hand, is about half that obtained in Fig. 7. One reason for this is that the balanced motion SSH variance spectral slope is steeper than the KE spectral slope; recall Eq. (10) and compare the spectra slopes for KE and SSH variance in Fig. 15 at a representa- tive site of 37°N and 164°E in the North Pacific. In contrast, the unbalanced motion KE and SSH variance spectra have similar kh slopes (cf. dashed lines in Fig. 15). This renders the seasonally varying crossings by balanced and unbalanced motion SSH variance spectra more restricted in the kh space than those by balanced and unbalanced motion KE spectra. 6. Discussion and summary We have in this study explored geographical and seasonal variations in the transition scale at which the geostrophically balanced motion loses its dominance over the unbalanced wave motions. As the metric for the transition scale, we adopted Lt defined by the wave-length that has equal balanced and unbalanced motion KE spectral densities. By analyzing the hourly output from the 1/48th horizontal resolution MITgcm llc4320, we found that Lt is geographically highly inhomogeneous. Broadly speaking, Lt falls below 40 km in the western boundary current and ACC regions and increases to 40–100 km in the vast subtropical and subpolar world oceans. An exception to the latter case is in the Alaskan Gyre where Lt can exceed 200 km. In the tropical oceans equatorward of 20° latitudes, Lt is found, in general, to be larger than 150 km. These llc4320-derived, latitude-dependent Lt values are, by and large, consistent with our recent estimates based on the repeat shipboard ADCP measurements along 137°E in the northwestern Pacific Ocean (Qiu et al. 2017). On a regional scale, the Lt value depends not only on the local level of mesoscale eddy variability, but also on the energy level set by the unbalanced motions consisting of near-inertial flows, internal tides, and inertia–gravity waves. The unbalanced motion energy level is spatially nonuniform, and high values are commonly detected where prominent bathymetric features exist. Examples of effects on Lt by enhanced unbalanced motions include the East Australian Current region where Lt reaches 100 km (rather than 20 km as in other western boundary current regions) and along the ACC path where increased Lt values are found to be collocated with the major topographic features in the Southern Ocean. The energy levels of both the balanced and unbalanced motions modulate seasonally and, as a result, they can alter the \( L_t \) value constructively. In winter, small-scale balanced motions are energized because of the ubiquitous occurrence of mixed layer instability. Shoaling of the mixed layer and increasing of density jump at the mixed layer base in summer, on the other hand, works to trap and elevate the surface unbalanced motion kinetic energy (Rocha et al. 2016b). The combined effect of these seasonal kinetic energy changes results in a seasonal contrast in \( L_t \) that can typically reach >100 km in significant parts of the global ocean. One important exception to this \( L_t \) change caused constructively by the seasonally varying balanced and unbalanced motions is seen in the Pacific and Indian sectors of the Southern Ocean. In these sectors, the regional mixed layer in summer remains deep, failing as a result to trap effectively the unbalanced motion kinetic energy to within the shallow surface layer. In addition to the metric \( L_t \) based on KE equality, we have in this study also examined \( L_{SSH}^{SS} \) defined by the wavelength at which balanced and unbalanced motions have equal SSH variance spectral densities. The \( L_{SSH}^{SS} \) shows similar geographical and seasonal patterns as those of \( L_t \), highlighting the common dynamics controlling the spatial and temporal variations between these two transition-scale metrics. While exhibiting similar patterns, the \( L_{SSH}^{SS} \) values are in general larger than \( L_t \), especially in low-latitude oceans. The difference \( L_{SSH}^{SS} - L_t \) tends to diminish toward the high-latitude oceans, where \( L_{SSH}^{SS} \) may become shorter than \( L_t \). The reason for this tendency is that in the wavenumber space, the KE and SSH variance spectra are functionally related differently for the balanced and unbalanced motions. While the balanced motions between the two are proportional to \( k^2 \), the unbalanced motions are connected via convolutions that are sensitive functions of latitude. Since \( L_t \) signifies the transition scale below which the SSH data may no longer be used to accurately infer the geostrophically balanced flows, our findings about its geographical and seasonal variations are highly relevant for the forthcoming SWOT mission. With the 15-km spectral resolution expected for the SWOT mission (Fu and Ubelmann 2014), unbalanced motion signals are likely to pose little problems for detecting the balanced submesoscale flows in the mesoscale-rich regions like the ACC and the western boundary currents in the North Pacific, North Atlantic, South Atlantic, and south Indian Oceans. For the East Australian Current and in the regions of moderate mesoscale activities (e.g., the Subtropical Countercurrent bands in temperate latitudes), caution is likely warranted in diagnosing the surface geostrophic flows in the 50–100-km range. It is worth emphasizing that the annual-mean $L_t$ values noted above can decrease significantly in winter because the seasonal balanced and unbalanced motion KE levels fluctuate out of phase, shortening $L_t$ constructively in winter. Indeed, our analysis revealed that 80% of the NH oceans between 25° and 45°N and all of the SH oceans south of 25°S will have $L_t$ shorter than 20 km during the winter season, including the EAC and the Subtropical Countercurrent bands cautioned above. Since winter is the season when the balanced submesoscale motions prevail, this implies that the SWOT-measured SSH signals can be used potentially to explore the wintertime submesoscale variability down to the 15–20-km range in a significant part of the extratropical world oceans. The serious challenge for the SWOT mission to capture the small-scale geostrophically balanced motion will be in the tropical oceans within ±20° latitudes and in the Alaskan Gyre, where $L_t$ commonly exceeds 150 km in all seasons. This challenge stems from the fact that these regions have a high unbalanced motion KE level as compared to the balanced motion. One important source behind the high unbalanced motion KE is the internal tides generated by the interaction of barotropical tides with bottom topography. It is important to note that a significant portion of the low-mode internal tides have been known to exhibit phase stability, or coherence, in their SSH expressions (e.g., Ray and Mitchum 1996). By analyzing the internal tidal signals from the 17-yr combined record of TOPEX/Poseidon and Jason altimeters, Ray and Zaron (2011) estimated that the stationary variance is generally 75% or more of the average variance of mode-1 internal tides. More recent numerical modeling and data analysis studies by Shriver et al. (2014) and Zaron (2017) have revealed that the fraction explained by the stationary internal tides can be highly spatially inhomogeneous. In the context for $L_t$ determination, it is obvious that any removal of internal tidal signals that are stationary and predictable will result in a reduction in the $L_t$ value. A judicious separation between the stationary and nonstationary internal tides requires multiyear in situ measurements or numerical model output. Rather than pursuing this separation based on the year-long llc4320 output, we attempt to quantify the reduction in $L_t$ by assuming that a fraction of the llc4320-modeled diurnal and semidiurnal internal tidal signals are stationary and could be, as a result, removed. Specifically, we follow Zaron (2017, his Fig. 9) and assume that the variance fraction explained by the stationary internal tides has a simple latitude-dependent form: $$\alpha(y) = \begin{cases} 0.9 & |y| < 50^\circ \\ 0.9 - 0.012|y| & |y| \geq 50^\circ \end{cases}$$ where $y$ is the latitude in degrees. Using this form, we subjectively reduced the wavenumber KE spectra (recall Fig. 2) by $1 - \alpha(y)$ in the diurnal and semidiurnal frequency bands over the background continuum and reevaluate $KE_{\text{unb}}(k_b)$ in Eq. (3). Here, we define the diurnal (semidiurnal) frequency band as bounded by $\omega = 1/27.0–1/23.0$ (1/13.5–1/11.5) cph and the background continuum by linearly interpolating the frequency spectra within these chosen bounds by neighboring spectral values. Figure 16a shows the annual-mean $L_t$ distribution based on the newly evaluated $KE_{\text{unb}}(k_b)$, while its difference from the $L_t$ values shown in Fig. 4 is presented in Fig. 16b. From Fig. 16b, it is clear that removal of the stationary internal tidal signals can reduce $L_t$ by 50–100 km in many regions of the World Ocean; significant reduction in $L_t$ is seen in the Alaskan Gyre, the northwestern tropical Pacific, and the broad tropical and subtropical SH oceans. Because of the smaller fraction of the stationary internal tides, the reduction in $L_t$ is modest, generally less than 50 km, within the ±10° equatorial band. For completeness, we present the same analysis results in Fig. 17 with respect to $L_t^{SSH}$. Although having smaller amplitude when compared to $L_t$, the reduction in $L_t^{SSH}$ caused by the removal of stationary internal tidal signals exhibits a similarly geographical pattern. The results shown in Figs. 16 and 17 are based on our current knowledge about the distributions of the stationary internal tides. Because of the background changes in ocean stratification, currents, and mesoscale eddies, isolating and removing the stationary internal tidal signals from the SWOT SSH measurements will be a formidable endeavor. Nevertheless, we believe the results of Figs. 16 and 17 suggest that this endeavor is critical and should be pursued in order to improve detection of the balanced submesoscale signals and maximize the science returns by the SWOT mission. Acknowledgments. We thank Rosemary Morrow, Clement Ubelmann, and Ed Zaron for insightful discussions. Constructive comments made by two anonymous reviewers helped improve an early version of the manuscript. B. Q. and S. C. acknowledge support from NASA SWOT and OSTST missions (NNX16AH66G and NNX17AH33G). P. K. acknowledges the support of the Agence Nationale pour la Recherche [ANR-10-LABX-19-01 (LabexMER)] and of the SWOT project (JPL, NASA), J. W., H. T., L. F., and D. M.’s research presented in this paper was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. They acknowledge support from the SWOT projects. REFERENCES
Possibility, Novelty, and Creativity Alexander Haitos Lehigh University Follow this and additional works at: http://commons.pacificu.edu/rescogitans Recommended Citation Possibility, Novelty, and Creativity Alexander Haitos Lehigh University Published online: 26 July 2010 © Alexander Haitos 2010 The Problem Genuine novelty is the introduction and creation of new things, relations, and affections in the world. Human experience constantly confronts us with novelty, in surprising, intimate ways (spotting new freckles, a great cup of hot chocolate, budding flowers), and in more time-extended, sweeping ways (invention of the automobile, the Little Ice Age, the development of *homo sapiens*). And yet things are the same. The novel always contains what has already been as a component, but with some modification. Generically, all novelty is the outcome of some creative act, and all creative acts beget some novelty. Apart from this, the concept of novelty is not homogenous. There can be novel *items* – individual and unique things. There can be novel *kinds*: new sorts of things or states of affairs, new types of events. There can be novel problems and questions and concepts. All novelty involves a *measure* of unpredictability and a *measure* of breaking from the status quo. And novelty is a pervasive element of human experience. I want to take this aspect of human experience seriously when doing metaphysics; I do not want to make the world of human experience secondary to some ineffable realm. Because our experience is an aspect of the real world, an account of novelty must acknowledge that the novel things that emerge in the course of events are “genuine.” That is, they are metaphysically significant and ontologically real. I want to construct a metaphysic that accommodates pervasive change and novelty, one that accommodates radical novelty. This is, however, a drastic change from much contemporary metaphysical work. Often, the way change is dealt with metaphysically renders our most intimate interactions and feelings an unimportant component of reality (if it is a component at all). Thus the reworking of many fundamental notions is required in order to make... sense of the ideas of ‘change’ and ‘novelty.’ One of these notions is ‘possibility.’ Commonly held notions of possibility, such as an existence-less form (a “possible object” – a plaid apple, for example), or possibility as a rearrangement of the elements of actuality (taking what actually exists and putting it in new combinations – horse + horn = unicorn), drain all significance from the notion of novelty. In this paper, I attempt to revise our notion of possibility using Bergson and Whitehead by creating a picture that does not entail “possible objects,” but allows for a creative actuality and radical novelty. This modified view of possibility will provide a basis for understanding higher and more complex and coordinated forms of novelty. **Possible as Less than the Actual** A common view of possibility takes the possible to be less than the actual. That is, the possible has the same detailed form as the actual, but is lacking a crucial element of concreteness – existence. These existence-less forms are *possibilia*, or possible objects. For example, if it is possible for me to get my hair cut a certain way, that possible haircut remains in its peculiar state of ideal being until I do in fact get my hair cut that way. Then the possibility becomes an actuality. There is a passage from the possible to the actual; everything actual was preceded by possibility. Existence sweeps forward and fills in forms. Because possibility is less than actuality, it is thus in some sense prior to actuality, and thus there exists the capability, in principle, to know and examine possibilities long before they become actualities. Because novel features of new events are, in principle, knowable beforehand, the features are not novel-in-themselves. If this is the case, what is novelty? Novelty in actuality could only be the actualization itself. For if the form precedes its realization, what is novel about the realization other than the fact that it is now actual? Now, nothing is wrong with including the newness of existence as an aspect of novelty, but merely adding existence to a form does not capture the idea of ‘genuine’ novelty. If the strange stick figure I drew this morning is novel solely in virtue of its existence, it is novel in exactly the same way everything in the world is novel. Both my drawing and the invention of the digital camera would, on this view, be novel in the same way: they both now exist, and the fact of existence is the only fact of novelty. If all novel things are novel in the same way, there is nothing really novel about them; the novelty of uniqueness immediately grows stale. Novelty becomes a stand-in for existence, and thus meaningless. Thus if possibility is really less than the actual and simply filled in with ‘existence’, novelty is a sterile concept. Something more is meant, though, by novelty. The novelty of something is more than its *mere* existence; it is also fresh. There is the air of ‘nothing has been quite like this’ – it is the novelty of *vibrancy*. Bare existence does not capture this. The concreteness of *this particular occurrence (existence) in the world* must be appealed to. But to get there, this notion of possibility must be rejected. The Combinatorial View of Possibility Combinatorialism is a theory of possibility that views the possible as less than the actual, but does not think possibilities are ideally preexistent. It takes what is possible to be rearrangements of what is actual. If what is actual (real) in the world can be combined or recombined in some way—any way—that recombination is a possibility. There can be novel combinations, combinations that have not ever had an instantiation. Novel combinations add more than mere existence; through the newness of arrangement they add ‘nothing is quite like this.’ In fact, every moment and alteration of objects and events heralds a novel combination. A particular handbag is the first and only handbag that is that particular combination of elements which is just like it is. A particular atom that loses an electron but gains another is the first and only atom just like it is. Novel combinations abound in the world. Thus a combinatorial view of possibility seems to give us a doctrine of pervasive genuine novelty, or radical novelty; new (unique) things and new vibrancies are widespread. Though it seems to be leaning towards explaining radical novelty, there are some shortfalls of combinatorialism. Because possibility is defined in terms of actuality, it is not possible for there to be new actuality. Indeed, on this view, actuality takes on many of the characteristics of Parmenidean being: what is actual now is what was actual before and what will be actual later. Only arrangement changes. This denies full actuality to things-in-combination, like desks and apples, which constitute the entirety of our experienced lives. Thus possibility is still less than actuality, and the critiques of ideally preexistent possibility (predictability, immediate staleness, etc.) will apply here as well, though perhaps in slightly modified forms. In addition, an aspect of a strong doctrine of metaphysical novelty (radical novelty) is that new actualities come into existence; ontology itself changes. Combinatorial possibility holds there is some ontological level that does not change, but merely shifts, and this level takes on the name Actuality. The denizens of this level are exempt from novelty. Novelty only appears at the levels in which the elements of actuality are rearranged. Combinatorial possibility gives us a notion of novelty for experience, but at the expense of the reality of our experienced world, and this makes novelty superficial. For a deep radical novelty we must find a different model of possibility, keeping in mind the insights of the combinatorial view. Possible as More than the Actual If possibility were to have ideal form preceding reality, the possible would have been there from all time, awaiting its realization, allowing itself to be foreseen, and thus extinguishing any life from the notion of novelty. Henri Bergson believes that speaking of possibility in this way, as a form without concrete existence, involves a fundamental conflation of two distinct senses of ‘possibility.’ In one sense, possibility is less than and precedes actuality only in the sense that some event is ‘not impossible.’ 2155-4838 | commons.pacificu.edu/rescogitans Something is not impossible if there is no contradiction in it occurring. This is a negative statement and attributes no definite form to what is possible, but merely gives a condition for realization. Though it falls short of accommodating novelty, the combinatorial theory of possibility gives an insightful image of what we can conceptualize as ‘non-impossibilities.’ Possibility as an ideal form, on the other hand, actually presupposes actuality and adds to it; it is actuality in its every detail plus the mental act recognizing it. As such, it cannot come prior to actuality. By conflating possibility as ‘not impossible’ and possibility as ‘ideal form or possibilia’, one can arrive at the conclusion that possibilia have all the descriptive characteristics of actuality and can be predicted or known before occurring. Think for a moment about Hamlet. For that exact play to be possible, Shakespeare himself is needed in the exact circumstances under which the play was indeed written. The details are of supreme importance. For Hamlet to have taken on the character it did, anyone writing it must have thought, felt, and experienced what Shakespeare did, that is, Shakespeare and his society are necessary, as are the conditions for that society, and so on. Every bit of the actuality of Hamlet and the actuality it presupposes must be contained within the ideal form of Hamlet. Thus the possibility of Hamlet, taken as an ideal possibility, requires the existence of Hamlet. To characterize Hamlet in all its detail would be to invent it. If such a characterization existed prior to Shakespeare’s writing Hamlet, Shakespeare did not really invent Hamlet. The novelty of Hamlet is lost, as is Shakespeare’s creative genius. Taken as an ‘ideal’ characterization, possibility implies the corresponding actuality and, in addition, the mental act which exposes this particular actuality as having been possible throughout the past. Thus to preserve novelty, we must hold that the possible precedes the actual only if possible is taken to mean ‘not impossible.’ Possibility as an ideal form occurs retroactively to actuality. This reworking of the idea of possibility has created space for an account of novelty. The novel still has conditions, however. The first is that what is novel is, at the time of its actualization, not impossible; that is, the actuality of what does exist cannot conspire against the coming into being of the novel thing. So it is necessary for novelty that it be not impossible, but is it sufficient? At first blush, I think not. But in a deeper sense, it is. More must be extracted from the notion of ‘not impossible.’ **Conditions of Novelty** The notion of radical novelty, if true, entails that novelty is continuously produced throughout the universe; every new moment of existence is radically novel – an extension of the past, mixed with new and unforeseen flavors. But there is an order underlying the pulse of the universe, though it is an incomplete order. If what is radically new is, prior to its actualization, something simply ‘not impossible’, what carries forward the recognizable order into the future? That is, if every moment of existence contains a radically new element and there are no conditions on this element other than its non-impossibility, what keeps the undeniable pattern of events from swerving wildly and completely? Something being ‘not impossible’ assures a limited accord with the past. On the face of it (that is, taking into account only contemporaneous occasions of actuality), the sudden and rapid degeneration of a hunk of gold into powder doesn’t seem impossible – there are no physical impediments, and so on. But this fails to take into account the propagation of modes of order throughout successive occasions of existence. The weight of the past bears on the possibility (non-impossibility) of the future. For this to be the case, there is required a definite transmission of affective force from present existence to future existence; the basic character of the future is the character given by the present, and thus the past. The modifications to this character are a result of the introduction of radically novel elements. But the modifications must not be excluded by the current characteristics dominant in actuality, including modifications dominant for a stretch of actuality. An objection can be raised: you have committed yourself to saying that novelty issues from nothingness (ex nihilo), and this is absurd, even if it is correct that the weight of actuality provides ‘exclusion’ conditions on novelty. Novelty obviously cannot come from ‘the weight of actuality’; novelty is supposed to introduce elements foreign to actuality into it, and actuality cannot provide what it does not have. Novelty also cannot derive from a ‘formed’ possibility, as it exists only after and in virtue of the fullness of actuality. But if what is actual cannot beget what is novel, and if possibility in any ‘strong’ or ‘ideal’ sense is a consequent, not an antecedent, of actuality, then novelty must come from nothing. It does not matter if actuality places limits or conditions on what can emerge as novel – something is coming from nothing. And if it were coming from nothing, the effectiveness of actuality in providing limits would seem to be dubious at best. But then there would be nothing stopping the novel elements from overturning any order at any time, and we simply do not observe this. If you want to hold a strong sense of novelty, it seems like it cannot come from “nothing.” But to avoid this, recourse to some ‘ideally pre-existent’ possibility is needed. But this, by your own admission, destroys novelty. The heart of the objection, it seems to me, is this: novelty, or what is called novelty, seems to require some measure of conformity to the past. But how can actuality place limits on nothing? Even if something could come from nothing, there is no reason why limits or conditions could be placed on such a something – it is generated completely external to actuality and its influence. Thus novelty ex nihilo would have no regard for any order, and this is clearly not something that can be said of everything, possibly anything, ‘radical novelty’ is intended to apply to. This objection may seem intractable, but it turns on muddled notion of ‘nothing’. By clarifying the notion of ‘nothing’, the seeming impossibility of the emergence of novelty ex nihilo and the influence of actuality on such ‘nothingness’ will vanish. **Nothing as Everything** Similar to the confusion between two distinct senses of ‘possibility’, there is a confusion between two distinct senses of ‘nothing.’ The first, and most basic, way of using nothing signifies it as the absence of what we are seeking. The other sense of ‘nothing’ means, roughly, absolute emptiness. But we do not experience absolute emptiness. There are always limitations and contours. Emptiness, as we experience it, is a substitution of one thing for another (a ‘ring’ for ‘some air’), with the suppression of one end of the substitution. This is the only way we mean emptiness. Absolute emptiness is a universal substitution and suppression of all the elements of our experience. As Henri Bergson put it: > In other words, this so-called representation of absolute emptiness is, in reality, that of universal fullness in a mind which leaps indefinitely from part to part, with the fixed resolution never to consider anything but the emptiness of its dissatisfaction instead of the fullness of things. All of which amounts to saying that the idea of Nothing, when it is not that of a single word, implies as much matter as the idea of All, with, in addition, an operation of thought. When considering emptiness, we seek nothing and are satisfied by nothing, turning a blind eye to everything. We think we know what absolute emptiness could be, but ignore that simply through considering we consider *something*, thus ignoring the “fullness of things” which confronts us. Thus, like the notion of possibility, the notion of nothingness itself contains the whole of actuality with the addition of a particular mode of thought. These considerations wholly alter the criticism leveled against creation ex nihilo. Creation ex nihilo is really creation ex omnibus; it is creation from *everything*. The entire universe is conspiring, in its way, to the creation of every fact of existence. But phrasing it ‘creation ex nihilo’ still bears a purpose. The most salient feature of creation which is captured by ‘nothing’ is its indeterminacy, its impenetrability to perfect foresight or complete characterization. ‘Nothing’ also captures the reach beyond actuality better than ‘everything.’ That which is indeterminate must lie beyond established fact. Thus the reach is beyond actuality. Novelty is an issue of the universe’s creative process, from which it pulls into determination new affective elements. But one cannot ‘see’ or determine precisely from whence novelty springs. Novelty is an issue from the infinitude of everything, overwhelming and yet indeterminate, so as to yield it the name *Nothing*. One could leave it here, saying that novelty is the result of the universe’s mutual determination of some indeterminacy. This would leave a vital question unanswered. Namely: What is everything such that it leaps beyond actuality into indeterminacy? By affirming indeterminacy as an aspect of everything, it is something, not nothing (which seems merely to indicate the ineffable character of the indeterminate). Leaving a description of the indeterminate as simply ‘that which is not impossible’ seems like premature mysticism. But the indeterminate is ‘that which is not impossible’, provided it is understood the right way. There is only so far one can probe the character of the genuinely indeterminate, ‘that which is not impossible.’ As a preliminary step, Alfred North Whitehead’s doctrine of Eternal Objects can be viewed as a positive partial rendering of creation ex nihilo. Such a rendering, though complex, will yield insights into novelty and possibility. The Indeterminate: Eternal Objects To best describe how eternal objects can be viewed as the indeterminate source of novelty, a better idea is needed of what an (eternal) object is. Reference to objects involves “reference to a realm of entities which transcend that immediate occasion in that they have analogous or different connections with other occasions of experience.” Thus an object is that which can recur in separate occasions of experience. What defines an object and gives it its character is the affective tone that it contributes to the overall occasion of experience. The more abstract one gets in isolating these contributions of affective tone, the broader the perceived potential connection with other occasions of experience. ‘Rug’ is more abstract and thus more broadly applicable than ‘green rug next to the desk’. This realm of abstracted objects capable of broad ingestion into occasions of experience can be termed the realm of ‘eternal objects’, or ‘ideal entities’. This realm can also be characterized as potentialities for actuality. The realm of ideal entities is infinitely large – there is nowhere actuality cannot go, that creativity cannot reach. This infinitude is the indeterminacy. It is the indeterminateness of specific realizations of these ideal entities that keep these possibilities from being ‘ideally pre-existent’ – that is, no specific arrangement of eternal objects exists prior to actualization. When something happens, it is new. How the indeterminacy accomplishes this and how the realm of ideal entities is indeterminate will soon become clearer. First, ideal entities are indeterminate due to their necessary reference beyond themselves. They are possibilities for actuality, so they necessarily refer to definite actualities. Also, they do not ingress into actuality singly; ideal entities are related to all other ideal entities based on potentiality of joined realization. The relations an ideal entity bears to other ideal entities and to occasions of actuality are parts of its essence. But so is the peculiar character of that ideal entity. The way ‘red’ stands in regard to other ideal entities and to realizations of actuality are part of its essence, as is the affective tone peculiar to it.\textsuperscript{15} Because ideal entities are infinite, one could not give an exhaustive account of the essence of ‘red.’ Into a new occasion of actuality there is always the ingression of some (hierarchical) set of ideal entities. The sets, and thus the hierarchies, are undetermined prior to ingression, that is, unformed. Formation occurs during actualization. So the realm of ideal entities is indeterminate as to what complex affective tone ingresses into occasions of experience. When Whitehead calls the realm of ideal entities “numberless”\textsuperscript{16}, he both means its membership is infinite, and also that it is indeterminate and thus uncountable and thus referable to only as a whole. That is, the realm of ideal entities is both a multiplicity and a unity. If the analogy helps, the realm of ideal entities could be thought of as a membrane with knots of affective energy. There is no definite structure to (regions of) the membrane prior to actualization. In actualization, the ideal entities are graded\textsuperscript{17} in respect to their relevance and contribution to that occasion, forming the hierarchical structure of the set of ideal entities. Thus the realm of ideal entities is a ‘something’ in everything, but is nothing until its ingression into actuality. So possibility, in the form of ideal entities, has genuine ‘universal fullness’ while retaining indeterminacy prior to actualization.\textsuperscript{18} And it is in the creation of definiteness out of infinitude – in the process of actualization – where novelty can be found. **Novelty: The Issue of Infinitude** During the process of actualization, the weight of the past and its transmission of affective character determines what is ‘not impossible’ for the new occasion. This is an initial limitation on what set of ideal entities can ingress into that occasion; there must be some conformity with the prevailing affective tone. The definite set that ingresses into the new actuality is novel; it is a novel complex affective tone, one that did not exist prior to its ingression. This novel tone interacts with the old tone, generating a third, and novel, tone at the perishing of that occasion of existence. Thus what is novel is a new affective tone of experience. From this it follows that every occasion of existence is novel: they are created in the process whereby new sets of ideal entities merge with the old; radical novelty is every moment of existence. From the infinitude of ideal entities (of possibilities), novelty is produced due to a generation of finitude from the infinite. From what exists in infinitude, a novel finite determination is created. Actuality is this finitude; its definiteness generates the individuality requisite for the agglomeration of affective experience. It has been shown that the notion of possibility, properly construed, can cohere with the doctrine of perpetual radical novelty. The above sketch of possibility may seem strange, but taking the breadth of potential novelties into account is no simple task. Regardless, the creative advance of nature does not need to be relegated to a lesser order of reality, and this is important for any attempt at a comprehensive and meaningful metaphysic. References --- 1 This paper is a fusion of my philosophical concerns and my readings of Alfred North Whitehead and Henri Bergson. Consequently, much of the paper is indebted directly and indirectly to the work of these two men. As will be noticed, some of my terminology is borrowed from these two, particularly Whitehead, and I try to give adequate definitions when appropriate. 2 I’m thinking roughly of the last fifty or sixty years in the analytic tradition, including philosophers such as W.V.O. Quine, Saul Kripke, Hillary Putnam, Roderick Chisholm, Jaegwon Kim, David Lewis, and so on, though issues concerning novelty and change have been around for much longer. 3 This characterization of possibility applies to talk about *possible worlds*. Possible worlds and the possibilia inhabiting them are just existence-less forms. Even David Lewis’s extreme realism about possible worlds fits in rather well here; in this case “exists” would simply be short for “exists in the actual world”. It would be worth discussing Lewis’s case in more detail, but that discussion is tangential to my main issue: novelty. There are different levels of ‘contradiction’, such as logical contradiction, physical contradiction, etc. These levels give a basis for determining probabilities of non-impossibilities. Bergson, “The Possible and the Real”: 230 (including the *Hamlet* example). The affective forces of an occasion of existence are those elements, if I may be circular for a moment, which are felt by consequent occasions of existence. The parts of an existence that are transmitted from past to future are literally the dominant features of the ‘experience’ of that existence. An experience is comprised of elements that have some effect, or alter the character of, the experiencer. Strictly speaking, it is components of the experience that are transferred, not the experience itself; it is the power of an element in experience that is transferred. An occasion of existence that is affected by an affective force is different than it would have been otherwise. For example, the color red can be a component of experience and it carries a certain power – a power to affect certain other occasions of experience, like when one feels oppressed or anxious when in a red room for too long. Once a moment of time has passed – once one has moved to a new moment of existence – the power of the red room is still vivid. This is one example of affective force. Or consider a glass resting on a table; throughout successive moments it continues to sit on the table because the table contributes – very literally – a force to what that glass experiences, and so it does not move downward though there are other affective forces also altering its character and behavior (gravity, for example). Basically, an affective force is something that has some effect on other actualities. It is these effects that are transmitted into the future. And it is these effects that alter and contribute to the changing and novel character of experience. The idea of affective forces is taken up more directly later in the paper. “Did you find it?”, “No.”, “Did you look in your room?”, “Yeah, there was nothing.” But obviously there was something in the room, just not what you sought. Bergson, “The Possible and the Real”: 229-30 c.f. Malebranche: “To think of nothing and not to think at all, to perceive nothing and not to perceive at all, are the same thing.” An affective tone is similar to an affective force, described earlier. The affective tone of an object or an occasion of experience is the set of affective forces it contributes to other occasions of experience. It is the method through which an object interacts with occasions of experience. An object may prevent or incite an occasion of experience to behave in a certain way, like a brownie incites one to ingest it, or a rock prevents water from flowing directly downhill. This ‘inciting’ and ‘preventing’ would all be examples of affective forces, which can sit within the affective tone of some particular object. 15 These two aspects would seem to be co-determined. 17 Gradation of ideal entities refers to the hierarchical ordering of ideal entities based on the contribution they make to the character of an occasion of experience. The more an ideal entity contributes of its character, the higher it sits in the hierarchy. This captures the idea that some ideal entities are a more salient fact in some occasions of experience than in others; some experiences are much more ‘red’ (or ‘bright’, or ‘joyous’, …) than others. 18 When one says that something is possible, such as, “I could move my cup two inches to the right,” one is not giving a definite or determined possibility. One is still giving an account, albeit a more specific account, of what is not impossible. To give a genuine definite possibility (one ‘ideally pre-existent’), one would need to give an exhaustive account of the new set of affective tones and its effects. But this is impossible without a new definite set of ideal entities forming, and this only occurs during actualization. When one says, “I could move my cup two inches to the right,” one is giving a limited segment – a subset – of graded ideal entities. This subset is incomplete on its own, but may be in any number of definite sets. That is to say, one not giving a definite possibility, but rather giving a potential component of a possibility – a non-impossibility.
‘IT’S YOUR STORY, DON’T LOSE IT’ – USING SOUND AND IMAGE HERITAGE TO BRIDGE CULTURES Conversation with J. H. Kwabena Nkетia on the occasion of World Day for Audiovisual Heritage 2016 Judith Opoku-Boateng, J. H. Kwabena Nketia Archives, Institute of African Studies, University of Ghana Figure 1. Judith Opoku-Boateng with J. H. Kwabena Nketia. 1. Introduction On 27th October, 2016, the J. H. Kwabena Archives of the Institute of African Studies at the University of Ghana joined forces with UNESCO and other audiovisual archive institutions globally to celebrate “The World Day for Audiovisual Heritage” (WDAVH), a day set aside by UNESCO to raise general awareness of the need for urgent measures to be taken and to acknowledge the importance of audiovisual documents as an integral part of national identity. The theme for that year’s celebration was “It’s your story, don’t lose it.” My outfit organized a roundtable discussion on the theme and invited three renowned professors from the University of Ghana, who have had tremendous experience in fieldwork documentation, archiving, and dissemination. The three discussants were; Professor Daniel Avorgbedor¹, Professor John Collins², and J. H. Kwabena Nkетia, founder of what is now known as the J. H. Kwabena Nkетia Archives. After the roundtable discussions, I did a solo interview with him. ¹ Read more about Prof. Daniel Avorgbedor here: http://www.ug.edu.gh/music/staff/prof-daniel-avorgbedor ² Read more about Prof. John Collins here: http://www.ug.edu.gh/music/staff/prof-edmund-john-collins on UNESCO’s theme for the day. This interview collates the views I gathered from Nketia from the roundtable discussion and the subsequent solo interview in the comfort of his home in Madina, a suburb of Accra. 2. Brief on J. H. Kwabena Nketia J. H. Kwabena Nketia is a living legend. Born on June 22, 1921 at Asante Mampong in the Ashanti Region of Ghana, he is widely known and celebrated as a brilliant and versatile composer, an authority on African music and aesthetics, and a distinguished writer. He has over 200 publications not only in English, but also in his own mother tongue—Twi, in which he has written more than 20 books. He also has more than 80 musical compositions to his credit, including solo songs, and choral pieces. Nketia’s publications provide important and insightful material for the study of African history, mythology, literature, poetry, dance, drama, music, aesthetics, cultural anthropology, religion, and philosophy, creating a wealth of knowledge on African societies and cultures (Hagan, 2015). Nketia’s understanding of the African worldview is exceptional, and this partly comes from having been exposed to deep Akan culture from very early in his life (Euba, 2014). Nketia was the first African Director of the Institute of African Studies, University of Ghana. Nketia has lectured in leading universities around the world, including the University of California, Los Angeles (UCLA); Harvard University; the University of Pittsburg; and China Conservatory of Music. His Africanity was never blown away despite his international exposure. He is the recipient of numerous local and international awards Currently, he is the Chancellor of the Akrofi-Christaller Institute of Theology, Mission, and Culture at Akropong in Ghana; a Foundation Fellow of the Ghana Academy of Arts and Sciences; and an Honorary Fellow of the Royal Anthropological Society of Great Britain and Ireland; among other honors (Foundation, 2013). 3. The Conversation Judith Opoku-Boateng (JOB), Interviewer – Today is “World Day for Audiovisual Heritage,” a day that has been set aside by UNESCO to acknowledge and create awareness about audiovisual heritage. The theme for this year’s celebration is “It’s your story, don’t lose it.” You are a living legend in this country, and looking at your profile, it is evident that you have a special passion for audiovisual heritage preservation. You have donated your entire collection of field recordings to the archive at the Institute of African Studies at the University of Ghana, and the Archive has been named after you. What was your motivation when you started collecting music from indigenous communities in Ghana? J. H. Kwabena Nketia (JHKN), Interviewee – Thank you very much for this splendid opportunity to talk about heritage. UNESCO needs to be applauded for this initiative. I have always been interested in music and the traditional arts, and the stories behind them, and at a certain point in my life I had the opportunity of studying those kinds of materials, not only at home, but abroad. It seemed to me that my job was really to go into the business of collecting and systematizing what we have in Ghana, and later on also what we have in adjoining countries. And perhaps as a final objective, I would write the monograph, The Music of Africa (1974), because those collections give us some idea of the principles by which our traditional people have created their music. To move forward, we need to know our foundation and where we want to go in terms of our experience. So this is roughly what has guided me. I come from a traditional background where tradition was important. I was a child of non-literate and non-Christian parents, but I had the opportunity of going to school. So it seemed to me that I should supplement what the school offered with what I found in my own traditional society. In other words I kept up my traditional upbringing, and tried to learn about it and to share it, so that all of us who are in modern Ghana can appreciate our own traditions and how they can be developed and matched with the new traditions that are coming to us from various countries, so we can move forward as an independent country with our own and enlarged tradition in contemporary times. I wasn’t really among the class of people who have some western upbringing before they find their own culture, and so that enabled me to take up my traditional things seriously, but at the same time look at the new things that had come to us from the West because there is a way of enriching your experience when you borrow relevant things from other cultures and enhance and improve your own. **JOB:** Let’s go back to history. How were you able to capture all these traditions, especially looking at the kind of traditional background you are talking about? **JHKN:** Well, in the early days there was no recording equipment, nothing of the sort we have now, so you had to go to your teachers, parents, grandparents, and others in the tradition to learn from them; and so I did. My first attempt was provoked by a statement that the late Ephraim Amu³ made about going to the traditional people to learn from them. When I was in the teachers’ training college at Akropong,⁴ he saw me performing on the harmonium, imitating his compositional style. At the end of it he came to me and said, “Young man, I gather you’re interested in music,” and I beamed with a smile and said, “Yes.” And then he said, “Don’t copy my music! Go to the traditional people and learn our traditional music from them, because that is how I started.” So that was the best intellectual advice for a young person, but it was stimulating. So I went back to my hometown, but it was now the opportunity to look at that traditional background from another angle, from the angle of a boy who was going to school, learning about cultures and so forth, and who must be interested in his own culture. So that was the stimulus, and I started learning Adowa⁵ songs and so forth from my traditional people in Mampong Ashanti. What impressed me most were my teachers in the traditional setup, especially the Adowa queen mother, Dede Ama Tanowaa, who taught me about the Adowa repertoire and the tricks about Adowa. She was in charge of the Adowa group, and I must say that although she was non-literate, she was very intelligent and she would tell me about the structure of the song. She sings and tells me, “You know, this is the ‘call’ (‘ɔfre’) and this is the ‘response’ (‘nyesoɔ’); when the soloist interrupts, it is called (‘ntumu’), and when she sings a part on top of the chorus, it is (‘ntosoɔ’).” So it meant that this old lady who was non-literate was an intellectual because she was aware of the formal structure of the music. In other words, she had a certain sensitivity about the form and the theoretical structure, what we call the theoretical knowledge that we apply today. We all think that our non-literates probably do not dabble in intellectual things, but she was very systematic. It was all unwritten in her head, and I felt that my job now was to codify this, to bring this to our attention so we know exactly what our traditional people do. It is therefore our job to learn to sing the songs, and if possible to go beyond that and learn how to create new songs. Now in songs you are --- ³ Ephraim Amu, born on 13th September, 1899 and died on 2nd January, 1995, was a renowned Ghanaian composer, musicologist and teacher. ⁴ Akropong is the capital city of the Akwapim Traditional Area. It is located in the Eastern Region of Ghana, and in the Akwapim mountainous terrain, about 30 miles from Accra, the capital city of Ghana (Kwakwadum Association Inc., 2013). It has a 2013 settlement population of 13,785 people. ⁵ Adowa is a social dance performed at funerals and also during joyful occasions. It has grace of movements of the diminutive antelope after which it is named (Opoku & Bell, 1965). Judith Opoku-Boateng dealing with not only the music but also the language, the text, so you have a double task of knowing the language, how it works, and then the music, how you convert this into song. I was keen on seeking more knowledge on this “story” and not “losing it”, as UNESCO has it on today’s theme. There is a lot to learn from traditional people in terms of the structure of our traditional music, the words and all the other fine aspects of how you perform as a group, with a leader and the chorus and so forth. It was the intellectual knowledge behind this traditional thing that I had to discover in order to share this with my colleagues or with other people, and so this is the essence of what we describe now as musicology, knowing how the music is organized, its history, and so forth. We do all these things in our traditions but we don’t talk about our music, we don’t write; instead, we memorize the music and we perform and enjoy. What was missing was the literacy aspect, so my job then was to bring some literacy so that the songs are available in written form, and then we learn how to sing them. Even just getting the text without the music was very important, because you can enjoy what the text says in terms of what we now describe as literature. In other words, oral literature was treated as something that you think about and say in song, and not in writing because we hadn’t developed writing for it. JOB: Thank you Professor. How much is lost in the process of recording this information like you did, given that we did not have the recording devices? JHKN: Well this is when the invention of recording machines becomes important for us. Because, if I go there and learn to sing it, I can only share it when I sing it, but if I record it I can also play it for others to listen to and enjoy. So the recording thing came as an aide memoire, something that was enabling us to record our traditions or stories so we can listen back and enjoy them, so we can listen and discover how they were structured, so we can listen to them and see the topics that we dealt with, so we can listen and see how interpersonal relationships were ordered in traditional society and so forth. So, this becomes your oral literature of the people which they developed, which they don’t write down, but convey orally in songs and speeches. JOB: Professor Nketia, you have extensively documented Ghanaian musical traditions from the ten regions of Ghana as well as music from some African countries. When and how did you start this fieldwork documentation? JHKN: Well, it all started in 1952, when Professor Kofi Abrefa Busia, the head of the department of Sociology at the University of Ghana, decided to give me a research fellowship in sociology to study music. That was an exciting kind of departure, and from then I had my team. He made sure we had a car, a driver, a technician from the Ghana Broadcasting Corporation (the only broadcasting institution at the time) who handled the tape recorder, and an assistant in the field to help with interpretation and so forth. So the idea of being here at the University of Ghana and then traveling to various places in the country, to enjoy the music, but also record and bring it back with my team, started during Professor Busia’s tenure. Thus we had a model kind of archival collection. This collection covered all ten regions of Ghana. Now a collection is just a collection, but it becomes a proper archival thing when it is properly organized and made available for research and entertainment. 6 Kofi Abrefa Busia (1913–1978) was the first lecturer in African Studies and the first African to occupy a Chair at the University of Gold Coast, now University of Ghana. He later became the Prime Minister of Ghana, from 1969 to 1972 (Modern Ghana, 2006). JOB: So when you had the support from Professor Busia to carry out this documentation project, did you initially plan to cover all Ghanaian regional traditions? JHKN: The initial idea was to cover some traditions, but then the interest grew, so the bigger idea was to cover as many traditions as possible from all the regions of Ghana so that we have the whole of Ghana’s traditions in one place. In other words, the idea was to cover the entire country so that we use the archive to bridge ethnicities or cultures in Ghana—in a more appropriate sense, to unify the nation, so that someone from the Dagomba7 tribe, for example, can come to the archive and learn about ‘Agbadza’, an Ewe8 dance from the Volta region and vice-versa. The issue is, how can you develop a school system that is always singing God Save the Queen or Baa Baa Black Sheep, and not singing African songs, if you don’t provide them with the materials that our forefathers were using? How can you improve on that? And that is the challenge. And so the archive now becomes a very important, strategic thing for us in terms of music and its development in Ghana, because when you know the various traditions and you are a composer, you don’t compose only in your own traditions; you can compose in other traditions. That is what has been developed since Busia paved the way. Kwame Nkrumah supported this initiative in his time, it became fashionable for all of us to learn the music of other tribes. I refer to this as “bridging cultures and unifying the nation.” JOB: How do you feel, knowing that the materials you collected in the early 1950s and donated to the Institute of African Studies archives are being useful? JHKN: I am pleased that the University of Ghana has named this important facility after me. The point I want to make is that the archive is a very important source for development. The materials are there, but unless we have creative minds looking at how the materials may be used, they may lie there forever, and not be useful. So the stimulus to find out how our people were doing this in the past and how we could do it in the present defined the idea of making sure that even though we have several tribes, so to speak, we have different musical idioms, and that as a nation we can be familiar with the music of all our societies and that we can even perform their music. That becomes a challenge. But, we can’t do it without the archive, without the materials, and we can’t do it without the people in the archive systemizing what is there. And, we can’t do it without scholars being interested in systemizing the knowledge and creating new works embodying the tradition. So that makes the archive a very important thing in the evolution of tradition and style, and in terms of nation building. Fortunately, my research did not cover only Ghana, but other parts of Africa. JOB: Generally, would you highlight the role archives should play in preserving “our stories” so that we don’t “lose them”? 7 Dagombas are the second largest of the 54 ethnic groups in Ghana. 8 The Ewe occupy southeastern Ghana and the Southern Parts of neighboring Togo and Benin. **JHKN:** An archive is a backbone to culture and development, a backbone to education, a backbone even for philosophers, because you can learn about how your ancestors and other people were living and thinking. So the archive has become very important; preserving this for the country and for people who are curious to know their past, and to make good use of their past in the present is highly essential. For example, if you are a popular musician, we want the little thing that will make people dance; if you're another type of musician, maybe a church musician, we will want something that will make people contemplate. But with the archive, whatever your intentions are, you will find something that relates to what culture does and provides in the country. Our heritage is our story. Audiovisual heritage materials are our stories. Besides the written records, the films, musical recordings, and oral histories that have been captured in the 1930s, 1940s, 1950s, 1960s, and so on, on magnetic or digital formats as we have today, tell our story—the story about who we are and how we have developed or progressed as a nation or, generally put, as a global village. **JOB:** What is the way forward? **JHKN:** Well, the way forward is just what has begun here and in other countries. Setting up a proper archive and knowing that it is storing our field recordings and other commercial materials, but not only just storing, but making it possible for people from far and near to access them for application is what I am talking about. And I always insist on responsible access; by this, I mean creative and responsible use of the materials that have been collected by responsible and considerate people. Another point I want to make is that the archive curators or archivists have a huge responsibility of making the archive known to the public. They must devise creative ways to advertise the “super stories” they are preserving. The archivists must try to educate people about their collection and convince people that they will find something good there. For example, those in the music field who are trying to create new music must be able to access the old music from the archives to enhance their new creation. Even politicians need to consult the archive to learn from the old order and improve on it. Lastly, I would say that we should appreciate archives and make good use of them, no matter our backgrounds, because we would get to understand ourselves better. **JOB:** Thank you very much Professor Nketia for your time and the insights you have given us. **JHKN:** The pleasure is mine. 4. Acknowledgements The 96 year old interviewee is highly commended for making time to come to the Institute of African Studies to join in the Celebration of the WDAVH for these views to be gathered from him, and also to open his doors for the interviewer to come to his house for additional discussion. Secondly, I say big thanks to Ms. Rebecca Asseh for partly helping with the transcription of the interview. My colleague, Dr. Edem Addotey, of the Institute of African Studies, University of Ghana, deserves special thanks; two of the questions I asked Nketia were created by him. Professor Kofi Agawu of Princeton University in the US helped greatly by looking through the paper to make sure everything was well in place. 5. References
Quarantine in Question: The 1913 Investigation at William Head, B.C. LINDA M. AMBROSE Abstract. The Canadian government operated a quarantine station at William Head B.C. from 1881 to 1958. In the spring of 1913, a ship arriving from the Orient was detained because of smallpox. Subsequently, the station’s medical inspector, Dr. A. T. Watt, became the subject of a Royal Commission of Inquiry established to investigate his medical and administrative practices. That summer Watt committed suicide, but was posthumously exonerated from all the charges. This paper explores the conflicting class and racial questions that arose from this incident and the political reactions of those involved including the detainees, the government, and the media. Measures developed since the summer of 2003 to screen travelers entering into Canada in an effort to cope with SARS are not unprecedented in Canadian history. From 1881 to 1958, the Canadian government operated a quarantine station at William Head, B.C. on Vancouver Island to inspect the passengers on ocean-going vessels arriving at the ports of Victoria and Vancouver. That station was one of more than a dozen such facilities operated by the federal government from the 19th century well Linda M. Ambrose, Chair, Department of History, Laurentian University, Sudbury. into the 20th. In the spring of 1913 the medical inspector, Dr. Alfred Tennyson Watt, detained for quarantine a ship called the Monteagle, arriving from the Orient; there were two cases of smallpox on board. During the 17-day quarantine period from March 30 to April 16, Dr. Watt’s medical and administrative practices were called into question and later that summer, a Royal Commission of Inquiry was established to investigate him. During the course of the hearings, Dr. Watt committed suicide. After that dramatic turn of events, the inquiry report was filed and in it, Watt was posthumously exonerated from all the charges. Exploring this one dramatic incident in an isolated part of B.C. provides an opportunity to explore the history of William Head Quarantine Station itself, the conflicting class and racial questions that were at the heart of the episode, and the political reactions of those involved including the detainees, the government, and the media. Indeed, the history of quarantine practices in general is closely tied to matters of immigration, epidemics, and public health and recent historiography provides helpful guidance in interpreting the William Head investigation of 1913. A review of some of that literature is a helpful place to begin. Two general observations about the existing literature must be made at the outset. First and not surprisingly, the literature concentrates mostly on the 19th century because of the epidemics that plagued Canada’s urban immigrant-receiving cities. My second observation grows out of the first and is a logical extension of the immigration patterns dominating North America in the 19th century: more attention is given in the literature to Atlantic ports and their responses to disease than to those on the Pacific. Therefore, my study of a 20th-century incident on the West Coast of Canada breaks new ground in both chronology and geography. When exploring the existing literature on quarantine practices, it is useful to consider three different types of works. First, there are local or site studies that focus on communities or locations that dealt with specific outbreaks of disease or sites that came to be associated with attempts to screen immigrants such as Grosse Ile or Ellis Island. A second approach to the history of quarantine concentrates on various ethnicities such as the Irish immigrants who poured into Upper Canada in the early 1830s or Jewish immigrants arriving at New York City in the 1890s. Very often these works also point out the class differences that persisted throughout the 19th century and the different treatment afforded to passengers travelling in steerage as compared to cabin passengers. A third trend in the literature on quarantine is found in studies that focus on the politics of government response to immigration and disease, that is the enduring question of who is responsible to deal with issues like quarantine. Studies that focus on the rise of specific public health infrastructures and bureaucracies and those that concentrate on state formation generally are both included in this category. To begin with studies that focus on a particular locale, one could include those publications that describe national historic sites and particular incidents of disease with research potential for genealogists. 2 Passenger lists from quarantined ships are of special interest to genealogists and local historians and in 1994, The Island Magazine from Prince Edward Island published an article with helpful materials for family researchers entitled “The Ill and the Dying: Family Records from the Lady Constable Affair.” In 1844, the Lady Constable departed from Liverpool with 444 destitute Irish emigrants on board. Twenty-five people died en route to Charlottetown and eight more before the ship was quarantined with dozens of cases of typhus. Passenger lists and patient names of those treated during the disaster are of particular interest and the article includes reprints of that material. American studies of local history and epidemics are not difficult to find, in particular narrative accounts of how particular communities coped with specific outbreaks of disease. 3 A second theme in the literature around immigration and disease control is the focus on particular ethnic identities and the class distinctions that were commonly made between passengers of different financial means. While the Irish are the focus of much of the Canadian literature because of their large numbers during the first half of the 19th century, they are certainly not the only group that figures large in the literature. The work of American historian Howard Markel on Jewish immigrants arriving at New York City in the 1890s is an important place to begin. 4 Markel points out that while Jewish immigrants were blamed for the 1892 outbreak of typhus in New York City’s Lower East Side, the punitive health care measures that were put in place served only to spread the disease because infected people, fearful of doctors, hid themselves and fled from the authorities. In another study, Markel highlighted how double standards were applied to arriving passengers, based more upon their socio-economic status than their actual condition of health. 5 The William Head Inquiry of 1913 involved first-class passengers who were unhappy about their accommodation while in quarantine, but they only represented approximately 15% of the passengers who were held in quarantine. The vast majority of travellers were Chinese and Japanese. Therefore, one suspects that the identities of the detainees, both their class and their ethnic identities, must have figured very large in the story of what happened during this quarantine incident in 1913. Thirdly, by introducing politics into the analysis of the events that unfolded at William Head, one has the opportunity to compare this incident with others that stress the ideas, personalities, and power struggles that were at work behind the scenes but not far below the surface. Bruce Curtis, in an article published in the Canadian Historical Review in 2000, made a strong analysis of the forces of state formation that were driving the public response to the threat of a cholera outbreak in 1866. He con- cluded that “the 1866 cholera scare not only encouraged the formation of local sanitary and public health movements, but also led to serious attempts to invest the emerging domain of public health in statistical forms.” American literature on the history and politics of quarantine and epidemics is dominated by constitutional studies about state authority versus federal involvement in affairs of public health. The William Head incident had outcomes that illustrate how responsibility for quarantine in Canada was very much a political question. In Canada in 1913, the questions focused on the federal Department of Agriculture, which held responsibility for immigration and quarantine. But one must understand the fact that only 15 months after the very contentious and divisive 1911 federal election, political tempers were still flaring. Furthermore, in the racist context of anti-Oriental attitudes in British Columbia, economic interests in transpacific transportation were heightened and various political players were poised to capture the attention of the new Conservative Government, competing for resources. While the need to exercise control in the interests of public health were recognized, the individuals whose liberties were curtailed certainly did not appreciate or welcome measures which curbed their personal freedom. What happened at William Head in the spring of 1913 with the quarantining of one ship brings all the complexities of the themes of class, race, and politics into focus. This one incident can best be understood by using all three approaches, that is, by studying William Head as a place, by considering the race and class identities that were at stake, and by realizing that the power politics of public health versus personal liberties was very much at play. Studying William Head, B.C. as a place is fascinating. When the author made a site visit to the former quarantine station, to explore the scene of Dr. Watt’s work and the controversial 1913 incident, she had the rare privilege of being granted admission. It was a rare privilege because William Head is not a historic site. The former quarantine station is still a federal property, but it is now the site of the William Head Institution, a medium security prison. Permission was granted to enter the facility where the author spent the day working in the on-site archives. On that occasion, she was also permitted to tour the grounds, to view the remains of the wharf where Dr. Watt greeted the arrival of ships destined for Victoria and Vancouver between 1897 and July 1913, to walk through the graveyard where he and his staff buried the victims who succumbed to their diseases, and to see many of the original quarantine buildings where Watt developed then state-of-the-art technologies for the disinfection of passengers and their baggage. Local historians around William Head are well aware of the history of the site. Although the property’s current use does not permit on-site restoration or commemoration, the local museum, housed in the Metchosin Schoolhouse (just outside of Victoria) has artefacts and photographs from the quarantine station. Dr. Watt’s wife, Margaret Robertson Watt, was very active in the Women’s Institutes locally and at the provincial level, and it was through my biographical work on her that I first became interested in Dr. Watt himself, his work at William Head, and his untimely death during the 1913 inquiry into operations of the quarantine station. A publication of the Metchosin School Museum Society entitled *Footprints: Pioneer Families of the Metchosin District Southern Vancouver Island 1851-1900* has a two-page entry about the Watts, which concentrates more on the activities of Mrs. Watt than those of her husband. One suspects that his suicide and the controversy surrounding it led to a silencing of his story in the local community. William Head Quarantine Station was established in 1893, after the site at Albert Head was deemed unsuitable because it was not isolated enough from Victoria. In 1897, Dr. Alfred Tennyson Watt was appointed supervisor of B.C. Quarantines, to be stationed at William Head. He was well-qualified for this position. After graduating from the University of Toronto in 1890, he practised medicine in Victoria and became secretary to the Provincial Board of Health. By the time he accepted the appointment to become superintendent of Quarantine for British Columbia, his accomplishments included “inaugurating [sic] the first real public health work in this province [B.C.]. The Health Act was largely his work. Previously during the smallpox epidemic he had rendered good service.” As Table 1 illustrates, although William Head was a strategic location for transpacific travellers entering Canada, the number of ships quarantined in any given year was not large. Annual reports on the station, available from 1902 to 1914, show that during that 12-year period, Watt was responsible for the inspection of over 2700 ships. However, on average, only two ships per year were detained for quarantine. In the period from April 1, 1913 to March 31, 1914, the *Monteagle* was the only one. The declining number of ships inspected and quarantined is a reflection of the fact that new measures were in place in ports around the world for vaccination of passengers. Although smallpox continued to be the most common reason why Watt placed ships in quarantine, there was no major incident of smallpox outbreak or epidemic in Canada during the time that he served as the Chief Medical Officer at William Head. He was identifying individual cases, administering vaccinations, and imposing quarantine as a preventative measure so that he could verify that no additional cases were likely to occur. Watt performed these duties according to the regulations that were in effect from Ottawa and he did so with the help of a staff including a medical assistant. From December 1911 to April 1913, that assistant was Dr. J. R. Hunter. The main priority of Watt and his staff was to be in a constant state of readiness, so that as ships arrived, they could be inspected and either cleared to proceed to their port of entry or in the case of infectious diseases detected, and detained until the ship’s contents could be disinfected and its passengers and crew quarantined until all danger of new cases developing had passed. Table 1: Ships Inspected and Quarantined at William Head 1902-1914 <table> <thead> <tr> <th>Year Ending</th> <th>Vessels inspected</th> <th>People inspected*</th> <th>Ships quarantined</th> </tr> </thead> <tbody> <tr> <td>Oct 31, 1902</td> <td>442</td> <td>Not available</td> <td>3</td> </tr> <tr> <td>Oct 31, 1903</td> <td>393</td> <td>C 10098</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>S 20953</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 25148</td> <td></td> </tr> <tr> <td>Oct 31, 1904</td> <td>308</td> <td>C 10439</td> <td></td> </tr> <tr> <td></td> <td></td> <td>S 1570</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 20150</td> <td></td> </tr> <tr> <td>Oct 31, 1905</td> <td>176</td> <td>Not available</td> <td>0</td> </tr> <tr> <td>Apr 1, 1907</td> <td>254</td> <td>C 5358</td> <td>3?</td> </tr> <tr> <td></td> <td></td> <td>S 16671</td> <td></td> </tr> <tr> <td>Apr 1, 1908</td> <td>275</td> <td>48044</td> <td>6</td> </tr> <tr> <td>Mar 31, 1909</td> <td>261</td> <td>C 1218</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>S 13434</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 8428</td> <td></td> </tr> <tr> <td>Mar 31, 1910</td> <td>150</td> <td>C 5700</td> <td>1?? or 3??</td> </tr> <tr> <td></td> <td></td> <td>S 10846</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 12911</td> <td></td> </tr> <tr> <td>Mar 31, 1911</td> <td>164</td> <td>C 4734</td> <td>0</td> </tr> <tr> <td></td> <td></td> <td>S 14392</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 14073</td> <td></td> </tr> <tr> <td>Mar 31, 1912</td> <td>161</td> <td>C 4637</td> <td>2</td> </tr> <tr> <td></td> <td></td> <td>S 15752</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 15507</td> <td></td> </tr> <tr> <td>Mar 31, 1913</td> <td>162</td> <td>C 4940</td> <td>3</td> </tr> <tr> <td></td> <td></td> <td>S 17653</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 13725</td> <td></td> </tr> <tr> <td>Mar 31, 1914</td> <td>169</td> <td>C 5974</td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>S 16432</td> <td></td> </tr> <tr> <td></td> <td></td> <td>Cr 19611</td> <td></td> </tr> </tbody> </table> *C = Cabin passengers; S = Steerage; Cr = Crew members Dr. Watt’s annual reports about the quarantine station’s activities reveal that there were several explanations about the number of ships being quarantined in any given year. Worldwide acceptance of the importance of vaccination meant that mandatory precautions were being taken at most major ports throughout the Orient and as a result, fewer cases of contagious diseases were being detected among passengers. At the same time, Watt observed in 1907 that world events like the end to war between Japan and Russia had a direct impact on the number of ships arriving at B.C. ports. In 1905 he concluded that the $500 head tax imposed on Chinese immigrants to Canada “has prevented new arrivals entirely.” As well, effective January 1, 1905, ships arriving from San Francisco and ports north of there were exempt from inspection. Watt anticipated in 1907 that “work on the Panama Canal and the construction of a railway across Mexico from the Gulf to the Pacific…[means] there will be a new point on the coast from which steamers will come to B.C. ports.” Given the ethnic composition of the passengers and crew members who typically arrived at William Head on transpacific voyages, Markel’s work on the racism that greeted Jewish immigrants arriving at New York City in 1892 provides a very useful model for this current study. While the B.C. incident took place more than 20 years after the New York City outbreaks that Markel studied, the variables of race and class were still very much at play and those identities are central to this story. The ship that Dr. Watt placed under quarantine in the spring of 1913 had 379 passengers on board; 290 of them were Chinese travelling in steerage. There were 46 first-class passengers: 22 men and 24 women and children. Watt’s own account of why he detained the ship, which he wrote on March 31, 1913 was that “the report was given that one of [the] saloon passengers had developed varioloid on the night of the 28th. On examination of steerage passengers one of [the] Chinese was found also to have varioloid and to be showing much the same development. Both passengers had come on board at Hong Kong on 8th March so that the infection presumably was from an exposure in one of the ports of Japan, possibly from an ambulant case among the stevedores. All passengers have been landed also a number of the crew and the vessel which is undergoing disinfection is upon completion to be released.” The fact that two cases of smallpox were found, one in a white passenger, and the other in a Chinese passenger, immediately points up the class and racial identities that were at the centre of this incident. Anti-Oriental attitudes were so widely accepted in British Columbia in 1913 that they were openly discussed in the press, and indeed, in the assumptions about the type of quarantine facilities that were required for the different races. The buildings on the grounds of the William Head quarantine station reflect those assumptions. One building was designated the Chinese quarters, another, the Japanese. One might predict then, that race played a large part in the 1913 incident. But those ethnic divisions were so widely accepted that they hardly received comment in the inquiry. Instead, it was the inadequacy of the facilities and the service provided to the white first-class passengers that proved to be the central concern. This is still a racially defined crisis, but rather than one based on fear of Oriental immigrants, it was about the uncontested assumptions that white travellers were entitled to superior treatment because of their race and class. It was definitely a call for a two-tiered health care system determined by economic class and also by race. In the case of the Monteagle, the ship itself was only held for a few days before it was released, manned by a small crew who were deemed to be immune to smallpox either because of their vaccinations or previous exposures. The ship arrived in Vancouver on April 3, whither it was originally destined with its cargo of silk from the Orient. The remaining passengers however, were in for a much longer stay. The Vancouver Sun predicted on April 2, 1913 that “it is probable that the passengers will be kept at William Head until at least the end of the week, and probably a couple of days longer. Dr. Watt, the quarantine officer, is said to be a good entertainer and will provide every amusement possible for the enforced white guests, who will have the run of the station golf links and other forms of outdoor amusement provided.” But when that short stay dragged on for 17 long days, discontent arose among several of the cabin passengers. Indeed, before the end of the first week of their stay, several of those passengers were so distraught that they formed a committee that met “to protest against the unsatisfactory conditions prevailing at the William Head Quarantine Station.” At their second meeting, the committee members wrote a letter of complaint which they intended to submit to the Victoria newspaper, The Daily Colonist and also “to Government.” Because the Daily Colonist, like the Vancouver Sun, had predicted in its April 1st issue that the passengers would enjoy a “pleasurable time,” the committee members felt compelled to set the record straight. They wrote, We have read with considerable interest and astonishment the notice in your issue of April 1st, of the quarantining of the CPR mail boat “Monteagle” and your remarks on the pleasurable time in store for the sixty odd saloon passengers and CPR officials who have been detained for observation. The following facts regarding the disgraceful condition of the William Head Quarantine Station will show you our lot is far from Enviable. The unsuitability of the accommodation granted by the Government, its unsanitary condition, and the tardy assistance rendered passengers and CPR officials by the Agricultural [sic] Dept. called for protests from the “Monteagle” passengers. An indignation meeting was therefore convened and a committee appointed thereat to formulate specific charges which we regrettably find necessary to bring against Quarantine administration. The charges might be grouped under three heads; viz. (a) Housing; (b) Sanitation; (c) Administration. We shall deal with each in sequence.18 The protest committee comprised five individuals: Mr. R. W. Heberden, Chairman; Mr. D. L. Carrison, Secretary; and Mr. J. D. Grahame, Mr. A. G. Cohn, and Mr. A. C. Bromhead. In their letter to the editor, the committee members elaborated on each of these headings, and sent it off to the Victoria Daily Colonist and to Martin Burrell, the Conservative Minister of Agriculture. At one level, the protests that were being raised seem to be the self-centred complaints of a few disgruntled first-class passengers who resented that their civil liberties were being curbed because of one case of smallpox identified in a saloon passenger, and another case found to be a Chinese steerage passenger. At first glance it seems that this was a story about racial identities and class differences, but the events that unfolded clearly show that these concerns of race and class were commingled with a complex set of interpersonal conflicts and power struggles. Therefore, it is important to consider the politics behind the protest and the inquiry that followed it. Dr. Watt was no stranger to emergency public health measures. Over the past 20 years he had gained that experience as a public servant and guardian of public health. He responded to the accusations of the committee in a letter dated April 12, 1913 in which he expressed his frustration that the situation was escalating. “As the statement enclosed has been sent to the Minister of Agriculture anything I have to say in comment will be made in a communication to him.” In other words, Watt decided to defend himself directly to his political superior. But he did not let the letter to the press go without comment. I wish to repeat to you with regard to sending the letter to public press, that to send such a letter without the rider which you verbally agreed should be added, namely that buildings now being erected would in great part do away with any complaints, such as you have made,…and without correction of dates and figures and correction of statements re other matters which I showed you were inaccurate; and without statement going in that the temporary derangements on the first day were due to reconstruction; seems both unfair to the Department and misleading to the public. The detainees claimed that more than 600 persons were in quarantine when the actual number was less than 400. Moreover, Watt reminded the five detainees that when he was first told about the preparation of the letter, he was led to believe that it would be signed by all the passengers and that its purpose was to impress upon the Department of Agriculture that better accommodations were required at William Head, something that he would have welcomed if it meant that more resources would be put toward the improvements that were underway. With dismay, Watt wrote that “The letter has gone far afield from such original intentions and now is far from being a unanimous expression from the saloon passengers. All idea had to be dropped of getting even a majority to sign, so the letter must be looked upon as the expression of the individual views of those who signed.” While the Victoria newspaper refused to publish the protest letter, the Vancouver Sun took a very different stance. On April 17, the day after the quarantined passengers were finally released and had arrived in Vancouver, the Sun did not hesitate to “tell all,” based on statements made to them by disgruntled passengers. The headline at the top of page one, declared “Quarantine Station Conditions Cause of Serious Indictments by Passengers of Monteagle.” The most vocal was not among the five committee members, but he was a very public individual. Dr. Judson Burpee Black, of Windsor, Nova Scotia, was a past president of the Canadian Medical Association and a former member of parliament, a Liberal who had been defeated in the 1911 election. Dr. Black and his wife found their stay at William Head particularly uncomfortable, understandable perhaps given that they were the oldest passengers aboard the Monteagle, (Black was 71 years old and his wife was 68) and that they were on the final leg of their journey, a trip that had taken them around the world. Wearied by the whole experience, Black did not hesitate to assert that when he reached Ottawa, he would bring up the matter with the Honourable Martin Burrell, Minister of Agriculture, who was responsible for overseeing all of the Dominion quarantine stations. Meanwhile, Dr. Black made it clear when he spoke to the newspaper that “My indictment is against Dr. A. T. Watt, superintendent of the quarantine station, and I accept responsibility for that indictment.” Other evidence suggests that indeed Dr. Black’s protest against Dr. Watt was of a very personal nature. While the members of the ad hoc committee claimed to represent all of the saloon passengers aboard the Monteagle, there is strong evidence to suggest otherwise. Indeed, it seems that Dr. Black and the members of the committee, together with their wives, took the complaints much further and made them far more personal against Watt than other passengers were willing to do. Correspondence from other passengers to Minister Burrell suggests that Black’s protest and complaints in the Vancouver press were exaggerated. While most passengers agreed that the sleeping quarters allotted to first-class passengers were uncomfortably small, they also acknowledged that the station was under construction at the time of their quarantine, and they were quick to exonerate Dr. Watt from any undue blame for their inconvenience or discomfort in the episode. One letter that is particularly clear on this point and merits quotation at length was written on April 19 by R. S. Kinney, a teacher who was originally from Nova Scotia. Kinney wrote to Burrell stating that “From a conversation I had with Dr. Black before leaving the station, I should say that the grounds of his complaint against Dr. Watt [are] more personal than anything else.... Further I think that the so-called protest is more political than anything else, and it has been altogether too highly colored. I have the honor to be Sir your obedient servant, R. S. Kinney.” Despite the goodwill of Kinney and several other passengers who wrote similar letters, the call for a formal inquiry had already gone out and it was answered with the establishment of a Royal Commission of Inquiry. Commissioner H. W. R. Moore, Esq., a Victoria lawyer, was appointed to head the investigation and report back to the Minister of Agriculture. He visited William Head Quarantine Station on May 20, 1913 to view the facilities and then he presided at sessions of the Commission held in Victoria and at William Head on subsequent dates. During those sessions, Watt was called to testify and to defend his management record in the three areas of complaint lodged by the disgruntled passengers: specifically, housing, sanitation, and his own administration. Here one might predict that the white passengers were complaining of having to mingle with steerage passengers of Oriental origin. But that was not the case. The passengers were carefully separated according to their class: first-class passengers were kept well away from those in steerage and vice versa. But the conditions of the first-class accommodations formed the basis of the passengers’ complaints. The quarters were said to be unbearably small and inhospitable to families, the bathing facilities were said to be dirty, and the men’s toilet facilities were under construction during the first part of the quarantine period. Dr. Watt was questioned on all of these complaints and in his answers he explained that only the situation with the men’s toilets was really substantiated. That problem was resolved within a day of the ship’s arrival with the completion of the new septic system. There was virtually nothing in the investigation that overtly centred on themes of ethnicity although the entire episode was rife with racist, specifically anti-Oriental, assumptions. During the course of the inquiry however, the accusations became more personal and more sweeping and some dramatic events took place as the inquiry dragged on into the summer. Dr. Watt’s assistant, Dr. Hunter had tendered his resignation during the quarantine of the Monteagle, and after testifying before the Commission in May and again in June, he left for Europe. During the year and a half when Hunter was employed to assist Watt, their relationship was constantly strained. As the inquiry proceeded, it came to light that Hunter had previously complained to Ottawa about Watt and that he had been hoping to see an inquiry established to investigate his boss. The events in the spring of 1913 seemed to provide Hunter with the perfect opportunity to follow through on his complaints. Encouraged by the situation that was developing among some of the disgruntled Monteagle passengers, he tendered his resignation and waited for the Commission to be formed to investigate. Hunter’s accusations against Watt included failure to train and inform his assistant, misuse of government property (specifically a government boat), and lack of careful record keeping in financial accounts. These accusations were such that they cast aspersions on Watt’s integrity. In the final report of the inquiry, Commissioner Moore concluded that “in my opinion Dr. Hunter adopted a hot headed and unreasonable attitude. So far as he was concerned he seems to have done his best to make proper co-operation between himself and his superior officer difficult to the point of impossibility.” That difficult working relationship between Watt and Hunter was only one factor in a long list of things causing stress for Alfred Watt in the spring of 1913. Just a few months earlier Dr. Watt made an emergency trip to Ontario because his son was suffering from a serious case of pneumonia. He had joined his wife and family who had travelled to Guelph, Ontario seeking treatment for their son when he left William Head in December 1912 and returned in early February. Other health problems were plaguing the extended family as Watt’s brother Lorne was seriously ill during that same period. Indeed, Dr. Watt’s brother finally succumbed to his illness and died in mid-May of 1913. In fact Watt could not attend his brother’s funeral because it was held in Toronto on May 20th, the very same day that Commissioner Moore arrived at William Head to do his first site visit of the facilities and to officially launch the Royal Commission of Inquiry. The Watt brothers had been very close and the emotional strain of his brother’s death should not be underestimated. These personal troubles were the backdrop to Watt’s professional woes. The commission met for the last time on June 13, 1913 at the quarantine station, and then Moore was left with the task of writing his final report. In the course of doing so, the Commissioner learned on July 10th that when the Monteagle left Vancouver, outbound for a return trip to the Orient, two crew members took ill with smallpox the first day out after leaving William Head. He wrote to Watt’s lawyer, saying that while he did “not propose to hold another sitting of the commission on this point…I would be glad to have the benefit of any observations that your client, Dr. Watt may care to make in this matter, when this letter and the reply will be attached to the record of the Commission.” Watt’s lawyer replied a few days later to say that Dr. Watt was not well, but he hoped to be able to see him later that week with reference to this matter. A week later, on July 23rd, the lawyer replied to Moore that “Dr. Watt is not at all well and has been ordered by his medical advisors to have a complete rest.” The lawyer had spoken with Watt’s wife and received an explanation through her about the two crew members and their medical histories; one had been repeatedly vaccinated without a successful “take,” and the other had been vaccinated during the quarantine at William Head, but without success. Watt had been informed of these two cases, and on June 21, he had written a letter explaining the measures he had taken with the two men. All of this was communicated to Watt’s lawyer through Mrs. Watt. Then events took a very unexpected turn. One week after this exchange of correspondence between the Commissioner and the lawyer, Dr. Watt was dead. On July 27th Alfred Watt committed suicide by walking out of an upper-storey window in the Vancouver hospital where he was being treated for neurasthenia. After that tragic turn of events, the Victoria *Daily Colonist* was quick to point fingers at those who had driven Alfred Watt to his early grave. On July 29th, 1913 the newspaper’s editorialist wrote a glowing eulogy of Watt as a “public servant and guardian of public health” saying that transportation company officials and their passengers all agreed that Watt’s work was worthy of “sincere and hearty appreciation.” Then the accusations flew with this assertion: There is no room at all for doubt that Dr. Watt died a victim of political persecution. That is a hard thing to say, but that the shattered condition of his nerves which was the direct cause of his death was due to the persecution to which he has of late been subjected is beyond question. Far be it from us to suggest that those responsible for the recent investigation anticipated any such tragic consequences; but the fact remains that a valuable officer has been lost to the public service, a valuable life has been lost to the community as a result of an investigation into baseless charges involving the integrity of one in whom a high sense of honour was combined with an unusual degree of sensitiveness. The editorialist went on to declare that the grief caused to Watt by the insubordination, criticism, and accusations of members of his staff was a clear outcome of the worst aspects of political patronage at play due to “the change of administration in Ottawa.” That was a direct reference to the fact that Watt’s assistant, Dr. Hunter, was appointed by the new Conservative government, and that Watt had no power to fire him even though he was ill-suited to the quarantine station post, lacking both experience and a willingness to learn from and submit to Watt as his superior. An analysis of the documents created by the quarantining of the *Mon-teagle* and the subsequent inquiry into operations at William Head confirms that this episode in the history of early twentieth-century Canadian quarantine precautions was indeed a complex story of confluence. It is the story of place as a West Coast port adjusted to the changing context of transpacific travel trends. It is the story of identities as a small group of white, first-class passengers pressed for special treatment based on considerations of class and race. It is also the story of ideas; ideas about politics and power pitting public health control measures against personal liberties. These variables, at the centre of the 1913 incident at William Head, are still important considerations as Canada faces the 21st-century challenges of protecting public health and taking the necessary precau- tions to put preventative health care measures in place during emergency situations. ACKNOWLEDGMENTS The author gratefully acknowledges the Social Sciences and Humanities Council of Canada and the Laurentian University Research Fund. Thanks are due to Kristin Ireland and Lee Ann Spooner Fielding for their excellent work as research assistants. NOTES 2 For example, Grosse Ile became a National Historic site in March 1996, and it is a place of particular importance to the Irish. In 1997 Michael Quigley published an article “Grosse Ile: Canada’s Famine Memorial,” in which he explained the history of this site from 1832 to 1937, with particular attention to the Irish tragedy at the station in 1847 where thousands of Irish emigrants died. A similar publication from the Historic Sites and Monuments Board of Canada is Norman Anick’s 1984 “Gross Ile and Partridge Island Quarantine Stations.” 6 Bruce Curtis, “Social Investment in Medical Forms: The 1866 Cholera Scare and Beyond” *Canadian Historical Review* 81, 3 (September 2000): 379. 8 When the author visited William Head in the fall of 2000, the place was embroiled in yet another scandal, a very contemporary one. It was election year and the Reform Party of Canada was determined to gain political mileage from stories about how this prison might be more aptly called “Club Fed,” a place where prisoners mingle freely, live co-operatively, and even enjoy a private golf course. A. T Watt, Superintendent of BC Quarantines to the Minister of Agriculture, October 31, 1905 and April 1, 1907. 13 Markel, “Knocking Out the Cholera” p. 430. 16 “Liner Arrives Here with Half her Crew,” Vancouver Sun, April 3, 1913 p. 5; and “William Head Depot Grows Like Mushroom: Six Hundred and Fifty Passengers on Monteagle Form Quite a Townful,” Vancouver Sun, April 2, 1913 p. 7. 17 National Archives of Canada (NAC), RG 17, Volume 1190, Correspondence 232194, File 228852 “Minutes of a general meeting of the saloon passengers of the RMS “Monteagle.” 18 NAC, RG 17, Vol 1190, Correspondence 228392, 9 April 1913 to the Editor, The Daily Colonist, Victoria, B.C. 19 NAC, RG 17, Vol 1190 Correspondence 232194, File 228852, A. T. Watt to Messrs. Heberdeen, McCarrison, Grahame, Bromhead and Cohn, April 12, 1913. 21 “Quarantine Station Conditions Cause of Serious Indictments by Passengers of Monteagle,” Vancouver Sun, Thursday, April 17, 1913 p 1. 23 NAC, RG 17, Volume 1190, Correspondence 232194, File 228852, R. S. Kinney to Hon. Martin Burrell, Minister of Agriculture, Ottawa, April 19, 1913. 25 “His Death is Keenly Regretted: Mr. H. L. Watt is Called by Death, Well-Known Treasurer of Canada Life Assurance Company—Brother of Dr. A.T. Watt, of William Head,” The Daily Colonist, May 23, 1913, p. 10. 26 Among the items collected during the Inquiry, one personal item is preserved: a bookmark with an excerpt from Tennyson’s poem, In Memoriam that seems to have captured Alfred Watt’s feelings for his brother very effectively. The quotation reads: “To my dear Brother, ’But thou and I are one in kind/ As moulded like in nature’s mint/ And hill and wood and field did print./ The same sweet forms in either mind/ At one dear knee we proffer’d vows/ One lesson from one book we learn’d/ Ere childhood’s flaxen ringlet turn’d/d/ To black and brown on kindred brows.” NAC, RG 17, Vol 1190, File 228852. 27 NAC, RG 17, Vol 1190, Correspondence 232194, File 228852, Moore to Robertson, July 10, 1913. 28 NAC, RG 17, Vol 1190, Correspondence 232194, File 228852, Robertson to Moore, July 23, 1913.
Made in the skull's likeness: of transi tombs, identity and memento mori Jakov Đorđević Introduction Once there was an image of a king in the now lost Danse macabre mural at the cemetery of the Holy Innocents in Paris, and it was modelled after the tomb effigy of Charles VI. Thus, this cryptoportrait referred to the identity of a particular king, not only by the costume and regalia of French rulers, but also by similarity in appearance to the late monarch’s gisant. This example illuminates more than just the visual importance of tomb sculpture. It emphasizes the bond between sepulchral art of the later Middle Ages and the personal identities of those for whom it was commissioned. Sculpted effigies were truly markers of remembrance. By the thirteenth century it became customary for those of high rank to commission life-size figures for their tombs, and during the fourteenth century individualized features were slowly being introduced to the images of the represented. But to remember a deceased in this period virtually meant to remember praying for his soul so that he could be saved from purgatorial pains much earlier than he would actually have been without the aid of the living. There were many means of ensuring salvation in late medieval Europe. While some were more I would like to thank Professor Marek Walczak and Mateusz Grzęda for their efforts in bringing together the conference, and to the other participants for the stimulating discussions. Also, I am immensely grateful to Professor Jelena Erdeljan for the incisive comments and suggestions on a written version of my paper, as well as for her help with preparing the text in English translation. This paper contains some of the results achieved in the project no. 177036, supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia. Made in the skull’s likeness: of transi tombs, identity and memento mori orthodox than others, for those powerful and wealthy enough tomb sculpture was supposed to fulfil that goal. Cherishing the memory of the persons buried beneath, effigies were often designed to meet the task of redeeming the deceased they represented. Therefore, it was essential for the image above the entombed corpse to be able to herald the identity of the departed individual. The argument delivered in the following pages will, hopefully, bolstered this contention by showing how identity could be displayed in the late Middle Ages even through the means by which this was achieved paradoxically seem to dissolve the very idea of identity. Instead of a recumbent figure in a peaceful and deep sleep, or as a resurrected body looking toward the gates of Heaven, transi or cadaver tombs bore the representation of a deceased as an unsightly naked corpse, already affected by the grip of decay. Many variations of this type of funeral monument survive through Europe to this day, ranging from the so called ‘double-decker’ transi tombs to the verminous cadaver effigies. A number of them can be studied separately as the subjects in their own right, revealing particular design solutions that encouraged unique performative experiences in interaction with the beholders. However, this paper will concentrate on a trait common and essential to all transi tombs – their power to express identity of the dead buried beneath by turning the corpse into a ‘portrait’ of the deceased instead of an emblem of death. Purifying decay The meaning of an image does not depend only upon the intentions of its patron or creator, but also on the cultural background of its viewer. Gaze trained by all kinds 3 Indulgences might be the most famous example of the additional means in achieving salvation. Nevertheless, various amulets and magical objects and diverse ritual practices were also employed with the same goal, even though some of them were condemned by the official church teaching. See, for example, Roberta Gilchrist, ‘Magic for the Dead? The Archaeology of Magic in Later Medieval Burials’, Medieval Archaeology, 52, 2008, 119 –159. Particularly illuminating example of this way of thinking represent ‘sanctuaries of grace’, which were the places where stillborn babies were resurrected for just an instant in order to be baptized and, thus, not be damned to spend the whole eternity in the Limbo of small children. See Jean-Claude Schmitt, Ghosts in the Middle Ages: The Living and the Dead in Medieval Society, trans., Teresa Lavender Fagan, Chicago and London: University of Chicago Press, 1998, 145. 6 The good example represents the tomb of Alice de la Pole, duchess of Suffolk, with its almost totally hidden transi figure, which will be discussed in this paper, though briefly. of social experiences projects the acquired knowledge unto the ‘medium’ and out of that interaction a graspable image to the beholder is borne.\footnote{See Hans Belting, \textit{An Anthropology of Images: Picture, Medium, Body}, trans., Thomas Dunlap, Princeton and Oxford: Princeton University Press, 2011.} In other words, while extit{transi} tombs appear to be so explicit and clear in their unspoken message to the people of the twentieth or twenty-first centuries, that message was significantly different in the Middle Ages. Therefore, it is of utmost necessity to avoid reading today’s assumptions concerning death and dying back into these funeral monuments. Instead, one should try to observe them in the context of the desires that lead to their fashioning. The corpse on the tomb offered a statement about one’s fate in the afterlife. Bonds between body and soul became so intertwined in the later Middle Ages that the body could stand as a symbol for the soul.\footnote{R. C. Finucane, ‘Sacred Corpse, Profane Carrion: Social Ideals and Death Rituals in the later Middle Ages’, in \textit{Mirrors of Mortality: Studies in the Social History of Death}, ed., Joachim Whaley, London: Europa Publications Ltd, 1981, 60. On relations between body and soul in later Middle Ages, see also Caroline Walker Bynum, ‘The Female Body and Religious Practice in the Later Middle Ages’, in \textit{Fragmentation and Redemption: Essays on Gender and the Human Body in Medieval Religion}, New York: Zone Books, 1991, 181–238.} These bonds were present in both theological discussions and popular beliefs.\footnote{See Caroline Walker Bynum, \textit{Resurrection of the Body in Western Christianity, 200-1336}, New York: Columbia University Press, 1995, 279 –343.} The incorruptible bodies of saints are excellent indicators of this matter, as well as some funeral practices such as burying the dead with their shoes on and placing staffs beside them. These objects were supposed to aid the deceased along their journey to the other world, and their physicality was not perceived as contradictory to the spiritual form adopted by the deceased individual in the afterlife.\footnote{For these practices see Gilchrist, ‘Magic for the Dead’, 126 –128; and Peter Dinzelbacher, ‘The Way to the Other World in Medieval Literature and Art’, \textit{Folklore}, 97:1, 1986, 71.} Furthermore, the sufferings that the soul experienced in Purgatory were envisioned as somatic torments which could sometimes even be seen on the corpse of the dead, as attested in a number of stories.\footnote{See Bynum, \textit{Resurrection of the Body}, 295–296; Phillippe Ariès, \textit{L’homme devant la mort}, Paris: Editions du Seuil, 1977, 354. On Purgatory in general, see Jacques Le Goff, \textit{La naissance du Purgatoire}, Paris: Gallimard, 1981.} Therefore, it seems that the purifying of the soul was simultaneously followed by the cleansing of the body as well. And for a cadaver to be cleansed it had to be left without any trace of former flesh, in other words, it had to pass through the whole process of decay; to putrefy in order to be purified. Maybe this belief is most clearly grasped if one tries to understand the miracle of accelerated decomposition, which was believed to be the property of the soil brought from Jerusalem. Both Camposanto in Pisa and the cemetery of the Holy Innocents in Paris were said to possess earth for burial brought from the Holy Land that was able to decompose corpses in just a few days.\textsuperscript{12} Why would anyone desire such a miracle unless it promises salvific outcome? Therefore, miraculously accelerated dissolving of the flesh must have been perceived as affecting the time soul spent in Purgatory, shortening its stay.\textsuperscript{13} In context of bodily dissolution, Nancy Caciola’s study is of particular interest. By analysing medieval accounts and scattered folkloric beliefs, she has shown the presence of a notion in Northern Europe that a dead individual could not join the community of the ancestors before the process of bodily decomposition was fully completed.\textsuperscript{14} Moreover, during this period of transition the departed member of society was able to visit the living as an animated cadaver, a revenant, which means that his or her vitality was bound to the flesh, and with it the shadow or marks of the previous individual survived.\textsuperscript{15} Transi tombs brilliantly asserted this net of ideas and beliefs. The deceased was represented as passing through the liminal period of decay, which meant that his soul was undergoing purgatorial torments.\textsuperscript{16} The beholder was invited by the horrifying image to aid the dead individual because his prayer had the power to accelerate this process. Verminous effigies particularly carried the capturing strength to engage the viewer into the salvific performance of helping the dead.\textsuperscript{17} They showed cadavers filled with worms, snakes, frogs, even mice; all this in order to give the impression to the pious viewer that his prayer was truly effective and \textsuperscript{13} The miracle at Camposanto in Pisa is discussed in Jakov Đorđević, \textit{Makabrističke predstave u zapadnoevropskoj umetnosti od XIII do XV veka. Osobenosti ikonografije severno i južno od Alpa}, MA dissertation, University of Belgrade, 2013, 53–67. \textsuperscript{17} For a general overview on verminous effigies, see Sophie Oosterwijk, ‘Food for Worms - Food for Thought: The Appearance and Interpretation of the “Verminous” Cadaver in Britain and Europe’, \textit{Church Monuments}, 20, 2005, 40 –80. was banishing the loathsome vermin out from the corpse. Simultaneously, the soul in Purgatory was being freed from the corresponding sins.\textsuperscript{18} It is interesting to note that the \textit{transi} monument in Avignon of Cardinal Jean de la Grange was guarding only the corruptible – the perishable – parts of his body. He had demanded that after his death his corpse be boiled, and flesh and entrails separated from the bones. Thus, while the skeleton was buried in Amiens, under a different monument, the \textit{transi} tomb was supposed to provide prayers for the vanishing of the Cardinal’s sinful remains.\textsuperscript{19} \begin{figure}[h] \centering \includegraphics[width=0.5\textwidth]{tomb_chichele} \caption{Tomb of Archbishop Henry Chichele (d. 1443). Finished c. 1425, Canterbury Cathedral. Photo: Tony Jones.} \end{figure} On the other hand, it is notable that \textit{transi} tombs were often filled with heraldic tokens (figure 1). As on other contemporary funeral monuments, they were contributing to the construction of the deceased’s particular identity. However, they themselves were the image of the collective family body to which the departed strove to be incorporated. This urge was embedded in cadaver effigies quite naturally, for the deceased was represented as half-through in obtaining the ‘collective likeness’ of all members of the lineage. Only when nothing was left but the dry bare bones, the dead individual achieved the goal and became part of the community of ancestors. This belief was in perfect harmony with the doctrine of Purgatory, not interfering with its postulates. It should also be noticed that there was a striking difference in attitude of medieval people toward a decaying corpse as opposed to a dry bare skeleton. While the former was concealed far from the eyes of the living beneath the ground, the later was placed in the ossuary to be easily visible to all cemetery’s visitors. In medieval society the dead were an active part of the community, and the best evidence of this were the ossuaries placed within the church walls in such manner that skulls were directed toward the altar in order to be able to follow the celebration of the Mass together with the living. Being the bones of just the ordinary dead, without the remains of the condemned and excommunicated, they were truly the image of those who rest in peace and wait for the day of future resurrection of the flesh. Of flesh and clothes Powerful and wealthy people of the later Middle Ages strove to embody their personal desires, salvific hopes, and dynastic or communal aspirations through tomb sculpture. While the cost was an important factor in determining the appearance of a resting place, certain restrictions existed depending on the person’s position in society. Those of a lesser standing had to obey the stricter rules. Nevertheless, despite the many privileges, a king with his ‘body politic’ was common good to the realm and thus had to confine his personal desires. The 20 On the coat of arms as a ‘dynastic and genealogical face’, see Belting, An Anthropology of Images, 66 –67. 23 Bynum, Resurrection of the Body, 204. 25 In Florence, for example, the appearance of a tomb was strictly regulated by the state laws; see Andrew Butterfield, ‘Social Structure and the Typology of Funerary Monuments in Early Renaissance Florence’, RES: Anthropology and Aesthetics, 26, 1994, 47–67. 26 Queens, on the other hand, were not obliged to fulfill such royal expectations, and there ‘burial tradition’ is ‘more individualized’; see Pamela M. King, “‘My Image to be made all naked”: Cadaver Tombs and the Commemoration of Women in Fifteenth-Century England’, The Ricardian, 13, 2003, 312. On king’s body politic, see Ernst H. Kantorowicz, The King’s Two Bodies: A Study in Mediaeval Political Theology, Princeton and New Jersey: Princeton English monarch Edward IV expressed the desire in his will to be buried beneath a double *transi* monument; however, as in the case of Louis IX, his instructions were never carried out, apparently perceived as unfitting. Whereas Saint Louis wanted to be inhumed under an unmarked slab as a token of his Christian humility, the same need of presenting humbleness guided King Edward to make a demand as he did: ‘[W]e will oure body be buried lowe in the ground, and upon the same a stone to bee laide and wroght with the figure of Death […] and upon the same tumbe an Image of oure figure.’\(^{27}\) It is very suggestive that even though Edward IV clearly conceived the corpse as an emblem of death, the royal wish still seemed inappropriate. Obviously, his contemporaries could not see the figure of the decomposing cadaver as detached from the royal self, and, therefore, this image threatened the integrity of king’s body politic. This is not strange taking into account that all surviving double *transi* tombs indicate, way or another, that the decaying corpse is a representation of a distinguished dead individual. The memorial of Alice de la Pole, duchess of Suffolk, is particularly revealing. The unsightly figure of the noble lady is almost entirely hidden from the beholder’s gaze under a heavy structure while her resurrected body is placed on top of it (figure 2). However, albeit it cannot be seen from the outside, the sculpted cadaver is surrounded by devotional images of the Annunciation, Mary Magdalene, and John --- \(^{27}\) For the tomb of Edward IV, as well as for the excerpt from his will, see Kenneth Rooney, *Mortality and Imagination: The Life of the Dead in Medieval English Literature*, Turnhout: Brepols, 2011, 5; and for the tomb of St. Louis, see Parkinson, *The Likeness of the King*, 103. the Baptist.\textsuperscript{28} Set above the late duchess’ metamorphosed body, these paintings established perpetual visual prayer and spiritual protection for the deceased in the same manner as the word ‘Emmanuel’ inscribed twice next to the corpse of Henry Chichele did.\textsuperscript{29} These are testimonies which unequivocally imply that the waning figure on the transi tomb cannot be perceived as a mere personification of death, because none of the mentioned prophylactic elements would have had any meaning unless they were placed beside the image of remains of the deceased individual. But the question of how an identity was created through a cadaver monument is very thought-provoking. While measurements and weight were true marks of the self in the late medieval period, transi tombs utilized traditional representational means of portrayal like heraldic tokens and inscriptions.\textsuperscript{30} The double-deckers could even rely on the upper figure as well. However, clothing was never employed on any sculpted or carved cadaver, testifying that the idea of the corpse’s nudity was an integral part of transi tombs. Looking from a geographical point of view, this type of funeral monument is a phenomenon belonging to Europe north of the Alps. Yet, one can still find in Florence the sole existing example that contradicts the imaginary barrier which \textsuperscript{28} King, ‘My Image to be made all naked’, 307. \textsuperscript{29} Cohen, Metamorphosis, 46. For the image and text as a perpetual prayer on the wall, see Madeleine Gray, ‘Images of Words: Iconographies of Text and the Construction of Sacred Space in Medieval Church Wall Painting’, in Sacred Text — Sacred Space: Architectural, Spiritual and Literary Convergences in England and Wales, eds, Joseph Sterrett and Peter Thomas, Leiden and Boston: Brill, 2011, 15–34. divides Apennine Peninsula from the northern European regions. The remarkable and curious tomb slab of Antonio Amati, doctor of law, strongly stands out among contemporary Florentine sepulchral art, for it bears the only known representation of the dead with the cadaverous face in Italy (figure 3). However, Kathleen Cohen excluded it from her seminal study *Metamorphosis of a Death Symbol* because she determined a set of criteria that refused to take into account any figure of a corpse which was clad in the ceremonial garments of deceased’s former office. Drawing from her research based upon the northern cadaver monuments, she justifiably concluded that the true *transi* tomb always carried the image of a naked or shrouded body already affected by the grip of death. Thus, the tomb slab of Antonio Amati is even more surprising, not simply because of its geographical placement, but because the late doctor of law was represented as a fully clothed man with death’s-head instead of a face. The Florentines had strict regulations when it came to organizing funerals and erecting funeral monuments, therefore, it is not particularly challenging to determine the place of Amati’s tomb in the broader social context of this Renaissance city. Belonging to one of the four elite groups, the patron was entitled to arrange his burial space with a carved portrait of himself in the interior of the church of Santa Trinita. The slab with its effigy was designed in the third quarter of the fifteenth century and compared to the other contemporary sepulchral representations, it does not actually stand out as exceptional in anything but this *macabre* element. Truly, cadaver tombs were not part of the experience of *Trecento* and *Quattrocento*. However, the *macabre* notion was well known to Italy through numerous depictions of the tale of the Three Living and the Three Dead, the theme of Triumph of Death, and the images of Adam’s skull. The notebook of Jacopo Bellini attests that even more ideas of this sort travelled back and forth across the Alps – in one drawing the artist envisioned how a *transi* tomb of a professor should --- 32 ‘I consider the transi to be a representation of the deceased as a corpse, shown either nude or wrapped in a shroud.’ (Cohen, *Metamorphosis*, 9). 33 ‘None were located in Spain, nor any in Italy that met the specific criteria used for the transis.’ (Cohen, *Metamorphosis*, 189). 34 Those elite groups were: ‘knights and aristocrats; doctors of law and medicine; higher ecclesiastics and other important religious figures, such as distinguished abbots; and persons who were buried at public expense as a reward for their service to the city’ (Butterfield, ‘Funerary Monuments’, 55). have been designed.60 Yet, even there the corpse is represented naked, unlike the one on Antonio Amati’s slab. As opposed to vanitas portraits, where portrayed people proclaimed their virtuous nature almost as exemplary models,37 cadaver effigies stressed the humility of the dead, never striving to turn them into models for imitation. The cadaver’s nudity was always intended as an expression of humility and humbleness. It was an ‘exposure of the private to the public’.38 But, because the person was present in the body after death, the image of a corpse was also, as Katharine Park noticed, ‘an immediate image of the self’ and, thus, ‘still a portrait’. Therefore, the naked putrefied flesh of a transi effigy was an instrument of fashioning identity as well. The lack of physiognomic likeness was not of any big importance, for, even when it was used in sepulchral art, it represented only an additional, accompanying tool. Coats of arms, inscriptions, regalia, garments, gestures, and even material,39 were all much safer agents to be entrusted with the task of communicating an identity, because they were not counting on recognition based upon someone’s memory, but the established system of signs.40 However, in early Renaissance Italy it seems that physiognomic likeness held a stronger standing thanks to the tradition of employing death masks into the execution of funeral effigies. Dating back to the late thirteenth century, the time that set the urge among powerful members of learned circles to express their inner virtues through the images of their bodies,41 certain gisants on Italian soil were modelled after the casts taken from the faces of the --- 60 For the image, see Panofsky, Tomb Sculpture, 66, fig. 268. 37 Vanitas portraits emerged in the sixteenth century, and they were showing their sitters in special settings decorated with objects connected to the ideas of time and mortality. The person depicted was usually supposed to express his own awareness of transience by contemplating or pointing toward the skull, thus showing his inner virtue. Vanitas portraits are briefly discussed in Sophie Oosterwijk, ‘Dance, Dialogue and Duality: Fatal Encounters in the Medieval Danse Macabre’, in Mixed Metaphors: The Danse Macabre in Medieval and Early Modern Period, eds, Sophie Oosterwijk and Stefanie Knöll, Newcastle upon Tyne: Cambridge Scholars Publishing, 2011, 40, with additional bibliography. 38 Binski, Medieval Death, 150. 39 ‘Poetics of materials’ had a great role in fashioning many objects during medieval time. Reliquaries in particular expressed the nature of the treasured relics through gold and precious stones – the incorruptible substances similar to the bodies of saints. Similarly, material of a tomb effigy, with its own properties, was able to express inner nature of the royal deceased. See Binski, Medieval Death, 150. deceased. According to high scholastic teachings, especially those of Thomas Aquinas, the body became ‘the external manifestation of the spiritual fulfilment’, and, thus, the lifelike sepulchral images expressed inner spiritual achievements, i.e. holiness of the dead. It seems that during the next two centuries this practice of ‘recording likenesses’ became accessible to others than just ‘God-given dignitaries’. There are certain sources that might suggest the employment of death mask in Europe north of the Alps from the fourteenth century on as well, yet it seems that this practice was limited to the circles of royal members only. Furthermore, utilization of lifelike ex-voto busts in Italy is also important since votive offerings were always the bearers of the suppliant’s self. While people in the North usually submitted themselves to God by giving wax offerings equal to their weight and height, in Italy waxen votive images based on facial casts were also popular. It might be that this practice gave higher authority in the Apennine Peninsula to the likeness as an agent of defining identity than this concept enjoyed in the sepulchral art beyond the Alps. Anyway, the decision to omit the individual facial features on Antonio Amati’s slab, and utilize collective future likeness destined to all humankind in the city where ‘documenting’ facial features was very popular, was certainly an expression of humility and humbleness, even though the deceased was represented as dressed. Still, this does not explain why he had to be in his academic gown. Another important aspect of cadaver tombs was the corpse’s vitality, for the dead bodies were either shown as experiencing convulsion or represented as true revenants – the undead. Katharine Park has argued that this belief in corpse’s 43 Olariu, ‘Aquinas’ definition of the imago Dei’. 45 Olariu, ‘Körper’, 85–89. 46 See n. 31. 48 In Europe north of the Alps, even when votive offerings in wax were rendered as the figures of the suppliants who ordered them, they were idealized images with only possible ‘hints’ of physiognomic likeness. Cf. Sarah Blick, ‘Votives, Images, Interaction and Pilgrimage to the Tomb and Shrine of St. Thomas Becket, Canterbury Cathedral’, in Push Me, Pull You (vol. 2): Physical and Spatial Interaction in Late Medieval and Renaissance Art, eds, eadem and Laura D. Gelfand, Leiden and Boston: Brill, 2011, 41–44. vitality was unknown on the Apennine Peninsula as a result of a different attitude toward the process of dying. While in the North people believed that the moment of death marked the beginning of the liminal period during which a personhood slowly faded away, in Italy it was perceived as a radical separation of body and soul.\(^{49}\) Therefore, it is not strange that Antonio Amati is represented as completely immobile and lifeless – as a matter of fact, just like the other Florentine gisants. He is portrayed as lying on a pillow under a canopy, wearing his academic gown and hood – i.e. in the same manner as he must have looked like during his funeral (except for the death’s-head instead of his face).\(^{50}\) Katharine Park has also stated that Italians ‘at every level of society’ identified self with the soul, which made body become only an object of memory and commemoration in the hour of death.\(^{51}\) While the same idea is undeniably present in theology of Thomas Aquinas,\(^ {52}\) her argument can be challenged to some extent. This is because, beside the wonder-working incorruptible relics of saints, certain practices such as the already mentioned miracle of accelerate decomposition in Pisa, performative tomb effigies positioned near the altars, and will of Pietro de Vico testify to the contrary. They all imply that corpses were manipulated in order for the deceased to gain salvation, which consequently means that bonds between body and soul could have been re-established even in Italy, though through some necessary ritual practices. Testator Pietro de Vico ordered that his corpse be divided into seven parts as a penitent renouncement of seven deadly sins before his remains were buried.\(^{53}\) The Camposanto in Pisa was the celebrated cemetery-reliquary cherishing the earth brought from Jerusalem that was said to have the property of decomposing cadavers in just three days.\(^{54}\) This miracle was highly desirable, as attested by the sources,\(^ {55}\) and obviously had salvific potential of accelerating, not only bodily decomposition, but also the painful time the soul had to spend in Purgatory.\(^ {56}\) And finally, Geraldine Johnson has \(^{50}\) ‘Effigies on tombs, both in relief and in the round, refer specifically to the privilege of having one’s corpse exposed for view during the funeral, and served the same function of establishing the deceased’s membership in a prestigious elite. It is for this reason that these effigies record in exact detail the distinctive ceremonial clothing of the deceased.’ (Butterfield, ‘Funerary Monuments’, 60). \(^{52}\) See Bynum, Resurrection of the Body, 259. \(^{55}\) See n. 13. \(^{56}\) Dordević, Makabrističke predstave, 63–67. convincingly shown how certain Italian tomb effigies were used, not simply as the objects which celebrated cult of memory, but as the active participants of the Mass performed at the altar, thus re-enacting some of the absolution rites.\textsuperscript{57} Therefore, in order to become ‘an immediate image of the self’, representation on Antonio Amati’s slab had to replicate the supposed look of the deceased from the funeral, i.e. the moment when bonds between body and soul (self) were restored. If he had been represented as a naked corpse, he might not have been perceived as the image of an individual in need that was crying for help, which transi effigies successfully managed to do in the North. Even the upper part of Amati’s slab stressed the existence of a connection between body and soul further through the emblem made out of putto (soul) that is holding coat of arms (identity) and skull (dead body), keeping them all assembled as a true psychosomatic unity.\textsuperscript{58} In northern Europe the corpse on a cadaver monument was not supposed to bear any trace of clothing because it was associated with sin unlike to that that vermin represented; only certain insignias could pass as acceptable, and even they were employed very rarely. There are a few transi memorials, belonging to abbots and bishops, which bear the carved images of crosiers and mitres beside the representations of cadavers.\textsuperscript{59} They were not intended as instruments of defining individual identity so much as they were supposed to refer to the ultimate transience of earthly glory, thus inducing compassion in viewer’s gaze. They were heightening the humility of the deceased who, though once great, fell so low in their death. One Book of Hours, today in the British Library (Harley MS 2917), contains a miniature (fol. 119 r.) that illustrates this same idea by utilizing insignias, only, in this case, through the story of the Three Living and the Three Dead (figure 4). Another example of this concept can be traced back to the transi monument of Jean de la Grange where death’s-heads with royal and prelatic headgears, placed above the cadaver, were supposed to play an identical role, adding their inaudible voices to the lament of the dead cardinal.\textsuperscript{60} Only in the case of one exceptional slab of an unmarried girl named Ingeborch the story is somewhat different. The crown placed upon the female corpse’s head indicates the deceased’s maidenly status, an inner virtue, and thus figuring as not just the attribute of identity, but as a symbol that \textsuperscript{57} Johnson, ‘Activating the Effigy’. \textsuperscript{58} The Putto with a death’s-head is an old symbol, dating back to Antiquity. While it can stand for the carnal principles, in combination with the skull it is more probable that it was adapted to the Christian body-soul dualism. Very suggestive is the putto’s head which replicates the skull’s position, standing immediately next to it. On this ‘emblem’, see further Horst W. Janson, ‘The Putto with the Death’s Head’, \textit{The Art Bulletin}, 19:3, September 1937, 423–449. \textsuperscript{59} For the images see Sophie Oosterwijk, “‘For no man mai fro dethes stroke fle’": Death and danse macabre iconography in memorial art’, \textit{Church Monuments}, 23, 2008, fig. 2; and Oosterwijk, ‘Food for Worms’, fig. 5; Panofsky, \textit{Tomb Sculpture}, fig. 271. \textsuperscript{60} See Morganstern, ‘La Grange Tomb’, 61–62. promises future resurrection of the body.61 However, here the headgear cannot be perceived as belonging to regalia of any sort because it does not signify Ingeborch’s earthly station. Nevertheless, there is one other illuminating miniature that actually might explain the reasons behind the northern hostility toward representing the dead clad in other than the white shrouds. In the Flemish manuscript of the Golden Legend, which is preserved today in Mâcon library, in the chapter devoted to the Day of the Dead one illumination shows two scenes – the legend of the grateful dead and the story of a ghost who paid a visit to his friend (MS 3, fol. 25 v.).62 The later tale is represented as a conversation between the corpse dressed in lavish garment and the living man who is lying in bed with his wife. According to the --- 61 Symbols of resurrection were not unusual on transi tombs. The word ‘Emmanuel’ on tomb of Henry Chichele, which has been already mentioned, is a good example, just like the small scallop shells, traditional symbol of eternal life, on the tomb of François de la Sarra. See Cohen, *Metamorphosis*, 83. On Ingeborch’s tomb slab, see Oosterwijk, ‘Dance, Dialogue and Duality’, 14, 33, fig. 3. 62 For the image see Schmitt, *Ghosts*, fig. 29. story, the dead on that occasion informed his friend that he had to wear the mantle he had stolen while alive, and its weight in Purgatory is unbearable. This, I presume, is the kind of message that would have been grasped by a beholder from the North had he had the opportunity to see Antonio Amati’s tomb slab. To him the incorruptible clothing, untouched by decay, on a half-decayed corpse would have implied a sin that cannot be redeemed. Even snakes and toads would have seemed less evil, for they, just as the dissolution of the very skin, represented liberation of the soul from past transgressions; they were leaving the body unlike the untouched garment of Antonio Amati. On the other hand, a Florentine viewer was able to comprehend the same meaning that was offered to the Northerners by their own cadaver monuments thanks to the academic gown. It helped in creating the notion in the beholder’s mind that the body and soul were still connected, just as in funeral ritual, thus testifying that the humble state of the former in earth resembled the penitent state of the later in Purgatory. Therefore, this is the reason why Amati’s tomb should be considered to be a ‘true transi’, for those very differences from its northern counterparts made it become transi in Florentine context. **Sum quod eris vs. memento mori** The cadaverous gisants were meant to provoke live interaction, a discussion even, between the viewer and the image. This encounter is usually summarized by a famous Latin motto memento mori (remember that you must die). However, to do so is to reveal only a partial dialog of a much more complex story. Because the dead on a transi tomb was an individual speaking from beyond, I am going to argue that sum quod eris (I am what you will be), an excerpt from the tale of the Three Living and the Three Dead, would be more convenient reference in order to describe the experience surrounding cadaver monuments than the memento mori motto, since the later distracts attention from the fact that putrefied corpses represented on tombs should be perceived as truly defined portraits. Medieval society was made out of bonds between its members, and the dead were actively participating in it, demanding their share. From the early days these bonds were established as a form of gift exchange where every gift required a suitable counter-gift. Without the counter-gift the imbalance would become intolerable, threatening the receiver. This idea, though not that obviously exposed as in medieval popular stories, was enduring as a cornerstone of social relations through the whole Middle Ages. The living were obliged to take care of their dead, and the dead had to repay them. In rural communities caring for the deceased members secured fertility. In higher social classes the inheritor of a title had to rely --- 64 Geary, *Living with the Dead*, 36, 87. 65 Geary, *Living with the Dead*, 78. on the relations he had with the deceased nobleman in order to preserve the authority of his claim to the position he was holding. In return for the authority, which was bestowed upon him by the dead, he had to pray for that departed noble individual, alleviating the purgatorial pains. These ties did not need to be established only while both parties were among the living. A man already dead could make a new bond with the person still alive. Many stories about apparitions from Purgatory confirm that, and transi tombs should be seen as belonging to this peculiar context. The idea of gift-exchange embedded in sepulchral art is the most evident through the examples of tomb inscriptions which promised indulgencies to all those who prayed for the deceased. Nevertheless, ties could have been forged by much subtler ways. The living corpse on a cadaver monument was supposed to be perceived, through the performative interaction with the beholder, as a ghost from Purgatory or a good revenant who was passing through the purgatorial pains by bodily decomposition. The bond between them was established in the moment of the viewer’s identification with the deceased, when he learned about his own mortality and future fate. However, though he was seeing himself in the image of the cadaver, he was also aware that the representation before him belonged to the particular departed individual. The same was true for the tale of the Three Living and the Three Dead. While the three noblemen saw themselves in the corpses, the dead were apparitions from Purgatory, and they were explicitly asking of the living in some written versions of the tale to pray for them, after they had taught them the moral lesson. Their famous words were often embedded into the transi tombs Cf., for example, the story of a ghost who attacked a simple traveler in order to make the man help him: Andrew Joynes, ed., Medieval Ghost Stories: An Anthology of Miracles, Marvels and Prodigies, Woodbridge: Boydell Press, 2001, 168–170. Here the traveler had to supply the dead with the appropriate aid in exchange for his life. It is particularly interesting that it is explicitly mentioned in the story that the dead took shape of a cadaverous king similar to the contemporary depictions of the Three Living and the Three Dead; see Joynes, ed., Medieval Ghost Stories, 169. See, for example, Binski, Medieval Death, 113. There were also transi tombs which promised indulgences, see Cohen, Metamorphosis, 68. The corruption of the corpse in the Middle Ages was also perceived as the ‘seventh and final gift of the Holy Spirit’ – an image that should inspire knowledge of transience and mortality, and help people to stay on the road of righteousness that would lead them back to the Garden of Eden. It was said that Adam became aware of the gravity of his doing only after he had seen Abel’s decaying corpse. Therefore, it was necessary for someone else to die so that he could become aware of his own mortality. See Joseph Leo Koerner, ‘The Mortification of the Image: Death as a Hermeneutic in Hans Baldung Grien’, Representations, 10, 1985, 52–53. For a full transcription of one poem which explicitly mentions intercessory prayers, see Stefan Glixelli, Les Cinq Poemes des trois morts et des trois vifs, Paris: Champion, 1914, 53–63. Made in the skull’s likeness: of transi tombs, identity and memento mori giving voice to the cadaverous effigy who was, consequently, saying: sum quod eris. This lesson of mortality was the debt that had to be repaid, because, as Jean-Claude Schmitt stated, ‘in Christian society a dead person could provide no greater service than to invite a living person to prepare for death’. The tomb slab of Antonio Amati is not the only image in Florence that could be said to belong to the transi tradition. Though famous Masaccio’s skeleton in Santa Maria Novella defied all rules of portraying an individual, refusing to employ any of the instruments of defining identity, it would be very unusual not to consider it a depiction of a particular deceased, taking into account the inscription above the image: ‘I was once what you are and what I am you also shall be’. It seems that earlier scholarship concerning the Trinity fresco was right to propose that this work of the famous artist was just one part of a tripartite special composition, which also included a now-lost tomb slab and an altar. Representing the dead under the crucifix beside Adam’s skull was known in fifteenth-century Florence, as attested by the memorial panel of Jacopo del Sellaio. Here two plague victims lie beneath the cross with their faces uncovered, receiving the grace of redemption along with the forefather. More importantly, Christ’s sacrifice is not shown as a standard Crucifixion scene, but as an emblem of eternity, especially popular in miniatures representing the final of six triumphs of Petrarch’s Trionfi – the Triumphus Aeternitatis. God the Father, supporting the cross, and the dove of the Holy Spirit, flying above Christ’s head, brought into the depiction not only the assurance in deliverance from original sin, destined to all humanity, but also the promise of resurrection of the body, triumphing over Time. This was true for the Masaccio’s fresco as well. However, here the skull and the dead body were blended into one. The connection between the lifeless bones and the soul (self) must have been understood as ‘activated’ due to the salvific drops fallen from Christ’s wounds. The skeleton was undressed because it had to be identified as truly being Adam, but, at the same time, through the viewer’s involvement in the special arrangement of this funeral setting (consisting of Masaccio’s fresco, alter and the now lost funeral slab) it was supposed to be simultaneously perceived as the image of the deceased patron 72 There are many examples of transi tombs which bear the characteristic verse of the Legend, see Cohen, Metamorphosis, 16, 31, 33–38, 69, 71–77. 73 Schmitt, Ghosts, 75. 75 On the panel, see Cohen, Metamorphosis, 108. buried there as well. While the inscription of a name on the tomb slab and the performance of commemorative masses were powerful instruments of engaging the beholder, guiding him toward the dead, this fresco’s share in that process was the inscription ‘I was once what you are…’ – the warning discussed in the paragraph above. During the late decades of the fifteenth century true memento mori objects started to develop, anticipating notions and attitudes toward death characteristic for theologians of the Reformation. They were often designed in such manner that their massage would not be apparent at the first glance. Through the game of revealing concealed layers, as in the case of interactive engravings, or discovering hidden images seen only from particular angles, as was usual with jewellery decorations, a person was introduced to the hard truth of earthly transience, but in an amusing way. These objects distracted attention from the dead in need and concentrated only upon the fate of the beholder. Motto memento mori broke the bonds between the living and the dead, subtly implying that every person was responsible for his or her own death. There were no ‘you’ and ‘I’ and the salvific help between the worlds – a notion distant and strange to the medieval transi tombs. Cadaver effigies were meant to make the living become aware of their own mortality, but at the same time they were emphasizing that the represented deceased were the particular departed individuals in need of help. Therefore, remembering one’s death was always followed by remembering the dead. Epilogue Rules set in the later Middle Ages concerning execution of transi tombs endured in some parts of Europe well into the early modern period. Usually, this was the case with places that dealt with currents of Reformation and Counter-Reformation in their own manner, negotiating new tendencies with old ways. Thus, one can find in Ireland a true ‘medieval’ cadaver slab made in 1627, which was even accompanied with the characteristic inscription: ‘I was as thou art and thou yet shall be’. However, important changes emerged during the sixteenth century in big centres where new intellectual, theological, and artistic ideas proliferated and flourished, and the new demand were set before the image of the corpse. A dead body, even though affected by death, had to resemble the individual physical appearance of the --- 77 Cohen, Metamorphosis, 44. Jakov Đorđević Made in the skull’s likeness: of transi tombs, identity and memento mori deceased.\textsuperscript{80} Because the physiognomic likeness was becoming more and more accepted to a wider audience as necessary means by which portraits signified their subjects,\textsuperscript{81} representations of particular dead people had to possess facial features corresponding to their likeness while they were still alive. The faceless putrefied corpses, on the other hand, lived on as the images reserved for the personification of death alone. \textbf{Jakov Đorđević} is a PhD candidate in Art History at Belgrade University. In 2014 his MA paper on late medieval macabre art was awarded The National Museum in Belgrade Prize. He is a member of research project “Serbian Medieval Art and Its European Context”, sponsored by the Ministry of the Republic of Serbia. He is currently researching iconography of body and death in Byzantium and Mediterranean world in the late Middle Ages. jakovdj@gmail.com \textsuperscript{80} For the images see in Cohen, \textit{Metamorphosis}, figs. 66, 67, 77, 81, 82, 90, 91, 111.
Earlier hatching and slower growth, a key to survival in the early life history of Norwegian spring spawning herring Slotte, A.; Husebø, Å.; Berg, Florian; Stenevik, E. K.; Folkvord, A.; Fossum, P.; Mosegaard, Henrik; Viikebø, F.; Nash, Richard. D. M. Published in: Marine Ecology - Progress Series Link to article, DOI: 10.3354/meps12682 Publication date: 2018 Document Version Publisher's PDF, also known as Version of record Citation (APA): Earlier hatching and slower growth: a key to survival in the early life history of Norwegian spring spawning herring Aril Slotte1,*, Åse Husebø1, Florian Berg1,2, Erling Kåre Stenevik1, Arild Folkvord1,2, Petter Fossum1, Henrik Mosegaard3, Frode Vikebo1, Richard D. M. Nash1 1Institute of Marine Research (IMR), PO Box 1870 Nordnes, 5817 Bergen, Norway 2Department of Biology, University of Bergen, PO Box 7800, 5020 Bergen, Norway 3Technical University of Denmark, Kemitorvet, Bygning 202, 2800 Kgs. Lyngby, Denmark ABSTRACT: Faster growth in fish larvae is often associated with enhanced survival, and here we investigated whether surviving juvenile Norwegian spring spawning herring Clupea harengus L. generally come from a pool of fast-growing larvae. Growth after hatching was determined using daily otolith increment widths at distances of 37.5 to 137.5 µm from the core in fish from 3 selected year classes (1991, 1992 and 1996) and compared among post-larvae (body lengths 20 to 30 mm) sampled on the shelf in May–June and 0-group juveniles sampled during the autumn in fjords and Barents Sea nurseries. In general, daily otolith growth after hatching was significantly higher in the larvae rather than in the surviving population of 0-group herring at comparable sizes. Larvae with a more similar growth rate to that of 0-group were those that hatched early in the year, were the slowest growers and were located close to the coast and far to the north in mid-May. We therefore propose that survival until 0-group may increase by hatching earlier in the year. This may result in a faster northward larval drift in colder ambient temperature. Although this will induce slower growth, the mechanism behind increased survival is larval drift trajectories and early arrival in nursery areas prior to the increasing predation risk developing northwards during spring warming. However, size (not growth rate) may still be important, as early hatching also may result in earlier metamorphosis, despite the slower growth. KEY WORDS: Herring · Larvae · Otolith · Growth · Drift · Survival Payne et al. (2013) demonstrated that the observed decrease in recruitment was accompanied by reduced larval growth rates, supporting the growth-rate hypothesis. Mortality at the juvenile stage has been found to be strongly size-dependent (Caddy 1991), including in NSS herring (Barros & Toresen 1994). Some results, however, show that certain predators in fact may choose the largest individuals (Litvak & Leggett 1992, Pepin et al. 1992). In addition, it has been demonstrated that early-hatched larvae may experience lower predation pressure and have higher survival than those hatching later in the season, even if the early larvae experience lower temperatures and growth rates (Fortier & Quinonez-Velazquez 1998, Lapolla & Buckley 2005, Nishimura et al. 2007). Husebø et al. (2009) supported this hypothesis using historic NSS herring data, demonstrating a negative correlation with hatching time estimated from larval surveys and recruitment. The basis for the hypothesis of higher survival in early-hatched NSS herring is linked to the early life history of the stock, with a very wide spawning area and long distances between hatching locations and nursery areas. NSS herring are substrate spawners, utilising hard bottoms (shell sand, gravel, stones), which occur over a wide area along the Norwegian continental shelf (down to 250 m depth) from 58 to 70° N (Slotte 1999, Sætre et al. 2002b). The majority of the larvae drift northwards to the Barents Sea nursery area (Holst & Slotte 1998). However, retention over bank areas is common (Sætre et al. 2002a), and a minor portion of the larvae are entrained into coastal and fjordic nursery areas along the coast (Holst & Slotte 1998). Hence, NSS herring larvae generally drift over large distances between the hatching and nursery areas, experiencing a wide range of environmental conditions and variable predation pressure. Regarding the potential mechanism between early hatching and larval survival, Husebø et al. (2009) concluded that the range and abundance of important predators of herring larvae would generally tend to increase and become more active as spring warming progresses northwards along the coast, and that early hatching and rapid northward drift could therefore lead to reduced predator overlap in time and space. However, Husebø et al. (2009) could not exclude the possibility that early spawning may have advantages that are more related to ambient temperatures, feeding success and growth than to predation pressure. Following this, Vikebø et al. (2010) carried out model simulations of NSS herring to test the effects of early hatching at the main spawning grounds off Møre (62 to 64° N) on larval drift routes and ambient temperature. The study indicated that early spawning leads to faster northward displacement of larvae, with a drift route closer to the coast in lower ambient temperatures compared with larvae hatched later in spring. Hence, it was concluded that early hatching would not be favourable due to temperature-dependent growth, although the possibility of improved feeding conditions could not be excluded. Later, Vikebø et al. (2012) tested the potential overlap with prey by exploring the development of phytoplankton blooms along the coast. They found a delay in the bloom with increasing latitude of 37 d within the spawning habitat of NSS herring. Overlap between larval hatching and blooms was clearly highest at the main spawning grounds in the south (62 to 64° N), suggesting that match with prey availability may be an important factor in the selection of spawning grounds by NSS herring, and that early spawning only would be successful if the herring migrated southwards to spawn. Since the early 1990s, otolith microstructure analyses have been used in many studies to examine early life growth, condition and survival of NSS herring (Moksness & Fossum 1992, Fossum & Moksness 1995, Moksness et al. 1995, Folkvord et al. 2004). Based on these studies it has become clear that discernible increments observed in larval herring otoliths outside the core area typically are due to daily growth. Thus, increment size at some distance outside the core area will reflect the daily otolith growth at a given otolith size, and indirectly, larval size. However, due to the variable otolith growth immediately outside the core area, precise age and corresponding hatching day estimations are not possible without assumptions about the initial otolith growth in the first days after hatching (Fox et al. 2003). Moreover, the results clearly demonstrate that the daily growth of the larvae increases with temperature when food is available (e.g. Folkvord et al. 2004). The principal hypothesis tested in the present study was that fast growth rate is a determinant of survival through the larval drift phase between the spawning and nursery grounds. Growth rate comparisons were undertaken using daily otolith increment widths at selected distances from the core, corresponding to periods of larval drift, for larvae and the surviving 0-group stages. The 1991, 1992 and 1996 year classes were chosen for this study as they characterised the variability in the stock, with the 1991–1992 year classes representing years with early hatching and high recruitment in comparison to the late hatching and low recruitment in 1996 (Husebø et al. 2009). It is also important to note that the 1991–1992 year classes grew up in the Barents Sea, whereas the 1996 year class was relatively more abundant in the fjords (Husebø et al. 2007). 2. MATERIALS AND METHODS 2.1. Larval and environmental sampling Data used in the present study on larval distribution, density and their ambient temperatures at sampling, as well as individual larval data used for analyses of daily otolith growth, were collected during annual field studies off the Norwegian coast in May (Nedreaas 1995). The survey timing, coverage, stations and sampling in 1991, 1992 and 1996 are given in Table 1 and Figs. 1 & 2. After 1992, the larval survey design for the shelf area was changed to only include sampling along a single south–north transect (Figs. 1 & 2). Although this means that the larval sampling in 1996 was not consistent with 1991–1992 spatially and temporally, it was still chosen for interesting comparative reasons; 1991 and 1992 were years with early hatching and good recruitment, whereas 1996 was a year with a very late and broad hatching (see Fig. 4) and low recruitment (Husebø et al. 2009). In fact, 1996 was a year where the main part of the 1991–1992 year classes carried out their first spawning, and this happened in a second, later spawning wave (Slotte et al. 2000), thus the broad hatching curve. We found that the south−north sampling transect in 1996 overlapped with the 1991–1992 distributions and represented quite well the average larvae present at that time. We acknowledge that it is not directly comparable with the broader sampling of larvae in 1991–1992, but we have chosen to treat the 3 years equally in the analyses, as we do not consider that the spatial differences in sampling would significantly influence the main results and conclusions. Table 1. An overview of years, areas and periods of sampling of the different Norwegian spring spawning herring life stages, along with number of stations and individuals analysed for daily otolith growth. See Fig. 1 for detailed positions of samples <table> <thead> <tr> <th>Year</th> <th>Area</th> <th>Period</th> <th>Life stage</th> <th>No. of stations</th> <th>No. of individuals</th> </tr> </thead> <tbody> <tr> <td>1991</td> <td>Norwegian shelf</td> <td>7−24 May</td> <td>Larvae</td> <td>23</td> <td>212</td> </tr> <tr> <td>1991</td> <td>Fjords south of 68° N</td> <td>21−28 Nov</td> <td>0-group</td> <td>7</td> <td>59</td> </tr> <tr> <td>1991</td> <td>Fjords north of 68° N</td> <td>7−10 Nov</td> <td>0-group</td> <td>4</td> <td>58</td> </tr> <tr> <td>1991</td> <td>Barents Sea</td> <td>28 Aug, 13 Sep</td> <td>0-group</td> <td>4</td> <td>65</td> </tr> <tr> <td>1992</td> <td>Norwegian shelf</td> <td>08–13 May</td> <td>Larvae</td> <td>19</td> <td>272</td> </tr> <tr> <td>1992</td> <td>Fjords north of 68° N</td> <td>5−12 Nov</td> <td>0-group</td> <td>4</td> <td>62</td> </tr> <tr> <td>1996</td> <td>Norwegian shelf</td> <td>11–12 Jun</td> <td>Larvae</td> <td>7</td> <td>314</td> </tr> <tr> <td>1996</td> <td>Fjords north of 68° N</td> <td>29 Nov−10 Dec</td> <td>0-group</td> <td>9</td> <td>69</td> </tr> </tbody> </table> Fig. 1. Sampling sites of otoliths in larval (blue dots) and 0-group (red dots) Norwegian spring spawning herring in 1991, 1992 and 1996. Red lines: limits between areas used for spatial comparison of 0-group otolith growth (coast south, coast north and Barents Sea) Water column structure at each station was measured with a CTD (Seabird SBE911) with a rosette. Temperature and salinity at 20 m depth was taken as representative of the sampling station. Sampling of larvae was undertaken using a MIK (2 m Midwater Ring Trawl; ICES 2013), multiple opening/closing net and environmental sensing system (MOCNESS; Wiebe et al. 1985) and pelagic trawl. Nedreaas (1995) suggested that the capelin trawl (modified Harstad trawl) gave the most representative estimates of postlarval densities. Also, Fossum (1994) concluded that there was no significant difference in herring length distributions sampled with the MIK and the Harstad trawl, and therefore samples collected with the Harstad trawl gave reliable qualitative estimate of true herring larvae distribution and size structure present in the sampling area. The modified Harstad trawl (Godø et al. 1993) had an 8 mm mesh cod end liner. This trawl was towed at 3 nautical miles (nmi) h\(^{-1}\) for 0.5 nmi with the towline at the surface, then 0.5 nmi at 20 m, and 0.5 nmi at 40 m depth. The total towing distance was 1.5 to 1.8 nmi. Trawling was undertaken during both day and night. The entire catch was sorted and counted, and density in terms of numbers per trawl hour was estimated by fish species. In addition, a random sub-sample of each species was measured (fork length, nearest 1 mm), and representative samples retained for further analyses, e.g. otolith microstructure analyses. 2.2. 0-group sampling The 0-group NSS herring from fjord and Barents Sea nurseries and from the same cohorts as the larvae (1991, 1992 and 1996) were selected for otolith microstructure analyses (Table 1, Fig. 1). The material was selected from the large archive of NSS herring otoliths held by the Institute of Marine Research (IMR), and all 0-group samples were collected with R/V ‘Michael Sars’ using a standard Harstad trawl, towed at 3.5 nmi h\(^{-1}\). To ensure a wide latitudinal range of data, otoliths were selected along the coastline (classified as coast south and north of 68°N) as well as in the Barents Sea (only in 1991) (Fig. 1, Table 1). It would have been preferable to also have representative otolith data from the 0-group in the Barents Sea in 1992 and 1996, as the Barents Sea is the main nursery area and only a minor part of the stock grows up in the fjords (Holst & Slotte 1998). However, otoliths are not routinely sampled in the Barents Sea during the annual August–September 0-group trawl survey. The exception was from 4 trawl stations taken by the R/V ‘G.O. Sars’ in 1991. These were included in the analysis as representative of the main part of the year class growing up in the Barents Sea. 2.3. Otolith microstructure analyses The otolith microstructure data from larvae were a part of P. Fossum’s previously published and ongoing work, and he made these available at the start of the present study. The herring larvae he and his team analysed were preserved in 80% buffered ethanol immediately after capture. The methodology used for preparing and reading the otoliths is laid out in Moksness & Wespestad (1989). All increments, from the core to the edge of the otolith were measured. In the case of 0-group herring, both sagittal otoliths were removed immediately after sampling, placed in black trays and embedded in histokitt resin for regular age reading. For this study, the otoliths selected for microstructure analyses were removed from these black trays with a scalpel and mounted in thermoplastic cement on glass slides. During the mounting process, heating was used on the glass slides and minor histokitt remains mixed with the thermoplastic cement. In order to examine the microstructure of 0-group otoliths we used grinding and polishing methods described by Mosegaard & Madsen (1996) (Fig. 3). Polished otoliths were examined using a Leica DMLB light microscope (Leica Microsystems) at 400× and 800× magnification connected to a digital camera and a computer. Pictures (3840 × 3072 pixels) of the otoliths were taken with a digital camera (Nikon DXM 1200F) with use of Eclipse.net software (Laboratory Imaging). The width of each otolith increment was measured as the distance between 2 opaque zones using the image analysing software Image-Pro Plus v.4.0 (Media Cybernetics). Examination of the otoliths was carried out along the same transect from the core to the posterior margin along the longest readable axis, and increments were measured at distances from the core up to a maximum of 250 μm. 2.4. Data analyses Increments less than 37.5 μm from the otolith core were excluded from further analyses because of the uncertainty of increments and widths in the period immediately after hatching (Campana & Moksness 1991, Fox et al. 2003). An otolith size of 37.5 μm in Slotte et al.: Hatching time, growth and survival in herring Area analysed Hatch check 25/μm intervals used in analyses 37.5 62.5 87.5 2 11.5 137.5 Otolith size (μm) Larval body length (mm) Fig. 3. (a) Daily growth increments in a ground and polished otolith from 0-group Norwegian spring spawning herring. The hatch check (dotted circle) and distances from the core are shown, and the area and intervals used in the analyses of daily otolith growth in larvae and 0-group herring are marked. (b) Mean larval body length related to otolith size in the 1991–1992 material, where otolith sizes are grouped into the same intervals as used in the analyses for the present study. The interval 37.5–137.5 μm from the otolith core analysed for daily growth of 0-group corresponds to larval sizes of between 20 and 30 mm body length. Error bars are 95% confidence limits. herring corresponds in general to a larval length of approximately 20 mm (Folkvord et al. 2004, 2009), also fitting well with the data on larvae used in the present study (Fig. 3). Following this, any aging of the larvae would be considered uncertain, and for the 0-group the lack of precise measurements of increments all the way from the core to the edge of the ground and polished otolith would also prevent any aging in number of days. Still, a link between age and sampling time of larvae was necessary for analysing effects of hatching time on the daily otolith growth. To get a proxy for the age of larvae, we used the total number of increments ($N_{\text{increments}}$) beyond 37.5 µm from the core up to the edge of the otoliths. Due to the survey design, northern stations were sampled 7 to 17 d later than southern stations, resulting in different catching dates ($\text{Day}_{\text{Catch}}$). To account for this timing difference, we based our analyses on standardised time within a year. This was done by estimating the day of year when the larvae had attained an otolith size of 37.5 µm ($\text{Day}_{37.5}$) as: $$\text{Day}_{37.5} = \text{Day}_{\text{Catch}} - N_{\text{increments}}$$ \hspace{1cm} (1) Further, within each year class, the earliest day of year with sampled larvae attaining an otolith radius of 37.5 µm was defined as: $$\text{Minimum}(\text{Day}_{37.5}) = \text{Day}_{1}$$ \hspace{1cm} (2) with all other larval increment data being re-scaled to this day, hereafter termed relative hatching day. This allowed for a direct comparison of larval otolith growth between different relative hatching times within a year class independent of the varying sampling times. Increments greater than 137.5 µm from the otolith core were also excluded from further analyses, due to the lack of overlap between larvae and 0-group data at these distances. Frequency distributions of $\text{Day}_{37.5}$ suggested that the larval material came from a wide range of hatching days, and with a broader range in 1996 than in 1991–1992 (Fig. 4), also leading to variable otolith size distributions. The number of larval individuals available for analyses of daily increments was significantly reduced when growth at increasing distances from the otolith core was analysed (Table 2), where in the end only data from the earliest hatched larvae were available. At distances greater than 137.5 µm from the core, the number of available larvae with large enough otoliths was very small (1991 and 1996), or even lacking (1992). Within the chosen limitations of analyses of daily otolith increments from 37.5 to 137.5 µm from the core, the data were grouped into 25 µm intervals (i.e. ![Figure 4. Relative hatching day ($\text{Day}_{37.5}$) distribution of Norwegian spring spawning herring larvae from the 1991–1992 and 1996 year classes sampled in May and June](image) <table> <thead> <tr> <th>Year class</th> <th>Interval (µm)</th> <th>N</th> <th>$N_{\text{increment}}$</th> <th>$\text{Day}_{37.5}$</th> </tr> </thead> <tbody> <tr> <td>1991</td> <td>25</td> <td>212</td> <td>25.9</td> <td>17.7</td> </tr> <tr> <td>1991</td> <td>50</td> <td>212</td> <td>25.9</td> <td>17.7</td> </tr> <tr> <td>1991</td> <td>75</td> <td>197</td> <td>27.3</td> <td>16.7</td> </tr> <tr> <td>1991</td> <td>100</td> <td>131</td> <td>31.8</td> <td>13.9</td> </tr> <tr> <td>1991</td> <td>125</td> <td>45</td> <td>38.4</td> <td>10.0</td> </tr> <tr> <td>1991</td> <td>150</td> <td>16</td> <td>41.0</td> <td>7.0</td> </tr> <tr> <td>1992</td> <td>25</td> <td>272</td> <td>21.2</td> <td>15.2</td> </tr> <tr> <td>1992</td> <td>50</td> <td>272</td> <td>21.2</td> <td>15.2</td> </tr> <tr> <td>1992</td> <td>75</td> <td>249</td> <td>22.1</td> <td>14.4</td> </tr> <tr> <td>1992</td> <td>100</td> <td>86</td> <td>27.5</td> <td>10.1</td> </tr> <tr> <td>1992</td> <td>125</td> <td>1</td> <td>35.0</td> <td>4.0</td> </tr> <tr> <td>1992</td> <td>150</td> <td>0</td> <td></td> <td></td> </tr> <tr> <td>1996</td> <td>25</td> <td>314</td> <td>23.5</td> <td>26.8</td> </tr> <tr> <td>1996</td> <td>50</td> <td>313</td> <td>23.5</td> <td>26.8</td> </tr> <tr> <td>1996</td> <td>75</td> <td>262</td> <td>26.4</td> <td>23.9</td> </tr> <tr> <td>1996</td> <td>100</td> <td>148</td> <td>33.9</td> <td>16.5</td> </tr> <tr> <td>1996</td> <td>125</td> <td>67</td> <td>40.8</td> <td>9.8</td> </tr> <tr> <td>1996</td> <td>150</td> <td>11</td> <td>48.1</td> <td>3.4</td> </tr> </tbody> </table> distance 50 µm represents the interval 37.5<62.5 µm and 75 represents the interval 62.5<87.5 µm, etc.; Fig. 3, Table 2). Each individual larva and 0-group herring was assigned a mean increment width over the 25 µm intervals, and these mean values were used for graphic visualizations in the figures. However, for statistical analyses, all single measurements of increments at the individual larval level were included. Statistics and graphical output was undertaken in the R software (R Core Team 2017). Otoliths from 20 randomly selected 0-group individuals from several stations were analysed twice to determine the precision of measurements of daily otolith growth. Based on a linear effects model with individual otolith as a random factor, there was no statistical difference between the results of the 2 measurements (ANOVA: $F = 0.60, df = 1, p = 0.44$), suggesting that the measurements were reliable. To test for differences in daily otolith growth, linear mixed-effects models were run with increment width as the dependent variable. The optimal structure of the random effects (a) was tested using a likelihood ratio test based on the models fitted by restricted maximum likelihood estimations (REML) (Zuur et al. 2009). For all models, the structure of the random effect was station/individual otolith. Furthermore, based on REML fits, the fixed effects structure was optimized using marginal F-statistics (Pinheiro & Bates 2000). For all models, both the random effect a and the residual ε were assumed to be normally distributed with mean of zero and variance $\sigma^2$. All mixed-effects models were fitted using the ‘lme’ function within the R package ‘nlme’ (Pinheiro & Bates 2000). For all models, the structure of the random effect was station/individual otolith. Furthermore, based on REML fits, the fixed effects structure was optimized using marginal F-statistics (Pinheiro & Bates 2000). For all models, both the random effect a and the residual ε were assumed to be normally distributed with mean of zero and variance $\sigma^2$. All mixed-effects models were fitted using the ‘lme’ function within the R package ‘nlme’ (Pinheiro & Bates 2000). The first model had the form of: $$\text{Width} = \alpha + \beta_1 \times \text{dis} + \beta_2 \times \text{Group} + \beta_3 \times \text{Yclass} + \beta_4 \times \text{dis} \times \text{Group} + a + \epsilon \hspace{1cm} (3)$$ Increment distance from the core (dis), year class (Yclass) and life stage (Group; larval and three 0-groups) were included as categorical factors in the fixed effects structure. The next models were run for each year class individually and had the following form: $$\text{Width} = \alpha + \beta_1 \times \text{dis} + \beta_2 \times \text{Day}_{37.5} + \beta_3 \times \text{dis} \times \text{Day}_{37.5} + a + \epsilon \hspace{1cm} (4)$$ $$\text{Width} = \alpha + \beta_1 \times \text{dis} + \beta_2 \times \text{Area} + \beta_3 \times \text{dis} \times \text{Area} + a + \epsilon \hspace{1cm} (5)$$ Relative hatching day (Day$_{37.5}$) and sampling area (Area; see areas in Fig. 2) were included as categorical variables in the fixed effects structure. The hatching day was divided into the following intervals: <15, 15 <25, 25<35, ≥35 and the 0-group. Note that due to the use of area and hatching day as categorical variables it was not possible to run a model with both variables included. A model with hatching day and area included would allow for a direct comparison of the effect on otolith growth of each variable. p-values are given in the text in cases where the life stage, hatching day (Day$_{37.5}$) or area significantly influenced the otolith increment width. Significant differences among several variables were identified using Tukey’s HSD tests. ### 3. RESULTS Daily otolith growth over the analysed interval (37.5 to 137.5 µm from the core) was significantly higher in the larvae than in the surviving population of 0-group herring when tests were run for all 3 year classes (ANOVA: $F = 88.4, df = 3, p < 0.001$) (Fig. 5). When comparing raw data points of the measured increment widths (Fig. 5), there was a clear overlap between the larval and 0-group data, but at the same time a tendency of the 0-group to have some measurements of low daily growth outside of those observed in the larvae, especially at distances 62.5 to 112.5 µm from the core. No significant difference in daily otolith growth was found between 0-group herring of the 1991 year class collected in southern and northern fjords and in the Barents Sea (Tukey’s HSD tests: $p > 0.2$). Hence, for the rest of the statistical testing, 0-group data were merged regardless of area of collection. A closer examination of the daily otolith growth in larvae revealed that relative hatching day (Day$_{37.5}$) was a significant factor within each year class (ANOVA 1991: $F = 37.0, df = 4, p < 0.001$; 1992: $F = 26.5, df = 4, p < 0.001$; 1996: $F = 537.5, df = 5, p < 0.001$); growth tended to decrease with earlier hatching of the larvae (Fig. 6). When testing for differences between larvae and 0-group at different hatching day intervals, the daily otolith growth over the analysed interval (37.5 to 137.5 µm from the core) did not differ significantly between the earliest hatched larvae (hatching days ≤25) and the 0-group (Tukey’s HSD tests: $p > 0.05$) in all 3 year classes. The observed reduced growth in the earliest hatched larvae was further analysed by comparing the daily otolith growth between larvae from 4 different sampling areas (see areas in Fig. 2) (Fig. 7). This spatial analysis revealed that sampling area (location of the individuals) had a significant effect (ANOVA 1991: $F = 99.4, df = 4, p < 0.001$; 1992: $F = 112.6, df = 4, p < 0.001$; 1996: $F = 696.1, df = 4, p < 0.001$) on the larval otolith growth, with a tendency for growth to decrease going northeast from Area 1 to Area 4. The spatial effect was clearest for the 1991 year class, where there were no differences in otolith growth between larvae from Area 3, Area 4 and the surviving population of 0-group herring (Tukey's HSD test: \( p > 0.05 \)). In the 1992 and 1996 year classes the growth between larvae and 0-group herring differed regardless of larval sampling area (Tukey's HSD test: \( p < 0.001 \)). Corresponding to the observed spatial differences in daily otolith growth, there was also an area effect on larval hatching day and total larval body length (ANOVA Day\(_{37.5}\): \( F = 98.6, \text{df} = 3, p < 0.001 \); ANOVA length: \( F = 15.8, \text{df} = 3, p < 0.001 \)); the earliest hatched and largest larvae tended to be found in the northeastern areas (Areas 3 and 4) (Fig. 8). 4. DISCUSSION Daily otolith growth in NSS herring larvae, as measured at a distance from 37.5 to 137.5 µm from the otolith core after the larvae reached approximate body length of 20 mm, was significantly higher in larvae sampled on the Norwegian shelf in spring compared to the surviving population of 0-group herring sampled in the Barents Sea and fjords the following autumn. These differences in daily otolith growth can be interpreted as a selection for slow-growing larvae, which tend to hatch earlier in the year. Husebø et al. (2009) did not consider larval growth; they simply analysed several potential parameters and found that hatching time had the highest explanatory effect on recruitment, where early hatching in general led to higher survival of larvae. The results of the present study clearly support the conclusions in Husebø et al. (2009), but we also include new knowledge that the high survival in early- hatched herring is not an effect of high larval growth rates, as commonly found in fish (e.g. Takasuka et al. 2003). Observed differences in otolith growth between larvae and 0-group herring coincided with Husebø et al. (2009) both in years where there was early hatching and good recruitment (1991–1992) and in a year with late hatching and low recruitment (1996), suggesting that higher survival in early-hatched and slow-growing larvae may be happening on a regular basis in this population. The spatial analyses demonstrated that the size of the larvae increased towards the northeast, whereas hatching day tended to decrease in the same direction. The largest and earliest hatched larvae, found close to the coast in the north, were characterised by a low daily otolith growth over a distance of 37.5 to 137 µm from the core, which was comparable to that observed in the ground and polished 0-group otoliths collected later in the autumn. This suggests that size, and to a lesser extent growth rate itself, may still be important, as early hatching also may result in earlier metamorphosis despite the slower growth. The slower growth is likely linked to lower ambient temperatures. Particle-tracking model simulations have predicted that larvae that hatch early have a drift route closer to the coast in lower water temperatures than larvae hatched later in the season (Vikebø et al. 2010). Even for larvae hatching later, these model simulations predict that individuals that drift quickly northwards and pass 68° N after 60 d of drift will occupy much colder water compared with those that drift more slowly. The larvae analysed in the present study all showed a rapid increase in daily otolith growth from 62.5 to 112.5 µm followed by a decrease at larger distances from the core. In contrast, in the surviving 0-group population, the daily otolith growth increased more linearly over the otolith size range analysed. The model simulations of Vikebø et al. (2010) show similar differences in temperature trajectories between slow and fast drifting larvae, supporting the notion that daily growth observed in the surviving 0-group is characteristic of fast drifting larvae. The large differences in daily otolith growth found between larvae and 0-group herring of the 1996 year class, even at larger distances from the otolith core, lend support to the hypothesis of high growth in larval retention areas on the shelf. Data from 1996 clearly demonstrated the high daily growth in late-hatching herring on the shelf south of 68° N as late as in June, a level of growth rate well above anything seen in the surviving 0-group. Further support for the effect of early and late hatching on daily otolith growth is provided by a previous comparison of spring spawning herring populations in a coastal system in southern Norway (Berg et al. 2017). Mean width of daily increments at distances between 20 and 170 µm from the otolith core were significantly higher in Landvik herring (peak spawning in May) compared with 2 other populations: Coastal Skagerrak spring spawners (peak spawning in March–April) and NSS herring (peak spawning in February–March), which are mixed in this area. The mean difference in daily otolith growth between the early and late spawners was approximately 0.5 µm at a distance 75 µm from the core, which is at the same level as observed between the larvae and the surviving 0-group herring in the present study. Also, the slow daily otolith growth observed by Berg et al. (2017) in the adult NSS spawning at the southern end of its latitudinal range was comparable to that found in the 0-group population of the present study. There are several reasons why the larvae analysed in the present study may not be fully representative of the total population. In Husebø et al. (2009), particle-tracking model simulations were used to indicate that a significant proportion of the larvae may have drifted out of the survey area in the years 1991 and 1992, suggesting that the early-hatched and/or fast-drifting larvae were underrepresented. This could explain some of the large differences in the otolith growth rate distribution between larvae and the 0-group herring in the present study. Therefore, even though the larvae found in the north may be representative of the early hatching and fast drifters, there is a possibility that larvae had drifted even further north and east, out of the survey area, and these larvae may have had daily otolith growth closer to that observed in the surviving 0-group population. In fact, the tendency of the 0-group to have some raw data measurements of low daily growth outside of that observed in the larvae, especially at distances of 62.5 to 112.5 µm from the core, support the idea that some proportion of the early-hatched larvae already had drifted out of the larval survey area, and were underrepresented in the material. A potential problem concerning the 0-group analysis is linked to the over-representation of fish from coastal rather than Barents Sea nurseries. Ideally, the samples should have been in proportion to the abundances in the nurseries (i.e. more fish from the Barents Sea than the fjords). However, the daily otolith growth observed in the fjords in 1991, 1992 and 1996 are probably representative of the early life history characteristics of the population surviving to the first autumn. This is supported by the observation that in 1991 there were no differences in daily otolith growth between 0-group herring in the Barents Sea and fjords in the south and north. The simulations by Vikebø et al. (2010) also indicated that the drift route of early-hatched larvae was typically closer to the coast and taking the larvae to nurseries in the Barents Sea faster than for late-hatched larvae. Vikebø et al. (2010) stated that the observed differences in drift between early and late hatching is linked to changes in the wind speed and direction. The same wind forces also increase the chances of early-hatched larvae being dispersed into coastal and fjord areas rather than being dispersed westwards on the shelf, which will ultimately lead to early-hatching individuals being the predominant part of the 0-group herring in the fjord nurseries. The possibility that herring from outside of the main NSS herring population contributed significantly to the 0-group population analysed in the present study is considered to be very low. The 0-group trawl sampling was carried out on significant acoustic registrations with size distributions typical for the NSS herring (Husebø et al. 2007), and there are no known local fjord populations in the 0-group sampling areas that could contribute to the observed biomass. The one population that is perhaps large enough to contribute with mixing is the summer–autumn spawners (Husebø et al. 2005), which often overlap with NSS herring during feeding and wintering, but spawn at the northern coast 67 to 69° N in July–August. However, their larvae hatch very late in the year compared with the spring spawners, and would not have reached the same size in the autumn. This is also signified in their daily growth after hatching, which is very slow compared with the NSS herring (Husebø et al. 2005), with increments as low as 1.7 μm at distances up to 100 μm from the core; such patterns were not found in this 0-group material. In addition, their contributions are generally very low; it has been estimated that the recruitment to 0-group (R0) of summer–autumn spawners was below 1% of the recruitment of NSS herring in the 1991–1992 and 1996 year classes (Husebø et al. 2005). The relevance of larval drift to survival of NSS herring was also pointed out by Skagseth et al. (2015). They found that recruitment of strong year classes of NSS herring occurs when there is a rapid transport from the spawning grounds to the northern nursery areas. Strong year classes such as 1950, 1959, 1983, 1991, 1992 and 2002 all had a wide northerly distribution into the Barents Sea (Holst et al. 2004). The mechanism behind the high survival could be a combination of temporal and spatial variation in predation pressure between the coastal drift route and the nursery areas. The significance of hatching time for survival when there is temporal and spatial variation in overlap between predator and prey has also been pointed out by Litvak & Leggett (1992). Higher survival among slow-growing, early-hatched larvae is also found in pollock Pollachius virens, haddock Melanogrammus aeglefinus and walleye pollock Theragra chalcogramma (Fortier & Quinonez-Velazquez, 1998, Lapolla & Buckley 2005, Nishimura et al. 2007) with some studies showing that selective predators may choose the largest individuals (Litvak & Leggett 1992, Pepin et al. 1992, Takasuka et al. 2007). The results of the present study contradict the growth-rate hypothesis, which combines feeding success and predation, and states that fast-growing individuals have a higher probability of survival compared to slower growing individuals (Campana 1996, Meekan & Fortier 1996, Hare & Cowen 1997, Payne et al. 2013). As suggested in Husebø et al. (2009), selection in NSS herring takes place for the earliest hatched and consequently the slowest growing individuals, which arrive early in the nursery areas prior to the increased predator levels developing northwards during spring warming. In general, it is important to acknowledge that survival in fish larvae is influenced by several factors. The spawning of NSS herring and the larval drift seems to be adapted to the delay in the bloom with increasing latitude of 37 d within the spawning habitat of NSS herring (Vikebø et al. 2012); clearly a lack of overlap with prey for larvae may be very important. Most larval mortality likely occurs in the first couple of weeks, and here a match between elevated prey and growth rates is probably being selected for. The high mortality shortly after hatching is clearly demonstrated by the lack of correlation between early larval abundance indices and the abundance of age-3 recruits of the same year class (Sætre et al. 2002a). Still, it is important to emphasize that the present study focused on mortality from the post-larval stage (20 to 30 mm body length) to the 0-group stage. Sætre et al. (2002a) demonstrated that abundance at the post-larval stage explained about 40% of the recruitment until age 3, whereas abundance at the 0-group stage explained about 80%. This suggests that there is still high mortality at the post-larval stage, and our hypothesis is that predation is the main reason for the lack of survival until 0-group stage. Predation is a complex and poorly understood factor (Pepin 2016). At the late larval stage, mortality caused by invertebrates decreases significantly, whereas the predation pressure from planktivorous fish increases (Pepin 2016). Although there is no conclusive evidence, there are some planktivorous fish that could potentially prey heavily on the NSS larvae given an overlap in time and space, such as blue whiting *Micromesistius poutassou* (Monstad 2004), salmon *Salmo salar* smolts (Haugland et al. 2006), mackerel *Scomber scombrus* (Skaret et al. 2015), and saithe *Pollachius virens* (Bjørke et al. 1991), in addition to herring itself, which may contribute to high levels of cannibalism (Holst et al. 1997, Dalpadado et al. 2000, Prokopchuk & Sentyabov 2006). One common feature related to the occurrence of important predators in the drift route of the herring larvae is that it is often restricted to a relatively limited period due to the migration patterns and behaviour of the predators. Therefore, in general, early hatching and fast larval drift to the Barents Sea or into the fjords may reduce overlap with the main potential predators. On their feeding migration from spawning grounds to the west of Ireland, mackerel enter the Norwegian Sea and the Norwegian coastal area in June–July (Nøttestad et al. 2016). Blue whiting also migrate from the main spawning area southwest of Ireland to feed in the Norwegian Sea in the summer. Both mackerel and blue whiting are found along the Norwegian shelf in areas and times overlapping with herring larval drift (Ulne et al. 2012, Skaret et al. 2015, Nøttestad et al. 2016). Husebø et al. (2009) used purse catch data on saithe to demonstrate that abundance of this stock along the drift route was high, with increasing activity in spring related to the warming of coastal waters. They demonstrated that the saithe tended to aggregate in schools, presumably actively feeding much earlier in the southern part of the distribution area than in the north, and herring larvae from an early hatching would have drifted past the main areas during periods of high feeding activities of saithe. This is comparable to the delay in phytoplankton blooms occurring northwards along the coast in spring (Vikebø et al. 2012). Puffins *Fratercula arctica* are also important predators that, during certain times of year and in some years, can consume large amounts of herring. In fact, it has been suggested that the year class strength for the NSS herring is determined after most of the herring larvae have drifted past the puffin colonies in July–August (Sætre et al. 2002a), so earlier arrival in the Barents Sea nurseries and reduced overlap with the puffins would be advantageous for the herring. Anker-Nilsen (1992) suggested that the puffins may constitute approximately 20% of the total consumption of 0-group herring. High survival of a year class until 0-group stage may not necessarily lead to high recruitment into the fishery as adults, despite a significant relationship between the number of 0-group fish and recruitment. Growth of the 0-group until the adult stage may not follow larval growth, and the selection pressure related to size may vary accordingly. Several authors argue that variable mortality during the juvenile stage may account for a considerable part of the observed variability in recruitment (Sissenwine 1984, Smith 1985, Sparholt 1990). The mortality of NSS herring in the nursery areas is also of importance for recruitment to the spawning stock. To illustrate this, survival during the whole juvenile period from 4 mo to 3 yr was estimated to range between 16 and 19% for the 1983, 1989, 1990 and 1991 cohorts, while for the 1984, 1985, 1988 and 1993 cohorts it was close to 0%, and close to 10% for the 1992 cohort (Barros & Toresen 1994, 1998, Barros et al. 1998). In the Barents Sea, Atlantic minke whale *Balaenoptera acutorostrata* (Lindstrøm et al. 2002), cod *Gadus morhua* (Johannesen et al. 2012) and harp seal *Pagophilus groenlandicus* (Johansen et al. 2004) are considered to be among the most important predators of juvenile herring. However, minke whales also feed heavily upon herring in coastal areas of northern Norway, especially when the herring produce strong year classes (Haug et al. 1993). Cod consumption on herring varies with the size of the capelin stock, and it has been suggested that cod is an important predator of herring juveniles in years with poor capelin recruitment (Barros et al. 1998, Godiksen et al. 2006), but it is probably not an important predator along the coast. ### 5. CONCLUSIONS The present study has demonstrated that the earliest hatched larvae found in the north and close to the coast in May, and the surviving population of 0-group NSS herring during autumn, are characterised by similar slow daily otolith growth at comparable sizes, i.e. after reaching a body length of approximately 20 mm, at a distance from 37.5 to 137.5 μm from the otolith core. We argue that this indicates that early hatching and/or fast drift is important for larval survival. We suggest that increasing temperatures may have an indirect effect on recruitment of NSS herring, by inducing earlier spawning and hatching time, and that the potential mechanism behind high larval survival is most likely temporal and spatial variation in predation pressure between... the larval drift route and the nurseries in the fjords and the Barents Sea. The occurrence of important predators like mackerel, blue whiting, salmon, saithe, herring (cannibalism) and penguins along the drift route of herring larvae is often restricted to a relatively limited period due to their migration pattern. By hatching early and/or drifting fast, the larvae may tend to avoid overlap with these predators compared with those that hatch later. Hence, selection may take place for the earliest hatched and subsequently slowest growing individuals arriving early in the nursery areas prior to the increased predator levels developing northwards during spring warming. Size, and to a lesser extent growth rate, may still be important, as early hatching also may result in earlier metamorphosis despite their slower growth. LITERATURE CITED Berg F, Husebø Å, Godiksen JA, Slotte A, Folkvord A (2017) Spawning time of Atlantic herring (Clupea harengus) populations within a restricted area reflects their otolith growth at the larval stage. Fish Res 194:68–75 Pepin P, Shears TH, Delafontaine Y (1992) Significance of body size to the interaction between a larval fish (Mal-lotus villosus) and a vertebrate predator (Gasterosteus aculeatus). Mar Ecol Prog Ser 81:1–12 Sparholt H (1990) Improved estimates of the natural mortality rates of nine commercially important fish species included in the North Sea multispecies VPA model. J Cons Cons Int Explor Mer 46:211–223 Toresen R, Østvedt OJ (2000) Variation in abundance of Norwegian spring spawning herring (*Clupea harengus*, Clupeidae) throughout the 20th century and the influence of climatic fluctuations. Fish Fish 1:231–256 Vikebø FB, Husebø Å, Slotte A, Stenevik EK, Lien VS (2010) Effect of hatching date, vertical distribution and inter- *Editorial responsibility: Susana Garrido (Guest Editor), Lisbon, Portugal* *Submitted: September 1, 2017; Accepted: June 27, 2018* *Proofs received from author(s): September 2, 2018*
Rupkatha Journal On Interdisciplinary Studies in Humanities An Online Open Access Journal ISSN 0975-2935 www.rupkatha.com Volume VI, Number 3, 2014 Chief Editor Tirtha Prasad mukhopadhyay Editor Tarun Tapas Mukherjee Indexing and abstracting Rupkatha Journal is an international journal recognized by a number of organizations and institutions. It is archived permanently by www.archive-it.org and indexed by EBSCO, Elsevier, MLA International Directory, Ulrichs Web, DOAJ, Google Scholar and other organizations and included in many university libraries. 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Female bodies in cross-border feud have always been subjected to abjection for the greater religio-political need. The bodies of women have proved to be useful mediums to transfer symbolically messages of power, victory and supremacy. Violence perpetrated on these bodies not only metaphorically asserts male superiority, but also serves as an effective platform to terrorize people. Degrading the female bodies also signifies the extermination of a particular community, both by destroying the honour and impregnating them with the seeds of a foreign community. Reading Jean Franco’s account of debasement of female bodies in the war across USA-Mexico border and the partition narratives based on the Indo-Pakistan front, as well as taking into account the contemporary scenario of Islamic terrorism, this paper aims to look at the ways in which women’s bodies are violently debased, and analyse the symbolisms of such abjection against the backdrop of border-wars. [Keywords: Border, partition narratives, Islamic terrorism, female bodies, abjection.] Introduction “...when the taboo against harming others is broken, there can be no limits, no social pact.” (Franco 1) Franco in her 2013 book *Cruel Modernity* analyzes the various forms of cruelty that has begun to define modernity in Latin America. Though focused only on the discriminating atrocities committed across the USA-Mexico border, her reading is an echo of border politics all around the globe. Border exists, whether visible and physical or invisible and imaginary, because there is an ‘other’. It differentiates race, religion, ethnicity, community, nationality, language and even gender. Franco’s extensive research reveals that the only possible way modernity can negotiate with such varied borders is through an extreme form of violence which amounts to a complete dehumanization of both human body and psyche. The violence inflicted on human beings, in such cases, leads to a debasement of the human body and reduces it to an animalistic status. The human body, subjected to beatings, curses and other forms of humiliations, loses its subjectivity and becomes synonymous to a non-human existence. Franco examines the conditions under which extreme forms of cruelty become “the instrument of armies, governments, and rogue groups” and seeks to answer the question, “Why, in Latin America, did the pressures of modernization and the lure of modernity lead states to kill?” (Franco 2) This is not to say that Franco considers cruelty as a newly emerging phenomenon. She is not blind to the fact that neither cruelty nor its exploitation is new. However, it is the lifting of the taboo against harming others that concerns her thesis. She explores how “the acceptance and justification of cruelty and the rationale for cruel acts” (Franco 2) has become a major feature of modernity. The scenario that she paints is a universal one – be it across the USA-Mexico border or the India-Pakistan border. The root cause of such barbarism across multiple forms of borders can be pinned down to the internalization of border in human psyche. Border denotes difference and difference is a natural phenomenon, since the world as it was created was not a homogeneous one. However, the differences of race, religion, ethnicity, language has led to an utmost intolerance towards the other calling for its cruel annihilation. The hatred towards the other has been nurtured to such an extent that human conscience no longer recognizes cruelty as an act amounting to crime. The involvement of state apparatuses in further endorsing this hatred and its participation in the game of brutality deprives humans of their rights in such a manner that “no act committed against them could appear any longer a crime” (Agamben, qtd. Franco 4). ‘Cruel Modernity’ and the Female Body Among other forms of brutality which constitute ‘cruel modernity’, the treatment of the female bodies in cross-border politics is the most grotesque and barbaric. The female body is a site of numerous conflicting and contesting claims. It is a site to assert male supremacy; it is simultaneously a site where the symbolic extermination of an entire community or race can be carried out; it is also a site which bears the burden of honour. This honour once again is not singularly of the woman’s. The honour of her family, the honour of the race and ethnicity to which she belongs are all manifested on her body. The female body, therefore, is a vulnerable site – a site whose violation can symbolically violate an entire community, and a site whose protection is mandatory to maintain the purity and integrity of the community, even if that protection comes at the cost of her life. This paper studies this complex reading of the female body and how it is used to manipulate cross-border politics. Through a comparative reading of instances of abjection of the female body from Franco’s Cruel Modernity and literary examples from the Indo-Pakistan border this paper attempts to show how two widely different border spectrums resort to a similar brutal treatment of the female body with an aim of turning it into an abject to assert various forms of male supremacy in their own individual ways. The Concise Oxford Dictionary defines abject as “Brought low, miserable; craven, degraded, despicable, self abasing” and it describes abjection as a “state of misery or degradation.” While describing how abjection is expressed, Samantha Pentony in her article ‘How Kristeva’s theory of abjection works in relation to the fairy tale and post colonial novel: Angela Carter’s The Bloody Chamber, and Keri Hulme’s The Bone People’ comments that “[R]eligious abhorrence, incest, women's bodies, human sacrifice, bodily waste, death, cannibalism, murder, decay, and perversion are aspects of humanity that society considers abject” (Pentony 1; italics are mine). This paper traces how women’s bodies in being subjected to the politics of abjection become a means of proclaiming male supremacy in conflicts across all kinds of borders – whether geographical, political, racial, or most importantly, gender. Julia Kristeva put forward her theory of abjection in *Powers Of Horror: An Essay on Abjection* (1982) where she identifies that we first experience abjection at the point of separation from the mother. This idea is drawn from Lacan’s psychoanalytical theory which underpins her theory of abjection. She identifies that abjection represents a revolt against that which gave us our own existence or state of being. For Kristeva, the corporeal link between mother and child is the most fundamental abjection of all, initiating the logic upon which all other forms of abjection are predicated and paving the way for the child’s entry into the symbolic. This, for Kristeva, is why language is a masculine preserve and why femininity – and particularly maternity – is tainted with the abject. According to her, abjection describes the ambivalent process of subject formation in which elements that the self cannot assimilate are expelled, disavowed and designated repugnant. Her model of the Abject outlines a conflict in gender between patriarchal signification and the female imaginary and explains female oppression as an inability to cast off the internalization of the mother. Taking her cue from Kristeva, Barbara Creed writes: “The place of the abject is where meaning collapses, the place where I am not. The abject threatens life, it must be radically excluded from the place of the living subject, propelled away from the body and deposited on the other side of an imaginary border which separates the self from that which threatens the self. (Creed 65; italics are mine) Besides political, racial, communal, ethnic and linguistic borders, women have to confront what is probably the most unaccounted but the most diabolic border – the border of gender – where women are seen as men’s ‘other’ and, thus, are separated out in heinous ways of all kinds. **Gender Borders: Raping and Honour Killing** Franco in her introduction to *Cruel Modernity* makes a brief distinction between the torture wreaked upon men and women in the combat across political and racial borders in Latin America. She writes: “Debasement that included curses, beatings and all kinds of humiliation were practiced on both sexes, but in the case of women it was taken to extremes, as the victims were submitted to not only rape and even worse but were also insulted as whores. Moreover, rape was seldom the sexual act *tout court* but often involved the insertion of arms and sticks into the vagina.” (Franco 14) The fact that women are plagued and degraded further through acts which involved their genitalia clearly marks this border between genders. The female bodies are subjected to further debasement simply because they are of the opposite sex. This added sexual injury to the female bodies, which degrades them to an almost non-human existence, apart from the usual physical brutality meted out on men and women alike, is a global phenomenon in any kind of cross-border encounter. On a first reading, rape is seen as a crucial and symbolic masculine weapon to declare male supremacy, but there is more to that. Women, by virtue of their ability to procreate, ensure the progress and immortality of the community to which they belong. The female bodies, therefore, are sexually attacked to symbolically affect the entire community. Since women are the carriers and preservers of the question of ‘honour’ and ‘purity’ of a community, they become the easy target of the opposing group who want to degrade physically and psychologically the community on the other side of the border. The female bodies, as a result, become sites for a two-fold politics of annihilation and contamination. Raping and implanting the seed of a different community in a female body symbolizes an attempt to ‘contaminate’ the parent race of the woman, as the product of that act will be a ‘hybrid’ offspring of two racially different groups. If raping symbolizes the endeavour to destroy the purity of a race, the episodes of stakes thrust through female genitalia symbolizes the will to prevent a population’s reproduction through complete sterilization. From this two-fold politics where the bodies of the women are used to ruin a particular race emerges another socio-political stance with the women as the focal point – the politics of ‘honour killing’. If raping and abusing the sexual organs of women was a common occurrence in the genocidal wars in Peru and Guatemala, ‘honour killing’ was seen in its extreme form during the communal violence that accompanied the 1947 partition of the Indian sub-continent. The precise reason for which men sexually violated women of other communities, women were killed by the male members of their own families or community. Lest they are raped and, thus, destroy the purity of the community, women were killed to preserve both their honour and in turn the honour of their communities. The female bodies are, therefore, vital instruments in cross-border politics which could be used to either cause or prevent destruction. The next section of the paper deals with each of these politics of the female body through literary representations from the India-Pakistan border combat and through Franco’s documentation from the USA-Mexico border. Raping to Assert Male Supremacy To begin with, female bodies are sites where men could easily assert their supremacy by forcing the former to a sexual subjection. While Franco shows instances where women were sexually debased by men of other communities, Saadat Hasan Manto shows women being mercilessly raped by men of both their own communities and other communities, thus, highlighting the gender border that exists between these two opposite sexes. A reading of the two stories ‘Colder than Ice’ and ‘The Return’ as companion pieces would further elucidate this. Set in the Indian side of the border during the communal violence of partition, the first story is about a Sikh named Ishwar Singh. Amidst the tumultuous time of riots and violence, Ishwar Singh was busy looting the empty Muslim shops and homes. During one such loot he broke into a Muslim home where there were seven people, six of them men and one a woman. Ishwar Singh later recalls to his wife: “...there were seven people in there, six of them men whom I killed with my kirpan one by one...and there was one girl...she was so beautiful...I didn’t kill her...I took her away.” (Manto 19-20) While the only ultimate violence that he inflicted on the men was death, the girl, who by this time appeared fainted, was taken away to be sexually violated before being killed. Ishwar Singh could have straight away “slashed her throat” (Manto 20) but he did not. This act of raping the girl is an additional form of violence that emerges from the border that exists between man and woman and, hence, something which men were exempted from. In the second story ‘The Return’, a Muslim girl Sakina gets detached from her father in the mass exodus across the newly created geo-political border that divides India from Pakistan. Her father requests the Pakistani military to rescue her. The Muslim army personnel promises rescue but with that promise of rescue repeatedly rapes her till she almost drops dead. Manto’s sensitive treatment of the subject of brutality on women reveals that apart from communal and racial borders, women bore the brunt of gender border as well. Men seized the opportunity of a turbulent political time to devalue female bodies irrespective of their race or religion, and derived a masochistic pleasure in asserting their sexual supremacy over women. Both these stories are prominent reflection of the events in another part of the world at another time. The story ‘Colder than Ice’ bears strong resonance with the raping of dead that Franco talks about in her book. Franco brings up instances from the testimony of ‘El Brujo’ before the Truth and Reconciliation Commission of Peru where a woman was raped after her throat had been cut and she was next to dead and unable to satiate the sexual greed of the men. In Manto’s story, Ishwar Singh rapes the fainting girl only to realize that she was dead. These two similar accounts reveal a horrific side of cross-border politics, where not only were female bodies seen as objects to be exploited but also as something which could be denied respect even in death. This denial of respect even in death is explicitly recorded in a number of partition novels: While Khushwant Singh’s novel *Train to Pakistan* (1956) describes events where train full of mutilated female corpses arrive to India from Pakistan, Bapsi Sidhwa’s novel *Ice-Candy Man* (1988) records episodes of sacks full of female breasts arriving to Pakistan from across the border. These passages show the utter abjection of the female bodies which “places the victim outside the bonds of the human” (Franco 77). Franco terms this “extreme masculinity” (Franco 78) which in effect is a “rage against the womb” (Franco 78). She goes on to write that “rape not only abolishes any claim by the victim to be in the same ‘human’ category as the rapist, who is confirmed in his supremacy, but also annihilates woman as the feared other” (Franco 78). This male supremacy is asserted not only across racial and communal borders but also across gender borders as is evident from the second story of Manto mentioned above. Sakina in ‘The Return’ is raped so many times that she internalizes the act of rape in her psyche. Later when the exhausted body of Sakina is brought into the camp hospital and the doctor asks her father to open the window, the mere word ‘open’ forces the otherwise listless body to move and open her dress and expose itself for the rape: “The doctor looked at the prostrate body and felt for the pulse. Then he said to the old man, pointing at the window, ‘Open it.’ The young woman on the stretcher moved slightly. Her hands groped for the cord which kept her shalwar tied around her waist. With painful slowness, she unfastened it, pulled the garment down and opened her thighs.” (Manto 41) Her action shows the extreme cruelty to which male barbarism can subject a woman to. Sakina was of the same community as the military personnel. In spite of that she was treated as an abject female body. The only difference being that they did not kill her since, sharing the same religious belief, it was not necessary for the men to kill her as a symbolic extermination of her community. ‘The Return’ is a reflection of the way state apparatuses such as military wreck havoc on the female bodies without any fear of punishment. Franco records instances where the army is instructed to brutally wipe out the indigenous people “for women as bearers of tradition must be incapacitated or destroyed in the cause of creating a new Guatemala...without ethnic difference” (Franco 83-84). This is what Barbara Creed meant while stating that the abject ‘other’ is radically excluded since it threatens the ‘self’. Franco’s instance is an echo of Kelly Oliver in Women as Weapons of War (2007) where the latter says that “military practices...normalize violence, particularly in relation to women and sex” (Oliver 8). Armed with impunity, the state machinery such as the military has recurrently pushed down the women to the basest level treating their bodies as commodities to be destroyed. The involvement of the state apparatus deprives the victims of any legal help and leaves them with no other option but to be continually exploited and degraded. All these acts of denigration identify the women as inferior and, thus, recognize the triumph of male sovereignty. Debased Female Bodies and Destruction of a Race “Women have been associated with the downfall of man since Eve supposedly tempted Adam with forbidden fruit” (Oliver 9). In other words, female bodies can be used to indirectly inflict damage on their male counterparts. Raping the women is not merely an act denoting the exultation of male superiority over female inferiority. It is also emblematic of destroying the purity of a race. Due to the biological construct of their bodies, women have to bear the consequence of polluting their race or ethnicity. It is precisely because of this reason, that the fates of the women who survived cross-border rapes were tainted with shame and humiliation. Both in Franco’s research on the Peru-Guatemala front and in those of Urbashi Butalia, Ritu Menon, Kamala Bhasin and others on the India-Pakistan front, there is an identical reproduction of the destiny of the raped women. Since the exploitation of their bodies contaminated their community, they were relegated to the fringes of the societies as outcast. Most of them were disowned by their families as well, since accepting them would outcast the entire family. Franco writes: “For the victim who survived, the sexual act was transmuted into unbearable and unforgettable torment. Its devastating effect went beyond the individual, for it attacked the family as the very basis of society, inducting feelings of isolation and desperation. Women who survived wartime rape often suffered physical damage and were left isolated.” (Franco 78) A similar case of isolation was faced by the women who were raped amidst the communal violence induced by the partition. Kamala Bhasin and Ritu Menon in their book *Borders and Boundaries: Women in India’s Partition* (1998) describe the bleak scenario post the passing of ‘The Abducted Persons (Recovery and Restoration) Act’ in 1949. Among the enormous number of women who had been abducted and raped many were recovered either as pregnant or with the child of the rapists. Their families, who were more concerned both with their notion of honour and the fear of being treated as an outcast than with the fate of their women, refused to accept them. As a result these homeless women remained at the mercy of camps and other women development cells to arrange some sort of livelihood for them. To counter what was its symbolic contamination, the community, thus, out casted the so called ‘bearer’ of that impurity. In this attack and counter-attack of destruction and preservation of purity, the bodies that were wasted were those of the women. They suffered not only physical abjection but also psychological abjection. Not only were they debased to an animalistic existence by the physical tortures, but also suffered mental degradation by the treatment of the society. The women were not subjected to rape alone. The act of rape was often accompanied by mutilation and decimation of the female sexual organs. The female bodies, as said before, are sites which endorses multiple layers of politics. If through the acts of rape, they were used as a setting for the proclamation of male supremacy and defilation a community, they were also used as an area where the symbolic annihilation of a community was carried out. Franco records events where the abjection of women was maximized by forcing them to be on their hands and legs like animals and shooting them by placing the gun in the anus or vagina. Such defilation of the bodies was to ensure that the victims no longer resembled human beings. This politics of abjection was seen in a different way in the context of the partition of India where the breasts of female bodies were chopped off. *Train to Pakistan* as mentioned before records the gory details of trains coming to India from Pakistan with bodies of women whose breasts have been slashed. Set in the border village of Mano Majra during partition, Khushwant Singh’s historical novel records how the otherwise peaceful village turns into a battlefield when a train from the other side of the border arrives carrying the bodies of dead Sikhs. While the male bodies were left aside after being murdered, the breasts of the female bodies were slashed after the women were killed. One finds description of similar episodes in Bapsi Sidhwa’s *Ice-Candy Man*, the difference being this time it is the Muslim women whose bodies have been mutilated. Ice Candy Man reports to his friends that a train from Gurdaspur has arrived in Lahore filled with murdered Muslims. He shouts, “Everyone in it is dead. Butchered. They are all Muslims. There are no young women among the dead! Only two gunny-bags full of women’s breasts” (Sidhwa 149). This act of violence against Muslim women spurs him to inflict violence on Hindu and Sikh women. He exclaims, “I want to kill someone for each of the breasts they cut off the Muslim women” (Sidhwa 156). He satiates his appetite for revenge by kidnapping Ayah and forcing her to prostitute her body. What is evident is that female bodies are the sole abject sites for carrying out attacks and revenges as if cross-border feud can only be successfully carried out by degrading the female bodies. Such acts of either mutilating the female bodies by cutting off particularly the breasts or destroying the genitalia are symbolic acts of terminating the very life-spring of a community. In Shauna Singh Baldwin’s *What the Body Remembers* (1999) Bachan Singh beheads Kusum, his daughter-in-law, lest she is raped by the men of other communities. Her husband Jeevan, who is unaware that his father has beheaded his wife, is surprised that she has not been raped before being murdered: “[T]o cut a woman apart without first raping – a waste, surely. Rape is one man’s message to another: ‘I took your pawn. Your move’” (Baldwin 576). The bodies of the women are the sole medium through which men could pass on their message of supremacy to each other. Turning the female bodies as mediums to transfer messages of power and supremacy commoditize the female body on another level and further debases them by denying them their human subjectivity. A short while later Jeevan receives the ‘message’ that was intended for him. “Kusum’s womb, the same from which his three sons came, had been delivered. Ripped out. And the message, ‘We will stamp your kind, your very species of existence. This is no longer merely about izzat or land. This is a war against your quom, for all time. Leave. *We take the womb so there will be no Sikhs from it, we take the womb, leave its shell.*’” (Baldwin 576; italics are mine) Kusum, therefore, faced double abjection. She was killed by her father-in-law lest “seeds of foreign religion” (Baldwin 586) were planted in her womb; and her womb was ripped apart as a symbolic act of exterminating the entire Sikh community. Like destroying the womb, episodes of shooting the vagina or thrusting objects through it, that Franco records, are symbolic acts of castration, which figuratively prevents a community’s reproduction and regeneration. Similarly, chopping of the breasts, which are the repository of nourishment for the babies, denotes depriving the future generation of the required nourishment for life. Freud in *The Interpretation of Dreams* analyzes one of his dreams where he saw a woman making dumplings in a kitchen. In his analysis his dream is one of wish fulfillment of the basic need for food and love, which he claims come together in the mother’s breast. The mutilation of female breasts, therefore, also signifies depriving the entire population of their basic requirement of food leading to their symbolic death. In the cross-border politics where the (baseless?) need arises to destroy a population, the female bodies become representational locales where symbolic extermination and defilation of a community can be carried out. **Female Bodies as Sites of Honour** The female bodies are, thus, appropriate planes to assert male ascendancy as well as to carry out figuratively the violation and contamination of a community and its complete elimination. Such ends are achieved only through an abjection and dehumanization of the female bodies. However, they are also used to counter these very attempts of annihilation and defilation. The question of ‘honour’ as something sacred is embedded in the tradition of India. Honour, once again, works on multiple levels – individual honour, family honour, community honour, racial honour, ethnic honour etc. On women is bestowed the responsibility of preserving this honour. The violation of their bodies dishonours not only their individual self but their families as well as an entire community. Hence, in order to prevent any such loss of honour, the male sovereign heads took recourse to the killing off the women of their families. This act of killing the women of one’s own family to save their honour and, in turn, the honour of the family, from being polluted by men of different communities gets the title of ‘honour killing’. The pathos of this act is portrayed in Baldwin’s *What the Body Remembers* where to save the honour of Kusum from being violated at the hands of Muslims, her father-in-law beheads her with a kirpan. He does not kill Revati Bua or Gujri since both were old and passed child-bearing age so no man would feel dishonoured if they were raped. However, since Kusum’s body still possessed the capability of extending the community, it should not be ‘unjustly’ used to pollute the community’s purity. Urvashi Butalia’s archival work *The Other Side of Silence: Voices from the Partition of India* (2000) narrated such true incidents where Sikh and Hindu men killed the women and female children of their families without any hesitation so as to save their ‘honour’ from the approaching mobs of a ‘foreign religion’. ‘Honour killing’ is almost an oxymoron. The woman is left to choose from two options with similar consequences: either to be raped and face a literal death or a symbolic one through isolation; or to ‘honourably’ die at the hands of a male relative. Two significant politics is involved in this entire theory of killing for honour. First, the concept of ‘honour killing’ arose with the assumption of the female body as sites of honour, or as Baldwin’s protagonist Roop observes “as bearers of blood, to do what women are for” (Baldwin 587). This doing is to prefer death to dishonour which is the characteristic of “good-good women” (Baldwin 587). This is in opposition to the consideration of female bodies as ‘surplus’ (that is, easily available in large number to be preyed upon), an argument reiterated by Franco as well as evident from the partition narratives discussed above. So there is a contradictory pull between female bodies as a storehouse of honour and the female bodies as ‘wasted’ and ‘abject’. Strikingly, in both the stands what is common is the killing of the female bodies. Whether in the garb of ‘honour killing’ or in an attempt to eliminate a population, female bodies were seen as objects which could be, without inhibition, condemned to violent annihilation. Both in the act of destroying the purity of a race and preserving it, the female bodies, therefore, were at the receiving end of violence and abjection. Second, whether in the form of ‘honourable’ death or cruel abjection, female bodies are exterminated at the hands of the men. Thus, in both the forms of killing, it is an assertion of male dominance where the women either have no agency, or, their voices are deliberately stifled. Contemporary Scenario: Islamic Terrorism The debasement of female bodies for the above mentioned reasons is a potent weapon in the contemporary scenario of Islamic terrorism as well. The Islamic militant group ISIS has used sexual violence against women as a means of ethnic cleansing in its campaign against the Yazidi minority in northern Iraq. Since women symbolize culture and group, systematic rape and other forms sexual violence can serve the goal of ethnic cleaning by eroding the way of life of a community rather than displacing or killing all members of the group. The fabric of societies, communities, and families can be destroyed by sexually violating women and leaving them alive. Such was the case in Bosnia where Serb fighters committed systematic rape against tens of thousands Muslim women as a part of their strategy of ethnic cleansing, including forced pregnancies to produce children of the perpetrator’s ethnicity. It was also the case during the genocide in Rwanda where Hutu militiamen employed rape, mutilation and other sexual violence to humiliate Tutsi women, transmit HIV, and prevent them from having Tutsi children. In a similar manner, ISIS employs sexual violence against Yazidi women as a significant part of their campaign of ethnic cleansing against the Yazidi community as a whole. The abjection of female bodies, however, does not merely manifest itself in violence of different kinds. The bodies of the women also serve as the sites on which extremist agendas are imposed. The ISIS militant group has a female brigade to teach women their proper place in the society. The very fact that women under the ISIS regime needs to cover up her entire body and cannot step out of the enclosed interiors of home show a different kind of debasement of the female bodies. This is, however, not new. Women at various points in Islamic history have been denied the freedom of the body. During the sectarian violence of 2008, when Iraq was under the US occupation, a graffiti on the walls in the city of Basra threatened, “Your makeup and your decision to forgo the headscarf will bring you death” (Susskind 2). In response to the repression imposed on them, Iraqi women mobilised in unprecedented ways. For instance, the Organisation of Women’s Freedom in Iraq (Owfi) “created a network of underground safe houses for women fleeing violence at home and in the streets” (Susskind 2). The women of Owfi also spoke out against policies that created sectarian divisions and fuelled gender-based violence. The ISIS militants are using rape and brutality to control women who have not stopped mobilising since the US occupation. Women living under ISIS control have been seized from their homes and raped. They have been ordered to cover themselves fully and stay in the house. These are systematic attempts to control the female body and, therefore, in turn, curb any kind of female independence. While in 2008 under US occupation women were not even safe at home, especially after ‘honour killing’ was endorsed as a religious duty for families to police women’s behaviour, in the current scenario in communities occupied by Isis, fighters have kidnapped women from their homes, telling their families that these attacks are justified by a ‘sexual jihad’. If ISIS aims at using female bodies to optimize terror in the minds of civilians, another militant group, Boko Haram, (which originated in Nigeria and literally means ‘against western education’) aims at using women to establish a complete Islamic authority. Girls and women abducted by the Nigerian Islamist group Boko Haram have described life in captivity which includes forced marriage and labour, rape, torture, psychological abuse and coerced religious conversion. More than 500 women and girls have been seized and held in militant camps since 2009. The single biggest abduction was of 276 girls from a school in Chibok in April. The majority of abductions by Boko Haram were of Christian women and girls, threatened with death or violence if they refused to convert to Islam. Religious conversion of the women, who are the fountain head from which new life springs, signifies the complete extermination of a particular religious community. Raping them and forcefully marrying them serves both the purposes of terrorising the non-Islamic civilians who would be threatened by such acts to evict the state, and of symbolically annihilating the non-Islamic communities by depriving them of the women who are the carriers of new generations. The degradation of female bodies, therefore, is an outcome of multiple layers of political and religious conflicts where the women could be effectively used as pawns to acquire the desired results. Conclusion The UN Declaration of the Elimination of Violence against Women (VAW) states that “violence against women is a manifestation of historically unequal power relations between men and women” and that “violence against women is one of the crucial social mechanisms by which women are forced into a subordinate position compared with men”. Some examples of VAW include rape, domestic violence, sexual harassment, female infanticide, prenatal sex selection, honor killings, dowry violence, female genital mutilation, and forced marriage. Apart from fulfilling the purpose of subordination, female bodies are also degraded to achieve other greater goals. Whether death without any other forms of physical torture, or death preceded by abject humiliation, female bodies are used as abject commodities to assert various forms of supremacies across different forms of borders. Across the gender border they are sites to proclaim male sovereignty, either through rape or through honour killing. Across racial and communal borders they are used to achieve two ends - to defile and pollute an entire community by implanting within the female bodies the seed of the rape, and to symbolically restrain a population from further reproduction by the violent destruction of the female sexual organs. And within a community the female bodies are sentenced to death for the larger cause of maintaining the honour of the family and the community. Whether it is Guatemala and Peru, or India and Pakistan, or the contemporary context of Islamic terrorism in Iraq and Nigeria, abjection of female bodies in various patterns is the major means of negotiating cross-border encounters. The bodies of women endorse multiple layers of politics to either help in achieving male superiority, or to aid the triumph of one race over the other in the combat across racial and communal borders through their abjection. Works consulted: Deblina Hazra is a final year M. Phil student at Jadavpur University, Department of English. She has completed her graduation and post-graduation from the same department. She has published in the *Muse India* and other journals. She has also presented papers at several national and international conferences. Her areas of interests are Nineteenth Century literature and culture, South Asian literature and Indian Literature in English.
Abstract: The visual arts still suffer low reception and patronage in contemporary Nigeria as a result of an ongoing oriental stereotypical representation in Nollywood, the media and churches. This paper interrogates this problematic to address the subtle subversion of the arts that continues to grossly impede its development. Adopting the analytical tools of Content Analysis, this paper traces the origin of anti-art propagandism to missionary and colonial activities in Nigeria and establish its continues adverse propagation in Nollywood and modern churches. Findings from this paper conclude that the portrayal of visual arts in Nigerian movies as the instrument of dark practices and the further condemnation of the arts in churches as symbols of heathenism is responsible for the disdain towards the arts in contemporary Nigeria and responsible for its poor reception and patronage. The research contends, therefore, that both the media, Nollywood and churches must rethink their oriental fantasies about the arts because until that happens the anti-art culture inscribed in the consciousness of many Nigerians will continue to impede artistic progress and visual/aesthetic illiteracy. Keywords: orientalism; Nollywood; stereotypes; reception; contemporary; art; patronage; Nigeria I. Introduction Although art has made considerable inroads in Nigeria, the discipline is still shrouded by negative imagery and disdain. This disregard for the visual arts in contemporary Nigeria is akin to a negative cultural consciousness inscribed in the fabric of our collective existence. Visual arts in contemporary Nigeria experiences poor reception, patronage and appreciation and the cause of this contemporary menace can be traced to media activities, Nollywood fantasies and modern Churches. Nollywood refers to the brand of home movies produced in Nigeria defined by dramas that focus on Nigeria lifestyle, culture and peoples as well as contemporary existentialism inspired by global multiculturalism. The activities of the aforementioned with regards to their portrayal of the arts can be equated with Orientalism. I deploy the term Orientalism fully aware that the context of its construction by Edward Said is rooted in his deconstruction of colonialism and the West’s relation to the East (that is the Orient and Occident relationship). But in a broader context, Edward Said classifies Orientalism as a system of representation used in constructing and imaging the ‘Other’ (imperial classification and categorisation of all cultures outside the Western mainstream). It is this representational context of the concept that is employed to deconstruct the clandestine attacks on the arts in Nollywood and the mass media through a systemic subversive and derogatory representation. In his widely read book Orientalism 1978, Edward Said argues that the most dangerous weapon used during colonial subjugation is the misconstrued classification of colonised cultures through a system he described as Orientalism - a framework of representation developed as lens or compass through which to view the colonized to force them into an inferior status as sub-humans. This representation he continues was aimed at manufacturing the ‘Other’ for purposes of domination; it was an organised form of writing quite consistent with itself having very little to do with the actual people been represented. Orientalism was an unrealistic representation that is construed realism manufactured to create the ideal ‘Other’ for Europe and this facilitated their intrusion of ‘Other’ civilizations (Said 1978). The concept of Orientalism in Said’s theory, thus, becomes a way of seeing that imagines, emphasizes, exaggerates and distorts differences. This is the philosophical mindset with which the imperial West approached Africa, Nigeria to be specific. Imperial Britain using the expedition reports of Napoleon and especially Captain Clapperton of 1825 manufactured Africa as a set of degenerate heathens, savages and naïve primitives – this was a new hyper-real stereotypical vision of the colonized to facilitate and rationalise imperial domination. Listening to modern Church evangelicalism and watching media shows, as well as Nollywood drama in contemporary Nigeria, reveals a problematic representation of the arts that is consistent with itself which is akin to Western orientalist fantasies that manifested in the negative and derogatory representation of ‘Other’ cultures in the Nineteenth Century. There is a projection of negativity towards the visual arts based on stereotypes created by the colonialist and missionaries from the 1850s in West Africa. This paper focuses on analysing the problem of such orientalist fantasies and the continuous propagation of negative stereotypes about the arts in contemporary Nigeria and how such representations not only impede art appreciation but equally stifles patronage and artistic expressionism. It will first deconstruct the clandestine ways stereotypes are been propagated in Nollywood and modern Churches then describe the many ways it affects contemporary art since no essay or commentary till date has been tailored to address this new ideological attack on art through psychologically deception and colonization. But first, a bit of historiography will suffice at this point to establish the origin of art stereotypes and attacks in Nigeria and the political inclinations behind. II. Review of Literatures 2.1 Content Analysis Content analysis is a research tool that determines the presence of certain words, themes, or concepts within a given qualitative data. It enables researchers to analyse data to establish the meanings and relationships of such words, themes, or concepts in articulating a particular viewpoint. Two main features of content analysis are central to its adaptation in this study – Krippendorff (1980) opines that it constitutes a technique for making inferences by systematically and objectively identifying special characteristics of messages; while for Berelson (1952) content analysis is envisaged as a research technique for the objective and quantitative description of the manifest content of communication. These theories point to the fact that content analysis helps to identify the intentions, focus or communication trends of an individual, group or institution, and it reveals patterns in communication content. Applied herein, this analytical tool is used to determine the content of themes and concepts in Nollywood movies and church sermons to unearth a consistent trend of negative dramatization using art forms that contributes to promoting disdain for the visual arts. It is used to deconstruct the many ways in which art is represented in Nigerian mass media and how that affects art perception, appreciation and patronage. 2.2 Colonialism and the Origin of Art Stereotype/Attacks in Nigeria Colonisation is not satisfied merely with holding a people in its grip and emptying the native’s brain of all form and content. But by a kind of perverted logic, it turns to the past of oppressed people, and distorts, disfigures and destroys it (Fanon 1961, pp.199). The process of colonisation often involved warfare, deformation of existing traditional structures and interference with the cultural existence of the colonised (Ayande 1966). This was the case in West Africa as the British government to a great extent, deformed or erased African customs and cultural values which they branded ‘primitive’, to impose Western supposedly ‘superior’ civilisation. This deformation and erasure of established traditional structures adversely altered the African continent. Missionaries sent to Africa from the 1840s paved the way for this cultural dismantling of African traditions. Coached in Western imperialist ideologies, missionary propaganda in West Africa was politically inclined (Venn 1865, pp.10). While they arrived Africa with codified message of ‘salvation’ and the gift of ‘civilization’, they had their minds firmly fixed on the material resources of the continent (Galloway 1960), because missions were part of Western symbols of power, and “Christianity was integrally saturated as part of a larger order, comprising Western education, colonial administration, commerce and industry, with which everyone had henceforth to reckon” (Horton 1971, pp.91). With this juxtaposition of Church mission and colonialism, missionary enterprises set out to achieve a new social order in Africa using radical evangelicalism. Propelled by the idealism of a faith which they believed was instrumental to enlightenment, social progress and technological advancement, compromising with primitive values was inconceivable. Their first step was to erase all aspects of the colonised customs/cultural idiosyncrasies, perceived as stumbling blocks. This presupposition led to traditional African religion and art coming under extreme Western attacks because in pre-colonial Africa, Africans way of life was defined by traditional religious belief systems and cosmologies, thus, tenaciously adhered to the laws of the land and the ordinances of gods and ancestral spirits as templates for their existence. This reliance on traditional belief systems and ideologies provided Africans spiritual indemnity, which missionaries and colonizers soon realized was a major hindrance to evangelicalism and a threat to the establishment of colonial rule (Goldie 1890). As Henry Carr observes, “it is to be remembered that at the initial stage work, the first duty is to create new social order; the first battle is with superstition and the old other of things” (Carr in Galloway 1900, pp.29). To overcome these perceived hindrances, missionaries adopted a negative approach of viciously attacking African religion and its paraphernalia by branding them evil, barbaric, ritualistic, idolatry and superstitions (Bascom 1953, pp.495). This outright condemnation by resorting to stereotyping of African religion and customs was the greatest tool adopted by missionaries in their quest to reconstruct African social order and plough the way for colonial rule. This is because, by creating derogatory representations of the colonized culture and customs, the imperialist formulated a construed moral justification, a rationale to underpin the erasure of existing traditional structures in order to facilitate imperial conquest and domination. This theory is put forward on the basis that the formulation of stereotypes by the West was a strategy aimed at gaining power over the stereotyped since as Sander Gilman points out, “stereotyping was a political rhetoric to gain and exercise control over the stereotyped,”(Gilman 1985, pp.21) also, because “power encourages stereotyping while stereotyping helps to maintain power” (Fiske 1993, pp.621). Projecting negative imagery unto the ‘Other’ became a form of power, of control and domination associated with colonialism. The condemnation and stereotyping of African religion and art as barbaric, superstitious and evil, was rooted in this imperial philosophy of domination which Africans could not decipher immediately. Art was the fulcrum of traditional African religion and the focal point for supreme deities, resident ancestral spirits and revered natural phenomena, since “traditional African art evoked and abstracted the powers central to human life” (Hackett 1994, pp.294). It abstracted African beliefs, religion and cosmology as a result of which, it became the major object of attack by the West. Sermons were used by missions to debunk and dispel traditional ideologies/beliefs from the minds of converts, and from 1847 that Church missions established and monopolised schools in West Africa, mission schools were used as podiums for vicious attacks on African art (Ogiube 2002). From 1906 when the British government took over control of schools in Nigeria, following the blueprint set by missionaries, they omitted art from colonial schools and used military force to eradicate all forms of traditional art, as adduced by the Benin Expedition of 1897, the Ijebu Expedition of 1908 etc. Besides, the colonizers developed the racist stereotype that Africans lacked intellectual and creative capabilities to create art, to ensure that art wasn’t practised in any form in colonies under Britain and those who attempted to create art were sternly rebuked (Oguibe 2002, pp.245). Problematically, through the adoption of the strategy of stereotyping by the West, Imperialist projected onto Africa, its arts and religion negative imagery of primitivism/barbarism, and inferiority as sub-humans. Church missionary enterprises which instigated these stereotypes did so on the paradoxical premise that African religion and its paraphernalia, prevented the colonized from attaining civilization, or gaining salvation and social progress. However, a deconstruction of colonial intent using postcolonial analytical tools and Edward Said’s Orientalism proves otherwise. The stereotyping and condemnation of African art and culture was politically driven to achieve the following: a) to exterminate traditional African religion and stripe traditional African arts of its powers thereby disorientating the natives for imperial subjugation, b) Stripe traditional African rulers of their powers and the visual symbols upon which their divine authorities where inscribed, and c) ensure the erasure of traditional African heritage, structures and reference to their very existence. But the major problematic created by church missions and imperialist condemnation and stereotyping of African traditional art and religion was the creation of a new culture of disdain for the arts and traditional values by psychological imprinting negative stereotypes about art in the minds of Nigerians using the weapons of evangelism, church podium and military might. That culture of art attack created by the colonialist has persisted and continues into this contemporary era with far more damaging consequences. Nollywood and Nigerian churches still propagate the same colonial rhetoric and negativity towards the arts and are responsible for poor reception, appreciation and patronage of visual arts in contemporary Nigeria. III. Discussion 3.1 Orientalist Fantasies in Nollywood and the Mis-representation of the Arts a. The Dramatization of Art Objects as a Mechanism for Evil Nollywood seems to be consistent in its attack on art by continuing the propagation of the stereotypes about art created by the imperialist as a vehicle for heathenism. Although postcolonial studies have largely debunked such representation as misconstrued and politically motivated, Nollywood continues to do otherwise by propagating negative imagery that poses the biggest challenge to artistic expressionism and appreciation in contemporary Nigeria. Many home movies are consistent in their expression of two forms of narratives – on the one hand, the narrative of the prevailing of good over evil and on the other, the canonization of westernization as the ideal form of civilization, thus, projecting the ideology that identifying with cultural norms amounts to associating with primitivism and evil. These narratives are construction of hyperrealism to foster the supposed assumption of high spiritual status in the religion of the West by the writers of such scripts. To dramatize the prevailing of good over evil, Nollywood writers draw upon physical forms as a representation of the transcendence or metaphysical realm and forces of African evil which must be destroyed. Storylines are constructed that portray the presence of evil forces in society through their physical occupation of relics or other art objects. Evil is often dramatized to extrude from a physical form to which it returns to reside after perpetuating its act. The problematic lies in the fact that following the narratives created by the missionaries in the 1850s, sculptural forms or three-dimensional art objects are mostly used in these representations. In doing so, Nollywood dramatizes art objects and artefacts as a mechanism for evil, making it appear as though art is synonymous with dark practices. This ideology is best captured when dramatizing the prevalence good to prevail over evil in Nigerian home movies. Scenes are created in which artefacts are burnt or destroyed by pastors who represent good forces, and the scenes that follow next portray the liberated society or person in a better place. In summary what they peddle in their construed fantasies in such storylines is that when art objects and artefacts are destroyed, evil disappears and good prevails then the society is transmuted from primitivism to modernity and from barbarism to civility. b. Association of Traditionalism with Backwardness Nollywood also constructs a representation that associates traditionalism with primitivism and backwardness. Writers of home movies create a binary of difference that separate those considered civilized in cities and the primitives in villages or the countryside. City life is canonised as modern by invoking Western cultural assimilation and identification with Christianity. On the other hand, village life is constructed by reference to traditional cosmologies, customs, food, festivities etc. This narrative constitutes seventy per cent of all Nigerian movies, thus, formulating and propagating a problematic ideology that those who identify with traditional customs automatically become primitive, evil and backward. This celebration and canonization of westernization as the compass for civility and contemporaneity is similar to the cultural imperialism imposed on Nigerians and Africa during colonialism. In contemporary society, such a narrative is adversely dangerous because it threatens to completely erase African cultural identity and uniqueness. This is because Nollywood representation creates a difference by constructing orientalist visions of communities/villages and traditional customs that are far from the real or truth and inconsistent with the lifestyle and values of people who live there. This is consciously done by the scriptwriters to sell a sense of contemporaneity constructed around modern cities and the assimilation of western lifestyle, dressing, food, culture etc., as the model for civilization, thus, influencing consumers of such movies to turn away from traditional customs and material culture which the frame as the complete opposite of civility and modernity. In framing such anti-art scripts in Nollywood and their subsequent broadcasting through the media, it inadvertently propagates widespread disdain for the arts which in turn impede both artistic expressionism, perception and appreciation. This theory is based on the fact that the fantasies of art constructed in Nollywood are problematic/dangerous dissemination of fallacious colonial ideologies. The dramatization of art as a mechanism for evil perpetuation alienates the Nigerian artworld by constructing and inscribing negative imageries, stereotypes and fantasies about the arts in the minds of the citizenry who now continue to look at art through the negative compass dramatized Nollywood movies. The resultant effect is the poor patronage, appreciation and the overt disdain for the art visible in our contemporary society. Galleries are often empty during private views and unlike the West, you can never see families taking day trips to galleries and museums in Nigeria to assimilate artworks on display as part of their holidays or weekend outing. Nollywood has a close companion in its anti-art propaganda and that is Nigerian churches. Christianity in Africa was developed by the missionaries on anti-art, anti-culture and anti-customs foundations and modern churches are keeping that stereotypical torch alight and unwittingly contributing immensely to damaging art reception and development in contemporary Nigeria. 3.2 Anti-Art Propagandism in Modern Nigerian Churches In many ways, the main obstacle to appreciation and reception of art in contemporary Nigeria is the Church. Modern churches framed in colonial ideologies and Eurocentrism continue to propagate white supposed supreme religion, thus, engage in the condemnation of art especially visual arts by associating it with evil. Inspired by the construed missionary narratives contemporary churches also problematically associate the manifestation of any form of evil with the presence of artefacts. In essence for many in the religious spheres in Nigeria, art forms constitute focal points for resident evil hence are the medium by which evil reside in society. Using such misconstrued lens to look at art, churches have created a borderline between the church and the arts. In the views of many in the Christian realm, it is inconceivable to practice certain aspects of art and still be religious or spiritual. This is reminiscence albeit in a negative sense of the same narrative developed by missionaries in the 1850s, but which now forms a major feature of Christianism in Nigeria. The Church continues to advance a new culture of art attack turning the arts into the major punching bag by some men of GOD to display their supposed spiritual prowess. They demonstrate this through the destruction of art objects as the physical manifestation of the supposed spiritual overcoming of dark forces. During deliverance exercises, these religious men and women engage in such display to promote what Michel Foucault described as Pastor Power (Foucault 1979), a mechanism of psychological wheedling to colonise members for their churches. Although fully aware that spiritually evil is surpassed through prayers without resorting destruction of material culture, these religious still engage in the condemnation and destruction of artefacts knowingly or otherwise to extend missionaries stereotypes and cowing religious followers into believing their divine mandate. Churches create narratives that associate every challenge with a metaphysical interference hence propagate the need for deliverance to free members. Although the concept of deliverance is laudable, the major problematic lies in the fact that to make such narratives believable, religious men and women interpret metaphysical realities as resident in the physical world through the presence of artefacts especially sculptural relics. And very often deliverance is said to be complete and effective done only when certain artefacts in believer’s homes are destroyed by burning. What this has done for decades now is continue to add to the culture of art attack through the projection of negative stereotypes that associate art with evil hence hindering art appreciation and enjoyment. This is because churches have succeeded through such negativity towards the arts in instilling fear in the minds of followers that owning artworks almost tantamount to associating with evil. The sight of art forms especially sculptures in contemporary Nigeria stir sentiments of disdain amongst many Nigerians since the nation is highly religious. Some parents even forbid their children from studying art by threatening to disown them, which goes a long way to demonstrate the implications of churches attack on the arts. This religious attacks on the arts grossly affects artists who struggles to get clients or patronage for his or her art. 3.3 The Impact of Nollywood and Churches Stereotypes on Contemporary Art a. Poor Reception, Patronage and Appreciation The combine onslaughts of Nollywood and contemporary churches’ orientalist fantasies of art has contributed in impeding the development of art in contemporary Nigeria in many ways. The problematic propagation of negative stereotypes about art has resulted in poor reception, patronage and appreciation of art amongst the citizenry. Nigerians show very little regards for arts since it has been drummed into the core of their consciousness through Nollywood and churches that association with art will draw the negativity of traditionalism and primitivism. As a result, some who have designated themselves Christians though exposed educationally, distance themselves from certain art forms such as sculptures. According to Yemisi Shyllon churches and the negative stereotypes about art they project through “overbearing religiousness presupposes orthodoxy, is the greatest enemy of art as religion is being used to destroy the psyche of Nigerians to art” (Shyllon 2013, pp.97). This is particularly true because Nollywood and modern churches continue to create the impression that in contemporary the context, appreciating art and having artefacts adorn ones homes, automatically amounts to paganism. This negativity towards art developed through stereotype filters into government, so that from the government angle art is equally attacked and degraded. This is more so because many who occupy public offices are equally cowed through misconstrued church sermons. As Mamza observes, One of the problems affecting art teaching and learning in Nigeria, is the ambivalent negative attitude of Nigerian society and the government towards the subject and lack of recognition of art by government, as well as societal misconception that artists have inferior personality constitute more problems (Mamza 2007, pp3). Government policies on art are at best fire brigade approach or cosmetic policies when it comes to matters of art development and inclusion in national planning. Government or institutional negativism towards art occasioned by misconstrued stereotypes about art has directly led to problems of art development in Nigeria derived from the ineptitude in the administration of art and indirectly from the ephemeral interest of government. To adduce institutional disdain for art one need not look further beyond the overarching governmental emphasis on science and technology and complete relegation of art to the background (Kashim & Adelabu 2010). The major problem with this inscription of negative stereotypes about art in the minds of Nigerians through Nollywood and contemporary churches, is the drastic reduction in art patronage. Besides turning people away from art by influencing their appreciation of the field, Nollywood and churches contribute to discouraging patronage of art in Nigeria. Outside graphic art forms used as souvenirs during social functions and political events, many Nigerians shy away from patronising artworks with subversive, abstract or controversial content or formalism. The very few who patronise art are mainly those with global orientation who see beyond the orientalist fantasies peddled in Nigeria media and churches about art expressionism. The remaining 95% of Nigerians are psychologically colonised by the misconstrued condemnation of African cultural values and material culture as primitive or barbaric, as result distance themselves from artefacts. b. Discouraging Artistic Expressionism The culture of art attack in Nigeria for which Nollywood and Churches are culpable, problematically discourages artistic expressionism and creativity in contemporary Nigeria. Firstly, the stereotypical representation of art causes disdain for the field and very often misguided relegation of artist to the background of society. This has overbearing impact on the contemporary Nigerian artworld in two perspectives – firstly is dampens the creative spirit of professional artists who because of low patronage and the attacks on arts shy away from engaging in the creation of highly expressive, subversive or philosophical magnum opuses which often not unpatronised. Artists in this condition are forced into penury with many abandoning the field completely for other respected and lucrative careers like banking, pastoring, politics etc., to be economically able to sustain their families. Secondly the culture of art attack leads to lack of creative engagement to the highest level in Nigeria. This is because knowing full well that only graphic communications such as poster designs, banners, souvenir branding etc., flourish and are acceptable in Nigeria, many artists abandon the creative fields of painting, sculpture, ceramics, animation etc., to pitch their tent in the functional fields of graphic communication, printmaking and fashion design. In this sense, creative thinking that combines the imagination of an artists with his technical dexterity to codify forms with content that address various notions of power to bring about societal transformation are abandoned. Thus, the arts suffer greatly because gradually artist have lost their subjective powers of expression occasioned by constant art attack and misrepresentation in the media. As Osear Wilde opines, The moment an artist take notice of what other people want, and tries to supply their demand, he ceases to be an artist, and becomes an amusing craftsman…an honest or a dishonest tradesman, since art is the most intense mode of individualism that the world has known (Wilde 1891, pp.40). Art in Nigeria has unfortunately been reduced to amusing functional crafts as a result of artists been forced to abandon their creative subjectivity and imaginative individualism, to rather embrace the economically profiting genres of graphic communication and printmaking patronised many Nigerians. IV. Conclusion For contemporary Nigerian art to grow and become widely accepted, a re-orientation is needed to change the negativity surrounding the field informed by continues misconstrued representations propagated in Nollywood and Nigerian churches. What this research has done is to create a link between the current poor patronage and disdain for the arts with activities within Nollywood and Churches. The paper asserts that continues association of art with heathenism and primitivism is directly responsible for the decline in art appreciation, patronage and most problematically the decline in subjective creative expressionism in the arts. The Nigerian artworld as pointed out is a victim of the combine onslaught of the Nigerian media, home theatre and churches, thus, stifling its development and growth and impeding the development of individual artist many of whom have since abandon the arts as a result of poor patronage. For art to excel, government must stop the relegation of the arts to the background and begin funding the arts in the same magnitude science and technology are funded. Made in Nigeria art and products should be patronised and art/design should be repositioned for national development as is obtainable in other advanced countries. It is also contended in this paper that those who attempt to authenticate their script writing prowess by condemning the arts through derogatory dramatization should attuned themselves with the current ideology of postcolonial cultural promotion as a variant of asserting a distinct African modernity and pride. Finally, modern Nigerian churches should begin to view art through renaissance compass where the visual arts contributed immensely to the visualisation of religious ideologies to promote worship. Until this is done, contemporary art will not be fully embraced in Nigeria and harnessed for national modern development. References
Spatial distribution and activity patterns as welfare indicators in response to water quality changes in European sea bass, Dicentrarchus labrax Sébastien Alfonso, Bastien Sadoul, Xavier Cousin, Marie-Laure Bégout To cite this version: HAL Id: hal-03135465 https://hal.inrae.fr/hal-03135465 Submitted on 22 Aug 2022 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution - NonCommercial| 4.0 International License Spatial distribution and activity patterns as welfare indicators in response to water quality changes in European sea bass, *Dicentrarchus labrax* Sébastien Alfonso\(^1\), Bastien Sadoul\(^2\),\(^3\), Xavier Cousin\(^2\),\(^4\) and Marie-Laure Bégout\(^1\),\(^2\) 1 Ifremer, Laboratoire Ressources Halieutiques, Station de La Rochelle, Place Gaby Coll, 17137 L’Houmeau, France. 2 MARBEC, Univ. Montpellier, CNRS, IRD, Ifremer, 34250 Palavas-les-flots, France. 3 INRAE, UR1037 Fish physiology and Genomics, 35000 Rennes, France 4 Université Paris-Saclay, AgroParisTech, INRAE, GABI, 78350 Jouy-en-Josas, France. * Corresponding author: Sébastien Alfonso Phone: +39 (0) 809 246 190; e-mail: Sebastien.alfonso1@gmail.com Present address: COISPA Tecnologia & Ricerca, Via dei trulli 18, 70126 Torre a Mare (Bari), Italy. Abstract In aquaculture, fish are exposed to unavoidable stressors that can be detrimental for their health and welfare. However, welfare in farmed fish can be difficult to assess, and, so far, no standardized test has been universally accepted as a welfare indicator. This work contributes to the establishment of behavioural welfare indicators in a marine teleost in response to different water quality acute stressors. Groups of ten fish were exposed to high Total Ammonia Nitrogen concentration (High TAN, 18 mg.L\(^{-1}\)), Hyperoxia (200 % O\(_2\) saturation), Hypoxia (20 % O\(_2\) saturation), or control water quality (100% O\(_2\) saturation and TAN < 2.5 mg.L\(^{-1}\)) over 1 hour. Fish were then transferred in a novel environment for a group behaviour test under the same water quality conditions over 2 hours. Videos were recorded to assess thigmotaxis, activity and group cohesion. After this challenge, plasma cortisol concentration was measured in a subsample, while individual behavioural response was measured in the other fish using novel tank diving test. Prior to this study, the novel tank diving test was validated as a behavioural challenge indicative of anxiety state, by using nicotine as anxiolytic drug. Overall, all stress conditions induced a decrease in activity, thigmotaxis and group cohesion while only fish exposed to Hypoxia and High TAN conditions displayed elevated plasma cortisol concentrations. In post-stress condition, activity was still affected but normal behaviour was recovered within the 25 minutes of the test duration. Our work suggests that the activity, thigmotaxis and group cohesion are good behavioural indicators of exposure to degraded water quality, and could be used as standardized measures to assess fish welfare. Keywords: Fish; Welfare; Water quality; Behaviour; Stress. 1. Introduction Fish production has expanded importantly during the last decades, both because of the world’s diminishing natural wild resources and the increase in demand for fish products (FAO, 2018). Aquaculture represented 53% of the total fish production (including non-food uses) in 2016 (FAO, 2018) and is now recognized as a major food production industry. Thus, as well as for terrestrial farming industry, concerns about sustainability, environmental issues and animal welfare in aquaculture are increasing (Conte, 2004; Ashley, 2007; Martins et al., 2010; Martins et al., 2012; Hixson, 2014; FAO, 2018; Lembo et al., 2019). It is common that under aquaculture conditions, and in every fish husbandry system, variations of water quality variables such as temperature, pH, oxygen ($O_2$), carbon dioxide ($CO_2$) or Total Ammonia Nitrogen concentrations (TAN) occur. Such variations when they reach a certain threshold, depending on the species preferendum, could be considered as stress factors (stressor) and therefore deleterious for fish health and welfare. The exposure to stressors, such as degraded water quality may mobilize fish energy for coping with the stressor hereby decreasing the available energy allocated to growth and reproduction, or directly causes death if the magnitude of stress is too high (Barton, 2002; Sneddon et al., 2016). Therefore, it can finally affect fish production and has economic consequences for farmers (Conte, 2004; Lembo et al., 2019). Exposure to stress factors triggers a cascade of biological events within an organism to cope with these factors. In fish, the hypothalamo-pituitary-interrenal axis (HPI) is involved in the production and release of cortisol into circulation acting as an activator of the physiological and behavioural responses (Sumpter, 1997; Sadoul and Vijayan, 2016; Schreck and Tort, 2016). Among the previously cited variables, oxygen and ammonia concentrations are known to activate the HPI axis when they vary, leading to the stimulation of cortisol release and the triggering of behavioural adaptive responses (Knoph and Olsen, 1994; van Raaij et al., 1996; Espmark and Baeverfjord, 2009). Thus, behavioural measurements have proven to be sensitive indicators of the complex existing biochemical and physiological changes that occur in response to stress (Schreck, 1990; Scherer, 1992; Schreck et al., 1997; Martins et al., 2012). Behaviours, such as changes in food-anticipatory activity, feed intake, ventilation rate, individual and group swimming activity are commonly used as welfare indicators (Huntingford et al., 2006; Martins et al., 2012; Huntingford and Kadri, 2014; Carbonara et al., 2015; Carbonara et al., 2019). Group swimming behaviour is defined as the spatial distribution and swimming activity of the group of fish held within an aquaculture production unit and it covers shoal structure, the horizontal and vertical distribution of the group, their swimming speed and direction (Martins et al., 2012). For instance, exposure to negative stimuli, such as poor water quality, is known to lead to rapid escape movements (Stien et al., 2007; Bratland et al., 2010) or to alter group cohesion (Domenici et al., 2002; Espmark and Baeverfjord, 2009; Sadoul et al., 2014; Sadoul et al., 2017). Thus, group swimming behaviour appears to be a sensitive welfare indicator even if it is still lacking calibration efforts to be precisely translated into an operational welfare indicator; nevertheless some examples exist (Papandroulakis et al., 2014; Pettersen et al., 2014). Moreover, the appraisal of negative or positive stimuli and, hence, the psychological dimension of stress as defined for fish by Galhardo and Oliveira (2009) is seldom tackled in welfare research. There exists however a complementary measure which is the individual behavioural responses to novel environment and in particular the novel tank diving test which is worldwide used along with the measure of stereotypies, such as thigmotaxis to assess anxiety in zebrafish (Danio rerio) in ecotoxicology and pharmacology research (Levin et al., 2007; Egan et al., 2009; Vignet et al., 2014; Macaulay et al., 2015; Alfonso et al., 2019a). In further details, the novel tank diving test was validated as a tool for evaluating anxiety by using drugs, such as nicotine. Short exposure to nicotine is known to reduce anxiety in fish, through its action on nicotinic acetylcholine receptors as demonstrated by the use of specific inhibitors (Levin et al., 2007; Bencan & Levin, 2008). In the context of novel tank diving test, nicotine-exposure (bathing) has been shown to be anxiolytic by triggering change in fish space utilization, such as higher time spent in the top area of the novel tank which translate a relief from bottom dwelling behaviour that fish would express under predator threat for example. The novel tank diving test could thus be a helpful non-invasive tool to monitor farmed fish anxiety state post stress exposure hereby assessing psychological stress and contributing to the assessment of positive or negative emotions and, hence better welfare state determination. Overall, the objectives of the present study were to further contribute to the establishment of behavioural welfare indicators including the psychological dimension of stress in a model marine teleost in response to different water quality stressors. Firstly, the novel tank diving test outcome was validated as a behavioural indicator of anxiety in European sea bass *Dicentrarchus labrax*, using nicotine as an anxiolytic reference drug. Secondly, behavioural responses of fish group in response to a novel environment under acute and severe water quality deterioration, including Total Ammonia Nitrogen (High TAN) increase (18 mg.L\(^{-1}\)), Hyperoxia (200 % O\(_2\) saturation) and Hypoxia (20 % O\(_2\) saturation) were evaluated along with cortisol measurement. Finally, individual behaviour expressed following the same water quality exposures were assessed using the novel tank diving test translated from ecotoxicology studies. 2. Material and methods Experiments were authorized by ethics committee agreement APAFIS#7098 and all procedures involving animals were in accordance with the ethical standards of the institution and followed the recommendations of Directive 2010/63/EU. 2.1. Fish rearing Juvenile European sea bass were hatched and reared at Ifremer Palavas-les-flots research station (France, 34250) until 280 days post fertilization (dpf) according to sea bass rearing standard (Chatain, 1994). They were then transferred to Ifremer L'Houmeau (France, 17137). No mortality occurred during the transfer between the two facilities. They were then randomly separated in groups of 100 fish into 4 tanks of 400 L (90x90x50 cm). Tanks shared a recirculating system with a flow rate of 4 m\(^3\) per hour and water was renewed at a rate of 20 % per day. Water temperature was maintained at 21.5 ± 1°C, oxygen around 100 % saturation, and salinity and pH were respectively set to 20.5 ± 1 and 8.3. The light regime was 13:11 L/D. Total Ammonia Nitrogen (TAN) concentration was < 2.5 mg.L\(^{-1}\) (equivalent to 0.1 mg.L\(^{-1}\) [NH\(_3\)]). The fish were hand-fed using commercial diet from Le Gouessant (France) once a day each morning at 9:00 at 1 % of biomass. Fish were reared in L'Houmeau for 3 months before the first experiment. 2.2. Translating and validating the novel tank diving test in European sea bass The novel tank diving test assessing position choice along the vertical dimension has been previously validated as a metric of adaptation to a novel environment and a proxy of the anxiety level of individual fish (Levin et al., 2007; Egan et al., 2009). The first objective of this work was to adapt the test protocol (observation duration, tank size relative to fish size) to European sea bass, and then to validate the measure of anxiety using nicotine as a reference anxiolytic drug. Two groups of fish (385 dpf, n=24 per group) were randomly selected and transferred from the home rearing tank to two 50 L tanks into the experimental room. After a 1-hour acclimation period, control fish (n=24) were transferred one by one in a 3L tank with the same water quality for 8 min (24.5 x 15 x 13.5 cm, AquaBox 3; Aqua Schwarz GmbH). The same protocol was followed for the nicotine-bathed fish (n=24), except they were bathed one at a time during five min in a 3L tank containing 5 mg.L⁻¹ nicotine solution (Pestanal®, Sigma Aldrich) then placed in normal plain water for the next three minutes. After a 1-hour acclimation period, control fish (n=24) were transferred one by one in a 3L tank (24.5 x 15 x 13.5 cm, AquaBox 3; Aqua Schwarz GmbH) filled with normal plain water for five min and then transferred to a second 3L tank (same water quality) for an extra three min. The same protocol was followed for the nicotine-bathed fish (n=24), except they were first bathed one at a time during 5 min in a 3L tank containing 5 mg.L⁻¹ nicotine solution (Pestanal®, Sigma Aldrich) added to normal water and then transferred in plain water for the next three minutes. This two steps bathing protocol was applied to ensure correct elimination of nicotine (at least in the gills) and to ensure similar handling for both conditions. For both treatment, directly after the bathing period, the individual fish was gently transferred in a novel tank containing normal plain water (29 x 21 x 17 cm, 10 L trapezoid tank from Aquatic Habitat. Inc.), and a video was recorded in side view during 25 minutes. For space occupancy analysis, the tank was virtually separated into two areas according to Egan et al. (2009): top area including one half of the volume and bottom area including the other half. Time spent in top area (s) and latency to enter top area (s), variables which are both indicative of anxiety level, were measured. In addition, distance travelled (cm) and number of transitions between areas, indicative of fish activity level were also measured. Variables were recorded in each frame and they were summed over periods of 5 min or over the whole test duration (i.e. 25 min). 2.3. Exposure to stress condition and water quality characterization In the morning prior to the experiment (i.e. exposure to stress condition), a group of 10 fish was gently randomly caught from the rearing tank and transferred to the behavioural room where they were maintained in a tank (70 L, height 48 cm, diameter 49.5 cm) filled with 60 L of the same water as in their home tank (Figure 1). Fish were kept under standard condition during 1 h for tank acclimation and then, during the next hour, one of the four following conditions was applied i.e. Control, High Total Ammonia Nitrogen (TAN) concentration, Hyperoxia and Hypoxia. Experiments were performed in triplicates (n=10 fish x 3 run per condition). For the control condition, fish were maintained under the same standard condition than in the rearing room (i.e., at 21.5 ± 1°C, 100 % O₂ saturation and TAN < 2.5 mg.L⁻¹). For high TAN condition, 8.5 g of ammonium chloride NH₄Cl (Fluka 09711, Sigma Aldrich) dissolved in 0.5 L of water was added twice at 30 min interval to reach a targeted TAN concentration of 18 mg.L⁻¹ which corresponds to 1.6 mg.L⁻¹ of NH₃. Three water samples (50 mL) were taken to quantify a posteriori the TAN concentration: (i) before adding ammonium chloride, (ii) at the beginning and (iii) at the end of the novel environment in group. Samples were stored at -22°C before further analysis. Then, TAN concentration was quantified using a spectrophotometer with continuous flow (Alliance Integral Futura, Frépillon, France) and analytical method is described below. Samples were filtered using GF/F 0.7μm filter (Whatman, Maidstone, United Kingdom). TAN concentration was quantified using a spectrophotometer with continuous flow (Alliance Integral Futura, Frépillon, France) using colorimetric method. The solutions used for the calibration analyses that were performed the same day came from stock solutions from 0.1g.L⁻¹ to 1g.L⁻¹ of ammoniacal nitrogen (NH₄⁺) stocked at a temperature of 8°C. The calibration curve of ammoniacal nitrogen showed a high R² validating the procedure (NH₄⁺=1.439 x OD - 0.002; R² = 0.99, where OD is the optical density measured using the spectrophotometer). The NH$_3$ concentration was determined using the following equation as described by Johansson and Wedborg (1980): $$[NH3] = \frac{[NH_4^+]}{K_1 \times [H^+]}$$ Where $[H^+] = 10^{-pH}$ and $log K_1 = -0.467 + 0.00113 \times $ salinity $ \times 2887.9/temperature$ (K) according to Johansson and Wedborg (1980). For Hypoxia condition, oxygen concentration was slowly lowered to reach 20 % of O$_2$ saturation using nitrogen bubbling. For Hyperoxia condition, oxygen concentration was slowly increased to reach 200 % of O$_2$ saturation using oxygen bubbling. Oxygen concentration was monitored every 5 min during the entire experiment using an Oxygen probe (Oxi 3310, WTW, Xylem Analytics Germany Sales GmbH & Co. KG). Oxygen concentration, NH$_4^+$ and NH$_3$ concentrations recorded over the experimental duration are presented below. For control condition, water oxygen concentration was maintained at 100% saturation (at 21.5 ± 1°C) and TAN concentration was < 2.5 mg.L$^{-1}$ during both bathing and novel environment in group. For High TAN condition, oxygen concentration was above 100 % and TAN concentrations were 15.3 ± 4.2 and 18.8 ± 7.6 mg.L$^{-1}$ at the beginning and at the end of the test respectively, corresponding to UIA-N concentrations of 1.34 ± 0.37 and 1.64 ± 0.67 mg.L$^{-1}$. For both Hyperoxia and Hypoxia conditions, TAN concentration was maintained at less than 2.5 mg.L$^{-1}$. For the hyperoxia condition, oxygen concentration increased slowly during the bathing period to reach 208 ± 5.6 % of saturation, while for the hypoxia it slowly decreased to reach 21.3 ± 3.8 % of saturation before the start of the novel environment challenge in group. All conditions were then maintained during two hours until the end of the group test (Figure 2). In the high TAN condition, the concentration of NH$_3$ represents half of the LC50 concentration reported for European sea bass after 96 h of exposure under similar hydrological conditions (i.e. temperature=17.5°C, salinity=34, and pH=8.15) than in our experiment (Person-Le Ruyet et al., 1995). After the initial bathing period, the fish group was challenged in a novel environment with the same water quality (see section 2.4.1). After 2 hours, fish from two replicates were then monitored individually into novel tank diving test in plain system water (see section 2.4.2, n=20 for control, n=20 for High TAN and n=18 for Hyperoxia and Hypoxia). The third replicate was used to quantify plasma cortisol concentration following the challenge in group (n=10 per condition, see section 2.5). Fish were randomly selected for blood sampling or for performing novel tank diving test. After blood sampling (n=9 or 10 fish per condition) or novel tank diving test, all fish were measured for weight (g, to the nearest mg) and standard length (cm, to the nearest mm) under the same anaesthesia conditions (see section 2.5). 2.4.Behavioural procedures All behavioural experiments were performed in a dedicated room where environmental parameters were identical to rearing conditions. All videos were recorded at 25 frame.s\(^{-1}\) with an analogue camera ICD-48E (Ikegami) and a 2.1-13.5 lens (Fujinon) linked to a computer with an acquisition card and EthoVision XT 10.0 software (Noldus, The Netherlands). Data extraction and analyses were performed using EthoVision XT 13.1 software. Swaps between individuals during novel environment in group were manually corrected using the track editor module (Noldus, The Netherlands). 2.4.1. Novel environment in group After the bathing period, the entire group of fish (n=10) was gently transferred into a novel arena (110 cm x 110 cm x 6 cm, 70 L). After 1 min, video recording started for 2 hours in top view. For each condition, water parameters were maintained similar to those obtained at the end of the bathing period for the respective condition following the same procedure explained in section 2.2.2. For space occupancy, the visualization of heat maps was produced for each 5-min period using Ethovis X 13 (Noldus The Netherlands). For further analysis, the arena was separated into two areas: Centre area including one half of the volume and periphery area including the other half; time spent in periphery (s), indicative of thigmotaxis behaviour (Ferrari et al., 2014), was recorded. Distance travelled by each fish (cm), indicative of individual fish activity, and the interindividual distances (cm), indicative of group cohesion (Buske and Gerlai, 2011), were also recorded. Variables were recorded for each frame and they were summed (for Distance travelled) or averaged (for time... spent in periphery and interindividual distances) over period of 5 min every 30 minutes (i.e., four sampling periods: 0-5 min, 30-35 min, 60-65 min and 90-95 min). 2.4.2. Novel tank diving test post-stress condition After novel environment challenge in group, fish were gently transferred individually into a novel tank (same as the one used for method validation with nicotine, see above) containing plain system water. Fish swimming activity and vertical position was monitored during 25 min to assess anxiety state and behavioural recovery following stressful conditions exposure. For space occupancy and fish swimming activity analyses, the same procedure as presented before in section 2.2 was followed. 2.5. Cortisol measurement Immediately after the end of the observation period in the novel environment challenge, fish were gently caught and transferred into a 10 L tank which contained 500 μL.L⁻¹ of a benzocaine stock solution (50 g.L⁻¹ in 100 % ethanol; Benzocaine Sigma-Aldrich, Saint-Quentin Fallavier, France). Blood samples were obtained within 3 minutes from the venous sinus with heparinised syringes. Thereafter, blood was centrifuged (5 min at 4000 g) to obtain plasma samples which were stored at -22°C until further analyses. Plasma cortisol concentration was determined by ELISA (RE52061, IBL International, Hamburg, Germany) using a Synergy-HT (BioTek Instruments, Winooski, VT, USA) following manufacturer instructions. At the end of the experiment, all fish were euthanized and sexed using an overdose of benzocaine (1 mL.L⁻¹ from the stock solution described above), following the recommendations of Directive 2010/63/EU. 2.6. Statistical analyses Statistical analyses were performed using Statistica 9.0 software (StatSoft, USA). All statistical analyses were carried out at a 5 % level of significance and values are represented as mean ± SEM except where otherwise mentioned. Normality and homoscedasticity were tested a priori using Shapiro-Wilks test and when sample sizes were too small non parametric statistics were used. Fish weight and length were compared between conditions using one-way ANOVA to ensure no bias existed for behavioural and physiological responses interpretation. For validation of the Novel tank diving test, time spent in top area and distance travelled were compared between fixed factors (Nicotine bathed vs. Control) with a repeated-measures ANOVA (with 5 periods, i.e. 5-min, 10-min, 15-min, 20-min and 25-min) and a Tukey HSD post-hoc test. A Mann-Whitney U-test was also performed to compare between conditions, total time spent in top area, latency to enter top area, total distance travelled by fish and number of transitions between top and bottom areas. For Novel environment challenge in group, distance travelled, interindividual distances and time spent in periphery area were compared between conditions with a Factorial ANOVA (with 4 periods, i.e. 0-5 min, 30-35 min, 60-65 min, 90-95 min) followed by Tukey HSD post-hoc test. For novel tank diving test post-stress condition, time spent in top area and distance travelled were compared between conditions with a repeated-measures ANOVA (with 5 periods, i.e. 5-min, 10-min, 15-min, 20-min and 25-min) and a Tukey HSD post-hoc test. A One-way ANOVA followed by Tukey HSD post-hoc test was performed to compare between conditions the total time spent in top area, latency to enter top area, total distance travelled by fish and number of transitions. Finally, since sex had no significant effect on plasma cortisol concentration, a Mann-Whitney U-test was performed to compare cortisol values between control and each condition. ### 3. Results Overall, 168 fish were used for the different experiments: 48 for the validation of the novel tank diving test (body weight: 50.8 ± 0.6 g, standard length: 15.4 ± 0.9 cm, n=24 per group); 120 for the stress condition exposures (51 ± 1 g, 15.3 ± 0.2 cm, n=30 per group), batches were homogeneous between conditions (F=1.5, df=3, p=0.23 and F=2, df=3, p=0.13 for body weight and standard length respectively). #### 3.1. Validation of novel tank diving test in European sea bass Irrespective of the condition (Nicotine bathed vs. Control) fish progressively explored the top area of the novel tank ($F=6.0, df=4, p<0.001$). Nicotine bathed-fish spent significantly more time in the top area than control ones during each 5-min period of the test ($F=31.8, df=1, p<0.001$; Figure 3.A) as well as over the total duration of the test ($Z=4.8, p<0.001$; Figure 3.B). Fish also progressively travelled more distance during the experiment whatever the condition ($F=13.3, df=4, p<0.001$) but nicotine bathed-fish travelled significantly more distance than control ones during each 5-min period of the test ($F=15.9, df=1, p<0.001$; Figure 3.C) as well as over the total duration of the test ($Z=3.5, p<0.001$; Figure 3.D). Nicotine bathed-fish swam more between the two areas and entered quicker in the top area than control ones ($Z=4.3, p<0.001$ and $Z=-5.0, p<0.001$ respectively; Figure 3.E,F). **3.2. Novel environment in group** Heatmaps, representing the mean location frequency of fish from different conditions and during different periods of the novel environment challenge in group, are plotted in Figure 4. For control condition, fish responded to the group test by staying mainly in the periphery of the arena during the first five minutes of the test. Progressively, they explored the centre of the arena. On the contrary, other groups of fish (*i.e.* High TAN, Hyperoxia and Hypoxia), were located in the centre area from the beginning of the test. In addition, fish dispersion increased over the test duration for exposed animals, while fish from the control condition stayed aggregated during the entire experiment. Under stress conditions, distance travelled by fish differed between conditions ($F=212.7, df=3, p<0.001$), and periods ($F=33.2, df=3, p<0.001$) with a significant interaction observed over time ($F=10.3, df=9, p<0.001$). Control fish travelled progressively more distance over the test duration; $3178 \pm 268 \text{ cm during period 0-5 min vs. } 5148 \pm 254 \text{ cm during period 90-95 min (p<0.001)}$. Fish from High TAN, Hyperoxia and Hypoxia conditions showed a lower distance travelled compared to control fish during the entire test ($p<0.05$ for all conditions) and it was stable over time (Figure 5.A). Interindividual distances, indicative of group cohesion, differed between conditions ($F=449.3, df=3, p<0.001$), periods ($F=17.4, df=3, p<0.001$) with a significant interaction between conditions and periods ($F=29.1, df=9, p<0.001$). Fish from control condition progressively decreased their interindividual distances during the challenge; 48.3 ± 1.4 cm during period 0-5 min vs. 41.9 ± 1.1 cm during period 90-95 min (p<0.001). During the 0-5 min period, fish from control and Hypoxia conditions showed similar interindividual distances (p=0.06), whereas fish from High TAN and Hyperoxia conditions swam closer to each other (p<0.001 for both conditions). However, starting from the 60-65 min to the 90-95 min period, fish from both High TAN and Hypoxia conditions showed higher dispersion than control fish (p<0.001) while fish from Hyperoxia condition continued to display lower dispersion than control fish from the beginning to the end of the testing period (p<0.001; Figure 5.B). Time spent in periphery area also differed between conditions (F=15.3 df=3, p<0.001), not between periods (F=0.5, df=3, p=0.66) but the interaction between conditions and periods was significant (F=10, df=9, p<0.001). Fish from control condition spent more time in the centre area from the second time period (30-35 min) until the end (90-95 min) compared to the first 0-5 min period (p=0.003, p=0.003 and p<0.001 for 30-35 min, 60-65 min and 90-95 min respectively). During the first 0-5 min period of the test, fish from High TAN, Hyperoxia and Hypoxia conditions spent less time in the peripheric area than control fish (p<0.001 for both conditions) whereas they spent the same time in the periphery during the rest of the test, with the exception of High TAN which still spent more time in Centre than Control during 30-35 period (Figure 5.C). 3.3. Novel tank diving test post-stress condition Irrespective of the condition, fish progressively explored the top area of the novel tank (F=5.9, df=4, p<0.001). There was an effect of condition (F=11.8, df=3, p<0.001) and an interaction between conditions and period were also found (F=4.4, df=12, p<0.001; Figure 6.A). The total time spent in top area differed according to conditions (F=11.8, df=3, p<0.001; Figure 6.B) with High TAN fish spending significantly more time in the top area than the three other conditions (p<0.001). Distance travelled by fish varied in relation to the duration of the test (F=13.0, df=4, p<0.001), conditions (F=15, df=3, p<0.001) and interactions between period and conditions were significant (F=3, df=12, p<0.001; Figure 6.C). Total distance travelled by fish also differed between conditions High TAN, Hyperoxia and Hypoxia fish travelled less distance than control fish during the novel tank test ($p<0.001$ for all conditions). No difference was observed for the number of transitions between the two areas between conditions ($F=2.3, df=3, p=0.8$; Figure 6.E) as well as for the latency to enter into the top area ($F=0.5, df=3, p=0.7$; Figure 6.F). ### 3.4. HPI axis response Plasma cortisol concentrations for fish from Hyperoxia condition were not different from control fish values ($Z=0.1, p=0.93$, Figure 7). On the contrary, plasma cortisol concentrations were higher for both High TAN and Hypoxia conditions compared to control values ($Z=-3.5, p<0.001$ and $Z=-2.1, p=0.04$ respectively). ### 4. Discussion Overall, this study demonstrates that commonly used behavioural tests in neurobiology or ecotoxicology on model species are relevant for evaluating anxiety in a model marine farmed fish and this opens new opportunities to evaluate psychological stress following environmental perturbation. Moreover, we have shown that activity, group cohesion and thigmotaxis are relevant behavioural indicators revealing acute exposures to High Total Ammonia Nitrogen (TAN), Hyperoxia and Hypoxia in a group situation. Individual bottom dwelling behaviour was also assessed in response to the same stressors using the novel tank diving test and proved to be sensitive. Fish display typical swimming features in a new environment, e.g. bottom dwelling, which have been used to define a suitable procedure to measure anxiety or anxiety-like responses. Common protocols exist for using these behavioural features for anxiety phenotyping in zebrafish (Levin et al., 2007) and they were successfully transferred to other small model species such as three-spine stickleback and fathead minnow (Margiotta-Casaluci et al., 2014; Thompson et al., 2016). To our knowledge, our study represents the first attempt to adapt this test for a larger fish of commercial and ecological importance such as European Sea bass (Vandeputte et al., 2019). Since this species is known to be a highly stress responding fish (Levin et al., 2007; Fanouraki et al., 2011; Alfonso et al., 2019b), we extended the test duration to 25 minutes. Despite this longer test period (usually between 5 and 10 minutes for other species) the time spent in the upper part of the tank remained limited to approximately 10%. Nicotine has been found to reduce anxiety in zebrafish through activation of acetylcholine nicotinic receptors (Levin et al., 2007; Bencan & Levin, 2008). In the context of novel tank diving test, nicotine-exposure has been shown to be anxiolytic by triggering change in fish space utilization. In the present study, acute treatment with nicotine induced the same relief of anxiety as observed in zebrafish (Levin 2007). It is to note however that the concentration we used, 5 mg.L$^{-1}$, was much lower than the one efficient in zebrafish (100 mg.L$^{-1}$) and a concentration of 50 mg.L$^{-1}$ was not able to induce change in bottom dwelling behaviour in zebrafish (Levin et al., 2007). Indeed, in zebrafish, exposure to nicotine results in a release from bottom dwelling behaviour (i.e. swimming in the top area of the novel tank) over test duration and increases the locomotor activity (Levin et al., 2007; Bencan and Levin, 2008). In the present study, after exposure to nicotine, sea bass similarly spent more time in the top area and were more active (i.e., travelled more distance and showed a higher transitions number between tank areas) compared to control. Altogether, these results advocate that anxiolytic effects of nicotine are behaviourally observable in European sea bass, as in zebrafish. These results firstly suggest conservation of the sensitivity to nicotine and the associated behavioural response in phylogenetically relatively distant fish species. This is supported by the high conservation of nicotinic acetylcholine receptors in fishes as recently shown (Pedersen et al., 2019) and the fact that we have found sequence coding for protein sharing high similarity with several nicotinic receptors in the genome of European sea bass (not shown). Secondly, this study supports the fact that the novel tank diving test is a promising tool for monitoring anxiety in marine teleost such as European sea bass. The four experimental conditions had very distinct water qualities. In the control condition, oxygen saturation was at 100% and TAN concentration was under 2.5 mg.L$^{-1}$ while TAN concentration was approximately 8 fold higher in High TAN condition and oxygen saturation was 2 fold higher and 5 fold lower in Hyperoxia and Hypoxia conditions respectively. TAN concentrations in the High TAN condition corresponded to a concentration of NH$_3$ of 1.6 mg.L$^{-1}$ (half of the LC50, Person-Le Ruyet et al., 1995). Oxygen saturations chosen during the Hyperoxia and Hypoxia conditions were previously described to affect fish physiology and behaviour during chronic exposure without being lethal (Chapman and Mckenzie, 2009; Espmark and Baeverfjord, 2009; Rimoldi et al., 2016). Both concentrations of oxygen and TAN used in the present study were quite extreme but can occasionally occur (or even co-occur) in aquaculture conditions in case of technical failures. In the novel environment in group, control fish displayed thigmotaxis behaviour and spent most of the time in the periphery area during the first 5 minutes of the test. Indeed, handling fish from bathing tank to a novel environment is known to induce a typical thigmotaxis behavioural response. This thigmotaxis behaviour has been shown to indicate an anxiety state (Prut and Belzung, 2003; Schnorr et al., 2012). Interestingly, fish from High TAN, Hyperoxia and Hypoxia conditions spent less time in the periphery area than control fish, which suggest that they were not displaying anxiety-like behaviour contrary to control fish in response to handling. High TAN, Hyperoxia and Hypoxia are known to directly affect fish survival (Magaud et al., 1997; Person-Le Ruyet and Boeuf, 1998; Shimp et al., 2005; Rimoldi et al., 2016). Indeed, fish survival can be impacted in many ways following their exposure to one of these stressors. For instance, in hypoxic conditions, the oxygen quantity is limited, therefore fish have to adapt their physiology and behaviour to maximize oxygen uptake and avoid death by asphyxia (Chapman & Mckenzie, 2009). Then, Hyperoxia may alter the equilibrium of ions in the gill, causes a decrease in the ventilatory frequency inducing oxidative damages or triggers diseases and thus can cause fish death (Dejours et al. 1977; Liepelt et al. 1995; Brauner et al. 2000). Finally, Ammonia exposure can affect osmoregulation, represses the immune system, or causes asphyxiation leading to hyperventilation, convulsions and death (Randall and Tsui, 2002; Eddy, 2005; Camargo and Alonso, 2006). By contrast to these stressors, handling is mostly documented for its effects on the HPI axis, through cortisol release (Barton 2002). To our knowledge, handling does not have direct effects on survival except if fish are injured which was not the case in our experiment. Therefore, we hypothesise that when fish are coping with stressors affecting survival, the thigmotaxis expression in response to a psychological stressor is overruled, possibly through endorphin release. Further mechanistic studies are needed to better understand what changes within the fish are related to these behavioural adaptations under multi-stressors exposure. Furthermore, during the test in group situation, control fish travelled progressively more distance over the test duration whereas High TAN, Hyperoxia and Hypoxia conditions showed lower and stable distance travelled. Such lower swimming activity under high TAN was described before in rainbow trout (Shingles et al., 2001) and under hypoxia conditions in common sole (*Solea solea*; Dalla Via et al. (1998)) and dogfish (*Scyliorhinus canicula*; Metcalfe and Butler (1984)) whereas hyperoxia was shown to lead to higher variability of the activity pattern in Atlantic salmon (Espmark and Baeverfjord, 2009). It is, however, important to note that behavioural responses under hypoxia were found to be clearly dependant on the intensity and duration of the hypoxia challenge and the species (Chapman and McKenzie, 2009). NH₃ is known to cause asphyxiation by reducing the blood oxygen-carrying capacity and hence alter the swimming performances reported above (Shingles et al., 2001; Camargo and Alonso, 2006). Indeed, decrease in oxygen or increase in TAN concentration both lead to reduced active metabolic rate (Muusze et al., 1998; Shingles et al., 2001) and may explain why exposed fish are being less active than controls. It seems that fish adopted a “wait and see” strategy consisting in minimizing energy expenditure and waiting for an improvement in water quality (van Raaij et al., 1996; Clingerman et al., 2007). Finally, concerning interindividual distances, during the 0-5 min period of novel environment in group, fish from Control and Hypoxia conditions expressed the same group cohesion whereas fish from high TAN and Hyperoxia conditions were closer to each other. Fish from Hyperoxia condition stayed closer during all test duration while both fish from High TAN and Hypoxia conditions displayed lower group cohesion than control fish from 60-65 to 90-95 min periods. Interestingly, Domenici et al. (2002) reported the same larger dispersion in Atlantic herring under O₂ saturation of 20 % and same results were observed in Atlantic salmon under O₂ saturation of 150 % (Espmark and Baeverfjord, 2009). Lower group cohesion was also observed in rainbow trout under other stress factor such as hypercapnia by Sadoul et al. (2017). When given the possibility, it is well known that fish are able to avoid stressful environment such as hypoxic waters, high ammonia or high CO₂ concentrations (Richardson et al., 2001; Clingerman et al., 2007; Skjæraasen et al., 2008; Herbert et al., 2010). Therefore we suggest that fish interindividual distance increases to maximize oxygen uptake (Domenici et al., 2017) and thus could be used as a relevant welfare indicator (Juell, 1995; Espmark and Baeverfjord, 2009). This behavioural strategy can also be perceived as a decrease in attention and/or used for saving energy for a better coping with stress favouring a return to a homeostatic state. Additional experiments are however required to fully understand the observed disruptions of the shoal cohesion but it overall fits well with the on-growing research effort about the effects of abiotic factors on fish group behaviour (Weetman et al., 1999; Domenici et al., 2002; Espmark and Baeverfjord, 2009; Colchen et al., 2017; Domenici et al., 2017; Sadoul et al., 2017; Colson et al., 2019). Concerning the HPI axis responsiveness, plasma cortisol concentrations are always high for European sea bass upon stress exposure since this species is known to be high cortisol responder (Rotllant et al., 2003; Samaras et al., 2016; Alfonso et al., 2019b). In undisturbed conditions, plasma cortisol values are expected to be around 100 ng.L$^{-1}$ but it can reach a value 10 fold higher upon stress (Samaras et al., 2018; Alfonso et al., 2019b). In addition to the confinement stress in the bathing tank, fish also experienced two handling stresses, one transfer between the rearing and the bathing tanks and then between the bathing and the experimental tanks explaining the high cortisol values measured in all conditions. Measured plasma cortisol concentrations were similar between fish exposed to Hyperoxia and control fish but were higher in fish exposed to Hypoxia and High TAN conditions than control. A similar increase in cortisol release was previously reported in Atlantic salmon following chronic exposure to ammonia (0.15 mg.L$^{-1}$, (Knoph and Olsen, 1994)) and hyperoxia (150 % O$_2$ saturation, (Espmark and Baeverfjord, 2009) or acute exposure to hypoxia (25 % of O$_2$ saturation) in rainbow trout (van Raaij et al., 1996). Behavioural disruptions observed in Hyperoxia treated fish did not translate in terms of cortisol values compared to control fish, suggesting the possible implication of other physiological mechanisms, such as plasma catecholamines as previously shown in rainbow trout (van Raaij et al., 1996; Gesto et al., 2013; 2015). Interestingly, within a species, individuals are known to differ from each other in terms of amplitude of primary stress response (e.g. cortisol and catecholamines) and, along with divergent behavioural responses, that defines individual coping styles (Castanheira et al., 2017). Therefore, it would be interesting in future studies to include complementary coping style characterizations to investigate the link between coping style, behavioural responses within a group and primary responses upon stress exposure. This would help in assessing whether different strategies co-exist to cope with these kinds of stressors within a fish group. After 2 h-exposure to any of the tested conditions (High TAN, Hyperoxia and Hypoxia), fish travelled less distance in novel tank diving test than control fish during the first 5 minutes in system water. Thereafter all fish reached the same activity level. Such behavioural recovery from hypoxia in European sea bass is rapid and similar to that reported in Nile Tilapia (*Oreochromis niloticus*, Xu et al. (2006)). To our knowledge, it is the first time that behavioural recovery from Hyperoxia and High ammonia concentration has been monitored. In addition to distance travelled, fish previously exposed to High TAN explored the top area more than control fish and decreased progressively time spent in top to reach control’s level after 20 min in system water. On the contrary, the two other conditions (*i.e.*, Hyperoxia and Hypoxia) explored progressively the top area in the same way than control fish. The fast release from bottom dwelling (or the search for access to water surface) observed in High TAN exposed fish resembled the surface swimming observed for nicotine-exposed fish. As explained before for the novel environment test in group situation, the lower anxiety-like behaviour observed in High TAN fish could also be the result of fish setting priority to cope with TAN instead of expressing psychological stress effects *i.e.* a relief of anxiety. **Conclusion** In conclusions, our results showed that thigmotaxis, swimming activity, group cohesion and bottom dwelling behaviour are reliable behavioural indicators of health and welfare status in European sea bass. Moreover, this study reports the fact that it is important to distinguish between stressors that could affect survival and psychological stressors such as handling or confinement alone. Besides cortisol, other molecular factors should be sought for to fully understand individual stress responses depending on the type and/or duration of stressors. Finally, the novel tank diving test seems to be sensitive for screening recovery state and thus better evaluate welfare status in farmed fish. **Acknowledgments** This work was supported by the French National Research Agency, project ERANET ANIHWA Win-Fish (ANR-14-ANWA-0008). SA received a PhD grant from Ifremer to conduct this research. Lucette Joassard, Christine Jarc, Didier Leguay, Mathieu Auvinet, Maxime Petitjean and Thibault Geoffroy from Ifremer technical staff are acknowledged for their help in conducting the experiments. We also thank the two anonymous reviewers for helpful comments on the previous version of the manuscript. References caged Atlantic salmon, based on a review of selected welfare indicators and intended for fish health professionals. Reviews in Aquaculture 6, 162-179. Captions Figure 1. Experimental protocol followed for fish exposure to different water qualities (stress condition) and behavioural and physiological measurements. Figure 2. Mean ± SEM of TAN and UIA-N (mg.L⁻¹) and oxygen saturation (% O₂) for High TAN, Hyperoxia and Hypoxia conditions during bathing period (at 0, 30 and 60 min) and at the start and end of novel environment challenge in group. Figure 3. Swimming characteristics in the novel tank diving test. Mean ± SEM of (A) time spent in top area in relation to the observation period (s); (B) total time spent in top area (s); (C) distance travelled in relation to the observation period (cm); (D) total distance travelled (cm); (E) number of transitions between top and bottom areas and (F) latency to enter in top area (s) in nicotine-bathed and control-conditions (n=24 per condition). (A, C) Tukey HSD post-hoc: *: p<0.05; **: p<0.01; ***: p<0.001. (B,D,E,F) Mann-Whitney U-test: ***: p<0.001. Figure 4. Spatial location of fish during the novel environment in group. Averaged heatmaps of fish spatial location (n=30 per condition) over the different time periods. From low (blue colour) to high location frequency (red colour). Figure 5. Swimming characteristics in the novel environment in group challenge. Mean ± SEM of (A) distance travelled (cm); (B) interindividual distance (cm); (C) proportion of time spent in different areas (%) for each condition (n=30 control, High TAN, Hyperoxia and Hypoxia). Tukey HSD post-hoc: different letters indicate significant differences between conditions within observation periods. Figure 6. Swimming characteristics in the novel tank diving test. Mean ± SEM of (A) time spent in the top area (s); (B) total time spent in the top area (s); (C) distance travelled (cm); (D) total distance travelled (cm); (E) number of transitions between the two areas and (F) latency to enter in the top area (s) post-stress for all conditions (n=20 control, n=20 High TAN, n=18 Hyperoxia; n=18 Hypoxia). Tukey HSD post-hoc: different letters indicate significant differences between conditions. **Figure 7.** Plasma cortisol concentration *post*-stress in the novel environment group challenge (Mean ± SD) for each condition (n=9 control, n=9 High TAN, n=9 Hyperoxia; n=10 Hypoxia). Mann & Whitney U-test: *: p<0.05; **: p<0.001 Figure 2 Oxygen saturation (%) vs. TAN concentration (mg L\(^{-1}\)) - Hyperoxia - Hypoxia - High TAN Start and End markers indicate time points for each condition. Figure 3 A) Time spent in top area (s) over 25 minutes. B) Time spent in top area (s) for Nicotine and Control. C) Distance travelled (cm) over 25 minutes. D) Distance travelled (cm) for Nicotine and Control. E) Number of transitions for Nicotine and Control. F) Latency to enter top area (s) for Nicotine and Control. Figure 4 Figure 5 A. Distance travelled (cm) B. Interindividual distance (cm) C. Proportion of time (%) Legend: - Control - High TAN - Hyperoxia - Hypoxia Graph C: - Centre area - Periphery area Legend for Graph C: - a - b - c - d Figure 6 A) Time spent in top area (s) B) Distance travelled (cm) C) Latency to enter top area (s) D) Number of transitions E) Latency to enter top area (s) Legend: - Control - High TAN - Hyperoxia - Hypoxia Significant differences are indicated by lowercase letters (a, b). Figure 7 Plasma cortisol concentration (µg.mL\(^{-1}\)) Control High TAN Hyperoxia Hypoxia 0 1 2 3 *** *
Big Data A New World of Opportunities Contents 1. Executive Summary ............................................................................................................. 3 2. Introduction .......................................................................................................................... 4 2.1. Political context .................................................................................................................. 4 2.2. Research and Big Data ..................................................................................................... 5 2.3. Purpose of the paper ........................................................................................................ 5 2.4. Approach ........................................................................................................................ 5 2.5. Document outline .......................................................................................................... 6 3. Big Data concept .................................................................................................................... 6 3.1. Definitions ....................................................................................................................... 6 3.2. Origins of the concept ..................................................................................................... 7 4. Economic and societal impact of Big Data: a new world of opportunities ....................... 8 5. Technical and scientific challenges ....................................................................................... 10 5.1. Big Data Analytics .......................................................................................................... 10 5.2. Context awareness ......................................................................................................... 11 5.3. Rethinking data visualization and human-computer interfaces ..................................... 11 5.4. Visual Analytics: how we look at data ............................................................................ 12 5.5. Data management performance and scalability ............................................................. 13 5.6. Correlation and Causality .............................................................................................. 13 5.7. Real time analytics and stream processing ..................................................................... 14 5.8. Distributed Storage ....................................................................................................... 15 5.9. Content Validation ........................................................................................................ 16 6. Big Data Business Ecosystem ............................................................................................... 16 6.1. An EU Big Data Business Ecosystem ............................................................................. 18 6.2. Big Data Market Places ................................................................................................. 19 7. Privacy and Big Data .............................................................................................................. 19 7.1. “Without appropriate privacy no benefits from using Big Data technology” ................. 19 7.2. A New Legislation ......................................................................................................... 20 7.3. Privacy Preserving Data Mining ..................................................................................... 21 8. SWOT analysis of the EU Software and Services industry in the context of Big Data ....... 21 8.1. Strengths ....................................................................................................................... 21 8.2. Weaknesses ................................................................................................................... 22 8.3. Opportunities ............................................................................................................... 22 8.4. Threats ......................................................................................................................... 23 9. Recommendations ................................................................................................................ 23 9.1. Technical aspects .......................................................................................................... 23 9.2. Business aspects ......................................................................................................... 24 9.3. Legal aspects ............................................................................................................... 25 9.4. Skills ............................................................................................................................. 25 1. Executive Summary The amount of available data has exploded in the past years because of new social behaviors, societal transformations as well as the vast spread of software systems. Big Data has become a very important driver for innovation and growth that relies on disruptive technologies such as Cloud Computing, Internet of Things and Analytics. Big Data is thus very important to foster productivity growth in Europe since it is affecting not only software-intensive industries but also public services, for example the health, administration and education sectors. A challenge for Europe is to ensure that software and services providers are able to deliver high quality services along the lines of the fast growing number of services and users. Providers of Software and Services must be able to ensure the protection of their users’ data (in terms of availability and use) while at the same time allowing the use of the information to improve the quality of the services they deliver. Users also want more personalised and more responsive applications without unsatisfied requests. The goal is to implement the vision of full-time availability of services and resources based on data everywhere for anyone, at all time. In this perspective, the flow of Big Data is a key enabler for the provision of resources anytime, anywhere, and the adaptation to demand. Big Data software and services generate value by supporting an innovative eco-system and by enabling completely new solutions that have not been possible before. The value lies in the applications based on advanced data-analysis on top of more general Big Data layers, semantic abstractions or network and physical objects virtualization. In this white paper, the European Technology Platform NESSI (Networked European Software and Services Initiative) seeks to contribute to the current European Big Data discourse, based on the expertise of its member community. NESSI offers a comprehensive view on technical, legal, social and market-related aspects of Big Data that have a direct impact on applications, services and software technologies practices. This paper addresses the challenges rising from the use of Big Data and how to overcome those in order to enable new technical and business opportunities for Europe’s software industry and economic sectors. The key points stressed in this paper seek to ensure that the necessary technical conditions and expertise of a skilled work force are available, together with the right business and policy environment in order for Europe to take advantage of these opportunities and regain its competitive position with respect to the rest of the world. As a result, NESSI brings forward the following recommendations, divided into four different, but highly interlinked sections: **Technical**: NESSI supports the need to direct research efforts towards developing highly scalable and autonomic data management systems associated with programming models for processing Big Data. Aspects of such systems should address challenges related to data analysis algorithms, real-time processing and visualisation, context awareness, data management and performance and scalability, correlation and causality and to some extent, distributed storage. **Business**: On the EU-level we need a mechanism to foster and structure information between key actors in the European "Big Data Ecosystem" which should be considered from a data process-centric perspective. A Big Data business ecosystem can only be built with a clear understanding of policies addressing legal and regulatory issues between countries, cross-enterprise collaboration issues and the nature of data sources. EU should establish European Big Data Centres of excellence (like Hack/Reduce in Boston) and fostering Open Source Big Data Analytics to make sure the benefits stay in the EU, with European developers, users and entrepreneurs. This should include the awareness of integrating existing private data with external data to enhance existing products and services. Legal: Within the context of the revised Data protection legal framework, NESSI suggests an in-depth privacy by design scheme, which is not imposing a ‘one size fits all’ rule but leaves flexibility to business in order to ensure that the economic potential of Big Data is cared for in a way that allows for evaluating and analysing data and use such data predicatively for legitimate business purposes, including identity verification and fraud detection and prevention. Skills: NESSI encourages the creation of new education programs in data science and supports the idea of creating a European Big Data Analytics Service Network to foster exchanges between data scientists and businesses and as a way up to building advanced data-analysis products within the software industry. NESSI stresses the importance of creating resources for using commoditized and privacy preserving Big Data analytical services within SME’s. 2. Introduction 2.1. Political context In recent years, Big Data has become a major topic in the field of ICT. It is evident that Big Data means business opportunities, but also major research challenges. According to McKinsey & Co 1 Big Data is “the next frontier for innovation, competition and productivity”. The impact of Big Data gives not only a huge potential for competition and growth for individual companies, but the right use of Big Data also can increase productivity, innovation, and competitiveness for entire sectors and economies. This is in line with the targets set out in the Europe 2020 Strategy aiming to foster a sustainable, smart and inclusive European economy, where the EU-flagship the Digital Agenda for Europe (DAE) has the overall aim to create a sustainable and economic European digital single market with a number of measures directed at the use of data sources in Europe. To be able to extract the benefits of Big Data, it is crucial to know how to ensure intelligent use, management and re-use of Data Sources, including public government data, in and across Europe to build useful applications and services. The Digital Agenda emphasizes the importance of maximizing the benefits of public data, and specifically the need for opening up public data resources for re-use (Action 3 of the Digital Single Market Pillar). Public Sector Information (PSI) is the single largest source of information in Europe. Its estimated market value is €32 billion. Re-used, this public data could generate new businesses and jobs and give consumers more choice and more value for money, as the DAE points out. The European Commission has already pushed for some actions at technical level (mainly related to data formats in order to promote interoperability and re-use) but also at regulatory and policy levels, by fostering transparency and availability of data and encouraging access. The EU Open Data strategy, which is an amendment of the Public Sector Information Directive, encourages more openness and reuse of public sector data 2. Even though the process is still in a very early stage there is still a need to analyse both sides of the problem as open data can be a threat for privacy. In addition, the European Commission is developing a Data Value Strategy which will address the entire data life cycle. NESSI seeks to contribute to the Data Value Strategy, based on the expertise of its members. NESSI offers a comprehensive view of key technical, market-related and social aspects which forms the Big Data landscape with specific attention to the position of Europe software industry and research. 1 McKinsey Global Institute, Big Data: The next frontier for innovation, competition and productivity (June 2011) 2.2. Research and Big Data There are currently a number of initiatives aimed at adjusting the research landscape to lodge the rapid changes taking place in the processing of data under the current and seventh framework programme for Research and Innovation, FP7. As an example, the Big Data research challenges under FP7, include 81 projects addressing a vast set of topics ranging from content creation & processing (including multimedia and games), "Big Data" analytics and real-time processing. In Horizon 2020, Big Data finds its place both in the Industrial Leadership, for example in the activity line “Content technologies and information management”, and the Societal Challenges, relating to the need for structuring data in all sectors of the economy (health, climate, transport, energy, etc.). Not surprisingly, Big Data is also important to the Excellent Science priority of Horizon 2020, especially to part I, sections 4.1 and 4.2, on scientific infrastructures and development of innovative high value added services. In addition, also other research areas will experience the growing role of the efficient use of data. For example, data from space observations have been specifically singled out as a resource to be exploited together with data from big medical studies. 2.3. Purpose of the paper The objective with this NESSI White Paper is to highlight selected aspects of Big Data that create particular opportunities, but also challenges for the software and services industry in Europe. Therefore, NESSI will address current problems and materialize opportunities associated to the use of Big Data, by applying a unifying approach, where technical aspects are aligned with business-oriented, regulatory and policy aspects. We will examine how Big Data actors can create a better momentum for Europe in terms of global competition. Thus, the overarching goal is to identify Big Data research and innovation requirements in the context of Horizon 2020. NESSI will also put forward policy recommendations of a more general character to provide input to the Commission Data Value Strategy. 2.4. Approach NESSI wants to impact the technological future by identifying strategic research directions and proposing corresponding actions. NESSI gathers representatives from industry (large and small), academia and public administration and is an ETP active at international level. NESSI closely monitors technology and policy developments of Big Data as it has a large impact on the software and services domain. In the beginning of this year, NESSI formed a Task Force consisting of Big Data experts from member companies and universities to coordinate the work with this white paper on Big Data. The NESSI Big Data task force further asked NESSI’s members to contribute to the Big Data white paper in order to support the ideas put forward regarding of the requirements of the Software and Services sector. --- 3 Article: “Big Data at your Service” (July 2012) 4 Answer to Parliamentary question, Neelie Kroes (23 July 012) The members were asked to answer ten questions distributed in an on-line survey. The responses from our members have been integrated into this document. 2.5. Document outline The paper firstly defines the Big Data concept and describes its origins and main characteristics (section 3). Section 4 discusses economic and societal impact of Big Data usage for applications and services. Section 5 introduces some of the technical and scientific challenges associated to collecting, capturing, curating, searching, sharing, analysing and visualizing data faced by the software industry to exploit Big Data. Section 6 provides an overview of the main actors and market trends in the European Big Data business ecosystem. From a societal perspective, section 7 analyses opportunities and challenges related to privacy, with a special emphasis on business impact but also regulatory concerns. In the last parts of the paper, we present a brief SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis for the Software and Services Industry in Europe, within the context of Big Data. We conclude the white paper by bringing forward a number of recommendations identified by NESSI. 3. Big Data concept 3.1. Definitions Big Data is a notion covering several aspects by one term, ranging from a technology base to a set of economic models. In this white paper, the following definition of Big Data will be applied: "Big Data is a term encompassing the use of techniques to capture, process, analyse and visualize potentially large datasets in a reasonable timeframe not accessible to standard IT technologies. By extension, the platform, tools and software used for this purpose are collectively called “Big Data technologies”. Big Data is not a new concept, and can be seen as a moving target linked to a technology context. The new aspect of Big Data lies within the economic cost of storing and processing such datasets; the unit cost of storage has decreased by many orders of magnitude, amplified by the Cloud business model, significantly lowering the upfront IT investment costs for all businesses. As a consequence, the “Big Data concerns” have moved from big businesses and state research centres, to a mainstream status. The total number of respondents was 34, which means that the results from the survey are not used as basis for the arguments put forward in this paper, but rather as support with additional points, to the ones already raised by the main authors in the NESSI Big Data task force. 3.2. Origins of the concept A decade ago, data storage scalability was one of the major technical issues data owners were facing. Nevertheless, a new brand of efficient and scalable technology has been incorporated and data management and storage is no longer the problem it used to be. In addition, data is constantly being generated, not only by use of internet, but also by companies generating big amounts of information coming from sensors, computers and automated processes. This phenomenon has recently accelerated further thanks to the increase of connected devices (which will soon become the largest source of data) and the worldwide success of the social platforms. Significant Internet players like Google, Amazon, Facebook and Twitter were the first facing these increasing data volumes “at the internet scale” and designed ad-hoc solutions to be able to cope with the situation. Those solutions have since, partly migrated into the open source software communities and have been made publicly available. This was the starting point of the current Big Data trend as it was a relatively cheap solution for businesses confronted with similar problems. Meanwhile, two parallel breakthroughs have further helped accelerate the adoption of solutions for handling Big Data: - The availability of Cloud based solutions has dramatically lowered the cost of storage, amplified by the use of commodity hardware. Virtual file systems, either open source or vendor specific, helped transition from a managed infrastructure to a service based approach; - When dealing with large volumes of data, it is necessary to distribute data and workload over many servers. New designs for databases and efficient ways to support massively parallel processing have led to a new generation of products like the so called noSQL databases and the Hadoop map-reduce platform. The table below summarizes the main features and problems connected to handling different types of large data sets, and explains how Big Data technologies can help solve them. <table> <thead> <tr> <th>Aspect</th> <th>Characteristics</th> <th>Challenges and Technology responses</th> </tr> </thead> <tbody> <tr> <td>Volume</td> <td>The most visible aspect of Big Data, referring to the fact that the amount of generated data has increased tremendously the past years. However, this is the less challenging aspect in practice.</td> <td>The natural expansion of internet has created an increase in the global data production. A response to this situation has been the virtualization of storage in data centres, amplified by a significant decrease of the cost of ownership through the generalization of the cloud based solutions. The noSQL database approach is a response to store and query huge volumes of data heavily distributed.</td> </tr> </tbody> </table> --- ### Velocity This aspect captures the growing data production rates. More and more data are produced and must be collected in shorter time frames. The daily addition of millions of connected devices (smartphones) will increase not only volume but also velocity. Real-time data processing platforms are now considered by global companies as a requirement to get a competitive edge. ### Variety With the multiplication of data sources comes the explosion of data formats, ranging from structured information to free text. The necessity to collect and analyse non-structured or semi-structured data goes against the traditional relational data model and query languages. This reality has been a strong incentive to create new kinds of data stores able to support flexible data models. ### Value This highly subjective aspect refers to the fact that until recently, large volumes of data where recorded (often for archiving or regulatory purposes) but not exploited. Big Data technologies are now seen as enablers to create or capture value from otherwise not fully exploited data. In essence, the challenge is to find a way to transform raw data into information that has value, either internally, or for making a business out of it. Building end-to-end platforms that can efficiently process data of all dimensions is a challenge on its own and new business opportunities appeared for: - Traditional IT vendors who want to provide integrated, industrial grade solutions - Small- and medium sized businesses who can offer specialized products or services around open source software - Professional services companies who can provide training and missing skills like “data scientists” As of today, almost all major software and service vendors have, in one way or another, jumped on to the Big Data bandwagon as it is seen as an emerging and important market. ### 4. Economic and societal impact of Big Data: a new world of opportunities According to the McKinsey Global Institute report on Big Data from 2012, the most developed regions, such as Europe, have the biggest potential to create value through the use of Big Data. The enormous economic impact of Big Data is further shown in another study7 prepared by the Centre for Economics and Business Research (CEBR), estimating the value of Big Data to the UK economy alone, being £216 billion and 58,000 jobs in the next 5 years. Big Data is further expected to add more than €250 billion a year to the European economy. --- 7 Center for Economics and Business Research: Data Equity – Unlocking the value of big data, p. 4 ff. (April 2012) public sector administration. Thus, the whole European Union could benefit from the cumulative financial and social impact of Big Data. Big Data analytics has started to impact all types of organisations, as it carries the potential power to extract embedded knowledge from big amounts of data and react according to it in real time. We exemplify some of the benefits by exploring the following different scenarios. New technologies produce massive streams of data in real time and space that along time can make it possible to extract patterns of how the structure and form of the city changes and the way in which citizens behave. In such “smart cities”, data gathered by sensors integrated with transport data, financial transactions, location of users, social network interaction will provide an entirely new dimension to thinking about how cities function. The danger associated with this aspect, relates to privacy and will be elaborated further down. Managing data in an effective way opens a wide field of opportunities for cities contributing to the improvement of services for citizens, such as: “on demand” and context-sensitive transportation strategies, optimized management of energy demand, more "holistic" and "preventive" health care approaches, development of new services such as e-voting, etc. Various branches of experimental science generate vast volumes of experimental data. Petabytes (PB) of data per day is not uncommon in these fields (e.g. research in particle physics produces vast amounts of experimental data within short time frames). Fulfilling the demands of science requires a new way of handling data. Optimal solutions provided by Big Data technologies to analyse and properly compare disperse and huge datasets would provide huge benefits in terms of discoveries in experimental sciences. Big Data in healthcare is associated with the exploding volume of patient-specific data. A prime example is medical imaging where even small pathological features measuring just a few millimeters can be detected in magnetic resonance imaging and in CT scans. Doctors, already under significant time and cost pressure, will find it increasingly difficult to conduct their own analyses and error-free evaluations of the growing volume of data and images. They urgently need the support of automated solutions, which are increasingly based on the application of machine learning to large sets of example images. An even more dramatic increase in data volume is expected with the introduction of modern molecular analysis to medical praxis, for example by the increasing use of next-generation DNA sequencing. Naturally, imaging data and molecular data need to be evaluated in the context of the complete available patient information, such as all clinical data but also family history. Data protection and information security are particularly sensitive issues when it comes to medical data. If there is even the slightest perception that health records could fall into the wrong hands, the corresponding services will not be adopted. The amount of mobile data traffic is expected to grow to 10.8 Exabyte per month by 2016. This tremendous growth is driven mainly by the increased usage of smart phones and tablets. Big Data technology is needed in order to realize some advanced use cases in today’s mobile networks and will be certainly required in future networks. Big Data is important for example for managing and operating mobile networks and gaining insights into the network with the goal to improve the network quality; which includes isolation and correlation of faults within the network, support of security related detection and prevention mechanisms, traffic planning, prediction of hardware maintenance, or the calculation of drop call probability. --- 8 McKinsey Global Institute, Big Data: The next frontier for innovation, competition and productivity, p.2. (2012) 9 Forrester: Mobile is the new face of engagement, (February 2012), The changes brought by new web social media technologies mainly refer to the appearance of new types of content providers and new types of content, often referred to as ‘new media’. New media is giving the power of speech to the citizens who can now very easily report, blog and send short text messages (e.g., tweets), and rapidly creating new content of huge amounts. Traditionally, in the area of news media, conventional journalism has been the main trend, operating with standard news collection and broadcasting procedures while mediating mainstream types of content (e.g., politics, sport, economy, culture, health) from authoritative sources. Since a few years however, new Internet web technologies have appeared and have disrupted this business process. Traditional news media are getting more and more overcome by the rise of web news services. In terms of associated business and economic activity, many software and services vendors already rely on Online Analytical Programming (OLAP) systems to perform their market or sells analysis. For this usage, Big Data technologies do not provide a clear advantage, and can be at best viewed as enablers to help scale legacy systems. However, in order to move beyond this state and access finer details, past simple statistics, different approaches that are best supported by Big Data technologies are required. In the following section, NESSI puts forward a number of areas where such technical and scientific challenges are becoming critical. 5. Technical and scientific challenges 5.1. Big Data Analytics Because the current technology enables us to efficiently store and query large datasets, the focus is now on techniques that make use of the complete data set, instead of sampling. This has tremendous implications in areas like machine learning, pattern recognition and classification, to name a few. Therefore, there are a number of requirements for moving beyond standard data mining techniques: - a solid scientific foundation to be able to select an adequate method or design - a new algorithm (and prove its efficiency and scalability, etc.) - a technology platform and adequate development skills to be able to implement it; - a genuine ability to understand not only the data structure (and the usability for a given processing method), but also the business value. As a result, building multi-disciplinary teams of “Data scientists” is often an essential means of gaining a competitive edge. More than ever, intellectual property and patent portfolios are becoming essential assets. One of the obstacles to widespread analytics adoption is a lack of understanding on how to use analytics to improve the business. The objects to be modelled and simulated are complex and massive, and correspondingly the data is vast and distributed. At the same time, the modelling and simulation software --- LaValle et al: Big Data, Analytics and the Path From Insights to Value, (Dec 2010) solutions are expected to be simple and general, built on the solid foundations provided by a few robust computational paradigms and naturally oriented towards distributed and parallel computing. Hence, new methodologies and tools for data visualization and simulation are required. 5.2. Context awareness Due to the increasing mobility of users and devices, context-awareness increases in importance. A suitable and efficient content- and context-aware routing of data is needed in many cases. Facing existing infrastructures and Big Data setups many solutions focus on processing and routing all data at once. For example, in manufacturing existing data has no relation to the context about the user’s history, location, tasks, habits schedule, etc. Concepts for taking the spatial users into account are a major challenge. The goal is to take the context into account for data that is not related to a user or context and present the right data to the right people and devices. Applying contextual awareness can thus be a suitable approach to improve the quality of existing problem solving. In the context of Big Data, contextualisation can be an attractive paradigm to combine heterogeneous data streams to improve quality of a mining process or classifier. In the last years, context awareness has widely demonstrated its crucial role to achieve optimized management of resources, systems, and services in many application domains, from mobile and pervasive computing to dynamically adaptive service provisioning. Context-aware Big Data solutions could exploit context awareness to focus on only some portions of data (at least in first approximation) by keeping high probability of hit for all application-relevant events, with manifest advantages in terms of cost reduction and complexity decrease. Research on industrial applicability on how to achieve the best trade-off between limitedness of the considered portions and probability of hits still necessitate significant investigation and research efforts. In addition, context awareness is demonstrated to be useful to reduce resource consumption by concentrating Big Data generation processes (e.g., monitoring of real-world situations via cyber-physical systems) only on the sources that are expected to be the most promising ones depending on currently applicable (and often application-specific) context. For instance, “monitoring greediness” can be context-aware, thus permitting to switch off or decrease the duty cycle of expensive (in terms of power consumption, traffic bandwidth, ...) sensors; industry-oriented research along this guideline is needed, with promising opportunities of cost/complexity reduction of Big Data solutions. 5.3. Rethinking data visualization and human-computer interfaces Data visualisation is vital if people are to consume Big Data effectively. The reports generated from the analytics can be thought of as documents. These documents frequently contain varying forms of media in addition to textual representation. Even if textual representation alone is used, the sheer amount of it in large and complex documents requires carefully designed presentation for a digital screen. When trying to represent complex information and the associated rationale, tasks, social networks and conceptual networks on screen(s), the design issues multiply rapidly. The interface to such information needs to be humane\textsuperscript{11}, i.e., responsive to human needs and considerate of human frailties. Frailties and needs of knowledge workers are closely linked. They need relevant information in a just-in-time manner but too much information, which they cannot search efficiently, can hide that which is most relevant. They need to understand the relevance and relatedness of information but frequently have other work commitments which stop them from striving to establish relevance and relatedness. Other considerations are important for data visualisation like visual clutter\textsuperscript{12} which can lead to a degradation of performance at some task. A primary measure of visual clutter is Feature Congestion (based on Rozenholtz’ Statistical Saliency Model) which is based on the notion that the more cluttered a visual image is the more difficult it is to add contextually relevant attention-grabbing items. 5.4. Visual Analytics: how we look at data Visual analytics aims to combine the strengths of human and electronic data processing. Visualization, whereby humans and computers cooperate through graphics, is the means through which this is achieved. Seamless and sophisticated synergies are required for analyzing Big Data, including a variety of multidimensional, spatio-temporal data, and solving spatio-temporal problems. Visual analytics is a relatively new term; it was introduced in research agenda books published in the USA\textsuperscript{13} and EU\textsuperscript{14}. However, the kinds of ideas, research and approaches that are now termed visual analytics emerged much earlier. The main idea of visual analytics is to develop knowledge, methods, technologies and practice that exploit and combine the strengths of human and electronic data processing. Visualization is the means through which humans and computers cooperate using their distinct capabilities for the most effective results. The key features of visual analytics research include: - Emphasis on data analysis, problem solving, and/or decision making; - Leveraging computational processing by applying automated techniques for data processing, knowledge discovery algorithms, etc.; - Active involvement of a human in the analytical process through interactive visual interfaces; - Support for the provenance of analytical results; - Support for the communication of analytical results to relevant recipients As the majority of Big Data is dynamic and temporally referenced, it is necessary to take into account the specifics of time\textsuperscript{15}. In contrast to common data dimensions, which are usually “flat”, time has an inherent semantic structure. By convention, time has a hierarchical system of granularities organized in different calendar systems. Another key issue is supporting analysis at multiple scales. There is much to do for visual analytics in order to change the traditional practice in analysis, focusing on a single scale. Appropriate scales of analysis are not always clear in advance and single optimal solutions are unlikely to exist. Interactive visual interfaces have a great potential for facilitating the empirical search for the acceptable scales of analysis and the verification of results by modifying the scale and the means of any aggregation. \textsuperscript{14} (13) Daniel Keim, Jörn Kohlhammer, Geoffrey Ellis and Florian Mansmann (Eds.) Mastering The Information Age – Solving Problems with Visual Analytics. Eurographics, 2010 To realize this potential, we need to know more about appropriate visual representation of different types of data at different spatial and temporal scales. There is a need to develop corresponding analysis supporting interaction techniques, which should enable not only easy transitions from one scale or form of aggregation to another but also comparisons among different scales and aggregations. 5.5. Data management performance and scalability Performance and scalability are central technical issues in order to deal with the huge volume of data to be stored and processed by Big Data systems and technologies. Two primary groups of technical issues call for significant advancements and industrially applicable research results. On the one hand, there is the need for novel effective solutions dealing with the issue of data volume per se, in order to enable the feasible, cost-effective, and scalable storage and processing of enormous quantities of data. Promising areas that call for further investigation and industrially applicable results include effective non-uniform replication, selective multi-level caching, advanced techniques for distributed indexing, and distributed parallel processing over data subsets with consistent merging of partial results, with no need of strict consistency at any time. On the other hand, another relevant performance/scalability issue worth of significant efforts relates to the need that Big Data analysis is performed within time constraints, as required in several application domains. The possibility to define quality constraints on both Big Data storage (for instance, where, with which replication degree, and with which latency requirements) and processing (for instance, where, with which parallelism, and with which requirements on computing resources) should be carefully taken into account. Currently, process analysis in areas such as Business process management (BPM) is disconnected from data-based analyses in areas such as Data Mining and Business Intelligence. Bridges focusing on process mining will be also essential for progression of the Big Data theme. 5.6. Correlation and Causality The causality of events (e.g. the unusual hot weather led to increased sales of soft drinks – where the event we are interested in is the increased sales of soft drinks and the cause was the unusually hot weather) in processes is of interest to enterprises (regardless of whether these are internal or external to the enterprise). In more complex scenarios causality will usually be latent across collections of data and spread across the four “V” dimensions of big-data. For example, sudden increases of Tweets consisting of unstructured mentions of flu symptoms as well as structured contextual data such as location and demographics may shortly precede a spree of medicinal purchases and stock exhaustion in particular channels and regions. In this contrived example there is a predicted correlation between Tweets and medicinal stock levels but the causal claim is that a statistically significant number of ‘medical problem’ Tweets (the cause) results in a ‘medical solution’ prediction about stock (the event). Research is needed to discover these kinds of latent causality patterns and enable causal chain exploration supporting people to make better informed decisions in shorter time. When enterprise data, knowledge management, decision making and so forth, are in view, the notion of cause\textsuperscript{16,17} is equally crucial. The challenge is manifold particularly when considering the mix of structured/unstructured data. Therefore, any Big Data strategy needs to focus on a few areas: - Discovering and modelling causality in structured data (reasonably well understood from the Data Mining perspective) - Discovering and modelling causality in unstructured data (not well understood but growing work in Artificial Intelligence and Machine Learning etc.) - Integrating unstructured causality models with structured causality models (not well understood but growing work in System Dynamics, Complex Event Processing, etc.) Causality Modelling has had most attention in Computer Science from the perspective of known, well-defined data i.e. structured data. The Data Mining community has a long history (for the Computer Science discipline) that has built on the even more historical disciplines of Statistics, Operational Research, and Probability. Such a history provides a solid start for Causality Modelling. However, a particularly difficult subset of Causality Modelling is unstructured data e.g. text, multimedia (whether user generated content or not). This is in contrast to structured data e.g. point-of-sale transactions, stock prices, sensor readings. As well as the large volume of data there are other challenges. The unstructured data must be structured or pre-processed into a form amenable for analysis. A further subset of unstructured data which is of particular interest to a broad range of businesses is text data. Text data is prevalent in practically every business domain imaginable, from Customer Relationship Management to Marketing to Product Design and so forth. Complex, valuable knowledge involving topics, products, designs, relationships, opinions, sentiment and argumentation, to name but a few, is locked in text data. The potential outcomes of causality discovery for the business enterprise will be dependent on machine processing due to the Big Data four V’s and the need for near real-time analysis to support human decision makers and more accurate simulations and predictions. ### 5.7. Real time analytics and stream processing In many business scenarios it is no longer desirable to wait hours, days or weeks for the results of analytic processes. Psychologically, people expect real-time or near real-time responses from the systems they interact with. Real-time analytics is closely tied to infrastructure issues and recent move to technologies like in-memory databases is beginning to make ‘real-time’ look achievable in the business world and not just in the computer science laboratory. Handling large amounts of streaming data, ranging from structured to unstructured, numerical to microblogs streams of data, is challenging in a Big Data context because the data, besides its volume, is very heterogeneous and highly dynamic. It also calls for scalability and high throughput, since data collection related to a disaster area can easily occupy terabytes in binary GIS formats and data streams can show bursts of gigabytes per minutes. The capabilities of existing system to process such streaming information and answer queries in real-time and for thousands of concurrent users are limited. Approaches based on traditional solutions like Data Stream Management Systems (DSMS) and Complex Event Processors (CEP), are generally insufficient for the \textsuperscript{16} Pearl, J. Causality: Models, Reasoning and Inference. 2\textsuperscript{nd} ed. Cambridge University Press. (2009) \textsuperscript{17} http://www.causality.inf.ethz.ch challenges posed by stream processing in a Big Data context: the analytical tasks required by stream processing are so knowledge-intensive that automated reasoning tasks are also needed. The problem of effective and efficient processing of streams in a Big Data context is far from being solved, even when considering the recent breakthroughs in noSQL databases and parallel processing technologies. A holistic approach is needed for developing techniques, tools, and infrastructure which spans across the areas of inductive reasoning (machine learning), deductive reasoning (inference), high performance computing (parallelization) and statistical analysis, adapted to allow continuous querying over streams (i.e., on-line processing). One of the most open Big Data technical challenges of primary industrial interest is the proper storage/processing/management of huge volumes of data streams. Some interesting academic/industrial approaches have started to mature in the last years, e.g., based on the Map Reduce model to provide a simple and partially automated way to parallelize stream processing over cluster or data centre computing/storage resources. However, Big Data stream processing often poses hard/soft real-time requirements for the identification of significant events because their detection with a too high latency could be completely useless. New Big Data-specific parallelization techniques and (at least partially) automated distribution of tasks over clusters are crucial elements for effective stream processing. Achieving industrial grade products will require: - New techniques to associate quality preferences/requirements to different tasks and to their interworking relationships; - New frameworks and open APIs for the quality-aware distribution of stream processing tasks, with minimal development effort requested by application developers and domain experts18. 5.8. Distributed Storage It is an obvious fact that there are increasingly distributed data sets being used for Big Data analytics. Even within one organization there tends to be a number of data sets that require analysis. If this is expanded to a supply chain in one particular business domain and then to cross-domain supply chains the distributed nature of data sets increases. Including also the volume and velocity of the data and performing meaningful analytics becomes a major challenge. Then, if security and legal issues are considered, the distributed nature of data sets presents one of the most complex problems to solve. One approach which displays promise is the use of data marts. However, data marts are not yet designed with the features of Big Data in mind. Another approach is the use of Big Data Analytics Agents (BDAA). The agents perform a specific function or set of functions on data sets. They are dispatched to appropriate locations and must be security cleared by the receiving data set. Once they have performed their analytics the data set then verifies the agents’ findings before letting it return to its sending location. BDAA’s could then be designed for the specific features of Big Data e.g. BDAA’s that sit for some period of time on data streams or BDAA’s that specifically analyse video for predefined features. 18 In addition, the availability of such open APIs can help in reducing the entrance barriers to this potentially relevant market, by opening the field to small/medium-size companies, by reducing the initial investments needed to propose new stream processing-based applications, and by leveraging the growth of related developers/users communities. 5.9. Content Validation Validating the vast amount of information in content networks is a major challenge, since there is a very large number of different types of sources, such as blogs, social networking platforms, or news sites with social networking functionalities, and different types of content, such as articles, comments, tweets, etc. Furthermore, the complexity of human language is such that it is not easy to derive validation rules that apply to all different discussion subjects. The vast amount of data that exists today, and the frequency with which it can be updated, render the validation task very difficult and make complex rules which require great computational resources infeasible. Therefore, there is a need to derive simple rules for validating content, and leverage on content recommendations from other users. The recommending users must themselves be assessed on the basis of trust and reputation criteria. Further, there is a need for learning algorithms to update rules according to user feedback. Machine learning algorithms can be an efficient solution for extracting patterns or rules for Web documents semi-automatically or automatically. 6. Big Data Business Ecosystem A business ecosystem, first defined by James F Moore19, is “An economic community supported by a foundation of interacting organizations and individuals.”20 In this regard, an ecosystem does not yet exist in Europe for Big Data. However, from at least one perspective a Big Data ecosystem (removal of ‘business’ is deliberate) does exist in many industries in a very simple form. For example, within an aerospace ‘ecosystem’ there will be a vast amount of data used across complex supply chains about materials, construction methods, testing, simulation, and so forth. Such data is moved from system to system in the various processes according to defined standards and within regulation. It is also analysed to establish patterns, failures, standards, and so forth. Consider another example, fraud detection21. Public sector fraud for 2011-2012 cost the UK tax payer £20.3 billion and private sector fraud was £45.5 billion, of which £16.1 billion was retail fraud. In 2008-9 the National Fraud Initiative traced £215m in fraud, error and overpayments using standard analytics. How much more could be pre-empted and traced if there was a Big Data Business Ecosystem? Moving from such specific Big Data ecosystems to a Big Data Business Ecosystem will not be a straightforward evolution. The problem for Big Data is small patterns22 “precisely because so many data can now be generated and processed so quickly, so cheaply, and on virtually anything, the pressure is to be able to spot where the new patterns with real added value lie in their immense databases and how they can best be exploited for the creation of wealth and the advancement of knowledge. Small patterns matter because they represent the new frontier of competition, from science to business, from governance to social policies.” --- 21 Cebr Report for SAS: Data Equity: Unlocking the Value of Big Data, Centre for Economics and Business Research Ltd (April 2012) This gives an idea about some of the trends that are emerging and that could provide the basis for a Big Data Business Ecosystem. The first one refers to **data science and that associated skills are in high demand**. The education challenge is not only to teach students fundamentals skills such as statistics and machine learning, but also appropriate programming ability and visual design skills. Individuals who have a little imagination, some basic computer science and enough business acumen will be able to do more with data either for their own business or as part of a pool of talented “data scientists”. Organisations – and governments - able to achieve this multi-disciplinary cross-fertilisation will have a tremendous advantage as, ultimately, this could result in a self-feeding cycle where more people start small and are able to work their way up to building advanced data-analysis products and techniques used as the foundation for the next generation of data products built by the next generation of data scientists. **A European Big Data Analytics Service Network** to improve skills capacities within the software industry could be highly beneficial for achieving this aim. Secondly, the **generalisation of machine learning** is crucial for creating a viable Big Data Business Ecosystem. Consumers - and advertisers - want more personalisation and more responsive applications: the prospect of writing models that discover patterns in near real-time is so appealing that it’s difficult to imagine a company not considering it as a new revenue stream. While machine learning has been recently promoted to the front-line, it does not mean it’s easy to do. To the contrary, effective machine learning requires a strong academic background and the ability to transform a mathematical model into a marketable product. As a third point, the **commoditisation of Big Data platforms** plays an important role for any Big Data Business Ecosystem. The technological improvements in infrastructure, database, telecoms, and so forth are nothing without applications that can take advantage of them, and two approaches are driving the market. The first one is to make Big Data accessible to developers by making easy to create applications out of pre-packaged modules tied to a Big Data backend. This is in essence the promise of delivering “Data as a Service” or “Algorithms as a Service” in a Cloud environment. The second approach is to find a convincing use case for Big Data like face recognition, user behaviour analysis or network security, and turn it into a commercial product that companies can start using off the shelf. But there are further trends that have appeared in the context of creating a Big Data Business Ecosystem, such as: - **Cloud services** expand the state of the art architectural design and implementation pattern, into business relationships between service providers and consumers. IT personnel need to develop new skills that come close to those required from data scientists. - **Increasing Cross-Enterprise Collaboration** is a business necessity in many instances, but it requires sharing, exchanging, and managing data across enterprise walls. Erbes et al state that such cross-enterprise collaboration “will create new ecosystems that rely on effectively and selectively enabling access to the required systems and services.” It is also helpful to understand that Big Data has a social life. It moves through processes often in a transformed state and can have different importance at different stages of a process. Davenport et al state that organisations capitalising on Big Data differ from traditional data analysis in three ways: --- 1. They pay attention to data flows as opposed to stocks. 2. They rely on data scientists and product and process developers rather than data analysts. 3. They are moving analytics away from IT function and into core business, operational and production functions. We propose that, in light of the above, a Big Data Business Ecosystem should be considered from a process-centric perspective. Data exist, whether at rest or in motion, within processes that span traditional LoB’s and sectors. Such processes will have a variety of resources, from people to facilities, which relate to the data. Delineating the processes and resources is a vital step in evolving immature Big Data Business Ecosystem to more mature levels. Consider the following example. An automotive production line makes use of several different tools. These tools have an uptime of 99.8%. The production line process is owned by the automotive manufacturer and they monitor the tool data to ensure maximum efficiency. The tool manufacturer has a cross cutting process related to tool maintenance and receives constant data streams from the tools which they analyse for potential performance issues and service events. The production line tooling is producing data that are relevant to both processes. Some of the data will be more relevant to one or the other process. In the above contrived example it may be straightforward to see the security and regulatory issues. However, real life scenarios will be much more complicated. Business processes will span countries which frequently have different regulations regarding data, they will span organisations and they will span various data sources. We propose that a Big Data Business Ecosystem can be built with a clear understanding of and policies addressing, the following: - Legal and regulatory issues between countries. - Cross-enterprise collaboration issues. - Nature of data sources and the basic translations to be applied to them. ### 6.1. An EU Big Data Business Ecosystem At the highest level an EU Big Data business ecosystem must accommodate two scenarios, the first scenario indicating **unhindered innovation supported by open data access.** Open access to Big Data should not necessarily result from a clear and well understood roadmap. Opening access to certain Big Data sources enabling innovation will help drive an ecosystem of SMEs. The second scenario would support **innovation by principled collaboration between business process owners.** An EU Big Data business ecosystem is an important factor for commercialisation and commoditisation of Big Data services. Especially for enterprises, an ecosystem requires several roles such as data integrators, Big Data service providers, real-time data vendors, and so forth. The segments for typical Big Data vendors are mainly split into the four: applications, analytic tools, data management, and infrastructure. Within an international ecosystem several roles have to be applied. The service provider/vendor is the first actor and basically the owner of the data. The provider can be split into the private sector, public sector and individuals. Of course, each of them has specific challenges and motivations for joining the ecosystem. A catalyst is required to serve legitimacy, which could be the role of, e.g., the government. For example, business analytics based on trade data would become easier for the EU by joining multiple geographic groups. Also, consumers with a clear benefit are additional actors. Finally, data scientists and experts are necessary due to specific technical skills and domain knowledge. For building a working ecosystem the benefit for all actors must be clear. For example, companies must profit from offering and/or consuming services. Consequently, a challenge will become the orchestration of such services. Furthermore, the EU has to deal with special challenges due to the variety of public and private instances across country boarders. The major challenge for a broader ecosystem will be privacy and security. This is a crucial success factor for all actors to take part. Especially for the EU the instrumentation of standards across the borders is an additional gap to be fulfilled. 6.2. Big Data Market Places A further perspective in conceiving of a Big Data Business Ecosystem is that of Big Data Market Places. Despite the value that is hidden in Big Data sets, there are certain challenges associated with the cost and complexity of publishing such data as well as the cost and complexity of consuming and utilising the data. Many data providers, who have stockpiled vast amounts of interesting data, struggle with the problem of finding ideas for creating novel services using their data, identifying what makes their data relevant for potential consumers, and deploying solutions for rapid integration of data for loosely defined services. The lack of a sustainable data marketplace ecosystem for Big Data, where producers of data can effectively disseminate their data and consumers can interact with the providers in new ways, enabling efficient delivery of new applications and services, hinders the development of novel data-driven business models in the Big Data domain. Current data markets face various problems such as data discovery, curation, linking, synchronization and distribution, business modelling, sales and marketing. This situation calls for new technologies, infrastructure, approaches, and methodologies to create and sustain a Big Data marketplace ecosystem. This will require, amongst others, improving current practices of publishing and consuming Big Data; tool-supported methodologies for efficient publication, dissemination and consumption of data in data marketplaces; scalable data dissemination and communication approaches between data providers and consumers on the data marketplaces. 7. Privacy and Big Data 7.1. “Without appropriate privacy no benefits from using Big Data technology” With the advent of Big Data, systematic collection, storage and analysis of personal data has dramatically increased. From internet logs, user information can be extracted that is accessible for surveillance and marketing purposes; identity management tools are now used on the Internet to track the identity of users; in the physical world cameras are used for surveillance; mobile phones send location information to the network providers; debit and credit card payment systems reveal the amounts spent and stores visited. Store loyalty cards allow analysing consumer behaviour; and social media allow user-to-user contact and access to pictures, videos and movies. An increasing number of companies, established global players, SME’s and start-ups, built their business models on using and selling user profiles generated from these data sources. Data mining tools sift through the data to find patterns in large collections of personal data, to identify individuals and to predict preferences and interests. These patterns and predictions are stored in company databases and combined with new data. Also governments have increasing use for analysing and exchanging information about their citizens. Overall, collection, storage, analysis and usage of personal data are now part of our everyday life at all levels of society. NESSI members do not believe that realizing the promise of analytics requires the sacrifice of personal privacy. A truly modernized legal framework should provide for a high level of data protection while leaving sufficient flexibility to business to innovation, create jobs and growth and remaining competitive at a global level. 7.2. A New Legislation The Data Protection Directive dates from 1995, back to a time when the internet use was not widespread. So far, the 27 EU Member States have implemented the 1995 rules differently. This results in divergences in enforcement. In January 2012, the European Commission proposed a comprehensive reform of the EU's 1995 data protection rules to strengthen online privacy rights and boost Europe's digital economy.\(^{26}\) A single law, so it is hoped, will do away with the current fragmentation and costly administrative burdens, However, the benefits of greater harmonisation are at risk of being outweighed by the administrative burden and subsequent costs the draft regulation would impose on business without actually enhancing the protection of the user; the proposed text is adding administrative burden and not cutting red tape; As currently drafted, the regulation represents a step backwards for competitiveness in the European Union at a time of economic crisis when business is facing many other challenges. Newly proposed obligations are too complex to be properly understood, coupled with constraints on implementation that limits flexibility needed by business to efficiently utilize technologies – including big data usages –to remain competitive in a global economy. Many of the proposed provisions were drafted with a specific context in mind without considering the consequences for the wider industry. Overly prescriptive requirements inhibit the goal of the Regulation to be technology neutral. We and the upcoming generation need to be able to use new technologies to address Europe’s most difficult societal and economic problems. With a, all too rigid, legal framework we will not be able to live up to this promise. In this context we are especially concerned about the ‘one-size fits all’ approach for consent and the wording of Article 20 of the draft which is putting even the legitimate use of analytics/big data (or here profiling) at risk. The need to ensure that the provisions relating to “profiling” do not prevent businesses from being able to evaluate and analyse data and use such data predicatively for legitimate business purposes, including identity verification and fraud detection and prevention. An in-depth privacy by design scheme, which is not imposing a ‘one size fits all’ rule but leaves flexibility to business could go a long way in delivering both the promise that Big Data applications can bring while providing strong safeguards for data protection. This must be coupled with strong enforcement and severe fines for stakeholders abusing the scheme and being deliberately and notoriously non-compliant with data protection rules. \(^{26}\) European Commission Press release: Commission proposes a comprehensive reform of data protection rules to increase users’ control of their data and to cut costs for businesses (January 2012) [available online: http://europa.eu/rapid/press-release_IP-12-46_en.htm?locale=en ] 7.3. Privacy Preserving Data Mining. There is a research direction called privacy-preserving data mining that aims to reconcile the tension between Big Data and privacy. The upcoming legislation, and the sentiments of at least parts of the public, makes privacy-preserving methods a topic of strong interest. It can be categorized as follows. In privacy-preserving data publishing the challenge is to publish the data with appropriate suppression, generalisation, distortion, and/or decomposition such that privacy of individuals is not compromised and yet the disclosed data is useful for analytical purposes. A large body of work inspired by k-anonymity has flourished in this area. In privacy-preserving data mining, the main assumption is that private data is collected for the purpose of consolidating the data and analysing it with one or more data mining algorithms. The collector is not a trusted party, so data is subjected to a random disconcertion as it is collected. In privacy-preserving pattern publishing, the central question addressed is how to publish frequent patterns without revealing sensitive information about the underlying data. In pattern hiding the main concern is how to transform the data in a way that certain patterns cannot be derived (via mining), while others can. In addition, secure multiparty mining over distributed datasets, indicates that data on which mining is to be performed is partitioned, horizontally or vertically, and distributed among several parties. The partitioned data cannot be shared and must remain private but the results of mining on the “union” of the data are shared among the participants. Although a number of interesting approaches have been developed, these methods are not generally known and not in widespread use in industry. Attempts are needed to make them better known and to bring them to practice. 8. SWOT analysis of the EU Software and Services industry in the context of Big Data Using Big Data as a new asset is very a promising idea for the European economy, especially for the large base of SME’s. The following analysis underlines strengths, weaknesses, opportunities and threats (SWOT) with respect to the European software industry and how they could use big data analytics to improve their products and services. This section especially addresses the SME initiative on analytics aiming to help European SMEs acquire the competences and resources they need to develop innovative content and data analytics services27. 8.1. Strengths - Europe has a large group of commercially successful SME’s focusing on market driven innovation within their niche and with a focus on export. In Germany, they are known as “hidden champions” but they exist in other European countries as well. Because these SME’s operate in very narrow niches they have to focus on global markets to work on an economic scale. Those companies benefit from exclusive insights about their global customers to build market oriented products and services. - There is deep knowledge about local markets and local customer problems and ability to develop customized products such as language dependent products, legislation dependent products. --- • Effective (although fragmented) research and development networks between universities, research centres and SME’s are established and has been referred to as a “role model for decentralized R&D”. • There is a well-established understanding in export oriented companies to deliver high-value products and services (e.g. “premium cars”) by using innovation networks. • Growing interest from SME’s using cloud computing and software services 8.2. Weaknesses • While US-based companies like Yahoo, Google, or Twitter are widely recognized for their activities in Big Data, very few research organizations, including SMEs, are known for their activities and initiatives in this field in Europe. • SME’s lag behind larger enterprises in taking up the Big Data challenges, especially compared to the US. • In most SME’s there is not enough understanding on how to gain new insights by using data analytics concerning their customers, products and services. • The capabilities to develop an individual data strategy, to select and integrate the right data sources and to use effectively big data analytics for leveraging exclusive insights for product and business development are critically underdeveloped. • No wide spread knowledge about freely available data ("getting new insights by merging different data sources") • Analytical Big Data services for SME’s within Europe are currently non-existing 8.3. Opportunities • Rising customer demands in Europe for smarter products, higher individualization, and mass customization. • Europe’s SME’s can benefit by enhancing their products and services with big data analytics and privacy by design, e.g. offering preventive maintenance services in the utilities industry, usage-based analytics for distant product development, self-learning behaviors for energy optimization (e.g. Nest thermostat) or new business models thanks to better usage insights (like Rolls-Royce and their power by the hour performance based contracting). • Europe’s SME’s could benefit enormously by reducing copyright infringements with smart networked products and services. • Better use of freely available data. • Levelling the playing field by giving access to formerly very demanding analytical tools through commoditization. • Developing new products and services enhanced with Big Data analytics and privacy by design, developing products adapted to European privacy standards Established innovation networks could reduce skill shortages by spreading knowledge with online trainings and generating hands-on expertise based on commoditized analytical services. 8.4. Threats - Globally there is a fast growing knowledge about using data as an asset class for leveraging the industrial competitiveness, for example in China, India. - There is a massive venture-capital driven development in the US to commoditize formerly complex big data analytics for the mainstream market. www.bigml.com is an example of the commoditization efforts around Hadoop. SME’s in Europe have no alternatives to choose comparable services from European vendors. - Insufficient capabilities of European companies to scale to the world market. - There are serious concerns among European businesses about using big data analytics neglecting European privacy standards and expectations. In the meantime, foreign competitors take their market shares by pushing their own de-facto standards in respect to privacy. 9. Recommendations In summary, there are several aspects to consider in order for Big Data to provide a beneficial impact on society and to create growth and jobs for Europe. There is especially added value in the application layer of Big Data which is why, it is important to bring together the domain knowledge with the analytical expertise needed to identify meaningful correlations of data. In extension, there is a need to develop predictive use cases, and to support real-time processing and analysis. Another important aspect is the protection of privacy related data. In the section below, NESSI aims to bring forward a number of important aspects which need to be addressed in any research programme or policy initiative on Big Data. The recommendations have been divided into four highly interlinked sections. 9.1. Technical aspects NESSI supports the need to direct research efforts towards developing highly scalable and autonomic data management systems associated with programming models for processing Big Data. Aspects of such systems should address challenges related to real-time processing, context awareness, data management and performance and scalability, correlation and causality and to some extent, distributed storage. In detail, NESSI suggest the following directions for future research efforts. 1. Align the ability of data analysis algorithms towards the new constraints generated by the treatment of massive data collections (heterogeneity, multimodality, size etc.) 2. Concerning context awareness, research on industrial applicability on how to achieve the best trade-off between limitedness of the considered portions and probability of hits is highly important and still necessitate significant investigation. 3. With regards to visual analytics, it is important to promote the need for understanding the relevance and relatedness of information. 4. There is a need to know more about appropriate visual representation of different types of data at different spatial and temporal scales. It is important to develop corresponding analysis tools. supporting interaction techniques, which should enable not only easy transitions from one scale or form of aggregation to another, but also comparisons among different scales and aggregations. 5. Areas that call for further investigation and industrially applicable results within the context of management performance and scalability include effective non-uniform replication, selective multi-level caching, advanced techniques for distributed indexing, and distributed parallel processing over data subsets with consistent merging of partial results, with no need of strict consistency at any time. 6. The possibility to define quality constraints on both Big Data storage (for instance, where, with which replication degree, and with which latency requirements) and processing (for instance, where, with which parallelism, and with which requirements on computing resources) should be carefully taken into account in future research activities. 7. In relation to modelling causality, research efforts would be directed towards discovering and modelling causality in structured data (reasonably well understood from the Data Mining perspective), discovering and modelling causality in unstructured data (not well understood but growing work in Artificial Intelligence and Machine Learning etc.) and finally, integrating unstructured causality models with structured causality models (not well understood but growing work in System Dynamics, Complex Event Processing, etc.). 8. New Big Data-specific parallelization techniques and (at least partially) automated distribution of tasks over clusters are crucial elements for effective real-time stream processing. Achieving industrial grade products will require new techniques to associate quality preferences/requirements to different tasks and to their interworking relationships together with new frameworks and open APIs for the quality-aware distribution of stream processing tasks, with minimal development effort requested by application developers and domain experts. 9. Regarding validation, it is necessary to derive simple rules for validating content, and leverage on content recommendations from other users. Machine learning algorithms can be an efficient solution for extracting patterns or rules for Web documents semi-automatically or automatically. 9.2. Business aspects 10. NESSI calls for a mechanism on EU-level which will foster and structure information and business exchange between key actors in the European “Big Data Ecosystem”. This Big Data Business Ecosystem should be considered from a process-centric perspective. NESSI underlines the importance of fostering industrial knowledge transfer by establishing European Big Data Centres of excellence (like Hack/Reduce in Boston). 11. NESSI stresses the importance of fostering Open Source Big Data Analytics to make sure the benefits stay in the EU, with European developers, users and entrepreneurs. 12. NESSI suggests raising awareness about the possibilities of integrating existing private data with external data to enhance existing products and services. NESSI further advocates that a Big Data 28 In addition, the availability of such open APIs can help in reducing the entrance barriers to this potentially relevant market, by opening the field to small/medium-size companies, by reducing the initial investments needed to propose new stream processing-based applications, and by leveraging the growth of related developers/users communities. business ecosystem can only be built with a clear understanding of, and policies addressing legal and regulatory issues between countries, cross-enterprise collaboration issues and the nature of data sources and the basic translations to be applied to them. 13. NESSI believes that the European Commission should move beyond the Open Data Initiative, towards an interoperable data scheme, including protocols that help data processing from heterogeneous sources. This could serve as an incentive for a normalized way to manage data related to people, etc. 9.3. Legal aspects It is apparent that the Big Data topic raises legal concerns related to the fair and liable use of data. To address these issues, NESSI puts forward the following recommendations. 14. There is a strong need to ensure that the provisions relating to “profiling” do not prevent businesses from being able to evaluate and analyse data and use such data predicatively for legitimate business purposes, including identity verification and fraud detection and prevention. Within the context of the revised Data protection legal framework, NESSI suggests an in-depth privacy by design scheme, which is not imposing a ‘one size fits all’ rule but leaves flexibility to business. 15. NESSI supports the idea that any Big Data analytics commoditization should be developed with respect to European privacy regulations (privacy by design) as well as Cloud Computing strategies. NESSI recommends developing such privacy by design regulations within already existing standardisation bodies. 16. Although a number of interesting approaches have been developed with regards to privacy preserving data mining, these methods are not generally known and not in widespread use in industry. NESSI advocates for making them better known and to bring them to practice. 9.4. Skills As mentioned in the chapter about a Big Data eco-system, skills for data science and associated skills are in high demand. 17. NESSI encourages the set up of education programs on data science. The education challenge is not only to teach students fundamentals skills such as statistics and machine learning, but also appropriate programming ability and visual design skills. 18. NESSI supports the idea of creating of a European Big Data Analytics Service Network (EBDAS) to increase exchanges between data scientists and businesses in order to improve skills capacities within the software industry which will lead to the next generation of data-analysis products and applications. 19. NESSI stresses the importance of creating resources for using commoditized and privacy preserving Big Data analytical services within SME’s. This includes the creation of Big Data Centres, offering hands-on trainings, generating hands-on expertise for SME’s using Big Data for their products and services, and leveraging access to large-scale compute clusters, online-trainings, specialized consulting.
Crop raiding by primates in particular and wild animals in general is a significant source of people-forest conflict around the Budongo Forest Reserve, Uganda. Crop loss to wild animals undermines local support for conservation efforts in this area. Patterns of primate crop raiding were studied over a period of 14 months in six villages (five adjacent to the Budongo Forest Reserve and one that is approximately 3,500 m from the forest edge). Data were collected via a questionnaire survey. Additional information was obtained from the relevant local government offices. Chimpanzees *Pan troglodytes*, baboons *Papio anubis*, other monkeys, bush pigs *Potamochoerus porcus* and porcupines *Hystrix cristata* were reported by farmers to be the major causes of crop losses by wildlife. Of farmers, 73% reported suffering crop damage caused by primates, and 79% considered baboons to be the most destructive of all crop raiding species. Drought, insect pests, poor sowing, plant diseases and accidental fires were other sources of crop losses to farmers, though the risk of crop damage particularly by primates is perceived as the most serious potential cause of losses. Using chimpanzees as a case study, patterns of crop damage across the year are compared with seasonal fluctuations in availability of wild foods. **Key words:** Budongo Forest Reserve, conservation, crop raiding, farmers, primates, Uganda, wild animals Mnason Tweheyo*, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5014, N-1432 Ås, Norway - e-mail: tweheyo@forest.mak.ac.ug Catherine M. Hill, Department of Anthropology, School of Social Sciences & Law, Oxford Brookes University, Gipsy Lane Campus, Oxford, OX3 OHP, UK - e-mail: cmhill@brookes.ac.uk Joseph Obua, Department of Forest Biology and Ecosystems Management, Makerere University, P.O. Box 7062 Kampala, Uganda - e-mail: obua@forest.mak.ac.ug *Present address: Department of Forest Biology and Ecosystems Management, Makerere University, P.O. Box 7062, Kampala, Uganda **Corresponding author:** Mnason Tweheyo **Received 15 May 2003, accepted 3 May 2004** **Associate Editor:** Göran Ericsson Conservation is often difficult where densely settled agricultural lands are adjacent to protected areas inhabited by animals that pose a potential threat to farmers’ crops, as is the case for many forest reserves and national parks in Africa and Asia (e.g. Dudley et al. 1992, De Boer & Baquete 1998, Naughton-Treves et al. 1998). In partic- ular, primate crop raiding and human conflict is wide spread in many parts of Africa. For example, around Bwindi Impenetrable Forest National Park, Uganda (CARE 1994), around protected areas in Tanzania (Newmark et al. 1994), around Ituri Forest, the Democratic Republic of Congo (Mubalama 1996), and around Maputo Elephant Reserve, Mozambique (De Boer & Baquete 1998). Especially, baboons *Papio anubis* are notorious for their crop raiding activities throughout Africa (Else 1991). At present it is generally accepted in Africa that farmer-wild animal conflict has increased over the last 30 years mostly because of increased amounts of land being converted to agriculture (Hill 1997). Around the Budongo Forest Reserve, Uganda, where the risk of crop damage by primates is perceived to be significant, local communities are hostile to conservation programmes (Reynolds 1992, Johnson 1996). In this case crop loss to primates undermines local support for conservation efforts. Studies on human settlements have provided evidence of increased complaints of damage to crops by wild animals in western Uganda (Aluma et al. 1989, Obua et al. 1998). Despite the frequency of primate-human conflict, until recently few studies have analysed factors concerning primate crop raiding (Naughton-Treves 1997, Knight 1999, Hill 2000, Saj et al. 2001, Sprague 2002). The objective of our study was to gather information on the farmers’ knowledge of patterns of crop raiding to help conservation authorities, government and local people to devise more effective mitigation measures. In particular, we identified the primates regarded by farmers as causing most damage, the crops they raid, and seasons of raiding. We also compare availability of forest and crop foods with farmers’ reports of chimpanzee *Pan troglodytes* raiding patterns. Availability of forest fruits has been used to indicate availability of chimpanzee food in the forest because chimpanzees are primarily frugivores with more than 70% of their diet consisting of fruits (e.g. Reynolds & Reynolds 1965, Wrangham et al. 1994, Tweheyo & Obua 2001), and are reported to feed on other foods only when fruits are scarce (Wrangham 1977, Naughton-Treves et al. 1998, Newton-Fisher 1999). We could not compare farmland food with forest foods for other primates because of insufficient information on the seasonal availability of natural food resources important to other primate species in the Budongo Forest Reserve. In this paper, we compare patterns of chimpanzee food in the forest with patterns of crops in the farms to assess whether chimpanzee raiding behaviour occurs as a consequence of shortfall in the availability of forest foods. For baboons, other monkeys, bush pigs *Potamochoerus porcus* and porcupines *Hystrix cristata*, we record their patterns of crop raiding based on interviews with farmers only. Since permanent methods to prevent crop raiding are not easily affordable by local farmers (Poole et al. 2002), our findings highlight specific seasons when crop protection methods should be a primary focus for farmers rather than trying to implement strategies year round that may be expensive and require much labour. **Methods** **Study area** The Budongo Forest Reserve (BFR), Masindi District, western Uganda, lies between 1°35’ and 1°55’N and 31°8’ and 31°42'E, and has an average altitude of 1,100 m a.s.l. The reserve was gazetted as a central forest reserve in 1932. It comprises a mixture of tropical high forest with a large population of mahoganies, woodlands and savanna grasslands believed to be capable of supporting forest. It is the largest forest reserve in Uganda, covering about 825 km², 53% of which is a continuous tropical forest; the remainder comprises grassland communities (Hamilton 1984, Howard 1991). Regional records from the nineteenth century describe a vast forest surrounded by scattered agricultural settlements (Paterson 1991). Traditionally, farmers protected their field crops against damage from wild animals by hunting and trapping the animals in and around their fields (Paterson 1991). This was regarded as an effective way of protecting crops because it had an additional benefit of providing households with meat, which was partly perceived to compensate for crop losses (Vansina 1990). Up to the middle of the 1900s, crop damage by wild animals, particularly by elephants *Loxodonta africana* made some arable land uninhabitable (Paterson 1991, Hill 1998). As a consequence of increasing elephant-people conflict in the middle of the 1900s, elephants were killed locally in large numbers (Brooks & Buss 1962). The elephants that survived migrated to the neighbouring Murchison Falls National Park. Thus there are no elephants at present within in the BFR. Daily temperature and rainfall data recorded by the Budongo Forest project field station from 1993 to 2001 demonstrate that rainfall at this site exhibits a bimodal pattern, but the forest is generally wet year round (Fig. 1). The mean monthly rainfall is 139 ± 67 mm (± SD), and there is a relatively constant minimum temperature with a monthly mean of 20.9 ± 1°C (± SD). The precipitation bars depict a dry season between December and February, and in this period temperatures rise up to 31°C. The conversion of forested areas for agricultural use in western Uganda is closely correlated with human population growth. Human population density around Budongo more than tripled during 1960-2000 (NEMA 1999, Masindi District Profile 1989-2000). Most farmers cultivate two major crops, and sometimes three during years with high precipitation. Farmers cultivate a mixture of subsistence crops; sugarcane and tobacco are sometimes grown for cash income. The rapid population growth in western Uganda has resulted in land scarcity and has left Budongo Forest Reserve and a few other forests as the last refuges for wildlife. Budongo Forest Reserve is important globally for its high biodiversity, ranking third in overall importance for Uganda’s forests (Howard et al. 1997). There are approximately 465 species of trees and shrubs, though the forest is dominated by the stinkwoods *Celtis africana*, *C. gomphophylla*, *C. mildbraedii*, and *C. zenkeri*, mahogany *Khaya anthotheca*, and ironwood *Cynometra alexandri* (Plumptre 1996). In addition, there are five species of diurnal primates, chimpanzee, black and white colobus monkey *Colobus guereza occidentalis*, baboon, blue monkey *Cercopithecus mitis stuhlmanii* and red-tailed monkey *C. ascanius schmidtii*. **Data collection** Three parishes, i.e. Kabango, Nyabyeya and Nyantonzi, on the southern border of the Budongo Forest Reserve (Fig. 2) were selected for household questionnaire surveys. Six villages: Kapeka III, Binamira II and Wafala in Kabango, Nyakafunjo and Nyabyeya II in Nyabyeya, and Kanyege in Nyantonzi were selected. Apart from Binamira II (approximately 3,500 m from the forest boundary), all other villages share a common boundary with the Budongo Forest Reserve. There are many parishes and villages that surround the Budongo Forest Reserve, but due to inadequate time and logistical constraints, we only interviewed farmers from six villages, which were located in three parishes. The five villages that share a common border with Budongo Forest Reserve were chosen randomly from the list of the villages that border the forest. We assigned each village that borders the forest a number, we inserted the village numbers in the box and then we chose the surveyed villages randomly by picking their corresponding numbers from the box. Except Binamira II, which was selected specifically because, though far from the Budongo Forest Reserve, it is surrounded by forest patches. Data were collected between June 2000 and August 2001 using open-ended questionnaire interviews with households distributed among the six villages. Secondary data were obtained from wildlife conflict data books maintained by subcounty chiefs, Budongo Forest Project, Budongo Ecotourism Project, Nyabyeya Forestry College, Uganda Forest Department and Masindi District Vermin Control Department. Data on availability of chimpanzee forest foods were gathered via an ecological survey of forest food. A total of 144 interviews were accomplished; 78 men and 66 women. Of the people interviewed 72% were exclusively farmers, 11% were employed by Kinyara Sugar works, 8% were employed by the Uganda Forest Department, 4% were pit sawyers, 3% were carpenters. **Figure 1.** Mean monthly temperature (in °C) and rainfall (in mm) in the Budongo Forest Reserve, based on a yearly average for the period 1993-2000. Data obtained from the Budongo Forest project. **Figure 2.** The Budongo Forest Reserve and location of the study parishes of Kabango, Nyabyeya and Nyantonzi along the southern border of the forest reserve. and 2% were business people. In each interview, an adult member of the household was interviewed. In the six villages, there was an average of 56 households, and we interviewed 24 households (about 43%) per village. Households were chosen through random sampling. The subcounty chief of Budongo County had a list of all households in each parish and village, and from this list we chose our study households randomly. We looked at the list of households in each village and assigned each household a number. Then we inserted the household numbers in the box and later picked their corresponding numbers from the box randomly. The sampled households in each village were representative of the randomly chosen numbers from the box. The household member to be interviewed (man or woman) depended on the member who was available at the time of the interview. The age of the farmers interviewed ranged from 15 to 70, but the greatest percentage (33%) were between 40 and 49 years of age. Most interviews were carried out in Kiswahili, but we sometimes used English, Runyoro or Luo. To minimise biases from farmers’ perceptions, which is always embedded in people’s personal history and sometimes even in researchers’ thinking, the following measures were taken: 1. with the help of a resident research assistant and the subcounty chief, we disclosed to the community what the research was about and its intentions through the village chairpersons. We talked with the chairperson of each village, and then the village chairperson talked to the village members. We clarified that the research was meant for scientific and academic purposes, and that it had no legal or political implications; 2. we formed a committee, which consisted of the subcounty chief, the parish chairpersons and the village chairpersons, whom we worked with to recast the questionnaire. In this committee we avoided questions that were considered taboos in this community and factors considered private; 3. to avoid any content bias we crosschecked information given by direct observation, asking different people and reviewing literature. Farmers in the area reported to know the type of damage caused by particular animals. They believed that they were able to differentiate between damage caused by primates and damage caused by bush pigs or porcupines. Demographic, household and cropping data were collected from participants as well as information about animals raiding crops, the time(s) of the year when crop raiding occurs, extent of crop damage experienced by individual farmers, frequency of animals visiting farms, protection methods adopted against crop raiding animals, and other causes of crop losses. Initially farmers were asked to rate the crop losses they incur from different species and also across the seasons using a scale of 1-6, where 1 was equivalent to 'little or no damage' and 6 represented 'most severe damage'. For the purposes of analysis we compressed the 1-6 ranking scores used by farmers into three categories: 'severe damage' (3), 'modest damage' (2) or 'minimal damage' (1) by combining pairs of consecutive ranks, e.g. ranks 1 and 2 were combined to give a final rank of (1) equivalent to 'minimal damage' to generate an index of perceived severity of crop raiding. We then related the farmers’ severity index response to crop raiding with time and total number of crops in the field. We also asked farmers to rank all causes of crop loss that they experience on a scale of 1-6 as above to determine the degree to which farmers consider crop damage by wildlife as a significant cause of loss. Categories included were: drought, fire, insect pests, plant diseases, poor sowing and wildlife. Again these factors were grouped according to farmers’ perception as: a) cause greatest loss, b) cause modest loss, c) cause least loss, as outlined above. Each category of perception was analysed by scoring it against the cause of crop damage. After scoring each cause of crop damage in the three groups (greatest loss, modest loss and least loss), we weighed them by addition in each category (drought, fire, insect pests, plant diseases, poor sowing and wildlife) for analytical purposes to get total scores. With total scores, we assessed the single greatest cause of crop loss in accordance with farmers’ perception. Phenological sampling for fruit availability was carried out between June 1999 and June 2001 in circular plots (radius: 20 m) which were established systematically along eight line transects. Each transect was 2 km long. The sample plots were laid along each transect at intervals of 100 metres, giving a total of 160 sample plots along transects. In addition, one sample plot was laid out at a random position at 500 m distance on each side of the line transect, giving a further 16 random sample plots. Only tree species that were known to be edible to chimpanzees were monitored in both systematic and random sample plots. The Budongo Forest Project has records of trees known to be edible to chimpanzees. A total of 176 sample plots were surveyed, and 521 individual trees representing 29 species belonging to 15 families were monitored. Fruit trees were identified as those individuals with at least a 10-cm diameter at breast height (DBH) following the method of Chapman et al. (1992). Fruit availability was recorded twice a month. Scan sampling (Altmann 1974) was used to record... chimpanzee diet in the forest. Chimpanzee groups were followed from dawn to dusk between June 2000 and August 2001. During this period M. Tweheyo followed the chimpanzees for 176 days. Scans were made at 30-minute intervals to record the activities of each visible individual in the food trees. During this process all types of food eaten by chimpanzees were recorded: flowers (FW), insects (IS), buds (B), fruits (F), pith (PI), bark (BK), seeds (SE), prey (PE), nuts (NT), soil (SO) and wood (W). Scan sampling data were used to determine the different foods eaten by chimpanzees in different months. Our study compares only direct observations of forest and cultivated food for chimpanzees. Information about other animals is based on interviews with farmers only. Chimpanzees, baboons, red-tailed monkeys and blue monkeys have all been observed feeding on cultivated foods during this and a previous study (C.M. Hill, unpubl. data). Data were analysed using SPSS version 8.0 (1997). Results Raiding animals, season of raiding and food in the main forest Locally farmers consider crop raiding by primates, bush pigs and porcupines to be a major cause of crop loss. Of the farmers, 93% reported crop loss from primates, bush pigs and porcupines while 73% of farmers reported crop losses due to primate raiding. Five wild animals are listed as significant threats to crops (Table 1). Farmers’ reports of the months in which wild animals raided their farms varied significantly ($\chi^2 = 32.24, df = 11, P < 0.05$). Baboons and bush pigs were considered by farmers to be the most destructive wild animals (see Tables 1 and 3). Based on farmers’ responses, the most severely raided crops in the field varied significantly with months; ($\chi^2 = 55.71, df = 40, P < 0.05$). The months of severe crop raiding by all problem animals (Table 2) were positively related ($R^2 = 0.77, P = 0.001$) to months with many crops in the field (Fig. 3). The only contradictory response about severity of crop raiding was with farmers who planted sugarcane *Saccharum officinarum*; they expressed severe raiding problems during December, January and February, which coincides with the period of fruit scarcity in the forest. When forest fruits are scarce, chimpanzees feed on a range of other foods (Fig. 4), including leaves, flowers, pith, bark and seeds. There were no data available on forest foods eaten by other crop raiding species, therefore we cannot say with utmost certainty whether this reflects a period of low availability of forest foods for all these animals. However, since | Season | Most severe | Severe | Moderately severe | Mildly severe | Least severe | Scanning data used to determine the different foods eaten by chimpanzees in different months. Our study compares only direct observations of forest and cultivated food for chimpanzees. Information about other animals is based on interviews with farmers only. Chimpanzees, baboons, red-tailed monkeys and blue monkeys have all been observed feeding on cultivated foods during this and a previous study (C.M. Hill, unpubl. data). Data were analysed using SPSS version 8.0 (1997). Results Raiding animals, season of raiding and food in the main forest Locally farmers consider crop raiding by primates, bush pigs and porcupines to be a major cause of crop loss. Of the farmers, 93% reported crop loss from primates, bush pigs and porcupines while 73% of farmers reported crop losses due to primate raiding. Five wild animals are listed as significant threats to crops (Table 1). Farmers’ reports of the months in which wild animals raided their farms varied significantly ($\chi^2 = 32.24, df = 11, P < 0.05$). Baboons and bush pigs were considered by farmers to be the most destructive wild animals (see Tables 1 and 3). Based on farmers’ responses, the most severely raided crops in the field varied significantly with months; ($\chi^2 = 55.71, df = 40, P < 0.05$). The months of severe crop raiding by all problem animals (Table 2) were positively related ($R^2 = 0.77, P = 0.001$) to months with many crops in the field (Fig. 3). The only contradictory response about severity of crop raiding was with farmers who planted sugarcane *Saccharum officinarum*; they expressed severe raiding problems during December, January and February, which coincides with the period of fruit scarcity in the forest. When forest fruits are scarce, chimpanzees feed on a range of other foods (Fig. 4), including leaves, flowers, pith, bark and seeds. There were no data available on forest foods eaten by other crop raiding species, therefore we cannot say with utmost certainty whether this reflects a period of low availability of forest foods for all these animals. However, since <table> <thead> <tr> <th>Table 2. Season of crop raiding by wild animals, farmers’ claims to times of crop damage, and cropping patterns around the Budongo Forest Reserve.</th> </tr> </thead> <tbody> <tr> <td><strong>Season</strong></td> </tr> <tr> <td>-------------</td> </tr> <tr> <td>Early dry season (June, July &amp; November)</td> </tr> <tr> <td>Early wet season (March &amp; August)</td> </tr> <tr> <td>Late dry season (February)</td> </tr> <tr> <td>Late wet season (May &amp; October)</td> </tr> <tr> <td>Peak dry season (December &amp; January)</td> </tr> </tbody> </table> diets for wild animals can overlap, scarcity of chimpanzee foods in the forest may indicate scarcity for other sympatric primates. In Budongo forest there are more fruiting trees in the wet season. When we compared the number of farmers' reporting crop damage and the number of chimpanzee fruiting trees in any month (see Fig. 4), there was a positive relationship between the number of fruiting trees and crop raiding across the year ($R^2 = 0.69$, $P < 0.001$). This confirmed our personal observations that the months of severe crop raiding are not necessarily months of limited chimpanzee food in the forest, with the exception of periods when chimpanzees are reported to raid sugarcane. Thus crop-raiding behaviour would appear to be linked more to availability of preferred crops rather than to scarcity of wild food resources. While raiding crops, chimpanzees adopt more stealthy behaviours than when they are feeding in the forest, and they rarely move up to 500 m into the hinterland. It is mainly the adult chimpanzees that raid crops; females with infants rarely risk moving into crop-land. **Type of crops grown and frequency of crop damage** Bush pigs and porcupines raided farms only at night thus people guarded their fields at night. Guarding was the most common method used to chase away primates, ![Figure 3](https://bioone.org/journals/Wildlife-Biology-11_3-2005) Figure 3. Number of the 144 farmers interviewed responding to severe times of crop raiding (A), and relationship between index of crop raiding severity as calculated from most severe to little damage as shown in Table 2 and total number of crops in the field (B). Most severe months of crop raiding ranked as 6, severe as 5, moderately severe as 4, mildly severe as 3, least severe as 2 and little or no crop damage as 1. See Table 3 for crop names. ![Figure 4](https://bioone.org/journals/Wildlife-Biology-11_3-2005) Figure 4. Food types eaten by chimpanzees during different months in the Budongo Forest Reserve recorded between June 2000 and August 2001 (A), and relationship between number of farmers responding to crop raiding and total number of chimpanzee food trees fruiting in the Budongo forest (B). Number of trees fruiting was recorded between June 1999 and June 2001 based on monthly averages for two years. Number of farmers responding to crop raiding is based on their response to different months. *: Other food items include seeds, wood, soil, pith, prey, nuts, buds, insects and bark. Data are based upon equivalent sampling efforts for all food items throughout the year. bush pigs and porcupines from their crops as is the case for other studies (Hill 1997, Naughton-Treves 1998). Young and old people spent long hours scaring away animals, and there is no government intervention to help them. However, it is important to bear in mind that this is based on information largely obtained from farmers rather than independent observation. Therefore, we cannot rule out possible biases associated with farmers focusing on what happens in their fields when they think they have most loss. A total of 12 different crops were reported to be raided by wild animals (Table 3). Sugarcane was the only cash crop that primates raided year round. Crop damage frequency as reported by farmers varied significantly among the most destructive animal species ($\chi^2 = 94.7$, df = 2, P < 0.001). Baboons raided a wide range of crops (see Table 3), and farmers indicated that baboons raided some crops at all stages of growth from sowing/planting up to harvesting. Chimpanzees raided ripe fruits of mango *Mangifera indica*, pawpaw *Carica papaya* and sugarcane. Damage to sugarcane tended to increase during the dry season when all other crops had been harvested and there were relatively few chimpanzee fruits in the forest. Most of the crops were harvested during the early dry season, although some crops such as cassava *Manihot esculenta* persisted during the dry period (see Table 2). In general, farmers considered crop damage to be greatest during the harvesting time or just before harvesting when crops are mature (see Fig. 3 and Table 2). **Age of farmers, time spent in the area and other causes of crop losses** Most of the farmers are recent immigrants and 35% have lived in the Budongo subcounty for less than 10 years (Fig. 5). There was a significant difference between age of respondent and time spent living in the area ($\chi^2 = 95.86$, df = 30, P < 0.001) but no linear association (Spearman’s correlation coefficient: $r^2 = 0.14$, P < 0.1) between the two variables. The lack of linear association between farmers’ age and time spent living in the area may show that there has been increased immigration locally in recent times. Farmers report that competition for land has reduced forest cover and increased raiding by wild animals. Indeed, 93% of the farmers interviewed consider that crop raiding by wild animals has increased in the last 10 years. It is not possible to verify whether this is actually the case or not. However, farms from which crop raiding is reported to be a problem are often within 100 m from the forest boundary. Previous studies have already demonstrated the link --- ### Table 3. Type of crops grown, raiding animals and number of farmers reporting the vulnerability of various growth stages of crops. <table> <thead> <tr> <th>Crop</th> <th>Scientific name</th> <th>Animal species</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> <th>Stage of damage</th> <th>Frequency</th> </tr> </thead> <tbody> <tr> <td>Sugarcane</td> <td><em>Saccharum officinarum</em></td> <td>Chimpanzees</td> <td>34</td> <td>Mature</td> <td>40</td> <td>All</td> <td>10</td> <td>All</td> <td>4</td> <td>Young</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Mango</td> <td><em>Mangifera indica</em></td> <td>Baboons</td> <td>16</td> <td>Ripe fruits</td> <td>6</td> <td>Fruits</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Pawpaw</td> <td><em>Carica papaya</em></td> <td>Bush pigs</td> <td>10</td> <td>Ripe fruits</td> <td>4</td> <td>Fruits</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Beans</td> <td><em>Phaseolus vulgaris</em></td> <td>Monkeys</td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Cassava</td> <td><em>Manihot esculenta</em></td> <td>Porcupines</td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Maize</td> <td><em>Zea mays</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Finger millet</td> <td><em>Eleusine coracana</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Sweet potato</td> <td><em>Ipomoea batatas</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Tomato</td> <td><em>Solanum lycopersicum</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Yam</td> <td><em>Calocasia esculenta</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Ground nuts</td> <td><em>Arachis hypogaea</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> <tr> <td>Cabbage</td> <td><em>Brassica oleracea</em></td> <td></td> <td></td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> <td>-</td> <td></td> </tr> </tbody> </table> --- © WILDLIFE BIOLOGY · 11:3 (2005) between proximity to forest boundary and increased risk of crop damage by wildlife (Hill 1997, Naughton-Treves et al. 1998). We observed that most forest patches surrounding the Budongo Forest Reserve are being cleared and turned into agricultural land primarily for sugarcane, thus there are many more farms located at the forest edge now than was the case previously. Though primates, bush pigs and porcupines do, according to farmers, cause significant crop losses locally, farmers considered the extent of the crop damage caused by wildlife to be less than that caused by drought and insect pests (Fig. 6A). The weighted rank index (Fig. 6B) from the farmers’ perspective shows that wildlife is not considered to cause the greatest crop loss in this area. Many other factors contribute to crop loss (e.g. drought, fire, insect pests, plant diseases and poor sowing methods) around the Budongo Forest Reserve. Discussion People’s perceptions of patterns of crop raiding around the Budongo Forest Reserve resembled the results obtained elsewhere (e.g. Newmark et al. 1994, Mubalama 1996, Naughton-Treves et al. 1998, Poole et al. 2002). That 73% of farmers around the Budongo Forest Reserve complain about crop raiding by primates is not surprising since many farms are close to the forest boundary. Forest patches have reduced in size, leading to loss of habitat and resources to primates. However, some species seem to prefer forest-agricultural land boundary areas as demonstrated by Butynski in Bwindi where he recorded higher populations densities of red-tailed monkeys and baboons on the edge of the forest as compared with the interior (Butynski 1984). In addition, farmers living in the neighbourhood of other forests in western Uganda and the Democratic Republic of Congo have reported that primates dominate the assemblage of crop raiders (CARE 1994, Mubalama 1996, Naughton-Treves et al. 1998). It is interesting to note that 93% of the farmers sampled thought that crop raiding has increased over the last 10 years. This shows that primates in particular and other wild animals in general are a growing concern in village farms adjacent to the Budongo Forest Reserve, though this does not necessarily confirm that crop raiding is increasing. As argued in Hill (in press), Naughton-Treves (1997) and Nyerges (1992), various factors such as increasing dependence on agriculture for livelihood, declining alternative employment opportunities, time spent in any location, and influence of past and present conservation and wildlife management strategies can all contribute to people’s declining tolerance of local wildlife. The reported increase in crop raiding incidences from the late 1980s has coincided with the clearing of many forest patches (Marriott 1999, Lauridsen 1999). According to farmers the frequency of crop raiding by primates appears to increase during the months when crops are ready for harvest. Crop raiding was related to seasonal patterns of wet and dry periods. Though severe crop raiding took place in the months when there were plenty of chimpanzee fruits in the forest, the availability of sugarcane in farms throughout the year makes crop raiding a problem to sugarcane growers in the dry season. Similar to other findings (e.g. Reynolds & Reynolds 1965), our results show that during the months of low fruit availability in the forest, chimpanzees feed on many other food items. This is also consistent with other studies which have shown that during periods of food scarcity, animals extend their ranging patterns (Leighton & Leighton 1983) or maintain their usual range areas but... exhibit a dietary shift utilising other foods (Terborgh 1983), and this is true for the chimpanzees of Budongo. Accordingly, chimpanzee movement in and out of the Budongo Forest Reserve may be considered adaptive, and this also may apply to sympatric monkeys. Fluctuation in availability of primate forest foods has also been reported in the nearby forest of Kibale National Park about 300 km south of the Budongo Forest Reserve (Naughton-Treves et al. 1998). Sugar cane must grow for at least 18 months before harvesting, making it a perennial crop and always available, even when all other crops have been harvested. Additionally, sugar cane is a preferred food for chimpanzees (Naughton-Treves et al. 1998), thus the combination of year round availability and being a highly attractive food source for chimpanzees makes sugar cane extremely vulnerable to extensive damage from these animals, resulting in increased conflict between sugar cane growers, forest managers and primate conservationists locally. The conflict arises because farmers have to spend long hours guarding their crops or risk losing them to wildlife. This reduces household time that could be spent on other activities (Hill 1997, 2000). One outcome of crop raiding is when primates, especially baboons, damage very young crops or germinating shoots, and farmers are forced to replant the damaged areas. Farmers indicated that during the planting season, seeds are scarce and some farmers finish all their seed stock at the first sowing. Replanting of damaged fields is thus very costly, as farmers have to buy the seeds from markets or go through the whole period with little hope of harvesting. It is important to note that, though wild animals were not considered the major cause of crop loss to farmers’ harvest, some farmers living close to the forest boundary claim up to 100% losses due to problem animals raiding their crops. This perhaps is, at least in part, a reflection of their heightened perceived risk of crop losses to wildlife. Farmers also lose crops through other causes such as insect pests, drought and plant diseases, which are hard to control given the poor financial positions of many farmers. The only major cause of crop loss for which it is apparently easy to apportion blame is wildlife from the Budongo Forest Reserve. Thus tension between farmers and conservationists is not necessarily because crop raiding animals are the major cause of crop loss, but rather that crops that survive drought, insect pests, poor sowing, plant diseases and fire are also at risk of being damaged at a stage when farmers have high expectations of the coming harvest. As such, crop raiding though not necessarily the single most drastic source of crop loss, confounds other problems. Understanding the patterns of primate crop damage requires careful attention to scale, both spatial and temporal. Given that forests are being fragmented and converted to agriculture throughout East Africa, adaptable primates such as baboons and other Cercopithecine monkeys may become highly destructive to forest edge crops (Kavanagh 1980). Thus the long-term survival of primates is at risk from the low human tolerance for ‘pests’ and the potential impact of eradication of their habitats (Altmann & Muruthi 1988). Given that chimpanzees are an endangered species, understanding patterns of their crop raiding is essential for making informed decisions about their management. Conservation of primates around protected areas like Budongo needs an integrated approach involving the local people because they are directly affected by living alongside wildlife. The significant implication of our findings to the management of Uganda’s forests in particular, and protected areas in general, is that measures targeted at reducing crop raiding due to problem animals are likely to improve a sometimes fragile relationship between farmers, forest managers and conservationists. Acknowledgements - NORAD and NUFU project 63/2003 funded this research through the Faculty of Forestry and Nature Conservation, Makerere University and the Department of Biology and Nature Conservation, Norwegian University of Life Sciences. We are grateful to F. Babweteera of Budongo Forest Project and Prof. V. Reynolds of Oxford University for their help with the study. We thank the two anonymous reviewers for their comments on the manuscript. Prof. J. Swenson, Prof. K.A. Lye, Prof. S.S. Dhillion and Ms Ymke Warren kindly reviewed an earlier draft of the manuscript. We thank Prof. K.A. Lye for the field data collection support as well. We also thank the Budongo Forest Project staff, especially M.G. Mbotella for assisting with data collection. References CARE (Cooperative for Assistance and Relief Everywhere) SPSS INC. 1997: SPSS for Windows releases 8.0. - SPSS Inc. Tweheyo, M. & Obua, J. 2001: Feeding habits of chimpanzees (Pan troglodytes), red-tailed monkeys (Cercopithecus ascanius schmidti), and blue monkeys (Cercopithecus mitis stuhlmannii) on figs in Budongo forest reserve, Uganda. - African Journal of Ecology 39: 133-139.
New Approach of Neural Network for Controlling Locomotion and Reflex of Humanoid Robot Zaier Riadh and Kanda Shinji Fujitsu Laboratories Limited Japan 1. Introduction In recent years, several humanoid robotic platforms have been developed, and most of them were dealing with hardware problems to closely replicate the appearance and the motion ability of human beings. Along with this, motion control also has been advanced, and much work has been focused on the dynamics of the robot using the zero moment point (ZMP) approach (e.g. Vukobratovic & Juricic, 1969; Miura & Shimoyama, 1984; Kajita & Matsumoto, 2001; Huang et al., 2001). Huang et al. proposed a method for planning a walking pattern, where the reference trajectory is designed offline for given constraints on the foot and ground, and satisfying a particular ZMP constraint using third order spline functions. More recently, biologically inspired control strategies have been proposed to generate autonomously adaptable rhythmic movement. These are based on a neuronal network, termed a central pattern generator (CPG) (e.g., Griller, 1985; Taga et al., 1991; Taga, 1995) that is capable of generating a rhythmic pattern of motor activity in the absence of sensory input signals. Taga et al. demonstrated that bipedal locomotion can be realized as a global limit cycle generated through entrainment between a neural network consisting of a neural oscillator and the physical system. On the other hand, toward a safe interaction of the humanoid robot with the environment, Morisawa et al. presented a method to generate an emergency stop motion based on the evaluation on the ZMP and the center of gravity (COG). Okada et al. presented a motion emergency system based on attractor design of the nonlinear dynamical system. Huang et al. proposed a feedback sensory reflex, which consists of ZMP reflex, landing-phase reflex, and a body-posture reflex. However, in the presence of large disturbances, the ZMP will have an arbitrary location that can be out of the stable region in spite of the stability of the robot’s upper body. In this chapter, we deal with both the motion patterns generation and reflexes against sudden events. Instead of using complex modeling and dealing with highly non-linear equations (Okada et al., 2005; Huang & Nakamura, 2005), our control strategy in generating rhythmic motion is simply based on piecewise linear oscillators and a small number of easily tunable parameters. The method needs not to satisfy constraints on robot’s foot or ZMP stability margin as in (Huang et al., 2001). It simply uses piecewise-linear functions. and first order low-pass filters generated by an original recurrent neural network (RNN) (Zaier & Nagashima, 2006), where the “integrate and fire” neuron model (Gerstner, 1995) has been used. The method, therefore, provides much flexibility to the pattern generator so that combination of reflexes during locomotion can be realized without complexity or redesign of the system. To deal with sudden events and large disturbance acting on the robot, most recent works have been approaching this problem by proposing reflex action for each event separately (Huang & Nakamura, 2005; Zaier & Nagashima, 2006). In contrast, our approach consists of presenting the reflex system in a unifying form with regards to four types of sudden events, where we use a simple recognizer based on Bayes rule to detect unexpected events. In this research framework, we 1) add normal feedback signals when a relatively small disturbance is detected by the gyro sensor; 2) change the walk parameters such as the gait, the stride, or the walk posture; 3) add an extra motion at some joints besides the motion generator outputs; 4) stop the walk motion in the case of large disturbance and generate a reflex based on the sensory data and an interpolation of four predefined postures. It should be noticed that the reflexes in 1) and 4) are decided according to the robot’s upper body oscillation rather than the ZMP stability margin (Huang & Nakamura, 2005). Moreover, since the leg during swing phase is made very compliant, there will be neither tipping over when landing nor colliding with an obstacle. In this chapter, we consider more focus on the reflex against sudden obstacle from the stability point of view. Indeed, the behavior of the robot when it encounters an obstacle depends on the timing and location of the collision with regards to the sole plate under the robot leg. In other words, and by considering the state space diagram, the stability of the robot will depend on the distance of the robot state from the equilibrium point and the ability of the robot to return to that point. In this research framework, therefore, the primitive reflex against sudden obstacle that has been proposed in (Zaier & Nagashima, 2006) will be modified by processing the force sensors’ outputs such that the generated reflex movement can smoothly shift the robot state to the attraction domain of the equilibrium point. Experiments using Fujitsu’s humanoid robot HOAP-3 (Murase et al., 2001; Fujitsu Automation Ltd.) demonstrate that the reflex movement is successfully integrated with the rhythmic motion. The robot robustly walks on a number of different ground surfaces and exhibits an efficient natural looking reflex mode. 2. Neural network of rhythmic motion and reflex Shaping an arbitrary motion pattern takes effort to think about the functions that fit the desired task with regards to given constraints. On the other hand, continuous piecewise linear functions have proved to be very powerful tools in modeling and analyzing nonlinear systems. For instance, to fit the real dynamics of the robot, the profile of the rolling motion of a humanoid robot can be approximated using (1). $$e_i \frac{da(t)}{dt} + a(t) = c(t), \quad (1)$$ where \( c(t) \) is the input signal described as a piecewise linear function in time \( t \), \( a(t) \) is the activation function. In fact, for small oscillations the passive behavior fits a sine-wave. But, \[ c(t) = \sum_{i=1}^{N} c_i u_i(t - t_i), \] where \( u_i(t) \in [0,1], t_i \geq 0 \) and \( c_i \) is a real number. Let’s write the equations of the proposed recurrent neural network (Fig.1) that controls the movement of the humanoid robot as follows: \[ \frac{d\theta_i(t)}{dt} = f_i(t, \theta_i) \] \[ f_i(t, \theta_i) = -\frac{1}{\epsilon} \theta_i(t) + g_i(t) \] where the index \( i \) represents either rolling or pitching, \( \theta_i \) is the generated motion to the joints, \( f_i(t, \theta_i) \) is a piecewise continuous function in time \( t \), \( g_i(t) \) is a piecewise function generating the walking as in (2). At the equilibrium points the robot is controlled by the following PD controller, \[ \begin{align*} \frac{dx_i}{dt} &= -a_{ii}x_i + \sum_{j=1, j\neq i}^{N} \frac{a_{ij}}{a_{ii}} x_j + \frac{b_i}{a_{ii}}u_s \\ v(t) &= \sum_{i=1}^{N} c_j x_j(t) \end{align*} \] where \( v(t) \) is the controller’s output to the pitching or rolling joints, \( u_s \) is the sensory input, \( N \) is the order of controller. In this research framework we limit \( N=2 \) as it reduces the controller to two coupled neurons (Zaier & Nagashima, 2006). The parameters \( a_{ii} > 0, a_{ij} \) and \( b_i \) can be easily designed, since optimal values are not required in the proposed design approach. Therefore, the motors’ commands can be expressed as follows; \[ z_i(t) = v(t) + \sigma(\theta_i(t), h_i(t)), \] where \( h_i(t) \) represents the reflex motion, and \( z_i(t) \) is the motor commands. Note that the solution of (3) is \[ \int_{t_0}^{t_1} \frac{d\theta_i}{f_{i0}(t_0)} = \int_{t_0}^{t_1} f_i(s, \theta) ds, \] and since \( g_i(t) \) is a piecewise continuous in \( t \) and satisfies the Lipschitz condition over the interval \([t_0, t_1]\) (time interval during commutation between single support phases), then \( f_i(t, \theta) \) satisfies a local Lipschitz condition over the interval \([t_0, t_1]\) and has a unique solution (Khalil, 1996). ### 3. Generation of walking motion pattern #### 3.1 Stability at the single support phase While the inverted pendulum model considerably simplifies the control of the humanoid robot, the inertia effect of distributed masses such as the arms may present a limitation to that approach. Our method, although inspired by the inverted pendulum, it considers not strictly the system dynamics. In other words, the method can generate a rhythmic movement without solving the nonlinear differential equations of the system dynamics. To illustrate the idea, consider Fig.2, where continuous commutations between single support phases take place. Let’s model the system by a second order ODE with a feedback control input as follows; --- Fig. 2. Commutation of the robot state between equilibrium points defined at the single support phase. \[ \frac{d^2 \alpha}{dt^2} + 2\zeta \frac{d\alpha}{dt} - \mu \alpha = u_g(\alpha), \] (7) where \(a \in R\) is the counter clockwise angle of the inverted pendulum from the vertical, \(\zeta \in R\) is damping ratio, \(\mu=g/l\), and \(u_g \in R\) is the feedback control input stabilizing the system. Let \(\alpha = \theta - \theta_s\), where \(\theta\) is the angular position of the hip joint and \(\theta_s\) is its value when the projection of the centre of mass (COM) is in the support polygon. Then (7) can be rewritten as follows; \[ \frac{d^2 \theta}{dt^2} + 2\zeta \frac{d\theta}{dt} - \mu \theta = u_g(\theta), \] (8) where \(u_g(\theta)\) is the gyro feedback signal stabilizing the inverted pendulum around \(\theta=\theta_s\). Then at each equilibrium point the system has the same eigenvalues as follows; \[ \lambda_{1,2} = -\zeta \pm \sqrt{\zeta^2 + \mu} \] (9) Since \(\zeta<<\mu\), the equilibrium points (9) are saddle ones. Therefore, to generate periodic movement as explained in Fig. 2, we must first stabilize the equilibrium points by a feedback control \(u_g(\theta)=k_1\theta+2k_2d\theta/dt\) using the measured angular velocity of the inverted pendulum. It should be noted that our approach is based on rough model of the robot; there is no need to design optimal feedback gain, however, this gain has to be decided not to cause high vibration of the robot mechanism. ![Diagram](https://www.intechopen.com) 3.2 Rolling motion The rhythmic motion is generated with regards to the rolling profile that is approximated as trapezoidal form, and smoothed using (1). The position command to the hip and ankle is illustrated by Fig.3. The control law at the switching times $t = k\tau$ is expressed as follows; $$\begin{align*} \theta(t^-) &= (-1)^{k+1}\theta_{\max}, \quad d\theta/dt|_{t=t^-} = 0 \\ \theta(t^+) &= (-1)^{k+1}\theta_{\max}, \quad d\theta/dt|_{t=t^+} = (-1)^k \omega \end{align*}$$ (10) where $k$ is the number of half walking cycle $\tau$, the $t^-$ and $t^+$ are the times just before and after commutation, respectively. For $t \neq k\tau$ the state trajectory will follow the desired rolling profile as described in Fig. 3, and the stability of the equilibrium points is guaranteed by the gyro feedback loop added to the system as in (8). Let’s formulate the rolling motion $\theta(t)$ during commutation from $M_0$ to $M_1$ as a function of time delay $\varepsilon$, joint angular velocity $\omega$, walking cycle $T$, and the rolling amplitude $a_s$. $$\theta = f(\varepsilon, \omega, T, a_s),$$ (11) and define the operator $u(.)$ such that $u(t_i, \omega) = \omega_i (t - t_i)$ with $0 \leq u(t_i, \omega) \leq 1$. Using this operator, the periodic rolling motion can be expressed as follows; $$\frac{d\theta(t)}{dt} + \theta(t) = \theta_s \left[ u(t_r0, 2\omega_r) - 2u(t_r0 + (n + f_1)T, \omega_r) + 2u(t_r0 + (n + f_2)T, \omega_r) - u(t_f, 2\omega_r) \right],$$ (12) where $t_0, t_f$ are the switching times for the start and end of the rolling motion, respectively, and $n$ is the number of walking steps. The $f_1$ and $f_2$ are the relative times with regards to the gait. By letting $p = t_{11} - t_{10} - 1/\omega_r$ be the time during which the robot stays at the maximum rolling and $t_{11}$ be the first switching time at the single support phase, we can write $f_1 = (1/\omega_r + p)/T$ and $f_2 = 2f_1 + 1/(\omega_rT)$. Fig. 4. Rolling motion pattern and design parameters. The commands $\theta_{am}^r(t)$ and $\theta_{hm}^r(t)$ will be sent respectively to the hip and ankle joints, which are given by, $$\theta_{am}^r(t) = -\theta_{hm}^r(t) = \theta(t) + \theta_{fb}^r(t),$$ where $\theta_{fb}^r(t)$ is the feedback signal stabilizing (8). Since the position command to the hip is the same as that to the ankle joint with opposed sign, the robot upper body orientation in the absence of disturbance remains unchanged, in other words the angular velocity around the rolling axis during locomotion is zero. Notice that the control law described by (10) is explicit of time. Instead, the state commutation can be constrained by angular velocity $\frac{d\theta}{dt}=0$, and the control law becomes independent of the cycle time as a pure feedback law, however, the commutation time will be no more constant. ### 3.3 Swing motion The dynamic of the swing leg can be considered the same as that of a pendulum, and hence it is inherently stable without any compensator. This motion is generated in a similar fashion as that of the rolling motion, and according to Fig. 4 it is expressed by the following equation: $$\varepsilon \frac{d\theta_l(t)}{dt} + \theta_l(t) = a_l[u(t_{l0} + nT, \omega_l) - u(t_{l1} + nT, \omega_l) + u(t_{l2} + nT, \omega_l) - u(t_{lf} + nT, \omega_l)],$$ (14) where $\theta_l$ is the lifting motion and $a_l$ is its amplitude. The $t_{l0}$ and $t_{l2}$ are the switching times of lifting for the first and second half walking cycle, $t_{l1}$ and $t_{lf}$ are the switching times of landing for the first and the last half cycle, and $\omega_l$ is the joints’ angular velocity. It should be noticed that the proposed motion pattern generator generates dynamic walking motion as shown in Fig. 3, where the lifting time $t_{l0}$ in Fig. 4 is very close to the rolling time $t_{r0}$. Similarly, the angular position $\theta_s$ generating the stride is expressed by the following equation; $$\varepsilon \frac{d\theta_s(t)}{dt} + \theta_s(t) = a_s[u(t_{s1} + nT, \omega_s) - u(t_{s2} + nT, \omega_s)],$$ (15) where $a_s$ is the amplitude of the angular position generating the stride. The $\omega_s$ is the joints’ angular velocity. The $t_{s1}$ and $t_{s2}$ are the times at the start and the end of stride, respectively. On the other hand, we assume that the landing of each leg is accomplished with a flat foot on a flat ground, and the thigh and shank of the robot have the same length. Therefore, with respect to the angles defined by (Fujitsu Automation Ltd.), this condition can be satisfied as follows. \[ \begin{align*} \theta^a_p(t) &= \theta_l(t) + \theta^f_{fb}(t) + \theta_s(t) \\ \theta^k_m(t) &= -2\theta_l(t) \\ \theta^h_m(t) &= \theta_l(t) + \theta^f_{fb}(t) - \theta_s(t) \end{align*} \] where \(\theta^a_p\), \(\theta^k_m\), and \(\theta^h_m\) are the pitching motor commands to the ankle, the knee and the hip, respectively. The \(\theta^f_{fb}(t)\) is the feedback signal to the ankle and the hip, satisfying the stability of inverted pendulum in the sagittal plane as in (7). Moreover, to minimize the force of the collision of the landing leg with the ground, instead of using impact model, besides (17), we control the damping factor \(b_s\) and the spring stiffness \(k_s\) of the virtual damper-spring system (19) such that the leg is very compliant at the swing phase, and gradually get stiffer till it reaches the maximum stiffness at the single support phase. \[ m \frac{d^2 y_c(t)}{dt^2} + b_s \frac{dy_c(t)}{dt} + k_s y_c(t) = F_y, \] where \(y_c(t)\) is the displacement of the mass \(m\) along the vertical axis, and \(F_y\) is the external force acting on the supporting leg. The angular positions to the motors’ commands becomes \[ \begin{align*} \theta^a_p(t) &= \theta_l(t) + \theta_s(t) + \theta^f_{fb}(t) + \theta_c(t) \\ \theta^k_o(t) &= -2\theta_l(t) \\ \theta^h_m(t) &= \theta_l(t) - \theta_s(t) + \theta^f_{fb}(t) + \theta_c(t) \end{align*} \] where \(\theta_c(t) = \arcsin(y_c(t)/L)\) is the angular position induced by the virtual damper spring system in (17), and \(L\) is the length of the thigh. 4. Reflex system In order to prevent the falling down of a humanoid robot when it suffers a sudden deviation from its stable state, we have proposed a reflex system that can be triggered by sensory signals. In the previous result (Zaier & Nagashima, 2006), we studied three cases of sudden events; (1) when there is a sudden change in the ground level, (2) when the robot is pushed from arbitrary direction, and (3) when there is a sudden change in load. 4.1 Reflex against large disturbance For the case of large disturbance, we defined a normalized angular velocity at the x-y plane termed gyro index "\(g_i\)”, and it is given by, New Approach of Neural Network for Controlling Locomotion and Reflex of Humanoid Robot Fig. 5. Gyro index and rolling joint’s output during walking when no large disturbance is present Fig. 6. Sole reaction forces acting on the sole plate and desired ZMP. \[ g_i = \sqrt{\mu^2 \text{gyro}_x^2 + \text{gyro}_y^2}, \] (19) where gyro\(_x\) and gyro\(_y\) are the components of the gyro sensor’s output along the rolling and pitching axis, respectively. The parameter \( \mu = L/w \) is the size ratio of the sole plate, where \( L \) and \( w \) are the length and the width of the robot sole plate, respectively. The decision about the presence of large disturbance is based on a threshold \( T_{gi} \) which we obtained experimentally by disturbing the robot to the level beyond which stability by PD controllers will not possible. Fig. 5 shows the experimental result of the Gyro index in the absence of large disturbance. Moreover, we defined four postures around the walking motion which we called learned postures. When a large perturbation occurs such that the threshold \( T_{gi} \) is touched, the robot will stop walking and shifts its pose to one of learned postures selected according to the measured ZMP position. A gyro feedback controller will be activated stabilizing the final pose the humanoid robot has shifted to. In order to find the ZMP during locomotion, we simply use the sole reaction forces defined in Fig. 6, which is calculated using the force sensors’ values as follows, \[ x_m = \left[ x_1(F_1^1 + F_3^1 - F_2^1 - F_4^1) + x_2(F_2^1 + F_1^1 - F_3^1 - F_4^1) \right] / F_r \] (20) \[ y_m = \frac{y_1(F_T^r + F_T^l + F_3^r + F_3^l) + y_2(F_T^r + F_T^l + F_2^r + F_2^l)}{F_T}, \] (21) where \(F_T\) is the sum of all forces acting on the legs. Notice that the stride effect on \(y_m\) is neglected since the duration of the double support phase is almost zero and is much smaller. Fig. 7. Sole plate of the robot; the curve in red is the ZMP trajectory during the single support phase. The (a, b, c, and d) are the zones to which the ZMP will shift when disturbances occur. Fig. 8 Defined zones (a, b, c, and d) under the sole plate and reflex actions that take place when the large disturbance occurs. The reflex consists of switching the pose of the robot to the appropriate predefined posture according to the ZMP position. Notice that when the robot is pushed from the right-front, the ZMP position is between zone (b) and zone (d) shown in Fig 7, and consequently the left leg is stepped back to the left side. than the time delay of the ZMP controller. The ZMP during walking and in the absence of large disturbance can be described by the curve in Fig.7. To generate a reflex motion when large disturbance acts on the robot’s upper body, we define four zones under the sole plate and for each zone we define a posture such that when the ZMP is shifted to one zone in the presence of large disturbance, the robot will stop walking and modifies its pose to the appropriate posture, as described in Fig. 8. If the ZMP shifts between two of these four zones, linear interpolation will be considered between the two corresponding defined postures. Notice that a large disturbance is detected when the gyro index (19) touches the Robot is walking Record the ZMP during single support phase Check the gyro data If $g_i < T_{gi}$ Continue Walking Stop the motion Find the position to which the ZMP shifted, Fig. (6) Find posture or interpolate and switch the robot to it Activate controllers at the final posture Fig. 9. Flowchart of reflex activation when a large disturbance is present Fig. 10. Detailed results in the presence of large disturbance; (A) shows the gyro index that touches the threshold at 5.4 s. (B) shows the ZMP positions during walking defined within the support polygon, where $x_m$ is varying between the right and left legs, while $y_m$ is defined along the sole plate from 0 to 10 cm. At 5.4 s the large disturbance was detected and the ZMP has shifted to the circled points, which correspond to $x_m = 2.0 \text{cm}$ and $y_m = 8.4 \text{cm}$. Finally, (C) shows the pitching and rolling joints’ outputs of the left leg. Fig. 11. HOAP-3 walking and encountering a sudden change in ground level threshold $T_g$. The steps from the detection of large disturbance till the activation of a reflex motion are described by the flowchart in Fig. 9. The experimental results of the case when the robot is pushed from the back are detailed in Fig. 10. ### 4.2 Reflex against sudden change in ground level Other type of sudden event we studied is the reflex against sudden change in ground level (Fig. 11) that is detected using a photo-interrupter attached to the front of the robot foot. The reflex movement will be triggered when the photo-interrupter, at the landing time of the leg, dose not detect a ground. The reflex movement consists of increasing the stride so that the foot collides not with the upper ground. Afterwards, the supporting leg will be contracted in height till the swing leg touches the lower surface. After landing, the walk parameters (gait and stride) will be set to their previous values. Notice that our proposed reflex needs not to know about the ground elevation. This parameter is detected automatically by the sole sensor, where we assume that the change in the ground level is within the hardware limit of the robot. The joints’ outputs are shown in Fig. 12. The extra motion (d) is added to the supporting leg joints contracting the leg at height. The contraction is stopped when the swing leg touches the lower surface. The contraction phase of the supporting leg starts when the linear velocity of the upper body is almost zero. Moreover, the contraction speed is low enough to ensure that the contracting leg will not affect the stability of the robot. The walking cycle time is augmented by about 50% at the sudden change in ground level. The motion of the supporting leg is modified accordingly. Humanoid Robots 4.3 Reflex against sudden obstacle This type of reflex is activated when a sudden obstacle touches the sole sensor of the leg at the swing phase. We assume here that the foot of the leg remains parallel to the ground during the swing motion, which is satisfied by (16). The reflex process is abstracted as follows: - Detect the sudden obstacle with a sole sensor. - Stop the motion of the robot. - Move the state of the robot to the attraction domain of the stable equilibrium point. - Resume the walking motion with negative stride, then follow upper level control. Let’s write the equations of the reflex motion as follows, \[ \varepsilon_p \frac{dh_p(t)}{dt} + h_p(t) = u(t-t_{sw})(a_l - \theta_{swp}) \] \[ \varepsilon_r \frac{dh_r(t)}{dt} + h_r(t) = u(t-t_{sw})(\theta_s - \theta_{swr}) \] where \( u(t) \) is a unit step function starting at \( t \). The \( h_c(t) \) is the angle to the pitching joints of the leg touching the obstacle, which will be added as \( \theta_c \) in (16), and \( h_p(t) \) is the angle to the rolling joints of the ankles and hip of both legs. The \( \varepsilon_r \) and \( \varepsilon_p \) are neurons’ time delays with much smaller values than \( \varepsilon \) in (4), \( \theta_{swr} \) and \( \theta_{swp} \) are the rolling and pitching values, respectively, at the time \( t_{sw} \) when the sudden obstacle is detected, \( a_l \) is defined in (14), and \( \theta_s \) is the rolling amplitude. Fig. 13 shows HOAP-3 detects a sudden obstacle as it walks. The joints’ outputs are shown in Fig. 14. At 3.0 s, the sole sensor of the left leg touches the obstacle and the robot stops landing its leg and increases its rolling motion while keeping the gyro feedback controller active. The robot, then, retracts the left leg to its previous landing position. This is shown in Fig. 14 by the pitching motion of the hip, knee, and ankle within the time interval [3.0s, 4.8s]. The walking is resumed successfully at 6.8 s. Notice that the leg during swing motion is made very compliant, where the stiffness is controlled during the gait such that the leg at the middle of the supporting phase is very stiff, while it is very compliant during the swing phase. 4.4 Reflex against sudden change in load We consider the reflex when the humanoid robot detects a sudden change in load as it walks, which is considered as a large disturbance but to the level that the ZMP remains ![Fig. 13. Reflex against a sudden obstacle while walking.](www.intechopen.com) inside the support polygon. The proposed reflex policy is shown in Figs. 15 and Fig. 16. The reflex motions \( \theta_w \) and \( \theta_a \) will be generated simultaneously at the ankles and waist joints, respectively (Fig. 15 c). The amplitudes of these angles are set according to the deviation angle of the upper body. During this phase only, the gain of the gyro feedback controller, which works against oscillation of the robot’s upper body, is reduced by more than half. After this phase, the gain of the gyro feedback controller is set to its previous value (Fig 15 d). Fig. 17 shows HOAP-3 carrying a relatively heavy box. As it walked, the box was taken away and the robot could walk stably and compensate for the change by adjusting its walking posture at the ankle and waist joints according to the algorithm in Fig. 16. The positions of the ankles and their change during walking are shown in Fig. 18. The reflex motion is generated within the time interval [6.0s, 7.0s]. It should be noticed here that the reflex is triggered by the gyro sensor when its value exceed a given threshold, while the reflex motion is selected according to the recorded ZMP at the disturbance detection time. ![Diagram](image-url) Fig. 14. Joints outputs when reflex against sudden obstacle is activated ![Diagram](image-url) Fig. 15. Proposed control policy at a sudden change in load; (a) The robot is carrying a box, (b) The box is fallen down, (c) generation of reflex motion in the waist and ankle joints, (d) ZMP and Gyro feedback control. Humanoid Robots Reduce gyro controller gain & Generate ankle and waist motion $\theta_w, \theta_a$ (Fig. 15 c) Set gyro controller gain to the previous one (Fig. 15 d) Continue walking or stop Fig. 16. Flowchart of reflex at sudden change in load. Fig. 17. Reflex against sudden change in load while walking Fig. 18. Joints outputs at the sudden change in load. As shown in Fig. 16, $\theta_w$ and $\theta_a$ are the angles added to the ankle and waist joints, respectively. $u_{zmp}$ and $v_{zmp}$ are the ZMP feedback controls to the ankles and waist joints. 4.5 Unified reflex system To deal simultaneously with several types of undesired events, the reflex system has to be designed with a structure that can be extended to cover, to some extent (e.g., hardware), several types of sudden events that may act on the robot. If we consider that prior knowledge about the type of sudden event is provided, and by defining a discriminant function $d_i(s)$ based on the Bayes rule, the general structure of the recognizer can be represented as shown in Fig. 19. In this research frame work, the recognizer is limited to four types of sudden events that we studied in the previous subsection. To build up the recognizer, sensory data and motion related parameters are collected. When extracting the appropriate features required for each type of sudden event, we realized that the recognizer can be simplified into two dichotomizers (Fig. 20). The first dichotomizer consists of reflex actions against large disturbances. That is, when an input from the gyro sensor $s_1$ exceeds a given threshold, discriminant functions $d_1$ and $d_2$ will use that feature but the decision will depend on input’s feature $s_2$. For instance, when the ZMP remains inside the support polygon, the disturbance is considered to be of type one. If the ZMP leaves the support polygon, then a disturbance will be of type two. For example, pushing a robot as it is walking can be classified as a large disturbance of type one if the ZMP remains inside the supporting polygon, otherwise, it is of type two. As for the second dichotomizer, $d_3(s)$ activates the reflex action against a sudden change in ground level when the photointerrupter that is attached to the front of the leg is enabled at landing time, while $d_4(s)$ activates the reflex against a sudden obstacle when the sole sensor of the swing leg touches an obstacle. Fig. 21 shows the overall scheme of the reflex system and motion pattern generator. 4.6 Adaptive reflex system In the previous subsection, although the reflex was proposed in a unified fashion with respect to four types of sudden events, adaptation of the reflex was not considered. For instance, the reflex against sudden obstacle, in some situation, may fail to prevent the falling ![Diagram](image_url) Fig. 19. General structure of the unexpected pattern recognizer, where $s_i$ represents the normalized input signal and $d_i(s)$ is the discriminant function. Fig. 20. Structure of the unexpected pattern recognizer after features extraction. Fig. 21. Overall scheme of the reflex system and motion pattern generator; $\sigma(t)$ is the sum of reflex $h(t)$ and the motion pattern generator output $\theta(t)$ Fig. 22. Overall scheme of the adaptive reflex system and motion pattern generator Fig. 23. The state of the robot depends on the relative position of the sudden obstacle with regards to the sole plate. Notice that the commutation of the state between equilibrium points is realised by gravity of the robot. In this section, therefore, we propose a new adaptation algorithm as shown in Fig. 22, which will adapt the reflex motion and the recogniser as well. In this research framework we limit the adaptation to the reflex against sudden obstacle. Let consider our previously proposed reflex (22) and (23) as a primitive one, and abstracted as follows: - Detect the sudden obstacle with a sole sensor. - Stop the motion of the robot. - Move the state of the robot to the attraction domain of the previous equilibrium point. However, if the obstacle does not provide a stable supporting surface, it will be hard for the robot to step forward and stand up stably on the obstacle. For instance, when an obstacle touches the obstacle in the half sole plate adjacent with the other leg, the robot state will not be able to return to the equilibrium point defined by the other leg. Due to the dynamic walking pattern (i.e., the commutation of the ZMP from one leg to the other is realized by a free fall of the humanoid robot) and the presence of time delay in triggering the reflex, the ZMP may become out of the support polygon formed by the leg’s sole plate and the obstacle (Fig. 23a), which make the primitive reflex unable to prevent the falling down of the robot. To face such a problem there are two solutions; either to increase the support polygon area or to change the robot posture so that the ZMP becomes inside the stability zone. Intuitively, it is easier to consider the first possibility rather than the second one, by rolling or pitching the ankle joint of the leg touching the obstacle. Moreover, using Fig. 24. The stability zone $D$ is coloured in gray; it corresponds to the zone from which the landing and rolling to the other leg start Humanoid Robots 384 If the center of pressure is inside the stable zone Y Pitch the ankle joint using (21) Rolling using (13) ZMP under the sole plate of other leg N Pitching (16) When landing, the ankle is compliant such that it can adapt to the ground To resume walking is there any new path N Y Generate new path Dynamics calculation, it is possible to show that this reflex corresponds to the minimum energy the robot may spend to achieve stability. In some cases, however, environmental constraints may impose the second solution to be adopted, for instance, by lowering the COM, or even by relying on a fixed object nearby the robot. These intuitive actions can be considered as hints to adapt the neural network with additional reflexes covering cases similar to that of Fig.23a, which depend on the relative position of the obstacle with respect to sole plate and the environment surrounding the robot as well. Therefore, the augmented reflex is proposed as follows; \[ \begin{align*} \varepsilon_r \frac{ds_a}{dt} + s_a &= s_a(t)u(t_{obs}) + k(u(t_{obs}) - u(t_{cont})) \\ \frac{dx_i}{dt} &= -a_{ii}x_i + \sum_{j=1}^{N} a_{ij} x_j + \sum_{j=1}^{N} \frac{b_j}{a_{ii}} e_j(t) \\ r_a(t) &= s_a(t) + \sum_{i=1}^{N} c_i x_i \end{align*} \] (24) 1.0 s 0.86 s 0.46 s 0.13 s 0 s Fig. 26. Primitive reflex against a sudden obstacle while walking; the ZMP is outside the support polygon formed by the right leg and the obstacle. Fig. 25. Flowchart of the improved reflex against sudden obstacle, where the reflex is triggered when the sole plate touches the obstacle at the swing phase. where \( u(t_i) \) is as defined in (22), \( \varepsilon_r > 0, \varepsilon_i \) is the distance of the ZMP from the center of the sole plate, \( k \) is the integration constant, \( r_d(t) \) is the reflex motion to the ankle pitching joint. \( s_0(t) \) is an integrated angular position from the time when the obstacle is detected \((t_{\text{obs}})\) till the time when the sole plate touches the ground making a stable support polygon \((t_{\text{cont}})\). The \( a_i > 0, a_j \) and \( b_i \) are parameters of the PD controller defined as in (5). The stability zone \( D \) is described in Fig. 24, which depends on the walking stride and is defined by the timing when the leg touches the ground (for dynamic walking the rolling at this timing is zero). Fig. 25 shows the proposed adaptive reflex algorithm. Notice that the whole control diagram is shown in Fig. 22, where the adaptation part consists of (24) and some check regarding the stability domain \( D \) at the collision time. The first step consists of finding the center of pressure (or position of the obstacle). Then, if this position belongs to the stability zone \( D \), the leg will expands in length by inverting the sign of sensor feedback output in (16) so that the state of the robot reaches the attraction domain of the equilibrium point under the supporting leg. Otherwise, the reflex (24) will be generated, which consists of augmenting the support polygon by pitching the ankle joint. Once the robot reaches the stable state it follows upper level commands, either by walking over the obstacle or stepping back and finding a new path. In the case of walking over the obstacle, the locomotion controller will generate a static walking: this is by shifting the time \( t_{\text{lo}} \) from \( t_{\text{root}} \) (Fig. 4), so that the lifting starts only when the projection of COM is under the other leg. This walking style is also adopted by human whenever he walks on rough or unstable terrain. **Remark**: The advantage of (24) over the pitching expression (22) is that only the ankle of the leg that collides with the obstacle is pitched by an angle such that the support polygon covers the ZMP at the collision time. Moreover, although we used a ZMP feedback loop besides (22), the response is not fast enough to prevent the falling down of the robot. To show the effectiveness of our newly developed adaptive reflex we conducted two experiments. Fig. 26 shows the experiment results when HOAP-3 detects a sudden obstacle as it walks, using the primitive reflex. Since the collision position of obstacle with the sole plate is out of the stability zone \( D \) (Fig. 24), the robot was not able to get stable by the primitive reflex (22) and (23), and therefore it has fallen down. Fig. 27 shows the case when the proposed reflex was implemented, where the joints’ outputs are shown in Fig. 28. ![Fig. 27. Adaptive reflex against sudden obstacle under similar conditions of that in Fig. 10; the ankle of the left leg is pitched at the detection time of the obstacle, then it is controlled](www.intechopen.com) such that the center of pressure is in the middle of the sole plate. At the same time the leg is extended so that the state of the robot reaches the equilibrium point under the right leg. ![Diagram of humanoid robot showing reflex trigger, rolling motion, and ankle motion](image1) **Fig. 28.** Ankle joints’ outputs when the proposed reflex against sudden obstacle is activated At 3.14 s, the sole sensor of the left leg touches the obstacle and the pitching joint of the ankle was controlled according to (24) by $s_a(t)$ (fast response), then by $r_a(t)$ at 3.27 s, which is delayed by $1/a_{ii}$. Fig. 29 shows the ZMP position, where the location of obstacle is as described in Fig. 23a. The state of the robot reached the equilibrium point at about 4.0s, where the rolling joints get the static value (the projection of COM is under the right leg). Notice that the mode to resume motion by walking on obstacle is still under research. ![Diagram of ZMP position](image2) **Fig. 29.** ZMP position when reflex against sudden obstacle is activated 5. Conclusion The reflex system was combined with the motion pattern generator to improve the robustness against lateral and frontal disturbances. On the other hand, the reflexes that highly adapt and control the movement of the humanoid in the presence of large disturbance acting on the robot’s upper body were considered in a unified form. It was shown that a reflex movement was successfully enabled and integrated with the rhythmic motion in the cases of a sudden change in the floor level and a sudden obstacle, and in the presence of a large disturbance. Moreover, the proposed reflex against sudden obstacle was further investigated, and it was shown that when obstacle collides with the sole plate of the robot leg in a location out of a defined stable domain, the robot could not reach stability and fall down. On the other hand, an adaptive reflex was proposed that consisted of increasing the support polygon by controlling the ankle joint of the leg touching the obstacle. In order to demonstrate the effectiveness of the proposed system, we used the humanoid robot HOAP-3 of Fujitsu. It was shown that a reflex movement was successfully enabled and integrated with the rhythmic motion. As a future work, we will extend the reflex system by considering the interaction between the upper and lower body of the humanoid robots. 6. References Humanoid robots are developed to use the infrastructures designed for humans, to ease the interactions with humans, and to help the integrations into human societies. The developments of humanoid robots proceed from building individual robots to establishing societies of robots working alongside with humans. This book addresses the problems of constructing a humanoid body and mind from generating walk patterns and balance maintenance to encoding and specifying humanoid motions and the control of eye and head movements for focusing attention on moving objects. It provides methods for learning motor skills and for language acquisition and describes how to generate facial movements for expressing various emotions and provides methods for decision making and planning. This book discusses the leading researches and challenges in building humanoid robots in order to prepare for the near future when human societies will be advanced by using humanoid robots. How to reference In order to correctly reference this scholarly work, feel free to copy and paste the following:
Is it reasonable to require any person or organisation to purchase specific software in order to be able to communicate with a governmental organisation? This question is at the heart of an ongoing debate in many countries within the EU, because of its implications for accessibility, transparency, democracy, and fairness in procurement and markets. In this paper we consider the inability of many Swedish governmental organisations to communicate in open formats, and report on an investigation into policy formulation which has led to this situation in one sector - local government. We conducted a survey of all municipalities in Sweden. The final response rate was 99%, after 4 months and a maximum of 7 reminders. We find that there is little or no evidence of consideration given to document formats when procuring software. And in a large majority of cases, there is no documentation of any decision process. Further, organisational adoption of application suites seems more influenced by tradition and a desire to upgrade existing IT infrastructure than by any form of analysis and evaluation prior to purchase. In several municipalities specific applications are even named in procurements, which is in conflict with EU directives. There is also considerable confusion amongst respondents related to the difference between application and file format. We make a number of recommendations. Evaluation of document formats should always precede decisions on application and should include interoperability and lock-in considerations. Municipalities must take responsibility for the evaluation of both document formats and office applications before adoption. Further, when assessing the total cost of ownership the analysis should include consideration of exit costs in the procurement. The study highlights a lack of strategic decision making with respect to accessibility, and a resultant lack of transparency with respect to ICT procurement. 1. Introduction In a public speech in Brussels, Neelie Kroes, then European Commissioner for Competition Policy, stated that “No citizen or company should be forced or encouraged to use a particular company’s technology to access government information.” (Kroes, 2008) In a strange twist to this statement, a report commissioned by the Swedish government (SOU, 2010) on access to public information states that: “It is not reasonable to require an authority to purchase new software to be able to provide information in electronic form.” Does this represent a stand-off between the rights of an individual and the rights of government organisations? Or does it represent a natural tension which needs to be resolved technically? A clue is contained in the same report: “Even if an agency discloses a public document in electronic form, it is irrelevant to the individual if that disclosure is made in such a way that he or she cannot access that information in readable form.” (SOU, 2010) To resolve this tension, then, there is a need to separate out the issue of software purchase - with the reasonable concern about public authorities having to maintain many systems to allow provision of documents in any requested format - from the issue of accessibility of document content. In interoperability terms, this reduces to a need for agreed standard formats, which can be supported by many software products provided on many platforms. This chimes with the recommendation from the Swedish archiving association TAM-Arkiv (TAM, 2010) for long-term access to documents, namely: “Never use vendor dependent formats for long term storage if you can avoid it, because they often are too unstable, too unstructured, and with dependencies to different suppliers’ business strategies.” (stress as in the original) The recommendation stresses the difficulty of assessing how long proprietary formats will be supported, and thereby finds them unsuitable for long-term storage. In fact, for decades organisations in the public sector have been concerned about the need for “avoiding vendor lock-in when procuring IT infrastructure.” (Guijarro, 2007, p. 91) With growing recognition of the problems associated with reliance on proprietary formats, there is a commensurate growth in calls for the use of open standard formats for document interchange. An important principle underlying the idea of an open standard is that it ensures that data can be interpreted independently of the tool which generated it. This is one of the main reasons behind the recommendations of the FLOSSPOLS (2005) project that: “open standards should be mandatory for eGovernment services and preferred for all other procurement of software and software services.” In line with this, we note that policies on using open document formats in the public sector have been adopted in a number of European countries, including two of Sweden’s neighbouring countries: Denmark (Denmark, 2010; ITST, 2010) and Norway (Regjeringen, 2009a; Regjeringen, 2009b). With the adoption of such policies it is clear that there are European countries that expect software companies to adopt open standards “if they want their products to be used by the government.” (Fairchild and de Vuyst, 2007, p. 150) One major justification for this is clear: when people want to “interact with government, in either their role as a citizen or a member of a business, they want to do so on their own terms.” (Borras, 2004, p. 75) Over the years, public sector organisations have used a range of different open and proprietary document formats. ODF (ISO/IEC 26300:2006) and PDF/A (ISO 19005-1:2005) are two open standard formats, which have been recognised as international standards (by ISO) and as national standards in many countries. Both formats have been adopted and implemented by different providers of software systems. Two examples of proprietary file formats are IBM’s RFT-format and Microsoft’s doc-format. Open standards have been discussed by researchers and policy makers for a long time (e.g. Bird, 1998; EU, 2004; SOU, 2009). An open standard (EU, 2004; SOU, 2009) is a standard which has certain open properties. Such standards can be used as a basis for implementation in software systems under different (proprietary and open source) software licenses. A standard is “a published document that contains a technical specification or other precise criteria designed to be used consistently as a rule, guideline, or definition.” (BSI, 2010) When a standard is published and its technical specification contains sufficiently detailed information it can be used as a basis for implementation in software applications. For example, the ODF document format has been implemented by several providers using different (proprietary and open source) software licenses (e.g. OpenDoc Society, 2011). On the other hand, the specification of the published Office Open XML standard (ISO/IEC 29500:2008) contains references to external web pages (referring to one specific company’s own web site) which are not available. We note that these formats and standards have been extensively discussed (e.g. Brown, 2010; MacCarty and Updegrowe, 2009; Tsilas, 2008), but acknowledge that an analysis of this discussion is beyond the scope of this paper. From a legal perspective, Swedish and European law for public procurement aims to achieve procurement practices that stimulate a fair and competitive market based on the important principles of transparency, non-discrimination and equal treatment (Directives 2004/17/EC and 2004/18/EC). These directives clarify the public procurement process and how technical specifications can and shall be used in such processes. An important basis is that technical specifications “shall afford equal access for tenderers and not have the effect of creating unjustified obstacles to the opening up of public procurement to competition”. Further, a technical specification “shall not refer to a specific make or source, or to a particular process, or to trade marks, patents, types or a specific origin or production with the effect of favouring or eliminating certain undertakings or certain products.” (Directive 2004/17/EC (Article 34) and Directive 2004/18/EC (Article 23)). Only on an “exceptional basis” (e.g. when functional requirements cannot be described and for a subject-matter for which there is no international standard) public procurement may refer to specific trade marks and products, but procurement of document formats and office applications is not such an exception. In this paper, we first consider the recorded situation with respect to support for open document formats in Swedish governmental organisations. We then report on a new study of policies on document formats and ICT procurement related to office document processing. The objective is to understand the influences behind established practice in decision making in Swedish municipalities, and hence help to explain earlier findings of a lack of engagement with the issue of document formats. 2. Background An earlier study investigated the level to which Swedish local authorities, health regions and governmental organisations were unable or unwilling to process an ODF file sent to them (Lundell and Lings, 2009). ODF was chosen as an exemplar of an open document format which some European governments insist on being supported by their organisations. Less than a quarter of local authorities responded to the ODF questionnaire; more than two thirds of respondents acknowledged that they were unable or unwilling to open the document sent to them in ODF. More than a third listed no open formats as preferred for receiving documents. However, a large majority endorsed proprietary formats for such communication. A part of the investigation was into policies related to the document formats which were accepted. It was found that an understanding of document formats as separate from products using those formats was very low, and there was a surprising and worrying lack of associated policies and strategies available. Only 4 percent claimed to have a policy on accepted document formats, and of these the majority simply endorsed a proprietary format. Policy making was found not to be transparent, with practice left to the influences of managers and technicians. There is also an evident gap between what public organisations have stated publicly about receiving documents in open formats and what those same organisations do in practice. There were authorities which claimed to accept communications in ODF, but were amongst those failing to open the ODF document sent. The majority which did open the ODF document responded to the questions in a proprietary format. A second investigation looked at practice in local government with respect to electronic records of important board minutes (Lundell and Lings, 2010). These are not legally required to be archived in electronic form; the only legal requirement is for each municipality to maintain paper copy of the minutes of that board. It was therefore considered to be a good indicator of practice in the absence of a legal requirement. In the study, minutes were requested, in their electronic form, for the executive boards. It was emphasised that the documents should be supplied in their stored format. The following minutes were requested from each: the most recent board meeting; a meeting from ten years ago; the oldest stored electronically. This gave a perspective on availability and the document formats used. It was found that there are already significant gaps in the electronic archives. No municipality was found to have a policy with respect to maintaining electronic copy of executive minutes. In the absence of a direct duty to preserve electronic copy, paper copy is still overwhelmingly seen as the only archive medium. This is in spite of the fact that Sweden is considered amongst the most advanced countries in e-Government. Where electronic copy is kept, it was found that proprietary and closed formats are overwhelmingly used for public documents. This was the case even though there was experience of losing access to documents because of formats which were no longer supported. Further, there was no evidence that the situation was changing. No municipality provided a document in a reusable, open standard document format, in stark contrast with stated central Government vision. In fact, in its 2004 IT bill (2004/05, 175), the Swedish government declared that the use of open standards should be promoted (Regeringen 2005; EU 2005). We also note that the responsible minister for Swedish municipalities has expressed support for open standards as defined in European Interoperability Framework version 1.0 (Odell, 2009), which has also been adopted in the Swedish e-Government strategy (SOU, 2009). Further, based on a legal analysis by the Swedish Association of Local Authorities and Health Regions, there is a recommendation that citizens should be allowed to communicate with members using the established open standard ODF (Lundell and Lings, 2009; SALAR, 2007; SALAR, 2008). 3. Research Method The research question addressed through this study is the following. Given that certain document formats are preferred by municipalities in Sweden, to what extent are these preferences informed by policies, either related to document formats or to software procurement? The question is made easier to answer in Sweden, which has a very strict policy on governmental responses to questions: all questions must be responded to. We sent an email in plain text to each municipality (290 in all), with follow-up reminders sent over a three month period. The email contained six requests. In the first section, the municipalities were asked about document formats, specifically the format actually used by each municipality in their earlier communication with us. The first was a request to supply any policy or strategy document related to sending out documents in the specified format. The second was a request to inform us of any organisational decision behind the use of the specified format, and to supply any documentation. The third asked for information about any planned revisions to working practice. The second section related to software procurement, and in particular that related to software for writing office documents. The first two requests were for factual information about the application primarily recommended within the municipality: what is it and when was it (or an earlier version of it) first introduced into the organisation? The third was a request for the documented decision (along with any other related documents) for the most recent procurement related to the application. The study resulted in both quantitative and qualitative data. Quantitative data was analysed to gauge the overall position with respect to informed decision making about document formats and office applications. The text of responses, together with that of any supplied documents, was analysed qualitatively, to give some insight into the real state of practice. 4. Responsiveness to the questionnaire The request email was sent to the registered address of each municipality. A municipality is required to respond promptly (at least with an acknowledgement), usually interpreted to mean within 24 hours. If no response was received within a working week, then a reminder was sent. This continued with, after the second reminder, increased emphasis that the email included a request for public documents that they are required by law to respond to. This resulted in the response profile shown in Figure 1. As can be seen, 20% (59) of the municipalities responded to the initial request within 3 working days. A reminder elicited further responses, resulting in a 42% response rate (122) after 3 weeks. After a second reminder, the majority (59%) had responded. The final response rate after 4 months was 99%. Overall, a maximum of 7 reminders was used, although many further interactions were required to probe more deeply when initial responses were inadequate. Four municipalities failed to respond. Some delays were evidently caused by confusion over who should respond, no individual feeling able to respond to all requests. This meant that the email was circulated within the organisation. In some cases this resulted in partial answers being given from different parts of an organisation - primarily a split between answers to the two sections of requests. The second section was often answered by the ICT department. This even resulted in different responses being made to the same request by different people within the same organisation. In a small number, one ICT department served several municipalities. This caused initial confusion over whether an individual response had been made on behalf of more than one municipality. A few municipalities explicitly declined to respond and some provided partial responses, which were probed further. It is possible that some people interpreted the email as a survey and missed the fact that it contained explicit requests for public documents. A few spent time on a response refuting their obligation to respond. In these cases, a simpler request for the required documents was sent (with reminders) which did elicit some responses. We estimate that, for a well organised authority, it should take less than ten minutes to respond to the email (we have anecdotal information which reinforces this), so it is unlikely that resource demand was a significant factor in a decision not to respond, or in an extreme delay in responding. 5. Observations from the analysis Few municipalities have a documented policy regarding the use of document formats (see Table 1). <table> <thead> <tr> <th>Documented policy for document format exists?</th> <th>Percentage of municipalities</th> </tr> </thead> <tbody> <tr> <td>Responded yes</td> <td>2%</td> </tr> <tr> <td>Responded no</td> <td>95%</td> </tr> <tr> <td>Decline to respond</td> <td>3%</td> </tr> </tbody> </table> Only 2% of all (290) Swedish municipalities claimed to have a documented policy for the practice of sending out documents in the specific formats used by their municipality. By far the majority (95%) specifically responded that there was a lack of documented policy/strategy. The remaining 3% declined to respond. In total, 19% of all municipalities supplied documents in response to our request for evaluations and decisions related to document formats and office applications. However, only 8% of all municipalities supplied relevant documents. Among the documents considered not to be relevant were web publication policies; layout instructions; and instructions for how to write documents. It should be noted that no municipality provided a TCO analysis which considered exit costs related to a possible selection of a proprietary document format. A clear majority (92%) of all municipalities recommend and support MS Office as the primary office application in their municipality for writing office documents; 5% of all municipalities did not mention any office application, or declined to respond on this point. Most municipalities primarily recommend and support only one office suite for writing office documents. Overall, 86% of all municipalities only recommend and support MS Office in their administration, and 3% only recommend and support OpenOffice.org. A number of municipalities recommend a combination for their own administration: 5% a combination of MS Office and OpenOffice.org, and 1% a combination of MS Office and StarOffice. Another 4% recommend MS Office for their administration, but OpenOffice.org for (some or all of) their schools (see Table 2). Table 2: Preferences for office applications <table> <thead> <tr> <th>Preferred office suite (tools) for writing office documents</th> <th>Percentage of municipalities</th> </tr> </thead> <tbody> <tr> <td>MS Office</td> <td>86%</td> </tr> <tr> <td>OpenOffice.org</td> <td>3%</td> </tr> <tr> <td>MS Office &amp; OpenOffice.org</td> <td>5%</td> </tr> <tr> <td>MS Office &amp; StarOffice</td> <td>1%</td> </tr> <tr> <td>MS Office (for administration) &amp; OpenOffice (for schools)</td> <td>4%</td> </tr> </tbody> </table> With few exceptions, municipalities do not undertake any evaluation of either document formats or office applications before adoption. For example, one municipality responded: “No formal, political decision exists; neither is there any documentation or evaluation.” Further, the lack of a documented decision related to the selection or procurement of an office application is common to most municipalities. In some, decisions are taken locally with roll-out throughout the organisation without any evaluation: “The decision was taken by our IT advisory board; no direct evaluation was done. An organisation-wide adoption was made for all units.” In some municipalities, the lack of documented evaluations and decisions make the authority defensive, so that except for supplying a copy of the signed contract with their supplier they refuse to elaborate: “Referring to the above, we report that the procurement of our office suite was done through the Select Agreement. We decided on Microsoft Office and attach the agreement with Microsoft. We decline to answer your questions.” Of the municipalities claiming to do some kind of evaluation, most seem totally dependent on processes for IT procurement provided by central agencies for public sector procurement in Sweden, such as Kommentus and Kammarkollegiet. For example, such dependency is clearly illustrated in this response from one municipality: “There has been no local procurement as we participate in SKL Kommentus AB’s and Microsoft’s Select Agreement.” These central agencies are dedicated to supporting municipalities and other public sector organisations by establishing central contracts from which each municipality calls off licences for office applications. For example, one municipality cites the evaluation performed by the central agency in their response on evaluation, stating that they “have used the coordinated procurement of software (Microsoft Select) by Kommentus since the mid-1990s. Common evaluation criteria include price, delivery times and other parameters.” From their complete response it was made clear that the evaluation performed by Kommentus has been their only evaluation, which implies that they have been dependent upon this centrally performed evaluation for around fifteen years. Several municipalities gave similar responses. There is evidence of a common view that some form of evaluation of the office application itself (i.e. the product) is being performed in such central procurement activities. However, the evaluation of office applications undertaken by Kammarkollegiet and Kommentus does not address functionality, licensing or pricing of office applications. Instead, their evaluation is entirely focused on evaluating the reseller. Hence, even if a municipality signs such a central procurement agreement, there is still a need for them to undertake their own evaluation and analysis of document formats and office applications in order to assess the product before adoption. Amongst the municipalities that actually have undertaken evaluations that consider file formats, one responded that a decision was made “to standardize on file format, rather than product.” A few municipalities report that they have initiated work on developing a policy for document formats: “We are working on developing a policy document that describes how and in what format external document are communicated. We will certainly decide that documents that should not be edited must be in PDF format and others must be sent in a non-proprietary format, RTF or possibly odf. Today we have .doc as the document default.” Overall, we found that a clear minority (1%) of all municipalities have considered format prior to purchasing office application. Amongst municipalities that have evaluated applications there are mixed views on applications, and outcomes of evaluations differ. For example, a municipality that evaluated OpenOffice.org found that it fulfilled their needs: “Since OpenOffice has all the required features and also implied a financial saving the choice has not been difficult.” On the other hand, a municipality that introduced MS Office concluded differently and recommended MS Office 2007 after their evaluation: “(Microsoft Office) was introduced in the mid-1990s and was evaluated in 2007, along with OpenOffice 2.4 … Primarily we recommend MS Office 2007.” This further reinforces the need for local evaluation. From the responses it was clear that there is considerable confusion amongst respondents related to the difference between application and file format. Amongst the responses concerning application, respondents mentioned specific names of suppliers and applications (in almost all such cases the responses included one or both of “Microsoft” and “Word”), whereas in other cases responses referred to specific versions of a specific office suite (e.g. “MS Office Word 2007”). Regarding responses for file formats, respondents mentioned suppliers (e.g. “Microsoft”), applications (e.g. “Word”), and formats (e.g. “Microsoft formats”), and in several cases initially gave incomplete, unclear, and confused responses. In general, from the number of requests for clarification (via email and over the telephone) we note that many respondents do not see a difference between applications and a file formats. Most municipalities primarily focus their attention on adopting an office application; the file format issue is treated as a consequence of the application choice. For example, one municipality responded that they consider applications as standards and have decided to use these with their ‘default’ file formats: “(The municipality) views Microsoft Word and Adobe (i.e. doc and pdf) as de facto standards and has chosen to use them without major evaluation.” Several others acknowledge that they lack a policy on document formats, but respond that the choice of format is implicitly determined from the choice of application: “We do not have any specific document that regulates document formats. Instead it is determined over time by monitoring the software version agreed within the municipal organization.” Yet other municipalities report that, without a decision, they just use the ‘default’ format which is supported by their application: “there is no written decision with regard to document formats, but in practice .docx is the default setting.” A number of municipalities have a practice of renewing licenses. Renewal of licences is usually being done without evaluation, perhaps over many years. In many cases, the procurement decision dates from a very long time ago. In other cases, municipalities use centrally procured agreements for renewal of licenses (so it is not considered a new procurement). For example, one municipality responded: “We have not bought the software, rather we have held licenses since 1992. These licenses have been extended since then and upgraded on a continuous basis. No procurement was done in 1992.” A different municipality adopted a proprietary product and the office suite has not been evaluated since then: “In 1997 it was decided that the municipality would use the zac-concept (zero management concept) which is a Microsoft-oriented approach. Since then, the Microsoft platform has not been evaluated. Procurements that we do therefore are for MS Office licenses.” Evaluation of file formats and office applications for a municipality cannot be undertaken in isolation of already adopted IT-systems due to various kinds of potential lock-in problems. Therefore, any evaluation and adoption of an office suite needs to consider other systems which have already been adopted. Several responses in the survey indicate that other systems already in use in the municipalities are perceived to dictate requirements on the document format and the office application. Hence, the responses indicate several examples of different kinds of lock-in scenarios, including format lock-in and vendor lock-in. Most such systems require the proprietary .doc format, which makes migration to the open document format (ODF) difficult. For example, one municipality responded that “many of the IT systems that we already use, or that we intend to procure within the administrative sections, are integrated with, and in some cases totally dependent on, functionality and components in MS Office.” Interoperability is critical for municipalities, but several responses indicate that such vendor lock-in is problematic. As illustrated by one respondent: “Today, suppliers of enterprise support systems to the municipalities are tightly tied to Microsoft software. This means that in practice it is very difficult to use open source software to break the hegemony that exists.” In many municipalities a different policy is adopted in schools since interoperability problems related to other legacy systems in the municipality is less of an issue. Overall, our responses indicate that in municipalities where there is less perceived lock-in they are more open to alternatives, as illustrated by this response from one municipality: “Within administration, where application providers have selected the Microsoft track, we are forced to use their office suite. In schools, only OpenOffice is used.” Other responses showed that evaluation for schools in some cases is based on other factors for office applications: “the discussion at the time was that Microsoft had the largest market share amongst companies and municipalities and that it was a good platform for students to learn”. The practice of sending out and receiving documents varies. Although several municipalities accept PDF there is a clear dominance of using proprietary document formats. For example, one municipality responded that: “We send out documents in the format in which it is easiest to send them. In most cases, this is .pdf or .doc.” Two municipalities go so far as to expose, on their public website, which formats they accept: “(XXX) municipality can only receive files which are in one of the following formats: .doc, .txt, .pdf, .xls”. There is evidence of a limited but increasing awareness of issues related to document format and application options, including archiving. Some municipalities are beginning to separate out the issue of application from format, and are looking towards archiving needs, as illustrated by this response: “Open, platform independent, and archive secure file and document formats are important.” In addition to the vast majority of municipalities that use the proprietary .doc format for external and internal communication there is also a small group using ODF as a format for internal communication. One municipality responded: “If you are intending to send internally, it must be in ODF format.” However, in this group .doc is still used for communication with citizens. Amongst municipalities that have adopted ODF, responses show an awareness of the need to be flexible and behave accordingly, as illustrated by the response from one municipality: “Internally, we use ODF. In external contact with partners, we are flexible and can adapt to who we are corresponding with, such as using .doc, etc.” 6. Recommendation for Practice According to the results of the study, municipalities (or some other national public sector organisation) must take responsibility for the evaluation of both document formats and office applications before adoption. Evaluations should be conducted according to the specific needs of each municipality and its outcome should always be documented. A municipality cannot and should not solely rely on central purchasing organisations for setting policy and for analysis of their own requirements. Any decision based on evaluation outcomes should be documented, and renewal of licenses should be treated in the same way as an initial procurement. Further, evaluation should be undertaken on a regular basis, and at least before each major adoption decision. Education policy should not be dictated by such things as current market share for office applications. Evaluation of document formats should always precede decisions on application and should include interoperability and lock-in considerations. Enterprise support applications should not be procured if they dictate the use of a specific proprietary document format or office application. Further, when assessing total cost of ownership the analysis should include consideration of exit costs in the procurement. Long-term digital archiving is a significant issue for both municipalities and citizens. It is tightly coupled with formats, both for preservation and long-term accessibility. A decision on formats is a policy decision, and must not simply be considered as a ‘technical’ issue that follows from an adoption of a specific office application. Municipalities should standardise (and base their procurements) on open formats, not on specific office applications. Citizens should not be expected to buy proprietary software in order to communicate with municipalities; any policy on format must specifically address this point, and also any implications of differences between external and internal communication practices. From this, we recommend that citizens must be able to communicate with municipalities using open formats. 7. Conclusions This paper has reported on problems for many Swedish governmental organisations to communicate in open formats. It specifically reports from an investigation into current practice and policy formulation which has led to this situation in one sector – local government. There are many reasons for the reported problems, including a lack of leadership, awareness and know-how amongst practitioners and those responsible at different levels in Swedish municipalities and other public sector organisations. Most municipalities do not undertake (or even initiate) an evaluation before procurement of software and adoption of document formats. In responses, reference is often made to central procurement agencies, and a number of municipalities seem to misinterpret both the scope and focus of evaluation. undertaken by those agencies. Further, it seems that purchasing of application suites is largely a matter of history rather than strategic decisions. In some municipalities specific applications are named in procurements, which is in conflict with EU directives. This implies that many municipalities have made themselves over-reliant upon central agencies. Each policy/strategy document received from a municipality was analysed to reveal how policies and strategies related to document formats were considered. However, some municipalities provided documents which did not cover document formats, and some responses indicated considerable confusion. In conclusion, we find that there is little or no evidence of consideration given to document formats when municipalities procure software. In a large majority of cases there is no formal evaluation underpinning procurement decisions and no documentation of decisions. The study highlights a lack of strategic decision making with respect to accessibility, and a resultant lack of transparency with respect to ICT procurement. References **Author** **Bjorn Lundell** University of Skövde, Sweden [bjorn.lundell@his.se](mailto:bjorn.lundell@his.se)
Rev. Richard Bury b. 28-Nov-1792, Manchester, England Emigrated to U.S. c1800 with parents William and Mary and brother and sister. Educated at Union College, graduating in 1812 m. 25-Feb-1819, Marietta Gregory at Sand Lake, NY Ordained Episcopal Minister, 24-Oct-1823 in New Brunswick, NJ by the Episcopal Bishop of NJ. d. 21-Jul-1875, Cleveland, OH Rector, Christ Church, Duanesburg, NY from 10-Feb-1823 to Dec-1827 His father, William Bury and young son, Edward Augustus who both d. in 1823, are bur- ried in the Christ Church churchyard. The above is taken from a photograph of an oil painting of the Rev. Richard Bury, now in the possession Mrs. James Bohar of Piedmont, CA. The entry for William is an immediate friend of William Pitt. The therefore, it's not clear where he was born. It's much harder to secure the will, a will of Benjamin, who did not marry. There was a William or Benjamin, who was married to a woman named Elizabeth, who was born in the late 17th century. The will was written in 1772 and recorded in 1774. He was born at Tredwell, Cambridgeshire, England. He was married three times, with children. William was the eldest of four children. He was born in the late 17th century. His parents were John and Hannah Barnett. Their first child was born in 1749. William's birthplace is unknown. He appears in the records of Manchester, where he was a sailor. He was married twice, to Mary Barnett and Mary Barret. The family was involved in fishing and trade. William's father was a sailor and fisherman. The family was involved in the fishing industry. William was born in the late 17th century. 12. Ery thr. William M. Barnett, Mary Ery thr. William M. Barnett, Mary The most recent of all our immigrant ancestors to America, William, the second of our family in America, was born in the late 17th century. The family was involved in fishing and trade. William was born in the late 17th century. The family was involved in the fishing industry. William was born in the late 17th century. The family was involved in fishing and trade. William was born in the late 17th century. Rev. William, sister Sarah and mother Hannah are all buried in the churchyard at Eccles.[318] Another Barrett sister, who first married a Mr. Harker and second married a Lord, Secured (this must have been through the courts) to her own three children, property which had been promised by Sarah to be divided between her sister's three children and the three children of William and Mary Bury; The Barretts were also said to have resided in Derby, Derbyshire, England which is about 25 miles south of Tideswell. William and Mary (Barrett) Bury had five children, of which three survived.[327] All were probably born in Manchester or Eccles. 1. Hannah b. 18-Nov-1762 d. 03-Sep-1839 of Grosbeig, Be, aged 74 years 9 months, 30 days. She married once and is buried in the Horace Grey plot at Elwood Cemetery in Detroit, MI. 2. John b. 03-Jun-1763, red hair, a tall man. A John Andrew Bury, 13 Apr 1789, Manchester, Lincs, is of Wm. and Mary Bury d. 19 Apr 1819 at One Chicks at Detroit. He also married and is buried in the Grey plot at Elwood. He may be the John A. Bury & Co. advertising "Tobacco, Speros & C" in 1812 & 13 in the Columbian Gazette in Utica, NY (1812). 3. Betty b. 22-Jul-1761, probably the dau. 9. Richard b. 29-Nov-1769, see below. In 1798 or 1800, William Bury bought his wife's three children to Boston, MA. Both dates are mentioned in Richard Alfred Bury's memoirs, but the Rovero style silver teapot brought from England and inscribed "Bury" and "1800" would seem to commemorate the latter date. There he engaged in business as a woolen merchant and the following advertisement appearing in J. Russell's Gazette, Boston, 28-Aug-1801 gives a good idea of his business. --- Bury Family (Main Line) John grants power of attorney to his two nephews, Theodore Bury and Richard Augustus Bury, "son or his brother Richard" to go after the goods. I suspect that nothing came of it. Maybe John's son-in-law Richard Bury or Simon Boley got it all. Grandfather had a lot of papers relating to a trip his uncle John Andrew took to England in an endeavor to claim this property and remarked that "we evidently lost a lot of money and [produced] no return whatever." 13. BURY, RICHARD M. Gregory, Mariette The Rev. Richard Bury was certainly the most accomplished of all of our great-grand-grandparents. There is a wealth of material on him, both in family records and in the Bury files at the Burton Historical Collection at the Detroit Public Library and the Bentley Historical Library at the University of Michigan at Ann Arbor. All of this material was donated by Grandfather Richard Alfred Bury. He has also been written up or mentioned in several local history books and church histories. Born in 1792, he immigrated in 1800, with his family, first to Boston, then in 1805 or thereabouts to Herkimer County, NY where his father attempted to make a living. He was "fitted for college" in the grammar school of Dr. Banks and attended Union College at Schenectady, NY, a non-denominational school founded in 1765 and from which he graduated in 1812. He then began the study of Medicine with Dr. Wing of Albany. One source says he may have served as a "medical attendant" during the War of 1812. He made his living during this time working in the office of the Clerk of the Supreme Court in Albany. Sometimes during this period he decided to minister to men's souls rather than their bodies and commenced the study of divinity under the direction of Rev. Dr. William Lacey of Albany. During this time, Richard and other young men would spend their free time at Sand Lake (now called Crystal Lake) in the Town of Sand Lake about 10 miles east of Albany. --- Bury Family (Main Line) There he met and courted Mariette Gregory, daughter of Dr. Linch M. Gregory, one of his courtship letters survives in the author's archive, dated 10-Nov-1818 from Albany to Sand Lake. Here is an extract excerpt from this long letter (which also shows the beautiful penmanship of Richard): "...Believe this you are not exaggerating a fact, and also that I am not in any capacity to understand the system of dates, particularly when different from the one used in America, I will return to you the best of my ability in the way of my own post office, and after changing the date on one envelope to another, it will be of no great material about one letter. For since I was last heard from his date, I have had my own misfortune, which has kept me from writing for some time. While my most affectionate wishes, which I trust you will receive, I am your loving son, Richard Bury..." Bury Family [Main Line] and remain virtually unchanged (in 1996) from its original design, a most unusual one for an Episcopal church. The seats, in stained pine, face across the long axis of the church towards a high raised pulpit in the center reached by winding stairs and overlooking with a canopy. The altar is backed away in a corner. 223 was a momentous year for Richard and Marietta. They already had two daughters, their first son, Edward Augustus, was born on 10-Feb-1823, and on that same day, he received his appointment to Christ Church. Seven months later on 04-Sep-1823, tragically, Edward died. Shortly thereafter Richard achieved his long sought goal and was ordained an Episcopal priest by Bishop John Cross in Christ Church in New Brunswick, NJ on 24-Oct-1823. He was 31 years old. Not two years later, Richard’s father died at the early age of 63 on 04-Nov-1823. Richard had been supporting him after his business failures. Richard, certainly not a man of many great means at this time, inherited the remains of his son and father in the churchyard at Christ Church, the first to be interred there. Their hand-carved grave stones can still be seen there and are quite legible (in 1996). Richard ministered at Quenamah until late in 1827, and during that time three more children were born. He was called back to Albany and on 12-Nov-1827, organized St. Paul’s Parish, the second Episcopal Church in Albany. Under his leadership a lot was purchased on South Pearl Street, the cornerstone laid by Bishop Robert in 1823 and the building consecrated on 24-Aug-1829. The Church struggled in the early years and Richard resigned in late 1836. The Church building was later sold to the Catholic Church. Richard Alfred Bury wrote in 1825 that there is a stained glass window in the Church at Albany commemorating the Rev. Richard Bury. I assume that it is in the successor Church building. During this time our great-grandfather, Richard Augustus Bury, was born in Albany. From an article in the Detroit Tribune of 28-Nov-1874. "The other day the Episcopalians of Detroit celebrated the ninetieth anniversary of the birth of St. Paul. Among other reminiscences one was by Mrs. C. Towbridge, to the effect that in 1836 there was a raid staged. "There was a Mr. E. L. Shakleston in the woods. He was from Albany. One day he remarked that he knew a man in Albany, who was called the 'good old barber,' and he recommended an application to him. So with 6 children, aged 3 months to 10 years, Richard and Marietta headed for the frontier town of Detroit in 25-May-1839 via the Erie Canal which had just been opened in 1825. Dr. Uloth M. Gregory, Marietta’s father, accompanied them on their trip from Albany to Buffalo. The receipt for their passage (including furniture) on the packet boat "Ehman" for $25 survives. It must have been quite a trip. The historian Bruce Catton has described the canal boat experience. "Journeys on the Erie Canal were crowded. Rates were fantastically low. The boats were large, sailing bogs, inexpensively penny and pounds, the passengers and crew huddled together, often speaking to each other only through the shrieks of a lock. One of the express packets could go a hundred miles in twenty-four hours, as much as an migratory goose could do in a week. The main cabin was narrow, low-ceilinged, noisy as the galley of a ship with stoves and with stoves. It was the men, the cabin-iouls, the sailors, who went down into the lock to get out the oars, the sailors, who went down into the lock to get out the oars, the sailors, who went down into the lock to get out the oars. Surviving this trip, Richard found himself at St. Paul’s which had been founded by the Rev. Fish Cady in 1824. The first church building had been consecrated in 1826. The second church building building had been consecrated in 1839, so Richard did not have to build one. Detroit was still heavily French Catholic. b. Charles Christopher Towbridge was secretary of the Board of Trustees of the University of Michigan from 1881 to 1885 and must have known Richard well. He was later president of the Bank of Michigan and Mayor of Detroit. c. Now in the possession of Virginia Olnick Family. b. Charles Christopher Towbridge was secretary of the Board of Trustees of the University of Michigan from 1881 to 1885 and must have known Richard well. He was later president of the Bank of Michigan and Mayor of Detroit. c. Now in the possession of Virginia Olnick Family. Bury Family [Main Line] This family now increased to eight with the birth of Caroline and Henry Anthony, Richard and Mariette headed to Ogdensburg, NY where he took charge of the Church there. Tragedy struck again with the death of Henry Anthony at just eight months of age. After one year in Ogdensburg, they moved to Potsdam, where in 1836 Trinity Church was formally incorporated and a church building begun. In 1836 at Canton, a few miles southwest of Potsdam, they founded Grace Church [195, p34-45]. Richard was not one to stick around after getting things going and so in 1837 he packed up the family again and returned to Detroit where in 1838 he established Trinity Church. Services were held in the old Capitol Building. The church trustees were so grateful for his help that they commissioned the large oil portraits of Richard and Mariette which hang today (2003) in the Bothe and Hoeler residences. In 1836 forty-three communicants were reported. However, the Church closed that year because of inadequate financial support due to economic conditions. [322, p 70] Unsuccessful in Detroit, he was called to Trinity Church in Cleveland and so in 1840, Richard and Mariette, with seven surviving children, aged now from 7 to 18 years, moved to Cleveland, still a very small town by modern standards. (The author has a letter, dated 1843, with the envelope addressed to "Mrs. Mariette Bury, Cleveland, Ohio") I suspect they traveled from Detroit to Cleveland on a Lake Erie steamer. Things went much better in Cleveland. Trinity Church grew rapidly and in 1847, he organized Grace Parish, holding services in the parlor of his rectory. After getting a start from Richard, a brick house of worship for Grace Church was dedicated in 1849 on the corner of Erie and Huron Streets. Money to build the church was donated on condition that the seats should remain forever free. Known as the "People’s Church," it was the first "free" church in Ohio. [216, p 199] But by then, Richard had moved his family back to Michigan. a. Harris (Jr.) Steak now has this certificate. By the time Richard arrived on Grosse Isle with five of his six surviving children, his mother Hannah was living with his large family. (She may have been with them as early as 1830, because the 1830 Census for Detroit shows a woman 40-50 years old living with them and no doubt Mariette could have used a little help.) Around 1847 the Gray’s home burned to the ground end so they also moved in with the Bury’s for an extended period with two infant daughters. During the 15 years he spent on the island, Richard was never associated with an established Church, but he did continue his ministering holding services in his parlor and he performed quite a few baptisms and marriages, even some after he had left and returned for visits with his children. He and Mariette frequently returned to Cleveland during this time as the letters show. Grosse Isle is located just across the river east of the town of Trenton and in 1847, Richard replaced the Rev. Charles Fox (who had replaced him at St. Paul’s) at the parish of St. Thomas in Trenton. But the arduous trip from his home on the southeast side of the island to Trenton, given the rail nature of Richard’s health and the important fact that he was not paid, led him to resign in 1848. Grosse Isle is divided by a waterway called the “Thoroughfare” which separates it into a Northwest portion and a Southeast portion. An Episcopal parish, St. John’s, was organized in 1850 in the Northwest portion and Richard probably assisted, but he is not in the records. Those living south of the Thoroughfare desired their own facility and Richard attempted to form the Trinity Parish there. He held services in his home, and performed marriages recorded in Trinity Parish. Even though some other ministers attempted to continue the work, Trinity folded during the Civil War after Richard had left. Later this area of the island was served by St. James, established in 1886, but Richard was long gone by then. During this time on the Island, as his children were becoming adults and marrying, Richard made his living by selling off portions of the acreage and selling it’s produce, mainly fruit and wood and periodically performing ministerial functions in both anchor and parishes in Michigan, Ohio, Pennsylvania and New York. Mariette’s sister Emily Washington Gregory, in Cleveland in 1829, had married Samuel H. Mather. He was a 1834 Dartmouth law graduate, who after practicing law in Cleveland, founded the Society for Savings, a Savings Bank of some prominence. (Their son Frederick Gregory Mather wrote the monumental "Reliquiae of 1776 from Long Island to Connecticut" [264] which the author has used in this work.) Richard’s son Theodore early on went to work for his uncle and spent many years at the Society for Savings. In 1851, Richard opened his Grosse Ile home “standing at perhaps the most beautiful point on the island” to boarders who would come down from Detroit during the summer for a few days in the country. Some of these were people whom he had known at St. Paul’s. This led to the expansion of his home into the “Island House Hotel” which ‘involved (struggled for) several years, usually under the direction of one of Richard’s sons or sons-in-law. With the expansion, it could handle up to 100 visitors. A cottage on the premises was always reserved for the Bury’s who were frequently away, usually in Cleveland. In 1861 the Island Hotel burned to the ground and Richard sold his interest and returned to Cleveland permanently. During 1858, Richard Augustus, who had married in 1854, moved permanently off-island to Adrian, MI. Only the Gray’s and son William’s family remained on the island. The Gray’s home still stands and is still known today as “Grey Gables.” During his stay on Grosse Ile, Richard kept a “Farm Journal” which is now at the Beiers Historical Library in Ann Arbor. The comings and goings of the family are recorded there with long lists of letters written (but not of the letters). Included is Dr. Uriah M. Gregory’s recipe for cough pills: - 1/2 teaspoon - 2 oz. water - 2 oz. sugar of lead - 4th White pepper Just contemplating a dose of that probably cured many coughs! In 1843 the Farm Journal notes that Richard wrote to Leonard Jerome, Esq. in Rochester, NY. It would be interesting to know what that letter to Wrenton S. Churchil’s grandfather contained. In Sep-1861, Mariette died in Cleveland, aged 68, of pneumonia. What a life she led! Born in the relatively civilized town of Dover, NY her father took her to the primitive settlement of Sand Lake from where later Richard took her to the frontier towns of Detroit and Cleveland all while nurturing a large family and numerous (Bury) relatives! She was much loved by all her family. Her name lives on, six generations later, in Michael Gregory Flynn. The Civil War commenced in 1861 and had some impact on the Bury family. Isabella Swan says that Richard’s eldest son William (then 37 years old) joined the 1st Michigan Cavalry (the same unit Dr. Amos Kendall Smith, joined) on 19-Aug-1861 for three years and was commissioned 2nd Lt. and made battalion quartermaster, but was discharged 09-Sep-1862, reason unknown. However, I can find no trace of him in the records for the 1st Cavalry or any other Michigan unit. Richard’s son-in-law, Horace Gray, did serve with distinction as an officer in the 4th Michigan Cavalry. Theodore and Richard Augustus, both over 30 when the war commenced, never served. Six months after Mariette died Richard married Rev. Juvish Fitzh on 25-Feb-1862, the widow of an Episcopal minister. Later that year Richard was in Flushing, NY perhaps visiting his son-in-law. Rev. David Dovers Gregory (who was also a first cousin of Mariette’s). His first responsibilities in Cleveland were at St. Paul’s, but in 1862 he moved to St. James Parish of which he was rector until 1872, when ill-health obliged him to retire at age 80, "then a grateful and appreciative Church provided an ample stipend for his remaining years." Richard, Mariette and their son Charles were all buried in the Erie Street Cemetery in Cleveland, but 1908 this cemetery was to be abandoned and so the remains were disinterred, the few bones cremated and the ashes brought to Detroit and buried in the Horace Gray lot at Elmwood Cemetery. Richard Alfred Bury was 9 years old when his grandfather died but he remembered seeing his grandfather at various times and remembered his fine appearance, snow white hair and beard and fine manners, and that he never spoke a cross word. The following is an excerpt from a memoir to Richard which appeared in the "Standard of the Cross", 14 Aug 1879, a publication of the Episcopal diocese in Cleveland: Oh, what a faith he had! What love for Christ and the people, what simplicity and trustfulness, what consideration for others, and in delineation of all that human humility, what gentleness, patience, and wisdom, and it was the combination of all of these with an inexpressible love for God which made the character of this old gentleman. His love for the Lord was so great and so constant that it had permeated every pore of his being, and in every action, and in every word, and in every look of his face. It was apparent to everyone who knew him, and it was a great thing to know him. It is no wonder he was called "the Good Mr. Bury. Children of Richard and Katherine: 2. Frances Elizabeth, 3. 9-Nov-1841, d. 9-Oct-1844, d. 24-May-1845, Groose, Jane, M., Children. 4. Elizabeth, b. 24-May-1845, Groose, Jane, M., d. 26-Dec-1846, Groose, Jane, M., (daughters), in Groose, Jane, M., Children. 5. Charles Edward, b. 27-Jun-1853, d. 18-Sep-1892, Groose, Jane, M., Children. 6. Sarah Elizabeth, b. 24-Dec-1857, Groose, Jane, M., Children. 9. Horace Gray Bury, b. 24-Apr-1865, Groose, Jane, M., Children. 12. Charles Augustus Bury, b. 22-Sept-1874, d. 10-Apr-1874, Groose, Jane, M., Children. Richard Augustus was called variously by his family: ?Augustus, Gus and Gussy. In this sketch I will call him Augustus to distinguish him from the numerous other Bury families. Augustus was 16 when the family moved to Groose in 1854. Prior to that time he had lived in Albany, Detroit, Opelousas, Potosi, Detroit again, and Cleveland. When in Detroit the 2nd time and possibly after the family moved to Cleveland, Augustus educated in the Groose Isle School of the Rev. Moses Hoge Hunter who earlier had served at Trinity in Monroe and preached at Old St. Paul's in Detroit and was certainly, although some 20 years younger, a close acquaintance of the Rev. Richard Bury. The charge for school, including boarding, was $150 per year, but the Rev. Richard may have been given a special deal. Hunter's school was a powerful influence on his students. --- 1. At his death and in the family and I believe in the possession of Rev. Richard Augustus m. Charlotte Caroline Louisa. All other data presented by the family and which may be found in the Bury Genealogy if the author ever finished the work. was a member of Michigan Forestry. Ancient Accepted Scottish Rite, and was made a member of the Supreme Council of Sovereign Grand Inspectors of the Thirty-third Degree, at Boston on 28-Aug-1872. The author has a handsome gold, onyx and diamond masonic egg pendulum that belonged to Augusta. On 28-Feb-1882, Augustus' wife of 28 years, Caroline, died at the young age of 50, just two weeks after her mother, Louisa. (Kimball) Chotele died in her care. A year later on 27-Mar-1883, Augustus married Mrs. Mary Hoag, who survived him. In 1883, Augustus, accompanied by his son Richard Alfred, exhibited at the Michigan Pavilion at the Chicago World’s Fair, the largest piece of white pine ever cut in the State of Michigan, a solid piece of wood, a little over 2 1/2 ft wide and about 14 ft long and about an inch thick. When they returned home, it was cut into three pieces and two of the pieces were made into pic-nic tables. The table that survives in the family, served as the first dining room table for Richard Alfred after he married, and again as the first dining room table for Richard Alfred’s daughter Frances when she married Arno Smith. And again when the author first married. It has been used as a picnic table, serving the outdoors for years (and has barbeque iron burners to show for it), a basement laundry table, a school studies desk for the author and presently serves as a breakfast table for the author. Augustus’ death on 06-Jun-1902 at 72 was a blow to the Adrian community. The city council passed the following resolution: Death having removed from our midst, our venerable ex-Mayor, Hon. R. A. Bury, we, the common council of the city of Adrian, deem it fitting and proper to pay him public tribute. Mr. Bury was a man of sterling worth and character, uncomprising and fearless in defense of right, uncompromisingly honest and incorruptible in all dealings with all men. His life has been well spent. His example may well be emulated by all. The flag of the city hall and at No. 1 engine house were placed at half-staff, and Mr. Bury’s portrait in the city council chamber will be appropriately draped. It was signed, among others, by J. B. Morden (q.v.). His funeral was impressive. As presiding officer, Adrian commander No. 4, comprising fifty members, headed by the Padminister, proceeded to [adjudicate] residence on Quaker street, where they were soon joined by several officers and past members of the city council. The commander and his band were in uniform, accompanied by the entire membership of the Daughters of the American Revolution. The remains were in the front of the parade, the enclosed cover and accompanied by a military band in full uniform with appropriate flags. The remains were in the front of the parade, the enclosed cover and accompanied by a military band in full uniform with appropriate flags. The military band was at the rear of the, the military band was at the rear of the, and the mortuary train at the rear of the procession. The military band was at the rear of the, and the mortuary train at the rear of the, and the procession. The funeral train took its way to the church. Following the services the body was escorted to the railroad where the impressive train of the Ohio and Lake Erie Railway Company was pulled in and the funeral train continued to the cemetery where the remains were interred in the Adrian Cemetery. Children of Augustus and Caroline 1. Frank Chotele, b. 28-Sep-1859, Adrian, MI; d. 17-March-1866, Adrian, MI; m. 24-Oct-1886, Mary E. Moore, Adrian, MI; 2 children. 2. Albert Chotele, b. 17-Jan-1861, Adrian, MI; d. 24-Dec-1933, Adrian, MI; m. 17-Oct-1885, Anna E. Moore, Adrian, MI; no children. 3. Louis Chotele, b. 26-Jan-1863, Adrian, MI; d. 9-Mar-1938, Adrian, MI; m. 24-Oct-1886, Mary E. Moore, Adrian, MI; 2 children. 4. Richard Alfred Chotele, b. 27-Oct-1864, Adrian, MI; no children. 5. Eliza Chotele, b. 17-Oct-1866, Adrian, MI; d. 24-Dec-1933, Adrian, MI; m. 24-Oct-1886, Mary E. Moore, Adrian, MI; no children. 6. Mary Chotele, b. 24-Oct-1886, Adrian, MI; no children. 15. Bury, Richard Alfred m. Morden, Eliza Maud Richard Alfred was called Fred by his family for distinguish from the other Richards and we will do so in this sketch. His wife used her middle name Maud. Unlike his father and grandfather, Fred enjoyed the stability of being in one place during his youth and lived in Adrian until he was 35 years old. Fred was a popular figure in Adrian as a young man due to his personality and the local prominence of his father. There were many anecdotes about him in the local paper. He enjoyed having somewhat bizarre pictures taken of himself with his friends at the local photography shop. Family lore says that upon graduation from high school, his father gave him a sum of money with which he could go to college or do whatever he wanted. Fred did whatever he wanted and enjoyed life with his Adrian friends. Fred owned a small one-room cottage on Sand Lake (in Lenawee County) and many summer days were spent out there with friends. Sometime during this period Fred was working in damp conditions in a sawmill. He came down with something that robbed him of his hearing and for the rest of his life he could only hear through the assistance of hearing aids. In what must be almost unique in American corporate history for non-owners of a business, Fred succeeded his father as Lumbar Agent and the following byline was sent out: "The Lake Shore & Michigan Southern Railway Company" "Purchasing Agent's Office" "Cleveland, O., February 4th, 1901" "Mr. Fred Bury is appointed Purchasing Agent, vid Mr. R. A. Bury, assigned to other duties." The office of Purchasing Agent is removed from Adrian, Mich., to Cleveland, Ohio and the purchasing of lumber will hereafter be done under the direct supervision of the undersigned. F. H. GREENE, Purchasing Agent In 1924 Fred moved his family to Ann Arbor and bought the house at 1540 Broadway in which he spent the rest of his life and which is so dear to the memory of all of his grandchildren. Fred bought it for $18,500 (equivalent of about $185,000 in 2001 dollars). Later he bought an adjoining lot and I think in total had about three acres. Certainly for the Amos Smith fam- ily, with moves averaging every two years during the 40's and 50's this was "home". The Wayne Smith's did not move as often, but still the annual gatherings of the two families in the summers at 1540 remain fond memories of at least the older two grandchildren in each family and established life long friendships among them. We all acquired a taste for fresh garden vegetables and fruits from the acre of gardens at 1540 which produced abundant raspberries, strawberries, asparagus, tomatoes, currents, cher- ries, pears, apples, etc. etc. All through the efforts of Maud, although Fred liked to take a lot of the credit! There were also beautiful flower gardens throughout the acre- age at 1540. In 1931 the New York Central Railroad decided to close their Detroit office and Fred decided to retire rather than go to New York. Even though he was 65 years old, I don't think it was a welcome development to Fred. He enjoyed the many friends he had made dealing with lumberman throughout the midwest and south. He wrote many of them a letter announcing his retire- ment and we have the thick sheaf of letters written in response expressing condolences, one noting that he was "one of the considerable victims of the "Cheap and Chippy Chopper" beau- tiful machine which has recently been established in New York." Life in the corporation hasn't changed much. However, Fred enjoyed an active retirement, active in a sense, for I think that most of the real work around 1540 was done by Maud. He busied himself with an active correspondence, work- ing on the genealogy of his Gregory, Kimball and Choate grandparents, considerably aided by the fact that there was a published genealogy for the latter two. He carried on a lengthy correspondence with Grant Gregory, author of the Gregory Genealogy and provided him with many details of the NY and Michigan Gregorys. The Gregory Genealogy was published in 1938 and the author of the book you are reading was named Gregory, no doubt because the Gregory genealogy was an active topic of conversation at the time, and I just made it into the book. Fred took an active interest in Michigan history and donated many items in his possession to the Burton Historical Collection at the Detroit Public Library, the Michigan Historical Collections (which became the Bentley Historical Library at the University of Michigan) and old railroad artifacts and photos to the Museum of the New York Central (wherever that is today). Sitting in his chair in the "sun room" at 1540, along side Maud's violets, Fred entertained his grandchildren with stories and fanc- ciful sketches, some drawn without lifting pen from paper. Maud died in 1950 of complications arising from a minor auto accident and his unmarried daughter Virginia ("Ginny") moved into 1540 to look after him until he died in 1953, age 87. The author, who was about 16 when his grandfather died, remembers him as a gentle man with a great sense of humor, spending hours at his secretary/desk typing letters with his two fingered technique. He never saw him wearing anything but a jacket and tie. (It was grandmother that he saw in old clothes working in the garden!) Children of Fred and Maud: i Harriet Louise, b. 03-Mar-1902, Adrian, MI ii Frances Maud, b. 08-Jun-1906, East Cleveland, OH iii Virginia Morden, b. 17-Jun-1909, East Cleveland, OH, d. unm. 16-Mar- 1987, Ann Arbor, MI Harriet m. Wayne Smith, see Frances m. Amos Kendall Smith, see 10. on page 298. a. Through the internet, the author became acquainted with Jackson Gregory, Grant's grandson and was able to send him the interesting correspondence from Grant to Fred. Bishop Oldham to Dedicate St. Paul’s Church Addition At 7:30 P. M. Tomorrow The Rt. Rev. G. Ashton Oldham, Bishop of the Albany Episcopal Diocese, will dedicate the enlarged parish house and new chapel of St. Paul’s Episcopal Church at 7:30 p. m. tomorrow. A special program of music has been arranged by Dr. T. Frederick H. Candly, organist and choirmaster. Constructions and alterations got underway during the summer in order to be ready for the 115th anniversary of the founding of the parish. The parish was started Nov. 12, 1827, in a schoolroom in S. Pearl at a time when there was only one other Episcopal church in Albany, St. Peter’s on State. This was called the English Church at the time. Residents of the South End felt they should have a church nearer their homes and a place where their children could attend Sunday School. The Rev. Richard Hoyt presided at the first meeting and later became first rector. St. Paul’s today has 1,290 communicants and is the largest parish in the Albany Episcopal diocese. CLASS OF 1812 RICHARD BURY. The Rev. Richard Bury lately moved to Ogdensburg, and a subscription paper was set on foot to prove the practicability of extending a call to him. This was probably the first subscription paper gotten up in Potsdam in the interest of the Episcopal Church. "We whose names are hereunto subscribed agree to pay yearly to Mr. Augustus L. Clarkson, or to the vestry of the parish, whenever such vestry shall be organized, the sum opposite to our respective names towards the support of the Rev. Richard Bury, if he officiates in this place as minister of the parish *********" The Rev. Richard Bury was asked to officiate as missionary of Potsdam and Canton with a salary of $700 a year. On the 11th of November, 1834, he removed with his family to Potsdam. Three-fourths of the Sunday services were appropriated to Potsdam and the remainder to Canton. The Rev. Richard Bury born at Manchester, England, November 28, 1792. His parents were Mary Barnet, of Derby, Lancaster-shire, and William Bury. In the year 1800, they came to America, and made Boston their home, his father being an importer of English goods. Five years later they removed to Herkimer county, New York, where in the grammar school of Dr. Banks he was fitted for college. He graduated from Union College in 1812, and then commenced to study medicine with Dr. Wing of Albany, writing at the same time in the office of the Clerk of the Supreme Court in that city. When prepared to practice medicine he decided to devote his life and labor to the cure of men's souls rather than of their bodies, but the knowledge of the science was of great service to him in his visits to the poor, as well as in his family. He studied theology under the direction of Rev. Dr. Lacey, of Albany, and was ordained deacon by Bishop Croes of New Jersey, and priest by Bishop Hobart in 1823, and began his work of the ministry of the church at Duanesburg, N. Y., where he remained five years. He then removed to Albany and organized St. Paul's Church on the evening of November 12, 1827. It was mainly through his efforts the society was finally established and their first edifice built. In 1830 he was called to the rectorship of St. Paul's Church, Detroit, and went there in May of that year. Beside the care of his own parish, he did much missionary work and organized several parishes in different parts of the State, and obtained the admission of the Diocese of Michigan to the General Convention of 1832. About this time he had a severe illness, and his complete recovery was thought to depend upon his return to the region of the Atlantic Coast. Accordingly, in May, 1833, he left Detroit, and in the autumn took charge of the church at Ogdensburg. After one year he removed to Potsdam, where he incorporated the parish, an account of which is given in the next chapter. Henry Anthon, the infant son of Rev. Richard and Marietta Bury, died December 15, 1834, and was buried the same day in the old burying-ground. A stone reared over the baby's dust, now in Bayside Cemetery, is a mute witness to the tenderness with which he must have been loved. Very imposing was a funeral procession in those days. There was no hearse; the coffin was borne on the shoulders of men, while the pall-bearers walked on either side, holding the pall which covered it. Those on the street would pause and raise their hats as the procession passed by, preceded by a clergyman, slowly winding its way to the old Knowles burying-ground, near what is the Rome, Ogdensburg & Watertown depot. The winter following the arrival of Mr. Bury passed quietly and rapidly. Occasionally, besides his Sunday duties, he held services at the neighboring schoolhouses, as the roads and opportunity permitted. On the 23rd of March, at a meeting held in the "Old Academy," the parish was organized under the name of Trinity Church.**** But a year passed after the consecration the church before the parish lost the earnest zeal and guidance of its Rector. After planting the church at Canton, he returned to Detroit and organized Trinity Church. In 1839, he was called to Trinity Church, Cleveland, where he continued seven years and organized Grace Parish in the parlor of his residence, a short time before he left. Thence he removed to Grosse Island, Mich., where for years he held service every Sunday morning in his parlor, for the benefit of the residents of the island in his neighborhood. In 1859, he returned to Cleveland and took charge of St. Paul's during the vacancy after Dr. Claxton's resignation of that parish and subsequently through the summer of 1861, during the absence of the Rector, the Rev. Dr. Paddock, from illness. In 1862, he revived St. James Parish, of which he was Rector, until compelled to relinquish all labors. His last public service was in St. Paul's church, assisting its late lamented Rector, Rev. T. Brooks, in the Holy Communion, August, 1874. He died in the 83rd year of his age, in the early morning of July 21, 1875. The funeral services were held in St. Paul's Church and were of the most simple character; eight clergymen acted as pall-bearers. The body was taken to the Erie Street Cemetery, Cleveland. An aged friend of his writes: "It was my privilege to know Mr. Bury from his early childhood, and to meet him at various intervals in several of his fields of labor, and finally to stand by his side for an hour, when his feet, swollen with disease, were evidently about to reach the waters of the dividing river. When I was a child, thvxtvnhnuxvtnvtnv&vtvtnv&tvvnvTVTHTHTHTHTH and he yet in his youth, he often came with his fellow-students of Union College (Schenectady) to pass a vacation at Sand Lake, a few miles east of Albany. The rich melody of his flute® playing comes back most clearly as it floated over the quiet waters of the lake; or echoed from the hill-sides. I do not think he was then a professor of religion; but his manner was so genial, so gentle, so circumspect, as to impress my memory most vividly. He was truly genteel in its highest sense, and without pride. "His attention to children, to the aged, and to the poor was so marked and so unusual that I can scarcely believe he had not, even in his childhood, experienced the Grace of God. These characteristics, and many others equally marked, were no less so when the burden and cares of life pressed upon him; and even when age with its infirmities had come he was the same meek, guileless, and cheerful follower of his Lord, always abounding in good works." Portrait accompanies this sketch. History of Trinity Church, Potsdam, N.Y. ppl 17-53 New York & London 1896 Married February 25, 1819, in Sand Lake, N.Y., Mariette Gregory, daughter of Uriah Morehouse and Lucretia (Ely) Gregory. She was born August 3, 1793; died September 5, 1861. He was born Manchester, England, November 28, 1792; died July 21, 1875, son of William and Mary (Barnet) Bury, of Derby, Lancs. Richard migrated to America in 1800; graduated at Union College, 1812; ordained priest in Episcopal church, 1832; rector in Duanesburg, Albany, N.Y., Detroit, Mich., where he organized Trinity Church, Trinity, Grace, St. James' and St. Paul's, Cleveland; helped organize 1835 Diocese of Michigan. He married (2) February 25, 1862, Mrs. Zuriah Fitch. Children, except two infants: 2. Elizabeth, b. Albany, Jan. 11, 1822; m. Rev. David Downs Gregory. (a) Frank Choate, b. Sept. 5, 1855; d. May 10, 1911; m. (1) Sept. 13, 1876, Ida Maria Gunculus, b. Mar. 23, 1855; d. Jan. 8, 1882; m. (2) Sept. 5, 1883, Fannie J. Hancock, b. Sept. 11, 1858; d. Nov. 8, 1917. FROM: Gregory Genealogy pp. 224-225. Grant Gregory, comp. Pub. by Compiler. 1938 June 13, 1967 Miss Isabella E. Swan 27740 Southpointe Grosse Ile, Mich. 48138 Dear Miss Swan: Thank you for your letter of June 9th, in which you gave us corrections on data pertaining to Richard Bury, Union College Class of 1812. We are filing it in his folder for future reference. We will appreciate any other information you may be able to give us in the future. Sincerely, Henry J. Swanker Director-Alumni Relations HJS vmct Mr. Henry J. Swanker Alumni Office Union College Schenectady, N.Y. 12308 Dear Mr. Swanker: June 9, 1967 Thank you for sending the materials on Richard Bury. They add considerably to what I already have and will be very helpful. I do have a few corrections. From the History of Trinity Church, Potsdam: On page 1 of the transcript, re ordination --- the bishops' names should be reversed. From George E. DeMille, Registrar of the Diocese of Albany, I have the following: "He was ordained deacon on October 15, 1822, by Bishop Hobart of New York." "He was ordained priest on October 24, 1823, by Bishop Croes of New Jersey, Bishop Hobart being then in Europe." I have a great deal of information about Mr. Bury's life on Grosse Ile. Too much to review here; a good deal of it will be in my forthcoming history of St. James Parish. Pioneer Families of Cleveland County, New York. In the transcript from the above book the following is in error: Richard Bury came to Detroit in 1830 and left late in 1833 (not nine years as stated). The parents of Richard Bury are buried at Duanesburg. Edward Augustus, b. Fe. 10, 1823, d. Se 4, 1823, buried at Duanesburg. Charles Edward Bury, b. 1825, Albany; d. Jan 31, 1846, buried in Cleveland. Much of my information comes from Mr. Frank B. Woodford, 14161 Warwick Road, Detroit, Mich. 48223. He is a direct descendant and owns the family Bible. Concerning the wife of William A. Bury: Her name was Eliza Reaume (not Resiume, as given in one entry). She was a Grosse Ile girl and a Roman Catholic. That branch of the family became Catholics. On closer inspection I may find other items worth pointing out. Perhaps I will do a sketch of Mr. Bury and his family; a lot about him will appear (someday) in my history of Grosse Ile. Sincerely, (Miss) Isabella E. Swan ISABELLA E. SWAN 27740 SOUTHPOINTE GROSSE ILE, MICHIGAN 48138 May 29, 1967 Union College, Records Office Schnectady, New York Gentlemen: Richard Bury is said to have graduated from Union College in 1812. Can you tell me what degree he received? Apparently he first prepared for a medical career, but whether or not he practiced medicine is unknown to me. He is supposed to have been a "medical assistant" during the War of 1812, and I suspect that any course of study in that field must have been at a later date. However, he switched to theology and was ordained a priest in the Episcopal Church, Diocese of New York, in 1823. I am writing a history of the Church on Grosse Ile and need the information for Mr. Bury's biography. The Registrar, Diocese of Albany, has complete information after the ordination, but no records of his theological training except that he was a candidate for Holy Orders in 1820-21. It is possible that he "read privately" in preparation for the ministry, but if your files disclose any transfer of credits, or letters citing his qualifications that are directed to colleges following his graduation from Union College, I would appreciate having that information. The period of his life between 1812 and 1823 is very hazy. Any facts will be welcomed. If, by chance, you have any need for details of Mr. Bury's life after that period, I will be glad to supply you with a sketch of his life thereafter. He died in 1875. Thank you for whatever assistance you may be able to give. Sincerely, (Miss) ISABELLA E. SWAN June 6, 1967 Miss Isabella E. Swan 27740 Southpointe Grosse Ile, Mich. 48138 Dear Miss Swan: Ms. Swan is said to have graduated from Union College in 1872. Enclosed are copies of all the material Union College has on Richard Bury, Class of 1812. He did prepare for a medical career, the information will be found in the enclosed copies, and then decided to go into the ministry. I am writing at the request of Mr. Swan on Grosse Ile and was interested in this biography. Catholic Bishop, Diocese of Albany, has complete information after the ordination, but no records of his theological training except his certificate for Holy orders from Union College. He received an AB degree from Union College. Sincerely, Henry J. Swanker Director-Alumni Relations The periodical Union College 1823 is very heavy. Any help will be appreciated. HJS vmct enc- CLASS OF 1812 RICHARD BURY The Rev. Richard Bury was the first Rector (St Paul's Episcopal Church, Albany). By the efforts of the vestry, aided by the earnest labors of Mr. Bury, a lot was purchased on South Ferry street, and the first building owned by the society erected. This building still stands, and is known as St. John's Church. This church was consecrated August 24, 1829, by the Right Rev. John H. Hobart, D. D. Mr. Bury resigned in 1830. He died, after filling positions of honor in the church, in Cleveland, in 1872. History of the County of Albany p. 760 Howell & Tenney W. W. Munsell & Co. New York 1886 Rev. RICHARD BURY, A.M., a resident of Detroit, Mich., 1812, was a member of the Philomathean Society. Philomathean Catalogue 1830 who was rector of Old Trinity in 1839, and in later years of Grace P. E. Church, was born in England in 1792, but came to this country with his parents when he was eight years old. His father was William Bury of Bury, near Manchester, Eng.; his mother Mary Barnett Bury. They had three children, only one of whom married. The family lived in New York. Richard, the youngest child, studied medicine and then theology, graduating from Union College in 1812. He became rector of Trinity Church, Albany, then had charge of a parish in Peterdam, N. Y., and in 1830 received a call from St. Paul's, Detroit, the same year that Rev. S. C. Freeman left Cleveland and took charge of St. John's, Detroit. Richard Bury remained in that city nine years and then came to Cleveland. He was married in Sand Lake, N. Y., in 1819, to Mariette Gregory, daughter of Uriah M. Gregory. She was 26 years old, and the groom was her senior only by a year. The children of Richard and Mariette Gregory Bury: Mary F. Bury, b. 1820, in Albany, N. Y.; m. Horace Gray. William A. Bury, b. 1824 in Albany, N. Y.; m. Eliza Reseume (?). Charles Bury, b. 1825 in Albany, N. Y.; unmarried. Theodore Bury, b. 1827 in Albany, N. Y.; m. Miriam Dwight. Richard A. Bury, b. 1830 in Albany, N. Y.; m. 1st Caroline Choate; 2nd. Mary Hoag. Caroline Bury, b. 1831 in Detroit, Mich.; m. George W. Bloodgood. Henry A. Bury, b. 1834 in Detroit, Mich.; unmarried. Rev. Richard Bury came back to Cleveland, to take charge of Grace Church. Mrs. Mariette Bury died in 1861, and two or three years later Mr. Bury married Mrs. Zervia Fitch. She survived him a number of years. He died 1875. The family lived on Clinton street, afterward changed to Brownell, and again to E. 14th street. Miss Mariette Gray of Grosse Island, Mich., is the last survivor of her father's and mother's family. Pioneer Families of Cleveland 1796-1840 Gertrude Van Rensselaer Wickham Rev. Richard Bury began his services February 10, 1823, at $400 per year, which was subsequently increased to $500. He resigned about the last of December, 1827. (Protestant Episcopal Church of Duanesburgh) Hist. of the County of Schenectady p. 177 Howell & Munsell
In the mid 19th century, settlers in the Far West had an ambivalent relationship with the United States government. While they strove vigorously for independence and local governance, they also sought federal funding and assistance in support of their efforts to subdue local Indian groups and develop the region. For its part, the federal government, through its efforts to regulate settlement and establish centralized control over territory and populations, tried to shape its Pacific Coast territories into the vanguard of its national future, and in so doing, redefined its own national identity. In order to incorporate the Pacific Slope, however, the United States had to establish governance methods for this far distant region. Rapid population growth, immigration from around the globe, and a highly mobile population made the process of federal governance along the Pacific more challenging. As home to the first attempts to set up US governance on the Pacific Coast, Oregon became important test case for the establishment of a new form of transcontinental empire and called into question the role of the federal government within the territory. In the first decades of the United States' presence in the Pacific Northwest, federal governance was put to the test in two major ways: 1) through Oregon Territory citizens' objections to territorial rule and their attempts to reform the territorial system, and 2) disagreement over the conduct and funding of Indian wars in both Oregon and Washington Territories. Throughout both debates, political leaders emphasized the independence as well as the virtue of the territory's settlers and the need for the federal government to support the efforts of its Pacific Coast pioneers through funding and public works. Although Oregon settlers saw themselves as Jeffersonian agrarian pioneers, it was only the technological developments of the mid 19th century that made their integration into the United States a possibility. New advances in transportation and communications technology made it possible in 1846 for Oregon Territory to be considered an eventual candidate for statehood. Only a few decades earlier many had believed that the territory would ultimately become a separate republic because its distance from the bulk of United States settlement precluded incorporation. Despite the modern nature of this transcontinental empire, the ideal of the extension of United States' power to Oregon Territory as a tranquil and natural expansion has been enshrined by the reminiscences of Oregon pioneers. One of the region's most prominent citizens, LaFayette Grover, wrote in his memoirs for historian Hubert Howe Bancroft that the “Northwest country was acquired for the United States by the people and not by the government.” Grover was not the only one who separated the concept of “the people” from the concept of government. Oregon political leader and former federal judge Matthew Deady declared in a toast at a banquet in 1886: The Oregon colony was emphatically a popular political movement, conducted by private persons without any recognized head or concerted plan. It was really one of those singular movements of the human race in which numbers of people, without any apparent preconcert of purpose, are moved by some common, controlling impulse, to transport themselves to some unknown and remote region; and having done so proceed at once, as by political habit or instinct, to unite together in civil society and found a state. Such rhetoric distanced Oregonians from their origins, as United States residents, although many of them came from states that had been part of the Old Northwest and already had experience as frontier settlers. It also distanced them from federal government resources on which they depended, including public works and military support. Finally, it distanced them from their place at the vanguard of a new 19th-century form of transcontinental empire being built by the United States. This fledgling empire, which rested on the foundations of older British and Spanish empires along the Pacific, was made possible by new transoceanic ships and the telegraph and driven at least as much by the desire for quick profits and precious metals as by the desire for agrarian expansion. Oregon Territory had always been the goal of the United States' expansion to the Pacific, long before expansion to what was then the obscure Mexican province of California seemed desirable or possible. Even so, individualistic, agrarian rhetoric dominated discussions of the relationship between the Oregon territorial government and the federal government and was thus crucial in shaping the governing structures of the new transcontinental empire. The Lewis and Clark expedition explored the region at the beginning of the 19th century and strengthened the United States' claim, and as early as the 1820s public attention focused on the possibilities of American expansion to this far-off region. In the same decade, repeated bills were submitted to Congress calling on the government to establish a military presence on the Columbia River, extinguish Indian title to land in the region, and encourage settlement. By the 1840s, as immigrants began to trickle into Oregon, the popular press in the East began to pick up on the possibilities of Oregon expansion. In 1845 an editorial in the New York Morning News argued: Oregon can never be (in England) or for her, anything but a mere hunting ground for furs and peltries. But can she ever colonize it with any sort of transplanted population of her own. It is far too remote and too unequal for any such purpose. In our hands... it must fast fill in with a population destined to establish within the life of the existing generation, a noble young empire of the Pacific, vying in all the elements of greatness with that of the already overspreading the Atlantic and the great Mississippi valley. In the presidential election of that year, the acquisition of Oregon Territory became a major campaign issue, with James K. Polk famously employing the slogan “Fifty-Four Forty or Fight.” BY KATHRYN EIGEN **Oregon Territory’s Struggle for Sovereignty** WASHINGTON, D.C., 2005 BY KATHRYN EIGEN COLUMBIA 2 WINTER 2016–17 COLUMBIA 3 WINTER 2016–17 The rhetoric surrounding the expansion of the United States to Oregon proclaimed it to be the inevitable destiny of the United States, but the early years of settlement were filled with unrest and intergovernmental strife. Most notable were the Indian wars that raged throughout Oregon and Washington Territories during the 1840s and 1850s. The course of these battles was a major source of conflict between the settlers and the federal government. Furthermore, despite dependence on the federal government to fund the Indian wars, the southern region of Oregon Territory objected to territorial rule, especially after Washington Territory was split off from it in 1853. Oregon agitated for more local control over the territorial system, a campaign that was only quenched with statehood in 1859. Although the establishment of this government explicitly anticipated the expansion of US rule into the region, the proponents of territorial government emphasized the ability and right of early Oregon settlers to self-government. William Green T’Vault, a prominent early settler, in a speech given before 1846, when division along the 49th parallel allowed the US to extend its governance to the region, told the citizens of Oregon that “[b]y you were created to govern, not to be governed.” The arrival of territorial government did not lead to a dramatic change in the political structure of Oregon, especially since Congress allowed the continuation of all provisional government laws that were not contrary to the United States Constitution. The rhetoric of discussion about territorial governance greatly exaggerated these changes, however. Historian Robert Johannsen has argued that “some in the territory soon became convinced that the territorial government also meant a loss of political rights and a reduction to a ‘colonial’ status.” Oregonians felt that territorial government had deprived them of the right to choose their own leaders and began a movement for territorial self-government. They strove to change the territorial system and argued that the imposition of officials from outside Oregon violated their right to self-government. An April 1851 editorial by Samuel Thurston in the Oregon Statesman declared, “I sincerely wish the people of Oregon, without distinction of party, would unite in memorizing the President to appoint no man to office in Oregon, except he be an Oregon man—one among us.” The next edition of the Statesman reported that a public meeting in Portland protested against the conduct of the territorial judiciary and memorialized President Millard Fillmore “that there are many respectable individuals in Oregon, capable of discharging the duties devolving upon the Judges, as well as of filling any other office under the Territorial Government.” Oregonians also argued against the legitimacy of the territorial system itself, making the territory’s new and thriving newspapers the forum for these debates. A December 1851 editorial in the Oregon Weekly Times (Portland) argued that “[t]hese Territorial systems of government are repugnant to the true spirit of our Constitution, never was it intended that a system be imposed long on Americans, who have the spirit of freedom established by their fathers.” Six years later prominent settler Jesse Applegate wrote to the Oregon Statesman: It is a curious fact that our territories are governed on almost the precise plan of the British Colonial System resided by our ancestors in the war of the Revolution. And the rights of self-government which they so nobly asserted to the world and defended against the whole force of the British Empire have been withdrawn from the people of their own territories. Many of the national political efforts of Oregon’s territorial leaders were directed at the reform of the territorial system. The passage of the Kansas-Nebraska Act in 1854 had significant and lasting effects on the national political development of the United States, but it was also an important political issue in Oregon and Washington Territories. Both had been agitating for greater local control within territorial governments, and the popular sovereignty offered in the Kansas-Nebraska Act seemed to be an important first step in this direction. The desire for self-government also affected political structures within Oregon Territory. The northern part of the territory agitated for separation from the southern part on the grounds that their interests were opposed. As an editorial in northern Oregon’s first newspaper, the Columbian, proclaimed in October 1852, “We must become our own masters, and control the affairs pertaining to our own destiny.” The support of leading political figures in southern Oregon helped the northern regions achieve their goals. In 1853 a letter of Joseph Lane published in the Oregon Spectator and reprinted in the Columbian argued that “Oregon is too large for one Territory or State, and without at least two States are formed out of it, can never be represented as the great interests of that portion of country are entitled to be.” The creation of Washington Territory in 1853 separated out the less developed regions and paved the way for the newly-reduced Oregon Territory to become a state. Although Oregon’s political leaders desired self-government, they were quick to anger when they felt slighted by the federal government. Oregon’s settlers felt that they suffered in comparison to the national attention paid to California in its rapid growing settlements in their Pacific Coast neighbor, California. California had never formed a territorial government; instead, after a brief period of military rule, it transitioned directly to statehood. “California, the favourite ‘golden haired’ sister, has received more from Congress than she expected,” wrote pioneer John A. Anderson to Joseph Lane, Oregon Territory’s first governor, in 1851. Oregon’s settlers believed that the national attention paid to California was hindering their own progress toward statehood. The Oregon Spectator argued in November 1849 that the failure to fill territorial offices in Oregon was delaying the colony’s development: “The value and importance of the American possessions along the Pacific are the subject of general remark throughout the whole of Christendom. And yet many of our most pressing interests are wholly neglected.” The most heated conflicts between territorial/state governments and the federal government occurred over Indian policy. At the same time that Oregon pioneers were striving to achieve more self-governance, they were also initiating and prosecuting a series of armed conflicts with native tribes and calling for federal aid to support these wars. Despite the image of the region as an agricultural paradise, or perhaps because of it, during the 1850s Oregon was the site of some of the most violent and deadly Indian-white warfare that had occurred on the North American continent in the past two centuries. **CONFLICTS BETWEEN IMMIGRANTS AND INDIANS IN OREGON WERE FEED BY THE OREGON Donation Land Act of 1850. The act granted land to settlers who arrived in the region by a certain date, nor did it limit white settlement to those areas that were not occupied by Indian tribes. When conflicts erupted, the Oregon settlers treated their relationships with Indians as a matter of frontier self-defense. They organized into militia groups and, largely supported by territorial officials, conducted their own “defense.” Territorial leaders, however, fully expected that the federal government would provide reimbursements for the expenses of these campaigns. Conflicts between the federal government and territorial officials were most heated over wars in southern Oregon. A series of battles that began in 1853–56 along the Rogue River were largely fought by volunteers who then demanded payment from the federal government for their expenses. Many in the federal government, especially the commander of the Pacific Division at the time, General John Wool, responded by blaming the Oregon settlers for provoking the attacks, something even the law had done so for the purpose of “plundering” the United States Treasury. Until well into the 1860s congressional discussion of Oregon centered mainly on debate over funding for the Oregon Indian wars. In 1852 the annual legislative statement of Oregon’s territorial governor, John P. Coos, summarized the contradictions inherent in the view of Oregon residents about federal governance: > The pioneer in the settlement of the country cannot be neglected by Congress. Their firmness, their hardships, their virtue in journeying across the wilderness, in subduing the land, in contributing to settle the great boundary dispute, will appeal and not in vain, to the generous sentiments of the nation at large. Congress would reward such virtues. It will aid us by liberal appropriations in the development of our resources. Policy, if not magnanimity will dictate them. For whilst such provisions will promote the growth, and advance the prosperity of the Territory, they will at the same time, add to the wealth, extend the usefulness, and enlarge the greatness of the Union itself. Political leaders in the eastern United States saw expansion to Oregon as the beginning of a new stage of American history. While the early political leaders of Oregon Territory agreed, they saw the story of Oregon’s destiny as one they would write for themselves, albeit with federal assistance. During the period of territorial government, when Congress theoretically had the greater control over the direction of affairs in Oregon, its efforts to promote the integration of the territory into rational policy faced more challenges than in any other period. Such conflicts haunted the era of United States expansionism and put the relationship between federal and state governments in the new transcontinental nation to the test. 10 **PROCLAMATION!** *By Geo. Abernethy, Governor of Oregon Territory.* > The Legislature now in session having authorized me to call upon the Citizens of this Territory to rally, on the purpose of carrying on operations against the Cayuse Indians, and to permit them for the numbers committed by them on the residents at Wailtaps: I therefore call on the County headquarters named, to furnish the number of men required of them. This enlistment to be for ten months, unless sooner discharged by proclamation; each man to be fully armed and equipped, to furnish his own horse and outfit and to rendezvous at Oregon City on the 28th inst., when the Company will meet its officers and immediately proceed to Wailtaps. Champoeg County will furnish 40 Men. Tualatin County will furnish 30 Men. Yam Hill County will furnish 20 Men. Polk County will furnish 30 Men. In witness whereof I have hereunto signed my name and sealed the seal of the Territory at Oregon City this 17th day of December, 1847. Geo. Abernethy, Governor. George Abernethy, Oregon’s provis- sional governor (1845–49), issued a call to raise a volunteer militia in response to the murders that took place at the Whitman Mission. This militia went on to participate in the Indian Wars of the 1850s. Kathryn Eigen holds a doctorate in United States history from the University of California, Berkeley, She currently teaches history to community college students in the San Francisco Bay Area. By David F. Martin Tacoma might not immediately come to mind as the likely hometown of nationally and internationally renowned artists. Nonetheless, some of the Northwest’s finest and most innovative artists began their careers or lived for a time in the “City of Destiny.” These include sculptor Allan Clark (1886–1950), painter-illustrator Mac Handainger (1902–1975), printmaker Thomas Hardborth (1897–1948), and photographers Wayne Albee (1882–1917) and Vinita Haffner (1899–1948). The most famous name in glass art alive today, Dale Chihuly (b. 1941) also has his roots in Tacoma. To this illustrious list we must add Peggy Strong, artist and Seattle Times art critic Kenneth Callahan said of her: > Miss Strong is an unusual artist because she is young and she has been successful in pleasing both the public and art juries—no slight accomplishment itself. Her present success has been reached because, throughout her painting, Miss Strong displays a high degree of skill . . . she can handle any subject with equal ease, painting it with mastery and directness in fluid, swinging brushwork . . . and she works very hard and paints a great deal. From the time she was born, Strong (1912–1956) faced a number of physical challenges that countered the promising life of a young woman born into a cultured and educated Tacoma family. Peggy Strong in her Tacoma studio, c. 1939. In the background is a portrait-in-progress of Wayne Brown, who later married Strong’s sister, Bibbts. When Strong attended the University of Washington, the influence of this group had permeated the art department. Two exhibitions sponsored by the study of the work of Alexey Jawlensky (1866–1941), a prominent member of the Blue Four. However, the strongest influence appears to have been the work of Franz Marc (1880–1916), an original member of Der Blaue Reiter who had been killed in action during World War I. Strong’s love of horses and equine subjects were likely what attracted her to Marc’s paintings, and his vibrant use of color and Cubist modeling influenced her work. To further her education, Strong set out at age 20 to study in Paris, the acknowledged center of the art world at that time. She left home to drive across the country to New York, where she planned to depart for France. In August 1913 she began the journey with her boyfriend, Harry Laming, a promi- nent Detroit physician and friend of the family. A tire blow-out between Laramie and Medicine Bow, Wyoming, resulted in a crash that left Laming unhurt but severed Strong’s spine. She was taken to Denver’s Children’s Hospital for immediate medical attention, but the outlook was grim. Surgery saved her life but left her paralyzed from the waist down. While recuperating in her hospital bed, she was unable to draw or paint, but she began carving diminutive sculptures from bars of Ivory Soap held above her head, the soup shavings falling into her eyes. Proctor and Gamble had begun sponsoring national soap-carving competitions beginning in the 1920s, and it is likely she was inspired to participate despite and possibly because of her physical limitations. Strong’s family and friends immediately rallied around her and presented some of her paintings to various art organizations for exhibitions, especially through the Junior League of which she was a very active member. Although confined to a wheelchair, she forged ahead in her painting career, optimistic that she would someday walk again. She was known to drive to Seattle, travel to Denver, and return to Tacoma by train. With her indomitable pluck of one whose work is done from a wheelchair. ...c. 1939. In the background is a portrait-in-progress of Wayne Brown, who later married Strong’s sister Bibbts. When Strong attended the University of Washington, the influence of this group had permeated the art department. Two exhibitions sponsored by the study of the work of Alexey Jawlensky (1866–1941), a prominent member of the Blue Four. However, the strongest influence appears to have been the work of Franz Marc (1880–1916), an original member of Der Blaue Reiter who had been killed in action during World War I. Strong’s love of horses and equine subjects were likely what attracted her to Marc’s paintings, and his vibrant use of color and Cubist modeling influenced her work. To further her education, Strong set out at age 20 to study in Paris, the acknowledged center of the art world at that time. She left home to drive across the country to New York, where she planned to depart for France. In August 1913 she began the journey with her boyfriend, Harry Laming, a prominent Detroit physician and friend of the family. A tire blow-out between Laramie and Medicine Bow, Wyoming, resulted in a crash that left Laming unhurt but severed Strong’s spine. She was taken to Denver’s Children’s Hospital for immediate medical attention, but the outlook was grim. Surgery saved her life but left her paralyzed from the waist down. While recuperating in her hospital bed, she was unable to draw or paint, but she began carving diminutive sculptures from bars of Ivory Soap held above her head, the soup shavings falling into her eyes. Proctor and Gamble had begun sponsoring national soap-carving competitions beginning in the 1920s, and it is likely she was inspired to participate despite and possibly because of her physical limitations. Strong’s family and friends immediately rallied around her and presented some of her paintings to various art organizations for exhibitions, especially through the Junior League, of which she was a very active member. Although confined to a wheelchair, she forged ahead in her painting career, optimistic that she would someday walk again. She was known to drive to Seattle, travel to Denver, and return to Tacoma by train. With her indomitable pluck of one whose work is done from a wheelchair... In 1939, Strong was one of 60 women artists whose work was included in the contemporary art show at the Golden Gate International Exhibition in San Francisco. In November of that year, SAM presented 32 works by one of the great figurative painters of the period, Frederic Taubes (1902–1983). Strong's mother had lured the artist to the Northwest that summer and provided him with room and board in exchange for intensive instruction for her daughter. From Taubes, Strong learned how to grind her own pigments, mix them with various oil mediums, and make her own paints. When the Wenatchee mural was completed, SAM exhibited it along with the working sketches in September 1940. Measuring 18 feet wide by 7 feet tall, the large mural made quite an impression within the art community. When the exhibition concluded, the museum maintained the momentum by presenting the artist with a solo exhibition of her paintings. With the success of her first mural now established, she was commissioned again in 1943 to create a mural for the Naval Officers Club at Dutch Harbor, Alaska. Besides the 12-by-7-foot mural decorating the space above the club bar, Strong created two wooden screens at the entry door, painted on both sides. The mural has since been lost. The following year, Strong, along with her mother and sister, traveled to Europe for an extended stay in several cities. While visiting some of the finest museums, she apparently was moved by the work of Francisco de Zurbarán (1598–1664). His influence can be seen in at least one of her paintings. This compelling composition features a bound, gagged, and shackled woman wearing a hood, perhaps intimating a self-portrait of an imposed monastic existence. Several works with disturbing imagery soon followed, and these later paintings are in direct conflict with the earlier figurative subjects. Where she once detailed the nuances of the human figure and elucidated their individual personality traits, her paintings now often depicted humans as primitive stick figures in unnatural primary and secondary colors. The latter paintings frequently convey a feeling of despair and hopelessness. This change took place when she returned to Tacoma after her trip and began attending services at the Church for the Fellowship of All Peoples. This multi-denominational, inclusive church was cofounded by a group of forward-thinking women artists whose work was included in the contemporary art show at the Golden Gate International Exhibition. where he met Mahatma Gandhi, whose spiritual teachings had a lifelong influence on him. Gandhi implored Thurman to promote a philosophy of nonviolence in the United States as a way of achieving racial and social equality without the threat of physical force. These tenets created a lasting impression on important historical figures ranging from Martin Luther King Jr. to President Barack Obama. Strong and Thurman became close friends and visited at least once a week. Soon the artist embarked on a serious study of various religions, spiritual, and philosophical writings, making copious notes in several binders that she used for inspiration both in her life and her art. Thurman encouraged the study of all philosophies and quests for spiritual growth. Strong, struggling to deal with her physical limitations, tried whatever she could to overcome her paralysis. This led her to a humiliating interaction with an indignant London faith healer who admonished her publicly for failing to stand at his command, and to a meeting with acclaimed American mystic Edgar Cayce (1877–1945) of Virginia Beach, whose writings became the basis for modern New Age philosophies. In addition to his religious profession, Thurman had a lifelong interest in the arts. He sometimes played his clarinet in Strong's studio while she painted and even tried his own hand at painting under her guidance. He attempted to integrate visual arts into the activities of his church and gave Strong a solo exhibition in the early 1950s. He included a small chapter on her in his autobiography, stating: “A superbly gifted artist and portrait painter, she was one of the most resourceful human beings I have ever known. One of the fruits of our long and rich friendship is her portrait of me…” Although she had numerous relationships, Peggy Strong never married and resigned herself to a life without a husband and children. Luckily, her family and close friends supplied her with love and companionship that never wavered. Her health began to decline in the early 1950s, and she developed kidney disease. The portrait of her friend Howard Thurman turned out to be her last. When she could no longer care for herself, she went to live with her brother Charles in Eugene, Oregon, where she died on June 10, 1956. Four months after her death, the Tacoma Junior League sponsored a memorial exhibition of her work at the Tacoma Art League. Since that time, the majority of Peggy Strong's paintings have remained within the family's collections. They were united for an exhibition at the Cascadia Art Museum in Edmonds, September 9, 2016, through January 8, 2017, titled A Spirit Unbound: The Art of Peggy Strong. In reintroducing her work to a wider public audience, the exhibition has recognized her reputation as one of the Northwest's most talented painters and illuminated her unbridled spirit. Black Harris Northwest Mountain Man of Mystery BY R. GREGORY NOKES Moses “Black” Harris was known to tell some pretty tall tales. Perhaps the tallest was the one about a petrified forest he knew of in the American West that had petrified so suddenly, and so without warning, that the birds singing in the tree branches were petrified, too. And not just petrified, but petrified with their mouths open in mid-song! We know a great deal about Harris’s accomplishments but very little about his personal life. He seems to have revealed almost nothing about his background to his friends—not untypical of fur trappers who often spent months at a time with little or no human companionship. As an adult, Harris may have never had a real home until he settled in the Willamette Valley, and once there he remained only a few years. Where did Harris come from? Union County, South Carolina, possibly. Or maybe Kentucky. No record of his birth has been located. Harris was dark-skinned, and there is evidence he was African American. There are also credible historical references to Harris as white—with his skin color described as an aberration. There is one reference to Harris as Native American. Alfred Jacob Miller, best known for his paintings of early Western scenes, painted Harris and described him as “of wavy form, made up of bone and muscle, with a face American wife and children, but kept them secret until he was near death. Even his race has been questioned. Harris was dark-skinned, and there is evidence he was African American. There are also credible historical references to Harris as white—with his skin color described as an aberration. There is one reference to Harris as Native American. Alfred Jacob Miller, best known for his paintings of early Western scenes, painted Harris and described him as “of wavy form, made up of bone and muscle, with a face American wife and children, but kept them secret until he was near death. Even his race has been questioned. Harris was dark-skinned, and there is evidence he was African American. There are also credible historical references to Harris as white—with his skin color described as an aberration. There is one reference to Harris as Native American. Alfred Jacob Miller, best known for his paintings of early Western scenes, painted Harris and described him as “of wavy form, made up of bone and muscle, with a face American wife and children, but kept them secret until he was near death. Even his race has been questioned. Harris was dark-skinned, and there is evidence he was African American. There are also credible historical references to Harris as white—with his skin color described as an aberration. There is one reference to Harris as Native American. Alfred Jacob Miller, best known for his paintings of early Western scenes, painted Harris and described him as “of wavy form, made up of bone and muscle, with a face American wife and children, but kept them secret until he was near death. Harris’s racial origins cannot be proved, but some of the evidence for him as African American lies in the names “Black Harris” and “Black Square,” by which he was known. Apparently composed of tan leather and whip cord, finished off with a peculiar blue black tint, as if gunpowder had been burnt into his face.” Miller did not make specific mention of Harris’s race. Absent documentation, Harris’s racial origins cannot be proved, but some of the evidence for him as African American lies in the names “Black Harris” and “Black Square,” by which he was known. He was once quoted as calling himself “a nigger,” although most of the conversation in which that happened was almost certainly contrived. Durrell Millner, retired professor of black studies at Portland State University, said the nickname of “Black” for Harris was likely a reference to his race, and no one would need the need to add that he was a Negro, colored, or mulatto—the racial descriptions used at the time. My final personal conclusion was that he was indeed “Black” for a pretty simple reason... . . . In the writings of his mountain man contemporaries, that’s what they call him... . . . Those were the usual “fighting words” if he did not consider himself to be that [black], and goodness knows those mountain men didn’t need much of an excuse to start a fight—in effect, he would have been in constant combat. Harris would not have been alone among African Americans who went west as fur trappers and guides, lured by a life of independent isolation and the ability to escape much of the racial hostility prevalent elsewhere. Harris sometimes traveled with James Beckwourth, a prominent trapper who was born to a white slave owner and a black slave mother in Virginia. Others included Edward Rose, a well-known trapper and interpreter described as part African American, part Cherokee, and part white; and Potette Labross, also known as Polite Robiseau. It is possible that Harris may have been born to a slave mother and white father, the same as Beckwourth. If so, it might explain why he said little about his early life. Harris was literate—reflected in occasional letters to newspapers and others—at a time when slaves were generally denied an education. The trapper’s early life is a mystery. He first appears in records in 1822 as a fur trapper with the famed Rocky Mountain Fur Company, trapping for beaver pelts, which were in high demand for a wide variety of hats in North America and Europe. He trapped both independently and for several fur-trapping companies in a career spanning 20 years. Harris would have been with William Ashley, one of the owners of the Rocky Mountain Fur Company, in June 1823 when Ashley suffered what has been described as “the worst disaster in the history of the western fur trade.” Ashley had taken 90 men on two keelboats up the Missouri River from St. Louis. A large force from the Arikara Indian villages attacked the party with rifle fire, while the men were exposed on the riverbank. Casualties among the trappers were 14 dead and 11 injured. During much of his time in the mountains, Harris worked as a so-called free trapper, a category of especially accomplished trappers who worked alone or in small groups. Dale Morgan, biographer of Jedediah Smith, wrote that “the free trapper became the rock on which the [American] fur trade of the West was built.” The best among them might make $1,500 in a good year. A trapper’s work was arduous, requiring work in snow and ice—beaver pelts were at their prime in the coldest months. The trapper maneuvered iron traps into an icy stream near a beaver’s lodge, anchoring the trap with a chain. Using scabs, the trapper would catch a beaver by his feet to drown it. Each trap might be responsible for five to ten trappers. Harris was offended by the presence and practices of the British. Several hundred trappers worked the West for competing companies—three of the biggest were the Rocky Mountain Fur Company, its successor, the American Fur Company, and the British Hudson’s Bay Company, with its major outpost at Fort Vancouver. The first mention of Harris venturing into Oregon was in 1826 when he and Sublette led Ashley’s trapping party through South Pass across the Continental Divide. At the time, everything west of the Rocky Mountains and north of the California border was considered part of the Oregon Country. It was during this period that Harris gained a fondness for Oregon and wanted to see it brought under the American flag. Indeed, he was outraged when, in 1837, the Hudson’s Bay Company acquired Fort Hall—the American-established trading center in present-day Idaho—as part of its strategy to monopolize the fur trade. The Hudson’s Bay Company had waged a two-front campaign aimed at driving American trappers out of the Oregon Country. First, they attempted to create a “fur desert” south of the Columbia by trapping and killing all the beaver. A directive from the company’s London headquarters in March 1827 ordered employees “to hunt as bare as possible all mountain men.” Harris was offended by the presence and practices of the British. ...outburst of patriotic fervor, he wrote to St. Louis businessman Thornton Grimsley, urging formation of a military force to expel the British, along with Native Americans, from the entire region diplomatically by some tribes. By the time American missionaries began emigrating to the Northwest to minister to the tribes, trapping activity had passed its peak, as beaver pelts were no longer in great demand. As an experienced mountain man, Harris was already finding other opportunities. Harris guided supply trains from Missouri to fur trappers gathered at the annual rendezvous—usually held in today's Wyoming—bringing them goods for the next year and returning east with the fur gathered in the previous year. The rendezvous attracted crowds of trappers and hundreds of usually friendly Native Americans. These were typically times of revelry, if not outright mayhem, during which alcohol flowed freely. The Rocky Mountain Fur Company supplied the rendezvous until the company dissolved in 1834, after which the American Fur Company took over until 1840, the last year of the gathering. In 1836, 1838, and 1839, Harris guided caravans that also escorted missionary parties as far as the rendezvous. Narcissa and Marcus Whitman, who established a mission at Waiilatpu, near Walla Walla, were in the 1836 caravan, along with Eliza and Henry Spalding, who established their mission at Lapoai, near Lewiston. The 1838 caravan included Myra and Cushing Eells. One early settler wrote that Harris also escorted Marcus Whitman on his initial scouting mission into the Oregon Country in 1835. While trappers were generally less than pleased to have slower-traveling missionaries tagging along—they bombarded Marcus Whitman with eggs in 1835—Black Harris gained a reputation for being helpful to the missionaries, even charming. Narcissa Whitman wrote that she had invited “Major Harris” and others to tea at an encampment along the Platte River. Bernard DeVoto, in his book Across the Wide Missouri, wrote that Narcissa seemed “delighted” to be in the company of the trappers, and “at a guest[,] in Harris most of all.” Harris also earned Myra Eells’s praise. She wrote in her journal on April 28, 1838, that while many in the supply caravan seemed hostile, Harris was both welcoming and helpful. “Major Harris comes gives us a large piece of pork.” On July 4, Harris reappeared in Eells’s journal after a long absence to scout the trail ahead. “Major Harris comes to us again; says that 9 days out of 11 it rained and snowed constantly since he left us and the snow was 12 to 14 inches deep in the mountains.” Narcissa Whitman described the 1836 caravan as “a moving village” of fur trappers, wagons, and cattle. “If you want to see the camp in motion, look way ahead and see first the pilot [Harris] and the captain, Fitzpatrick, just before him, next the pack animals, all mules, loaded with great packs; soon after you will see the wagons, and in the rear, our company,” she wrote in a letter home. “We all cover quite a space.” Myra Eells was less poetic about the 1838 caravan. “We had much the appearance of a large funeral procession,” she wrote of the 60 men, 200 horses and mules, and 17 carts and wagons. The missionary women had dramatically different experiences at the rendezvous. Narcissa was charmed by the reception from Native American women, probably including trappers’ wives, at the 1836 rendezvous at Horse Creek along the Green River near Pine Dale, Wyoming. As soon as I alighted from my horse, I was met by a company of marauding native women one after another shaking hands and saluting me with a most hearty kiss. This was unexpected and affected me very much. They gave Sister Spalding the same salutation. After we had been seated awhile in the midst of the gazing throng, one of the chiefs . . . came with his wife and very politely introduced her to us. They say they all like us very much, and thank God that they have seen us, and that we have come to live with them. Narcissa had written, following mention of the tea with Harris and others, “I was never so contented and happy before.” Eleven years later, on November 29, 1847, Narcissa and Marcus, with 13 others, were massacred at their mission by members of the Cayuse tribe, who blamed the Whitmans for the diseases that were devastating the tribe. For Myra Eells, the 1838 rendezvous held at the confluence of the Wind River and the Popo Agie proved an appalling experience. She wrote on July 5 that during the previous night as many as 20 “mountain men and Indians” descended on the missionaries’ tent, dancing, beating drums, firing their weapons, and carrying the scalp of a member of the Blackfeet tribe. “If I might make the comparison, I should say that they looked like the emissaries of the Devil worshipp[ing] their own matter.” The episode was repeated the... Harris happened to be in The Dalles when several exhausted riders arrived in September 1845 seeking help for the lost wagon train of Stephen Meek. The following night, "no one could describe the horrible scene they presented. Could not imagine that white men, brought up in a civilized land, can appear to so much imitate the Devil." Myron Eells, in a biography of his father, Cushing Eells, noted that Harris may have been responsible for circulating the news that white women would be at the rendezvous: "Some one who was somewhat friendly to the missionaries, either Dr. Robert Newsell, an independent trader, or a half-breed [sic] named Black Harris, who had learned of this rendezvous of the American Fur Company, had with charcoal written on the old warehouse door, "Cowich [sic] on Wind River and you will find plenty trade, whisky, and white women." In both 1836 and 1838, after escorting the missionaries as far as the rendezvous, Harris appears to have returned to St. Louis, bringing their wagon and oxen back to Illinois the year's catch of beaver pelts. In 1839 he was back on the road with a supply party, helping escort another missionary group toward Oregon. Harris was hired in 1844 as guide, or "pilot," for a wagon train led by Nathaniel Ford, a prominent central Missouri landholder who had fallen on hard times and was lured west by the promise of free land in Oregon's Willamette Valley. Ford's train was one of the largest of the early wagon trains in the area, settling for a time along the Lacamas River in Yamhill County. By chance, he happened to be in The Dalles when several exhausted riders arrived in the Columbia River town in September 1845, seeking help for what became known as the lost wagon train of Stephen Meek. About 1,000 settlers in 200 wagons had been lured by trail guide Stephen Meek's promise that he could save them time and distance on a southwest trek from Fort Hall through eastern and southern Oregon, before turning north into the Willamette Valley. Ostensibly, it was a shorter alternative to the established trail, which was perilous and had led to the Columbia. Meek lost his way, however, and the emigrants wandered for weeks in the Oregon high desert, using their wagon beds as a short-term解决了. Short of food and water, and forage for their cattle, some of the settlers were near collapse when they found themselves stranded near the end of their journey—unable to cross a deep gorge on the Deschutes River about 35 miles south of The Dalles. Meek and some others rode to The Dalles for help. They were first refused—according to several versions—by the Methodist mission there. Meek then found Harris, whom he knew; Harris organized a rescue party with provisions supplied by local tribes. Joel Palmer, the future governor of Idaho, arrived in The Dalles a day after Meek. Palmer had traveled from Missouri over the established trail. Meek had originally been hired to guide the Palmer wagon train when it departed Independence in May. However, at some point Meek left those wagons behind and rode ahead to Fort Hall to organize the wagon train that followed him on his new trail. No doubt, they included some of the Palmer wagons as well as those of other emigrants. Palmer told in his journal how the complicated search of the Meek wagons was accomplished. At this place [The Dalles] they [Meek and the other riders] met an old mountainman, usually called Black Harris, who volunteered his services as a pilot. He in company with several others started in search of the lost company, whom they found reduced to great extremities; their provisions nearly exhausted and the company weakened by exertion, and despair of ever reaching the settlements in the Willamette Valley. They succeeded in finding a place where their [settlers'] cattle could be driven down the river and made to swim across; after crossing[,] the bluff had to be ascended. Great difficulty arose in the attempt to effect a passage with the wagon. The means finally resorted to for the transportation of the families and wagons were novel in the extreme. A large rope was slung across the stream and attached to the rocks on either side; a light wagon bed was suspended from this rope with pulleys, to which ropes were attached; the bed was then winched up to the bank with the families and loading [belonging] in safety across; the wagons were then drawn over the bed of the river by ropes. Palmer said it took two weeks to get everyone across, the last of the rescued settlers reaching The Dalles in mid-October. Palmer said that about 40 emigrants died during the journey or shortly thereafter. But the Harris-led rescue unquestionably saved lives. It was a fortunate coincidence for the Meek party that Harris happened to be in The Dalles and not on his way to the East Coast. Harris had been escorting former Indian agent Elijah White on a mission to Washington, DC, with a copy of Oregon's newly voted-on 1845 Organic Act—in effect, a constitution. Oregon's provisional government hoped to convince Congress to make Oregon a territory, Harris, White, and three others departed Oregon City on or about August 16. However, Harris left White's party soon after in get under way. Newspapers in the east, which closely followed events in Oregon, denounced Harris's actions in leaving White as inexplicable and irresponsible, probably relying on White's account of events. However, there was much more to the story. After White's departure, the provisional government, meeting in Oregon City, withdrew his authority as the official bearer of the Organic Act, making him for manipulating the contents for his own political purposes—he evidently sought to be appointed governor when Oregon became a territory. The provisional government sent the same information to Washington by ship, via the Sandwich Islands (Hawaii). Harris must have concluded he wanted no part of a cross-continent trip that had lost its purpose. He had gone as far as The Dalles and was still there when Meek arrived a few weeks later seeking help. Following the rescue, Harris returned to the Willamette Valley, where he became involved in developing a new wagon road for emigrants to Oregon. He is mentioned in a newspaper article about a Nathaniel Ford-led expedition to find a passage into the Willamette Valley from the south. Ford took out an ad in the Oregon Spectator on April 15, 1846, seeking volunteers. Under the headline, "Over the Mountains," the ad read: "The company to examine for a practicable wagon route from the Willamette valley to Snake river, will rendezvous at the residence of Nat. Ford on the Rednealis[?] so as to be ready to start on the trip on the first day of next May. The contemplated route will be up the Willamette valley, crossing the Cascade mountains south of the three snowy buttes [Three Sisters]. Those agreed to start at the time above mentioned, are Solomon Tetherow, Nathan Ford, Gen. Cornelius Gilliam, Stephen H. L. Meek, and Moses Harris, and many others, it is expected, will be ready by the time above specified. Even with this considerable exploring talent, however, Ford turned back, apparently concerned that he had too few men to meet threats, perceived or real, from tribes encountered on the route. That same May a new expedition was organized, again involving Harris and a dozen others, including Levi Scott and the brothers Jesse and Lindsay Applegate. The Applegates had a special motive for finding a new route into Oregon. Each brother had lost a son in the Columbia River during their journey to Oregon in 1843. This time the explorers met with success, or at least a degree of success. They blazed a rudimentary wagon road south In his last moments Harris whispered to a bystander that away in the mountain fastnesses... among some unknown tribe of Indians, he had a wife and two children... from the Willamette Valley over the Calapooia and Umpqua Mountains, south-east across southern Oregon and northern California into Nevada, then east across Nevada's Black Rock Desert to connect with the established California Trail near the Humboldt River. The California Trail extended north to Fort Hall where it intersected the Oregon Trail. Harris and Jesse Applegate followed the California Trail to Fort Hall to recruit emigrants for the new trail. With Applegate's assurances that the trail was shorter and easier—less dangerous—about 160 emigrant families in nearly 100 wagons signed on. However, the journey did not go well. The emigrants endured thirst in the Black Rock Desert, frequent lack of forage for their cattle, harassment by hostile natives—who shot arrows into their cattle—and unseasonable drenching rains in the Umpqua Mountains. Twelve adults and an unknown number of children died, typhoid fever taking the greatest toll. An unknown number of children died, typhoid fever taking the greatest toll. Responding to angry criticism from some of the emigrants, Harris wrote a long defense in a letter to the Oregon Spectator, printed on November 26, 1849, in which he included a veiled reference to Nathaniel Ford's earlier failed attempt to cross the Cascades. Lindley Applegate blamed much of the early criticism on the Hudson's Bay Company, which had a commercial interest in the Columbia River route. The reference to Nathaniel Ford's earlier failed attempt to cross the Cascades. Lindley Applegate blamed much of the early criticism on the Hudson's Bay Company, which had a commercial interest in the Columbia River route. Whether from disappointment over the criticism, or simply from his restless nature, Harris left Oregon City for Missouri on May 5, 1847. He reached St. Joseph about October 27, after which he evidently resumed trapping for a time—perhaps he had never entirely quit. Harris continued to work as a trap guide. An article in the St. Louis Republican on April 27, 1849—picked up by newspapers nationwide—reported that the first wagon train of a new "Pioneer Line" to California had "secured the services of the celebrated Moses Harris, known to everybody, who has lived in the mountains, or passed the road to California or Oregon." But the article ended with an ominous reference to the "Pioneer Line" to California had "secured the services of the celebrated Moses Harris, known to everybody, who has lived in the mountains, or passed the road to California or Oregon." But the article ended with an ominous reference to the fact that he may have been African American. It seems unlikely that a white fur trapper on the opposite coast would be so remembered. Some well-known trappers who worked alongside Harris wrote or told their experiences later in life, among them Beckwourth, Meek, and Clyman. Perhaps if he had lived, Harris, too, would have shared his experiences. However, it seems more likely this mountain man of mystery would have kept his story to himself. The reference to Harris's advocacy of human rights is one indication that he may have been African American. It seems unlikely that a white fur trapper on the opposite coast would be so remembered. The photo is of a Native American woman teaching basketry classes at her studio in Sequim. Kathey Ervin's assemblage of 59 individual pieces includes a teapot, sugar bowl, creamer, tiered serving plate, and four place settings—made with Western red cedar, Alaskan yellow cedar, reed canary grass, fern stem, rabbit fur, glass, and metal—as well as cedar bark paper napkin rings, carved cedar knives, fork, and spoon, and woven petrified birds. Kathey Ervin is a member of the Wyandotte Tribe of Oklahoma but has lived most of her life in the Pacific Northwest. She gathers her materials in the Northwest and Alaska, using primarily Western red cedar and Alaskan yellow cedar in her work. She teaches basketry classes at her studio in Sequim. Campaign Buttons Reflect Washington’s Political History BY JOHN C. HUGHES Hundreds of political buttons are carefully cataloged and stored in inert polyethylene pockets at the Washington State Historical Society’s Research Center in Tacoma. These buttons are part of the material culture of campaigns dating to the 1890s—mayoral hopefuls, would-be governors, and a few favorite sons with dreams of becoming president. One ordinary looking pin is something special. With the slogan “TRUE TO TRUMAN,” this Truman Democratic Club of Washington pin was produced at Grays Harbor Stamp Works in Aberdeen. The family-owned business is now celebrating its 80th anniversary. The Truman Club’s conservative coalition with headquarters in Seattle, ordered 100,000 seven-eighths-inch “Draft Roosevelt For ’40” campaign pins with a Statue of Liberty theme at $15.50 per thousand. Just one of those handsome little pins fetches two or three times that amount today. Though Democrats have been their most loyal button customers for almost 80 years, Grays Harbor Stamp Works has always solicited work from other parties and welcomed walk-ins of any political persuasion. It produced at least eight of the best-made anti-FDR slogan pins in 1940 when Wendell Willkie was opposing Roosevelt’s bid for a precedent-breaking third term. One Willkie slogan pin declares “100 Million Buttons Can’t Be Wrong.” That “may not have been a gross exaggeration,” according to Roger A. Fischer, author of “Tippecanoe and Trinkets Too,” an excellent book on campaign memorabilia. Supporters cranked out hundreds of thousands of pins, often literally overnight, to fit new events on the campaign trail. When FDR’s son Elliott received a special commission in the Army Air Corps, Willkie knew an array of pins declaring “I Want To Be A Captain Too!” Over the years the Stamp Works produced thousands of pins for Washington’s formidable Senate duo, Warren G. “Maggie” Magnuson and Henry M. “Scoop” Jackson. Jackson was a legitimate presidential contender in 1972. Harbor Stamp Works manufactured thousands of “instant” ratepayer buttons. Recent “counter” buttons produced by Grays Harbor Stamp Works include “Dakakis & Lowey, A Winning Team For Working People,” and “Washington Conservationists for Clinton-Gore-Locke.” Party Murray, Washington’s senior United States senator, chose Grays Harbor Stamp Works to produce an iconic two-and-a-quarter-inch pin for her first campaign in 1992. It features a pair of sneakers, symbolic of her being dismissed easily on as just a “mom in tennis shoes.” Her seat mate, Maria Cantwell, has also had her buttons produced in Aberdeen. State level political pins by other vendors are also highly collectible, with interesting backstories. There is a “Rutte Rosellini Club” pin, c. 1960s, and even an “Impeach Langle” button from the 1950s, but Gardner and his star-crossed predecessor, John Spellman, may be the only two Washington governors to have their images mockingly depicted on political buttons. After Spellman characterized no-new-taxes Republican legislators as “troglodytes,” a three-and-a-half-inch pin from 1982, it became their badge of honor. They distributed three troglodyte pins, one featuring Alley Oop, the comic-strip caveman, crowning Spellman with the state capitol dome. When Gardner faced his own budget crunch four years later, he angered teachers and other state employee unions by offering only a 3% raise. They retaliated with a “Booth Buster” pin. The “Re-elect Dina” buttons, issued by Rossi supporters when he challenged Governor Chris Gib. A second time, are why political keepakes. Rossi lost to Groat by a hotly contested 129 votes in 2004. Collectors cover the FDR portrait pin, “The New Deal–Cowell County, Wash.” and three related coattails. The Roosevelt-Wallgren button from 1940 helped boost New Deal congressman Mor “Moe” Wallgren of Everett to the U.S. Senate. (He became a one-term governor four years later.) “Let’s Buck Ike! Carrwell For Congress” was a winner in 1952 for Eisenhower and a loser for Albert F. Canwell of Spokane. Canwell was the controversial former chairman of a legislative “fact-finding” committee on allegedly un-American activities. Another nifty little 1952 pin helped elect Seattle Republican Tom Felly to Congress. Felly depicted pouting to “BE.” A scarce beauty with a great slogan is a 1920 portrait pin for a presidential hopeful from Spokane, US Senator Miles Poindexter. A crusader against the “Red Menace”—Bolsheviks, Wobblies, and perceived fellow travelers—Poindexter brought up the rear in two GOP primaries, but had one of the best buttons of the election year: “No Red without Roosevelt — Miles Poindexter for President – Government by Law.” In 1904 Washington State Republicans produced a handsome double-portrait button—a “jugate,” in the parlance of the hobby—featuring President Teddy Roosevelt and their candidate for governor, Albert Mead. Roosevelt carried the state in a landslide. Mead, a former mayor of Blaine, rode the Rough Rider’s coattails to upset US Senator George Turner, the heavily favored Democrat. Outsiders in a Promised Land Religious Activists in Pacific Northwest History By Dale E. Soden Corvallis Oregon State University Press, 2015; 320 pages; $24.95, paper. Reviewed by Emily Suzanne Clark. When Mark Silk’s “Religion by Region” series published its volume on the Pacific Northwest in 2004, editors Silk and Patricia O’Connell Killian titled it Religion and Public Life in the Pacific Northwest: The Zone. For the region with the highest percentage of religiously disaffiliated Americans, it is an accurate nickname, but it can obscure part of the story. That is why Dale Soden’s new work, Outsiders in a Promised Land: Religious Activists in Pacific Northwest History, provides an important narrative. Outsiders in a Promised Land illuminates the influence and diversity of religious activism in the region from the late 19th century onward. It is a story that follows many national trends in American religious history, but the activists in the Pacific Northwest spoke with a regional accent. The growth of industry, progressivism, and the Social Gospel, the nativism of the early 20th century and World War II, the hardships of the Great Depression, and the culture wars split of the late 20th century—all appear in the text but differently than they did on the national stage. The region seems isolated from the rest of the nation, and traditional religious institutions do not seem to have the powerful bases that they do elsewhere in the country. This is why Soden refers to the activists as “outsiders.” They are religiously affiliated protestant sectarians, socialists, and critics seeking to shape the region in a more just, more godly way. But they did not always agree on what that looked like. The book is organized chronologically with a focus on cities such as Seattle, Portland, and Spokane. The mid to late 19th century is a story of booming business and sinful male behavior along with education, women, and Victorian society. The influence of the Social Gospel was not too far behind, and this movement sparked cooperation between Protestants, Catholics, and Jews who sought to create a more just and moral society. Attempts at reform continued through the Progressive Era, as amm and especially women tried to rid Pacific Northwest streets of vice. The early 20th century also saw the populacy of the Ku Klux Klan and its anti-Catholicism, which revealed an increasing divide over what constituted a proper, just society. While some in the region reflect national trends of xenophobia toward Asian immigrants and racial intolerance, many of the “outsider” activists desired a more just and equitable society. Soden sees a long history of the culture wars, noting conservatives’ growing concerns about American life in the mid 20th century. Some activists wanted to protect their vision of proper American society while others wanted to extend it to fully include African Americans. The civil rights movement, environmentalism, and liberalism, as well as conservatism and concerns regarding the traditional family rallied activists across denominational lines. Soden concludes with important reflections on the possible futures of religious activism in the region. With his tri-fold focus, Soden’s work reflects the region’s religious diversity, though urban Protestants dominate the work. This is a fascinating story of religious activism in a region typically overlooked in such studies. Written in accessible prose, Outsiders in a Promised Land will appeal to both scholars and interested readers. Emily Suzanne Clark is assistant professor of religious studies at Gonzaga University, author of A Luminous Brotherhood: Afro-Creole Spirituality in 19th-Century New Orleans (2016), and associate editor for the Journal of Southern Religion. --- Dividing the Reservation Atchison, 1912, and the Nez Perce Allotment Diaries and Letters, 1889–1892 By Nicole Tonkovich. Pullman Washington State University Press, 2016; 376 pages; $29.95, paper. Reviewed by Laurie Arnold. This is a story of George Wright’s ruthless campaign to inflict lasting damage upon the defeated number between 400 and 500 warriors. Wright and his men, and the Coeur d’Alenes at the behest of Jesuit missionaries. On the Spokane River. In a break from pillaging, he made peace with the Coeur d’Alenes at the helm of Jesus missions. On his way back to Fort Walla Walla, he encountered more tribal delegations requesting peace. Among these, Wright ordered that a group of warriors including the Yakama chieftain Qualchan be hanged without trial in the most grotesque manner. The native people that Wright intended to subdue and humiliate still survive and maintain their resilient traditions. While other parts of the country deal with Confederate statues, we in the West must confront the naming of areas for soldiers such as Wright. This task forces us to dwell on this American West legacy and the names we hang onto. Carriker drag us back into the fray to remember what happened and ask “why?” In that process, we can perhaps also say “never again.” Ryan W. Booth is a member of the Humanities Washington Board of Trustees. He has a master’s degree in history from Gonzaga University and his doctoral work is from both Southern Methodist University and Washington State University. --- Hang Them All George Wright and the Plateau Indian War Don Carlson’s new book sheds fresh light on an oft-forgotten chapter of United States Army and Native American interactions in the antebellum American West. Cutler carefully describes each encounter in the Plateau Indian Wars from early 1850s transcontinental railroad surveying to George Wright’s brutal death in 1865 to modern-day interpretations of the war by the Plateau tribes. Seen as a larger tale of unratified treaties, settler incursions, petulant governors, and army brass meddling, Wright’s campaign takes on different meanings depending on who is telling the story. Through Wright’s particularly hideous historical actions, the author clearly makes this a moral story about remembrance and legacy. Opening with a sweeping view of the eastern Washington environmental landscape, the story begins with Wright’s early years at West Point and his rise in the United States Army after distinguished service in the US-Mexican War. Wright’s career then languished in the American West until army colonel Edwin Steptoe suffered a humiliating defeat in May 1858 at Pine Creek. Up to this point, Wright’s strict adherence to army discipline never tainted his genial fairness to all those he came into contact with, including Indians. But the army sent Wright to settle the score for Steptoe’s defeat and bring an end to the conflict. Armed with the best equipment the army could supply, he marched his 700 soldiers to the Four Lakes and then to the Spokane Plains to beat the assembled native forces that numbered between 420 and 500 warriors. For Wright, the battle did not end there. He entered into a ruthless campaign to inflict lasting damage upon the defeated tribes, starting with the cruel slaughter of 800 horses. Wright also ordered the destruction of the Indians’ winter food stores along the Spokane River. In a break from pillaging, he made peace with the Coeur d’Alenes at the helm of Jesus missions. On his way back to Fort Walla Walla, he encountered more tribal delegations requesting peace. Among these, Wright ordered that a group of warriors including the Yakama chieftain Qualchan be hanged without trial in the most grotesque manner. The native people that Wright intended to subdue and humiliate still survive and maintain their resilient traditions. While other parts of the country deal with Confederate statues, we in the West must confront the naming of areas for soldiers such as Wright. This task forces us to dwell on this American West legacy and the names we hang onto. Cutler drag us back into the fray to remember what happened and ask “why?” In that process, we can perhaps also say “never again.” Ryan W. Booth is a member of the Humanities Washington Board of Trustees. He has a master’s degree in history from Gonzaga University and his doctoral work is from both Southern Methodist University and Washington State University. --- Outsiders in a Promised Land Religious Activists in Pacific Northwest History By Dale E. Soden. Corvallis Oregon State University Press, 2015; 320 pages; $24.95, paper. Reviewed by Emily Suzanne Clark. No writer understood manual labor in the early industrial North- west better than James Stevens (1892–1971). He spent his youth and ear- liest adulthood as a laborer, and his fiction captures both the grittiness and romance of simple, honest work, testifying to the notion in Robert Frost’s poem “Mowing” that “the fact is the sweetest dream that labor knows.” Stevens was born in Iowa and reared by his Primitive Baptist grandmother. At age 10 he was sent to live on his uncle’s ranch in Idaho, and by 11 he was working in the kitchen of a logging camp. The next year his family enrolled him in boarding school, where he learned dairy work. In his mid teens, he fled the school and became a mule team hand. For the next decade he drifted about the Northwest working as a teamster on reclamation and railroad projects, with intermittent stints in log- ging camps and sawmills. These experiences serve as the basis for Stevens’s two quasi-autobiographical novels, Brawnyman (1926) and Big Jim Turner (1948). The main character in each is named Jim Turner. Brawny and Jim are earnest, hardworking young men who spend their off-time drinking, fighting, gambling, and listening to tall tales in the bunkhouse. Despite their similarities, though, they are not the same character. The Jim Turner of Brawnyman is an innocent. At age 15, he longs to join “the tribe of working stiffs” and achieves his goal when he is made a wagon-greaser and ends his military career as a half-breed and half-bury. In 1922 he went to Portland to study law, but instead of studying, he worked along the waterfront. He went to Seattle in search of work, and there he met up with Joe Hill, the legendary IWW leader, who questioned his motives. From Portland to Spokane, small to cattle ranch, Jim faces a world in turmoil, in which the personal and political are deeply entwined. He is aided in his struggle by poetry, quoting Walt Whitman and referring to himself as “half poet and half bury.” Stevens eventually published secured his first recognition as a writer. He began publishing them in Stars and Stripes while still in the army, while living in Tacoma, he wrote and published Paul Bunyan (1924), a collection inspired by the tales he first heard in Northwest log- ging camps and later researched in the up- per Midwest and Canada. In the tradition of such tales, he starts with the familiar premise—a giant lumberjack and his blue ox—and embellishes freely from there. The three volumes of Paul Bunyan tales Stevens eventually published secured his popularity during his lifetime. Today Stevens is remembered in Northwest literary history mainly for the literary manifesto Stana Rerum (1927) that he co-wrote with H. L. Davis, author of the Pulitzer Prize-winning novel The Honey in the Horn (1919). In Stana Rerum, Stevens and Davis condemn Northwest writing as “a vast quantity of bilge” and call for more authentic depictions of the region in the mode of realists such as Theodore Dreiser and Sinclair Lewis. In 1936, Stevens became public relations counsel for the West Coast Lumbermen’s Association, headquartered in Sea- attle, and held this position for more than two decades. Following World War II, he was active in the Keep Washington Green campaign, the Friends of the Seattle Public Library, and Seattle’s Plymouth Congregational Church. Remaining true to his earliest influences: the outdoors, literacy, and religion. He continued to believe in the spirit and fulfillment of work, arguing in a 1959 talk in Portland that the country needed to restore the worker’s “faith in nature, faith in the land, faith in himself as an individual” and faith in traditional American democracy as a way of life. The Fiction and Folklore of James Stevens By Peter Donahue Call for Nominations The Historical Society invites nominations for its annual awards recognizing excellence in advancing the field of history in Washington. The honors to be presented include: the David Douglas Award, Robert Cross Memel Medal, Governor’s Award for Excellence in Teaching History, and Peace and Friendship Award. Nominations are due May 15, 2017. For details about the awards and the nomination process, visit: www.Washingtonhistory.org/About/Awards or contact Susan Rohrer (360-586-0166, susan.rohrer@wshs.wa.gov). Sponsorship The conference is being presented in partnership with Eastern Washington University, Gonzaga University, Whitworth College, and the Northwest Museum of Arts and Culture. Additional Reading Interested in learning more about the topics covered in this issue? The sources listed here will get you started. WINTER 2016–17 COLUMBIA 29 Uncovering the buried history of the French-speaking Canadiens and Métis across North America. “Songs Upon the Rivers raises the curtain on a story waiting more than a century to be told. The authors force us to reexamine certain mythologies and theories that define American historiography.” Dean Louder, coauthor of French America: Mobility, Identity and Minority Experience Across the Continent PACIFIC NORTHWEST HISTORY AT ITS BEST—now just a click away! Become a Historical Society member or COLUMBIA subscriber today! Visit WashingtonHistory.org/Support/Membership. COLUMBIA back issues are available for purchase via our online store: shop.WashingtonHistory.org. KAMIAKIN COUNTRY Washington Territory in Turmoil 1855–1858 By Jo N. Miles A carefully researched and balanced account of Chief Kamiakin’s influence during Washington Territory’s war of 1855–1858. CAXTON PRESS (800) 657-6465 | www.caxonpress.com SQUADRON POSTERS are community-created designs that revive the World War II style propaganda posters. Think “Join the Air Corps!” but for today’s modern military! Our artwork features vintage-inspired canvas prints depicting famous aircraft, ships, and submarines! At Squadron Posters, we turn military bases into vintage themed travel posters that are “Man Cave Worthy and Spouse Approved!” Collect all your travels and tell your story! See our vast collection at SquadronPosters.com PACIFIC NORTHWEST HISTORY AT ITS BEST—now just a click away! Become a Historical Society member or COLUMBIA subscriber today! Visit WashingtonHistory.org/Support/Membership. COLUMBIA back issues are available for purchase via our online store: shop.WashingtonHistory.org MILITARY TRAVEL POSTERS SQUADRON POSTERS SQUADRONPOSTERS.COM Gorham Printing MAKERS OF HISTORY BOOKS FOR THE PACIFIC NORTHWEST 3718 Mahoney Drive, Centralia WA 98531 1-800-837-0970 Introducing Make History with Gorham Printing, a free new resource guide to help history writers design, print and market their books. Request a complimentary copy at: www.gorhamprinting.com/make-history Our History Book Marketing Program now includes order fulfillment services! HERITAGE CIRCLE DONORS (total gifts of $55,000 or more from November 29, 2015, to November 29, 2016) Extravagant Giving: Carol Anderson Anon John & Karen Arba John of Sally Barbie Buckley Barbara & William Barnett Laurel Berry Thomas Blanton The Brownfield Family SPECIAL GIVING (gifts of $1,000–$4,999 as of November 29, 2016) Musal Al-Mannarri of IWW loggers taking a break from the picket line at the Saginaw Wobblies in Elma Ralph Chaplin (1887–1961), a member of the Industrial Workers of the World (IWW, often referred to as Wobblies) and author of the labor anthem Solidarity Forever, donated his photograph to Washington State Historical Society’s collection. Besides being a union activist,创办者，和writer—and friends with such labor radicals as Mother Jones and “Big Bill” Haywood—he was a curator at the Washington State Historical Society. Sustaining Members ($500–$999) INSTITUTIONAL GIVING (as of November 29, 2016) Chairman’s Club Barbara & William Barnett Kathie & George Balch John of Sally Barbie Founder’s Club The Brownfield Family Coronado Community Don & Pat Carlin Tim Connors Peter & Kathleen Dorgan Bill Driskell & Samantha Dean Stacy O’Malley Patron Level Anonymous Tim of Elma John & Karen Arba Tim Connors Peter & Kathleen Dorgan Bill Driskell & Samantha Dean Stacy O’Malley MEMBERS (as of November 29, 2016) Business Members ($250 and below) Benefactor Members ($250 and below) Bill of Carol Barnett Michael of Kristin Barnett Eric of Marianne Bean Donald of Greg Campbell Scott of Mary Chapman Michael of Fred Cooper William of Neil Douglas Prudence of Gabriel Drew Mark of Edward Mack John of David Maloney Mike of Jan Oyler John of Larry Olson For all the cruelty and hardship of our world, we are not mere prisoners of fate. Our actions matter and can bend history in the direction of justice.” —Barack Obama To donate or request anegus of regional historical interest to the Washington State Historical Society’s photograph collection, please contact Ed Hobbs, special collections curator (253-798-5177 or edhobbs@wsu.edu). To purchase a photo reproduction of an image in the society’s collections, visit Washingtonhistory.org and click on research; then collections. STEINS VINES & Grinds Washington’s Story of Beer, Wine & Coffee JANUARY 21–APRIL 23, 2017 Steins, Vines & Grinds is sponsored in part by Chateau Ste Michelle. 1911 Pacific Ave., Downtown Tacoma | www.WashingtonHistory.org | 1-888-BE-THERE
High-resolution melt (HRM) analysis for detection of SNPs associated with pyrethroid resistance in the southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) Guilherme M. Klafke Robert J. Miller Jason P. Tidwell USDA Donald B. Thomas USDA Daniela Sanchez The University of Texas Rio Grande Valley See next page for additional authors Follow this and additional works at: https://scholarworks.utrgv.edu/bio_fac Part of the Animal Sciences Commons, and the Biology Commons Recommended Citation This Article is brought to you for free and open access by the College of Sciences at ScholarWorks @ UTRGV. It has been accepted for inclusion in Biology Faculty Publications and Presentations by an authorized administrator of ScholarWorks @ UTRGV. For more information, please contact justin.white@utrgv.edu, william.flores01@utrgv.edu. Authors Guilherme M. Klafke, Robert J. Miller, Jason P. Tidwell, Donald B. Thomas, Daniela Sanchez, Teresa Patricia Feria-Arroyo, and Adalberto A. Perez de Leon High-resolution melt (HRM) analysis for detection of SNPs associated with pyrethroid resistance in the southern cattle fever tick, *Rhipicephalus (Boophilus) microplus* (Acari: Ixodidae)*☆* Guilherme M. Klaflake, Robert J. Miller, Jason P. Tidwell, Donald B. Thomas, Daniela Sanchez, Teresa P. Feria Arroyo, Adalberto A. Pérez de León *Institute of Pesquisas Veterinárias Desidério Finamor, Secretaria da Agricultura, Pecuária e Irrigação, Estrada do Conde 6000, Eldorado do Sul, RS, 92990-000, Brazil *United States Department of Agriculture, Agricultural Research Service, Cattle Fever Tick Research Laboratory, 22675 North Moore Rd, MAB 6419, Edinburg, TX, 78541, USA **Corresponding author. USDA-ARS-KBUSLIRL, 2700 Fredericksburg Road, Kerrville, TX, 78028, USA. **Corresponding author. IPVDF-SEAPI, Estrada do Conde 6000, Eldorado do Sul, RS, 92990-000, Brazil. Note: Nucleotide sequence data reported in this paper are available in the GenBank™ database under the accession numbers: MH986340, MH986341, MH986342, MH986343. **E-mail addresses:** guilherme-klaflke@agricultura.rs.gov.br (G.M. Klafke), beto.perezdeleon@ars.usda.gov (A.A. Pérez de León). https://doi.org/10.1016/j.ijpddr.2019.03.001 Received 1 October 2018; Received in revised form 27 February 2019; Accepted 4 March 2019 Available online 13 March 2019 Available online 13 March 2019 2211-3207/ © 2019 The Authors. Published by Elsevier Ltd on behalf of Australian Society for Parasitology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/). 1. Introduction Ticks infesting cattle and other farm animals in tropical and subtropical areas of the world are controlled primarily through the use of products containing synthetic acaricides. Resistance to one or more classes of acaricides, including pyrethroids, has been reported among... populations of the southern cattle fever tick, *Rhipicephalus (Boophilus) microplus* (Canestrini), which is considered the most economically important ectoparasite of livestock in parts of the world where it is endemic (Grisi et al., 2014; Rodriguez Vivas et al., 2017). *R. microplus* is also of veterinary relevance because it is a vector of the pathogens that cause bovine babesiosis, anaplasmosis and spirochaetosis (Aubry and Geale, 2011; Pérez de León et al., 2014; Walker et al., 2003). The characterization of pyrethroid resistance in *R. microplus* and other arthropod pests has been extensively explored (Rinkevich et al., 2012; Lovis et al., 2012; Nogueira Domingues et al., 2012; Kumar et al., 2013; Robbertse et al., 2016; Wyk et al., 2016; Bandara and Karunaratne, 2017; Sungirai et al., 2018). In addition to target site insensitivity, other mechanisms involved in pyrethroid resistance among *R. microplus* populations include detoxification enzymes such as esterases (Guerrero et al., 2002; Morgan et al., 2009; Rosario-Cruz et al., 2009; Aguirre et al., 2010; Jonsson et al., 2010; Rodriguez-Vivas et al., 2012; Lovis et al., 2012; Nogueira Domingues et al., 2012; Kumar et al., 2013; Robbertse et al., 2016; Wyk et al., 2016; Bandara and Karunaratne, 2017; Sungirai et al., 2018). In addition to target site insensitivity, other mechanisms involved in pyrethroid resistance among *R. microplus* populations include detoxification enzymes such as esterases (Guerrero et al., 2002; Singh and Rath, 2014; Gupta et al., 2016; Gaur et al., 2017), and monooxygenases (Graham et al., 2016). Bioassays like the larval packet test (Stone and Haydock (1962)), or the adult immersion test (Drummond et al., 1973) are used extensively to detect acaricide resistance phenotypes. These functional bioassays can discriminate the levels of resistance between tick populations and can be adapted to investigate possible mechanisms of resistance (Li et al., 2003). However, these bioassays require access to abundant numbers of viable engorged females that need to be collected, maintained for lengthy periods of oviposition and testing of viable larvae. Often, this can be difficult to achieve especially in areas of low infestation levels or where strict tick control measures are practiced. Molecular methods to detect acaricide resistance can be performed with few ticks, including samples of properly conserved dead ticks (e.g. in ethanol or isopropanol). The first description of an allele-specific polymerase chain reaction (AS-PCR) assay to genotype pyrethroid resistant tick strains was reported by Guerrero et al. (2001). This AS-PCR assay detects a mutation in domain III (T2134A) and was applied to studies on the epidemiology of pyrethroid resistance in *R. microplus* from Mexico (Guerrero et al., 2002; Rosario-Cruz et al., 2009; Rodriguez-Vivas et al., 2012). Lovis et al. (2012) proposed a multiplex AS-PCR, aimed to detect three (C190A; G215T and T2134A) single nucleotide polymorphisms (SNPs) in the *para*-sodium channel gene. More refined techniques were also developed, as a ‘Taqman’ dual probe quantitative PCR diagnostic assay to detect the C190A mutation (Morgan et al., 2009), and a melt analysis of mismatch amplification mutation assay (melt-MAMA) qPCR platform, designed to detect the mutations T170C, C190A, and T2134A (Stone et al., 2014). High-resolution melt analysis (HRM) is a closed-tube post-PCR analysis involving the use of a dye that fluoresces when intercalated with double-stranded DNA (dsDNA), but not when in solution in the absence of DNA (Reed et al., 2007). The intercalated dye is released when dsDNA denatures, resulting in a loss of fluorescence at the melting transition of the PCR product. HRM curves are generated by measuring the decrease of fluorescence as the temperature is slowly increased with a high level of accuracy (0.05–0.1 °C). The fluorescence decreases at each step due to the transition of the DNA from double-to-single-stranded. The melting temperature of a DNA molecule is determined by its nucleic acid sequence and length (Reed et al., 2007). Differences in these nucleotide sequences between samples result in melting profiles that are unique to particular genotypes, allowing for differentiation. A PCR reaction that contains only one type of DNA sequence, such as homozygous templates from diploid organisms, produces a melt curve with one peak. Heterozygous templates result in a mixture of homopolymers and heteropolymers. Due to the imperfect binding of their strands, the melting temperature is strongly lowered in the heteropolymers, resulting in an early peak in the curve. Multi-loci SNP products will cause more complex heteropolymer formations and additional peaks in the melt curves (Mader et al., 2008). HRM was successfully used to detect pyrethroid resistance mutations in the yellow fever mosquito *Aedes aegypti* (Wulidiandi et al., 2015), and in the scabies mite *Sarcoptes scabiei* (Passay et al., 2008). In a direct comparison with other techniques (i.e. AS-PCR and Taqman probes) the HRM had excellent performance in detecting knock down resistance (kdr) mutations in previously sequenced *Anopheles gambiae* standard samples. However, when the technique was used to detect those mutations in field derived samples with variable quantity and quality of DNA, its performance was not as efficient as the Taqman probes. Nevertheless, the cost of the analysis per sample was lower than the other two techniques (Bass et al., 2007). Here, we developed an HRM assay to simultaneously detect multiple mutations in the *para*-sodium channel gene associated with pyrethroid-resistant *Rhipicephalus microplus*. Reference laboratory tick strains from Mexico, Brazil and USA, as well as field samples from Mexico were used in this study. 2. Materials and methods 2.1. Ticks Colonies of *R. microplus* maintained at the USDA-ARS Cattle Fever Research Laboratory (CFTRL) in Edinburg, Texas were used in this study and were reared as described by Davey et al. (1980). The Deutch strain served as the acaricide susceptible reference collected originally in Laredo, Texas and maintained as a colony at the CFTRL since 2001. Deutch strain ticks from the *F*$_{58}$ generation were used in this study. Santa Luiza is the colony that includes ticks resistant to permethrin and amitraz, which were collected from a ranch in Rio Grande do Sul, Brazil; this colony was maintained at the Mexican National Parasitology Laboratory, Juítepeú, Morelos, Mexico, before being established at the CFTRL in 2000 (Li et al., 2004). Ticks from the *F*$_{64}$ generation of the Santa Luiza colony were used. Ticks from the El Zamora colony are resistant to permethrin, amitraz, and fipronil, and were collected in 2010 from a ranch in the State of Tamaulipas, Mexico (Miller et al., 2013). *F*$_{52}$ generation of El Zamora ticks were used. Ticks to establish the Yucatan colony were collected in 2014 from red deer (*Cervus elaphus*) at a ranch located in the State of Yucatan, Mexico (Rodríguez-Vivas et al., 2014), and are resistant to cypermethrin, coumaphos, and ivermectin. Ticks of the El Zamora *F*$_{17}$ generation were used. *Rhipicephalus microplus* field samples were obtained from cattle during inspections at the United States Ports-of-Entry located at the border of Mexico and the State of Texas. Ticks were received at the CFTRL inside 5 mL plastic assay tubes and were stored in cryovials and immediately frozen at −80 °C to be used in the molecular analysis. In total, 29 semi-engorged females were processed and those were taken from cattle with origins in different states of Mexico: Coahuila (n = 3); Nuevo León (n = 7); Tamaulipas (n = 14) and Veracruz (n = 5). No previous information about the pyrethroid resistance status was obtained from those ticks. 2.2. Preparation of ticks Engorged female *R. microplus* from the susceptible (Deutch), and resistant colonies (Santa Luiza, El Zamora, and Yucatan) were collected after their natural detachment from cattle according to the protocol approved by the Institutional Animal Care and Use Committee. After collection, the ticks were washed with water and dried with paper towels. From each colony, 30 engorged females were incubated in an environmental chamber at 28 °C, and a relative humidity of 92% in a plastic petri dish (9 cm diameter) for 20 days to allow egg laying (Davey et al., 1980). Depleted females were separated from the eggs, washed with distilled water, dried with paper towels and individually frozen at – 80 °C to be used in the molecular analysis. The eggs were mixed thoroughly and incubated under the same conditions in 2-dram glass vials closed with cotton plugs to allow the passage of air and moisture to permit larval hatching. The egg masses were checked daily for larval hatching. Larvae 14–21 days old were used in the bioassays. 2.3. Bioassays The bioassays were performed with analytical standards of the following chemicals: permethrin (FMC, Philadelphia, PA, USA), cypermethrin, deltamethrin, and flumethrin (Sigma Aldrich Co., St. Louis, MO, USA). In order to characterize the phenotypic resistance to these chemicals, the larval packet test procedure was used with pre-established discriminating doses (DDs) calculated as $2 \times \text{LC}_{95}$ of a susceptible reference strain. The DDs were 0.25% permethrin (Miller et al., 1999), 0.20% cypermethrin, 0.06% deltamethrin, and 0.01% flumethrin (FAO, 2004). Acaricides were diluted in a mixture containing two parts of trichloroethylene and one-part olive oil (TCH£-OO) in order to prepare the impregnation solutions. A volume of 0.67 mL of each acaricide solution was used to impregnate a piece of quantitative filter paper (85 mm × 75 mm – Whatman No. 256, Whatman Inc., Maidstone, England). The material was left to dry for 2 h inside a fume hood to allow for trichloroethylene evaporation. After drying, packets were placed on top, and incubated at 27 ± 1 °C and 80% relative humidity. On the day of testing, filter papers were taken from the refrigerator, folded in the middle, and sealed on both sides with metal clips to form the packets. Approximately 100 tick larvae were transferred to each packet using a flat paintbrush. The packets were sealed with a third clip on top, and incubated at 27 ± 1 °C and 80–90% relative humidity. Control groups were exposed to filter papers impregnated with acaricide-free TCH£-OO. After 24 h, larval mortality was determined by counting the total number of dead and viable individuals. Larvae that were paralyzed or moving only their appendices without the ability to walk were considered non-viable. Three packets impregnated with each acaricide as well as controls were prepared for each tick sample, i.e. from the Deutch, Santa Luiza, El Zamora, and Yucatan colonies. Percentage of larval mortality was determined for each of the three packets of each acaricide treatment. For each test, mean mortality and standard errors were calculated with Microsoft Excel (Microsoft Corporation, Redmond, WA). The knockdown effect of permethrin was assessed with a lethal time bioassay. About 100–150 larvae of each strain were incubated inside the filter paper packets impregnated with 0.25% permethrin as described above. The mortality was determined at six time points: 10, 20, 30, 40, 50, and 60 min after the exposure, as described for the resistance test above. Mortality data were analyzed using the Probit model in the Polo Plus software (Version 1.0, licensed. LeOra Software, 2003). For each test, the following parameters were determined: median lethal time (LT50), with its respective 95% confidence limits (95% CL), and the slope of the regression line. The resistance ratios (RR) were obtained using the Polo-Plus software employing the formula described by Robertson et al. (2007). Comparisons were determined to be significant when the calculated 95% CL did not overlap. For visualization of data, the log time vs. probit converted mortality plots were generated using Microsoft Excel (Microsoft Corporation, Redmond, WA). 2.4. DNA extraction The genomic DNA of ticks was extracted using a phenol-chloroform method. Frozen ticks were taken from ultracold freezer (– 80 °C) and transferred to 2-mL plastic tubes containing five ceramic beads (2.8 mm diameter - Omni International, Kennesaw, GA, USA) each. The tubes also contained 600 μL of lysis buffer (10 mM Tris-HCl pH 8; 2 mM EDTA pH 8; 0.5% SDS), 3 μL proteinase K (20 mg/mL, Invitrogen, Carlsbad, CA, USA), and were processed at 4000 rpm for 15 s with a bead mill homogenizer (Omni International, Kennesaw, GA, USA). Homogenates were incubated for 12–18 h at 55 °C to allow for protein digestion. Following, the samples were incubated at 65 °C for 15 min to inactivate the proteinase K. After briefly cooling in an ice bath, 5 μL of RNase A (20 mg/mL, Invitrogen, Carlsbad, CA, USA) was added to the homogenates followed by incubation at 37 °C for 15 min to remove RNA contamination. The homogenates were submitted to a phenol-chloroform DNA extraction procedure. The DNA was precipitated in an ice-cold absolute ethanol and sodium acetate solution at −20 °C for 12–18 h. The DNA pellets were collected by centrifugation (10,000 g at 4 °C for 15 min) and washed twice with 70% ethanol. The final pellet was suspended in 50 μL Tris-EDTA, pH 8. The genomic DNA was quantified on an EON spectrophotometer (Biotek, Winooski, VT, USA), and diluted to 100 ng/μL for PCR. 2.5. PCR and sequencing In order to identify the mutations, we used primers designed to amplify the exon region of the para-sodium channel gene domain II S4–S5 linker and the exon region of the domain III S6. The identification of the SNPs present in domains II and III was obtained by Sanger dyeoxy sequencing. Sequences of the exon encoding domain II were obtained from DNA fragments amplified with the primers designed by Morgan et al. (2009) where the forward BmNaF5 (5’TACGTGGTTGTCAAGCTAGC) and reverse primer BmNaR5 (5’ACTTCTTTGGTATCTTGC) yielded a 167 bp product. PCRs were carried out in 50 μL volumes containing the following reagents: 100 ng of DNA template, 1 × PCR buffer, 1.5 mM MgCl2, 0.2 mM dNTPs, 200 nM each primer and 1 U of AmpliTaq Gold II polymerase (Applied Biosystems, Carlsbad, CA, USA). The reaction was performed under the following conditions: 95 °C for 5 min, followed by 40 cycles of 95 °C for 30 s, 50 °C for 30 s, 72 °C for 30 s, and a final extension step of 72 °C for 7 min and final hold at 4 °C. Sequences of the exon encoding domain III were obtained from DNA fragments amplified with the primers described by Stone et al. (2014). Initially a 135 bp fragment was amplified using the forward primer RmNaDomainIII5F1 (5’AACAGGGACCAACCAGGATAGC) and reverse primer RmNaDomainIII5R2 (5’TTCTCTTTGTTCACTTGAAT TGT). PCRs were carried out in 10 μL volumes containing 100 ng of DNA template, 1 × PCR buffer, 2.5 mM MgCl2, 0.2 mM dNTPs, 1 U of AmpliTaq Gold II polymerase. The reaction was performed under the following conditions: 95 °C for 10 min, followed by 40 cycles of 94 °C for 60 s, 53 °C for 30 s, 72 °C for 30 s. The PCR products from this first reaction were diluted 1:1000 and used as the template for a second PCR using tailed primers. The second PCR used forward tailed primer RmNaDomainIII5F (5’ACACCAATGAAGACAGAACACCGGAAT ACG) and reverse tailed primer RmNaDomainIII5R (5’ACACCATGTCGTTGACTTTTGGTATCTTGC) resulting in an amplicon length of 173 bp. The conditions of the second PCR were identical to the first, with exception of the annealing temperature that was 65 °C. PCR products were visualized by electrophoresis on 2.2% agarose FlashGel DNA cassettes with a FlashGel System (Lonza Rockland, Inc., Rockland, ME, USA). PCR products were purified using Diffinity RapidTIp® (Chiral Technologies, Inc., West Chester, PA, USA) and sequenced using the primers BmNaF5 and BmNaR5 for the domain II amplicons and tail primers RmNaDomainIII5F3eq (5’ACACCAATGAAGACAGAACACCGGAATACG) and RmNaDomainIII5R3eq (5’ACACCATGTCGTTGACTTTTGGTATCTTGC) for amplification through capillary electrophoresis in a 96-capillary Applied Biosystems 3730xl DNA Analyzer (Retrogen, Inc.). The validation of the allele sequences for heterozygous individuals was performed by cloning and sequencing of PCR amplicons. PCR products were ligated into the pJET 1.2/blunt vector of the CloneJET PCR Cloning Kit (Thermo Fisher Scientific, Waltham, MA, USA) according to the manufacturer’s specifications. Ligations were used to transform DH5α competent cells (Invitrogen, Carlsbad, CA, USA). Up to eight colonies per individual tick were selected for PCR screening with the pJET1.2 plasmid primers. Six clones containing the correct insert size were chosen for sequencing according to the methods described above using pJET1.2 primers. Sequencing data were aligned and translated with CLC Main Workbench 7 (Qiagen Aarhus A/S, Copenhagen, Denmark). Sequences were compared to each other and analyzed for the presence of the different SNPs. 2.6. Detection of domain III mutation Previously described AS-PCR technique was used to genotype the ticks for the T2134A mutation (Guerrero et al., 2001, 2002). PCR was performed using 20µL reactions containing the following reagents: 100 ng of DNA template, 1 x PCR buffer, 1.75 mM MgCl2, 0.2 mM dNTPs, 100 nM each primer and 0.5 U AmpliTaq Gold II polymerase (Applied Biosystems, Carlsbad, CA, USA). The reactions were carried out in a thermocycler programmed for 96 °C for 2 min followed by 37 cycles, each consisting of denaturation at 94 °C for 1 min, annealing at 60 °C for 1 min, and extension at 72 °C for 1 min. The program also included a final extension step at 72 °C for 7 min. PCR products were visualized by electrophoresis on 2.2% agarose as described above. 2.7. Quantitative PCR - HRM assays Two high-resolution melt (HRM) assays were developed to genotype the different pyrethroid resistance related polymorphisms in the para-sodium channel gene of *R. microplus*. PCR primers were designed using PRIMER3WEB v.4.0.0 (Untergasser et al., 2012). The first assay targeted the Domain II S4–S5 mutations, and the primers were designed to flank the following nucleotide substitutions: T170C, G184C, C189A (silent), C190A and G215T. Reactions with the forward primer flanked the following nucleotide substitutions: T170C, G184C, C189A (silent), C190A and G215T. Reactions with the forward primer flanked the following nucleotide substitutions: T170C, G184C, C189A, and C190A. The substitutions G184C and C190A resulted in amino acid changes (G62R and L64I, respectively) and C189A was a silent substitution. The second assay targeted the Domain III S6 mutation T2134A. Primers used on the reactions were HRM_Rm_Na-D2_Fw (5′CATGTGGTCCCTACCTTA) and the reverse primer HRM_Rm_Na-D2_Rv (5′GATCCCGGACAAAGTCA) yielded an 88 bp amplicon. Sequencing of the products was performed using the pJET1.2 plasmid primers. Six clones containing the correct insert size were chosen for sequencing according to the methods described above using pJET1.2 primers. Sequencing data were aligned and translated with CLC Main Workbench 7 (Qiagen Aarhus A/S, Copenhagen, Denmark). Sequences were compared to each other and analyzed for the presence of the different SNPs. The HRM assay was successfully used to determine the presence of previously described AS-PCR technique was used to genotype the ticks for the T2134A mutation (Guerrero et al., 2001, 2002). PCR was performed using 20µL reactions containing the following reagents: 100 ng of DNA template, 1 x PCR buffer, 1.75 mM MgCl2, 0.2 mM dNTPs, 100 nM each primer and 0.5 U AmpliTaq Gold II polymerase (Applied Biosystems, Carlsbad, CA, USA). The reactions were carried out in a thermocycler programmed for 96 °C for 2 min followed by 37 cycles, each consisting of denaturation at 94 °C for 1 min, annealing at 60 °C for 1 min, and extension at 72 °C for 1 min. The program also included a final extension step at 72 °C for 7 min. PCR products were visualized by electrophoresis on 2.2% agarose as described above. 2.7. Quantitative PCR - HRM assays Two high-resolution melt (HRM) assays were developed to genotype the different pyrethroid resistance related polymorphisms in the para-sodium channel gene of *R. microplus*. PCR primers were designed using PRIMER3WEB v.4.0.0 (Untergasser et al., 2012). The first assay targeted the Domain II S4–S5 mutations, and the primers were designed to flank the following nucleotide substitutions: T170C, G184C, C189A (silent), C190A and G215T. Reactions with the forward primer flanked the following nucleotide substitutions: T170C, G184C, C189A, and C190A. The substitutions G184C and C190A resulted in amino acid changes (G62R and L64I, respectively) and C189A was a silent substitution. The second assay targeted the Domain III S6 mutation T2134A. Primers used on the reactions were HRM_Rm_Na-D2_Fw (5′CATGTGGTCCCTACCTTA) and the reverse primer HRM_Rm_Na-D2_Rv (5′GATCCCGGACAAAGTCA) yielded an 88 bp amplicon. Sequencing of the products was performed using the pJET1.2 plasmid primers. Six clones containing the correct insert size were chosen for sequencing according to the methods described above using pJET1.2 primers. Sequencing data were aligned and translated with CLC Main Workbench 7 (Qiagen Aarhus A/S, Copenhagen, Denmark). Sequences were compared to each other and analyzed for the presence of the different SNPs. The HRM assay was successfully used to determine the presence of previously described pyrethroid resistant SNPs in two regions of the para-sodium channel gene of *R. microplus* (domain II S4–S5 and domain III S6). In domain II, three SNPs were found among individuals of the *R. microplus* strain were dead. For the Santa Luiza resistant strain, the calculated LT50 was 65.02 (95% CL = 53.99–86.51), which is significantly higher than for the Deutch strain. It was not possible to calculate the LT50 for the El Zamora and Yucatan strains, as the observed mortality were found to be at very low rates (~5%) across the observed data points (Fig. 1), supporting the “knockdown” resistance phenotype observed for both of these strains. 3. Results 3.1. Pyrethroid resistance The larval packet discriminating dose bioassays confirmed the pyrethroid resistance phenotype of the analyzed strains. Table 1 presents the mortality data of each strain against permethrin, cypermethrin, deltamethrin and flumethrin. A high level of resistance was observed for El Zamora and Yucatan strains, across all the pyrethroids tested. The Santa Luiza strain showed to be less resistant than the other two, with approximately half of the tick larvae surviving to the discriminating dose after 24 h. All the larvae from the susceptible reference strain died after exposure to the acaricides tested. Fig. 1 and Table 2 shows the results of the lethal time bioassay with permethrin carried out with the four strains. The median lethal time (LT50) for Deutch was 21.74 min (95% CL = 18.48–24.63). After 40 min of exposure, approximately 95% of the larvae of the susceptible strain were dead. For the Santa Luiza resistant strain, the calculated LT50 was 65.02 (95% CL = 53.99–86.51), which is significantly higher than for the Deutch strain. It was not possible to calculate the LT50 for the El Zamora and Yucatan strains, as the observed mortality were found to be at very low rates (~5%) across the observed data points (Fig. 1), supporting the “knockdown” resistance phenotype observed for both of these strains. 3.2. HRM genotyping of reference strains The HRM assay was successfully used to determine the presence of previously described pyrethroid resistant SNPs in two regions of the para-sodium channel gene of *R. microplus* (domain II S4–S5 and domain III S6). In domain II, three SNPs were found among individuals of the tick colonies and were validated by cloning and sequencing: G184C, C189A, and C190A. The substitutions G184C and C190A resulted in amino acid changes (G62R and L64I, respectively) and C189A was a silent mutation (Fig. 2). In domain III, we detected, both by PCR-HRM and AS-PCR, the mutation T2134A that results in a Phe to Ile change at the amino acid residue 712 of the para-sodium channel. The SNPs T170C and G215T were not detected with the HRM assay or sequencing the pJET1.2 plasmid primers. Six clones containing the correct insert size were chosen for sequencing according to the methods described above using pJET1.2 primers. Sequencing data were aligned and translated with CLC Main Workbench 7 (Qiagen Aarhus A/S, Copenhagen, Denmark). Sequences were compared to each other and analyzed for the presence of the different SNPs. Table 1 presents the mortality data of each strain against permethrin, cypermethrin, deltamethrin and flumethrin. <table> <thead> <tr> <th>Strain</th> <th>Mean percentage of mortality after 24 h (standard deviation)</th> </tr> </thead> <tbody> <tr> <td></td> <td>Permethrin</td> </tr> <tr> <td>Deutch</td> <td>100 (0)</td> </tr> <tr> <td>Santa Luiza</td> <td>59.15 (3.53)</td> </tr> <tr> <td>El Zamora</td> <td>28.12 (3.77)</td> </tr> <tr> <td>Yucatan</td> <td>2.85 (2.35)</td> </tr> </tbody> </table> Figs. 3–5 show the normalized and difference melt plots of the fragments amplified by qPCR. On domain II, eight genotypes could be identified among the laboratory strains. All the ticks from the susceptible reference strain Deutch presented the same genotype (wt), with no substitutions of nucleotides in comparison to the reference sequence (GenBank: AP134216). The C190A and G184C substitutions were found to be associated with both homozygous and heterozygous alleles (Fig. 3A–D). The substitution in nucleotide 189 was found only in heterozygosity and always associated with C190A (Fig. 5A). The occurrence of G184C and C190A was also found among the tick samples, only in heterozygosity (Fig. 5A). On domain III, three genotypes were detected among the laboratory strains: wild type, heterozygous (T2134W), and homozygous (T2134A) (Fig. 4A and B), and the genotypes were confirmed with the AS-PCR technique and sequencing (Fig. 2B). The designed HRM assay showed versatility in detecting a number of different genotypes. With two reactions (aimed at domains II and III), we were able to detect and assign six different genotypes (Table 3). One genotype was associated with the susceptible wild-type, and five associated with pyrethroid resistance. Among the individuals of the El Zamora strain, the only detected mutation was the C190A, with 75% of the ticks being homozygous for this mutation and 25% heterozygous; no wild types were detected. Half of the sampled population (n = 12) presented the C189A silent mutation, always combined with the nucleotide substitution at position 190. All the Yucatan ticks were homozygous for the resistant mutations at domains II (G184C) and III (T2134A) simultaneously. Ticks from the Santa Luiza strain presented the three SNPs and all the possible genotypes associated with resistance. Most of the Santa Luiza ticks (82.6%) carried at least one resistant allele with a low frequency of resistant homozygous ticks (8.7% for G184C/T2134A and C190A). Five ticks (21.7%) presented the three mutant loci simultaneously. To the best of our knowledge this is the first description of the existence of three simultaneous mutations in the para-sodium channel gene of R. microplus. A good phenotype-genotype correlation of the assays was observed. Pearson Product Moment correlation analysis and linear regression analyses were carried out (Sigma Plot 11.0, Systat Software, 2008) by plotting the frequency of ticks carrying any of the mutations in homozygosis (GG/II/FF and RR/LL/II) against the survivorship in the bioassays with all the pyrethroids tested (Fig. 6). In a Pearson Product Moment correlation analysis, with the exception of cypermethrin (r = 0.945; p = 0.0552), there was a significant correlation between resistant-homozygous ticks (RR) and the survivorship after exposure to permethrin (r = 0.964; p = 0.0361), deltamethrin (r = 0.964; p = 0.0363), and flumethrin (r = 0.969; p = 0.0311). This observation was coherent with the results from the bioassays, showing a broad spectrum of resistance against the different pyrethroid acaricides tested (Tables 1 and 2). The high frequency of homozygous resistant ticks in the El Zamora and Yucatan strains was compatible with the “knockdown-resistance” phenotype observed in the lethal-time bioassays (Table 2, Fig. 1). This observation confirmed the association of mutations in the para-sodium channel with resistance to synthetic pyrethroids. ### 3.3. HRM genotyping of field samples The developed technique was used with DNA from R. microplus field samples from northern states of Mexico (Supplementary table). The HRM was successful in detecting the previously described mutations associated with pyrethroid resistance in the tick colonies (e.g. G184C; C190A and T2134A). Three ticks were wild type for all the loci and can be considered susceptible. Two ticks presented one allele with the G215T mutation, combined with either the T170C or the C190A SNPs. Fig. 2. Nucleotide sequence alignment of sodium channel domains II (2A) and III (2B) DNA fragments of *R. microplus* reference sequence (GenBank Accession Number AF134216) with its respective translated amino acid sequences, and clone sequences obtained from pyrethroid resistant ticks: T170C, G184C, C190A, G184C_C190A, C189A_C190A, C190A_G215T, T170C_G215T, T170C_C189A_C190A, T2134A, T2134A_C2136A, C2130T_T2134A, and C2136A. Identical nucleotides are marked with dots. Numbers above sequences are based on the *R. microplus* para-sodium channel. Sequencing primers positions (Domain II: BmNa5F and BmNa5F; Domain III: RmNaDomainIIIF1 and RmNaDomainIIIRS2-CON) are identified as gray arrows. HRM primers (Domain II: HRM_Rm_Na-D2_F2 and HRM_Rm_Na_D2_F2; Domain III: HRM_Rm_Na_F and HRM_RmNa_F) are identified in black. Replaced amino acid residues are identified in red with one asterisk. The synonymous substitutions are identified in orange with two asterisks. This is the first detection of the G215T in the Neotropical region. This SNP results in a Gly to a Val change at the amino acid residue 72 in the domain II (Fig. 2A). A novel SNP, C2136A, was detected with the HRM in the domain III (Fig. 4C and D) resulting in a Phe to Leu change in the position 712. When this mutation simultaneously occurs with the T2134A mutation (Fig. 5D), the amino acid change was Phe to Ile (Fig. 2B). Seven ticks carry the C2136A mutation, two in homozygosis, and always associated with mutations in the domain II (T170C and C190A). One tick was heterozygous for a silent mutation, C2130T, that was detected in association with T170C, G215T and C2136A (Fig. 2). Ten ticks presented both G184C and T2134A SNPs simultaneously. Nine ticks carry at least one C190A allele, six in homozygosis. The HRM allowed the detection of the T170C (Fig. 3G and H), that results in a Met to a Thr change at the amino acid residue 57 in the domain II of the \( \text{para} \)-sodium channel gene of \( R. \ microplus \). The domain II (Fig. 2A). A novel SNP, C2136A, was detected with the HRM in the domain III (Fig. 4C and D) resulting in a Phe to Leu change in the position 712. When this mutation simultaneously occurs with the T2134A mutation (Fig. 5D), the amino acid change was Phe to Ile (Fig. 2B). Seven ticks carry the C2136A mutation, two in homozygosis, and always associated with mutations in the domain II (T170C and C190A). One tick was heterozygous for a silent mutation, C2130T, that was detected in association with T170C, G215T and C2136A (Fig. 2). Ten ticks presented both G184C and T2134A SNPs simultaneously. Nine ticks carry at least one C190A allele, six in homozygosis. The HRM allowed the detection of the T170C (Fig. 3G and H), that results in a Met to a Thr change at the amino acid residue 57 in the domain II of the \( \text{para} \)-sodium channel gene (Fig. 2A). Three ticks homozygous for this mutation and one was heterozygous. Two ticks carry this mutation associated with the synonymous SNP C189A and the mutation C190A simultaneously (Fig. 5C). The more part of the ticks presented one (41%) or two mutant loci (31%) in the para-sodium channel. Two ticks presented three SNPs and three ticks presented four SNPs at the same time. The most frequent SNP was the C190A, found in 44.8% of the ticks, followed by T2134A, found in 37.9% of the samples. All the previously known and novel mutations in the para-sodium channel were detected in single ticks with two HRM reactions, aimed at the domains II and III (Figs. 3–5). 4. Discussion Target site insensitivity is a resistance mechanism in *R. microplus* against pyrethroid acaricides, which is conferred by one or more mutations present in the target site, the para-sodium channel (Guerrero et al., 2014). Based on the results presented here, we successfully developed two qPCR-HRM assays to genotype the G184C, C190A and T2134A mutations, associated with resistance against four compounds of the synthetic pyrethroid class of acaricides: permethrin, cypermethrin, deltamethrin and flumethrin. We were also able to detect multiple mutations and their different combinations in two side-by-side reactions (domains II and III). Genotyping of mutations directly related to acaricide resistance could provide a useful surveillance tool to monitor resistance status promptly and accurately among *R. microplus* populations. This approach could also help refine integrated tick management strategies by adapting the selection of acaricides for effective and rational *R. microplus* control based on resistance genetic data obtained in real time. In HRM analysis, a small region of DNA (70–100 bp) spanning the SNPs of interest is amplified by PCR in the presence of a dsDNA fluorescent dye (EVA green). This dye is used at a high concentration to achieve maximum saturation of the resulting dsDNA fragment (Bass et al., 2007). A high-resolution melt step using equipment with high thermal and optical precision is then performed in order to determine the melting temperature (Tm) of the amplicon. While the dsDNA dissociates into single strands, the dye is released and the fluorescence decreases giving a melt curve profile characteristic of the amplicon sequence (Liew et al., 2004). The C190A, T170C and C2136A mutations are predicted to cause a relatively large change in the Tm of the amplicon (Fig. 3A, G and 4C). In contrast, the G184C and the T2134A are predicted to cause a very small change in Tm in the melt curve making it more difficult to detect in the normalized curves (Figs. 3C and 4A). However, the observation of the differences in melt plots helps in distinguishing the genotypes (3D and 4B). The combinations of different mutations (C189A/C190A; C190A/G215T; T170C/G215T; T170C/C189A/C190A; T2134A/C2136C; C2130T/C2136T) are predicted to cause even larger variations in the Tm of the melt curves (Figs. 3A–5D). Using samples with known genotypes (as determined by sequencing) the developed assays were able to efficiently distinguish the different genotypes, in homozygosity and heterozygosity. The Santa Luiza strain has been studied by synergistic bioassays and genetic studies to determine its mechanisms of resistance to permethrin (Li et al. 2007, 2008). The present study clarifies the major mechanism... involved, which is the presence of one, two or three mutations in different amino acid residues of the para-sodium channel gene. Stone et al. (2014) made the first description of the presence of simultaneous mutations in the para-sodium channel gene in R. microplus populations from Mexico, where a combination of the M57T amino acid change with L64I or F712I was linked to high levels of pyrethroid resistance. Nevertheless, the mutations in the Santa Luiza ticks were mostly heterozygous (82.6%; Table 3). The cause for the lower resistance level in Santa Luiza is unknown when compared to the El Zamora and Yucatan strains. El Zamora ticks presented mutations at the nucleotide positions 189 and 190 (kdr). Twenty-five percent of the ticks were heterozygous for the C190A mutation, and the remaining were homozygous. The C189A substitution is synonymous and was never found by itself and always in heterozygosity. The same observation was made by Stone et al. (2014) in screening populations from Mexico and the USA. These authors pointed out that the presence of this SNP could prevent PCR amplification of fragments using specific primers designed to detect the C190A mutation. The HRM domain II assay we developed was successful in detecting both polymorphisms and no amplification failures were detected. The Yucatan strain was the most resistant strain evaluated in this study (mean mortality between 0 and 2.85% depending on the acaricide tested). All the ticks genotyped were homozygous for the G62R and F712I mutations, which can explain the low mortality levels found and the knockdown resistance phenotype observed (Table 2, Fig. 1). ![Graphs showing HRM assays for pyrethroid resistance with multiple mutations detected in the domains II and III of para-sodium channel gene of R. microplus.](image) **Fig. 5.** Fluorescence difference curves obtained with HRM assays for pyrethroid resistance with multiple mutations detected in the domains II and III of para-sodium channel gene of R. microplus. 5A: G184C_C190A, and C189A_C190A; 5B: C190A_G215T, and T170C_G215T; 5C: T170C_C189A_C190A; 5D: T2134A_C2136A and C2130T_C2136A. **Table 3** <table> <thead> <tr> <th>Genotype</th> <th>Amino acid sequence</th> <th>SNP</th> <th>Genotype frequency (%)</th> </tr> </thead> <tbody> <tr> <td></td> <td></td> <td></td> <td>G184C</td> </tr> <tr> <td>Wild type</td> <td>GG/LL/FF</td> <td>GG</td> <td>CC</td> </tr> <tr> <td>Heterozygous</td> <td>GG/LI/FF</td> <td>GG</td> <td>CA</td> </tr> <tr> <td></td> <td>GR/LI/FI</td> <td>GC</td> <td>CC</td> </tr> <tr> <td></td> <td>GR/LI/FI</td> <td>GC</td> <td>CA</td> </tr> <tr> <td>Homozygous</td> <td>GG/LI/FF</td> <td>GG</td> <td>AA</td> </tr> <tr> <td></td> <td>RR/LL/II</td> <td>CC</td> <td>CC</td> </tr> </tbody> </table> G: Glycine; L: Leucine; F: Phenylalanine; R: Arginine; I: Isoleucine; SNP: single-nucleotide polymorphism. This assay could also be used to mitigate the risk associated with acaricide-resistant *R. microplus* that may infest cattle presented at ports of entry by Mexico intended for export to the U.S. (González and Hernández, 2012). Among the ticks sampled at the USA Ports-of-Entry, we found a high frequency of individuals carrying mutations in para-sodium channel gene. Most of them, with C190A or T2134A and combinations of the different mutations. The presence of multiple mutations in the para-sodium channel gene is correlated with high levels of pyrethroid resistance, and here we found ticks carrying three or four SNPs in both domains II and III (Supplementary Table). More information is required about acaricide usage or resistance status of the field samples to determine if that correlation causes high levels of pyrethroid resistance as suggested by the results of the HRM analysis. Comparing different techniques for detection of knockdown resistance mutations in mosquitoes, Bass et al. (2007) observed that HRM analysis presented a higher failure rate than other assays, such as AS-PCR and ‘Taqman’ probes. The authors suggest that the quality and quantity of DNA could be affecting the amplification, preventing the attainment of a high signal plateau in the PCR phase, which could result in inconclusive or low resolution HRM data. In our experiments we were able to obtain satisfactory amplification and discrimination among genotypes from the tick colonies as well as from the field samples. The quality and quantity of DNA obtained with the phenol-chloroform purification was high (260/280 ratio ~1.8, over 200 ng/μL of dsDNA per sample), which likely had a positive impact on the quality of our amplification. The main advantage of the HRM, comparing to AS-PCR and Taqman is its capacity of screening different variants in a given gene that would be undetectable using allele specific probes and primers, as virtually any different nucleotide can be detected in a sequence using the high-resolution analysis of the melting temperatures of those fragments. This feature is particularly interesting to define samples to be analyzed by sequencing in SNP discovery studies. When investigating the field samples from Mexico, in most of the cases, we detected the previously known SNPs (C190A, 44.83%, and T2134A, 37.93%). However, we were able to detect novel melt curves (Fig. 3G, H, 4C, 4D, 5B, 5C, and 5D), indicating the existence of different genotypes that were later confirmed by cloning and sequencing. Using the screening approach, we were able to detect for the first time in the Neotropical region, the mutation G215T, associated with flumethrin resistance in Australia (Jonsson et al., 2010) and a novel SNP, C2136A, located in the same codon for the Phe at the position 712. However, when this mutation is present in the absence of the T2134A mutation, the amino acid is substituted for an Ile. We hypothesize that the physiological effect of this substitution is the same as the Phe to Leu, which results in resistance to pyrethroids (He et al., 1999). While there is no information about the phenotype of the different patterns of mutations regarding the susceptibility to pyrethroids among the field samples, further research is needed to test our hypothesis. This study provides a technique that can be used for the surveillance of pyrethroid resistance in *R. microplus* populations. Our findings can be used to develop a high-throughput method to genotype and detect allele-specific mutations in *R. microplus* populations that cause outbreaks in the U.S. The rapid turnaround of results based on a high-throughput HRM acaricide resistance assay could help Cattle Fever Tick Eradication Program personnel manage the response to *R. microplus* outbreaks, and also inform decisions regarding the concern with cattle presented at ports of entry by Mexico with the intention to be exported to the U.S. that may be infested with *R. microplus* resistant to acaricides (Pérez de León et al., 2013). This approach could also be adapted to other acaricide targets and species of ticks of medical and veterinary importance. The HRM for pyrethroid resistance SNPs could also be used in integrated control programs in other parts of the world where ticks and tick-borne diseases burden the health of humans, domestic animals, and wildlife. 5. Conclusion A quantitative PCR-based HRM assay method was developed that detects T170C, G184C, C190A, G215T, T2134A and C2136A SNPs and their combinations in the para-sodium ion channel gene of *R. microplus*. Bioassays confirmed the existence of broad spectrum pyrethroid resistance correlated with the frequency of the mutations in the tick strains evaluated. This assay provides a useful methodology to screen mutations associated with susceptibility to pyrethroids in tick populations and thus facilitates surveillance for acaricide resistance. Author contribution statement G.M.K., R.J.M., J.P.T. and A.A.P.L., oversaw the research and planned the experiments. G.M.K. and D.S. executed the bioassays, PCR, cloning and sequencing; G.M.K. and J.P.T. analyzed the data and prepared figures. G.M.K., J.P.T., D.S., R.J.M., T.P.F. D.B.T. and A.A.P.L. prepared and reviewed the manuscript. Declarations of interest None. Acknowledgements We thank Laurence Dave Kraska, Michael Moses, and Ruby Martinez for their support on the maintenance of the tick colonies, as well as Cesario Agado, James Hellums, and Homero Vazquez for the handling of animals used as tick hosts. We also thank Dr. Denise L. Bonilla, Gustavo A. Soberano, Dr. Amy Green, Dr. Camilo Potes, Dr. Albert Leslie, Dr. Amber Lasster, Dr. Walter Howe, Dr. Kayla Wells, Dr. Lilajit Rai and Dr. Nianet Carrasquillo from USDA-APHIS for the access to the field samples. G.M.K. was funded by the USDA-ARS through the Oak Ridge Institute for Science and Education (ORISE). D.S. and T.P.F.A. were supported by the USDA AFRI National Institute of Food and Agriculture program titled “Training the next generation of agricultural scientists: coping with food security and climate change challenges”, award number: 2016-67032-25013. Robert D. Mitchell III provided helpful comments on an earlier version of the manuscript. USDA is an equal opportunity provider and employer. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.ijpddr.2019.03.001. References
Dealing with Alarms in Optical Networks Using an Intelligent System DANSHI WANG¹, LIQI LOU¹, MIN ZHANG¹, ANTHONY C. BOUCOUVALAS², (Fellow IEEE), CHUNYU ZHANG¹, and XUETIAN HUANG³ ¹State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China. ²Department of Informatics and Telecommunications, University of Peloponissos, Tripoli, Greece, 22100 ³China Telecom Corporation, Beijing, 100015, China. Corresponding author: Min Zhang (e-mail: mzhang@bupt.edu.cn). This work was supported by NSFC Project No. 61705016 and the National Key R&D Program of China (2016YFB0901200). ABSTRACT Millions of alarms in optical layer may appear in optical transport networks every month, which brings great challenges to network operation, administration, and maintenance. In this paper, we deal with this problem and propose a method of alarm pre-processing and correlation analysis for this network. During the alarm pre-processing, we use the method of combined Time series segmentation and Time sliding window to extract the alarm transactions, and then we use the algorithm of combined K-means and Back propagation neural network to evaluate the alarm importance quantitatively. During the alarm correlation analysis, we modify a classic rule mining algorithm, i.e. Apriori algorithm, into a Weighted Apriori to find the high-frequency chain alarm sets among the alarm transactions. Through the actual alarm data from the record in optical layer of a provincial backbone of China Telecom, we conducted experiments and the results show that our method is able to perform effectively the alarm compressing, alarm correlating and chain alarm mining. By parameter adjustment, the alarm compression rate is able to vary from 60% to 90% and the average fidelity of chain alarm mining keeps around 84%. The results show our approach and method is promising for trivial alarm identifying, chain alarm mining and root fault locating in existing optical networks. INDEX TERMS Alarm pre-processing, K-means, back propagation neural network, alarm compression, alarm correlation analyzing, optical network I. INTRODUCTION As the scale of optical transport network (OTN) expands, the number of alarms in optical layer may reach over one million within only one week, which brings great trouble to the network operation, administration, and maintenance. For example, if alarms appear due to an overtime service delay or an extra-high bit-error-rate (BER), the network administrator has to judge the fault location promptly and correctly in order to repair the fault in time. However, the situation in actual network is very complicated. A fault is often related to a large number of alarms, including many redundant alarms. Meanwhile, there exist lots of false alarms corresponding to no fault. Therefore, it is difficult for people to find useful information promptly from such a large number of alarms. If these alarms can be compressed reasonably and automatically, the alarm analysis will be much easier, which will help the network administrator to find the root cause of the faults and restore the OTN in time. Therefore, the alarm compression has become an urgent and also tough problem in optical networking, and the premise of alarm compression is alarm correlation analysis. As an important part of the network fault management, the alarm correlation analysis is helpful for deleting redundant alarms, predicting chain alarms, and locating faults. Traditional alarm correlation analysis can find the alarms associations to a certain extent and depend mainly on the expert systems or even manual operation of the experienced staff. With the growing number of optical links and OTN systems, it is increasingly difficult for experts to keep up with the rapid changes in the network and then discover truly useful knowledge from the alarms. Most of the existing studies are based on association rule mining, correlation coefficient, or mutual information to analyze the alarm correlation [1–4]. Meanwhile, alarm association analysis based on association rule mining has been widely concerned due to its advantages of compressing alarm volume and finding high-frequency chain alarms. Typical rule mining methods are Apriori-like algorithms [5–7], which locate frequent alarm transactions by repeatedly scanning the database and present them as rules. However, there are few studies or reports on alarm analysis for optical networks and the existing methods are not very suitable for optical networks. The alarms in OTNs rise not only from the optical transport plane but also the service plane and the control plane, so that the large amount of alarms from different planes often interact with each other. As a result, if the association rules are directly mined from the original alarms, the performance of the algorithm will be degraded significantly. Moreover, the original alarms from actual optical networks always suffer from several problems (i.e., information redundant, time asynchronous, and ambiguous importance of alarm attributes, etc.), which are detrimental to alarm analysis and compression. Therefore, alarm preprocessing is required. The common methods of quantitative evaluation of the alarm importance rely on experienced network experts in determining the relative importance of alarms [8–10]. Different network experts or researchers may derive different weights for the alarms in the same network. However, the alarm number rises to tens of thousands and also the network is becoming more and more dynamic. It becomes impossible to determine the relative importance of all alarms accurately by manual operation or experts alone. To address the problem of a huge number of alarms with various attributes and of uncertain importance in the dynamic optical network, an effective and objective method of alarm importance evaluation is necessary. In an optical network, the alarm usually contains many attributes and each attribute with a wide range of values makes the alarm importance ambiguous. Therefore, it is necessary to give weights to these attributes and thus evaluate the alarm importance quantitatively. Recently, machine learning is playing an increasingly important role in optical communication research, and has been applied in diverse areas such as predicting equipment failure in optical network [11], reducing nonlinear phase noise [12,13], compensating physical impairments [14], monitoring optical performance [15,16], adaptive nonlinear decision at the receivers [17], adaptive demodulator [18], and traffic-aware bandwidth assignment [19]. In this paper, we propose the TKBW method for alarm preprocessing and alarm association rule mining. The time required for different faults to trigger a series of chain alarms is different and, therefore, we use the time sliding window (TT) to divide the original alarms into alarm sequences and thus extract the alarm transactions. Meanwhile, the alarm synchronization and redundancy removal are performed in each of alarm sequence. To address the problem of a huge number of alarms with various attributes and uncertain importance, in this paper we use KB method to give the weights to the Importance on Alarm Attributes (IAAs). After the alarm pre-processing by combined K-means and Back propagation neural network (TT-KB) method, we modified the traditional Apriori algorithm as W-Apriori algorithm to find out the association rules between alarms, and facilitate the alarm compression and fault location. The rest of the paper is organized as follows: In Section II, we discuss the principles of the alarm analysis scheme, including the TT-KB method for alarm pre-processing, the W-Apriori method for alarm correlation, and their implementation. Section III shows the experimental results and discussion. Finally, we draw conclusions in Section IV. II. PRINCIPLE OF ALARM ANALYSIS SCHEME The proposed TKBW method is mainly divided into two parts: alarm pre-processing and alarm correlation analysis. A. TT-KB BASED ALARM PRE-PROCESSING Given its present huge scale in trans-provincial backbones and metropolitans networks, there are a large number of original alarms in the existing optical network. Moreover, the original alarm data are facing the problems of information redundant, time asynchronous, and the unclear IAAs. We use the TT method to divide all the original alarms into alarm sequences. Then the alarm synchronization, redundancy removal, and alarm transaction extraction are performed for each alarm sequence via a time sliding window. But there are many alarm attributes and their IAAs are unknown, so that we use the KB method to evaluate the IAAs quantitatively. Firstly, the alarm attributes are quantized, and then the K-means algorithm is used to classify the alarms. Then, the Back propagation neural network (BP-NN) algorithm is used to infer each IAA weight. According to the network management logs in existing provincial OTN, the original alarms usually contain the following attributes: equipment name, equipment type, equipment address, network element type, alarm level, alarm name, alarm type, alarm time, subnet, and so on. Among these attributes, the equipment name can be determined by the equipment address. The network element type and its subnet are unified within a certain network segment. Therefore, as shown in Fig. 1, to start with, we extract the six attributes, the equipment address (Ea), the alarm name (An), the alarm level (Al), the alarm type (At), the equipment type (Et) and the alarm time (t) to form a new alarm, which is marked as a 6-tuple (Ea, An, Al, At, Et, t). 1) TT METHOD OF ALARM TRANSACTION EXTRACTION In the existing OTN, the number of alarms for different faults is different and the time required to form an alarm sequence is also different. Therefore, during time-segmenting of a large number of alarms, we have to ensure that a complete alarm sequence is collected. Otherwise it will affect the subsequent alarm correlation analysis. Here, we calculate the time series similarity to implement the time segmenting, which makes the alarm similarity in the same time period maximum while the alarm similarity in different time periods minimal. According to a direct calculating method of the time series similarity [20], the time interval is used as the criterion for the similarity measure among alarms, \(x, y\) as given by Eq. (1), \[ \text{dist}(x, y) = \sqrt{\sum (x - y)^2} \] (1) Thus, the intra-segment similarity function SI(t) is defined as the sum of the squares of the time intervals from each moment to the midpoint of the time period, as follows, \[ S(t) = \sum_{i=1}^{k} I(t_i) = \sum_{i=1}^{k} \sum_{t \in T_i} \text{dist}(c, t) \] (2) where \( c \) represents the midpoint of the time period \( t \). The inter-segment similarity function \( S(t) \) is defined as the sum of the time intervals between the midpoint of each time period, as follows: \[ SO(t) = \sum_{i \in S(t)} \text{dist}(c, t) \] (3) Then the sum of the squared error (SSE) is adopted as the objective function and also the index to measure the division of the time window, as given by Eq. (4): \[ SSE = \sum_{i=1}^{k} \sum_{t \in T_i} |c - t|^2 \] (4) where the optimal result is to obtain the minimal SSE. The main flow of the algorithm is attached as Algorithm I in Appendix. After the time segmenting, we use the time sliding window method [21] to perform time synchronization, redundancy removal, and alarm transaction extraction for the alarms in each time period. Time synchronization means that the alarms appearing in the same time window are regarded as concurrent alarms and are to be extracted into the same alarm transaction. In addition, if an alarm appears several times in a short interval, it is recorded only once in the same time window in order to eliminate redundant alarms. The alarm transaction refers to the collection of alarms appearing in the same time period. Regarding the time sliding window method, we give the following definitions: **Definition 1.** Time window. The given time window width is \( V \), and the time window is used to slide from the beginning of a time period until the end of the time period. **Definition 2.** The window slide step \( h \), which is the length of each movement of the time window. Figure 2 shows an example that the total alarms \{A, A, B, C, ..., C, B\} are divided into several alarm sequences (e.g., \( D_1, D_2, ..., D_k \)) according to the time series similarity calculation. Then given the window width \( V \) of 5 and the sliding step size \( h \) of 2, the time sliding window method is used to perform alarm transaction extraction for each alarm sequence. If for example alarms B(23) and B(27) occur in the same window, the alarm B is recorded only once. The time when the alarm occurs is recorded as 23s and 27s, which is expressed as B(23,27):1. Similarly if alarms A(28) and A(28) are reported multiple times at the same time, alarm A is recorded once. The alarm occurs for 28s, which is expressed as A(28):1. **FIGURE 2.** Example of alarm transactions extraction using the time sliding window. Table I gives an example of the alarm transactions extracted by the time period alarm sequence. The alarm transaction refers to the set of alarms collected in a given time window, such as \{A, B, C\}, \{B, C, E\}, \{C, E, A, B\}, \{E, A, B\}, \{B, D\}, and we treat the total alarm transactions as an alarm transaction database \( TD_1 = \{\{A,B,C\}, \{B,C,E\}, \{C,E,A,B\}, \{E,A,B\}, \{B,D\}\} \). **TABLE I** Example of the alarm transaction database \( TD_1 \) <table> <thead> <tr> <th>Transaction Name</th> <th>Items</th> </tr> </thead> <tbody> <tr> <td>T1</td> <td>A(1), B(3), C(5)</td> </tr> <tr> <td>T2</td> <td>B(3), C(5), E(7)</td> </tr> <tr> <td>T3</td> <td>C(5), E(7), A(8), B(9)</td> </tr> <tr> <td>T4</td> <td>E(7), A(8), B(9)</td> </tr> <tr> <td>T5</td> <td>B(9), D(10)</td> </tr> </tbody> </table> 2) QUANTITATIVE EVALUATION OF ALARM IMPORTANCE To evaluate the alarm importance quantitatively, it is necessary to assign IAA weights (Fig. 4). We apply the KB method where the alarm attributes are taken as the input and the alarms with similar attributes are classified into the same class by the K-means algorithm. Then both the alarm attributes and the classifications are taken as the input of the BP-NN to train the connection weights between the neurons, so that the connection weights map the information of the alarm attributes, and thus obtain IAA weights. According to the advice of experienced network administrators and by observation of the alarm sets and the fault sets in the actual network logs, we select three alarm attributes that are most closely related to the faults as the initial sample input, i.e., \( A = \{Al, At, Et\} \) in Fig. 1. Each attribute in the collection has several values that indicate the relative importance. Here we use the K-means algorithm to automatically classify similar alarm samples, and get the comprehensive alarm classifications after fully considering these three alarm attributes. We rewrite Eq. (1) as Eq. (5), where \( x_i \) and \( x_j \) represent the attribute values, and \( D \) represents the number of attributes. \[ \text{dist}(x_i, x_j) = \sqrt{\sum_{d=1}^{D}(x_{i,d} - x_{j,d})^2} \] (5) All alarms are divided into K classes, denoted as \( C_1 \), \( C_2 \), ..., \( C_k \). Then, we take \( A = \{Al, At, Et\} \) as the input and the K alarm classes as the labels to train a stable BP-NN model owing to the strong self-learning and fitting ability of the neural network. Thus, via the method in [22], the connection weights of neurons are mapped to the IAA weights, as given by Eq. (6): \[ \text{Feature}_{x} = \sum_{x_{\text{Hidden}}} x_{\text{Hidden}} \] (6) where \( X \) is the weight matrix between the input layer neurons and the hidden layer neurons, and \( Y \) is the weight matrix between the output layer neurons and the hidden layer neurons. Finally, we give the score of the alarm importance as Eq. (7), where \( N \) is the number of inputs. \[ W = \frac{1}{N} (\text{Feature}_{x} \times Al + \text{Feature}_{x} \times At + \text{Feature}_{x} \times Et) \] (7) B. W-APRIORI BASED ALARM CORRELATION ANALYSIS The score of the alarm importance is helpful for setting a threshold and thus discard those trivial alarms and false alarms. For the remaining alarms, correlation analysis is still needed to obtain chain-alarm. The existing correlation analysis method is not designed for optical networks and they do not consider the difference in alarm importance. For example, the typical Apriori algorithm treats different alarms as equal, and there is no difference in the alarm attributes. However, in an actual optical network, an alarm usually consists of many attributes, and different attribute combinations indicate different alarm severities. When mining the alarm correlation, we improve the Apriori algorithm as W-Apriori, in which the score of alarm importance is used as the weight. Given a database $D$ with a set of alarm transactions $D = \{T_1, T_2, \ldots, T_m\}$, where $T_j$ ($j=1,2,\ldots,m$) is the set of alarms collected within time window. $I=\{i_1, i_2, \ldots, i_n\}$ is the set of all alarms in the database, and each alarm transaction set $T_j$ is a subset of $I$ (i.e. $T_j \subseteq I$). The set of alarm scores in the corresponding alarm set I can be expressed as $W = \{W_1, W_2, \ldots, W_n\}$ ($0 \leq W_j \leq 1, j = 1, 2, \ldots, n$), and $W_j$ is the score of the alarm $i_j$. In traditional Apriori, the association rule is the expression of the form $X \Rightarrow Y$, where $X$ and $Y$ are disjoint item sets (i.e. $X \cap Y = \emptyset$). The strength of the association rule is measured by its support and confidence. The support determination rules can be used for the frequency of the given data set, and the confidence determines how frequently $Y$ appears in transactions that contain $X$. The W-Apriori algorithm redefines the above two. **Definition 3.** Weighted Support. The traditional support of pattern $X(\subseteq I)$ is denoted as $\text{Support}(X)=\text{Count}(X)/|D|$, where $\text{Count}(X)=\{T|X \subseteq T, T \in D\}$ is the number of transactions for which item set $X$ appears in $D$, and $|D|$ is the total number of transactions in $D$. Then the weighted support ($w\text{Support}$) of $X$ is defined as Eq. (8), where $n$ is the number of items in $X$. Meanwhile, $\text{minwSup}$ is used to represent the minimum weighted support threshold, which is used to evaluate the minimum limit of the transaction frequency. $$w\text{Support}(X) = \text{Support}(X) \times \left(\sum_{j=1}^{n} W_j\right)$$ \hspace{1cm} (8) **Definition 4.** Weighted Confidence. The traditional confidence of a rule $X \Rightarrow Y$ is $\text{Confidence}(X \Rightarrow Y) = \text{Support}(X \cup Y)/\text{Support}(X)$. Then the weighted confidence ($w\text{Conf}$) of a rule $X \Rightarrow Y$ is defined as Eq. (9), where $n$ is the number of items containing the union of $X$ and $Y$, and $m$ is the number of items in $X$. Meanwhile, $\text{minwConf}$ is used to represent the minimum weighted confidence threshold, which is used to evaluate the minimum limit of the transaction association. $$w\text{Conf}(X \Rightarrow Y) = \frac{\text{Support}(X \cup Y) \times \left(\sum_{j=1}^{n} W_j\right)}{\text{Support}(X) \times \left(\sum_{j=1}^{m} W_j\right)}$$ \hspace{1cm} (9) **Definition 5.** Weighted Frequent itemsets. Given a database $D$ and a weighted support threshold $\text{minwSup}$, if a pattern $X$ satisfies: $w\text{Support}(X) \geq \text{minwSup}$. Then $X$ is the weighted frequent itemsets. Therefore, the purpose of the W-Apriori algorithm is to find all the association rules where the $w\text{Support}$ and the $w\text{Conf}$ satisfy the conditions $w\text{Support} \geq \text{minwSup}$ and $w\text{Conf} \geq \text{minwConf}$ in the given alarm database $D$ respectively. The description of the W-Apriori algorithm is given as Algorithm II (seen in Appendix). ![FIGURE 3. Execution process of W-Apriori algorithm.](image) Figure 3 is an example to illustrate the implementation of the W-Apriori algorithm. We use the alarm transaction database $D_1$, given in Table I, which contains 5 alarm transaction sets: $\{A, B, C\}, \{B, C, E\}, \{C, E, A, B\}, \{E, A, B\}, \{B, D\}$, where $\text{minwSup} = 50\%$ is used as the minimum support threshold. The W-Apriori algorithm uses an iterative strategy of layer-by-layer search: in the $k$-th cycle, frequent $k$-itemsets are generated through a combination of the transaction database and candidate $k$-itemsets, and then a new candidate $(k+1)$-itemsets are generated based on the $k$-itemsets. And so on, the algorithm stops until the maximum itemset of a cycle is empty. Finally, we filter out high-frequency chain-alarm $\{A, B\}, \{B, C\}$, and $\{B, E\}$. ### C. IMPLEMENTATION OF TKBW ALGORITHM The application scenario of the alarm analysis scheme is shown in Fig. 4. In the OTN network, the alarm data in optical layer collected through the network management system or the controller in software defined optical network (SDON), and then the TKBW method is used for alarm analysis. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/. Figure 5 illustrate the overall principle of the TKBW method. TKBW consists of two modules, i.e., an alarm pre-processing module and an alarm correlation analysis module. The alarm pre-processing module extracts the alarm transaction and evaluates the alarm weight and converts the alarm data into alarm transactions suitable for correlation analysis. The alarm correlation analysis module is used to mine the association rules from the alarm transactions, and thus finds out the chain alarms. The procedure of the TKBW method is shown as follows. Step 1. Collecting the alarms and select the useful alarm attributes; Step 2. Extracting the alarm transactions by using TT method; Step 3. Scoring the alarm importance by using KB method; Step 4. Analyzing the alarm correlation with W-Apriori algorithm and find out the chain alarms. III. EXPERIMENTS AND DISCUSSIONS Experiments were conducted with the alarm data from the network log of optical layer equipment in a provincial backbone of China Telecom that contains 441 OTN nodes. We collected 5,100,000 original alarms within 30 days. The proposed TKBW method was developed via Python and implemented on a computer with Windows 7 operating system, Intel(R) Core (TM) processor i5-4345 with 2G main memory. FIGURE 4. Application scenario of the alarm analysis scheme. FIGURE 5. Schematic diagram of TKBW method. A. ALARM TRANSACTION EXTRACTION First, the original alarm data of the first 20 days were used as the test data, and Step 1 and Step 2 in TKBW procedure were performed to extract the alarm transaction. In the actual OTN, the operator generally uses the alarm data extracted every 15 minutes, which is not extracted in real time. Therefore, we divided all the alarms per day by intervals of 15 minutes and thus got averagely 90 alarm transaction databases per day, namely D1, D2, ... and D90. Then, a time sliding window processing was performed for each alarm transaction database to extract the alarm transactions. Here we set the window width V as 5 minutes and the sliding step has 2 minutes. We compared the time consumption of alarm transaction extraction by the TT method and the uniform time (UT) window method. It can be seen from Fig. 6 that the more complex TT method takes slightly longer time than the UT method does. And as the alarm transaction number increases, the difference fades away. We still prefer to use the TT method because it fully considers the unevenness of the distribution of alarm data, and also can remove the isolated points and abnormal points as invalid alarms. ![Comparison of the time consumptions in extracting alarm transactions by TT method and UT method.](image1) After the K-means classification, all the alarms were automatically classified into four classes, recorded as C1, C2, C3 and C4, respectively. Then, this classification was used as the input label of BP-NN, where the connection weights of all BP-NN neurons were obtained through BP-NN feedback learning. Here, we considered the effect and complexity of the algorithms, and set numbers of the input, output and hidden layers of BP-NN as 3, 4 and 10 respectively, and set the learning rate as 0.01. Fig. 8 shows the connection weight between the input neurons and the first hidden layer neurons during BP-NN training, which changes with the number of training iterations. It can be seen that after 10 epochs of iteration, the connection weight tends to be convergent, which shows that it is feasible to score the alarms and their attributes. ![Connection weights vary with the iteration epoch of BP-NN.](image2) B. QUANTITATIVE ANALYSIS OF ALARM IMPORTANCE In step 3, according to the advice of experienced network administrators, we selected three alarm attributes that are the most closely related to the faults, namely, alarm level Al, alarm type At, and alarm equipment type Et. These three attributes were initialized. For example, for alarm level Al, we initialized emergency as 1, importance as 2, secondary as 3 and prompt as 4. Then, the alarm transactions with initialized attributes were taken as the input of K-means algorithm, where the alarms with similar attributes were divided into the same class. As shown in Fig. 7, after about 15 iterations, the mean squared error of classification converged to 1.5, indicating that the K-means algorithm is trained. ![Mean square error varies with the iteration epoch of K-means.](image3) In the above, we marked the output classifications (C1 to C4) by K-means as four different values, but these values are in fact only tags of the classes and they are not necessarily the only representations. Therefore, there are 24 kinds of combinations when assigning 1~4 to C1~C4 respectively. We repeated the above experiment with different combinations of the initial values of C1~C4 and then calculated the IAA weights given by Eq. (6). The results are shown in Fig. 9. It can be seen that, although with different initial values, via the classification of K-means and BP-NN, the IAA weights are able to be stabilized at around 0.55, 0.25 and 0.20 respectively. It indicates that the combined algorithm of K-means and BP-NN works independent of the initially quantized values. Therefore, the idea of giving quantitative evaluation to the alarms and the abstract alarm attributes works. Then, the scores of alarms can be calculated according to Eq. (7), and the wSupport and wConfidence of alarms can be calculated according to Eq. (8) and Eq. (9). Thereafter, as illustrated by the C1 step in Fig.3, we obtained the wSupport for each alarm and then deleted those alarms whose wSupports are less than the minwSup. Here, the minwSup acts as a threshold for the preliminary alarm compression and this threshold should be assigned according to the requirements of the actual network management. Next, we tested the effects of alarm number on the performance of both algorithms. Fig. 11 shows the time consumptions for mining 10,000 to 100,000 alarm transactions by both algorithms, with a fixed minwSup of 0.2. As the alarm number increases, the time consumption of both algorithms become longer, but the W-Apriori outperforms the Apriori gradually. With larger alarm number, the advantages of W-Apriori becomes more obvious. Both Fig. 10 and Fig. 11 show that the modified W-Apriori outperforms W-Apriori in terms of time consumption, since the W-Apriori considers the alarm importance and thus removes a large number of redundant alarms (e.g., false alarms). Figure 12 presents the comparison of the compressed alarm collection number by both algorithms, with various minwSups and with a fixed alarm transaction number of 10,000. To some extent, the same minwSup means that the same compression fidelity can be obtained. Fig. 12 indicated with the same compression fidelity, W-Apriori works more effectively and leads to fewer alarm collections. C. ALARM CORRELATION ANALYSIS AND ALARM COMPRESSION After the preliminary alarm compression, we analyzed the correlation among the remaining alarms and explored ways to compress the alarms in terms of alarm compression rate and fidelity. First, the time consumptions of the traditional Apriori and the modified W-Apriori were compared, as shown in Fig. 10, where the number of alarm transactions sets is 100,000 and minwSup changes from 0.1 to 0.6. As the minwSup increases, the time consumptions of both algorithms decrease gradually. The main reason is that when the threshold minwSup is small, more alarm transaction sets need to be processed. In addition, the W-Apriori takes less time than the Apriori does. over the number of total original alarm collections. It can be seen that as \( \minwSup \) increases from 0.1 to 0.2 and then to 0.3, the alarm compression rates rises from 67% to 82% and then to 89%, respectively. That is, larger \( \minwSup \) yields higher compression rate. In other words, with larger \( \minwSup \), more alarms will be removed as false alarms. Moreover, given a fixed \( \minwSup \), the compression rate remains almost stable, independent of both the training samples in the first 20 days and the application samples in the last 10 days, which indicates that the W-Apriori works stable and has little deviation between the training samples and the application samples. The results above also indicate that, by adjusting the \( \minwSup \), we are able to obtain different compression rates for different purposes. Higher alarm compression rate is not necessarily desired, for that we must consider the compression fidelity, which is defined as follows. After the alarm compression, the collections of high-frequency chain alarms were obtained. We assume that the high-frequency chain alarms are the substantial key alarms that can represent the actual faults, and the location of the fault nodes are known. Then, we define compression fidelity as the proportion of the compressed high-frequency chain alarms occurrence location containing the actual fault node location in each time period. We measured the quality of the alarm compression in terms of compression fidelity. Fig. 15 shows the variation of compression fidelity with different \( \minwConf \)s when \( \minwSup \) is 0.1. Here, we set \( \minwConf \) to a smaller value, mainly in order to retain a large number of original alarm collections and facilitate the statistical experiment results. It can be seen that as the \( \minwSup \) is 0.1 or 0.2, the fidelity keeps relatively high, namely 84% and 80% respectively, indicating that after alarm compression with such a \( \minwSup \), the high-frequency chain alarms can reflect the actual fault situation to a large extent. However, as the \( \minwSup \) is 0.3, too much alarms are removed during compression and thus the fidelity remains even lower than... 60%, which means in this case the alarm compression is not very believable. Moreover, from Figs. 14 and 15, it can be seen that when \textit{minwSup} is 0.2, the obtained alarm compression rate is 15% larger than when \textit{minwSup} is 0.1, which indicates that when the \textit{minwSup} is 0.2, the original alarms can be compressed to a larger extent while relatively high compression fidelity is kept. Therefore, considering both the alarm compression rate and fidelity, it may be appropriate to select the \textit{minwSup} threshold as 0.2. However, in actual optical network, the \textit{minwSup} threshold should be set to a particular optimal range of values according to the network scale. If the threshold is set too small, many redundant alarms (e.g., false alarms) will be retained, which is not conducive to the subsequent alarm correlation analysis and alarm compression; if the threshold is set too large, some important alarms (e.g., substantial alarms) will be removed. Therefore, in practical operation, it is necessary to set a threshold according to actual OAM requirements and operational effects. **FIGURE 15. Compression fidelity with different minwSups.** According to the experimental results, the TKBW method can effectively perform alarm compression, alarm correlation analysis and chain alarm mining to implement the compression of alarms and obtain high-frequency chain alarms. This means that we can use high frequency chain alarms to find the root fault nodes location. Moreover, the method is not complicated in implementation. Therefore, the proposed method is easy to set up in the controller. However, since the experimental data have come from the actual alarm monitoring record in optical layer of a provincial backbone of China Telecom, the number of alarm attributes of the fiber layer equipment is small and the attributes are relatively thick. Our method cannot fully guarantee that all OTNs are applicable. If there are more data from different OTNs, a more complete analysis method can be proposed and the universality of the method can be verified. In addition, we extracted six important and valid attributes in the experiment. If we change the number of alarm attributes (e.g., reduce the number of alarm attributes) and re-experiment, weather we get the same results will require further testing and analysis. Whatever the outcome, the proposed scheme offers a good promising model, which is interesting and will needs further future research. **IV. CONCLUSION** To deal with the problem of coping with the huge number of Alarms in OTNs, we have proposed the TKBW method, which offers alarm compression and high-frequency chain alarms mining. By taking actual data of network logs from China Telecom, we have conducted experiments, the results of which show that the TKBW method is able to give a score to indicate the importance of each alarm and the score is independent of the initial quantization values. In addition, the TKBW method is able to mine the chain alarms and compress the alarms to a rate on demand by adjusting parameters, such as \textit{minwSup}. The results are promising and helpful for false alarm identifying and root failure locating. **APPENDIX** **ALGORITHM I** Time Division Method based on Similarity of Time Series **Input:** \( k \): the number of time segments \( n \): database containing \( n \) alarm events **Output:** \( k \): \( k \) time intervals with minimum sum of squared errors 1: Select initial cluster center points for \( k \) time segments; 2: for \( (i = 1; j < n; i++) \) { 3: Assign each \( t_i \) to the time interval which has the closest mean; 4: for \( (i = 1; i < k; i++) \) { 5: find the cluster center point \( c_i \) for each time segment; 6: compute \( SSE = \sum_{i=1}^{k} \sum_{t \in c_i} |t - c_i|^2 \); 7: Repeat until \( SSE \) converged. **ALGORITHM II** W-Apriori Algorithm **Input:** \( D \): transaction database \( \text{minsup} \): minimum support threshold **Output:** \( L_k \): frequent \( k \)-itemsets of \( D \) 1: \( L_1 = \text{FindFrequent}_1\text{-itemsets}(D); \) 2: ///generate the frequent 1-itemsets 3: for \( (k = 2; L_k \neq \emptyset; k++) \) { 4: \( C_k = \text{Genetate Candidates}(L_{k-1}, \text{minsup}); \) 5: ///generate the new candidate itemsets 6: for each transaction \( t \in D \) { 7: \( C = \text{subset}(C_k,t); \) 8: ///find out all candidate \( k \)-itemsets contained in transaction \( t \) 9: end \( for \) 10: \( L_k = \{ c \in C_k | \text{support} \geq \text{minsup} \}; \) 11: end \( for \) 12: return \( L = \cup L_k; \) **ACKNOWLEDGMENT** We would like to acknowledge the China Telecom Corporation for providing the network data, and the... support from the Fundamental Research Funds for the Central Universities (2019RC12). REFERENCES
Conditional β1-integrin gene deletion in neural crest cells causes severe developmental alterations of the peripheral nervous system Thomas Pietri1,*, Olivier Eder1, Marie Anne Breau1, Piotr Topilko2, Martine Blanche1, Cord Brakebusch3, Reinhard Fässler3, Jean-Paul Thiery1 and Sylvie Dufour1,† 1UMR144, CNRS – Institut Curie, 26, rue d’Ulm, 75248 Paris Cedex 05, France 2U 368, INSERM – Ecole Normale Supérieure, 46, rue d’Ulm 75230 Paris Cedex 05, France 3Max Planck Institute of Biochemistry, Department of Molecular Medicine, Martinsried, 82152, Germany *Present address: Department of Neuroscience, The Johns Hopkins School of Medicine, 725 North Wolfe Street, 1001 PCTB, Baltimore, MD 21205, USA †Author for correspondence (e-mail: sylvie.dufour@curie.fr) Accepted 30 April 2004 Development 131, 3871-3883 Published by The Company of Biologists 2004 doi:10.1242/dev.01264 Summary Integrins are transmembrane receptors that are known to interact with the extracellular matrix and to be required for migration, proliferation, differentiation and apoptosis. We have generated mice with a neural crest cell-specific deletion of the β1-integrin gene to analyse the role of β1-integrins in neural crest cell migration and differentiation. This targeted mutation caused death within a month of birth. The loss of β1-integrins from the embryo delayed the migration of Schwann cells along axons and induced multiple defects in spinal nerve arborisation and morphology. There was an almost complete absence of Schwann cells and sensory axon segregation and defective maturation in neuromuscular synaptogenesis. Thus, β1-integrins are important for the control of embryonic and postnatal peripheral nervous system development. Key words: Integrin, Peripheral nervous system, Neural crest cells, Conditional knockout Introduction The ontogeny of neural crest cells (NCC) is a major morphogenetic process involving various biological steps, such as epithelium-mesenchyme transition, cell migration and cell aggregation. NCC differentiate to generate a diversity of cell types, including craniofacial structures, the peripheral nervous system (PNS) and melanocytes (Le Douarin, 1982; Le Douarin and Kalcheim, 1999). NCC interact with the extracellular matrix (ECM) during their differentiation. Integrins are αβ heterodimers that bind ECM components and cell-surface receptors, and control cell adhesion, migration, differentiation and survival (Hynes, 2002). Previous studies have shown that integrins play a major role in the control of NCC adhesion and migration. In vitro, these cells express a large repertoire of integrins, including α1β1, α3β1, α4β1, α5β1, α6β1, α8β1, αVβ1, αVβ3 and αVβ8 (Kil et al., 1996; Desban and Duband, 1997; Testaz et al., 1999). In vivo, functional analyses with integrin antibodies, antisense oligonucleotides and peptide competitors have shown that mouse and avian NCC use multiple β1-integrins (Boucaut et al., 1984; Bronner-Fraser, 1986; Poole and Thierry, 1986; Kil et al., 1998). Constitutive knockout of the β1-integrin gene leads to the loss of twelve members of the integrin family and leads to death of the embryo during the peri-implantation period due to inner cell mass failure (Fässler and Meyer, 1995; Stephens et al., 1995). This constitutive β1-knockout model demonstrates the essential role of β1-integrins during early embryogenesis, but is of no use for investigating integrin functions during later stages of development or in differentiated cells, such as NCC derivatives. By contrast, neither the invalidation of individual α-integrin subunits (for reviews, see Bouvard et al., 2001; Hynes, 2002) nor the production of knockout chimaeric mice (Fässler and Meyer, 1995) has made it possible to delineate precisely the roles of specific integrins during NCC development, with the exception of α5β1-integrins, which have been implicated in cranial NCC survival (Goh et al., 1997), and α5β1- and α4β1-integrins, which have been implicated in the proliferation or survival of glial cell precursors (Haack and Hynes, 2001). The Cre-LoxP conditional gene disruption system has been used to investigate the effect of integrins on NCC ontogeny in more detail. P0-Cre mice crossed with mice carrying a floxed β1-integrin allele generated animals with the conditional mutation targeted specifically to Schwann cells (SC), which are derived from NCC (Feltri et al., 2002). This conditional knockout revealed the role played by β1-integrin receptors in postnatal PNS development. The loss of β1-integrins impedes interactions between SC and axons, causing dysmyelinating neuropathy (Feltri et al., 2002). We recently developed the Ht-PA-Cre transgenic mouse line, in which Cre recombinase activity is targeted specifically to NCC at the start of migration (Pietri et al., 2003). We report here the effects of specific inactivation of the β1-integrin gene in migratory neural crest cells. The crossing of Ht-PA-Cre mice with β1 floxed mice generated animals in which the NCC produce no β1-integrin but do produce β1-galactosidase under the control of the endogenous β1-integrin promoter (Potocnik et al., 2000). The mutation targets the glial and sensory neuronal compartments of the PNS as well as the other NCC derivatives. We show here that β1-integrin receptors control PNS development at both early and late stages. The absence of β1-integrins delayed the migration of SC along nerves and resulted in abnormal axo-glial segregation, especially for sensory axons. Substantial changes were observed in the pattern of subcutaneous and muscular innervation. In addition, the arborisation and fasciculation of the innervating fibres and their targeting to the distal tissues were abnormal, and neuromuscular synaptogenesis appeared to be blocked in a state of immaturity. Finally, the mutation caused the death of the animals by the age of three weeks, owing to multiple defects affecting various NCC derivatives. Materials and methods Mouse maintenance and genotyping Homozygous Ht-PA-Cre mice were crossed with mice heterozygous for the β1-integrin gene (β1+/β1+) to generate Ht-PA-Cre;β1+/β1− breeder males. These males were then crossed with β1+/β1− females to produce Ht-PA-Cre;β1−/β1− mice, referred to as mutants, and Ht-PA-Cre;β1+/β1− mice, referred to as controls in the text. Wild-type and β1+/β1− heterozygous embryos were used as controls for integrin levels in homozygous and heterozygous NCC-derived tissues. Mice were reared and experiments carried out according to the guidelines of the CNRS ethics committee. Ht-PA-Cre and β1-integrin mouse genotyping was carried out as described by Pietri et al. and Potocnik et al. (Pietri et al., 2003; Potocnik et al., 2000), respectively. Reagents and antibodies The partially purified mouse monoclonal antibody (clone 2H3) against the 160 kDa neurofilament (NF-160) protein was obtained from Developmental Studies Hybridoma Bank. Mouse monoclonal antibodies against the nuclear factor Hu-D (clone 16A11) and against the major myelin protein P0 were gifts from J. A. Weston (Marusich Developmental Studies Hybridoma Bank. Mouse monoclonal genotyping was carried out as described by Pietri et al. and Potocnik et al. (Pietri et al., 1994) and J. J. Archelos (Archelos et al., 1993), respectively. The rabbit polyclonal antibody against laminins was obtained from Sigma. The rabbit polyclonal antibodies against tenascin and S100, and the mouse monoclonal antibody against fibronectin were obtained from Chemicon. In some cases, we used a rabbit polyclonal antibody against S100 produced by Dako. The mouse monoclonal antibody (clone SY38) against synaptophysin was obtained from Progen. The rabbit polyclonal antibody against cleaved caspase 3 (Asp175) was obtained from Cell Signaling. The rabbit polyclonal antibody against Kif67 was obtained from NovoCastra and the goat polyclonal antibody against parvalbumin was purchased from Swant. The α-bungarotoxin (α-BTX) biotin-conjugated compound extracted from Bungarus multicinctus venom was purchased from Molecular Probes. Secondary antibodies conjugated with Alexa 488, cyanin 3 or horseradish peroxidase (HRP) were purchased from Molecular Probes, Jackson Laboratories and Amersham Pharmacia Biotech, respectively. Histology, immunohistochemistry and microscopy For the detection of β-galactosidase activity, embryos or organs were dissected in cold phosphate-buffered saline (PBS), pH 7.6, supplemented with 5% foetal calf serum (FCS), were fixed in toto in freshly prepared ice-cold 1% formaldehyde/0.2% glutaraldehyde/0.02% Nonidet-P40 for 2-4 hours and processed as described elsewhere (Dufour et al. , 1994). Whole-mount immunostaining was performed on embryos fixed in methanol Carnoy fixative or 4% PFA. Samples were incubated overnight in blocking solution composed of 0.3% Triton X100, 0.5× Blocking Reagent (Roche Applied Science), and 10% foetal calf serum in PBS and then for 2 days each with primary and secondary Alexa 488- or HRP-conjugated antibodies. Samples were thoroughly washed between incubations. HRP activity was detected with the VECTOR® peroxidase substrate kit, according to the manufacturer’s instructions (Vector Laboratories), followed by benzyl-benzoate solution (BABB) treatment for the detection of deep stained structures. For histological and immunohistochemical analysis of sections, fixed samples were dehydrated and embedded in paraplast Plus. They were then cut into serial sections of 7-10 μm and the wax removed. Some whole-mount stained embryos were serially sectioned at a thickness of 200 μm on a vibratome. Sections were incubated for 2 hours in blocking solution consisting of 10% FCS/0.1% Triton X100/0.5× Blocking Reagent (Roche Applied Science) in PBS. The sections were then incubated overnight at 4°C with primary antibodies in blocking solution, rinsed several times in PBS and incubated with secondary antibodies for 2 hours at room temperature in the dark. Cell proliferation was assessed by counting more than 2500 DRG cells in every second section of three different embryos of each genotype and analysing staining for the Kif67 marker. Results are expressed as the percentage of cells that were Kif67-positive. Statistical significance was determined with the ANOVA unpaired t-test. Acetylcholine receptors (AChR) were detected with α-BTX. The abdominal, diaphragm, soleus and gastrocnemius muscles of animals at times P1 and P21 were dissected in cold PBS, pH 7.6, and were then incubated for 2-3 hours at 37°C in α-BTX in minimum essential culture medium. The samples were rinsed three times, for 1 hour each, in cold PBS, fixed in 4% PFA for thirty minutes and processed as for whole-mount samples used for immunostaining. Whole-mount stained samples and histological sections were photographed under a Leica M288 stereomicroscope (Leica Microsystems SA) equipped with a JVC 3CCD colour camera. Confocal images were obtained for muscle preparations on a Leica TCS-4D confocal microscope based on a DM microscope interfaced with an Ar/Kr laser. Stacks of images were mounted with Metamorph 5.0, and normalised to the same width on the z-axis. Semi-thin sections and electron microscopy Postnatal sciatic nerves were isolated from control and mutant animals perfused with 0.5% glutaraldehyde in phosphate buffer (PB, pH 7.4), fixed in 0.5% glutaraldehyde for 1 hour at 4°C and washed in PB. β-Galactosidase activity was detected histochemically by incubating samples in PB supplemented with 5 mM potassium ferricyanide, 5 mM potassium ferrocyanide, 2 mM magnesium chloride and 1 mg/ml Bluo-gal (5-bromo-3-indolyl-β-D-galactoside, Sigma) as a substrate for 12 hours at 30°C. The following day, samples were post-fixed by incubation in 1.6% glutaraldehyde in PB for 1 hour at 4°C followed by 1 hour in 1% OsO4 (Sigma) in PB. They were then washed in PB, dehydrated in ethanol (30%, 50%, 70%), stained by incubation with 1% uranyl acetate in 70% ethanol for 1 hour, dehydrated in ethanol (80%, 90%, 100%), infiltrated and embedded in Durcupan (Fluka). Ultrathin sections were cut and stained with uranyl acetate and lead citrate. The sections were observed with a Tecnai 12 (FEI, Phillips) electron microscope. Results Generation of conditional knockout mice lacking β1-integrins in NCC The aim of this study was to investigate the role of β1-integrins in the relationships between the various component-derived NCC of the PNS (Fig. 1A, lower panel). β1-integrin gene knockout has been reported to be lethal at E5.5 because of inner cell mass failure, whereas heterozygous animals are normal and fertile (Stephens et al., 1995). We restricted inactivation of the gene encoding the β1-integrin subunit to the NCC by crossing mice homozygous for the floxed β1-integrin allele (β1flo/β1flo) with mice homozygous for Ht-PA-Cre transgene and heterozygous for the β1-integrin gene (Ht-PA-Cre/β1heterozygous). Cre recombinase-mediated deletion of the floxed β1 gene resulted in recombination to give an intact lacZ reporter gene under the control of the endogenous β1-integrin gene promoter (β1 pr). This made it possible to follow the spatiotemporal pattern of floxed allele recombination in the affected cells visually (Potocnik et al., 2000). Crosses typically generated Mendelian segregation of the two types of embryonic genotype: Ht-PA-Cre;β1flo/β1heterozygous animals, which were heterozygous for the β1-integrin gene in NCC cells and their derivatives, and wild-type for this gene in other tissues. The Ht-PA-Cre;β1heterozygous embryos were used as controls because β1-integrin gene heterozygosity has no effect on mice phenotype (Fassler and Meyer, 1995; Stephens et al., 1995). As with the Ht-PA-Cre;β1heterozygous mutants, β-galactosidase activity was detected in the developing enteric nervous system (Fig. 1B, white arrowheads). Disappearance of $\beta$1-integrins in NCC derivatives of mutant embryos The $\beta$1-integrin subunit is ubiquitously produced during embryogenesis. In the mutant, we observed a progressive loss of the $\beta$1-integrins in targeted structures. Two days after deletion of the gene in migrating NCC, faint expression of $\beta$1-integrins was still detected in NC-derived cells such as the mesenchyme of branchial arches at E10 (Fig. 1C, arrowhead) and DRG cells at E12.5 (Fig. 1E, arrowhead), compared with the controls (Fig. 1D,F, arrowhead, respectively). A complete loss of $\beta$1-integrins from the surface of the NC-derived cells was achieved at E13 in the DRG of the mutant embryos (Fig. 1G, arrowhead) whereas in the heterozygous (Ht-PA-Cre; $\beta$1 – / $\beta$1 + ) and control embryos, NC-derived cells produced detectable amounts of $\beta$1-integrins (Fig. 1H,I, respectively, arrowhead). Transverse sections of E13 mutant and control embryos were labelled for Hu-D (a specific marker of early differentiating neurons), DAPI and $\beta$1-integrins. In the DRG of the mutant embryos, the neurons (stained for the Hu-D marker; Fig. 2A,D, arrows) and the glial cells (not stained for this marker; Fig. 2D, arrowheads), did not express $\beta$1-integrins compared to the control embryos (Fig. 2E,H, arrows and arrowheads, respectively). Cells not producing the Cre recombinase, such as vessels in the DRG and surrounding tissues (Fig. 1G, arrows), displayed $\beta$1-integrin levels similar to those observed in heterozygous embryos (Fig. 1H, arrows). PNS development is altered in mutant embryos At E10.5, the condensing DRG displayed no phenotypic alteration in mutants. These structures, which displayed $\beta$-galactosidase activity, were similar in size and structure to those of control embryos (Fig. 3A,B, respectively). Hu-D was distributed similarly in the mutant and control mice (Fig. 3C,D, respectively). By contrast, 70% of the E10.5 mutant embryos ($n$=17, from four different litters) displayed changes in the patterning of the cranial nerves (Fig. 3F) with respect to control embryos ($n$=15; Fig. 3E). Fifty-nine percent of the mutants exhibited a decrease in the number of vagus nerve (X) roots (Fig. 3F, white arrowhead), 24% had a fusion of nerves IX and X (Fig. 3F, black arrowhead) and 12% had an absence of nerve IX, whereas the placode-derived ganglion IX was present (not shown). The phenotypically altered mutants often displayed two of these defects (see Fig. 3F). From E11.5, in contrast to what was observed on E10.5, nerves IX and X were present and not fused in mutants (Fig. 3H; $n$=18). Most of the mutant embryos displayed a cranial nerve pattern very similar to that of the controls (Fig. 3G; $n$=12). The more severely affected E11.5 mutant embryo exhibited some alterations of the fasciculation of vagus nerve roots (Fig. 3H, white arrowhead) compared with the control embryos (Fig. 3G). At E12.5-E13.5, the trunk nervous system displayed abnormalities, with the partial disappearance of $\beta$-galactosidase staining at the sites of muscular and subcutaneous innervation of the thoracic-abdominal body wall and limbs in the mutant embryos (Fig. 4B,D). Four different litters were analyzed and all the mutants exhibited this phenotype. On 200 $\mu$m transverse sections, $\beta$-galactosidase-positive structures were not observed in the distal part of the developing nervous system in mutant embryos (white arrows, Fig. 4D), in contrast to what was observed in controls (Fig. 4A,C). $\beta$-Galactosidase is difficult to detect in axons, on whole-mount embryonic preparations, because it is mainly localized in the cytoplasm of the cell body. Therefore, to determine whether the defect in the distal part of the innervation network in the mutants was due to the absence of axons or glial cells, we carried out NF-160 immunolocalisation on 200 $\mu$m transverse sections of E13.5 embryos stained for $\beta$-galactosidase activity. Axons were present and reached their 3875 β1-integrins in PNS development Fig. 3. Morphology of the PNS in control and mutant embryos on E10.5 and E11.5. (A,B) Detection of β-galactosidase activity after targeted deletion of the floxed β1-integrin locus in whole-mount control (A) and mutant (B) embryos, in the DRG and spinal nerves in the trunk on E10.5. (C,D) Hu-D immunolocalisation in transverse sections of control (C) and mutant (D) thoracic DRG of E10.5 embryos. (E-H) Whole-mount NF-160 immunostaining labels cranial sensory nerves in control (E,G) and mutant (F,H) embryos on E10.5 (E,F) and E11.5 (G,H), respectively. E11.5 embryos were treated with BABB. The position of nerves is indicated in E. The black arrowhead in F illustrates the fusion of nerves IX and X in the mutant on E10.5. The white arrowhead indicates a decrease in the number of nerve X roots at the same stage. On E11.5, structures are similar in the control (G) and mutant (H) embryos, except for certain changes to the fasciculation of nerve X roots in the mutant, which exhibits the strongest alteration (white arrowhead in H). Fig. 4. Morphology of the spinal nerves in control and mutant embryos, on E12.5 and E13.5. (A-H) β-Galactosidase activity was detected in whole-mount preparations. Lateral view of control embryo (A) showing intense labelling of craniofacial structures and PNS. The mutant (B) displays an absence of labelling in the trunk PNS. The 200 μm transverse sections of whole-mount E13.5 control (C) and mutant (D) embryos reveal the loss of reporter gene expression in the distal part of the mutant innervation network (white arrows in D). (E-H) Detail of cutaneous lateral ramus and lateral muscular innervation. The immunolocalisation of NF-160 on similar 200 μm transverse sections from control (E,F) and mutant (G,H) embryos shows the presence of nerves in both cases. However, SC have been specifically lost from the distal part of the mutant nerves (black arrowhead in G,H). distal targets in both mutants (Fig. 4G,H) and controls (Fig. 4E,F). However, SC precursors (SCP; with β-galactosidase activity) covering the axons were very few in number or absent in the distal part of the developing subcutaneous or muscular innervations in the mutant embryos (Fig. 4G,H, arrowhead), in contrast to control embryos (Fig. 4E,F). Moreover, if we observed few SCP in the distal part of the spinal nerves, they were always associated with the axons, suggesting that the interactions of the SCP to their axons are not completely abolished by the removal of the β1-integrin. By contrast, on E16.5, SC were found at the apex of the nerves in the mutant embryos, as in controls (not shown). The transitory absence of SCP along axons may be due to a decrease in SCP proliferation or to an increase in the apoptosis of these cells. Because it is difficult to quantify the glial cells number along the spinal nerves and because SCP are mainly originating from the DRG, we analyzed the proliferation and apoptosis rate within that structure. No significant difference was observed in the percentage of proliferative DRG cells on E12.5 and E16.5 for control (30.69±0.88% and 14.07±3.34%) and mutant (33.17±4.04% and 19.78±1.89%) embryos, as shown by detection of the Ki67 marker. In addition, very few DRG cells expressed the activated cleaved caspase 3 apoptosis marker and the numbers of such cells were similar in both mutant and control embryos at these stages (not shown). These results could not account for the lack of SCP on E13.5 in the distal part of the developing PNS. We therefore conclude that this phenotype is probably related to a delayed migration of these cells along the axons. The subcutaneous nerve network at various sites, such as the area around the eyes, the lateral body wall and in the limbs, displayed similar morphological defects in all of the mutant embryos analyzed (n=13). At E13.5 and E14.5, the nerves in the mutants were always thinner and displayed a different pattern of arborisation from controls, as shown by whole-mount NF-160 immunostaining viewed from the ventral (Fig. 5A,C) and lateral (Fig. 5B-D and 5G-H) sides of the embryos and at the hindlimb level (Fig. 5E,F). In addition, the subcutaneous emergence sites of the sensory nerves always differed between the mutants and the controls (not shown). By contrast, at these stages, the extent of axonal growth was not significantly affected, even at the most distal part of the limbs in the mutants. β1-Integrin gene deletion causes a postnatal lethality Conditional disruption of the β1-integrin gene in migratory NCC and their derivatives did not result in the death of the embryo. All embryos reached term, as demonstrated by the Mendelian segregation of the two genotypes. Initially, no clear difference was detected between newborn control and mutant animals in terms of response to external stimuli (light or noise). All responded to tactile stimulation, but with the mutant animals displaying a weaker response (not shown). A few days after birth, the mutant animals began to display progressive defects in motor function, with the appearance of muscular weakness and muscular atrophy resulting in an abnormal posture (presented for P21 in Fig. 6A). The mutant animals were unable to climb on inclined surfaces and generally slipped on such surfaces. It was not possible to perform the Rotarod assay because the mutant animals were unable to hold on to the round bar and fell immediately. Mutant animals also put on body weight more slowly than did control animals (Fig. 6B). At birth, mutant and control animals (from five different litters) weighed a mean of 1.15±0.04 and 1.24±0.08 g, respectively, whereas after 3 weeks (P21) they weighed 6.07±1.01 and 11.45±0.52 g, respectively. This change in phenotype was observed consistently in the mutant animals of a given litters and in the various litters, with no difference in the response to the genetic change observed between male and female animals. Finally, the Ht-PA-Cre-dependent ablation of the β1-integrin gene led to the death of 90% of the mutant animals during the month after birth (Fig. 6C). The remaining 10% of mutant animals displayed no major defects, with only a mild motor coordination defect evident, and had a normal life expectancy. During embryogenesis, we found that all of the mutant embryos analyzed displayed defects in the trunk PNS development. Our observations indicated that the expressivity of the phenotype is stable because all the embryos exhibited similar abnormalities. In addition, the penetrance of the phenotype is high and the phenotype is severe because 90% of the mutant animals displayed a progressive impairment of posture and mobility after birth, and died during the first month. Myelination is known to begin just before birth. We assessed production of the major myelin structural protein, P0, in the sciatic nerves at birth and at three weeks. At P1, P0 was detected in the controls, confirming that myelination was occurring (Fig. 8B). By contrast, P0 was not detected in the sciatic nerves of mutants at this stage (Fig. 8D). At P21, P0 was detected in both controls and mutants and was found to be associated with the myelin sheaths (Fig. 8F-H, respectively). However, at this stage, there were clearly fewer P0-positive sheaths in the nerves of mutant animals than in those of the controls. Moreover, large patches of NF-160 immunoreactivity were observed in the sciatic nerves of P21 mutant animals (Fig. 8G). These results are consistent with the defect in neuron-glial segregation observed on semi-thin sections (Fig. 7D). In addition to the axo-glial segregation defect, loose basal lamina could be detected surrounding the myelinated axons as well as the clusters of unsorted axons at P21 (Fig. 7E). This suggests strong linkage alterations of these structures to the ECM. However, the axons within the clusters appeared not to contain basal lamina. Schwann cells are known to secrete various ECM proteins of which integrins represent the major receptors. We therefore assessed the expression level of major components of the ECM such as fibronectin, laminin, tenascin and collagen IV, in control and mutant sciatic nerves at P1 and P21 (Fig. 8I-R). At P1 and P21, laminin levels were lower in the sciatic nerves of mutants (Fig. 8N,O) than in controls (Fig. 8L). Fibronectin levels increased in controls between P1 and P21 (Fig. 8K,L), but decreased in mutants over this period, with fibronectin levels at P21 being lower in mutants than in controls, despite having been higher in the mutants on P1 (Fig. 8P,Q). Tenascin was not detected in the sciatic nerves of the two types of animals at P1. However, it was detected at P21, in larger amounts in the sciatic nerves of mutant animals than in those of controls (Fig. 8M,R). Collagen IV levels (not shown) were similar in the sciatic nerves of mutants and controls at both stages. Interestingly, at P21, some ECM-free spaces were detected in the mutant, reinforcing the idea that unsorted axons were not surrounded by a basal lamina as observed in Fig. 7E. In the mutants, the general organisation of the ECM was strongly disrupted at P1 and P21. This disruption was correlated with the delayed maturation of SC and changes in axo-glial segregation. **β1-Integrin loss in SC leads to neuromuscular innervation defects** The muscular activity is regulated by neuromuscular junction (NMJ) activity, which in turn requires coordinated interaction between SC, axons and muscle fibres (Burden, 1998; Sanes and Lichtman, 1999). We analysed the development of NMJs for various muscles obtained from P1 and P21 control animals and from mutant animals at P1 and from those at P21 that have developed motor and posture defects. Synaptophysin (synapto) and α-bungarotoxin (α-BTX) were used to detect the pre- (axonal terminal end) and post- (clusters of acetylcholine receptor, AChR) synaptic compartments of the synapse. The mutants differed from the controls in having a lower level of intramuscular innervation and in the formation of NMJs in abdominal muscles (Fig. 9) and the diaphragm, soleus and gastrocnemius muscles (not shown). At P1, the control abdominal muscle displayed a high density of AChR clusters co-localised with synaptophysin (Fig. 9A, inset), indicating the... apposition of the pre- and post-synaptic compartments, as previously described (Lin et al., 2001). At P21, fewer AChR clusters (Fig. 9C, inset) were detected, demonstrating that the known postnatal regulation of receptor number had occurred. By contrast, at P1, the muscles of mutants displayed high densities of AChR clusters, but most of these receptors were not connected to the post-synaptic apparatus (Fig. 9B, inset). At P21, the density of AChR clusters remained high in the mutant muscles, indicating that no postnatal regulation of receptor number had occurred. Some of these receptors were connected to nerve terminals (Fig. 9D, inset). The synapses in the P21 mutants appeared as ring-like structures (Fig. 9D, inset), resembling immature NMJs (Sanes and Lichtman, 1999). NF-160 immunostaining labelled a dense mat of nerve fibres, mostly restricted to the surface of the muscle in the mutants (Fig. 9F), whereas many nerve fibres aligned with the muscle fibres were labelled in the controls (Fig. 9E). NF-160 immunostaining also suggested the existence of aberrant connections at the point of arrival of the axon at the NMJ in mutant muscles compared to the controls (Fig. 9E,F, insets). However, SC, which is identified by S100 immunolabelling, were located along the nerves and, in particular, at the NMJs in the muscles of both the controls and the mutants (Fig. 9E,F, insets). Discussion The Ht-PA-Cre mouse strain is a useful tool for investigating the contribution of β1-integrins to PNS development. From E8, all the expected targeted cells, such as the glial and neuronal NCC-derivatives, lost the floxed β1-integrin gene in our conditional mutants, as shown by the recombination-dependent expression of the lacZ reporter gene. We found that the loss of β1-integrins in the NC-derived cells leads to severe defects in the PNS, with delayed migration of SCP along the axons, embryonic alterations of the peripheral nerve network, a delay in the start of myelination in sciatic nerves, a severe alteration in the radial sorting of sensory nerves and defective NMJ maturation. The diversity and severity of the mutant phenotype demonstrates the crucial direct and indirect roles of β1-integrins in establishing both the glial and neuronal components of the peripheral nerves. The early death of the mutant animals in the postnatal period is probably caused by respiratory failure resulting from extensive alterations of the PNS, together with multiple defects in enteric and neuroendocrine derivatives (M.A.B. and T.P., unpublished), and reveals the importance of β1-integrins in NCC ontogeny. β1-Integrins transiently control embryonic development of the cranial nerves The conditional deletion of the β1-integrin gene began in the cephalic region of the embryos at stage E8 and followed a rostral to caudal progression in line with the generation of NCC. On E10, in most mutants, significant changes were observed in the epibranchial ganglia and nerves, of NCC origin, with altered vagus nerve roots and also fusions of the IXth and Xth nerves. Interestingly, defects of this type are not observed in the trigeminal ganglia, despite the NCC origin of the glial and neuronal compartments (Pietri et al., 2003). These defects, observed during a period in which the loss of β1-integrins from the cell surface is incomplete, illustrate differences between the epibranchial ganglia and nerves and the trigeminal ganglia to integrin levels during development. Indeed β1-integrins were not lost immediately after recombination of the locus and ceased to be detectable at the 3879 β1-integrins in PNS development Fig. 8. Immunohistochemical analysis of sciatic nerves on P1 and P21. Transverse sections of sciatic nerves of control (A,B,E,F,I-M) and mutant (C,D,G,H,N-R) embryos on P1 (A-D,I,K,N,P) and P21 (E-H,J,L,M,O,Q,R). Immunolocalisation of NF-160 (A,C,E,G), the major myelin protein P0 (B,D,F,H), laminin (I,J,N,O), fibronectin (K,L,P,Q) and tenascin (M,R). The levels of labelling for different markers cannot be compared. Scale bars: in H, 25 μm for A-D and 50 μm for E-H; in R, 20 μm for I-R. cell surface only after 3 days of detectable β-galactosidase activity. This time lag to the loss of β1-integrins in the targeted structures limits the functional analysis of β1-integrin requirements during the early stages of NCC migration. In particular, no defects are observed in the branchial arches or in the colonisation of the heart in our mutants. A previous study showed that α4-integrin-null embryos die during early development and display abnormalities in heart development (Yang et al., 1995). In mouse and avian embryos, perturbation experiments with competitors have shown that α4-integrin controls cranial NCC migration (Kil et al., 1996; Kil et al., 1998). This suggests that, in our mutants, sufficient amounts of β1-integrins remain at the cell surface of the cranial NCC at these stages to support the correct development of these morphological processes. Consistent with this hypothesis, the elimination of β1-integrins earlier in development, when the NCC are still resident in the neural tube, results in the early death of the embryo (E12.5) (T.P., unpublished). In this case, the embryos die from haemorrhaging, accompanied by defects in NCC cardiac derivatives and in neural tube closure. Thus, various early morphological processes may occur if β1-integrins are expressed at the cell surface at low levels, but the complete loss of β1-integrins strongly inhibits these processes. An increase in the apoptosis of cephalic NCC has been described in α5-integrin-null mice (Goh et al., 1997). This phenomenon has not been observed in other knockout mouse models (reviewed by De Arcangelis and Georges-Labouesse, 2000; Sheppard, 2000). In our conditional mutants, the rate of apoptosis in the branchial arches was similar in mutants and controls (T.P., unpublished). This suggests that the increase in the rate of apoptosis observed in α5-null cranial NCC may be triggered by the combined effect of the loss of α5β1-integrin and a possibly defective ECM microenvironment in constitutive α5-integrin knockout embryos. The phenotypic effects on the cranial nerves of conditional mutants seem to be transient because on the following day, the cranial nerves and ganglia appeared similar to those of the controls. At birth, mutant and control embryos displayed no obvious differences in sensorial capacities, with both groups responding to external noise and light stimuli. This suggests the existence of a compensatory mechanism, operating after E10.5, establishing a new path to guide the altered nerve to its normal destination, leading to normal sensorial behaviour later on. Our results indicate that β1-integrins are not required for the further development and maintenance of craniofacial structures. β1-Integrins control embryonic development of the PNS In vitro studies have clearly implicated β1-integrins in the control of neurite outgrowth for peripheral neurons (Tomaselli et al., 1993; Ivins et al., 2000; Vogelezang et al., 2001). In our conditional β1-integrin knockout embryos, the loss of β1-integrins in sensory neurons does not affect their axonal growth. The general trajectory of the proximal portion of these nerves appeared to be minimally affected in the mutant animals, with the nerve endings reaching distal targets. However, the organisation of the network is visibly affected because, from E12, the distal region of the nerves of the body wall appeared less branched and fasciculated. In addition, the pathfinding of the distal region of the spinal nerves was perturbed, particularly when they reach the subcutaneous level. In addition to defects in nerve branching and fasciculation, we observed that the distal region of the nerves was not covered by migrating SCP, as shown by the lack of β-galactosidase-expressing cells along the nerve fibres at E12-13.5, in the mutants. This lack of SCP could give account into the developmental defect of the innervation network in mutants. Consistent with this hypothesis, similar embryonic PNS alterations in nerve branching and pathfinding have been described in the ErbB2, ErbB3, neuregulin 1 and Sox10 mutants (Erickson et al., 1997; Woldeyesus et al., 1999; Morris et al., 1999; Britsch et al., 2001; Riethmacher et al., 1997), which display alterations in the development of NCC derivatives and lack SC. For example, in ErbB2 mutants in which the heart development defect has been rescued by the myocardial-dependent expression of ErbB2, the cutaneous sensory nerves display normal overall trajectories but are free of SC precursors, poorly fasciculated and disorganised (Woldeyesus et al., 1999; Morris et al., 1999). Taken together, these and our results strongly suggest that migratory SCP are required for correct organisation of the innervation network and nerve morphology. The α4β1- and α5β1-integrins have been implicated in control of the survival and proliferation rates of SC obtained from explants of embryos lacking α4- and α5-integrins (Haack and Hynes, 2001). The SCP migrating along nerves are originated from the DRG. However, we detected no difference in the proliferation or apoptosis rates of the β1-null NCC derivatives in the DRG of our mutants at E12.5 or E16.5. In addition, the lack of SCP along nerves was transient because, by E16.5, as for the controls, SCs were detected in the distal region of the spinal nerves in mutants. Although we cannot exclude the possibility that a modification of proliferative or apoptosis rate may occur on SCP located along the nerves, the loss of β1-integrins (which is effectively complete by this stage) seems to reduce the rate of migration of the SC along. Fig. 9. Innervation profile of muscles of controls and mutants. Whole-mount preparation of abdominal muscle of control (A,C,E) and mutant (B,D,F) animals on P1 (A,B) and P21 (C-F). The presynaptic compartment is visualised by immunolocalisation of synaptophysin (Synapto) and of the postsynaptic compartment with α-bungarotoxin (α-BTX), which reveals clusters of AChR. SC are labelled for S100. Each inset shows a higher magnification of the corresponding panel, making it possible to focus on the structure of NMJ. nerves. This is consistent with previous observations showing that SC lacking β1-integrins survive and proliferate normally in vivo (Feltri et al., 2002). As spatiotemporal regulation of the integrin repertoire occurs during SC ontogeny (Bronner-Fraser et al., 1992; Stewart et al., 1997; Milner et al., 1997; Previtali et al., 2001) other integrins, such as α6β4, αVβ3 and αVβ8, may have compensated for the possible migratory defect of SC induced by the loss of β1-integrins, by E16.5 in the mutants. **β1-Integrins are required for radial sorting of the sensory axons in sciatic nerves** In the course of development of peripheral nerves, cytoplasmic processes of promyelinating SC penetrate into the axon bundles to progressively achieve a one to one ratio between SC and axons. This phenomenon, starting just before birth, is named radial sorting and precedes the myelination process (Mirsy et al., 2002). In the mutant, the radial sorting of motor axons (not targeted by the mutation) occurs and the subsequent myelination of motor axon-associated SC is not affected. By contrast, there was an almost complete absence of myelinated sensory axons (distinguishable by β-galactosidase activity). Sensory axons remain in large dense clusters of unsorted axons, indicating that a defect in axo-glial segregation occurs in the mutant nerves. Alterations in the radial sorting and myelination process have been described in P0-Cre;β1fl mutants (Feltri et al., 2002), where postnatal nerves were composed of numerous clusters of unsorted axons and of few myelinated fibres. In the P0-Cre;β1fl mutants, the conditional disruption of the β1-integrin gene is restricted to the glial lineage; the SC are targeted between E13.5 and E14.5 and the loss of the integrin subunit on these cells is achieved by E17.5, whereas the neuronal components of the sciatic nerve are not targeted. Therefore, in this study the phenotype appears to be SC autonomous. The authors attributed the partial loss of myelinated axons in the adult sciatic nerve as the result of a random escape process because of compensation by others receptors. In the Ht-PA-Cre;β1fl mutants, the conditional mutation is made on SC and in sensory neurons early during development, and we can visualize the targeted cells by their β-galactosidase activity. The defects obtained on radial sorting of the Ht-PA-Cre;β1fl mutant sciatic nerves are in agreement with a crucial role of β1-integrins in SC to achieve the axo-glial segregation. We are able to discriminate the sensory axons from the motor axons within the sciatic nerves. This has allowed us to show a much more prominent defect of radial sorting on the sensory compartment than on the motor compartment. This observation suggests that the β1-integrins in neurons could be also required for this process. In addition, the absence of myelinated sensory axons indicates that the myelination process requires the β1-integrin functions both in SC and neurons. However, in the P0-Cre;β1fl mutants (Feltri et al., 2002) the discrimination between the sensory and motor axons could not be made and it was not possible to determine whether the radial sorting defects affected only one or both types of neuronal fibres within the sciatic nerve. Therefore, it is possible that in the P0-Cre;β1fl mutants, as for the Ht-PA-Cre;β1fl mutants, the radial sorting defect is restricted to the sensory compartment. In this case, additional hypotheses can explain the differential response of sensory and motor compartment of the sciatic nerves to the inactivation of the β1-integrin gene: (1) owing to their distinct embryonic origin, sensory and motor neurons may express different sets of cell adhesion molecules involved in the radial sorting process such that the sensory axon sorting mechanism required β1-integrins on glia; and (2) SC could be specialized in two distinct types, each ensheathing only motor axons or only sensory axons, and with distinct requirement for β1-integrin function. To definitively conclude on the specific role of β1-integrins in neurons and SC during the development of the PNS, it would be interesting to compare the radial sorting process of sensory and motor axons in animals in which the invalidation of β1-integrin gene is restricted to SC, to motor or sensory neurons, or to both SC and neuronal compartments. The delay in the myelination of SC in the Ht-PA-Cre;β1fl sciatic nerves is consistent with results of two other studies that have implicated β1-integrins in the control of the myelination process. One of these studies shows that β1-integrin blocking antibodies prevent SC co-cultured with DRG neurons to myelinate the sensory axons (Fernandez-Valle et al., 1994). Another study shows that glial cells that have been genetically modified to express dominant negative forms of the β1-integrins, were unable to remyelinate after their transplantation in the dorsal funiculus (Relvas et al., 2001). In addition, several lines of evidence demonstrate that laminins and their receptors are involved in PNS development and that SC require contacts both with the basal lamina and with axons for their survival and maturation during development (reviewed by Jessen and Mirsky, 1999; Previtali et al., 2001; Previtali et al., 2003; Mirsky et al., 2002). These interactions facilitate the activation of the signalling pathways mediated by various molecules including the focal adhesion kinase and paxillin (Chen et al., 2000) (reviewed by Previtali et al., 2001), further implicating β1-integrins in the initiation of myelination. These observations are consistent with our observation that myelination was delayed in mutant sciatic nerves. Together with changes to the ECM in the sciatic nerves, the general delay in myelination in mutants strongly suggests that the loss of β1-integrins alters the interaction of the SC with the basal lamina, as previously suggested (Feltri et al., 2002), and with axons. In addition, the loss of β1-integrins in targeted cells appears also to affect the ECM and basal lamina organisation. The presence of a basal lamina surrounding unsorted axons in the Ht-PA-Cre;β1fl mutant sciatic nerves is consistent with a retraction of SC cytoplasmic processes and previous reports for several types of peripheral demyelinating neuropathies (reviewed by Dyck et al., 1992). This similarity is corroborated by quantitative modifications of the ECM, in particular tenascin deposition in the sciatic nerves on P21, and indicates that demyelination may occur in the mutants. The absence of basal lamina surrounding the unsorted axons within the clusters in the mutant sciatic nerves at P21, strongly suggests that the SC did not individually ensheathe those axons in earlier stages of the maturation of the nerves. Therefore, our data strongly indicate that both processes – complete absence and retraction of SC cytoplasmic process – may occur concomitantly in the mutant sciatic nerve. **β1-Integrins are required in the terminal SC for the targeting of nerves and maturation of the neuromuscular junctions** The defects in intramuscular innervation observed in several muscles at birth and following postnatal stages in the mutant animals suggest that SC with β1-integrins are required for axonal target selection. It was recently suggested that glial cells may be involved in this process in Drosophila (Poeck et al., 2001), but no similar mechanism has yet been described in mammals. By contrast to control animals, in which axons penetrated the muscle to innervate specific fascicles, most of the nerve network in the mutants remained along the surface of each muscle layer and failed to penetrate. On stages P1 and P21 in the mutant animals, SC covered the entire length of the motor nerves from base to tip and were found at the nerve endings. This suggests that β1-integrins are required for the interactions of SC with axons or basal lamina and to facilitate the entry of axons into the muscle layers and the targeting of AChR clusters. The perturbation of intramuscular innervation was more apparent on P21 than on P1 in the mutant animals, indicating the lack of a compensatory mechanism. At the postsynaptic level, on P1, no difference was observed in the number and structure of AChR clusters in the mutants, indicating that this failure for the axons to meet the targets was not due to the absence of targets. The mismatch between nerve endings and AChR clusters (pre- and post-synaptic compartments, respectively) was striking on both P1 and P21, confirming the independence of the formation of AChR clusters from the presynaptic apparatus. The mutants responded to tactile stimulation at P1, which implies that there were some functioning NMJs at that stage. However this ability to respond deteriorated thereafter, suggesting that SC and sensory innervation were involved in this process. Even in the presence of the three components of the synapse (axons, terminal SC and postsynaptic apparatus), NMJ observed at P21 in the mutant resemble to an immature NMJ as they have a ring-like structure. This type of structures is normally observed in the normal course of NJM development from P7 to P10 (Burden, 1998; Sanes and Lichtman, 1999). In addition, a lack of regulation of the number AChR clusters in the mutant occurred, at least until P21. In wild-type rodents, this mechanism occurred within the first 2 weeks after birth. Therefore, NMJ maturation in the mutants appears to be blocked at an early stage of their postnatal development. Several studies examining muscle re-innervations have suggested that terminal SC are involved in the maintenance and remodelling of the synapse (Son and Thompson, 1995). Our results point out the β1-integrins as major receptors for the proper activity of the terminal SC in the course of the NMJ development. In normal NMJ development (reviewed by Sanes and Lichtman, 1999) or after nerve regeneration (Rich and Lichtman, 1989), a significant number of synapses are eliminated during organisation of the nerve-muscle connection. Synapse elimination involves the withdrawal of the axons and SC processes. This process was observed in the control animals, in which the number of AChR clusters and nerve terminals in the abdominal muscles decreased from P1 to P21. By contrast, in the mutants, the number of AChR clusters increased from P1 to P21. This phenomenon resembles the responses of muscles to denervation, by increasing the number of AChR clusters (Blondet et al., 1989). The increase in the number of AChR clusters in mutants coincides with progressive muscle fibre atrophy, reflecting the absence of stimulatory innervation. This suggests that the failure of many axons to establish functional NMJs leads to muscle to produce more AChR clusters and that the process of synapse elimination is probably not initiated. The specific alteration of the elaboration and maturation of the NMJs in our mutant animals shows a SC autonomic effect for the muscular innervation and reveals the major involvement of the β1-integrin specifically in the terminal SC functions. We conclude from our results that β1-integrins are important for correct interactions between glial cells and axons, SC migration, axon morphology and the organisation of spinal nerves into networks en route to their peripheral targets. This study also highlights the functions of β1-integrins for both the neuronal and glial lineages of the PNS and at several steps in the differentiation of peripheral nerves, such as radial sorting and myelination, as well as the muscular synaptogenesis. The anti-160 kDa neurofilament (clone 2H3) antibody was obtained from the Developmental Studies Hybridoma Bank, developed under the auspices of the NICHD and maintained by the Department of Biological Sciences, University of Iowa, Iowa City, IA 52242. We thank the staff of the animal facilities at the Institut Curie. We thank Daniel Meur, Dominique Morineau for their help in imaging, and Daniele Tenza for her help and advice in electron microscopy. We also thank Juan J. Archelos and James A. Weston for generously providing us with antibodies. We also thank Matthew Morgan for his careful reading of the manuscript and helpful suggestions. This work was supported by the Centre National de la Recherche Scientifique, the Institut Curie and the Association pour la Recherche sur le Cancer (grant number 5653). T.P. was supported by fellowships from the Fondation pour la Recherche Médicale and the Association pour la Recherche sur le Cancer. References β1-integrins in PNS development 883
Applying Behavior Trees to StarCraft AI DAT5, FALL SEMESTER 2010 GROUP D518A DEPARTMENT OF COMPUTER SCIENCE AALBORG UNIVERSITY 22ND OF DECEMBER 2010 Diagram: - Harass enemy - Attack enemies in sight - Enemy in sight? - Move to enemy - Timer - Attack Enemy - Move In Range - Enemy in range? - Retreat Title: Applying Behavior Trees to StarCraft AI Theme: Artificial Intelligence in RTS games Project period: Dat5, fall semester 2010 Project group: d518a Group members: Søren Larsen Jonas Groth Kenneth Sejrsgaard-Jacobsen Torkil Olsen Long Huy Phan Supervisor: Yifeng Zeng Abstract: We investigate the area of game AI with focus on the video game genre of Real-Time Strategy using StarCraft as test platform. We proceed to discuss different AI methods that have an application in RTS games. We choose to focus on behavior trees and present our implementation of a behavior tree framework, for implementing behavior trees, and an editor for designing them. We test the framework by implementing a set of behaviors described in the report and finally conclude on the work done by proposing new possibilities for further development. Copies: 7 Number of pages: 70 Appendices: 2 Completion date: 22nd of December, 2010 The contents of this report are openly available, but publication (with reference to the source) is only allowed with the agreement of the authors. Additional material available on the attached CD. Preface In this report we discuss the aspects of constructing an artificial intelligence (AI) for a computer game that can provide the human opponent with an entertaining challenge, rather than showing off super-human intelligence and decision making. Several aspects are important for this area, such as the techniques used to create the AI, the performance of the AI, the computer game genre the AI is intended for and so forth. We will describe some of the game mechanics of the selected game, StarCraft, but the reader is required to have some basic knowledge of StarCraft such as the units and structures etc. In Chapter 1 we discuss the different types of video game genres and select a genre that we want to further investigate. We proceed to discuss key aspects of this genre and select a game for which we want to develop an AI for. Chapter 2 gives a more in depth description of StarCraft and the game mechanics. We also define the scenario we will be using in the rest of the report. In Chapter 3 we introduce different methods for creating game AI. We also briefly comment on other AI methods, such as learning and planning. We end the chapter by summarizing the discussed methods and select one method for further use in the report. Chapter 4 describes the framework and editor, for designing and implementing behavior trees, developed as part of the report. In Chapter 5 we propose a set of behavior trees that make up a simple StarCraft AI. The behavior trees are implemented in the designed framework and tested in Chapter 6. Finally we conclude our work and propose possibilities for further work in Chapter 7 and Chapter 8. The framework and the editor are available for testing on the CD enclosed with this report or by request from the authors. We would like to thank deathknight13579 and lowerlogic for providing the BWAPI framework used for implementing AI’s in StarCraft and dpershouse for providing bwapi-mono-bridge and responding to issues with his implementation. # Contents 1 Introduction ......................................................... 1 1.1 Video Games .................................................. 1 1.2 Strategy games ............................................. 3 1.3 Video Game Environment for This Project .................... 4 1.4 Project Purpose ............................................ 4 2 StarCraft: Brood War .................................................. 5 2.1 Game Aspects .................................................. 5 2.2 Game Mechanics ............................................. 7 2.3 Full Game Scenario ......................................... 7 2.4 Scenario .................................................... 8 2.5 Brood War Application Programming Interface ............. 9 3 AI Methods .......................................................... 11 3.1 Scripting ..................................................... 12 3.2 Finite State Machines ....................................... 14 3.3 Behavior Trees .............................................. 18 3.4 Additional Methods ......................................... 22 3.5 Evaluation .................................................. 25 4 Framework and Editor .............................................. 27 4.1 Framework .................................................. 27 4.2 Editor ....................................................... 36 5 Case Study .......................................................... 40 5.1 Behavior Tree: Strategy ..................................... 40 5.2 Behavior Tree: Attack and Scout ............................ 41 5.3 Behavior Tree: Harass ....................................... 44 5.4 Behavior Tree: All In ....................................... 46 5.5 Behavior Tree: Defend ...................................... 47 5.6 Behavior Tree: Multiple attacks ............................ 48 6 Test ................................................................. 50 6.1 Test: Attack and Scout ...................................... 50 6.2 Test: All In .................................................. 51 ## CONTENTS 6.3 Test: Harass Attack ................................................. 51 6.4 Test: Defend ......................................................... 52 6.5 Test: Multiple Attack ............................................... 52 7 Improving Framework and Editor .......................... 54 7.1 Framework Improvements .................................. 54 7.2 Editor Improvements ......................................... 55 8 Conclusion ............................................................... 57 8.1 Further Work .................................................. 58 A Classdiagram ......................................................... 59 B Execution Flow ....................................................... 60 Bibliography ........................................................... 61 Video games offer a great platform for AI development. Depending on the genre of video game it may vary which method to use when designing the AI. Before going into details in a specific game and AI methods we will give an introduction to the video game domain by describing and discussing the genres video games are generally categorized by. Then we will narrow it down to a more specific branch in the strategy game genre and briefly introduce the game chosen in this project. 1.1 Video Games There exist a tremendous amount of video games. Each of these games can be put into one category or a hybrid of multiple categories. The categories have different game aspects in focus, for instance adventure games rely a lot on the story while action games rely more on fast paced action. In this section we will present the most commonly known genres in video games and discuss their key features. Action Action games are typically characterized by being fast paced and require the player to have quick reflexes and good accuracy to win the game. The action game category has several sub-categories such as beat-em ups and shooters. Both sub-categories are action games but provide the player with very different experiences. In beat-em up's the object is to fight your opponent(s), typically in an arena using melee weapons or hand-to-hand combat. The first player that loses all his or her hit points loses the game. Amongst widely known titles in this sub-genre are Tekken [17], Mortal Combat [15] and Dead or Alive [24]. Shooters are different in the sense that you take the role of a character that needs to eliminate a lot of enemies while finding some path to a goal location or complete a mission. These games often offer a huge arsenal of weapons ranging from melee weapons to ranged weapons like pistols, machine guns and rocket launchers. The most popular ways of interacting with shooter games are by first or third person gaming. In first-person shooters your view is defined by where the avatar is looking. In third-person shooters your view is defined as a point somewhere behind the avatar effectively looking over his or her shoulder. Role-Playing Role-playing games are often based on one or more avatars who through questing, combat, puzzle solving, monster slaying etc. can gain experience and increase in level. At each level the avatars can improve their skills usually selected by the player. The primary source of entertainment for the player is seeing and affecting the way the avatar(s) progress through the game as well as being immersed in the storyline. Many role-playing games incorporate some kind of adventure game aspects, which will be explained below, and a story or primary mission for the player to complete in order to complete the game. Role-playing games often implement some notion of good vs. bad for example in the form of karma. Karma determines how non-playable characters (NPCs) in the game perceive the avatar(s). This forces the player to give decisions additional consideration as every decision has an impact on the rest of the game. ### Adventure Adventure games primarily present the player with riddles and puzzles that the player has to solve in order to progress in the game. There is always a main goal or storyline in the game that is reached through successfully solving the riddles and puzzles. An old but still popular example of adventure game, are the games of the Monkey Island series [11]. In this series the player is presented with one major goal at the beginning of the game and then through smaller chapters, sub goals are completed, in order to reach the final goal. A significant part of this specific series is the oddness of the riddles. The player will often be presented with very illogical problems requiring illogical solutions. ### Strategy The strategy genre revolves around the player making strategic and tactical decisions in order to win a game. The core of most strategy games is warfare and the strategic and tactical decisions revolve around the player training the correct units to counter the opponent units while seizing control of the map. Some strategy games revolve around a more global and realistic scenario. Here the player can be presented with both military, political, economic and research problems that need to be solved in order to complete the goals of the game. ### Simulation The simulation genre is based on making a game as realistic as possible. Probably the commonly best known type of simulation games are the flight simulators. These games are designed to teach the player how to pilot a plane by having realistic cockpits and flight conditions, and letting the player take off, maneuver and land the plane on the ground again. Some simulation games revolve around making some business or company run and grow. This would require the player to make decisions about expanding operations and making use of supply and demand to increase revenue of the players company. ### Summary We have decided to focus on a game from the strategy genre. The primary reason for this is the obvious application area for an AI. Strategy games rely on strategic and tactical decision which often require some clever reasoning. We have also chosen the strategy genre because the remaining genres do not offer the same possibilities in AI development as the strategy genre. For example in adventure games there is no real need for an AI to act as the player as the game is most likely predetermined. 1.2 Strategy games For years, the genre of strategy video games has been popular among gamers all over the world. The reason for this may very well be the fact that strategy games encourage the use of strategic and tactical thinking. However there is a major difference between some games in the genre that has lead to the definition of two subsets of strategy games, namely Real-Time Strategy (RTS) and Turn-Based Strategy (TBS). 1.2.1 Turn-Based Strategy The most defining characteristic in Turn-Based Strategy (TBS) games is the fact that each round each player has one turn to perform his or her actions. Actions can consist of moving or attacking with military units, selecting new research, setting up a building queue for a town etc. When all players have finished their turn the round ends and a new round begins. As one would imagine TBS games can be long running. The turn-based game play also has an impact on the creation of an artificial intelligence to provide an entertaining challenge for a human player. This, due to the fact, that when the AI would get its turn and that the length of the turn being, theoretically unlimited, the AI could perform more complex calculations and use more complex models for the game to determine the course of action. Many people know the series of TBS games, Civilization [14] created by Sid Meier. This series features turn-based game play with a strong AI and a lot of features that need to be used strategically to win the game. These features include diplomacy, keeping your civilization happy and researching new technology etc. 1.2.2 Real-Time Strategy Opposed to TBS games are Real-Time Strategy (RTS) games. These games are more action-oriented and tactical and strategic decisions need to be made on the fly while the opponent(s) may be attacking you. Most RTS games have relatively short game time compared to TBS games, but pride themselves on being more realistic due to the fast paced action packed nature of the games. This real-time fast paced game play puts an obvious limit on the AI that can be used in the game. The AI cannot be too complex as the calculations and models need to be computationally light, or else the AI will not be able to make decisions in due time as actions become obsolete if not executed when required. The challenge with RTS AI is creating an intelligent solution that does provide an entertaining challenge to the human player and uses relatively few resources. 1.3 Video Game Environment for This Project A classic in the RTS genre, and the focus of this project, is StarCraft: Brood War [2]. This game features a fast paced action game of resource management and strategic decision making along with tactical management of military units. Having been on the market over a decade, with a huge community sharing their thoughts and opinions of the game with the Blizzard Entertainment development team, has resulted in a stream of updates and patches to tailor the game to be very balanced. This means that out of the three playable races, there is no one more powerful than the others. StarCraft: Brood War is a complex game to play. It involves actions being performed at multiple scales as players have to make economic, strategic and tactical decisions alongside reacting to the opponent. All this is done on the fly due to the game being an RTS game. With the game having fog of war and thus being partially observable, it often comes down to mind games. This means that it is possible to keep your opponent in the dark while you execute some strategy and surprise attack him, but if not done with care or not having eyes open on the opponent, he can surprise you or spot your strategy and make it obsolete. The Brood War Application Programming Interface (BWAPI) enables the development of custom AIs for StarCraft: Brood War with relative ease. The BWAPI will be further explained in Section 2.5. All this combined along with our own interest in the game makes StarCraft: Brood War the obvious choice of game and a very interesting environment for developing an AI and studying it. We will go into more details on StarCraft: Brood War in Chapter 2. 1.4 Project Purpose The main goals of this project are as follows: - Give an in depth description of StarCraft: Brood War to pinpoint the challenges in developing an AI for the game and create a game scenario to be used for case studies. - Discuss viable AI methods for creating RTS game AI and present a survey of applying the different AI methods to StarCraft: Brood War. With the purpose of finding the pros and cons of the different methods. - Present possibilities for future work and improvements. StarCraft: Brood War is a real-time strategy game developed by Blizzard Entertainment. The game was released in 1998 and later that year Blizzard Entertainment released StarCraft: Brood War, an expansion to the game which brought several game play improvements including new units, maps, campaigns and balancing changes. From this point forward will we refer to StarCraft: Brood War as StarCraft. The Setting StarCraft is set in a science fiction universe created by Blizzard Entertainment. The location is the distant Koprulu Sector of the galaxy where three powerful races fight for supremacy and survival. StarCraft offers three playable races. The Terran, human outlaws exiled from earth. Protoss, the proud and highly intelligent race of their home planet Aiur. Finally the Zerg, monstrous creatures who seek only to destroy. Every unit in StarCraft is unique to its respective race. The technologically advanced Protoss are known for their expensive but strong units. They rely on the quality of each unit over their numbers. The Zerg on the other hand have inexpensive but rather weak units. Their power lie in their numbers. The Terran units are more balanced regarding price and strength. 2.1 Game Aspects The competencies for succeeding in the game are often categorized into macro management and micro management. Macro management includes the big decisions, like which initial strategy to use, which units to get, when to attack, moving armies across the map etc. Micro management is when individual units are given specific orders. The major aspects of StarCraft will be described in the following sections. Resource Management Resources are needed in order to construct buildings, train units and research upgrades. In StarCraft there are two kind of resources, minerals and vespene gas. Minerals can be mined right of the mineral patches by workers but in order to get vespene gas a gas extractor has to be built on the vespene geysers which workers then can extract gas from. Throughout the game players need to sustain a consistent income to ensure unit training, research and base construction when needed. The workers gathering resources are the lifeline of each players progress in the game. Therefore, it is critical to protect the resource line from enemy attacks, as the loss of even a few workers will cripple the economy and result in a major set back in training military units. 2.1 Game Aspects **Base Construction** Base construction includes which building to construct and where to place them. Which buildings chosen affects which units are possible to train and the placement of building is also important as it is possible to block some entry point to your base. The three races all have diverse and unique buildings and way of construction. The Zerg base appears as one living organism and the buildings are able to heal themselves slowly over time. Some buildings spread a carpet of biomass called creep and most new buildings may only be built on the creep. The Zerg workers sacrifice themselves in the process of building structures as they do not construct the structures but rather evolve into buildings themselves. Protoss buildings are not constructed but warped in from the Protoss home planet. The workers only need to start the warp in and are then free to perform other commands. The majority of Protoss buildings require psi power in order to be warped in. The building known as a pylon emits psi power around itself. In this radius new buildings can be warped in and the finished buildings need the psi power to continue operation. Unlike the other two races, the Terran have no restriction to where they can place buildings. Some of the Terran buildings can lift off and fly to a new location. When constructing a building one worker attends the construction site until it is finished and is vulnerable to attacks. A weakness of the Terran construction is when a building takes a certain amount of damage it will catch fire and if not repaired by a worker it will eventually burn to the ground. **Scouting** The partial observability of the game makes scouting and map awareness an essential part of the game. The players only see what their own units and buildings have vision of, so in order to see what the opponent is planning they have to send some units to do reconnaissance. It is important to scout to see what your opponent is doing so that you can take counter measures. For instance if your opponent is training flying units or units capable of cloaking, you need some anti-air units or detector units. Scouting is also the only source of information gain in the game. By scouting your opponent early in the game you can expose his strategies and if he for example is doing a rush strategy, where he attacks very early, appropriate countermeasures can be taken. **Combat** Combat in StarCraft includes several aspects. They range from selecting appropriate units to counter your opponent’s units, timing of attacks and controlling individual units in combat. The controlling of individual units is often referred to as micro management. One specific technique called *dancing* is when the player orders a unit to attack, while the weapon is reloading the unit moves back to avoid damage and then in again to shoot. 2.2 Game Mechanics All aspects of the game are cut in stone and there are close to no random factors. This means that the outcome of a game depends solely on the players playing it and their skill. For instance the outcome of a battle between two equal forces of military units depends only on how the players control their units and not on any varying damage or probability factors. Other RTS games have chance elements like ranging damage, critical hits (probability of increased damage), evasion and dodge (chance of avoiding attacks) and also a unit armor decrease incoming damage by some percentage. None of these elements exist in StarCraft. For example the marine in StarCraft has a starting damage of six. This can be upgraded three times giving +one damage each time. Said unit will always deal this damage, no more no less. The unit taking the damage may have some armor value. Say it has a armor value of two, then all incoming damage will be decreased by two leaving a non-upgraded marine deal four damage each shot. There is although one thing that has an effect on damage in StarCraft and this is the size of a unit. Units in StarCraft are either small, medium or large. Building are considered large. The size of a unit is taken into account when calculating the effects of different classes of damage. The damage classes and their effectiveness in relation to the three unit sizes are as follows: - Normal weapons are equally effective against all types of units. - Concussion/Plasma weapons do 50% damage against Medium units and 25% against Large units. - Explosive weapons do 50% damage against Small units and 75% against Medium units. The Scenario used in this project will only include one type of unit, which is of small size, and hence always does full damage. These damage calculations will therefore not be discussed further. Although not existing as unit abilities, StarCraft has the terrain determined property of a unit being on high ground. Units attacking enemy units who are on higher ground have a chance to miss on attack. As our scenario will not allow units being on high ground this element is considered not relevant for the time being. This section is based on the information from the StarCraft Compendium [4]. 2.3 Full Game Scenario A full game scenario of StarCraft provides all players with a base and a few workers at the start of the game. Players build and expand their base, train units and ultimately eliminate all opposing players. The players keep in mind all the aforementioned elements as the game progresses. They plan their strategies and switch to new strategies if they see the opponent do something unanticipated which affects the current strategy. Challenges To summarize, the challenges in playing a game of StarCraft are many. First of all an initial strategy must be chosen. This strategy will be executed until successfully defeating the opponent or be replaced by a new strategy if your opponent’s strategy is resistant to your current strategy. Furthermore you have to scout your opponent to see what he is doing and ideally keep some pressure on him by attacking his resource gatherers. All this, alongside defending yourself from your opponent doing exactly the same to you, poses several interesting challenges. ## 2.4 Scenario The scenario that we will use as a test bed for our approach is a simplified subset of a full game of StarCraft. The goal is to capture the important aspect of a full game and still keep it as simple as possible. ![Figure 2.1: A map illustrating our scenario. There are three attack routes, some obstacles and two HQs.](image) Our scenario, which is depicted in Figure 2.1, consists of a small squared map with two players. Each player will have a HQ in opposite corners of the map, that is at the bottom left and top right of the map. Every ten seconds a marine will spawn close to the HQ. The map is designed in such a way that there are three attack paths, top, mid and bottom. The goal of the players is to destroy their opponent’s HQ and by doing this they win the game. The purpose of having units spawn at time intervals rather than having a building training units at the cost of resources is for simplification of the scenario. By doing this we can disregard the base building and resource management aspect of the game and focus solely strategic and tactical decisions. The map design with only three paths also adds to the simplicity of the scenario. The challenges to face in this scenario are the following: - Should one launch an attack on one path with full force or split up the army and attacks several fronts 2.5 Brood War Application Programming Interface For the implementation we will be using Brood War Application Programming Interface (BWAPI) [6]. BWAPI is a free open source C++ framework for developing custom AIs for StarCraft: Brood War. BWAPI uses DLL injection. The required software for using the BWAPI is StarCraft Brood War 1.16.1, an Integrated Development Environment (IDE) appropriate for the chosen programming language, Microsoft Windows and due to BWAPI using DLL injections a loader is needed to enable the BWAPI injections to be loaded into the StarCraft process. Although BWAPI being an interface written in C++ there exists a wide range of wrappers and proxy bot implementation. With proxy bot the AI bot is running in a remote process and communicates with the AI module on top of the BWAPI through sockets. Wrappers and proxy bot allow the programmers to write AI behavior in different programming languages than C++. With BWAPI it is possible to query the game state for relevant information on every game frame. Methods for retrieving game information include methods being queried on individual units to get their type, position, health status, upgrades, etc. and methods for querying players in the game for information like amount of resources, get a list of all their units, supplies used, etc. Furthermore there are methods for retrieving information on the specific map being played. For instance mineral fields, vespene geysers, etc. Supplementing the built in terrain methods in the BWAPI there exists an add-on for BWAPI called Brood War Terrain Analyzer (BWTA) which analyzes the map being played and returns all possible base locations, choke points and regions. In addition to methods for retrieving game information there are methods in the BWAPI for issuing orders to specific units. These orders include move, attack, build and train commands as well as using unit abilities etc. There are also methods for querying specific units for their current status for instance one can check whether a unit is a worker with the isWorker method. Furthermore the methods isIdle, isMoving, isGatheringMinerals, isCarryingMinerals, isAttacking, isBeingConstructed, which are self explanatory, grant the programmer great control over the units and their status. Every unit and entity in the game has a position on the map specified as an x and y coordinate. A map of size 64x64 in StarCraft consists of 64 position tiles time 64 position tiles. Each position tile consists of 32x32 positions and these positions define the x and y coordinates of units. Tile positions and positions are used depending on the orders to issue, for instance when constructing buildings tile positions are used and positions can be used to move units. This fine resolution of the map gives a fine grained control of units. BWAPI works by triggering methods on certain events in the game. Also there is a method that is fired on every frame of the game. Examples of game events are onStart, onEnd, onSendText, onUnitShow, onUnitHide, onUnitCreate and onUnitDestroy. OnSendText can be used by the programmer to trigger some AI behavior or set some game options, like game speed or cheat flags, while the game is running. In BWAPI there are two cheat flags accessible, enable full map information and enable user input. These are great for debugging purposes, but are of course not allowed in official games. If full map information is enabled then all units on the map are fully accessible to the BWAPI meaning that all information on the unit are accessible. With the flag disabled then units owned by the BWAPI player remain fully accessible, but the enemy units fall in the categories normal, partial and no accessibility. Normal accessibility is when a unit is detected and visible. The information available includes all of the attributes in full accessibility except some specific attributes like what a building is producing, how much time left on the production or the quantity of a units items etc. Partial accessibility is for cloaked units that are visible, but not detected. The onUnitHide and onUnitShow events are triggered when units transition between partial and no accessibility. Units hidden by the fog of war or dead units fall in the category no accessibility. We will be using the bwapi-mono-bridge for implementing the AI [7]. It is a wrapper implementation that exposes the BWAPI functionality to the .NET framework through Mono. This makes it possible to do the implementation in a .NET language of our choice which is C#. Bwapi-mono-bridge implements two solutions, one that embeds the AI bot in the same process as StarCraft and one that runs in a separate process and communicates as client/server. We will be using the client/server solution in order separate the AI and game execution. When run in the same process space they can interfere with one another for instance if there is a computationally expensive task in the AI, it can slow down the game if run in same process. AI is quickly becoming a larger part of computer game development today. With graphics approaching photorealism, the next big improvement is the AI experience. However, there are several issues one must deal with when developing game AI. First off, games today are often very complex with respect to the size of the game world and the realism demanded of NPCs. If one were to consider the entire state space of a modern game, including the different actions and positions of the NPCs, it would be impossible to apply any of the traditional academic AI methods. To address this problem, developers will often have to simplify the state space of the game. However, this often results in a simplified AI which could reduce the game experience, as players today demand even more realistic behavior from the AI. The representation of the game must thus be simple enough for the AI to process it in real-time, and still complex enough to produce a believable behavior. Another problem one must address is the scope of game AI. When working with academic AI one will often try to reach a level where the AI can be considered super-human. That is, it is superior to a human with respect to the particular problem for which it was developed. In game AI we never want to reach a super-human level of AI. An AI who can defeat the human player every time will drastically reduce the game experience to the point where the player forfeits. As a game developer it is in ones interest to create an AI which poses a certain challenge for the player, but is still capable of mistakes resulting in defeat. There are several different approaches to game AI capable of dealing with the above mentioned problems to some extent. Two of these approaches are scripting and Finite State Machines (FSM). Each of these approaches have their own pros and cons and depending on the game scenario it has been up to the programmers and designers of the game AI to find a compromise. In the next sections we will describe the general principles of these two approaches to game AI, namely scripting and FSMs, and a third approach Behavior Trees (BT). The methods will be described, discussed and evaluated in relation to the scenario proposed in Section 2.4. A discussion of different AI techniques such as learning and planning will also be included, to make grounds for further improvements of the methods evaluated. 3.1 Scripting When developing AI for computer games the speed of execution is of considerable importance. Depending on the type of game an AI should typically make decisions within a time window of a few game frames. It is therefore of no use developing sophisticated and complex AIs if they are not capable of executing in real-time. Another factor is the amount of work it takes for a development team to develop an AI. Typically the AI is a very complicated part of the game and may take months of developing time. Furthermore, due to the complexity of AIs, it often demands the attention of skilled programmers; programmers who are already working on many other aspects of the game. For this reason, it is in every game company’s interest to reduce this development time and ease the strain on their programmers. The best way to achieve this would be to put some of the work on other parts of the development team, mainly game designers. To do, this the process of developing AIs would have to be simplified. It is due to these demands that scripting has become the most popular method for developing computer game AI. While being very efficient compared to advanced AI methods, it is also quite easy to learn. Usually scripting is done in a scripting language, which is always very high level and thus accessible. The high level constructs also reduces the time it takes to write scripts, as more instructions take up fewer lines compared to lower level languages. It has also become quite popular for game companies to develop their own scripting languages for their games. By doing this they can ensure that it only contains the constructs and functions relevant for a particular game. Often, such languages are accompanied by tools providing GUI-based editors for the language. One such tool is Blizzard’s StarCraft 2 Editor [3], the world editor for StarCraft 2. This editor implements Galaxy, a scripting language developed by Blizzard Entertainment, and makes scripting easily accessible for everyone, even the end users. Example This section will give an example of scripting applied to a small part of our StarCraft scenario. Although we could have used the editor of the original StarCraft game, we feel that this would result in an unfair assessment of scripting, since that editor is more than a decade old. Instead, we will show how scripting can done today, using the StarCraft 2 Editor to demonstrate the script of a similar scenario. Figure [3.3] illustrates a harassing behavior of a single unit, created in the StarCraft 2 Editor’s trigger editor, and show how scripting can be done without the need to manually write the code. 3.1 Scripting Figure 3.1: The StarCraft 2 Editor’s trigger editor A behavior similar to the one in Figure 3.1 is shown in Listing 3.1 just to illustrate how the code of a written script could look like. Parts of the code have been omitted and replaced with comments to reduce the number of lines of code. ``` 1 def HarassEnemy() 2 Unit nearestEnemy = getNearestEnemy() 3 while nearestEnemy.getDistance() > 6 do 4 # move to nearest enemy 5 end 6 if nearestEnemy.getDistance() <= 6 then 7 # attack enemy for one second 8 end 9 end 10 # move away from enemy 11 end ``` Listing 3.1: Guard behavior on unit sighted event. Assume that both of these scripts are set to execute when the unit is created on the map. First it will find the nearest enemy unit and, if outside its range, start moving towards it. At every given interval the script will check whether the enemy unit is within range of its weapon. When this condition is satisfied it will attack the enemy unit for one second and then start moving away from it. Both of these scripts do roughly the same, but what is important to note, is that every variable, condition and action used in the script in Figure 3.1 have been created just by clicking through the various options offered by the GUI. With tools such as this, scripting has been simplified to the point where programmers need only to create the tool. Afterwards the playable parts of the game can be created in the editor without help from programmers. Furthermore, scripts such as these are interpreted by the game engine and do not need to be compiled with the game. This allow for developers to change the scripts and view the changes without re-compiling the entire game. It also allows end users to write their own scripts for the game once released and create their own AI. 3.1.1 Summary Scripts have been and still are the more popular approach to AI development, and with good reason. Much effort is put into developing scripting languages and tools to assist developers and designers creating even more realistic AI in shorter time. Especially tools such as the StarCraft 2 Editor show just how powerful and efficient scripting can be, and that the use of the method is far from declining. Other than the ease of use, scripts are also an efficient methods when it comes to computation time compared to advanced AI techniques. However, scripting has a limited functionality, as the complexity of scripts quickly increase with the complexity of the behavior. This can result in scripts becoming incomprehensible to game designers who may not have the necessary programming experience. 3.2 Finite State Machines FMSs are regarded as one of the simplest approaches to NPC behavior in games. FSMs have been widely applied especially to first-person shooters [1], but also other game genres such as RPGs and RTS games [16]. The reason for FSMs being so popular is their ease of use as humans find the concept of ‘being in a state’ comprehensible. With FSMs game designers can design the behavior of NPCs with close to no knowledge about programming. In this section we will discuss the structure of FSMs and Hierarchical Finite State Machines (HFSMs). We will then show an example of how HFSMs can be applied to a small part of the StarCraft scenario. Concluding the section, the pros and cons of FSMs compared to other methods will be discussed. 3.2 Finite State Machines 3.2.1 Structure The definition of an FSM can be seen in Definition 3.1. **Definition 3.1 – Finite State Machine** An FSM can be defined as a quintuple \((Q, \Sigma, \delta, q_0, F)\) where - \(Q\) is a finite, non-empty set of states - \(\Sigma\) is a finite set of inputs - \(\delta: Q \times \Sigma \rightarrow Q\) is the state-transition function - \(q_0\) is an initial state s.t. \(q_0 \in Q\) - \(F \subset Q\) is the set of accept states Visually the FSM can be represented as a directed graph with states and transitions, both illustrated in Figure 3.2. ![Figure 3.2: Illustration of a state and a transition arc.](image) When applied to game AI each of the states represent some behavior or an action of an object. \(\Sigma\) will be the set of events or conditions in the game which can trigger a transition from one state to another. An example of this is given in Figure 3.3. ![Figure 3.3: Two simple finite state machines based on either behaviors (a) or actions (b).](image) We observe two FSMs which both model a unit standing guard. The unit will stand guard as long as it does not spot an enemy. Depending on how the unit is modeled the sighting of an enemy will either trigger an event or change a condition according to Figure 3.3. With each iteration of a game, events will be observed and conditions will be updated. Considering Figure 3.3a if at some point the event **Enemy sighted** is fired, it triggers the transition function \(\delta(\text{Guarding}, \text{Enemy sighted}) = \text{Aggressive}\). As a result of this transition function the behavior of the unit will change to **Aggressive**. In a simple scenario such as this, we can assume that Figure 3.3b would represent roughly the same behavior. When the condition EnemyInSight? becomes true, the unit will execute the Attack action. The difference between the two FSMs in figure 3.3 is that Figure 3.3a implements the attack action as part of its aggressive behavior, whereas the FSM in Figure 3.3b executes the attack action as a direct result of the condition. If states are used to represent behavior, the states implement all the actions relevant to the behavior and are responsible for executing the entire behavior. When using FSMs to design computer game AI, both approaches can be applied and both have their pros and cons. Using behavior will often provide a better overview with fewer states and transitions, but requires more lines of code in each state. On the other hand, if every state represents a single action, the number of states and transitions can become quite numerous. It is to the programmers and designers to decide upon which approach to use. ### 3.2.2 Hierarchical Finite State Machines Even though FSMs are often adequate to describe the behavior of a game character the number of states and transitions often present a problem. When the complexity of a game increases the number of states and transitions between these will rapidly increase. It quickly becomes very difficult for the game designers to keep track of the different states and their transitions. Thus working with regular FSMs in larger games is tedious work to say the least. An extension of FSMs, HFSMs [5], addresses some of these problems. This model introduces the concept of modularity by allowing groups of states to share transitions. The purpose of this is to avoid redundant transitions and get a better overview of the model. Using HFSMs it also becomes easier to group action states to form behaviors. An example of this is illustrated in Figure 3.4. ![Diagram of a HFSM modeling a guard unit](image) **Figure 3.4:** Illustration of a HFSM modeling a guard unit. This illustration is a modification of the FSMs from Figure 3.3. The Stand Guard and Patrol actions have been grouped together to form the more general Guarding behavior super state. This grouping should be understood s.t. whenever an enemy unit is sighted from any state in the Guarding super state, it triggers the Enemy sighted event and changes behavior to Aggressive. In short, there is a transition from both Stand Guard and Patrol to Aggressive. We could have modeled the Aggressive behavior state in the same way, including the actions and tran- 3.2 Finite State Machines sitions necessary to model an aggressive unit. By doing this, events that causes a unit to abandon the aggressive behavior, will need only one transition from the Aggressive super state, instead of one from each of the inner states. 3.2.3 Example To show how HFSMs can be applied to our scenario in StarCraft, we have illustrated a small harass behavior in Figure 3.5. The scenario assumes that we have a unit standing idle awaiting orders. ![Figure 3.5: Illustration of a HFSM modeling a harass behavior in StarCraft.](image) If the unit does not have a target it will transition to the Move To Nearest Enemy Group super state. In this state there are two actions Get Nearest Group and Move In Range. Both can transition to the Attack state if the Target In Range event is triggered. The Attack state is contained in the more general Harass Attack super state, which specifies that a harass attack behavior is characterized by attacking an enemy unit for one second and then moving away from it. This very simple HFSM illustrates how unit behavior in StarCraft can be expressed, and is only meant to give insight as how a potential behavior could be modeled. It should be clear to the reader, that more complex behavior would result in a quite big HFSM with many more states and transitions. 3.2.4 Summary The HFSM model is a great improvement over the FSM model, as it greatly reduces the number of transition arcs and allow for a better overview of the behavior. The comprehensibility of the method is also of great help to the game designers, who might not have expert knowledge on programming. Still, when dealing with complex AI, the number of states and transitions can become quite extensive, resulting in an opaque model structure. This also poses a problem if parts of a behavior need to be changed, as it can be difficult to see through the consequences it might have in other parts of the behavior. Furthermore, to even consider HFSMs, the behavior must be easily decomposable in order to divide it into different states. This can be rather difficult with more complex behavior. On the other hand, behavior may also become too simple with the risk of states becoming visible to the player. This will end up shattering the illusion of intelligence and may decrease the players game experience. All in all, HFSMs provides a very intuitive framework for dealing with transitions between behaviors, but at the cost of being less flexible. 3.3 Behavior Trees The concept of a BTs is a relatively new approach to behavior design. BTs combine elements from both scripting and HFSMs to provide a flexible framework, usable by both game designers and programmers, with as little complexity as possible. The structure of BTs are also meant to provide a more scalable approach than HFSMs, by reducing structural complexity. BTs have already been used in some recent games, including Halo 2 [10], Halo 3 [8] and Spore [9]. This indicates that the method is not only applicable in theory, but also in practice. Our investigation suggests that the typical use for BTs in commercial games is mainly for modelling NPC behavior. So far, we have not seen any examples of BTs in RTS games, which means that further investigation is needed to confirm whether it is a viable solution. In this section we will define the syntax and semantics of BTs. This will be followed by an example based on a small part of the StarCraft scenario specified in Section 2.4. Concluding the section will be a comparison of the previously mentioned methods. 3.3.1 Syntax The syntax, we have chosen for the BTs described in this project is based on [23] with some modifications. A BT is a tree structure with a single root node specifying the beginning of the tree. The root node can only have one child, which can either be a non-leaf node or a leaf node. All other node constructs can only have one parent. The non-leaf nodes, which are illustrated in Figure 3.6, must each have any finite number of children, with the exception of the root node and decorator node which must have exactly one child. These non-leaf nodes can be viewed as tasks to be performed. Each task is defined by a subtree consisting of the different elements that make up the task. There are two basic non-leaf nodes that act as complements of each other. These are the selectors and sequences. Furthermore, there are decorators, which can be used to provide more functionality to the BT and parallels which adds concurrency. The leaf nodes, illustrated in Figure 3.7 in a BT specify an observation or interactions with the game environment. These leaf nodes are called conditions, actions and links. Leaf nodes are often viewed as elementary actions and should be as concise as possible. 3.3 Behavior Trees ![Figure 3.7: Illustration of leaf nodes in a BT.](image) ### 3.3.2 Semantics The execution of a BT is done depth-first, starting with the root node. Usually, all non-leaf nodes will execute their children from left to right, but there are exceptions. When a node has finished executing, it returns a status which can either be success, failure or exception. The circumstances under which success or failure is returned, depend on the node type. Exception is returned in the case that something went wrong and the node was unable to produce either a success or failure. **Selector** The selector node will sequentially try to execute its child nodes from left to right until it receives a successful response. When a successful response is received it responds to its parent with a success. If a child node responds with a failure, the selector node executes the next child node in line. If all child nodes respond with failure the selector node itself responds with a failure. **Probability Selector** A probability selector is a selector node with a probability distribution over its children. The probability indicates how likely a child is to be chosen during execution. If the child node chosen responds with a failure it will normalize the probability distribution over the remaining children and choose a new child to be executed. It responds to its parent in the same way as a normal selector node. **Sequence** The sequence node will execute each of its child nodes in sequence from left to right until a failure is received. If every child node responds with a success the sequence node itself will respond with a success to its parent. If somewhere during the sequence of execution, a child node responds with a failure, the sequence node will respond with a failure. **Decorator** The decorator node can be added to the BT to provide even more flexibility. A decorator is essentially a construct that allows for additional behavior to be added without modifying existing code. Decorators are most commonly used as filters with conditions such as, execute once, execute with some probability, etc. Besides filtering, a decorator can be used for pretty much any behavior modification the developer can think of. In contrast to selector nodes and sequence nodes, decorators only have one child node. 3.3 Behavior Trees A decorator returns success if the specified conditions are met and its subtree has been executed successfully, otherwise it returns with a failure. A decorator which produces a failure will not execute its subtree. **Parallel node** A parallel node is a node, which concurrently executes all of its children. The circumstances under which a parallel node should return success or failure is up to the programmer. It could be that the parallel node is only successful if all its children are successful, like the sequence node, or it could behave like a selector node, only waiting for one successful child. **Condition** Conditions are nodes that will observe the state of the game environment and respond with either a success or a failure based on the observation. This could be a value comparison, a condition check, etc. **Action** Actions are nodes that are used to interact with the game environment. Through actions we can control various aspects of a game character such as movement and interaction with objects. When actions are performed successfully, the action node will respond with a success. If the character fails to perform the action, the action node will respond with a failure. An action should be as simple as possible and often represent single actions in the game world. Even though an action could be programmed to represent an entire behavior itself, this would be bad practice as it would neglect the entire use of the BT structure. **Link Node** A link node holds a link to the root of another BT. When a link node is executed it will execute the linked BT and wait for a response. If the linked BT is successfully executed, it will respond with success, otherwise it will respond with failure. This introduces modularity and reusability of behaviors. ### 3.3.3 Black Board During the execution of a BT it is often necessary to store information obtained from action nodes or condition nodes at run time. Such information could be coordinates, names, probabilities, etc. Storing such information enables one to obtain data in some part of the tree and store that data for later use. To store this information we introduce the black board. The black board is basically a construct that stores whatever information is written on it. We allow for the black board to be public such that any node inside or outside the tree can read to and write on it. The reason is, that we want a mechanism for sharing data between BTs. The black board is meant to provide more freedom to the designer, but at the same time it demands more responsibility. The information stored on the black board must be meaningful both in regards to naming 3.3 Behavior Trees and context in which it is meant to be used. If used the wrong way it will quickly become difficult to maintain. 3.3.4 Example We illustrate, in Figure 3.8, how a BT can be applied to a simple harass behavior of a unit in StarCraft. ![Behavior Tree Diagram] *Figure 3.8: An illustration of a simple harass behavior modeled as a BT.* When this BT is executed the root node will run its child, the Harass mid selector node. This will execute the left-most side of the tree first, starting with the Hit and run sequence and then the Enemy visible? condition. This condition will check whether an enemy is visible somewhere in their path. If this is the case it will produce a success and the sequence will move on to the Range selector, which checks whether the visible enemy is inside range of the unit’s weapons. If this is not the case, it will execute the action node and move the units to the nearest enemy group. When inside range, a timer decorator will execute the **Attack nearest enemy** action for at most one second. At last the **Repeat until success** decorator will execute the **Retreat** sequence, causing the units to move back as long as the enemies are visible. In case the **Hit and run** sequence fails, the **Harass mid** selector will execute the **Move to enemy HQ** action, sending the units towards the enemy’s headquarter. This all illustrates how a BT can be used to create a harass behavior in a simple way. Provided with a proper GUI, the creation and editing of this tree would be a very simple task. ### 3.3.5 Summary BTs provide an intuitive and comprehensible framework that can easily be applied to a game scenario. The structure and semantics of BTs make it easy to follow the flow of the behavior, which is useful for both understanding, modifying and debugging of existing behavior. The basic constructs provided by the framework makes adding or removing parts of a behavior a simple task, and the modularity it provides scales well as the behaviors grow in size. Another great construct when dealing with the problems of scalability and reusability is the link node. By dividing smaller behaviors into BTs of their own, one can keep overview of a larger behavior by combining smaller sub-behaviors via link nodes. As with HFSMs, one still has to maintain an overview of the structure and identify the individual parts of the behavior to decompose it into the tree structure. For this reason BTs may exhibit some of the same issues as HFSMs, where parts of the tree may become apparent to the player, thus shattering the illusion of intelligence. ### 3.4 Additional Methods The preceding discussion on AI methods applicable to StarCraft only cover methods able to exhibit behavior that is completely static. Static in the sense that everything the AI is able to do has to be predefined and precoded. In order to give an evaluation on these methods and their limitations, the following covers a brief introduction on planning and learning so that a comparison between these methods and the ones already discussed is possible. #### 3.4.1 Planning The notion of planning can be described as the following: Given an initial state and a goal state, we wish to obtain or reach, construct a sequence of actions that enables us to reach the goal state. This simplified notion of planning is what we also refer to as **Classical Planning** \[21\]. In classical planning the states are represented by atoms, or rather, conjunction of atoms. Atoms being relations optionally followed by a set of parameters, where the atom is true if the relation holds between the terms given as parameters. Actions are not directly represented as simple functions on the environment, but are instead described by action schemas. Action schemas define both actions and the effects of these actions. That is, when selecting an action for a plan, we know the corresponding effect of that action, where the effect is the resulting new state. A set of preconditions for the action is also included in the action schema. The action can only be taken if these preconditions hold true. The problem of actually planning a sequence of actions can be viewed as a search problem. Starting in the initial state we can simply search the state space by traversing available actions from state to state until a goal state is reached. Because of the declarative representation of action schemas there are two possible ways to do this; forward search from the initial state and backward search from the goal state. During execution of the plan, re-planning can be utilized if unexpected states are reached as a result of following the plan. This introduces some overhead, because a new plan has to be computed. Depending on the planning problem at hand, the state space can become so large that simple search becomes unfeasible. To overcome this problem a heuristic function is employed. With the basics of planning described, two different extensions to classical planning will be discussed. Hierarchical Task Networks Like classical planning, *Hierarchical Task Network* (HTN) planning use the notion of conjunctive atoms to represent states and action schemas to describe actions. However, compared to classical planning, we do not plan to achieve a goal, but instead perform some set of *tasks*. A task is defined as one or more composites of sequential ordered actions or tasks. Each task holds a prescription of the distinct sequences it can be decomposed into. HTN planning is the process of recursively decomposing these tasks until only a sequence of actions are left \[12\]. Actions which can be performed by an agent following the plan. HTN planners take great advantage of the available knowledge on how tasks may be decomposed. That is, whenever we encounter a task for which a plan has already been constructed through decomposition, we may reuse that plan instead of having to search for a plan. This can greatly reduce the computational time spent searching for new plans. HTN planners are also able to expand existing knowledge with new decompositions of tasks. This knowledge base is sometimes referred to as a *plan library*. The strength of a plan library is also one of the reasons why HTN planning has been more widely used for practical applications compared to other planning methods. Game AI developers are for instance able to predefine decomposition of high level tasks so that the AI acts as expected when encountering certain tasks. On the other hand the game AI is able to construct behavior on its own for loosely defined tasks. HTN planning has among other games been used in the first-person shooter *Killzone 2* \[20\]. Goal Oriented Action Planning *Goal Oriented Action Planning* (GOAP) is an extension to *STRIPS* (acronym for STanford Research Institute Problem Solver) which in terms is analogous to classical planning 1. The GOAP extension was proposed by Jeff Orkin from the M.I.T. Media Lab with the motivation being to develop the A.I. for Monolith Productions first-person shooter *F.E.A.R.* \[18\]. GOAP has since been used in other games and game genres, e.g. the RTS game *Empire Total War* \[19\]. The notion of GOAP adds several extensions to STRIPS. The most important of these extensions are, including costs to actions and adding procedural preconditions and effects to the action schemas. The cost of actions can be used as a heuristic when searching the state space for plans. --- 1The Planning Domain Definition Language (PDDL) used to formulate the planning problems in classical planning is a minor extension to the STRIPS planning language. 3.4 Additional Methods STRIPS and classical planning is limited in the action precondition in the sense that states can only be recognized by a conjunction of atoms. Adding procedural preconditions extends the formal view of the world, and allows additional filtering on states. The last extension covered here is adding procedural effects to action schemas. Recall that action schemas also describe the effects of taking an action. The declarative nature of these effects imposes instantaneous change to the state when taking an action. In real world scenarios actions are not necessarily instantaneous and instead take some amount of time to execute. Remember from Section 3.2 that FSM states are procedural compared to the declarative states of planning. In GOAP both these notions of states are used. The time element is implemented by connecting the planning system with FSMs. When taking an action in GOAP the procedural effects set the FSM state until the action is completed and the world is transitioned to a new declarative state. 3.4.2 Reinforcement Learning Reinforcement learning can be described as learning which actions should be taken in an environment in order to maximize or minimize some cumulative reinforcement or reward [13]. However, reinforcement learning is not defined by a specific method to achieve this learning process. It is instead defined as characterizing a set of problems which we refer to as reinforcement learning problems. Any method that help solve this problem are referred to as a reinforcement learning method. The reinforcement learning problem in general can be visualized by Figure 3.9. Here we have an agent who interacts with an environment by some actions $a$. Each action leads to some change in the environment represented to the agent as states, $s$. The information about the environment represented in the states is dependent on the observability of the environment to the agent. It is required that this environment is at least partially observable to the agent. ![Figure 3.9: Interaction between agent and environment in reinforcement learning.](image) Changes in the environment may induce some reward $r$ to the agent, both negative or positive. This reward is given by the reinforcement function which maps pairs of states and action to rewards. The learning part of the problem is deciding the state and action pairs that result in the maximum or minimum cumulative reward until some terminal state is reached. The reward of an agent’s actions may not be immediate, but instead depend on the reinforcement learning scenario at hand. Also, the goal of whether to maximize or minimize the cumulative reward also depends on the scenario. In the following we will however assume that the given scenario require us to maximize the reward. Consider the game Backgammon, where the configuration of the playing board would be represented as states, and the legal moves represented as available actions. Positive reward would be given only in terminal states corresponding to a win, and negative reward in terminal states corresponding to a loss. Any other states would give zero reward. This is referred to as pure delayed reward. Given the reinforcement function for a reinforcement learning problem, how does the agent learn which state and action pairs are optimal? In the following, a policy determines which action should be taken in each state. To indicate how good a given state is, we will refer to it's value as the cumulative reward obtained when starting in that state and following a fixed policy to a terminal state. A value function describes a mapping from states to such values. Finding the optimal value function is the key problem of reinforcement learning, because with this, starting in any state we will know not only that state’s value but also all reachable states' values through the available actions. Simply taking actions that result in states with maximum, equals having followed the optimal policy. In this way the cumulative reward or reinforcement will be maximized, as was the goal of reinforcement learning. Finding the optimal value function is difficult, and usually done through approximation by dynamic programming. 3.5 Evaluation In this chapter we have described and discussed several methods and techniques for AI design in a computer game scenario. Two of these methods, scripting and HFSMs, are widely applied in the game industry today. The last method, BTs, is a recently proposed method, which has been applied to a few games in the last few years. It is also worth noting, that we have found no material on BTs being used in RTS games. This suggest, that it has yet to be tested whether BTs are actually usable in this game genre. Of the three methods we evaluated, scripting is the most commonly used for creating behavior in games. Scripting provides a simple solution for creating AIs, given little experience with programming. In the last couple of years there has been an increase in the number of tools, which allow for scripting via GUI- based editors, thus making delegation of behavior design an easier job for non-seasoned programmers and game designers. FSMs have also been used for many years, mainly for NPC behavior, but have also been proven to work well in RTS game scenarios. FSMs provide a comprehensible framework for designers, but is not very flexible and does not allow for reusability of logic. This results in a design with an increasing number of duplicate states making it unnecessarily complex. The issue of increased design complexity has been addressed in HFSMs by introducing super states, but the method still suffers from lack of reusability and duplicate states. BTs have been introduced to make up for the lack of reusability in HFSMs, by letting each node encapcu- late its own logic. By doing this, a node will contain some behavior based on itself and its children. This behavior can be seen as independent from the rest of the context and can be reused where it is needed. This particular feature makes BTs very scalable compared to HFSMs and creating complex behaviors will be less tedious. All of the three methods evaluated share some common flaws. Behavior created by scripting, HFSMs or BTs will react according to a predefined behavior. None of the methods provide any technique for learning by mistakes or planning ahead. As such the behavior will be somewhat static, as something unpredicted can never occur. Though the player may come to think of the AI as being intelligent, it 3.5 Evaluation is only an illusion of intelligence. If the player were to see through the model, he could easily take countermeasures resulting in a sure victory. To gain some ideas for improvement of these methods, we chose to look at some techniques from the field of classic AI, namely planning and learning. Our intention was to identify the strengths of these techniques and use these as inspiration for future work. Planning is shown to be very relevant when considering human-like behavior in games. Human-like behavior in general relies greatly on planning ahead, not only when playing games, but in everyday life. For this reason planning fits nicely with the concept of strategic thinking required in RTS games. Where we set up some goals and plan a way to reach them. In comparison, scripting, FSMs and BTs rely on reactive planning. That is, they only plan the next action to be taken based on the current context of the world. Planning has already been proven feasible in RTS games, as GOAP has been applied to Empire Total War. As such, it could be interesting to see how planning would fare in a fast paced RTS game like StarCraft. Learning, as planning, is also essential when looking at the behavior of humans. When performing tasks we obtain experience, either by success or failure, and that experience is recalled next time we have to perform a similar task. We have discussed reinforcement learning as a technique, and described how it can be applied to a simple game of backgammon. This approach however, will try to find the optimal sequence of actions to reach a terminal state. To incorporate this in an RTS game, the reward received for an action would have to be defined in a way s.t. the sequence of actions does not result in super-human behavior. Instead the reward should be based on the gameplay experience, which is the variable we want to maximize. This is perhaps the greatest challenge of inducing learning in a game such as StarCraft, as gameplay experience is a difficult measurement to define. In the end we have chosen to focus on BTs, as it is a fairly new method which, we believe, holds a lot of potential. Also, the apparent lack of use of BTs in RTS games, provides us with further challenges, as it could prove to be infeasible. If BTs prove to be applicable and efficient in an RTS game scenario, the study of planning and learning may inspire further improvements of the method, hopefully pushing towards more human-like behavior in StarCraft. To support the construction and use of BTs we need an editor to create the structure of the tree and a framework that can be used to implement the structure and utilize the BWAPI. Given that BTs have only recently been adopted by the game industry for AI design, the availability of existing frameworks and editors for BT implementation is very limited. The open source C# project TreeSharp only includes a subset of the node constructs that BTs offer, and only offers the framework, not an editor. Another open source project, also developed in C#, called Brainiac Designer offers both a framework and a designer to utilize the framework. As with TreeSharp, this solution only includes a subset of the node constructs. GameBrains is a recently released BT middleware framework and editor, and is written in C++. It is available as open source, but currently only as a beta test agreement. Because of this, we have developed our own graphical editor and framework supporting all the node constructs in BTs. In this way the framework and editor can be optimized for use with the BWAPI. In this chapter we will describe the approach used to create these two tools by giving an overview of the tools. We will explain the more complex parts of the tools in detail to give a better understanding. The framework has been implemented in C# using .NET 3.5 and the editor has been implemented in Windows Presentation Foundation (WPF). ### 4.1 Framework In this section we describe the developed framework to use when implementing behaviors in games. As described, the framework has been implemented in C# and .NET and as such it requires the intended game to expose an API that can be used in C# and .NET. The BWAPI is, as described in Section 2.5 implemented in C++, which does not directly expose the API to C# and .NET. However, as we also described in Section 2.5 the bwapi-mono-bridge framework exposes the C++ API to the Mono framework. As the Mono framework is interoperable with .NET, the C++ API is available in C# through Mono. We will provide an overview of all classes in the framework and show specific complexities in more detail where we deem it necessary. The full class diagram can be seen in Appendix A. <table> <thead> <tr> <th>BlackBoard</th> </tr> </thead> <tbody> <tr> <td>+blackBoard : Dictionary&lt;string, Dictionary&lt;string, object&gt;&gt;</td> </tr> <tr> <td>+NewBehaviorTreeBlackBoard(ind name : string) : string</td> </tr> <tr> <td>+GetBlackBoardKeys(ind blackBoardName : string) : &lt;uspecificeret&gt;</td> </tr> <tr> <td>+GetBlackBoard(ind i) : &lt;uspecificeret&gt;</td> </tr> <tr> <td>+WriteValueOnBlackBoard(ind blackboardName : string, ind valueName : string, ind value : object) : void</td> </tr> <tr> <td>+GetValueFromBlackBoard(ind blackboardName : string, ind valueName : string) : object</td> </tr> <tr> <td>+EraseValueFromBlackBoard(ind blackboardName : string, ind valueName : string) : void</td> </tr> <tr> <td>+EraseBlackBoard(ind blackBoardName : string) : void</td> </tr> </tbody> </table> **Figure 4.1:** BlackBoard class 4.1 Framework 4.1.1 Auxilliary Classes BlackBoard The BlackBoard class shown Figure 4.1 provides a common place for all BTs to communicate. Each BT will on creation get a spot on the blackboard. All BTs can read from and write to all other BT’s blackboards thus creating the ability to communicate information between trees. The blackboard is implemented as a dictionary of dictionaries. Each BT gets a dictionary in the outer dictionary with its name as the key and the inner dictionary as the value. The inner dictionary consists of string keys and object values. This allows the designer to store all kinds of information on the blackboard under a given string name. This of course demands some responsibility from the designer as he or she will need to keep track of what is written where on the blackboard. <table> <thead> <tr> <th>BehaviourTree</th> </tr> </thead> <tbody> <tr> <td>- root : Node</td> </tr> <tr> <td>- sync : BTBarrier</td> </tr> <tr> <td>- result : bool</td> </tr> <tr> <td>- separateThread : bool</td> </tr> <tr> <td>- name : string</td> </tr> </tbody> </table> +BehaviorTree(ind name : string, ind root : Node) | +SeparateThread(ind bar : BTBarrier) : void | +CloseBehaviorTree() : void | +Execute() : bool | +Name() : string | +GetSync() : BTBarrier | +SetSync(ind bar : BTBarrier) : void | +Result() : bool | *Figure 4.2: BehaviorTree class* BehaviorTreeThreadWrapper The BehaviorTreeThreadWrapper class seen in Figure 4.3 encapsulates the threaded execution of a BT in an easy to use class. The wrapper is instantiated with a tree and it creates a new barrier and a new thread for use in the execution. This barrier is then set in the tree and all of its nodes. The new thread is given the private Run method which calls the execute method on the tree. The wrapper exposes three methods for execution; Start, Continue and End. The Start method starts the execution thread and waits for it to reach the first node that requires it to wait at the barrier. Once the barrier is reached the Start method returns. It is now up to the designer to repeatedly call the Continue method for as long as necessary. The Continue will signal the barrier and allow the BT to continue execution. If the tree has not yet completed its execution, the Continue method will wait for it to complete or reach the barrier again. If the BT has completed execution and the Continue method is called nothing will happen. If the tree needs to be re-executed, the Restart can be called which resets the tree and restarts the thread. The End method attempts to join the execution thread so that the execution can be completed. 4.1 Framework **Figure 4.3:** BTBarrier class **BTBarrier** Due to the fact that the Mono does not implement .NET 4.0 completely it was necessary to implement a simple version of the *Barrier* class (Figure 4.3) from .NET 4.0. This is done by using two counters, one for counting the total number of participants and one for counting the number of participants not yet at the barrier. Once a thread reaches the barrier it signals the barrier and waits. The wait is done using the *Monitor* object from *System.Threading* in .NET. If the number of remaining participants is greater than 0 the thread waits and if there are no remaining participants all threads are pulsed and resume execution. **4.1.2 Behavior Tree-Specific Classes** **BehaviorTree** The BT class depicted in Figure 4.2 is in itself quite simple. It contains a *Node* object as its root node and a name of the BT to allow for retrieval of the correct spot on the blackboard. The BT also contains a reference to the active barrier in the tree execution. This barrier will be explained later. When the barrier is set, in a *BehaviorTree* object, the method pushes the same barrier onto the root node which in turn will apply it to any children it may have. The Behavior Tree class also contains a method to allow execution in a thread separate from the creating and executing thread. With this in hand the calling thread can continue execution while the tree runs its actions. The execution of the tree in a separate thread is made easier when using the *BehaviorTreeThreadWrapper* class described above. **Figure 4.4:** BehaviorTreeThreadWrapper class 4.1 Framework Nodes As described in the previous chapters BTs have several different types of nodes and they all have a specific semantic regarding their execution. Below is a description of each of the nodes available in our framework. <table> <thead> <tr> <th>Node</th> </tr> </thead> <tbody> <tr> <td>- sync : BTBarrier</td> </tr> <tr> <td>- parentTree : BehaviourTree</td> </tr> <tr> <td>+ Execute() : bool</td> </tr> <tr> <td>+ GetSync() : BTBarrier</td> </tr> <tr> <td>+ SetSync(ind bar : BTBarrier) : void</td> </tr> <tr> <td>+ GetParentTree() : BehaviourTree</td> </tr> <tr> <td>+ SetParentTree(ind tree : BehaviourTree) : void</td> </tr> </tbody> </table> Figure 4.5: Node class Node Node is the main class given in Figure 4.5. All types of nodes are descendants from this class. The class is abstract and as such each descendant must implement all abstract methods defined in this class. The class also specifies methods for how to propagate the barrier object and the parent BT object to its children if there are any. The Node class specifies that each descendant must implement the Execute method which is used to execute the BT. LeafNode We have split nodes into two groups. The first group is LeafNode depicted in Figure 4.6. This class is abstract and serves as a way of splitting nodes that can have children from those that cannot. All descendants of LeafNode must not have children. Action The Action class is the class representing the action node in a BT. This class is abstract as the action nodes require details about the available actions in the game API. As such, programmers and game designers must create new descendants of Action that implement specific actions in the game environment. Condition As with action nodes condition nodes are also not possible to define before the game API is known. For this reason the *Condition* class is abstract. Again it is necessary for the programmers and game designers to implement conditions that use information from the game environment to determine if the result is true or false. Link The link node of a BT is implemented in the *Link* class. A link node contains a link to another BT that must be executed in the link node. The result of the link node is based on the result of the tree it calls. When the *Execute* method is called on a *Link* object the *Execute* method of the tree it references is called and the execution of that tree is started. ![Diagram of NonLeafNode classes](image) **Figure 4.7:** NonLeafNode classes NonLeafNode The other group of nodes in our framework are the non-leaf nodes illustrated in Figure 4.7. These are represented with the class *NonLeafNode*. Descendants from this class are allowed to have children. Decorator The decorator node is, as described previously, a node that can add functionality, not available through the other nodes, to the tree. We cannot define a generic way for a decorator to be implemented as this both depends on the game API and on the feature that it implements. The class is abstract and the programmer and game designer must define how their decorators work and implement it accordingly. It is required that decorators must be non-leaf nodes and as such are required to have one child. 4.1 Framework **Sequence** A sequence node is implemented in a generic way through the *Sequence* class. This class executes all of its children one after another until either one of the children fails or all children have succeeded. This implements the exact semantic of the node as previously defined. **Parallel** The parallel nodes are used for executing several branches of a BT simultaneously. As the success or failure of a parallel node is hard to define we have chosen to implement three different types of parallel nodes, each with their own demands for successful termination. **AParallel** The *AParallel* class implements a version of the parallel node where the requirement for successful termination of the node is given by the successful termination of all parallel branches. This means that all branches must succeed for the *AParallel* to succeed. **MParallel** The *MParallel* class relies on a certain number of branches to succeed in order for the node to succeed. When instantiating the node a minimum number of successful branches is given along with all of the branches. When all branches are done executing the node checks how many were successful and if the number of successful branches is greater than or equal to the minimum number of required successful branches the *MParallel* is deemed successful. **SParallel** The last implementation of the parallel node is the *SParallel* class. This class implements a version of the parallel, where several branches are given along with a list of which branches must succeed, in order for the *SParallel* to succeed. There may be branches that are not necessary for the successful run of the parallel and these may fail or succeed but have no influence on the result of the parallel node. Only the branches defined in the list of branches that must succeed have an influence on the result of the *SParallel*. **Selector** Selector nodes are used for selecting a branch of a BT based on some defined way of selecting. In our framework we implement two types of selector nodes and these are described below. **SequentialSelector** The *SequentialSelector* class is the simplest of the selector nodes. It simply tries executing its children one by one until one of them succeeds. If no children succeed the selector fails. 4.1 Framework ProbabilitySelector The ProbabilitySelector class implements a selector that selects amongst its children based on a probability for each child. As it is given by the definition of a selector node the ProbabilitySelector node must select a child based on the probability for each of the children until one of them succeeds. 4.1.3 Execution of a Behavior Tree The nodes and features of the BT framework have been described but the structure of the framework is not enough to successfully construct a BT. It is also required that the programmer and game designer know how a BT is executed. In this section we will describe how the execution of a BT is done. We will use the BTs shown in Figure 4.8 as an example for the description. ![Figure 4.8: BTs for examplifying execution](image) In Figure 4.8 we see two trees. The first, T1, is the main tree of the example and ST1 is a subtree that we will use to show how link nodes work. As the trees are used to examplify execution we will not define what specific actions and conditions do but rather concentrate on the flow of execution. We also define the results of the leaf nodes, conditions and actions, in Table 4.1. <table> <thead> <tr> <th>Node Name</th> <th>Result</th> <th>Execution Time</th> </tr> </thead> <tbody> <tr> <td>C1</td> <td>Success</td> <td>1 ms</td> </tr> <tr> <td>A1</td> <td>Failure</td> <td>5 s</td> </tr> <tr> <td>A2</td> <td>Success</td> <td>2 s</td> </tr> <tr> <td>A3</td> <td>Failure</td> <td>1 s</td> </tr> <tr> <td>A4</td> <td>Failure</td> <td>50 ms</td> </tr> <tr> <td>A5</td> <td>Success</td> <td>5 s</td> </tr> </tbody> </table> Table 4.1: Execution result for leaf nodes We recommend that the programmer uses the BT thread wrapper for executing BTs. This is due to the handling of the barriers needed, if an action takes time to execute and the executing thread cannot hold until the action is done. For example pausing execution, so the game frame can terminate, avoiding lag in the game experience. Specifically, in StarCraft there is on average 40 ms of execution time per game frame. Even though the actions do not take time to finish execution it is recommended to use the wrapper if the tree contains parallel nodes. This ensures that the parallel returns correctly as all threads are synchronized around the barrier from the wrapper. This is also why our example will use the thread wrapper class. When the BT is instantiated with the nodes it contains, it is added to a `BehaviorTreeThreadWrapper`, which sets a barrier throughout the BT and subtrees. Once this is done the thread wrapper is ready to execute the BT. The execution is initiated with the `Start` method. This method starts the thread executing the BT. The execution of a BT starts by calling the `Execute` method of the root node of the tree. All nodes are required to implement the `Execute` method to ease execution. The root node in the example in Figure 4.8 is PS1, which is a probability selector node. The probabilities define how likely the node is to execute each of its children. PS1 will execute the first branch with probability 0.9 and the second branch with probability 0.1. The `Execute` method of the probability selector will select a branch based on these probabilities and here we assume it selects the first branch, due to the high probability. The probability selector then executes the `Execute` method of the child in the first branch. This child is the sequence node Seq1. Seq1 will start executing its children one by one until either one fails or all children succeed. Seq1 starts by calling `Execute` on the condition node C1. From the Table 4.1 we see that C1 is defined as succeeding with an execution time of one ms. For this reason we will not need to pause the execution as one ms execution will not cause lag in the game. This means that the first child of Seq1 has succeeded. Seq1 will then execute the next child which is the action node A1. The action node A1 can take time to execute and in Table 4.1 we define it as taking five seconds to execute. For this reason we need to allow the tree to pause execution while the action is performed in the game environment. To better illustrate why this is important, imagine that the action is a move command to a unit. It will take some amount of time for the unit to move to the given position and the action node cannot return success or failure before it has either reached the position or it has failed to do so. Here the barrier from the thread wrapper comes into play. As we are still running as part of the `Start` method of the wrapper, we halt the execution of the tree by signaling and waiting at the barrier. The thread wrapper is waiting for this condition to be true. Once this happens the Start method will return and the game can continue execution. To resume execution of the tree, the Continue method must be called e.g. on the event of a new game frame. This method releases all those threads waiting at the barrier and waits for them to either terminate or reach the barrier again. A1 may take several game frames to terminate and as such the thread may be awoken many times before it can determine if the action has terminated. A1 is defined to be a failure and will return this to Seq1. Seq1 will then, because one of its children failed, return a failure to PS1. A selector node handles failure by executing another of its children. PS1 will try to execute SS1 which is the other child of the selector. SS1 is a sequential selector that will attempt to execute its children one by one until one succeeds or all children fail. SS1 will first execute the link node pointing to ST1. A link node simply executes another BT and the success or failure of this tree defines the success or failure of the link node. ST1 is a small subtree and is depicted in Figure 4.8b. The root node of the tree is the parallel node AP1. AP1 requires all of its child threads to succeed in order to succeed itself. AP1 starts two new threads, one for each of A2 and A3. AP1 then removes a participant from the barrier and adds two new for the children. The reason that a parallel node removes a participant from the barrier is because the parallel node will start busy waiting on the child threads to complete. This must be done separately from the barrier, as it would not reach the required participants to pause execution of the tree otherwise. Each child, A2 and A3, will now execute their actions. These actions take some time to execute as well and this will cause the actions to pause execution until they are done. In Table 4.1 we see that A2 succeeds and A3 fails. As AP1 required all children to succeed the node fails resulting in a failure of ST1. SS1 will attempt to execute its second child as ST1 failed. SS1 then executes D1. D1 is a decorator. Decorators are as explained the wild cards of BTs. These nodes can add features not available through the use of other nodes. In our example we imagine that D1 runs an algorithm to select a position on the game map needed in the rest of the branch. D1 then proceeds to execute its child MP1. MP1 is a MParallel node. MParallel nodes are given a specific number of children that need to succeed in order for the node to succeed. MP1 has two children and it requires one of them to succeed. A4 and A5 will then be executed just as with A2 and A3 under AP1. Table 4.1 shows that A4 will fail rather quickly. This has no immediate effect on the node as the rest of the nodes need to terminate before the result can be determined. Once A5 terminates with success MP1 will determine that it has succeeded. The success of MP1 will in turn affect D1 which also succeeds. SS1 will now also succeed as one of its children succeeded. SS1 is a child of PS1 which also relies on one of its children to succeed in order to succeed. This condition is now also true as SS1 succeeded. PS1 is the root node of T1 and as PS1 has now succeeded, the tree T1 has executed with success as a result. 4.2 Editor The purpose of the editor is to supply the framework with the structure of the BTs, such that they are ready to be executed by the framework. For this, the editor is developed as a visual designer where BT nodes can be arranged and connected into BTs visually, giving an easily comprehensible structure of the BTs compared to the actual code representation in the framework. The editor is implemented in WPF using an article series on developing a Diagram Designer by the user sukram available at The Code Project [22]. GUI Layout The current revision of the editor offers a simple interface with a set of basic features needed to build BTs. Figure 4.9 shows the layout of the editor. ![Figure 4.9: Main window layout in the editor.](image) The interface can be separated in two distinct areas: A menu area and a designer area. The menu area contains buttons for each available BT node that can be added to the designer area and used to construct BTs. Implementation of the nodes and how they are presented in the designer area is discussed in Section 4.2. The File menu entry offers export to PNG image files of the BT in the designer area. Furthermore, the File menu entry holds an Exit option, which closes the editor. Designer Canvas The designer area handles visual representation of the BT nodes and allows creation of BTs and editing these. It is implemented with the DesignerCanvas class which inherits the Canvas class available in .NET. The canvas class defines an area where child elements can be explicitly positioned using coordinates within the canvas frame. Selecting one of the available BT nodes in the menu area, adds the given node to the child collection of the canvas, thus making it visible in the canvas frame. The DesignerCanvas class overrides the Canvas class’ *OnMouseDown*, *OnMouseMove* and *MeasureOverride* methods. Overriding the OnMouseDown and OnMouseMove methods, multiple nodes in the canvas can be selected for editing by holding down a mouse button and drag-selecting a set of nodes. This makes it easy to select a subtree of the current BT and e.g. reposition the entire branch. The MeasureOverride override handles resizing of the canvas when nodes are moved outside the bottom or right bounds of the canvas. The canvas is then properly resized according to the repositioning of the nodes. **Node User Controls** The individual BT nodes that are added to the canvas are implemented as simple *User Controls*. User controls can be viewed as reusable components that can contain other controls, resources and more. There are almost no limitations to what can be contained in a user control, making them ideal for creating the BT nodes. The implementation of the sequence node user control in the XAML visual editor can be seen in Figure 4.10 while Listing 4.1 is the corresponding XAML code. ``` < UserControl x:Class="BehaviorCraft.Resources.Nodes.SelectorShape" mc:Ignorable="d" d:DesignHeight="40" d:DesignWidth="200"> <Border BorderBrush="Black" BorderThickness="3, 3, 3, 3" CornerRadius="8, 8, 8" Background="White"> <Grid> <Label Content="Label" Height="28" HorizontalAlignment="Center" Margin="12, 0, 12, 0" Name="SelectorLabel" VerticalAlignment="Center" VerticalContentAlignment="Center" FontWeight="Bold" FontSize="16" Padding="1"/> </Grid> </Border> </UserControl> ``` *Listing 4.1: The XAML code for a selector node.* All the BT node user controls share the `<Label>` control, with the *Name* property differing. This label handles the name displayed on the corresponding node, and is supplied by user input whenever a node is added to the canvas. Sizing of all the node user controls when added to the canvas is handled automatically with respect to the text length of the label. When nodes are added to the canvas, they are not added directly by their user control representation. Instead the class *NodeItem* is used as a container class for all nodes being added to the canvas. This class inherits the *ContentControl* class from .NET, which allows us to add the node user controls as the NodeItems content using ControlControls *Content* property. 4.2 Editor The NodeItem class also uses the MoveThumb and Connector classes as templates. The Connector class handles the connection points on nodes used to visually link parent and child nodes on the canvas. This is described in greater detail in Section 4.2. MoveThumb inherits the Thumb class from .NET, which has a DragDelta event. The DragDelta event is fired when a NodeItem is clicked and dragged. An MoveThumb_DragDelta event handler is added to DragDelta, which handles repositioning of NodeItems within the canvas as a response to the DragDelta event. This allows a user to freely reposition individual or multiple nodes within the canvas frame by simply dragging them around. Connecting Nodes Visually connecting parent and child nodes in the canvas is implemented using four classes, and is best described step by step. Figure 4.11 shows in four steps how a parent node is connected to a child node. ![Figure 4.11: Creating a connection between a parent and a child node.](image) When hovering the mouse over a node in the canvas, two connector points on the node becomes visible as can be seen in Figure 4.11a. The connector points are added to the NodeItem as a template using the Connector class as the template. The Connector class handles the connector point relative to the node’s position in the canvas. All nodes currently share the same Connector template, which is why both non-leaf and leaf nodes have two connector points. By clicking the mouse and holding the mouse button a connection can be made to a child node by dragging a connection to it. Figure 4.11b shows how the drag connection is visually represented by a line between the parent node and the current position of the mouse. This line is handled by the ConnectorAdorner class using an Adorner from .NET. An Adorner works like an elastic rubberband in the sense that it can expand and contract according to e.g. the mouse being moved. As the drag connection nears a connector point on the child node, the child nodes connector points becomes visible as shown in Figure 4.11c. Letting go of the mouse button with the drag connection on a connector point creates a connection between the parent and the child node. The connection is handled by the Connection class, which mainly handles the visual representation of a connection as seen in Figure 4.11d. Finally, whenever a parent node, child node, or both are repositioned in the canvas frame as a result of a drag movement, the connection between these also need to be repositioned. This is handled by the ConnectionAdorner class, which inherits the Adorner class. An adorner is used as described for the drag connection previously. 4.2 Editor Building a Behavior Tree The editor currently supports all BT nodes specified in Section 3.3 and thus it is possible to build BTs utilizing all of these nodes. Figure 4.12 shows the strategy BT from Section 5.1 built in the editor, using selector, sequence, condition and link nodes. The editor is available for testing on the CD enclosed with the report. ![Behavior Tree Diagram] Figure 4.12: The strategy BT constructed in the editor. In the previous chapters we introduced the game Starcraft which we will use for our case study. Furthermore, we looked at the theory of BTs and introduced our proposed framework. In this chapter we will construct the BTs that we are going to use for testing. These trees are based on the simplified scenario we introduced in Section 2.4. The way we decided to construct the BTs is by separating the what from the how. We have the main BT, **Strategy**, that consists of the strategies we can apply, which is the what. Each strategy is a link node that links to another BT. These trees define how the strategies are going to be executed, the how. Another way to construct the BTs, is to assume we have a goal we want to achieve. To achieve the goal we need some subgoals, and to achieve these subgoals we need sub-subgoals etc. As an example of this take a glance at Figure 5.1. Our main goal is to run a strategy. However, to run a strategy we need to choose one and to choose one we need some strategies we can choose from. We continue to do this until the whole tree is constructed. The following subsections describe our BTs in more detail. ### 5.1 Behavior Tree: Strategy The **Strategy** BT is the top most or main tree of all the BTs. It is the tree that decides which strategy will be used in a game. The tree is illustrated in Figure 5.1. The sequence **Run strategy** first checks the condition !(Game over?) to check whether the game is finished or not. If it returns success it will run the selector **Choose strategy** that will choose to run one of its children. All these children are link nodes, which will execute other BTs. It can either be **Attack and scout**, **Harass**, **All in**, **Defend** or **Multiple attacks**. 5.2 Behavior Tree: Attack and Scout The Attack and scout BT depicted in Figure 5.2 shows how the Attack and Scout BTs are executed simultaneously. First, the Attack behavior allocates 12 marines. It then chooses one attack route among the three possible choices Top, Mid and Bottom, and issues the attack order to the units. The Scout behavior orders one unit to each lane, to scout for information about the opponent. Both BTs can be seen in Figure 5.3. Figure 5.1: Strategy BT. Figure 5.2: Attack and scout BT. 5.2 Behavior Tree: Attack and Scout As scouting is vital in our scenario of StarCraft, we need the scouting marines to stay alive as long as possible. Which brings us to the Scout move top BT that is given in Figure 5.4. Even though the Scout BT links to three different BTs. We choose only to describe one of them, as they are all very similar to each other. The only difference between them is the scouting route for the marine. ![Figure 5.3: The BTs of Attack and Scout](image-url) This tree handles the scouting behavior of a marine. What we want to achieve with these scouting marines, is to get information on the enemy without getting the scouting marine killed. So if the enemy tries to kill the scout, we move away. When the marine is safe, we move in again to get vision of the enemy. As we see in the tree, there are two branches. The left branch handles the route from our HQ to the top left corner of the map, which we call top. The right branch handles the route from top to the enemy’s HQ. The marine will move to top if he encounters no enemy units. However, if he gets vision of enemy units on the route to top, he will move back to the HQ. The same applies for the right branch. The marine will move to the enemy’s HQ as long as he encounters no enemy units. If he does encounter enemy units, he will immediately move back to the top. ### 5.3 Behavior Tree: Harass The *Harass* BT in Figure 5.5 handles the strategy for harassing the opponent. We allocate six idle marines and order them to harass the opponent through one of the three attack routes Top, Mid or Bottom. Each of these branches in the tree will execute the *Harass move* BT for their respected lane. The *Harass move mid* tree, illustrated in Figure 5.6, handles the subtle details for the harass strategy in Mid path. ![Harass BT](image) **Figure 5.5:** Harass BT. The tree handles it by having a strategy we call *Hit and run*. We want the 6 marines allocated earlier to go down the mid attack route and harass the opponent without too many casualties. First we check whether the enemy is visible or not, if he is not visible we move our marines towards the opponent’s HQ. We then check again for visible enemies, if we are able to see the enemy, we check whether our marines are in range of the enemy. If not, we move in range and proceed to attack the nearest enemy units for one second. Afterwards we retreat from the enemy. 5.3 Behavior Tree: Harass Figure 5.6: Harass attack BT. 5.4 Behavior Tree: All In The *All in* BT in Figure 5.7 gathers all the units we have and sends them to attack the opponent through the mid lane. This strategy is risky as it leaves the HQ vulnerable to flank attacks from top and bottom. In this example we define that the BT must have 13 marines available. This is a dummy condition to show that it is necessary to have a condition here, otherwise the BT would all in with as little as one marine. ![Behavior Tree Diagram] *Figure 5.7: All in BT.* 5.5 Behavior Tree: Defend The *Defend* strategy handles the defence of the HQ. The *Defend* tree in Figure 5.8 has two phases of defence. In the first phase, we try to defend by using only nearby units. As a result, units that are already attacking the enemy will keep attacking the enemy, while units nearby our HQ will be gathered in front of our HQ to defend it. The second phase of our defend strategy activates when the first one fails, meaning all the defending marines died. In the second phase we send all units we have on the map back to our HQ to make a last stand. ![Defend BT Diagram](image) *Figure 5.8: Defend BT.* 5.6 Behavior Tree: Multiple attacks The last strategy is the Multiple attacks BT, which is illustrated in Figure [5.9]. We take our main force and split it into either two or three groups. If we split into two, there are three possible lane options to choose from. We can either attack from top and mid, from top and bottom or from mid and bottom. If we split the army into three, we will attack at all three fronts simultaneously. As we see in Figure 5.9, no matter what branch we choose to run, when we split the army in two, we will end up in a link node. The trees that are linked to are quite simple. The root node is followed by a parallel node, followed by the specific attack route node, ending with the action nodes that issues the attack order. An example of one of these BTs is given in Figure 5.10. ![Diagram of Multiple attacks BT](image-url) *Figure 5.9: Multiple attacks BT.* 5.6 Behavior Tree: Multiple attacks Figure 5.10: Multiple attacks through mid and bottom BT. We have based the tests the BTs proposed in Chapter 5 and use these to show whether it is possible to apply BTs in creating AI for StarCraft and, through this, if BTs can have a general application in RTS games. We will test each strategy behavior by itself. Based on the performance of the behavior, we will discuss what we expected to happen, what did happen and how to correct possible mistakes in the behaviors. The results of these tests are based purely on our subjective opinion of performance and flaws in the behavior compared to the theory of BTs described in Section 3.3. Replays from the All In, Harass Attack and Defend tests are available on the attached CD or by request from the authors. ### 6.1 Test: Attack and Scout The behavior we want to test here is shown in Section 5.2. The behavior is designed to be a basic strategy where the AI will attempt to attack in one of the three paths while scouting all paths with one marine. **Expected Behavior:** We expect to see two things from this behavior. First off we expect to see the behavior send out three marines; one to scout each path. Second we expect it to assemble 12 marines and attack along one of the paths with an approximate probability of $\frac{1}{3}$ for each path. **Observed Behavior:** We observed some flaws in the scout behavior, mainly due to race conditions on the list of available marines. This is caused by the simultaneous allocation of one marine to each path. Also, when running the attack tree alone, the behavior is capable of attacking along one of the defined paths. When running one of the branches of the scout tree alone, the allocated marine was able to scout the path and run away when encountering enemy units. **Evaluation:** It was possible for the behavior to execute its components individually, but the simultaneous execution proved problematic. We will have to address the problem of simultaneous execution to improve the functionality of the framework. 6.2 Test: All In The behavior we want to test here is shown in Section [5.4]. In this behavior the AI will assemble all available forces and attack through the mid path with full force. The aim is a last resort move when nothing else is possible. Expected Behavior: We expect to see that the behavior will gather all available units, which in this case will be 13 marines, and attack through the mid path of the map. Observed Behavior: The human opponent attempted to harass the AI, but the behavior executed the all in strategy, when it had gathered 13 marines. The AI attempted to attack through the mid section of the map as intended and eliminated scouts along the path. However, the behavior crashed, when the main battle at the enemy HQ was underway. This was due to a loop inside the attack action node, which iterates through the allocated marines to check whether they are dead. This collection of marines must not be modified during iteration, which was what happened. Again we are seeing problems with the simultaneous execution of the BTs. Evaluation: The behavior acted as intended by design, but the crash failure is a definite concern. We will need to investigate solutions for the dynamic handling of marine deaths. 6.3 Test: Harass Attack The behavior we want to test here is shown in Section [5.3]. The harass behavior is the most complex behavior in the test and as such we have only implemented one subbranch of the tree. In this behavior we want to use six marines and attempt to take out enemy marines without losing any marines. Expected behavior: We expect to see the behavior gather six marines and run along the mid path. From then on it will attempt to find one common target, the closest to the group, and attack this target for one second before running away. Observed behavior: We saw the behavior assembling six marines and attempt to take out one marine at a time. The behavior did the intended hit and run style attack taking out, or damaging, one marine. There were some issues in the implementation, which seem to be caused by the structure of the harass BT. 6.4 Test: Defend Evaluation: This test showed, how hard it can be to create a behavior that mimics a common playstyle of a human player. The complexity made the tree prone to structural errors. The nodes and the framework itself did not show any errors during this test. The behavior we want to test here is shown in Section 5.5. The behavior will, given the HQ is under attack, attempt to move nearby marines back to defend it. If unsuccessful, all units on the map will be moved back. Expected Behavior: We expect to see the behavior order all the units closest to the HQ back, in an attempt to defend it, if it is under attack. If all nearby friendly units are killed, we expect to see the behavior order all units back to the HQ in an attempt to defend it. Observed Behavior: The behavior acted as intended. When enemy units started attacking the HQ, all nearby units were ordered to attack move towards the friendly HQ, to take out the enemy units. The enemy units were eliminated, however the check to avoid phase two failed to stop the sequence, making the marines attack move towards the mid of the map. Evaluation: The behavior did as intended, but structural errors and lack of proper methods in BWAPI to check whether a structure is under attack, made it problematic to implement the intended behavior. 6.5 Test: Multiple Attack The behavior we want to test here is shown in Section 5.6. This behavior is similar to the attack behavior. The difference lies in the behavior’s attempt to attack the enemy on several fronts simultaneously. Expected Behavior: The multiple attack behavior has two distinct execution branches. One branch attempts to attack two paths at once and selects one of the three possible pairs of paths. The other execution branch will attempt to assemble enough marines to perform an attack in all three paths simultaneously. We have defined, that no matter which execution path is followed, there must be at least 12 marines allocated to each path, giving 24 marines in a two front attack and 36 in a three front attack. 6.5 Test: Multiple Attack **Observed Behavior:** Observations show that the behavior is able to allocate both two and three groups of 12 marines for use in attacks. We could also observe that the behavior was able to choose a pair of paths for the two front attack. However, due to the way the scenario is constructed and the execution speed of the tree, the three front attack was only chosen when we disabled the two front attack option. **Evaluation:** The test showed that the behavior acted the way it was intended, but as mentioned there were problems choosing between the two types of multiple attack. The reason for the three front attack was not executed, was because it never accumulated the required 36 marines. Due to this, the condition checking whether the marines were available would fail, causing the sequential selector that chooses between the two types of multiple attack, to choose the two front attack, because it is easier to accumulate 24 marines. This problem is in itself not caused by BTs in general, but rather a problem that must be addressed during the design of the behavior. A solution, could be to introduce a latch that would continue to attempt the selected multiple attack several times, before failing and trying the other one. Improving Framework and Editor Based on the experience received from the previous chapter on testing, we will in this section discuss future improvements for both the framework and the editor. 7.1 Framework Improvements During the development and later use of our framework several key areas have been identified for improvement. Interrupts/Exceptions A key improvement on the current framework would be to implement interrupts and/or exceptions. These should be implemented to make it possible to reset the tree or parts of the tree when certain, perhaps unexpected, events occur. An example of its use is if a marine is being moved as part of an action node execution, the marine might encounter enemies while moving. Here an interrupt could be thrown to allow for a switch in the execution to order the marine to retreat. As we would like to avoid game API specific code to be in the framework, a solution to implement interrupts, could be to only allow action, condition and decorator nodes to throw interrupts and only allow decorators to handle them. By doing it this way, we can implement a standard way of passing interrupts up the tree, by making the basic constructs, such as sequences and selectors simply pass the interrupt to their parents, until it reaches a decorator that is capable of handling the interrupt. If the interrupt reaches the top of the tree, two things could happen; one could be that the tree throws an unhandled interrupt error informing the game designer that something is wrong, or that the tree simply resets itself and restarts execution. Blackboard After using the blackboard in its current state, where each BT has its own blackboard, we have come to realize this is not an optimal solution. Since this imposes a lot of extra work during coding to make sure which blackboard each value is written. The process of making the blackboard simple will not have an impact on the overall functionality of the BT framework. We would also like to make the blackboard type safe by ensuring that the requested value has the expected type when executing the blackboard, rather than checking the value, when it has been returned. BehaviorTreeThreadWrapper After using the framework for testing, we have come to the conclusion that the BT thread wrapper can be merged into the BT class itself. There is no need for a separate class. One of the things that we have concluded is that it is always necessary to have a barrier and as such this should be defined in the tree class itself. If the barrier is in the tree class, the execution, pausing and resuming of the tree can then also be merged into the class. This makes it possible to use both threaded and unthreaded BT execution from the same class. **More basic constructs** The framework could benefit from more basic constructs, such as builtin loop decorators that either iterate a number of runs, or a number of successes/failures. Another basic construct that could be useful is a wait decorator capable of waiting a given amount of time, before executing its child. **Debugging directly in the IDE** As a way of making it easier to debug constructed BTs, we would like to add the ability to debug the projects directly in an IDE, such as Microsoft Visual Studio. One solution to this could be, with permission from the author, to include the bwapi-mono-bridge projects directly in a solution, so that compiling and debugging can happen in Microsoft Visual Studio. ## 7.2 Editor Improvements The current implementation of the editor does not have functionality to work together with the framework, as a few features are still missing. **Exporting Behavior Trees** It is not possible to export the BTs created in the editor to the framework, which is a key feature for the editor to be of actual use. Exporting the BTs to e.g. XML format would allow us to load it into the framework, by parsing the XML code and then constructing the BTs automatically. Currently BTs have to be coded manually in the framework, which takes considerably longer time, compared to building them in the editor and exporting them to the framework. **Node Properties** Other than the difference in the visual appearance of nodes, there are no distinct properties for the individual nodes in the editor. It is not possible to set the probability distribution for a probability selector, edit the contents of a decorator node, defining which BT a link node links to e.g. To accommodate this, a property editor, that becomes visible when individual nodes are selected, should be implemented. **Multiple Canvases** The editor only allows for one BT to be built, because there is only one canvas with one root node. Being able to have multiple canvases open at once will remove this limitation. This can be implemented either as different canvas tabs, like webpage tabs in web browsers, or having multiple windows opened, each 7.2 Editor Improvements with a canvas. Working on multiple canvases at once, would also allow use of the link nodes to link to a BT on another canvas. Conclusion To summarize the work done in this project. We have: - Discussed the game of StarCraft to address some of the challenges, creating an entertaining and challenging AI for RTS games. - Presented a survey of scripting, FSM and BTs on their applicability in RTS games. - Implemented a framework and editor for using BTs in behavior creation. - Successfully applied BTs, creating an AI for an RTS game scenario. First of all by addressing the different aspects of StarCraft, we highlighted the challenges, creating an AI for an RTS game. The overall micro management and macro management aspects of StarCraft, also exist in most other RTS games. The scenario created for the case studies served well as a simplification of a full game scenario, as it captured the important aspects of the game. The elements of resources and base building were left out of the scenario to simplify it further, such that we could focus on strategic decision making and disregard build orders and resource management. As the evaluation of the different AI methods pointed out, scripting and FSM had their strength and weaknesses. BTs attempt to address these weaknesses, by being more structured and modular. The modularity and reusability of BTs showed its usefulness, when all the framework nodes and nodes interacting with the game environment were implemented. With all the building blocks ready, it was just a matter of building behaviors, according to the trees designed in Chapter 5. Through tests of the proposed BTs we saw an indication that BTs can be used for creating AIs for RTS games. There are of course problems that are unique with regards to the BT and RTS game combination. Amongst these, the most apparent seems to be the handling of the fact that units may or may not exist during execution of the behavior, as opposed to a behavior driven NPC player in an FPS game. After doing the tests, we discovered several key points for improving the BT framework. The most important problems discovered, concerns the threading execution of the trees. It introduces several possibilities for race conditions and deadlocks. These problems are of a general concern, when using threading, but it is necessary to look at solutions, to minimize the risk of encountering them. Additionally, the editor still needs further improvement for it to be functional in combination with the framework. It is currently not possible to export BTs from the editor and use them in the framework. 8.1 Further Work The work done in this report introduces several possibilities for further study in the area of BTs. BTs have been shown to be a possibly viable method to handle the AI in an RTS game, namely StarCraft. However, as with the commonly used methods for AI in the game industry, scripting and FSMs, BTs only exhibit static behavior. The framework and editor implemented and documented in this report serve as a great foundation for developing and utilizing BTs in StarCraft. As pointed out in Chapter 7 there is still room for much improvement of both the framework and editor. Based on the work done, we propose two general suggestions for further study and research. 1. How can the framework and the editor be combined and improved to fully utilize the notion of BTs in game AI and assist in making the creation of BTs less complex? 2. Can the notion of BTs be extended with classical AI techniques to create more adaptive and human-like behavior. As we described in Chapter 3, the goal of game AI development is to provide entertaining and challenging AI opponents, that display intelligence and human-like behavior. In other words, the ideal goal of game AI research is to create AI which is indistinguishable from a human. Such AI would give players the best possible experience when playing. As Alan Turing once pointed out: "If a machine acts as intelligently as a human being, then it is as intelligent as a human being." We are still a long way from achieving this goal, but as new methods and theories emerge, we come ever so close to reaching this goal. Figure A.1: Class diagram for the Poker test environment Figure B.1: Sequence diagram showing the execution of a behavior tree Bibliography
1. Description 1.1 Name(s) of society, language, and language family: Rukuba - Language: Rukuba, Che (a language of Nigeria)¹ - Alternate names: Bache, Inchazi, Kuche, Sale² - Language Family: Niger-Congo, Subfamily Benue-Congo, Group Pleateau A, Subgroup 4 – none of their immediate neighbors understand this language⁴ - Language is “Kuche”, a speaker is “Ache”, the people are “Bache”¹ 1.2 ISO code (3 letter code from ethnologue.com): ISO 639-3: ruk¹ 1.3 Location (latitude/longitude): Plateau state, Bassa LGA¹ “Central Nigeria, on the High Plateau at some 30 kilometers west of the town of Jos, capital of Plateau State”⁴ “The Rukuba say that they come from Ugba, a site lying some forty miles northeast of where they presently are. They claim to have been there together with the Jere, the Amo, the Buji, and, according to some accounts, the Chara, all populations neighboring the Rukuba, with whom they still have numerous links, in spite of speaking different languages. However, the Rukuba belong to the Plateau 4 linguistic subgroup of Greenberg’s classification, the Amo, Buji, and Jere speaking different dialects of a common language called Jera by Hansford. From a close examination of the linguistic map of the High Plateau, Ballard has made the hypothesis, with much plausibility and in spite of what the Rukuba say, that the Rukuba had been pushed northward by the intruding Birom, their cognate ethnic groups being similarly displaced but in the southwestern direction” (3p64). 1.4 Brief history: “The Rukuba claim to have migrated to their present territory from Ugba, a locality about 64 kilometers northward. Their historical tradition connects them closely with neighboring peoples of different linguistic subgroups, the Jere, the Buji, the Ribina, the Amo and, some say, the Chara. This migration is difficult to date, but the eighteenth century seems the best estimate, although it might have taken place earlier. Linguistically isolated, the Rukuba nevertheless have various formal links of a ritual nature with thirteen neighboring populations that are also small by African standards. In spite of the language barrier, these peoples formally invite representatives of other groups to communal hunting, to initiation ceremonies, to certain funerals, and so on. The British, while searching for tin on the High Plateau, subdued the Rukuba in 1905. Tin extraction by soil washing began in mining camps, providing an opportunity for the local peoples to pay a newly introduced personal tax without migrating away for long periods. This explains the relative conservatism of these Plateau ethnic groups, which met the monetary needs of the British administration by getting hired in mining camps for only a few weeks a year or by growing foodstuffs for the foreign permanent residents in the same mining camps. The town of Jos also offers some opportunities to work without going far away from home.”⁴ 1.5 Influence of missionaries/schools/governments/powerful neighbors: “Though their recent political activities are evidence of their ability to adapt themselves to modern conditions, culturally the Rukuba have changed relatively little since the British administration of the Plateau. As late as 1950, only two of the seven Village-Group Heads spoke Hausa, and though Christianity has made slight headway—through a mission at Kakkek—Islam is said to have made no mark. The Rukuba have little to do with the mines in their area, apart from selling food to immigrant workers: they seem to depend chiefly on this trade and on the Jos and Bukuru markets for their tax-money, rather than on working in the mines themselves” (2p36). “More is known on the social structure of the Rukuba than of other members of the Jerawa Group, though its different aspects cannot be linked together with any great certainty owing to the lack of detailed evidence” (2p37). 1.6 Ecology (natural environment): “The Rukuba inhabit a rugged country and, until the mid-1950s, when some of them descended to the foothills, lived on the hilltops, where many still remain. The geography is Northern Guinea zone characterized by thickets on the hills and ‘orchard bush’ (cultivated land on which useful trees have been retained). Elevation is about 1,200 meters; annual rainfall averages 150 centimeters and falls mainly from April to September, with a peak in July-August. The average temperature in the early dry season (December-January), when the northern wind blows, is 20.5° C; it rises to 25° C in March-April, the hottest months, and goes down again in the wet season.”⁴ 1.7 Population size, mean village size, home range size, density: 100,000¹, Currently 12,000³ “Occupy a territory of about 440 square kilometers with a population density of nearly 27 people per square kilometer”⁴ 2. Economy 2.1 Main carbohydrate staple(s): “The staple crops of the Rukuba are fonio (Digitaria exilis and D. iberua), sorghum, and late millet, the proportion varying from village to village, according to the quality of soils. Eleusine millet and sesame are also grown in far lesser quantities.” 2.2 Main protein-lipid sources: No evidence found 2.3 Weapons: Bow and arrow, blowguns?: No evidence found 2.4 Food storage: No evidence found 2.5 Sexual division of production: “Men and women both perform agricultural work, but the men do the heaviest part of the hoeing. Both sexes cultivate the same plants, but women specialize in groundnuts, Bambara nuts, sweet potatoes, sesame, eleusine millet, and most pulses. Men cut firewood, but women carry it home. All meals, except ritual ones, are prepared by women. Men do all husbandry and hunting. Women fish with small nets; men trap fish. Women do all basketry; men plait sleeping mats and beer filters and craft all leatherwork, such as baby carriers and sheaths for swords and knives. Mortars, pestles, wooden seats, and wooden spoons are carved by part-time specialists, of which there are only few. Blacksmithing, in spite of its high prestige, was—and still is—a part-time occupation. Soothsayers and local medicine men also practice agriculture.” 2.6 Land tenure: “Land passes from father to son(s), women being excluded from land inheritance because they work on farms allotted to them by their husbands. Patrilineal people tend to remain together at the same location generation after generation; if a man has too many sons, land will be sought from remote patrilateral kin whose family is depleted. Land can also be borrowed on a short- or long-term basis—or even bought, from neighbors who have enough farms.” 2.7 Ceramics: No evidence found, but as iron smelting was common before the British arrived—and blacksmithing after—it can be assumed that this artistic group of people had some ceramic creations. 2.8 Specified (prescribed or proscribed) sharing patterns: No evidence found 2.9 Food taboos: “According to Counsell totemic ideas and taboos are not well-marked. ‘The harmless dako snake is regarded throughout the tribe as a special friend and never killed; it is encouraged to live in their huts, where it performs the duties of the domestic cat…Leopard flesh may not be eaten except by a few (e.g. the people of Binango in Kakkek)….The skin is usually the perquisite of the Utu, who does not, however, wear one. The ant-eater must not be eaten except by old men…, and women who see one must be ceremonially cleansed…Women must not eat hens or eggs…” (2p41). 2.10 Canoes/watercraft?: No evidence found 3. Anthropometry 3.1 Mean adult height (m and f): No evidence found 3.2 Mean adult weight (m and f): No evidence found 4. Life History, mating, marriage 4.1 Age at menarche (f): About twenty years old 4.2 Age at first birth (m and f): No evidence found 4.3 Completed family size (m and f): As women can marry as many men as they want, there appears to be no specific number of family members one can have. 4.4 Inter-birth-interval (f): No evidence found 4.5 Age first marriage (m and f): “It is stressed that primary marriage does not usually take place before a girl reaches the age of twenty. Meanwhile, after puberty, when she is given her own sleeping-hut, she entertains lovers, who may themselves be married or single” (2p40). 4.6 Proportion of marriages ending in divorce: “Wife stealing is common and most wives leave their first husband” (2p40). However, there doesn’t seem to be any evidence of an actual divorce. Most wives will take a “co-husband” – or several – instead. 4.7 Percent marriages polygynous, percent males married polygynously: “Probably of great importance, as it might adjust to some extent the apparent lack of balance between the two exogamous units, is the practice of zaga (so named from the Hausa word meaning ‘to skulk about a place’), interest in which later led Meek to discover the institution best known as secondary marriage. Meek describes a highly generalized form of this institution: a man abducts the wife of another, with her and her father’s consent; it is conventional for the woman to reassure her first (primary) husband of her goodwill, and the man makes customary gifts to her parents, establishing the man as ‘co-husband’: Ames states that Rukuba marriage-payments and farm-service are commonly regarded as inconsiderable, and adds that a husband ‘deserted’ cannot recover payments made, stressing that ‘wife-stealing is common and most wives leave their first husband.’ The children of these unions are said to belong to the group of the biological father, but the means of determining the father are not indicated. According to Meek, the same system prevails among members of the Katab group; M. G. Smith, working among the Kagoro of Zaria Province, found that a wife may regard herself as simultaneously married to two or more husbands, to any one of whom she may pay formal visits for periods of six months or a year in respect of each. She continues to call all these ‘husband.’ She is inherited on his death by one of the husband’s kin. There is, of course, no indication how far the Katab system applies among the Rukuba. Of the intricacies that have been found to exist at Kagoro there is so far scant indication among the Rukuba” (2p39-40). 4.8 Bride purchase (price), bride service, dowry?: “Counsell states that a woman may resist the advances of a secondary suitor, and adds that the payment made to a secondary wife’s parents amounts to about half that made in the case of a first marriage. He confirms that the primary husband receives no compensation, provided his wife has remained with him for at least one year; but ‘the first husband can always hope to persuade her to return to him, and if she does he would have to make no further payments to her parents’” (2p40). 4.9 Inheritance patterns: “Inheritance passes from father to sons and is divided equally. If there are no sons, the next agnate in line—brother or paternal cousin—will inherit the most important property: land, goats, hoes, and debts, if any.” 4.10 Parent-offspring interactions and conflict: No evidence found 4.11 Homosexual activities, social attitudes towards homosexuals: No evidence found 4.12 Pattern of exogamy (endogamy): “[M]ost villagers consider themselves ultimately to be agnates and abide by the law of exogamy.” 4.13 What is the belief of the role of males in conception; is paternity partible? Are these “other fathers” recognized?: “Marriage in Rukuba society is unusual in that a Rukuban woman can marry more than once, and she is considered to be married to all her husbands even though she will live with only one at a time. A man might have more than one wife living with him at any time. Any children belong to the husband the mother claims is the father” (5p591). 4.14 What is the belief of the mother’s role in procreation exactly? (e.g., “receptacle in which fetus grows”): No evidence found 4.15 Is conception believed to be an incremental process (i.e., semen builds up over time)?: No evidence found 4.16 Occurrence of sexual coercion, rape: No evidence found of sexual coercion; however, there is a situation in which “a man abducts the wife of another, with her and her father’s consent” (2p39). After bestowing gifts upon the woman’s parents, the man is established as “co-husband”.2 4.17 Preferential category for spouse (e.g., cross cousin): No evidence found 4.18 Do females enjoy sexual freedoms?: “For premarital relations, however, each village was endogamous; every young girl had, prior to marriage, premarital relations with young men from other patrilines of the same village. No offspring could be borne of such unions; unwanted pregnancies were terminated by abortion. A girl could have premarital relations with only one man at a time, following the payment of a sort of “lover price." The relationship had to last at least six months, but it could continue for a longer period. A girl could have several of these unions in succession before she married out, around the age of 20.” 4.19 Evidence of giving gifts to extramarital partners or extramarital offspring: No evidence found 4.20 If mother dies, who raises children?: No evidence found 4.21 Adult sex ratio: number of adult males divided by number of (reproductive) females: No evidence found 4.22 Evidence for couvades: No evidence found 4.23 Different distinctions for potential fathers (e.g., lesser/younger vs. major/older): No evidence found 4.24 Kin avoidance and respect?: No evidence found 4.25 Patterns of descent (e.g., bilateral, matrilineal) for certain rights, names or associations: “Although descent is patrilineal, genealogies are not remembered after three or four generations. Patrilocality is very strong, 4.26 Incest avoidance rules: “…must avoid close relations by blood…” (2p40). 4.27 Is there a formal marriage ceremony?: No evidence found 4.28 In what way(s) does one get a name, change their name, and obtain another name?: No evidence found 4.29 Is marriage usually (or preferred to be) within community or outside community? (m/f difference?): “Marriage among the Rukuba has been examined only—and then not exhaustively—from the point of view of premarital sexual relations permitted between members of the same exogamous unit (iza): therefore a number of the features of the system are puzzling. There seem to be many restrictions affecting the choice of a mate among the Rukuba. Close relations among members of the eligible exogamous unit…are to be avoided, in the first place and, in the case of secondary wives, the wives of one’s fellow-villagers” (2p39). 4.30 Are marriages arranged? Who arranges (e.g., parents, close kin?)?: “For the purposes of marriage, the Rukuba population, as a whole, is divided into two exogamous moieties. According to the ideational model, each village may belong to either moiety, and there are approximately the same number of villages in each exogamous moiety. Each village is also exogamous, and every girl from one moiety must, by definition, marry into the other…a unique form of preferential marriage: the eldest girl of a set of uterine sisters was betrothed to the son of her mother's last lover. Subsequent sisters were also engaged to boys from their mother's natal village, the whole operation being a delayed exchange: all the daughters of a woman had to be married in their mother's natal village. This practice occurred in conjunction with another type of marriage. As soon as a girl was betrothed to her preferential mate, any man from other villages of the girl's opposite moiety could court her and she could choose one among them to become her first husband. Only 9 percent of the women had their preferential suitor as future husband. The remaining majority married first the man they had selected by free choice. The woman stayed with him for a month or two and was then escorted to the preferential suitor. The stay with him of one month was compulsory, after which the girl, now a spouse, could either remain with him or go back to the first, deserted husband. After a year, a woman could choose to remain with the husband with whom she stayed, to join the husband she previously deserted (preferential or free choice), or to select a new husband from the right moiety. All these marriages remained valid and a woman had the right to return to any of her husbands. Nowadays the woman spends the whole year with her free-choice husband and can remain with him if she likes or marry another husband. The minimal stay with a husband is a year, but a woman can stay as long as she wishes. There is no bride-wealth refund because the woman is still considered married to all her husbands, although she cohabits with only one at a time. In case of contested paternity rights, the child belongs to the husband the woman names as the father. When a woman with one child under 5 years of age moves from one husband to another, the new husband has to take care of the child, who will be sent back to his or her true father after the age of 5 to 6 years. A husband can have several wives living elsewhere, but he can also have several living with him at the same time. The proportion of men having two wives or more living together with him is only 28 percent of married men, the rest having only one. Many husbands remain wifeless while waiting for one of their wives to come back or trying to marry a new one.” 4.31 Evidence for conflict of interest over who marries who: No evidence found Warfare/homicide 4.14 Percent adult (male) deaths due to warfare: No evidence found 4.15 Outgroup vs ingroup cause of violent death: No evidence found 4.16 Reported causes of in-group and out-group killing: “Most intraethic conflicts erupted during communal hunts, over the sharing of game. They were followed by retaliatory raids, but such outbreaks were usually quieted quickly. Interethic conflicts flared up on the same occasions; there were mechanisms to make a truce, and relations rarely remained strained for long. The Rukuba victoriously repelled attacks from the Zaria Emirate's armies until the colonial era.” 4.17 Number, diversity and relationship with neighboring societies (external relations): “Formerly the Rukuba were famed as fighters, head-hunters and cannibals, and feared by their neighbours” (2p35). They face language barriers with their neighbors. 4.18 Cannibalism?: “The literature rather stresses the role of head-hunting and cannibalism among the Rukuba, but there seems to have been no tendency towards the resurgence of these during the years of British administration such as has been observed in some areas of Nigeria. A man who slew and adversary in battle did not take his victim’s head: the actual head-taking was done by a companion. Captured heads were hung from a tree, around which the women of the community performed a dance; no effort was made to preserve the skulls. Only the elders partook of the actual flesh of victims, though young men were given the broth to drink’’ (2p44). 5. Socio-Political organization and interaction 5.1 Mean local residential (village) group size: “The Rukuba are a patrivirilocal agriculturalist people grouped into twenty-four villages, each of them belonging to...a section. A section comprises a senior village and the dependent villages ultimately deriving from it. There are five such sections; each of them ideally comprises a senior village, which has the right to open the important Rukuba rituals, aso and izaru. The senior village performs some of the ceremonies ahead of the dependents, which follow in order of seniority. Each senior village is the arbitrator in case of intervillage disputes arising within the section when such disputes cannot be settled by the protagonists. Arbitration is asked for from the senior village. Thus, each section has arbitration mechanisms to cope with troubles concerning peoples or villages within it but there is no institutional mechanism to deal with troubles concerning people or villages of different sections. There are, however, two pantribal integrating devices that unite the Rukuba: the marriage system and the ritual system” (3p64). 5.2 Mobility pattern: (seasonality): No evidence found 5.3 Political system: (chiefs, clans etc, wealth or status classes): “Each village is divided into patrilineal clans, which have complementary duties at the village level. One clan provides the chief, and another is responsible for both the control of witchcraft and for calling big communal or intertribal hunts. Yet another clan is in charge of the well-being of all the uterine nephews and nieces of the village. Lesser offices such as rainmaker, rain appeaser, or master of the village drum can be the prerogatives of other clan chiefs or are simply vested in houses of clans that already have a more important office. Each clan chief hears intraclan civil disputes; if not successful, the case may be brought to the village chief. Interclan civil disputes are dealt with by the clan chiefs, assisted by the village chief. Criminal cases are investigated by the clan chief or, more often, the village chief.” “[S]upreme judicial authority seems to be vested in the village council: in Kakkek Village-Group there was only one court, the council of the hamlet of Egwa having no judicial powers; in Ujja, limited powers were delegated to the dependent village councils, though the village-area council remained paramount. Though some member of the council, usually the Univichi, was charged with producing the defendant and seeing that sentence was executed (being in effect ‘armed’ with ‘a band of young men’), it was not the council’s duty to seek out crime; on the other hand, in no case was summary justice authorized. According to Counsell, ‘The court had jurisdiction over all members of the community of which it was the tribunal whether the offence was committed within the community or outside it. Thus if a Kakkek man committed a crime in Ujja, he would be arrested by the Uijja authorities and the news sent to Kakkek. The Kakkek court would then pronounce judgment and sentence, and any fines or the proceeds of selling into slavery would belong to it, though some gift would be made to the Uijja court. In civil cases, the court in whose area the defendant lived would have jurisdiction. Sentences varied from a warning to selling into slavery: capital punishment was not usual, though it is recorded that a man of Kakkek who proved to be an incorrigible arsonist was himself burnt to death. The most serious offences were murder, burglary, and adultery (sexual relations between a man and a fellow-villager’s wife, according to Counsell): the punishment for these was selling into slavery. Arson was also a most serious offence, but there seem to have been a graded series of fines for the crime, exacted according to the record of the guilty party and the seriousness of the case; the ultimate punishment seems usually to have been selling into slavery and confiscation of the guilty party’s property. Witchcraft, too, had a graded series of punishments, beginning with burning the guilty party’s hands and feet, increased by fines, and culminating with selling into slavery. ‘Lesser offences such as theft, assault, and injury to property were punished by fines.’ Counsell adds: ‘Intention was taken largely into account; if there was no guilty intent there was no crime.’ For example, in a case of accidental homicide, ‘the slayer was only taken to the fetish-hut and ceremonially cleansed’; if hunger drove a man to steal, he was merely reminded that to ask for food was to be given it. Similarly, a case of assault with intent to kill is cited which resulted in the culprit’s sale as a slave. There were apparently two methods of ordeal. The commoner of these was to cut the throat of a fowl: if it fell forward dead, the accused was pronounced guilty; if it ran a few steps and fell with its feet in the air, he was innocent. Sasswood was administered only at Ishe (Bishi?); ‘a small hamlet of Kisanchi’ (actually a ward? of Bimban?): ‘important cases from other villages were sent for trial there.’ According to Counsell, a crime was primarily an offence against Katakuru, the high god, and the community which failed to bring the criminal to justice risked disaster wrought by supernatural means. Accordingly, the individual received no compensation for a wrong done him, apart from the restoration of stolen property, though he might be rewarded, in effect, for bringing his case to court: fines and the proceeds of the sale of slaves went largely to the heads of the community, who were equally presidents of the court. Another type of case is isolated by Counsell involving loans, the apportionment of inheritance, the adjustment of marriage payments, and the like: if these could not be settled by the compound-head or the wardhead, they were arbitrated by the hamlet or village council, whose Univichi was, again, empowered to enforce the council’s decision if necessary. The successful disputant usually rewarded the arbitrators” (2p44-45). 5.4 Post-marital residence: “[T]here is a separate hut for each adult female, whether married or not” (2p36). 5.5 Territoriality? (defined boundaries, active defense): “The Rukuba never acted as a coordinated unit against foreign enemies. After numerous administrative experiments carried out by the British, the Rukuba were finally united in a single district in 1936, and in the early 1950s they elected a single administrative chief, assisted by the village chiefs in council, section chiefs being the more prominent among them.” 5.6 Social interaction divisions? (age and sex): No evidence found 5.7 Special friendships/joking relationships: “[I]t happens more often than not that a village includes one or several groups of people from the opposite moiety. Such groups are always less populous than the main group of the other moiety and they lack political rights. Conceptually, they are seen as outsiders and they have a metaphorical status of ‘wives’ of the dominant exogamous moiety. For marriage purposes, they are from the opposite moiety and form sui generis wife-taking units. If the people of these groups are the metaphorical ‘wives’ of the dominant group of the other moiety, the latter, conversely, are deemed to be the ‘husbands’ of the members of such minority groups. This conjugal analogy leads to elaborate joking relationships between ‘wives’ and ‘husbands’; boisterous relations pertain between any two men of the opposite moiety within the village, but it is not a relation entered into by both moieties qua moieties; it is restricted to the village where the ‘wives’ act as ritual assistants to designate such people” (3p66). 5.8 Village and house organization: “Each smaller unit of the family seems to occupy a walled-off quarter of the compound; generally, the horses are stabled together at the entrance to the ‘cell’ occupied by the compound.-head and his immediate dependents, and in the stall the more venerable of the elders of the compound sleep on beds of mud or planks. The men and women of the compound maintain separate granaries…” (2p36). “Rukuba villages are generally comprised of a core nucleus densely populated with outlying settlements, which were originally dispersed on rocky eminences around the core nucleus. This pattern slowly changed in the 1950s, when people started migrating to their farms situated in the plains and valleys at the bottom of the rocky outcrops. Village populations range between seventy residents in the smallest ones to more than a thousand in the largest. Manured gardens, often fenced with high euphorbias, are close to the houses. A belt of small fields, usually cultivated by women, surrounds the village; the small fields are less manured, and some remain fallow for several years. Bush farms constitute another field category, sometimes at a distance of several kilometers from the village. People with faraway fields spend several weeks there in the rainy season. Such fields are never manured, except nowadays by an occasional Fulani cattle camp.” 5.9 Specialized village structures (mens’ houses): The Rukuba had round huts made of mud with “conical thatched roofs, huddled together in the clefts and hollows of the rocky escarpment.” “The typical family household consists of a walled compound of round mud huts. The entrance, which is the kitchen and/or pounding house, is used by all the women of the compound. The owner of the house has his own room; each wife has hers as well, as do the nubile daughters. Married sons establish similar compounds very close to the parental house, one married son remaining very often within the paternal enclosure. Square huts are also to be found, but corrugated iron roofs are exceptional.” 5.10 Sleep in hammocks or on ground or elsewhere?: “The sleeping-huts have massive mud platforms for beds, with fireplaces built into them” (2p36). 5.11 Social organization, clans, moieties, lineages, etc: “The Rukuba constitute a federation of villages, each village being a chiefdom. Several villages form a section comprised of villages that ultimately claim to have originated from the section head village. There are five such sections. The section head village has important ritual duties; its chief reckons the dates of all important panethnic rituals. Politically speaking, this chief can arbitrate conflicts between villages of his section if the involved parties ask him to do so. Two head villages have a more prominent ritual role in organizing, in turn, the kugo initiation ritual. Interethic relations were rather particularistic, some villages or even clans being either "brothers" or enemies of other neighboring ethnic groups.” 5.12 Trade: “There was a small amount of trade with neighboring peoples. Imports were not necessary, except for salt, which came from Zaria Emirate through the intermediary of adjacent ethnic groups. Markets were unknown until the British introduced them. Eastern Rukuba go directly to the Jos main market to trade but attend the local markets to drink sorghum beer.” “Boys undergo a compulsory three-stage initiation following a complex calendar encompassing all the villages in turn. The first stage is normally Icugo, a ritual that initiates and terminates an entire ten to twelve years’ initiation cycle. The second state is izaru, the circumcision ceremony that every boy attends before he is 7. Nowadays, however, the actual circumcision is practiced soon after birth. The third state, aso, makes the boy ritually adult before he is 12. He is then taught the principal rules regarding marriage and adultery. No initiation pertains to girls, although they play a symbolic role in boys’ initiation ceremonies.” 6.0 Time allocation to RCR 6.1 Specialization (shamans and medicine): “The Rukuba have two kinds of local doctors: those curing with herbs and plants, and diviners. No special power is vested in the first type, whereas the second is credited with spiritual powers. The most sought-after diviners, however, come from neighboring tribes, and Rukuba diviners are, conversely, more known across the ethnic border. Some specialize in treating illnesses coming from the maternal side of the patient.” “Traditional curing goes side by side with other methods of treating disease. Western medicines are eagerly sought from the missionaries and a dispensary that is well attended. Hospitals in the nearby town of Jos are frequently visited, especially by Christians.” “According to Counsell, specialists in medical practice are the only full-time craftsmen apart from smiths, numbering ‘not more than 20 all told,’ who ‘must be prepared to deal with anything from tooth-extraction to witchcraft,’ including abortion. Methods of abortion include ‘medicine to drink,’ prepared from roots of a tree; massage, often violent, if medicine fails; and finally, in extreme cases, ‘actual extraction.’ In many of the cases which have come to the attention of the Administration, the girl has died. ‘Persons practising witchcraft may be spotted by those having the power to do so, and are accused before the religious heads, who would deal with them according to the measure of evil they had caused.’ In general, it is said, ‘if a doctor’s son shows promise in the profession he will be trained to succeed him; otherwise, some other member of the family is taught the mysteries of the craft’” 6.2 Stimulants: “The most important ceremonies are connected with initiations during which numerous goats are slaughtered.” 6.3 Passage rituals (birth, death, puberty, seasonal): “Boys undergo a compulsory three-stage initiation following a complex calendar encompassing all the villages in turn. The first stage is normally Icugo, a ritual that initiates and terminates an entire ten to twelve years’ initiation cycle. The second state is izaru, the circumcision ceremony that every boy attends before he is 7. Nowadays, however, the actual circumcision is practiced soon after birth. The third state, aso, makes the boy ritually adult before he is 12. He is then taught the principal rules regarding marriage and adultery. No initiation pertains to girls, although they play a symbolic role in boys’ initiation ceremonies.” “Persons practising witchcraft may be spotted by those having the power to do so, and are accused before the religious heads, who would deal with them according to the measure of evil they had caused.’ In general, it is said, ‘if a doctor’s son shows promise in the profession he will be trained to succeed him; otherwise, some other member of the family is taught the mysteries of the craft’” 6.0 Time allocation to RCR 6.1 Specialization (shamans and medicine): “The Rukuba have two kinds of local doctors: those curing with herbs and plants, and diviners. No special power is vested in the first type, whereas the second is credited with spiritual powers. The most sought-after diviners, however, come from neighboring tribes, and Rukuba diviners are, conversely, more known across the ethnic border. Some specialize in treating illnesses coming from the maternal side of the patient.” “Traditional curing goes side by side with other methods of treating disease. Western medicines are eagerly sought from the missionaries and a dispensary that is well attended. Hospitals in the nearby town of Jos are frequently visited, especially by Christians.” “According to Counsell, specialists in medical practice are the only full-time craftsmen apart from smiths, numbering ‘not more than 20 all told,’ who ‘must be prepared to deal with anything from tooth-extraction to witchcraft,’ including abortion. Methods of abortion include ‘medicine to drink,’ prepared from roots of a tree; massage, often violent, if medicine fails; and finally, in extreme cases, ‘actual extraction.’ In many of the cases which have come to the attention of the Administration, the girl has died. ‘Persons practising witchcraft may be spotted by those having the power to do so, and are accused before the religious heads, who would deal with them according to the measure of evil they had caused.’ In general, it is said, ‘if a doctor’s son shows promise in the profession he will be trained to succeed him; otherwise, some other member of the family is taught the mysteries of the craft’” 6.2 Stimulants: “The most important ceremonies are connected with initiations during which numerous goats are slaughtered.” Asau marks the threshold of adulthood…[T]he most pressing reason for separating the two appears to be economic, and those who have passed as it were undifferentiated through Kugu seem in effect to be stratified according to the speed with which they complete Asau thereafter. Kugu appears to be primarily the property of the Kishin branch of the tribe, whose villages form a unit with respect to Kugu: it is performed at 7-year intervals alternately at Kakkek and Kishi, and in intervening years, also at 7-year intervals, by other villages (unspecified). Counsell stresses that other villages performing Kugu recognize the primacy of the Kishin rites, and only at Kishi and Kakkek are they performed unabbreviated. (Kugu has never been performed at Ujja, whose Utu was for a period thought to be paramount among Rukuba chiefs, and youths of that village commonly attend the rites at Kakkek and Kishi.) The essential cult-object, which Ames believes to be an iron mask, but the nature of which native informants apparently deem too awful to specify, is kept at ‘Kigbo in Zaria’ (a ward of Kishi? Counsell suggests that ancestral Gba, in Bauchi, is meant); in the intervals between its use by Kishi and Kakkek it may be used by other villages, fetched at night from Kigbo by the Utufichi…Asau (aso) is celebrated at intervals of two or three years—always in the dry season immediately following Kugu. Those who pass through Kugu together are conceded by native informants to form a group, but the group appears to have no particular function; and it is stressed that all members of such a group do not necessarily pass through Asau together, as each boy submitting himself to these rites must produce an additional goat for slaughter and a considerable quantity of beer. The boys assembled for Asau spend a night with an adult woman; the following day, according to Ames, they are taken to a grove apart and harangued on the subject of the sanctity of the rules governing marriage, after which they are given goatskins to wear, may be outfitted with iron greaves, and are eligible to contract the izni relationship and marriage. Ames adds that a youth who has completed Asau can also ‘himself perform tsafi for various purposes, such as for the success of his millet crop’… Further, the initiated appear to have first call on meat supplies, while the uninitiated (including women) may be forced to do without. There seems to be a fixed order in which villages perform Asau, but this is only partially known (Ujja-Kakkek-Ohit-?), and it appears that Asau is equally the property of every village and hamlet. It is probably not a function of the ward, although it is nowhere made clear that Utu and Univichi, whose absence in effect defines a community as a ward, perform any role at Asau” (2p43-44). “The cycle of rites which attend a boy’s growth is treated at some length in the literature. Ames states that septennial circumcision rites, termed Izaru, are held simultaneously in all Rukuba villages, but Counsell found no trace of them: according to Counsell, circumcision was formerly a feature of Kugu, but is now performed at Kugu only token-wise on a single representative from each compound, all others being circumcised shortly after birth. Meek’s report that circumcision, performed in the home compound, is preceded by a veritable baptismal ceremony, with head shaving, in a retreat apart from the village, does not entirely clarify the situation on this point” (2p42-43). 6.4 Other rituals: “The high god of the Rukuba is Katakuru, and Counsell states that the primary function of the Utu is to ‘intercede with Katakuru on behalf of the people.’ He adds, ‘there are numerous ceremonies and festivals concerned with rain-making and fertility which the Utu and other religious heads practise on behalf of the community.’ Each Utu, he points out, has a ritual millet farm to tend, though the associated rites are not described, and their precise significance is not suggested. An Utu’s first seven years in office are considered probationary: drought, pestilence or a shortage of wives during this period would prove him unacceptable to Katakuru; a single great disaster might be enough to bring about his deposition and exile, if he were divined to have caused it by supernatural means (witchcraft or sorcery—no distinction between these two seems to be recognized in the literature). At Kakkek, the period of probation is said to be six Kugu festivals, or from 36 to 42 years, so that very few Village Headmen are actually confirmed. After the initial period, it is said, the Utu of Ohit cannot be removed except by prayer directed to Katakuru, but in other villages means appear to exist by which an incorrigible Utu can be dealt with, though these means may be rather more formal than any to which it is suggested recourse may be had during the early period” (2p41). “The role of the Utu as rain-maker has been mentioned: the rites at Ujja only are described in the literature. Ames believed that the Utu Ujja was rain-maker for the entire Rukuba community, and Counsell seems to confirm this view, though one may infer from his report that the Ujja rain-cult is only first among essential equals. According to Ames, the rites at Ujja are annual. A white goat, a white mare and a white fowl are sacrificed at a shrine on a hill near the village; then two handfuls of earth, said to represent Vom (Vwang) of the Birom and Ujja, are mixed in a pot and placed in a cave nearby, where the longest bamboo pole available is kept. After prayers, the bamboo, to the end of which a charm is tied in a piece of cloth, is taken to another hut at the foot of the hill, planted in a hole there and fixed in with blood from the animals slaughtered. Then the Utu mounts a horse, which has been held in readiness, and rides full speed to his compound, and the crowd disperses to avoid the downpour to follow. The earth of Vom is said to be female, as the river there is termed the Mother of Waters; the river at Ujja is the Father of Waters, and the soil, male: the rain is the offspring of their union. In former times, it is said, earth was actually brought from Vwang for the ceremony, but this is no longer done” (2p42). 6.5 Myths (Creation): “A Kuba myth tells us that the niece of the cultural hero Woot gave birth to a lamb at the very moment when the dynasty’s founder voluntarily exiled himself after being blamed by his people for his incest he committed secretly with his sister” (6p102). 6.6 Cultural material (art, music, games): “There is no art in the Western sense of the word. The Rukuba decorate their village ritual hut, their village sacred pots and drums, and, in one village only, there is a septennial private display of decorated objects for the benefit of people organizing the ritual.” fourthly, “They excel in music and dancing. Their chief instruments are pipes, usually made of cornstalks, and the sort of ‘reed-harp’—as it is commonly termed, actually constructed on the principle of the zither—widely distributed in the Plateau Area” (2p36). 6.7 Sex differences in RCR: “Women have no share in the ritual…, though rites are performed on them at the time of their first pregnancy, and if they should see an ant-eater they are taken to the door of the fetish-hut and ceremonially cleansed” (2p44). “Agricultural rites are not spectacular, although each clan chief has to undertake them. The most secret rituals are those connected with the person of the chief, but most Rukuba men know them. Ritual knowledge can be shared by all men, but women are supposed to know nothing about it.” 6.8 Missionary effect: No evidence found 6.9 RCR revival: “It is primarily in small societies, such as the Rukuba (Nigeria) that the symbolic structure of this political institution is most evident. Each Rukuba village constitutes an autonomous political unit. However, Muller convincingly shows that its chief (utu) has all the characteristics ‘of the sovereigns referred to in the literature as divine kings’. If his mystical power proves ineffectual in coping with any kind of catastrophe, he is deposed. Though he is not put to death, as the classical Frazerian schema would have it, Muller demonstrates that the theme of regicide haunts Rukuba ritual thought and practice. The nominating procedures for a new village chief vary, but they are always shrouded in mystery. The ideal candidate should cut a fine figure and speak with ease and authority, and also respect the customs. Moreover, he should possess a mystical power the Rukuba call the Eye; as should the Blacksmith, the clan chief and the diviner. However, the village chief differs from the other possessors of the Eye because of the remarkable characteristics conferred upon him by the installation rites. The candidate elected from the clan in power, is truly ‘bound’ to the chieftainship. He hides in the home of his mother’s brother and his head is shaved as if he were “in mourning for himself”, for his agnates have symbolically killed him. In the end, the uncle gives back his nephew, who is ‘resuscitated’ like a child emerging from initiation. He then prepares to bear the ‘burden of chieftainship’ by drinking beer from the skull of one of the previous chiefs. In three leading villages, the chief is symbolically put to death during his enthronement through a substitute human victim: the ritual organisers seize and smother a sickly newborn baby belonging to the chief’s clan. Then a ram is immolated. A bit of the infant’s flesh is secretly added to a few pieces of the ram which are cooked and then eaten by the chief. He is now anthropophagous, without realising it. He becomes dangerous; his mystical power can infect those who eat or drink from the same receptacle as he” (6p99). 6.10 Death and afterlife beliefs: “Chiefs, clan chiefs, blacksmiths, diviners, and witches reincarnate. Their souls stay in a shooting star, or somewhere else, before reentering a pregnant woman’s womb. Other people’s souls simply disappear; their influence may remain, temporarily, through their bones or through curses uttered when they were alive. Burial ceremonies and mourning practices are aimed at getting rid of the dead as completely and as soon as possible.” 6.11 Taboo of naming dead people?: No evidence found 6.12 Is there teknonymy?: “Chiefs of Ujja are reincarnated; on the death of an Utu, his spirit may find temporary lodging in a star of a bird; when a woman in the compound of the Utu, attractive to the spirit, conceives, the spirit enters her child. The elders of the chiefly family are able to divine the reincarnation, but hide their intelligence from the reigning Utu, lest he should become jealous and put the infant to death: the Utu, thus, never knows who his successor is to be. The generality of these beliefs among the Rukuba is not known” (2p41). 6.13 Briefly describe religion (animism, ancestor worship, deism, magic, totems etc.): “Ancestor worship is said to be a factor of group-life at every level: each compound, ward and village has its own ancestral shrine. Counsell minimizes the ancestral cult in general, but Ames stresses the role of the Utu of Ujja (Achaka) as the high priest of the ancestral cult: he has the power to ‘commune with the ancestral spirits, which are said to dwell in his house and become visible at night only to him and members of his household.’ The ancestral spirits of every kin-group must apparently be approached through the Utu, who retires to the family shrine of the individual concerned when representations are to be made. Counsell, though generalizing that ‘the Utu invokes his ancestors for the assistance of the whole community,’ states that the head of the compound (the eldest member of the senior branch of the family) needs no intermediary at the shrine in his own compound” (2p41). “The Rukuba believe that the prosperity and the well-being of the land and people rests in the physical person of the village chief, who is a scapegoat. If prosperity fails, or if drought, locust invasions, plagues, defeats in war, or deep dissensions between the villagers occur, the chief is deposed and replaced to remedy the situation. The village chief is a variation of James G. Frazer's "divine king"; he is forced to commit a transgression, which makes him good and bad at the same time. Like any of the other divine kings, his bad part is sacrificed by proxy at regular times and one of his alter egos is also killed in the two prominent ritual villages, the beneficial effect being shared by the other villages as well. An individual's well-being also depends on his "double" residing in his mother's natal village, under the care of a clan chief. The High God is beyond reach, and ancestors play almost no role. No more than 4 to 5 percent of the Rukuba are Christians (Evangelical Church of West Africa), but they constitute the most politically active and "modernist” group. Islam has made no inroad.” 7. Adornment 7.1 Body paint: Women have “no facial markings, but body-marks are usual and consist of faint designs on chest and stomach” (2p36). 7.2 Piercings: No evidence found 7.3 Haircut: No evidence found 7.4 Scarification: No evidence found 7.5 Adornment (beads, feathers, lip plates, etc.): “…it is suggested that the Rukuba have wrought-iron ‘fetish objects’—possibly masks—manufactured perhaps in the more or less distant past, though no European has ever viewed these” (2p35). As blacksmiths, they manufactured rough metal bracelets.2 7.6 Ceremonial/Ritual adornment: No evidence found 7.7 Sex differences in adornment: “Adult males usually wear a leather loin-covering and a tanned goat-skin cape over one shoulder and under the opposite arm, with a metal fastening in front. Men may also wear spurred iron greaves, but these must be put on by a smith and are at times painful to wear, and the suggestion is that they may be passing with the decay of intertribal warfare. The plaited penis-sheath is common and is donned when puberty is reached. Younger men and boys may wear loin-cloths, but must dress in skins on ceremonial occasions. When courting, these commonly oil their bodies with shea-butter or groundnut oil, and adorn themselves with a stripe of red ochre from ear to ear across the forehead at the hairline” (2p36). 8. Kinship systems 8.1 Sibling classification system: No evidence found 8.2 Sororate, levirate: “A widow may marry her late husband’s brother (or, according to Meek, his father or uncle) without making further payments, or she may—after a year has passed—choose another husband, who would pay her parents, however, rather than her deceased husband’s kin. In the latter case, apparently, she may choose not to join her new husband in his household, but maintain her own, presumably on the lands falling to her sons, where her husband may visit her” (2p40). 8.3 Other notable kinship typology, especially cross-cousin (MBD/FZD) typology (Crow/Hawaiian/Omaha etc.): “The Rukuba use Hawaiian cousin terminology with bifurcate-merging terms for maternal uncles.” 9. Other interesting cultural features (list them): - “The restrictions on a man’s choice of a paramour appear to be in the main complementary to those affecting his choice of wife: generally, he will sleep with a girl of his own village, though he must avoid close relations by blood (here again, as ibigyen seems to comprehend both fellow-villagers and relations of all sorts and degrees, the confines of eligibility in native terms are somewhat obscure). For his ‘rights’ a lover pays the girl’s parents ‘anything from a goat or a hoe to two goats and a hoe,’ depending apparently to some extent on the duration of the relationship, for the lover can expect a partial refund if the girl turns him away for another lover or for a husband: a girl may not have more than one lover at a time, but she ‘may have several…before she marries, and her parents reap great profits therefrom. This relationship has one considerable complication from the point of view of the Rukuba community: the position of a child conceived by an unmarried girl seems to be regarded as quite impossible, for what reason it is not stated, and abortion is attempted; if it is unsuccessful the child is killed at birth” (2p40). - “According to E. H. M. Counsell…the Rukuba are a vigorous people of fine physique and impressive as regards ‘the numbers of active old men’—these, he adds, ‘and others…take an active interest in their own affairs, have a clear and intelligent idea of what they want, and no fear of speaking out’” (2p35). Numbered references 1. Ethnologue.com 4. Everyculture.com
Multiphase Aluminum A356 Foam Formation Process Simulation Using Lattice Boltzmann Method Mojtaba Barzegari\textsuperscript{a,}, Hossein Bayani\textsuperscript{b}, Seyyed Mohammad Hosein Mirbagheri\textsuperscript{b}, Hasan Shetabivash\textsuperscript{c} \textsuperscript{a}Department of Biomedical Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran \textsuperscript{b}Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran \textsuperscript{c}Department of Mechanical and Industrial Engineering, Concordia University, Montreal, Quebec, Canada Abstract Shan-Chen model is a numerical scheme to simulate multiphase fluid flows using Lattice Boltzmann approach. The original Shan-Chen model suffers from inability to accurately predict behavior of air bubbles interacting in a non-aqueous fluid. In the present study, we extended the Shan-Chen model to take the effect of the attraction-repulsion barriers among bubbles into account. The proposed model corrects the interaction and coalescence criterion of the original Shan-Chen scheme in order to have a more accurate simulation of bubbles morphology in a metal foam. The model is based on forming a thin film (narrow channel) between merging bubbles during growth. Rupturing of the film occurs when an oscillation in velocity and pressure arises inside the channel followed by merging of the bubbles. Comparing numerical results obtained from proposed model with metallography images for aluminum A356 demonstrated a good consistency in mean bubble size and bubbles distribution. Keywords: Metal Foam, Aluminum A356, Form Grip, Lattice Boltzmann Method, Shan-Chen Model, Multiphase Fluid Dynamics 1. Introduction Demanding for advanced materials are increasing rapidly via new technologies. Closed cell metal foams gained a lot of interest as one of the major branches of advanced materials due to their unique physical and mechanical properties, including high specific strength and compressibility along with good energy absorption capability [1, 2, 3, 4]. Despite the advantages, the employment of metal foams in industrial applications is limited due to the inhomogeneity of the structure which results in the deviation of the mechanical properties of the foams from what predicted by the scaling relations. This is mainly due to the morphological defects such as missing or wavy distortions of the cell walls and non-uniform shape and size of the cells which results in poor reproducibility of foam structures [5]. In metals, unlike ionic liquids, the formation mechanisms of metal foam has not yet fully understood [5]. Bubble stability is the primitive challenge in understanding the mechanism of metal foam formation. A variety of studies and researches have been performed by scientists in order to investigate and analyze the parameters affecting bubble stabilization [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]. Most of the investigations have focused on formation of single bubble in ionic liquid environment, especially water, with no impurity [8, 10, 11, 12, 13, 14]. However, even in the purest condition, molten metal contains dozens of different impurities. Another important issue which has been neglected during various studies is the multi-bubble nature of metal foam formation process, which mostly appears in bubbles interactions. In addition, due to the presence of metallic bond in metal melt, there is no ionic or polar attraction and repulsion forces, which causes a different behavior of the liquid-gas interface in metal melts in comparison with aqueous solutions [4, 5, 6, 7]. In order to have a computational study on metal foam formation process, a basic understanding of bubble stability conditions in the presence of particles is required. Therefore, a computational model based on known dynamics of bubbles and improving it using the computational-experimental approach has to be built, which is accomplished by adding some constraints that are focused on the boundary of each bubble according to available theories and verify the selected ones using an experiment [5]. Most of the studies in the field of bubble dynamics investigated single bubble dynamics in aqueous solutions or water based liquids and only a few are conducted to study multi bubble dynamics and foam formation process. Chahine [10] studied the dynamics of clouds of bubbles via both analytical technique and numerical simulation using 3D Boundary Element Method (BEM). They also studied the behavior of bubbles in a non-uniform flow field and their response to flow. Chahine [11] investigated influence flow field to interaction of bubbles. Ida [12] conducted a mathematical modeling using a nonlinear multi-bubble model from pressure pulses perspective. Bermond et al. [13] performed an outstanding computational investigation on bubble interactions and validated it using a novel experimental procedure. The dynamics of bubbles in that research was based on Rayleigh-Plesset equation. Kim et al. presented an Immersed Boundary Method (IBM) to simulate and predict the 2D structure of a dry foam. This method allows one to study pressure equilibrium in non-conventional approach. In their model, a set of thin boundaries partition the gas into discrete cells or bubbles [16]. The Lattice Boltzmann (LB) simulation has been used extensively to simulate the kinetic effects on bubbles [17]. Advantage of LB approach lies in the fact that there are no global systems of equations which have to be solved. Besides, boundaries in simulation domain do not have an effective impact on the computation time. These features are essential for foam formation simulation regarding the complex internal structure of foams. Andrel et al. [18] used Lattice Boltzmann to simulate flow in a simplified single phase model as an alternative to a liquid-gas two phase model to analyze bubble interaction in protein foams in order to determine bubble coalescence conditions. Leung et al. [19] studied bubbles nucleation, growth, stability conditions and interaction in plastic foam processing. Beugre et al. [20] developed a 3D Lattice Boltzmann code to simulate fluid flow in metal foam. Pressure drop was the criteria used to compare the obtained results with experimental measurements. Computer aided X-ray microtomography was used to produce the 3D geometry of metal foam imported in LB simulation. They improved the computed geometry of the metal foam later with more advanced techniques in order to obtain better results. In this study we constructed a hybrid experimental-computational model to predict the structure of a two-dimensional closed-cell aluminum foam. Most of the simulations conducted in this field are based on single phase models, while a two-phase computational model is adopted in the present study. To this end, a modified and improved Shan-Chen model is developed for multiphase simulations. Besides, a novel boundary condition is utilized to simulate oxide network particles’ effect on the interaction of two bubbles. This method can be extended to account for a larger number of bubbles in order to simulate metallic foams. The proposed model is created based on an experimental procedure and actual samples’ structures. Moreover, some additional phenomena such as random nucleation, growth, coalescence, and aging of bubbles are also developed in this model. 2. Mathematical Modeling It is assumed that there is no variation in liquid temperature during foaming process, and the fluid flow is considered to be incompressible. Consequently, conservation of mass and momentum in a single phase continuum can be written as follows [22]: \[ \nabla \cdot \mathbf{u} = 0 \quad (1) \] \[ \frac{\partial \mathbf{u}}{\partial t} + (\nabla \cdot \mathbf{u}) \mathbf{u} = -\frac{1}{\rho} \nabla p + \nu \nabla^2 \mathbf{u} + g \quad (2) \] where \( t, \mathbf{u}, p, \nu, g \) are time, velocity, pressure, density, kinematic viscosity and gravity, respectively. In addition to conservation equations, gas pressure \((P_i)\) in bubble \(i\) could be expressed by ideal gas equation [8]: \[ P_i = \frac{n_i R T}{V_i} \quad (3) \] where \( R \) is gas constant, \( n_i \) gas mole, \( T \) temperature and \( V_i \) is volume of bubble \(i\). Gas and liquid were coupled at the interface by momentum balance and controlled by \( \Gamma \) parameter. For having a stable bubble, velocity of fluid and gas must be equal at the interface. \[ v_G(x) = v_F(x) \quad \forall x \in \Gamma \quad (4) \] In order to estimate the pressure during the growth or expansion of the bubble, the kinetics of expansion of a single bubble of radius \( R \) in an incompressible fluid with viscosity of \( \rho \) and pressure \( p_0 \) is considered as basic calculations and due to the symmetry of the problem, the NSE equation can be reduced to Rayleigh equation[8] in spherical coordinates. Thus the bubble growth with radius \( R \) can be calculated from Eq. 5. \[ \rho R \frac{3}{2} \frac{dR}{dt} + 4 \rho \nu \frac{R}{R} + \frac{2 \sigma}{R} = p_i - p_0 \quad (5) \] where \( \rho \) is \( \frac{\partial \rho}{\partial x} \) and \( \rho \) is \( \frac{\partial \rho}{\partial x} \). Each of the four terms of the Eq. 5 from left to right represents the excess bubble pressure, capillary pressure, viscous pressure and inertia pressure where \( p_i \) denotes the bubble pressure and \( \sigma \) is the surface tension. The Rayleigh equation expresses equilibrium between inertia, viscous and capillary forces, which prevent bubble expansion. However, in practice these forces will play a major role that is unclear and entirely depends on foam material and process parameters [4]. In this study it is assumed that blowing agent with specified weight percent was added to molten metal, uniformly distributed and dissolved by stirring. Then micro bubbles were abruptly produced by dissolution reaction of blowing agent in throughout the domain. Nucleation occurs in random points in the domain. After nucleation, bubble growth will begin. For growth modeling in each time step, gas will be added by virtual blowing agent (proportional to blowing agent weight and gas production rate) in each bubble, and then the bubble volume will be increased due to the pressure balance. Gas blowing or growth will continue until all virtual blowing agent gases are added to the domain. Other phenomena, such as drainage and wall rupture are considered in growth process by bubble equilibrium equations. Condition of wall rupture could be added as an experimental or a mathematical criterion. One would consider this condition experimentally. For example, if the cell wall thickness falls below a critical thickness (which is a material characteristic), cell wall rupture will occur. This critical number for aluminum melt is reported as 50μm, determined by X-ray radiography [6]. In this study, a computational criterion will be obtained from second derivative of pressure (∇²p). Hydrodynamics, gas release and diffusion are necessary for the foaming stage. The blowing gas solubility in the fluid is finite. The gas concentration in the fluid can be calculated by the diffusion equation: \[ \partial_t c + v \cdot \nabla c - \nabla (D \nabla c) = Q \] (6) where \( c = c(x,t) \) is concentration field of dissolved gas, \( D \) gas diffusion constant and \( Q = Q(x,t) \) is source term. The source term \( (Q) \) describes the blowing agent decomposition. There are two key points which have to be considered. One is gas solubility and the other is gas diffusion distance. In this study the concentration of dissolved hydrogen in molten and solid aluminum (C) is calculated from Eq. 7 and Eq. 8 respectively [4]: \[ C = 5.84 \text{ cm}^3 \text{ g}^{-1} \exp\left(-\frac{6357K}{T}\right) \sqrt{\frac{p}{\text{bar}}} \] (7) \[ C = 0.25 \text{ cm}^3 \text{ g}^{-1} \exp\left(-\frac{5941K}{T}\right) \sqrt{\frac{p}{\text{bar}}} \] (8) Diffusion distance \( \delta^{diff} \) is calculated from Eq. 9 where \( D \) denotes the diffusion coefficient and \( t \) the characteristic time [4]: \[ \delta^{diff} = \sqrt{4Dt} \] (9) The diffusion length is a measure for the region of influence of a blowing agent particle. For example, if \( \delta^{diff} \) is significantly larger than the mean particle distance, then a strong mutual influence has to be expected. The diffusion length is a measure for the region of influence of a blowing agent particle. In this study, diffusion coefficient of hydrogen in aluminum is calculated from Eq. 10 [4]: \[ D = D_0 \exp\left(-\frac{H}{RT}\right) = \left\{ \begin{array}{ll} 3.810^{-6} \text{ m}^2/\text{s} & \exp\left(-\frac{1926kJ/mol}{RT}\right) \end{array} \right\} 1.110^{-5} \text{ m}^2/\text{s} & \exp\left(-\frac{4098kJ/mol}{RT}\right) \] (10) where \( D_0 \) is a constant, \( R \) is the gas constant, \( T \) is the temperature and \( H \) the activation enthalpy. From Eq. 10, the diffusion coefficient at 700 °C is \( D_{700°C} = 3.51 \times 10^{-7} \text{ m}^2/\text{s} \) and diffusion length of hydrogen is 374μm. This length is small compared to the overall dimension of casting. Thus, gas concentration uniformity cannot be expected. Consequently, inhomogeneous distribution of blowing agent in melt will lead to non-uniform porosity. Experimental observations have confirmed this theory [4]. 2.1. Numerical Model 2.1.1. Lattice Boltzmann approach The LB method has shown to be suitable for foam formation problems [23]. Random micro bubbles in a virtual medium nucleate and interact within a set of rules. If correct physics is applied in the simulation, spontaneous hydrodynamic behavior can be expected. It can be said that LB method is a mesoscopic approach that is between macroscopic CFD approaches and microscopic molecular dynamics. Many multiphase models exist that use the LB method, such as Immiscible CFD (ILBM) [24] Shan-Chen Model [25, 26], Free energy model [27, 28], Chromodynamic model [29] and HSD model [30]. LB method models fluid dynamics by evaluating particle distribution function \( f(x,v,t) \) at each lattice point, where \( f \) is the probability of finding a moving fluid particle with velocity \( v \) at point \( x \) and time \( t \). By knowing \( f \), one could get the values of density and momentum. The distribution function used in LB method, \( f_i \), is a discretized form of the main continues function. Discretization means dividing the space into a finite number of lattices in order to present different parameters on these points, e.g. velocities could be evaluated by displacement vectors as \((\delta t, \delta x)\) where \((\delta t)\) is time step and \(i\) is direction displacement. At each lattice point, different sets of distribution function would be defined. Two mostly used functions are \( f \) and \( h \). The \( f \) function models mass and momentum transports and the \( h \) function perform energy transport modeling. The macroscopic parameters are given by aggregating these distribution functions [31]: \[ \rho = \sum_i f_i, \quad \rho u = \sum_i e_i f_i, \quad E = \sum_i h_i \] (11) where \( \rho \) is the density, \( u \) the macroscopic velocity and \( E \) the energy density. As we have neglected thermal perturbation and solidification of liquid phase in present study, the energy transportations and its related functions will not be discussed further here. The displacement of distributions is summarized by the equations of motion [32]: \[ f_i (x + e_i t + \Delta t) - f_i (x, t) = \frac{\Delta t}{\tau_f} \left( f_i^eq (x, t) \right) + F_i \] (12) where \( f_i(x,t) \) is the density distribution function in \( i \) direction. In order to model external forces such as gravity, one would use [32]: \[ F_i = W_i \rho \left[ \frac{(e_i - u)}{c_i^2} + \frac{(e_i \cdot u)}{c_i^2} \right] \cdot g \] (13) \[ f_i^eq (x, t) = w_i \rho \left[ 1 + \frac{(e_i \cdot u)}{c_i^2} + \frac{(e_i \cdot u)^2}{2c_i^2} - \frac{u^2}{2c_i^2} \right] \] (14) For a two dimensional D2Q9 model (2D with 9 velocity directions), the velocity direction \( \mathbf{e}_i \) and the weight \( \omega_i \) are given by [32]: \[ \mathbf{e}_i = \begin{cases} (0, 0) , & i = 0 \\ (\pm c, 0) , (0, \pm c) , & i = 1, \ldots , 4 \\ (\pm c, \pm c) , & i = 5, \ldots , 8 \end{cases} \] (15) \[ \omega_i = \begin{cases} 4/9 , & i = 0 \\ 1/9 , & i = 1, \ldots , 4 \\ 1/36 , & i = 5, \ldots , 8 \end{cases} \] (16) The viscosity \( \nu \) is given by: \[ v = c_s^2 \Delta t (\tau_f - 0.5) \] (17) where \( \tau_f \) is the relaxation time for velocity field in dimension-less form. Equation of motion (Eq. 12) is solved by LBM in two steps, as noted earlier, known as collision and streaming [32]: \[ f_i^{\text{out}}(x, t) = f_i^{\text{in}}(x, t) + \frac{\Delta t}{\tau_f} (f_i^{\text{eq}}(x, t) - f_i^{\text{in}}(x, t)) + F_i \] (18) \[ f_i^{\text{in}}(x + e_i, t + \Delta t) = f_i^{\text{out}}(x, t) \] (19) where \( f_i^{\text{out}} \) and \( f_i^{\text{in}} \) are outgoing (after collision) and incoming (before collision) distribution functions respectively. 2.1.2. Shan-Chen model Shan-Chen model is based on incorporating long-range attractive forces (\( \mathbf{F} \)) between distribution functions. In the original Shan-Chen model, the interacting force is approximated using the following equation [25, 26]: \[ F(x) \equiv -\frac{\partial^2 b}{\partial \psi} g \nabla \psi(x) \] (20) where \( b \) is the number of nearest sites with equal distance, \( D \) is the dimension of the space and \( g \) is proportional to the interaction strength. The function \( \psi \) is so-called pseudopotential and is a function of time and location. Other adjacent sites (next nearest) can be considered in the Eq. 20 which leads to a more general form of the above equation [33]: \[ F(x) \equiv -c_0 \psi(x) g \nabla \psi(x) \] (21) In the Shan-Chen model the force at a given lattice point depends on all local neighbor’s characteristics. So the following can be written: \[ F_\phi(x) = -G \psi(x) \Sigma_i w_i \psi(x + e_i) e_i \] (22) where coefficient \( G \) controls the strength of the attraction. The function \( \psi \) is \( \psi = \psi(x) \), where \( \rho \) depends on time and location. \( c_i \) and \( w_i \) are respectively lattice velocity vector and its weight in selected lattice model. Therefore, force is introduced to account for attraction. The contributions of state and surface tension to the equation can be observed through Taylor expansion. Taylor expansion of the force can be written as [34]: \[ F_\phi((x)) = -G \psi(x) \left( \frac{1}{3} \partial_\phi \psi + \frac{1}{18} \partial_\phi \Delta \psi \right) + O(\phi^2) \] (23) The following formulation is derived algebraically [34]: \[ F_\phi((x)) = -G \psi(x) \left( \frac{1}{3} \partial_\phi \psi + \frac{1}{18} \partial_\phi \Delta \psi \right) \] \[ = -G \left( \frac{1}{6} \partial_\phi \psi^2 + \frac{1}{18} (\partial_\phi (\psi \Delta \psi) - \Delta \psi \partial_\phi \psi) \right) \] \[ = -G \left( \frac{1}{6} \partial_\phi \psi^2 + \frac{1}{18} (\partial_\phi (\psi \Delta \psi) + \frac{1}{2} \partial_\phi \nabla \psi^2 - \partial_\phi \partial_\phi \psi \partial_\psi \psi) \right) \] (24) The force influence can be included to in the momentum-flux tensor [34, 33]: \[ \partial_\phi P_{\phi \phi} = -F_\phi + \partial_\phi \rho \] (25) The equation of state for the LBE is \( \rho = c_s^2 \rho \) so: \[ \partial_\phi P_{\phi \phi} = -F_\phi + \partial_\phi \left( c_s^2 \rho \right) \] (26) Thus, the flux tensor \( P_{\phi \phi} \) is modified as follows: \[ P_{\phi \phi} = \left( c_s^2 \rho + \frac{G}{6} \psi^2 + \frac{G}{36} \nabla \psi^2 + \frac{G}{18} \psi \Delta \psi \right) \delta_{\phi \phi} - \frac{G}{18} \partial_\phi \psi \partial_\phi \psi \] (27) By analogy with classical mechanics, the potential of the force can be introduced as: \[ U = \frac{G}{6} \psi^2 + \frac{G}{36} \nabla \psi^2 + \frac{G}{18} \psi \Delta \psi \] (28) Since the gradient terms in Eq. 28 are in small compared to the leading terms (the characteristic length of the interface is longer than the lattice spacing, as in all diffuse-interface methods), the Eq. 28 can be approximated: \[ \rho = \rho c_s^2 + \frac{G}{6} \psi^2 \] (29) By a suitable choice of the pseudo-potential \( \psi(x) \), this equation can describe the separation of phases. One simple and usual choice can be \( \psi = \rho \). By using this pseudo-potential function, the momentum flux tensor resembles diffuse interface method. However, the choice of \( \psi = \rho(x, t) \) is not the best in terms of stability. When \( \psi \) equals \( \rho \), it becomes larger for larger \( \rho \). Thus, the attractive potential contains a malfunctioning loop: the larger density \( \rho \) leads to a larger \( \psi \) which causes larger gradients and instabilities. \( \psi \) is \( \rho \) good for small gas-liquid density ratios. In the case of aluminum liquid and hydrogen gas (two-phase system), density ratio is considerably higher. Therefore, to handle the pseudopotential function $\psi$ for larger $\rho$ while preserving its ratio for smaller $\rho$, the following choice of the pseudopotential is used: $$\psi(\rho) = 1 - \exp(-\rho)$$ Which is for small $\rho$ equals to $\psi(x) = \rho$ (Fig.1) and for large densities, $\psi(x) = 1$ (Fig.2). This choice of the pseudopotential allows separation of gas and liquid in larger density ratios (if not more than 60-70) [35]. $$p_0 = \frac{\rho}{3} + \frac{G}{6} (1 - \exp(-\rho))$$ And from Eq. 31 and Eq. 32 one would get: $$\frac{1}{3} + \frac{G_{critical}}{3} \exp(-\rho_{critical})(1 - \exp(-\rho_{critical})) = 0$$ Solving these equations lead to $G_{critical} = -4$ and $\rho_{critical} = \ln(2)$. This means that if the system is initialized with the liquid density more than $\ln(2)$ and the gas density less than $\ln(2)$ in simulations with $G \leq -4$, the result is stable and separation will occur. 2.1.3. Bubble nucleation and growth Number of bubble nucleation sites depends on the initial amount and size of the blowing agents. This number which is based on experimental results, is initially inserted into the main procedure. A time random subroutine is used to determine nucleation site positions in a 2D domain. These locations called domain gas points are in fact virtual blowing agents which in lattice domain are defined as gas nuclei and hydrogen density resulting from decomposition of the blowing agents, is accordingly calculated for these points. Other lattice points are set as liquid and give aluminum density. After this step, all numbers and parameter are changed to dimensionless parameters by open source OpenLB code [37]. Hydrogen gas release rate is calculated in each time step and added to each lattice point by pressure increment. $$\frac{dp}{dt} = A \times \frac{dn}{dt} \frac{N}{N}$$ where $\frac{dp}{dt}$ is pressure increase rate for each lattice point that refers to gas, $A$ is a constant which depends on gas behavior (in case of ideal gas $A = \frac{RT}{V}$ where $R$ is gas constant, $T$ temperature and $V$ is volume), $\frac{dn}{dt}$ is gas release rate in mole sec and $N$ is population of lattice gas points. Thus, because of pressure increase, pressure expansion is defined by multiphase code that has been developed in this work. 2.1.4. Program algorithm The flowchart of the main program algorithm is shown in Fig. 3. Present code has been developed base on OpenLB open source code. The Shan-Chen model was incorporated and some modifications were added to the core structure of this algorithm. In Fig. 3, the red boxes are the codes developed by open source community and the green boxes demonstrate the developed or modified parts, which where achieved in this study. 2.1.5. Bubbles interaction and modification of Shan-Chen model Interaction of bubbles in pure liquid, without suspended solid, modeling techniques is completely different from liquids containing floating particles (e.g. SiC particles in molten aluminum). In case of two moving bubbles in pure aqueous liquid, if they are closed to each other, common behavior is increment in their surface curvature, that leads to merging and coalescence phenomena from the contact tip (See Fig. 4). However, as shown in Fig. 5 for molten metals, due to existence of a lot of solid particles (impurities and inclusions), interaction between bubbles have a different behavior. Experimental observations during aluminum foam production show a particles network see Fig. 5 between bubbles, which is often called oxide network [7]. This network at interface act as a mechanical barrier and prevent further cell wall thinning. Therefore, main mechanism of foam stabilization between bubbles is due to particle confinement (See Fig. 5). To cover this phenomenon, some simple conditions are defined. First of all, it is assumed that each bubble interacts with liquid domain only, i.e. any numerical or logical conflicts between the bubbles are neglected. Secondly, each bubble possesses an interaction zone in the liquid phase as a result of its dynamic and velocity vectors. When these domains reach each other, the attracting force between the bubbles begins its performance. As mentioned earlier, a barrier of oxide-networks is formed between these domains that prevents bubbles’ coalescence. This effect could be modeled as an imaginary pressure in thin walls. By a simple condition the oxide-network effect can be simulated in the LBM code. This condition states in order to calculate corresponding Shan-Chen force at each lattice point when the interaction zones of bubbles collide, one would use the nearest bubble to that point and the effects of the rest of near bubbles are ignored, because their effect is practically neu- eralized by the oxide-network. This statement yields acceptable results in the final simulation. The modified Shan-Chen algorithm is represented in Fig. 6. The computational procedure is conducted by two separate lattices, one for the melt and the other for the gas. This separation requires the utilization of the pseudopotential function, described in Eq. 30 and at the end of each time step, the lattices are coupled. Velocity and density at each lattice point is computed by Eq. 11. Next step is the detection of the lattice points having the material between the melt and the gas (according to their velocity and density) and computing a new velocity for these points: $$\mathbf{u}_{\text{total}} = \frac{\mathbf{u}_{\text{melt}} + \mathbf{u}_{\text{gas}}}{\sum \rho}$$ \hspace{1cm} (36) Now the interaction potential could be calculated at each lattice point of the phases: $$\xi = \rho c^2 + \frac{G}{6} \psi^2$$ \hspace{1cm} (37) The final stage is to compute the velocities according to the calculated interaction potential and the external forces. But in the modified model, a correction is applied on the computed values. New lattices are created for each bubble, and contribution of each lattice (i.e. each bubble) to the velocity of the desired point in liquid lattice is computed: $$\xi_{\text{gas}} = \begin{cases} 0 & \text{if} \sum_{k=1}^{n} |\xi_k| = 0 \\ \text{Max} (\xi_1, \ldots, \xi_n) & \text{if} \sum_{k=1}^{n} |\xi_k| = 1 \\ \text{Min} (\xi_1, \ldots, \xi_n) & \text{if} \sum_{k=1}^{n} |\xi_k| \neq 1 \end{cases}$$ \hspace{1cm} (38) where $n$ is the number of bubbles in the domain. And the final velocities could be calculated: $$\mathbf{u}_{\text{gas}} = \mathbf{u}_{\text{total}} + \tau_{\text{gas}} (F_{\text{gas}} - G\xi_{\text{melt}})$$ \hspace{1cm} (39) $$\mathbf{u}_{\text{melt}} = \mathbf{u}_{\text{total}} + \tau_{\text{melt}} (F_{\text{melt}} - G\xi_{\text{gas}})$$ \hspace{1cm} (40) When the interaction condition is applied to simulate the oxide network, the bubbles would never cross the oxide network barrier and no coalescence occurs in the main domain. To solve this problem, another condition should be defined. If this condition is defined based on experimental data, it would dictate if the distance between two bubbles reach a critical number, the oxide network wall condition would be removed, which leads the normal procedure of bubble dynamics to proceed. In mathematical and computational declarations, various variables could be processed in each time step in order to determine when to remove the wall condition. In this study, the pressure field and its second derivative in normal direction are the chosen criteria to develop a condition to model removal of thin film and bubble coalescence. This condition is removing the wall when the second derivative of pressure equals zero: $$\eta_n = \begin{cases} 1 & \frac{d^2 p}{dh^2} \neq 0 \\ 0 & \frac{d^2 p}{dh^2} = 0 \end{cases}$$ \hspace{1cm} (41) By this removal of interaction condition, bubbles rapidly merge and their dynamic effect on liquid domain could be observed. 3. Experimental model 3.1. Foam formation dynamics Metal foams consist of bubbles solidified just before the coalescence stage. Bubble coalescence is an important step in foam formation process, in which the bubbles are merged by two different mechanisms. The first mechanism is the diffusion of gas from small bubbles to the bigger ones, known as Oswald Ripening, and is more understandable. The second mechanism is thin wall rupture. A thin film is formed between the bubbles while approaching each other. The characteristic of this thin film is the same as the continuous phase; for example, in aqueous solutions, the interaction of surfactants in bubble surface is the reason of the existence of this film [14]. The behavior of bubbles depends on the low-range and high-range forces which are the result of the type of surfactant, temperature and other components in the solution. In aqueous solutions, this mechanism depends primarily on the type of surfactant and it has little dependence on the characteristic of the phases. However, in some cases, such as air bubbles in oil, where the van-der Waals forces have low contribution in the interaction, the mechanism is different. In these solutions, the surfactants would be replaced by stabilizers. Presence of suspended impurity particles could result in a delay in coalescence stage [14]. Thin film rupture phenomena would be described in two different mechanisms. One of these mechanisms is the nucleation of a void and its growth due to surface tension forces. In this theory, in micro scale, a hole is formed randomly in the thin film. This formation consumes the energy $E_p = 2\pi r^2$. If the size of the void exceeds the critical radius $r^* = (\frac{E_p}{\gamma})$, stability is expected for the formed void, but in sizes less than the critical value, the void would be removed. Thus this mechanism requires activation energy $E_a = E(r^*)$ to start, i.e. the nucleation of void is a thermal activated mechanism and would be described by Arrhenius equation [14]. The second mechanism, which is one of the considerations in present study, considers an instability similar to Spinodal decomposition. In this mechanism, if the thickness of the thin film falls below a critical value due to drainage, a perturbation will occur. Now the instability in the thin film is appeared as the wavelength of this vibration, exceeding the critical wavelength, which leads to the rupture of the film. This critical wavelength would be calculated as below: $$\lambda_c = \sqrt{\frac{2\pi^2 \gamma}{d^2 V/dh^2}}$$ \hspace{1cm} (42) where $\gamma$ is the surface energy and $V(h)$ the free energy of interface as a function of the thickness. If one considers the thin Input DATA from Main Program Create temporary matrices of density and velocity for fluid and gas Compute density and velocity on every cell for fluid and gas Compute the common velocities shared among fluid and gas phases Compute the interaction potential of each cell on both phases Neglect bubbles direct interaction on each other If any intersected Affected zone Yes Locate oxide network barrier wall in interaction area on equal velocity cells of each bubble interact domain No Neglect effect from other side of barrier wall Compute the final velocities due to the interaction potential and external forces Output DATA to Main Program Finish Figure 6: Modified Shan-Chen Algorithm (Green: User Codes, Red: Open Source Codes) film as a cylinder with radius $R_f$ and thickness $h$ which is enclosed by two interface with surface tension $\gamma$, then the critical thickness of drainage would be: $$h_c = 0.22\sqrt{\frac{A R_f^2}{\gamma}}$$ (43) As the thin film thickness reaches this value, the rupture will occur. The time taken from the instability to the rupture could be calculated too: $$\tau = \frac{96\pi^2 \gamma h^5}{A^2}$$ (44) If the limitation could be neglected, the thickening would continue up to the formation of a molecular wall. But in the presence of stabilizer particles, surfactants or oxide films, there would be a different situation. The described mechanism is more suitable for rapid growth, in which the system has no surfactant. Consequently, this mechanism is appropriate to be used in present investigation. In metal melts, the oxide films and stabilizer particles are presented, which means it’s more probable for the second mechanism to occur. Thus one of the objectives of developed code is to model the instability in the thin wall formed between the bubbles. ### 3.2. Foam production To study the structure of a porous metal foam, Formgrip method is chosen to produce aluminum metal foam. This method is a combination of powder metallurgy and melting method. At first, precursor of A356 with TiH$_2$ is produced by melting. Then the precursor containing bubble nuclei is placed in a mold and is heated in furnace. Near the liquidus temperature, the precursor suddenly begins to blow. Bubble growing continues until they reach each other and before coarsening stage, the part is solidified. Then it is prepared for metallography images from cross-section of A356 foam after etching process. Finally, the experimental metallography images will be compared with bubbles images obtained from a simulation code that is developed in the present study. Also accuracy of the present code is evaluated as quantitative. For producing the precursor, around 350g aluminum 356 alloy is melted in the furnace, around 1.5 %wt. blowing agent is mixed with aluminum powder with fraction of 0.5. For improving blowing agent wetting property in aluminum alloy melt and better uniform distribution, at 700 °C the blowing agent mixture is added to the melt. In the next step, the furnace temperature is set to 600 °C. When the temperature reaches 620 °C, the mixer rpm is set to 1500 and stirs for 1-2 min. In this step, more stirring causes more gas release. The resulting melt is rapidly casted into a metal mold. The produced solid is called precursor. The precursor is cut for foaming process according to the mold size (a cylinder with a radius of 40mm and 80mm height). Then the mold and the precursor are heated in furnace to blow. In the present study, the effect of blowing temperature on the stability of foam for 675, 725 and 775 °C is investigated. For each temperature, 2-3 samples are produced to estimate the optimized foam processing time for producing foam with minimum density and stable cell structure. Schematic of foam producing steps is shown in Fig. 7. #### 3.3. Experimental test and validation In order to determine the accuracy of the simulation results, simulated cellular structure of the present code have been compared with the experimental results. Thus, following the production of A356 foam, samples were sliced and mounted by black epoxy resin. For this purpose, the samples were washed with alcohol, then heated up by a dryer for better resin penetration in the foam cells, and are finally mounted. After curing, the samples’ surfaces are polished with 230 to 800 grit sandpapers. Samples’ surfaces need to be polished in order to give a clear picture of cellular structures. Images of samples cross sections are taken by SONY digital camera with 300dpi resolution. ### 4. Results The coarsening of two in line bubbles shown in Fig. 8 without gravity have been simulated by two different methods. Fig. 9 shows the results of the interaction between two bubbles simulated by COMSOL commercial software using finite element method and level-set model. Results of LB method with OpenLB open source code is shown in Fig. 10. Multiphase model is Shan-Chen and lattice is D2Q9. Simulation conditions can be seen in Table 1. In present study, modified Shan-Chen model in LB method is used to simulate the behavior of two in line bubbles in a foam like situation. Simulation conditions are listed in Table 2 and results are shown in Fig. 11. In Fig. 12, the result of the pressure and velocity fields is demonstrated by the plot of the values across a vertical line, before and after the instability caused by the perturbation field of the interacting bubbles. The Simulation results of bubble growth in a small domain of closed-cell aluminum foam structure with 6 primary bubbles in the mirror boundary conditions are shown in Fig. 13 and the simulation data are listed in Table 3. In Fig. 14 magnified picture of aluminum foam cellular structure is shown to evaluate the accuracy of this study’s code in regards to the detection of cell wall thinning stage in bubble coarsening (see top right of Fig. 14). Small domain of Fig. 14, as mentioned before is simulated by mirror boundary condition which dictates that if any melt comes out of a wall it has to come from an opposite one. Thus, by repeating the simulated mirror domain, domain of a few millimeters can be transformed, by a good approximation, to a few centimeters domain. The result of such repetitions is shown in Fig. 15. Blue and red color of phase contours have been changed to gray scale to resemble the color of aluminum foam cross sections. In this case, it could be assumed that the speed of solidification is fast enough to freeze the molten aluminum foam into solid state as the cell structure maintains its molten state. Thus Fig. 15 can be a part of a solid aluminum foam structure. In other words, Fig. 15 can be considered as a simulation metallography picture of porous Table 1: Simulation condition for two in line bubbles <table> <thead> <tr> <th></th> <th>COMSOL</th> <th>OpenLB</th> </tr> </thead> <tbody> <tr> <td>Domain dimension (mm)</td> <td>20 × 30</td> <td>20 × 30</td> </tr> <tr> <td>Fluid density (g/cm³)</td> <td>2.7</td> <td>2.7</td> </tr> <tr> <td>Gas density (g/cm³)</td> <td>0.089</td> <td>0.089</td> </tr> <tr> <td>Initial condition</td> <td></td> <td></td> </tr> <tr> <td>Melt</td> <td>V = 0 mm/s</td> <td>V = 0 mm/s</td> </tr> <tr> <td></td> <td>P = 1 atm</td> <td>P = 1 atm</td> </tr> <tr> <td></td> <td>µ = 1.10 × 10⁻³ N.s/m²</td> <td>µ = 1.10 × 10⁻³ N.s/m²</td> </tr> <tr> <td>Bubble</td> <td>V = 3 mm/s</td> <td>V = 3 mm/s</td> </tr> <tr> <td></td> <td>P = 1 atm</td> <td>P = 1 atm</td> </tr> <tr> <td></td> <td>µ = 1.87 × 10⁻⁵ N.s/m²</td> <td>µ = 1.87 × 10⁻⁵ N.s/m²</td> </tr> <tr> <td>Boundary condition</td> <td>Slip</td> <td>Mirror</td> </tr> <tr> <td>Initial bubbles D (mm)</td> <td>8</td> <td>8</td> </tr> <tr> <td>Final bubbles D (mm)</td> <td>11.29</td> <td>11.30</td> </tr> </tbody> </table> Figure 8: Initial state of the validation simulation, two gas bubble in aluminum melt Table 2: Simulation condition for two inline bubbles by LB method and modified Shan-Chen model <table> <thead> <tr> <th></th> <th>OpenLB</th> </tr> </thead> <tbody> <tr> <td>Domain dimension (mm)</td> <td>45 × 45</td> </tr> <tr> <td>Fluid density (g/cm³)</td> <td>2.7</td> </tr> <tr> <td>Gas density (g/cm³)</td> <td>0.089</td> </tr> <tr> <td>Initial condition</td> <td></td> </tr> <tr> <td>Melt</td> <td>V = 0 mm/s</td> </tr> <tr> <td></td> <td>P = 1 atm</td> </tr> <tr> <td></td> <td>µ = 1.10 × 10⁻³ N.s/m²</td> </tr> <tr> <td>Bubble</td> <td>V = 3 mm/s</td> </tr> <tr> <td></td> <td>P = 1 atm</td> </tr> <tr> <td></td> <td>µ = 1.87 × 10⁻⁵ N.s/m²</td> </tr> <tr> <td>Boundary condition</td> <td>Mirror</td> </tr> <tr> <td>Initial bubbles D (mm)</td> <td>8</td> </tr> <tr> <td>Final bubbles D (mm)</td> <td>11.30</td> </tr> </tbody> </table> aluminum foam structure. Fig. 16 shows the experimental metallography pictures of aluminum A356 foam that produced by Formgrip method in 675, 725 and 775 °C, for comparison with the simulated metallographic pictures. The results of this comparison are shown in Fig. 17 and 18. 5. Discussion In Lattice Boltzmann method, the macroscopic properties of the domain of interest could be predicted by solving the LB equations at mesoscopic scale. In this investigation, this numerical method is used and the Shan-Chen scheme for multiphase modeling is modified to present a code to predict the behavior of metal foams. In available commercial CFD codes, the modeled behavior of bubbles is not similar to the dynamics seen in experimental observation. By modifying the Shan-Chen model (which is one the most accurate models in multiphase LB simulations), improved results in field of bubble dynamics would be achieved. In order to validate and compare the developed code, two bubbles at growth stage in a container are considered and the dynamics of interaction is determined by using a conventional CFD code, unmodified LB code and present code. The boundaries of the domain are assumed to be closed for the gas phase and opened for the liquid phase, which causes the extra liquid exit the domain as the gas bubbles grow. The interaction begins as the volume of the bubbles increases. The initial state of this model is represented in Fig. 8. According to Fig. 9 and Fig. 10, obtained simulation results from the LBM method with unmodified Shan-Chen model by OpenLB code, and the FEM with level set model by COMSOL software have a same behavior during interaction of two bubbles. In both methods, as the bubbles collide, a tip is formed on bubbles boundary at the interface zone between two bubbles. This shows the absorption force of bubbles that moves bubbles toward each other for merging and decreasing surface energy. Obtained quantitative results from both simulations listed in Table. 4. These results are factual for every liquid without any solid impurity. But as mentioned before this behavior is not acceptable for metals melt, especially in aluminum and aluminum alloys foaming process. In metals there is no tip at the intersection of two bubbles. Therefore, for bubbles growth in metal melt, a new model should be developed. In this study, this objective is accomplished by using a modified version of the Shan-Chen model in LBM simulation of metal foaming process. The result of the simulation performed using this new code for aluminum melt compared with COMSOL and OpenLB software is shown in Table. 4. The result shown in Fig. 10 means that the bubble dynamics equations are well satisfied and the result shows behavior based on these equations. But the behavior of bubbles in the interaction is not the one expected from metal melts due to the presence of impurities and the particle-network as discussed before. In Fig. 11, simulation results illustrated based on the modified Shan-Chen model. As shown, in this figure, at interface of the bubble interaction, a thin film is formed and the merging phenomenon does not occur until a specific criterion is met. Furthermore, to complete the validation results of the developed code, the pressure and velocity values across a vertical line is shown in Fig. 12. It is observed that for a specific Figure 11: Coarsening simulation of two in line bubbles by LB method and modified Shan-Chen multiphase model in OpenLB Figure 12: Plot of pressure and velocity across a vertical line in the middle of two bubbles. Left: before instability, Right: after instability. Red line indicates the pressure and green line is vertical velocity. Figure 13: Simulation results of foaming stage for small domain of metal foam by LB method and modified Shan-Chen model with mirror boundary condition in OpenLB thickness an instability will occur, which is dependent on the size of the bubbles. This instability could be seen in the pressure profile (right image of Fig. 12). Thus, in the beginning of the instability, the second derivative of pressure ($\nabla^2 P$) profile in the lattice point would be zero, which indicates the initialization of bubbles wall rupture. Then it is possible and more comfortable to determine the wall rupture by using the pressure profile and pressure second derivative instead of detecting the critical thickness. By applying this criterion to the domain of foam formation, the merge condition of the gas bubbles would be detected based on the second derivative of pressure field at each lattice points, which leads to an improved modeling of metal foam formation process. Designing an experiment that could show the dynamics of two moving bubbles in aluminum melt to validate present simulation is very expensive and requires very especial equipment for casting and would be impossible due to non-transparent molten metals. In Fig. 15 shows simulation results of a cross-section of A356 foam based on the modified Shan-Chen method at present code. In this image, a small portion of the domain has been repeated by using periodic boundary condition. Fig. 13 shows foaming stage for small domain of metal foam by time. Bubbles with random distribution began to grow after nucleation. Bigger bubbles have a higher growth rate than the others. Each bubble has an affected zone, and when these zones reach each other, bubbles interaction will begin. Simulation of bubbles’ growth will continue until first cell reaches the wall rupture criterion as like Fig. 14. After this time (best foaming time), foaming simulation process would suddenly enter the aging step and bubbles coalescence, which leads to a severe drainage in metal foam structure. These simulation metallography images could be used for predicting of experimental metallography images (as like Fig. 16) and optimum foaming time. These comparisons are represented in Fig. 17 for 675 °C and Fig. 18 for 725 and 775 °C, respectively. In addition to visual results, quantitative results are extracted from Fig. 17 simulation data in order to validate. These extracted results are processed by using MATLAB image processor and are illustrated in Fig. 19 and Table. 5. These data show a minor error between the simulation and the experiment results. Therefore, present code based on modified Shan-Chen model and LB method could simulate and predict foamy structures for aluminum A356 foams during isothermal foaming process. ### 6. Conclusions In this investigation, the Lattice Boltzmann Method (LBM) was utilized for understanding of foaming process by simulation of different stages of the Aluminum A356 foam production process at micro and meso scales. Therefore, to predict the structure of metal foam during foaming process, a model is established to simulate the dynamics of bubbles interaction based on development of Shan-Chen model. The presented model can consider the effect of the attraction-repulsion barriers among bubbles into the A356 aluminum foam liquid due to the solid particles network. In order to validate the presented model, results were compared by both some other reference codes and experimental data. Comparison of cellular structure obtained from the experimental route (experimental metallography) and the numerical code (simulation metallography) shows a good consistency. The presented code is also capable of simulating and presenting virtual metallography images for all aluminum alloys foams. Therefore, this software can be used for controlling and predicting density of foams combined with uniform distribution of bubbles at the metal foams. <table> <thead> <tr> <th></th> <th>Simulation</th> <th>Experimental</th> <th>Error</th> </tr> </thead> <tbody> <tr> <td>Bubble percentage</td> <td>44.3%</td> <td>45.5%</td> <td>2.64%</td> </tr> <tr> <td>Foam Density ($\frac{\text{g}}{\text{cm}^3}$)</td> <td>1.50</td> <td>1.47</td> <td>2.04%</td> </tr> <tr> <td>Mean bubble size (mm)</td> <td>3.03</td> <td>3.05</td> <td>0.66%</td> </tr> </tbody> </table> **Table 5: Comparison of extracted data from simulation and experimental metallographic cellular structures of Fig. 17** Figure 16: Metallographic image of aluminum A356 metal foam Figure 17: Experimental and simulation metallographic structure of aluminum metal foam produced by formgrip in 675 °C Figure 18: Experimental and simulation metallographic structure of aluminum A356 foam (left: 725 °C and right: 775 °C) Figure 19: Bubble size distribution of simulation and experimental samples of Fig. 17 References
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Deletion of Atbf1/Zfhx3 In Mouse Prostate Causes Neoplastic Lesions, Likely by Attenuation of Membrane and Secretory Proteins and Multiple Signaling Pathways Xiaodong Sun, Emory University Xiaoying Fu, Emory University Jie Li, Emory University Changsheng Xing, Emory University Henry F. Frierson, University of Virginia Health System Hao Wu, Emory University Xiaokun Ding, Emory University Tongzhong Ju, Emory University Richard Cummings, Emory University Jin-Tang Dong, Emory University Journal Title: Neoplasia Volume: Volume 16, Number 5 Publisher: Elsevier | 2014-05-01, Pages 377-389 Type of Work: Article | Final Publisher PDF Publisher DOI: 10.1016/j.neo.2014.05.001 Permanent URL: https://pid.emory.edu/ark:/25593/mr457 Final published version: http://dx.doi.org/10.1016/j.neo.2014.05.001 Copyright information: © 2014 Published by Elsevier Inc. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported License (http://creativecommons.org/licenses/by-nc-nd/3.0/), which permits distribution, public display, and publicly performance, making multiple copies, provided the original work is properly cited. This license requires credit be given to copyright holder and/or author, copyright and license notices be kept intact. This license prohibits exercising rights for commercial purposes. Accessed December 15, 2019 6:24 AM EST Deletion of Atbf1/Zfhx3 In Mouse Prostate Causes Neoplastic Lesions, Likely by Attenuation of Membrane and Secretory Proteins and Multiple Signaling Pathways Xiaodong Sun*, Xiaoying Fu*,†, Jie Li*, Changsheng Xing*, Henry F. Frierson‡, Hao Wu§, Xiaokun Ding¶, Tongzhong Ju¶, Richard D. Cummings§ and Jin-Tang Dong* *Department of Hematology and Medical Oncology, Emory University School of Medicine, Winship Cancer Institute, Atlanta, GA 30322; †Department of Pathology, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; ‡Department of Pathology, University of Virginia Health System, Charlottesville, VA; §Department of Biostatistics and Bioinformatics, Emory University, Atlanta, GA 30322; ¶Department of Biochemistry, Emory University, Atlanta, GA 30322 Abstract The ATBF1/ZFHX3 gene at 16q22 is the second most frequently mutated gene in human prostate cancer and has reduced expression or mislocalization in several types of human tumors. Nonetheless, the hypothesis that ATBF1 has a tumor suppressor function in prostate cancer has not been tested. In this study, we examined the role of ATBF1 in prostatic carcinogenesis by specifically deleting Atbf1 in mouse prostatic epithelial cells. We also examined the effect of Atbf1 deletion on gene expression and signaling pathways in mouse prostates. Histopathologic analyses showed that Atbf1 deficiency caused hyperplasia and mouse prostatic intraepithelial neoplasia (mPIN) primarily in the dorsal prostate but also in other lobes. Hemizygous deletion of Atbf1 also increased the development of hyperplasia and mPIN, indicating a haploinsufficiency of Atbf1. The mPIN lesions expressed luminal cell markers and harbored molecular changes similar to those in human PIN and prostate cancer, including weaker expression of basal cell marker cytokeratin 5 (Ck5), cell adhesion protein E-cadherin, and the smooth muscle layer marker Smα; elevated expression of the oncoproteins phospho-Erk1/2, phospho-Akt and Muc1; and aberrant protein glycosylation. Gene expression profiling revealed a large number of genes that were dysregulated by Atbf1 deletion, particularly those that encode for secretory and membrane proteins. The four signaling networks that were most affected by Atbf1 deletion included those centered on Erk1/2 and IGF1, Akt and FSH, NF-κB and progesterone and β-estradiol. These findings provide in vivo evidence that ATBF1 is a tumor suppressor in the prostate, suggest that loss of Atbf1 contributes to tumorigenesis by dysregulating membrane and secretory proteins and multiple signaling pathways, and provide a new animal model for prostate cancer. Neoplasia (2014) 16, 377–389 Introduction The AT-motif binding factor 1/zinc finger homeobox 3 (ATBF1/ZFHX3) gene encodes a large protein structurally characterized by multiple zinc-finger motifs and four homeodomains [1]. ATBF1 appears to play a role in neuronal differentiation and cell death [2–4], atrial fibrillation [5,6], and embryonic development [7]. ATBF1 could be a tumor suppressor in several organs including the prostate. breast, stomach, liver, and head and neck. Chromosomal deletion frequently occurs in cancer cells, which can inactivate tumor suppressor genes (TSGs) and thus contribute to tumorigenesis [8]. Our previous characterization of 16q22 deletion and mutational screening identified ATBF1 as a candidate TSG as it has frequent deletion and somatic mutations in prostate cancer [9]. Recent genome-wide sequencing of castration-resistant prostate cancer indicated that ATBF1 is the second most frequently mutated gene in human prostate cancer [10]. ATBF1 mutation is also frequent in endometrial cancers [11] and the ATBF1 locus is frequently deleted in breast cancers [12]. A germline variant of ATBF1 is linked to increased risk of sporadic prostate cancer [13] and ATBF1 expression is significantly reduced in breast cancer [12,14], hepatocellular carcinoma [15], gastric cancer [16,17], and two transgenic mouse models of prostate cancer, TRAMP-ARpTR77/AY and ARR, PB-c-myc [18,19]. Reduced expression and/or mislocalization of ATBF1 protein has been detected in several types of cancer [14,20,21]. These alterations are associated with worse patient survival in breast cancer and histopathologic progression in head and neck cancer [14,21]. While these studies suggest a tumor suppressor function for ATBF1 in human cancer, this hypothesis has not been tested in animal models. How ATBF1 might suppress carcinogenesis has not been determined, although as a transcription factor ATBF1 has been shown to regulate the expression of several differentiation or tumor-related genes including AIP, aminopeptidase N, neurod1, MUC5AC and p21WAF1 [4,22–25]. Few mouse models are truly relevant to human prostate cancer by neoplastic phenotypes and/or genetic causes [26] but models still provide a powerful platform for understanding prostate cancer biology and developing novel therapies against prostate cancer. In this study, we examined ATBF1 function in a knockout mouse model. Using the Cre-loxP system, we deleted Atbf1 specifically in mouse prostatic epithelium (PE) and found that inactivation of Atbf1 caused hyperplasia and mouse prostatic intraepithelial neoplasia (mPIN), primarily in the dorsal prostate (DP). A number of molecular alterations resembling those in human prostate cancer were detected in Atbf1 deletion-induced prostatic lesions. Furthermore, Atbf1 deletion dysregulated the expression of a large number of genes involved in multiple signaling pathways, particularly those that encode for secretory proteins and membrane proteins. Methods and Materials Ethics Statement All animal work was performed in compliance with relevant regulatory standards and was approved by the Institutional Animal Care and Use Committee of Emory University. Mouse Experiments The PB-Cre line transgenic mouse line was obtained from the NCI Mouse Models of Human Cancers Consortium (MMHCC, Frederick, MD, Cat#: 01XF5). Floxed Atbf1 mice (Atbf1lox/lox) in which the Atbf1 genomic DNA from exon 7 to exon 8 was flanked with loxP sequences, were generated in our previous study [7] and maintained on a mixed background of C57BL/6 J and 129SvJ. Atbf1lox/lox;PB-Cre+ (Atbf1fl/+) male mice were made by first crossing PB-Cre+ male mice with Atbf1lox/lox female mice, then crossing Atbf1lox/lox;PB-Cre+ male mice with Atbf1lox/lox female mice to obtain mice with all the desired genotypes. Atbf1lox/lox;PB-Cre+ (Atbf1fl/+) male mice were examined as controls for different groups at different ages. Six Atbf1lox/lox;PB-Cre+ male mice were also used as controls. All mice were genotyped by PCR using genomic DNA isolated from tail biopsies [7], Alleles of Atbf1lox (1248 bp), Atbf1wt (1071 bp) and Atbf1fl/fl (289 bp) were distinguished based on the size of their PCR products using primers 5′-GGCCCTTGACTGCATTCTTTTCTCTG-3′ and 5′-ATTCGTTAATGGAAGGTTCAGA-3′. Primers used for genotyping the Cre gene were 5′-CTGAAGATGGGACAGG CATTG-3′ and 5′-CATACTCGTTGCCAGACC-3′ (939 bp). Histological Analysis, Immunohistochemical (IHC) Staining, Immunofluorescence (IF) Staining, and Special Staining Prostatic tissues were surgically harvested and fixed in 4% formaldehyde overnight. Prostatic lobes were then dissected, embedded in paraffin, and sectioned at 5-μm thickness. Standard hematoxylin and eosin (H&E) staining was performed for histological analyses. Pathological diagnosis was performed by Dr. Henry F. Frierson and confirmed by Dr. Robert D. Cardiff via a paid service at the Center for Comparative Medicine, Department of Pathology, University of California at Davis. Previously established criteria for mouse prostatic lesions were followed [27,28]. For IHC staining, tissue sections were deparaffinized, rehydrated, and washed in PBS. Antigen retrieval was done by heating slides in a microwave oven for 15 min or in a pressure cooker for 3 min in citrated buffer (pH 6.0, 10 mM trisodium citrate). After blocking with 5% normal goat serum in Tris-buffered saline with 0.1% Tween-20 (TBST), tissue sections were incubated with primary antibodies at 4°C overnight, followed by incubation with EnVision Polymer-HPR secondary antibodies (Dako, Glostrup, Denmark) at room temperature for 40 min. After the application of DAB-chromogen, tissue sections were mounted and visualized under microscopes. Representative slides were scanned with NanoZoomer 2.0HT (Hamamatsu, Bridgewater, NJ), and pictures were captured using NDD.view software (Hamamatsu). Primary antibodies used in this study included anti-Ki67 (Lab Vision, Fremont, CA), anti-cytokeratin 5 (Covance, Princeton, NJ), anti-cytokeratin18 (Abcam, Cambridge, MA), anti-Ar, anti-Sma (Sigma-Aldrich, St. Louis, MO), anti-synaptophysin (Invitrogen, Carlsbad, CA), anti-Cdh1, anti-phospho-Erk1/2, anti-phospho-Akt, and anti-Spink3 (Cell Signaling Technology, Billerica, MA), anti-Muc1 (Thermo Scientific, Waltham, MA), and anti-clusterin (Santa Cruz Biotechnology, Dallas, TX). For immunofluorescent staining, tissue slides were prepared and incubated with primary antibodies as described above. Appropriate Alexa Fluor fluorochrome-conjugated secondary antibodies (Invitrogen) were used, and nuclei were counterstained with 4',6-diamidino-2-phenylindole (DAPI) for 5 min. Slides were mounted and visualized under fluorescent microscopes (Zeiss, Thornwood, NY). Primary antibodies included anti-Atbf1, anti-Tn, and biotinylated-HPA [21,29]. Special staining, including Periodic acid-Schiff (PAS) and Alcian blue, was performed by the Emory University Department of Pathology. Proliferation Assay Tissue sections of mouse prostates were immunostained with the anti-Ki67 antibody to detect cells that expressed the Ki67 proliferation marker. Slides were then scanned with the NanoZoomer 2.0HT scanner for cell counting. For each individual mouse, the number of Ki67-positive epithelial cells and the number of total epithelial cells in the dorsal prostate (DP) were determined using the ImageJ program [30]. The percentage of Ki67-positive epithelial cells in a DP was then... calculated and plotted against the genotype. Student’s t-test was performed to evaluate the statistical significance for a difference between two genotypes. Gene Expression Profiling and Signaling Pathway Analysis Dorsal prostate (DP) tissue from 4 Atbf1^fl/fl;PB-Cre (Atbf1^PE+/-) and 4 Atbf1^+/+;PB-Cre (Atbf1^PE+/+) mice aged 13-15 months was used in the microarray analysis. After the whole prostate was surgically isolated, one piece of DP from each mouse was freshly isolated, weighed and snap frozen in liquid nitrogen, and the remaining prostatic lobes were collected for histological analyses. The microarray experiment was performed by Beckman Counter Inc (Indianapolis, IN). Briefly, total RNA was extracted from DP tissues, and the quantity and quality were determined by spectrophotometry and an Agilent Bioanalyzer (Agilent Technologies, Palo Alto, CA). Two hundred nanograms of total RNA was converted into labeled cRNA with nucleotides coupled to fluorescent dye Cy3 using the Low Input Quick Amp Kit (Agilent Technologies) following the manufacturer’s protocol. Cy3-labeled cRNA (600 ng) from each sample was hybridized to an Agilent Mouse Whole Genome 8x60k Microarray. The hybridized array was then washed and scanned, and data was extracted from the scanned image using Feature Extraction version 10.7 (Agilent Technologies). To remove array specific effects and ensure that signals from different arrays began at the same baseline, quantile normalization was conducted on each microarray. Two R packages, siggenes (based on Statistical Analysis of Microarrays t-test) and MAANOVA ([MicroArray ANalysis Of VAriance] [31], were used to detect differentially expressed genes. Both software packages use a variance shrinkage approach to improve detection accuracy by combining information from all genes when estimating gene level variance. The final reported p-values were from R/MAANOVA. Genes with an expression fold change of 2 or greater and false discovery rate (FDR) less than 0.02 were considered differentially expressed. We then performed pathway analysis using the Ingenuity Pathway Analysis (IPA) program (http://www.ingenuity.com) (Ingenuity Systems, Redwood City, CA) to identify signaling pathways and networks that were attenuated by Atbf1 deletion. Subcellular localization of the corresponding proteins was determined based on... the Genecards (http://www.genecards.org) and the Plasma Proteome (http://www.plasmaproteomedatabase.org) databases. **Results** **Atbf1 Deletion Leads to Mouse Prostatic Intraepithelial Neoplasia (mPIN) with Increased Cell Proliferation** Mice with a tissue specific deletion of Atbf1 in prostatic epithelial cells (Atbf1PE-/−) were generated by breeding floxed Atbf1 mice (Atbf1floxt/+) with PB-Cre transgenic mice (Figure 1A). Prostate-specific deletion of Atbf1 was confirmed by PCR-based genotyping. In 9-week-old Atbf1floxt/++;PB-Cre+ (Atbf1PE-/−) mice, a smaller PCR product indicating the allele with deletion (Atbf1ΔCΔB) was observed in all prostatic lobes (anterior, dorsal, lateral and ventral prostates) but not in other organs examined (Figure 1B). Immunofluorescent staining demonstrated that Atbf1 was predominantly expressed in the nuclei of a majority of Atbf1ΔCΔB prostatic epithelial cells, and Cre-mediated Atbf1 deletion dramatically decreased Atbf1 protein expression in the Atbf1ΔCΔB prostate (Figure 1C). Quantitative RT-PCR analysis with cDNA from the dorsal prostate (DP) at 12-15 weeks showed that hemizygous deletion of Atbf1 significantly reduced Atbf1 mRNA expression (P < 0.0001) (Figure 1D), indicating a haploinsufficiency of Atbf1. To determine the consequence of Atbf1 deletion in the prostate, we examined a cohort of mice with wildtype Atbf1 (Atbf1ΔCΔB+) or hemizygous deletion of Atbf1 (Atbf1ΔCΔB−) (0.48% and 0.35% of cells, respectively), they were significantly more frequent (1.73%) in Atbf1-null (Atbf1ΔCΔB−) DPs (Figure 3A). The increase in Ki67-positive cells in Atbf1ΔCΔB− mice indicates accelerated cell proliferation in hyperplasia and mPIN lesions caused by the Atbf1 deletion (P < or = 0.0001) (Figure 3A). **Atbf1 Deletion in Mouse Prostates Dysregulates a Number of Genes, Particularly those that Encode for Secretory and Cell Membrane Proteins** As a transcription factor, Atbf1 regulates the expression of many genes. To understand what genes are dysregulated by Atbf1 deletion, we conducted a microarray analysis using DPs from 8 mice at 13-15 months of age, 4 with wildtype Atbf1 (Atbf1ΔCΔB+/+) and 4 with homozygous deletion of Atbf1 (Atbf1ΔCΔB−/−). Histological analysis confirmed normal prostatic phenotypes in the Atbf1ΔCΔB−/+ mice and hyperplasia and mPIN lesions in the Atbf1ΔCΔB−/− DPs. In addition to DP, Atbf1 deletion also caused precancerous lesions in other lobes of the prostate (Figure 2B). At 9-15 months of age, most Atbf1ΔCΔB−/− mice developed hyperplasia or mPIN in the lateral prostate (LP) and anterior prostate (AP), while the ventral prostate (VP) was least affected (Table 1). In addition, mice without the Cre transgene (2 each of Atbf1ΔCΔB+, Atbf1floxt/− or Atbf1ΔCΔB−/−), which maintained the wildtype Atbf1, had no visible hyperplasia or dysplasia by age 12 months, indicating that Atbf1 deletion caused the histopathologic phenotypes in Atbf1ΔCΔB−/− mice. The majority of human prostate cancers (70%) arise in the peripheral zone and the most analogous part in mice is the DP and LP [32]. Therefore we focused on the DP for further characterization. We examined cell proliferation, which is a hallmark for both cancerous and precancerous lesions, in DP by IHC staining of the Ki67 proliferation marker. Whereas Ki67 positive cells were rare in DPs with wildtype Atbf1 (Atbf1ΔCΔB+) or hemizygous deletion of Atbf1 (Atbf1ΔCΔB−) (0.48% and 0.35% of cells, respectively), they were significantly more frequent (1.73%) in Atbf1-null (Atbf1ΔCΔB−) DPs (Figure 3A). The increase in Ki67-positive cells in Atbf1ΔCΔB− mice indicates accelerated cell proliferation in hyperplasia and mPIN lesions caused by the Atbf1 deletion (P < or = 0.0001) (Figure 3A). **Validation of Differentially Expressed Genes by Quantitative RT-PCR** To validate differentially expressed genes, quantitative RT-PCR was performed in samples from both the 8 DPs used in the microarray analysis and additional DPs, including 7 of Atbf1ΔCΔB−/+ and 10 of Atbf1ΔCΔB−/−, and 7 of Atbf1ΔCΔB−/+ mice. Briefly, DPs from mice aged at 12 to 15 months were harvested, and total RNAs were isolated using Trizol reagent (Invitrogen) following the manufacturer’s instructions. One μg of total RNA was used for cDNA synthesis using the iScript reverse transcription kit (Bio-Rad, Hercules, CA). Quantitative RT-PCR was performed with the SYBR Premix Ex Taq™ Kit (Clontech Laboratories, Mountain View, CA) and the ABI Prism 7500 Real-time PCR System (Applied Biosystems, Carlsbad, California). Relative fold changes were calculated using the 2-ΔΔCt method, with mouse β-actin mRNA as the internal control. For each gene, PCR primers were designed to generate PCR products spanning different exons to avoid possible interference from genomic DNA contamination. Primer sequences and PCR product sizes are shown in Table S1. Deletion of Atbf1 causes mPIN in mouse prostates Sun et al. **Table 1. Differences in Atbf1 deletion-induced phenotype among prostatic lobes at different ages.** <table> <thead> <tr> <th>Prostatic lobes</th> <th>Age (Months)</th> <th>Atbf1 alleles</th> <th>Mice with different phenotypes (n)</th> <th>Total (n)</th> </tr> </thead> <tbody> <tr> <td>Dorsal</td> <td>4-7</td> <td>+/-</td> <td>Normal 6</td> <td>Hyperplasia 3</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>1</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>8</td> </tr> <tr> <td></td> <td>9-15</td> <td>+/-</td> <td></td> <td>7</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>4</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>1</td> </tr> <tr> <td></td> <td>17-24</td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>7</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>11</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>4</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>11</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>1</td> </tr> <tr> <td>Lateral</td> <td>4-7</td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>7</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>10</td> </tr> <tr> <td></td> <td>9-15</td> <td>+/-</td> <td></td> <td>4</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>11</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>1</td> </tr> <tr> <td>Anterior</td> <td>4-7</td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>5</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>8</td> </tr> <tr> <td></td> <td>9-15</td> <td>+/-</td> <td></td> <td>20</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>16</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>8</td> </tr> <tr> <td></td> <td>17-24</td> <td>+/-</td> <td></td> <td>9</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>3</td> </tr> <tr> <td>Ventral</td> <td>4-7</td> <td>+/-</td> <td></td> <td>6</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>5</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>17</td> </tr> <tr> <td></td> <td>9-15</td> <td>+/-</td> <td></td> <td>22</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>21</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>12</td> </tr> <tr> <td></td> <td>17-24</td> <td>+/-</td> <td></td> <td>11</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>18</td> </tr> <tr> <td></td> <td></td> <td>+/-</td> <td></td> <td>3</td> </tr> </tbody> </table> Notes: mPIN, mouse prostatic intraepithelial neoplasia; + and – indicate the presence and absence of an Atbf1 allele respectively. in the Atbf1PE+/− mice. Probes were synthesized from total RNA and hybridized to an Agilent mouse whole genome 8x60k chip, which covers 39,430 Entrez genes and 16,251 lincRNAs. After quantile normalization, gene expression was analyzed by two R computer programs, siggenes and MAANOVA, and the two programs generated similar results with a correlation of 0.97. A supervised gene list was generated using R/MAANOVA. With a false discovery rate at 0.02 and a fold change of 2 or greater, a total of 445 probes were differentially expressed in Atbf1PE−/− DPs, representing 176 upregulated and 279 downregulated genes (some genes were represented by two or more probes on the microarray) (Table S2). To validate differential expression of the genes between normal prostates and mPIN, we performed quantitative RT-PCR on a total of 32 samples, including 11 for Atbf1PE−/−, 10 for Atbf1PE−/+ and 11 for Atbf1PE+/+ mice. Twenty-six of 30 up-regulated and 5 of 6 downregulated genes were confirmed with statistical significance (P < 0.05) (Figure 4A, B and Table S3). A number of these molecules have been associated with cancer development. We selected two up-regulated genes, Spink3 and Clu, and confirmed their elevated protein expression in Atbf1PE−/− DP by IHC (Figure 4C). Among the 30 validated genes, 7 (Mcm10, Gabra4, Gabrb1, Rgs2, Serpib11, Sgl3a2, and Col4a6) were also differentially expressed in Atbf1PE−/− mice compared to wildtype mice, further indicating the haploinsufficiency of Atbf1 in the regulation of a subset of its target genes (Figure 4A). Notably, a number of the dysregulated genes encode secretory proteins or cell membrane proteins. Among the 391 differentially expressed proteins, 64 (16.4%) were annotated as secretory proteins, including Chu, Timp4, Wnt4, Citra and Col4a6, and 101 (25.8%) were reportedly localized to the cytoplasmic membrane, including Trps6, Prb, Tacstd2, Slc12a8 and Pgc3 (Table S2). In addition, 117 of the 391 differentially expressed proteins (29.9%) have been detected in the plasma or serum, according to the Plasma Proteome database (Table S2). Membrane proteins play essential roles in different cellular processes, and their abnormal expression and modification often occur during cancer development. One family of such proteins are mucins, which have an aberrant and unique expression pattern in cancer cells and thus have been used as diagnostic markers as well as therapeutic targets [33, 34]. Mucin 1 (MUC1) is an O-glycosylated transmembrane glycoprotein which primarily hydrates, lubricates and protects the epithelial luminal surfaces of ducts [35]. Its core peptide is attached with a number of O-glycans in normal cells but the level of glycosylation is reduced in tumors, leading to the exposure of epitopes for immunodetection and cytoplasmic localization of MUC1 [35, 36]. Therefore, we examined Muc1 expression, and found that Muc1 was significantly upregulated in Atbf1 deletion neoplastic lesions (Figure 3B). The increase in Muc1 expression in the cytoplasm has been associated with alterations in its glycosylation [35], and the Tn antigen, a truncated mucin-type O-glycan, is often overexpressed in human malignancies including prostate cancer [37]. We examined the expression of Tn antigen by immunostaining of prostates with both Helix pomatia agglutinin (HPA), a snail lectin which recognizes Tn antigen of glycoproteins, and an anti-Tn monoclonal antibody. Strong staining for Tn antigen was detected in Atbf1PE−/− DP but not in Atbf1PE−/+ DP, indicating that Atbf1 deletion increased Tn antigen expression (Figure 3B). **Atbf1 Deletion Attenuates Multiple Signaling Pathways Including the Activation of Erk1/2 AKT Oncogenic Signaling** We then input genes differentially expressed between prostates with and without Atbf1 deletion, along with their expression levels, into the Ingenuity Pathway Analysis (IPA) program to identify functional networks and signaling pathways that are affected by Atbf1 deletion. Several were identified to have statistically significant P values, and multiple biological processes were affected, including cell differentiation, tissue development, cell death, cell movement, secretion of bodily fluid, cation transport, atrial fibrillation and blood pressure regulation (Table S4). All these functions are associated with signals mediated by extracellular and cell membrane molecules. The four networks with the smallest P values are shown in Figure 5, which included those centered ERK1/2 and IGF1 (Figure 5A), Akt and FSH (Figure 5B), NF-κB (Figure 5C) and progesterone and β-estradiol (Figure 5D). Although no canonical pathways were predicted with statistical significance, all four of these networks play a role in cancer development. ERK and AKT are frequently activated during carcinogenesis, so we examined whether they are activated by Atbf1 deletion. Using IHC staining, we found that phosphorylated Erk1/2 and Akt, which represent the activated Erk1/2 and Akt, were clearly detected in Atbf1-null DPs but were undetectable in DPs with wildtype Atbf1 (Figure 3B). Deletion Induces mPIN in Mouse Prostates While a tumor suppressor function of \textit{ATBF1} has been suggested by its frequent chromosomal deletion at 16q22 and somatic mutations in human cancers [8–10], the effect of \textit{Atbf1} inactivation on tumorigenesis has not been tested in a mouse model because conventional deletion of \textit{Atbf1} in mice is embryonic lethal and loss of even one allele of \textit{Atbf1} results in preweaning mortality and partial embryonic lethality [7]. In this study, we used the \textit{Cre-loxP} system to specifically delete \textit{Atbf1} in mouse prostates. \textbf{Discussion} \textit{Atbf1} Deletion Induces mPIN in Mouse Prostates While a tumor suppressor function of \textit{ATBF1} has been suggested by its frequent chromosomal deletion at 16q22 and somatic mutations in human cancers [8–10], the effect of \textit{Atbf1} inactivation on tumorigenesis has not been tested in a mouse model because conventional deletion of \textit{Atbf1} in mice is embryonic lethal and loss of even one allele of \textit{Atbf1} results in preweaning mortality and partial embryonic lethality [7]. In this study, we used the \textit{Cre-loxP} system to specifically delete \textit{Atbf1} in mouse prostates. \textbf{Figure 2. Development of mouse prostatic intraepithelial neoplasia (mPIN) in Atbf1\textsuperscript{PE-/-} prostates.} (A) Representative hematoxylin and eosin (HE)-stained mouse tissue sections from dorsal prostates (DPs) with wildtype (Atbf1\textsuperscript{PE+/+}) (a-d) and null Atbf1 (Atbf1\textsuperscript{PE-/-}) (e-h) at 3, 6, 12 and 24 months. Images in i-l are magnified areas of the marked rectangles in images e-h respectively. Note that DPs with Atbf1 deletion (Atbf1\textsuperscript{PE-/-}) show normal prostate (e & i), hyperplasia (f & j) and mPIN (g, h, k, & l) at 3, 6, 12 and 24 months respectively. A mitotic figure is indicated by an arrow in k. The inset at the upper right corner of h is the magnified area of the nearby square, showing intraepithelial red blood cells. Arrowheads in j-l indicate cytoplasmic hyaline associated with atypia. (B) Representative HE-stained tissue sections from mouse lateral prostates (LPs), anterior prostates (APs) and ventral prostates (VPs). Atbf1\textsuperscript{PE+/+} mice had normal histological phenotypes in these lobes (a-c). Hyperplasia was sometimes detected in Atbf1\textsuperscript{PE+/+} mice (d and e), whereas mPIN was observed in all three lobes with homozygous deletion of \textit{Atbf1} (Atbf1\textsuperscript{PE-/-}) (g-i). All scale bars are 100 μm. mouse prostatic epithelium, and found that *Atbf1* deletion induced mPIN in mice, providing for the first time direct evidence for a tumor suppressor function of *Atbf1*. Hyperplasia was detected as early as 4 months of age, and mPIN occurred when *Atbf1PE-/−* mice aged. *Atbf1* deletion-induced mPIN had established mPIN features such as prominent nucleoli, abundant pale cytoplasm, severe pleomorphism, association with host inflammatory responses, and discontinuity of the fibromuscular sheath [27]. Another feature in the *Atbf1*-null mPIN was severe atypical cytoplasmic hyaline, which is seen sometimes in human prostate cancer [38] but rarely in mPIN induced by the knockout of Figure 3. Cell proliferation analysis and molecular characterization of mPIN lesions induced by homozygous deletion of *Atbf1*. (A) Evaluation of cell proliferation by detecting Ki67-positive cells with immunohistochemical staining. The percentage of Ki67-positive cells in the epithelium of a DP was plotted against *Atbf1* genotype (circular-, squared- and triangle-shaped boxes for *Atbf1PE+/+*, *Atbf1PE+/−* and *Atbf1PE−/−* respectively), and mean values are indicated by horizontal lines. An increase in Ki67-positive cells is seen in hyperplasia and mPIN lesions. *, *P* = 0.0001. **, *P* < 0.0001. (B) Homozygous deletion of *Atbf1* (*Atbf1PE−/−*) changed the expression of molecules involved in different characteristics of prostate and prostate cancer, including luminal-basal-stroma architectural markers cytokeratin 5 (Ck5), Ck18, E-cadherin (Cdh1), and smooth muscle actin (Sma); epithelial differentiation markers androgen receptor (Ar); oncogenic signaling molecules phospho-Erk1/2 (p-Erk1/2) and phospho-Akt (p-Akt); and glycoprotein mucin 1 (Muc1) and glycosylation marker Tn antigen (the upper and lower Tn panels were detected by the antibody and HPA methods respectively). DPs with mPIN from 24-month-old mice were used for Ck5, Ck18, E-cadherin, Sma and Ar, while those of 12-month-old mice were used for p-Erk1/2, p-Akt, Muc1 and Tn antigen. Immunofluorescent staining with nuclei counterstained with DAPI (blue) was used for Tn detection, while immunohistochemical staining was performed for the rest of the molecules. Note the attenuation or loss of Ck5, Cdh1 and Sma, as indicated by arrows and magnified regions at the upper right corner of respective images. Also note the appearance of both p-Erk1/2 and p-Akt (pointed by arrows) and significant increase in Muc1 and Tn antigen expression in mPIN lesions with *Atbf1* deletion. All scale bars are 100 μm. Neoplasia Vol. 16, No. 5, 2014 Deletion of *Atbf1* causes mPIN in mouse prostates Sun et al. 383 other tumor suppressor genes [27]. In human prostates, PIN has been widely considered as a precursor of prostate adenocarcinoma [39], and many known oncogenic genetic events induce mPIN rather than invasive carcinoma in mouse prostates [40,41]. Therefore, induction of mPIN by Atbf1 deletion provides functional evidence for Atbf1 tumor suppressor activity. No invasive prostate cancer was detected in any of the Atbf1PE-/- mice even at 25 months old, which has been common for many known tumor suppressor genes including p53, Rb, Nkx3.1, Maspin, Brca2 and p27Kip, whose deletion alone only causes mPIN lesions [42–47]. It is well recognized that multiple genetic and epigenetic alterations are usually required for an invasive cancer to develop. While Atbf1 deletion **Figure 4. Validation of dysregulated genes by homozygous deletion of Atbf1 in mouse dorsal prostates (DPs).** Expression of upregulated (A) and downregulated genes (B) was analyzed by real-time RT-PCR (A, B), with 2 genes’ protein expression also evaluated by immunohistochemical staining (C). In the real-time RT-PCR assay, the relative gene expression levels were plotted as circular (Atbf1PE+/+), squared (Atbf1PE+-) and triangle (Atbf1PE-) shaped boxes respectively, and mean values are indicated by lines. For each gene, the average expression level in Atbf1PE+/- was set to 1, and levels in each individual were adjusted accordingly. Asterisks indicate two genes (Gabra4 and Mcm10) expressed at intermediate levels in Atbf1PE-/- mice, which indicates haploinsufficiency for these genes. Scale bars in panel C are 100 μm. alone appears to be insufficient to induce invasive prostate cancer, it could cooperate with other oncogenic events to induce invasive carcinoma. We are in the process of testing whether \textit{Atbf1} deletion cooperates with \textit{Pten} deletion, a well characterized oncogenic event in prostate cancer\cite{48}, in the development and progression of prostate cancer. \textit{Atbf1} Deletion-Induced mPIN Lesions Share Multiple Morphological and Molecular Characteristics with Human Prostate Cancer Mouse DP is anatomically and biochemically closest to the peripheral zone of human prostate\cite{49}, and most human prostate cancers arise from the peripheral zone of prostate\cite{50}. Thus finding of the most severe histopathological lesions in the DP of \textit{Atbf1 PE2} mice (Figures 1, 2) indicates a reasonable relevance of \textit{Atbf1} deletion-induced mPIN to human prostate cancer. Another histological change that also occurs in human prostate cancer is the interruption of the fibromuscular layer in \textit{Atbf1} deletion-induced mPIN lesions, as indicated by attenuated expression of the Sma smooth muscle marker (Figure 3B). Shared cellular and molecular characteristics further indicate the relevance of \textit{Atbf1} deletion-induced mPIN lesion to human prostate cancer. One shared characteristic is increased cell proliferation, as indicated by the increase in Ki67-positive cells in \textit{Atbf1}–null prostates (Figure 3A). In human prostate cancer, an increased Ki67 proliferation index correlates with higher tumor grade and worse patient survival\cite{51}. \textit{Atbf1} deletion-induced mPIN lesions also maintained luminal characteristics as seen in most human prostate cancers, indicated by the positive staining of luminal markers Ck18 and Ar and decreased staining of the Ck5 basal cell marker (Figure 3B). Multiple molecular alterations reported in human prostate cancer also occurred in \textit{Atbf1} deletion-induced mPIN lesions. For example, the cell-cell adhesion molecule E-cadherin, which is often downregulated in human prostate cancer\cite{52}, was also downregulated in mPIN lesions induced by \textit{Atbf1} deletion (Figure 3B). expression of activated Erk1/2 and Akt (i.e., phosphorylated Erk1/2 and Akt), which mediate two common oncogenic signaling pathways and often occur in human prostate cancer and other mouse models of prostate cancer [53–56], was also detected in Atbf1-null mPIN (Figure 3B). Another example is the upregulation of Muc1 by Atbf1 deletion (Figure 3B), which also occurs in human primary and metastatic prostate cancers and suggests Muc1 as a potential therapeutic target for cancer treatment [33,35,36]. MUC1 is a major cell surface protein that functions as a physical and biological barrier to protect mucous epithelia, and interacts with a number of proteins to trigger diverse signaling pathways including the MAPK/ERK pathway [33,37]. Overexpression of Muc1 alone in mouse mammary glands can also lead to increased ERK1/2 activity [58]. Thirdly, Atbf1 deletion led to the expression of the Tn antigen (Figure 3B), an O-glycan that is usually found on cancer cells but not on normal cells [29,59]. Altered glycosylation in cancer cells could affect MUC1 distribution and signaling [35]. These molecular similarities between Atbf1 deletion-induced mPIN lesions and human prostate cancer indicate the model's intrinsic relevance. **Atbf1 Deficiency Attenuates the Secretory Profile of Mouse Prostates** ATBF1 is a transcription factor, and we would thus expect that Atbf1 deletion in mouse prostates dysregulates a number of genes. This is indeed the case, as hundreds of genes, 391 of which are protein-coding, were differentially expressed between normal prostates and Atbf1-null prostates (Table S2). Some differentially expressed genes, including Clu, Qox1, Hk2 and Tactos2, were also identified in mouse prostates with the knockout of Nkx3.1 or Pten, both of which have a tumor suppressor function in prostate cancer [48,60,61]. Interestingly, 64 of the 391 (16%) differentially expressed proteins were annotated as secretory proteins and 117 of them (29.9%) have been detected in the plasma or serum (Table S2). We verified the elevation of two secretory proteins, Clu and Spink3, by IHC staining in mouse DPs. Clu was also usually found on cancer cells but not on normal cells [29,59]. Altered glycosylation in cancer cells could affect MUC1 distribution and signaling [35]. These molecular similarities between Atbf1 deletion-induced mPIN lesions and human prostate cancer indicate the model's intrinsic relevance. **Atbf1 Deletion Leads to Abnormalities in Multiple Signaling Pathways Involved in Carcinogenesis** Some of the secretory proteins dysregulated by Atbf1 deletion, including IGF1 (Tables S2), are known signaling molecules. In addition, 101 of the 391 (25.8%) differentially expressed proteins between normal and Atbf1-null prostates have been reported as membrane proteins (Table S2), including receptors (e.g., Prlr and Ptger3), cell surface antigens (e.g., Ly6e), and ion channels and transporters (e.g., Skca2a4, Trpv6, and Atpl2a) (Table S2). Ion channel and transporter proteins affect the concentration of extracellular and intracellular cations to regulate a broad range of biological events related to cancer, including cell proliferation, apoptosis and migration [67]. Whereas some of the ion channel proteins are dysregulated in human prostate cancer, e.g., TRPV6 is upregulated in advanced prostate tumors to increase Ca2+ entry [68], many of the differentially expressed proteins such as PrlR and RGS3 are known to influence cellular signaling. It is thus possible that Atbf1 deletion attenuates multiple signaling pathways and networks, and the pathway analyses support this prediction (Figure 5, Table S4). When differentially expressed genes between normal and Atbf1-null prostates and their expression levels were examined with the Ingenuity Pathway Analysis (IPA) program, a number of signaling pathways/networks were identified (Table S4), and these pathways regulate multiple biological processes including cell differentiation, tissue development, cell death, cell movement, secretion of bodily fluid, cation transport, atrial fibrillation and blood pressure regulation (Table S4). The four with the highest statistical significance centered on ERK1/2-IGF1, AKT-FSH, NF-κB and progesterone-β-estradiol (Figure 5), and each of these four networks has been implicated in cancer development. For example, activated ERK1/2 and AKT, two well established oncogenic molecules that can be activated by a number of genetic events during carcinogenesis, were also detectable in Atbf1 deletion-induced mPIN lesions (Figure 3B). For the network centered on ERK1/2 and IGF1, there were multiple molecules linking them (Figure 5A), but whether and how these two nodes truly interact are unknown, although higher serum concentrations of IGF1 are associated with an increased risk of several types of cancers including prostate cancer [69], and IGF1 signaling involves the activation of ERK1/2 [70]. For the network centered on follicle-stimulating hormone (FSH) and AKT (Figure 5B), the FSH hormone is known to act on granulosa cells within the immature follicle to promote proliferation, inhibit apoptosis, and stimulate hormone production; and multiple signaling pathways including the PI3K/AKT pathway are involved in FSH function [71,72]. FSH also stimulates the PI3K-dependent pathway in the proliferation and differentiation of Sertoli cells [73,74] and meiotic maturation of oocytes [75]. Interestingly, in addition to androgens, FSH is another hormone that influences the pathogenesis and progression of prostate cancer, as FSH and its receptors are upregulated in prostate cancer and the serum level of FSH is associated with extraprostatic extension of prostate cancer [76,77]. Therefore, increased FSH hormonal signaling activity and subsequent PI3K/AKT activation could be one of the major pathways that mediate the effect of Atbf1 deletion on prostatic tumorigenesis. Another signaling network attenuated by Atbf1 deletion focused on NF-κB (Figure 5C), which often has increased activity in human cancers and thus has been considered a therapeutic target in cancer treatment [78]. In human prostate cancer, NF-κB is constitutively active in a subset of castration-resistant prostate cancers, and NF-κB overexpression significantly associates with shorter patient survival [79,80]. Human prostate cancer cell lines also have constitutively active NF-κB [81], and inhibition of NF-κB activity inhibited their growth in xenograft models, decreased bone resorption of prostate cancer cells co-cultured with bone marrow, and reduced their invasive capability [82,83]. Interestingly, ATBF1 is the second most frequently mutated gene in castration-resistant human prostate cancer [9,10]. Taken together, it is possible that inactivation of ATBF1 in human prostate cancer activates NF-κB signaling to induce and/or promote the progression of prostate cancer to an androgen-independent and/or metastatic state. in vivo deletion on estrogen signaling, our previous studies demonstrated that estrogen- and progesterone receptors in prostate cancer have been documented [84], and so has the role of estrogen in the development and progression of prostate cancer [85,86]. For example, androgen-responsive LNCap prostate cancer cells are stimulated by estradiol for growth via estrogen receptors while the androgen-insensitive PC-3 prostate cancer cell proliferation is inhibited by estrogen [85]. Human prostate expresses both ERα and ERβ, which are dysregulated during the development and progression of prostate cancer. ERα is often upregulated to mediate the oncogenic effects of estradiol, which also involves the estrogen-regulated progesterone receptor (PR), during prostate cancer progression [87]. On the other hand, ERβ is downregulated in castration-resistant prostate cancer and thus serves as a tumor suppressor [87]. ERβ mediates the inhibitory effect of antiestrogens on the development of castration-resistant prostate cancer by interacting with other transcription factors to upregulate FOXO1, inducing anoikis and thus suppressing the growth of prostate cancer [88]. The role of estrogen and progesterone in prostate cancer is better documented in mouse models [86]. Further supporting the effect of Abf1 deletion on estrogen signaling, our previous studies demonstrated that in breast cancer cells estrogen signaling upregulates ATBF1 transcription but causes ATBF1 protein degradation [89,90], while ATBF1 inhibits ERα function by selectively competing with one of its coactivators for the binding to ERα [91]. Abf1 deletion increased cell proliferation only in ERα-positive but not in ERα-negative cells [92] and the Pg-progesterone signaling upregulates ATBF1 in mammary epithelial cells [93]. All these findings suggest the possibility that Abf1 suppresses ERα signaling in normal prostates and Abf1 deletion leads to more active estrogen signaling that could promote the development and progression of prostate cancer. The fifth most significant network based on the P value was the network of 9 genes involved in atrial fibrillation (Table S4), a common heart rhythm disorder. The role of ATBF1 in atrial fibrillation has been suggested by a genetic association of ATBF1 sequence variants with this disorder [5,6], and the 9 genes regulated by Atbf1 provide a clue for how ATBF1 mutation may modulate atrial fibrillation. In summary, we found that deletion of Abf1 in mouse prostates caused mPIN lesions, and the mPIN lesions shared a number of histopathologic and molecular features with human PIN and prostate cancer, providing functional evidence for a tumor suppressor activity of ATBF1 in human prostate cancer and establishing a mouse model of prostatic carcinogenesis that is relevant to human prostate cancer. In addition, a number of genes, particularly those encoding for cell membrane and secretory proteins, were dysregulated by Abf1 deletion, and the most affected signaling networks centered on Erk1/2 and IGF1, Akt and FSH, NF-κB and progesterone and β-estradiol, all of which have been implicated in human cancer development. These findings provide in vivo evidence that ATBF1 is a tumor suppressor in the prostate, suggest that loss of Abf1 contributes to tumorigenesis by dysregulating membrane and secretory proteins and multiple signaling pathways, and provide a new and clinically relevant animal model for prostate cancer. Acknowledgments The authors thank Dr. Robert Cardiff of University of California at Davis for pathological diagnosis; Drs. Leon Bernal-Mizrachi and Jeanne Kowalski for their help in the design and analysis of microarray experiments; Drs. Wei Zhou, Michael M. Shen, and Song-Qing Fan for valuable discussions; and Drs. Lori King and Anthea Hammond for manuscript editing. This work was supported by National Institutes of Health grant CA121459 (to JT Dong). Supplementary Data Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.neo.2014.05.001. References Neoplasia Vol. 16, No. 5, 2014 Deletion of Atbf1 causes mPIN in mouse prostates Sun et al.
We are IntechOpen, the world’s leading publisher of Open Access books Built by scientists, for scientists 6,600 Open access books available 177,000 International authors and editors 195M Downloads 154 Countries delivered to TOP 1% Our authors are among the most cited scientists 12.2% Contributors from top 500 universities WEB OF SCIENCE™ Selection of our books indexed in the Book Citation Index in Web of Science™ Core Collection (BKCI) Interested in publishing with us? Contact book.department@intechopen.com Numbers displayed above are based on latest data collected. For more information visit www.intechopen.com Vector Space Information Retrieval Techniques for Bioinformatics Data Mining Eric Sakk and Iyanuoluwa E. Odebode Department of Computer Science, Morgan State University, Baltimore, MD USA 1. Introduction Information retrieval (IR) can be defined as the set of processes involved in querying a collection of objects in order to extract relevant data and information Dominich (2010); Grossman & Frieder (2004). Within this paradigm, various models ranging from deterministic to probabilistic have been applied. The goal of this chapter is to invoke a mathematical structure on bioinformatics database objects that facilitates the use of vector space techniques typically encountered in text mining and information retrieval systems Berry & Browne (2005); Langville & Meyer (2006). Several choices and approaches exist for encoding bioinformatics data such that database objects are transformed and embedded in a linear vector space Baldi & Brunak (1998). Hence, part of the key to developing such an approach lies in invoking an algebraic structure that accurately reflects relevant features within a given database. Some attention must therefore be devoted to the numerical encoding of bioinformatics objects such that relevant biological and chemical characteristics are preserved. Furthermore, the structure must also prove useful for operations typical of data mining such as clustering, knowledge discovery and pattern classification. Under these circumstances, the vector space approach affords us the latitude to explore techniques analogous to those applied in text information retrieval Elden (2004); Feldman & Sanger (2007); Grossman & Frieder (2004). While the methods presented in this chapter are quite general and readily applicable to various categories of bioinformatics data such as text, sequence, or structural objects, we focus this work on amino acid sequence data. Specifically, we apply the BLOCKS protein sequence database Henikoff et al. (2000); Pietrokovski et al. (1996) as the template for testing the applied techniques. It is demonstrated that the vector space approach is consistent with pattern search and classification methodologies commonly applied within the bioinformatics literature Baldi & Brunak (1998); Durbin et al. (2004); Wang et al. (2005). In addition, various subspace decomposition approaches are presented and applied to the pattern search and pattern classification problems. To summarize, the main contribution of this work is directed towards bioinformatics data mining. We demonstrate that information measures derived from the vector space approach are consistent with and, in many cases, reduce to those typically applied in the bioinformatics literature. In addition, we apply the BLOCKS database in order to demonstrate database search and information retrieval techniques such as - Pattern Classification The chapter is outlined in Figure 1 as follows. Section 2 provides basic background regarding information retrieval and bioinformatics techniques applied in this work. Given this foundation, Section 3 presents various approaches to encoding bioinformatics sequence data. Section 4 then introduces the subspace decomposition methodology for the vector space approach. Finally, Section 5 develops the approach in the context of various applications listed in Figure 1. ![Flowchart for the chapter](image) **2. Overview and notation** Part of the goal of this chapter is to phrase the bioinformatics database mining problem in terms of vector space IR (information retrieval) techniques; hence, this section is devoted toward reviewing terms and concepts relevant to this work. In addition, definitions, mathematical notation and conventions for elements such as vectors and matrices are introduced. **2.1 Vector space approach to information retrieval** Information retrieval can be thought of as a collection of techniques designed to search through a set of objects (e.g. contained within a database, on the internet, etc) in order to extract information that is relevant to the query. Such techniques are applicable, for example, to the design of search engines, as well as performing data mining, text mining, and text categorization Berry & Browne (2005); Elden (2004); Feldman & Sanger (2007); Hand et al. (2001); Langville & Meyer (2006); Weiss et al. (2005). One specific category of this field that has proven useful for the design of search engines and constructing vector space models for text retrieval is known as Latent Semantic Indexing (LSI) Berry et al. (1999; 1995); Deerwester et al. (1990); Salton & Buckley (1990). Using the LSI approach, textual data is transformed (or ‘encoded’) into numeric vectors. Matrix analysis techniques Golub & Van Loan (1989) are then applied in order to quantify semantic relationships within the textual data. Table 1. Example of a $5 \times 4$ term-document matrix. Consider categorizing a set of $m$ documents based upon the presence or absence of a list of $n$ selected terms. Under these circumstances, an $n \times m$ term-document matrix can be constructed where each entry in the matrix might reflect the weighted frequency of occurrence of each term of interest. Table 1 provides an example; in this case, a matrix column vector defines the frequency of occurrence of each term in a given document. Such a construction immediately facilitates the application of matrix analysis for the sake of quantifying the degree of similarity between a query vector and the document vectors contained within the term-document matrix. Given an $n \times m$ term-document matrix $A$, consider an $n \times 1$ vector $q$ constructed from a query document whose components reflect the presence or absence of entries in the same list of $n$ terms used to construct the matrix $A$. The question then naturally arises how one might quantify the similarity between the query vector $q$ and the term-document matrix $A$. Defining such a similarity measure would immediately lead to a scoring scheme that can be used to order results from most relevant to least relevant (i.e., induce a ‘relevance score’). Given the vector space approach, a natural measure of similarity arises from the inner product. Assuming an $\ell_2$-norm, if both $q$ and the columns of $A$ have been normalized to unit magnitude, then the inner product between $q$ and the $j^{th}$ column vector of $A$ becomes $$q^T a_j = ||q|| \cdot ||a_j|| \cdot \cos \theta_j = \cos \theta_j$$ (1) (where the ‘$T$’ superscript denotes the transpose). Since all components of $q$ and $A$ are non-negative, all inner products will evaluate to a value such that $0 \leq \cos \theta_j \leq 1$. Similar queries approach a value of one indicating a small angle between the query and column vector, dissimilar queries approach a value of zero indicating orthogonality. This specific measure is called the ‘cosine similarity’ and is abbreviated as $$\cos \theta = q^T A$$ (2) where $\cos \theta$ represents a row vector whose components quantify the relevance between the query and each column vector of $A$. Given the vector space approach, LSI (latent semantic indexing) goes a step further in order to infer semantic dependencies that are not immediately obvious from the raw data contained in the term-document matrix. In terms of linear algebra, the LSI methodology translates into characterizing the column space of $A$ based upon some preferred matrix decomposition. A tool commonly applied in this arena is the Singular Value Decomposition (SVD) Golub & Van Loan (1989) where the term-document matrix is factored as follows: $$A = U \Sigma V^T$$ (3) where $U$ is an $n \times n$ orthogonal matrix (i.e. $U^{-1} = U^T$), $V$ is an $m \times m$ orthogonal matrix (i.e. $V^{-1} = V^T$). Furthermore, $\Sigma$ is an $n \times m$ diagonal matrix of singular values such that $$\sigma_1 \geq \sigma_2 \geq \cdots \geq \sigma_r > 0$$ (4) where $r = \text{rank}(A)$ and $\sigma_i \equiv \Sigma_{ii}$. It turns out that the first $r$ columns of $U$ define an orthonormal basis for the column space of the matrix $A$. This basis defines the underlying character of the document vectors and can be used to infer linear dependencies between them. Furthermore, it is possible to expand the matrix $A$ in terms of the SVD: $$A = \sum_{j=1}^{r} \sigma_j u_j v_j^T$$ (5) where $u_j$ and $v_j$ represent the $j^{th}$ columns of $U$ and $V$. This expansion weights each product $u_j v_j^T$ by the associated singular value $\sigma_j$. Hence, if there is a substantial decreasing trend in the singular values such that $\sigma_j / \sigma_1 << 1$ for all $j > L$, one is then led to truncate the above series in order to focus on the first $L$ terms that are responsible for a non-negligible contribution to the expansion. This truncation is called the low rank approximation to $A$: $$A \approx \sum_{j=1}^{L} \sigma_j u_j v_j^T$$ (6) The low rank approximation describes, among other aspects, the degree to which each basis vector in $U$ contributes to the matrix $A$. Furthermore, the subspace defined by the first $L$ columns of $U$ is useful for inferring linear dependencies in the original document space. ### 2.2 Bioinformatics Given this abbreviated overview of vector space approaches to information retrieval, we now put it in the context of bioinformatics research. In particular, the SVD has been applied in many contexts as it can be thought of as a deterministic version of principal component analysis Wall et al. (2003). One specific area of honorable mention is pioneering work dealing with the analysis of microarray data Alter et al. (2000a;b); Kuruvilla et al. (2004). With regard to information retrieval and LSI in bioinformatics Done (2009); Khatri et al. (2005); Klie et al. (2008), research in this area devoted to phylogenetics and multiple sequence alignment Couto et al. (2007); Stuart & Berry (2004); Stuart, Moffett & Baker (2002) has been reported. Much of this work can be traced back to initial foundations where the encoding of protein sequences has been performed using the frequency of occurrence of amino acid $k$-grams Stuart, Moffett & Leader (2002). Using the $k$-gram approach, column vectors in the data matrix (i.e. what was previously referred to as the ‘term-document matrix’) are encoded amino acid sequences and their components are the frequency of occurrence of each possible $k$-gram within each sequence. For example, if amino acids are taken $k = 3$ at a time, then there exist $n = 20^k = 8000$ possible $3$-grams. Assuming there are $m$ amino acid sequences, the associated data matrix will be $n \times m = 8000 \times m$. For each amino acid sequence, a sliding, overlapping window of length $k$ is used to count the frequency of occurrence of each $k$-gram and entered into the data matrix $A$. The goal of this chapter is to build upon the IR and bioinformatics foundation in order to introduce novel perspectives on operations and computations commonly encountered in bioinformatics such as the consensus sequence, position specific scoring matrices (PSSM), 3. Sequence encoding Many choices exist for the encoding of and weighting of entries within the term-document matrix; in addition, there exist a wide range of possibilities for matrix decompositions as well as the construction of similarity and scoring measures Elden (2004); Feldman & Sanger (2007); Hand et al. (2001); Weiss et al. (2005). The goal of this chapter is not to expand on the set of choices for the sake of text retrieval and generic data mining; instead, we must focus on techniques and approaches that are relevant to bioinformatics. Specifically, our attention in this section is devoted toward developing and presenting novel encoding schemes that preserve relevant biological and chemical properties of genomic data. An assortment of methods have been proposed and studied for converting a protein from its amino acid sequence space into a numerical vector Bacardit et al. (2009); Baldi & Brunak (1998); Bordo & Argos (1991); Stuart, Moffett & Leader (2002). Scalar techniques generally assign a real number that relates an amino acid to some physically measurable property (e.g. - volume, charge, hydrophobicity) Andorf et al. (2002); Eisenberg et al. (1984); Kyte & Doolittle (1982); Wimley & White (1996). On the other hand, orthogonal or ‘standard’ vector encoding techniques Baldi & Brunak (1998) embed each amino acid into a $k$ dimensional vector space where $k$ is the number of symbols. For example, if $k = 20$ (as it would be for the complete amino acid alphabet), the $j^{th}$ amino acid where $1 \leq j \leq 20$ is represented by a 20 dimensional vector that is assigned a one at the $j^{th}$ position and zero in every other position. In general, standard encoding transforms a sequence of length $L$ into an $n = Lk$ dimensional vector. As an example consider the DNA alphabet $A = \{A, G, C, T\}$. In this case $k = 4$ and standard encoding transforms the alphabet symbols as $$A = \begin{pmatrix} 1 \\ 0 \\ 0 \\ 0 \end{pmatrix}, \quad G = \begin{pmatrix} 0 \\ 1 \\ 0 \\ 0 \end{pmatrix}, \quad C = \begin{pmatrix} 0 \\ 0 \\ 1 \\ 0 \end{pmatrix}, \quad T = \begin{pmatrix} 0 \\ 0 \\ 0 \\ 1 \end{pmatrix}.$$ \quad (7) Therefore, for an example sequence $s = AT$ with $L = 2$, this encoding method yields the following vector of dimension $n = Lk = 8$: $$x^T = (1 \ 0 \ 0 \ 0 \ 0 \ 0 \ 0 \ 1).$$ Observe that, for typical values of $L$, assuming a data set of $m$ sequences, standard encoding leads to an $n \times m$ data matrix that is sparse. In bioinformatics, given the limitations on biological measurement, the number of experimental observations tends to be limited and values of $m$ are often small with respect to $n$. Under these conditions, it is often the case that vector encoding methodologies lead to sparse data matrices (as is the case for text retrieval applications) in high dimensional vector spaces. Observe, for example, that the $k$-gram method reviewed in Section 2.2 fits this description. We can expand upon the standard encoding approach by categorizing the standard amino acid alphabet into families that take into account physical and chemical characteristics derived from the literature Andorf et al. (2002); Baldi & Brunak (1998). In addition, entries within... the data matrix can be weighted based upon their hydrophobicity Eisenberg et al. (1984); Kyte & Doolittle (1982). Table 2 introduces alphabet symbols used to group amino acids according to hydrophobicity, charge and volume. Tables 3-5 show examples of various encoding schemes that we apply for this analysis. <table> <thead> <tr> <th>Hydrophobicity</th> <th>R=hydrophobic, H=hydrophilic</th> </tr> </thead> <tbody> <tr> <td>Charge</td> <td>P=positive, N=negative, U=uncharged</td> </tr> <tr> <td>Volume</td> <td>S=small, M=medium, ML=medium-large, L=medium</td> </tr> </tbody> </table> Table 2. Encoding symbols applied in Tables 3-5 R 1 A, I, L, M, F, P, W, V, D, E H 3 R, H, K, N, C, Q, G, S, T, Y Table 3. Hydrophobic/Hydrophilic Encoding RU 1 A, I, L, M, F, P, W, V HN 2 D, E HP 3 R, H, K HU 4 N, C, Q, G, S, T, Y Table 4. Charged Hydrophobic/Hydrophilic Encoding RUS 1 A RUM 2 F RUL 4 F, W HPML 5 R, H, K HNML 7 E HUS 8 G, S HUM 9 N, C, V HUML 10 Q HUL 11 Y Table 5. Volume/Charged Hydrophobic/Hydrophilic Encoding 4. Subspace decompositions for pattern classification LSI techniques necessarily require the application of matrix decompositions such as the SVD to infer column vector dependencies in the data matrix. Decompositions of this kind can lead to the construction of subspaces that can mathematically categorize subsets of sequences into families. Furthermore, since these families define specific classes of data, they can be used as training data in order to perform database searches and pattern classification. The application of linear subspaces for the sake of pattern classification Oja (1983) consists of applying orthogonal projection operators based upon the training classes (an orthogonal projection operator \( P \) obeys \( P = P^T \) and \( P^2 = P \)). 4.1 Orthogonal projections To begin, let us assume there are training sequences of known classification that can be categorized into \( M \) distinct classes and that the \( i \)th class contains \( m_i \) encoded vectors of dimension \( n \). For each class, an \( n \times m_i \) matrix \( A_i \) can be constructed (assuming the training vectors are column vectors). To characterize the linear subspace generated by each class, we can apply the singular value decomposition (SVD) Golub & Van Loan (1989). In addition to providing us with an orthonormal basis for each class, we can also glean some information about the influence of the singular values and singular vectors from the rank approximants. Class data matrices are therefore decomposed as \[ A_i = U_i \Sigma_i V_i^T \] (8) where \( U_i \) is \( n \times n \) orthogonal matrix, \( \Sigma_i \) is \( n \times m_i \) whose diagonal contains the singular values and \( V_i \) is an \( m_i \times m_i \) orthogonal matrix. Assume the rank of each data matrix \( A_i \) is \( r_i \) and let \( Q_i \) denote the \( n \times r_i \) matrix formed from first \( r_i \) columns of \( U_i \). Given the properties of the SVD, the columns of \( Q_i \) define an orthonormal basis for the column space of \( A_i \). Hence, an orthogonal projection operator for the \( i \)th class is established by computing \[ P_i = Q_i Q_i^T. \] (9) (given that the SVD induces \( U_i^T = U_i^{-1} \), it is straightforward to check that \( P_i^2 = P_i \) and \( P_i^T = P_i \)). Consider an \( n \times 1 \) query vector \( x \) whose classification is unknown. The class membership of \( x \) can be ascertained by identifying the class yielding the maximum projection norm: \[ C(x) \equiv \arg \max_{i=1,\ldots,M} ||P_i x||. \] (10) One computational convenience of constructing the orthonormal bases \( Q_i \) is that it is not necessary to compute the projections when making this decision. Given any \( Q \) with orthonormal columns and orthogonal projection \( P = QQ^T \) such that \( P^2 = P \) and \( P = P^T \), observ \[ ||P x||^2 = x^T P^T P x = x^T P^2 x =x^T P x = x^T Q Q^T x = ||Q^T x||^2 = ||x^T Q||^2. \] (11) Under these circumstances, to decide class membership, Equation (10) reduces to \[ C(x) \equiv \arg \max_{i=1,\ldots,M} ||x^T Q_i||. \] (12) Furthermore, the values \( ||x^T Q_i|| \) immediately yield relevance scores and confidence measures for each class. 4.2 Characterization of the orthogonal complement It is important to note that the union of all the class subspaces need not be equal to the \( n \) dimensional vector space from which all data vectors are derived. To perform a complete orthogonal decomposition of the \( n \) dimensional vector space in terms of the data, we first define the matrix \[ A \equiv [A_1 \cdots A_M]. \] (13) The goal then is to characterize the null space \( N(A^T) \), the subspace which is orthogonal to the column space of \( A \). Assuming the rank of \( A \) is \( r_A \), computing the SVD \[ A = U_A \Sigma_A V_A^T \] (14) and forming the matrix \( Q_A \) from the the first \( r_A \) columns of \( U_A \) yields an orthogonal decomposition of the subspace generated by all class vectors. Hence, a projection operator for this subspace is constructed as \[ P_A = Q_A Q_A^T. \tag{15} \] In addition, a projection for the orthogonal complement \( N(Q_A^T) \) of \( A \) is then easily formed via \[ P_{A \perp} = I_{n} - P_A \] (16) where \( I_n \) is the \( n \times n \) identity matrix. A complete orthogonal decomposition Lay (2005) of a vector \( x \in \mathbb{R}^n \) can then be determined from \[ x = P_A x + P_{A \perp} x. \tag{17} \] 4.3 Information retrieval Before attempting to decide the class membership of a vector \( x \in \mathbb{R}^n \) based upon Equation (12), it is sensible to characterize the portion of the vector that contributes to the class subspace defined by \( Q_A \). Given Equation (17), this is most easily done by comparing \( ||P_A x|| \) with \( ||P_{A \perp} x|| \) as \[ \tan(\phi) = \frac{||P_{A \perp} x||}{||P_A x||} \tag{18} \] where \( \phi \) is the angle between \( x \) and the subspace defined by \( Q_A \). Ideally, if the class subspaces have been completely characterized, \( \tan(\phi) \) should be small. Conversely, larger values of \( \tan(\phi) \) would indicate that \( x \) is a member of a class subspace that has not yet been defined. Under these circumstances, the orthogonal complement would have to be further characterized and partitioned in order to define more classes beyond the known \( M \) existing classes. It is also possible to phrase the tangent measure as a scalar version of the more familiar cosine similarity defined above in Equation (2). If \( ||x|| = 1 \), the cosine similarity measure takes on a convenient form \[ \cos(\phi) = ||x^T Q_A||. \tag{19} \] To see why, consider the inner product \[ x^T (P_A x) = \langle x \cdot P_A x \rangle = ||x|| \cdot ||P_A x|| \cdot \cos(\phi). \tag{20} \] If \( ||x|| = 1 \), then \[ \cos(\phi) = \frac{x^T P_A x}{||P_A x||}. \tag{21} \] However, since $P_A$ is an orthogonal projection \[ \|P_Ax\| = \sqrt{x^TP_A^TP_Ax} = \sqrt{x^TP_Ax} \] and Equation (21) can therefore be rewritten as \[ \cos(\phi) = \sqrt{x^TP_Ax}. \] (23) On the other hand, by applying Equation (11) to Equation (22), it follows that \[ \|x^TQ_A\| = \sqrt{x^TP_Ax} \] (24) as well; hence, the equality of Equations (23) and (24) establishes Equation (19). Equation (19) should also be clear from the geometric fact that \[ \cos(\phi) = \frac{\|P_Ax\|}{\|x\|}. \] (25) Assuming $\|x\| = 1$, Equation (19) then easily follows by applying Equation (11) to Equation (25). Equations (23) and (24) are presented in order to offer additional insight by relating the inner product to the projection operator. Of central focus in the next section will be to apply the above projection framework to information retrieval in bioinformatics. Since the classification problem will be of significance, we note that, given the identity in Equation (19), Equation (12) can be rephrased in term of the cosine similarity measure \[ C(x) \equiv \arg \max_{i=1,\cdots,M} \cos(\phi_i) \] (26) where \[ \cos(\phi_i) \equiv \|x^TQ_i\|. \] (27) In addition, this measure of class membership becomes more reliable if the contribution of $x$ to the orthogonal complement of the data set is small. For instance, when $\phi$ is small, $\cos(\phi)$ in Equation (19) approaches unity. Therefore, $\cos(\phi)$ can be applied as a measure of data set reliability while $\cos(\phi_i)$ can be used to produce relevance scores for $i = 1, \cdots, M$. These conclusions are summarized in Table 6. <table> <thead> <tr> <th>Similarity Measure</th> <th>Purpose</th> <th>Reference</th> </tr> </thead> <tbody> <tr> <td>$\cos(\phi)$</td> <td>Data Set Reliability</td> <td>Equation (19)</td> </tr> <tr> <td>$\cos(\phi_i)$</td> <td>Relevance Score</td> <td>Equations (26) - (27)</td> </tr> </tbody> </table> Table 6. Reliability and relevance measures to be applied in Section 5. 5. Applications In bioinformatics, families with similar biological function are often formed from sets of protein or nucleic acid sequences. For example, databases such as Pfam Finn et al. (2010), PROSITE Sigrist et al. (2010) and BLOCKS Pietrokovskii et al. (1996) categorize sequence domains of similar function into distinct classes. Given the encodings discussed in Section 3, we seek to demonstrate how Equations (19) and (26) can applied in order to perform sequence modeling, pattern classification and database search computations typically encountered in bioinformatics Baxevanis & Ouellette (2005); Durbin et al. (2004); Mount (2004). 5.1 Consensus sequence A set of \( m \) sequences of length \( L \) having some related function (e.g. DNA promoter sites for a common sigma factor) is often represented in the form of an \( m \times L \) matrix where each column refers to a common position in each sequence. A consensus sequence \( s_C \) of length \( L \) is constructed by extracting the symbol having the highest frequency in each column. This approach to sequence model construction, while quite rudimentary, is often useful for visualizing obvious qualitative relationships amongst sequence elements. Using the vector space approach, it is possible to recover the consensus sequence. Assuming each sequence symbol is encoded into a \( k \) dimensional vector, each sequence will be encoded into a vector of length \( n = Lk \) (see Section 3). Hence the original \( m \times L \) matrix of sequences will be transformed into an \( n \times m \) data matrix of the form described in Section 2.1. In this case, each column vector in the data matrix represents an encoded amino acid sequence. To recover the consensus, it is useful to introduce notation for describing an empirically derived average vector \( \mu_A \) from an \( n \times m \) data matrix \( A \) as follows: \[ \mu_A \equiv \left( \frac{1}{m} \right) A e \] where \( e \) and \( m \times 1 \) vector of ones. Then, \( \mu_A \) is an \( n \times 1 \) column vector made up of \( L \) contiguous 'subvectors' of dimension \( k \) where the value of \( k \) depends upon the encoding method applied. Let \( \nu_i \) for \( i = 1, \ldots, L \) represent each subvector in \( \mu_A \); then, the \( i^{th} \) symbol in the consensus sequence \( s_C(i) \) can be inferred by associating the component of \( \nu_i \) yielding the highest average with the originally encoded symbol. To be precise, let the alphabet of \( k \) sequence symbols (e.g. DNA, amino acids, structural, text, etc) be defined as \[ A \equiv \{ a_1, a_2, \ldots, a_k \} \] and let the \( j^{th} \) component of \( \nu_i \) be written as \( \nu_{ij} \) for \( j = 1, \ldots, k \). The subscript index of the component with the maximum average in \( \nu_i \) can therefore be extracted as \[ J = \arg \max_{j=1,\ldots,k} \nu_{ij} \] and the associated alphabet symbol is entered into the \( i^{th} \) position of the consensus sequence as \[ s_C(i) = a_J \] where \( a_J \in A \). The algorithm for recovering the consensus sequence can be summarized as follows: 1. Given the \( n \times m \) encoded data matrix \( A \), compute \( \mu_A \). 2. For each \( \nu_i \) where \( i = 1, \ldots, L \), apply Equation (30). 3. Given the alphabet \( A \), apply Equation (31) in order to construct the consensus sequence \( s_C \). 5.2 Position specific scoring matrix The consensus sequence, while qualitatively useful, is an incomplete sequence model in that it does not consider cases where two or more symbols in a given position are close to equiprobable. Under these circumstances, one is forced to arbitrarily choose one symbol for the consensus at the expense of loosing information about the other symbols. In contrast, the position specific scoring matrix (PSSM) is a sequence model that considers the frequency of occurrence of all symbols in each position. Furthermore, the PSSM can be used to score and rank sequences of unknown function in order to quantify their similarity to the sequence model. Given an $m \times L$ matrix of $m$ related sequences of length $L$ and an alphabet of $k$ symbols, a $k \times L$ ‘profile’ matrix of empirical probabilities is first constructed by computing the symbol frequency for each position. The profile matrix can be thought of as the preimage of the PSSM. While it can provide important statistical details regarding the sequence model, it does not have the capability to score sequences in an additive fashion position by position. To do this requires converting the profile into a $k \times L$ PSSM of additive information scores. Given a sequence $s$ of length $L$, the PSSM can then be used to compute a score for $s$ in order to determine its relationship to the sequence model. Recovering the PSSM from the vector space approach is straightforward. Given an $n \times m$ data matrix of encoded sequences, the $i^{th}$ subvector $v_i$ in the average vector $\mu_A$ computed from Equation (28) is equivalent to the $i^{th}$ column in the $k \times L$ profile matrix. Simply reshaping the $kL \times 1$ vector $\mu_A$ into a $k \times L$ matrix recovers the profile. However, since the goal is to score sequences of unknown function, we are more interested in showing how $\mu_A$ can be applied to recover a PSSM score. Assume that the components of $\mu_A$ have been transformed by applying the same information measure $I_{PSSM}$ used to convert the profile to the PSSM. Assuming an encoding alphabet with $k$ symbols, a query sequence $s$ of length $L$ can be encoded to form a $kL \times 1$ vector $x$. The PSSM score $S_{PSSM}$ of $x$ can then be recovered via the inner product: $$S_{PSSM} = x^T I_{PSSM}(\mu_A)$$ where $I_{PSSM}(\mu_A)$ represents the conversion of a probability vector into an vector of additive information scores. The similarity of Equation (32) with Equation (2) is worth noting. Assume several families of sequences of equal length $L$ are encoded into separate data matrices $A_i$ where $i = 1, \cdots, M$ and $M$ is the number of families. It should be clear that the relevance score for the query vector $x$ can be produced using the cosine similarity according to $$S_{PSSM} = x^T I_{PSSM}$$ where $$I_{PSSM} = [I_{PSSM}(\mu_{A_1}) I_{PSSM}(\mu_{A_2}) \cdots I_{PSSM}(\mu_{A_M})]$$ is the $n \times M$ information matrix that describes the sequence families. It is of important theoretical interest that the vector space approach recovers both the PSSM and its information capacity to score sequences. However, it is more useful to observe that invoking an algebraic structure on a set of sequences induces a spectrum of novel possibilities. For instance, the SVD can be applied to the data matrix and a scoring scheme can be derived from the computed orthogonal basis. In addition, as mentioned at the end of Section 3, it is possible to weight both the data matrix and the encoded sequence according to more biologically significant measures such as hydrophobicity. Finally, and probably most importantly, the vector space formulation allows for powerful optimization techniques Golub & Van Loan (1989); Luenberger (1969) to be applied in order to maximize the scoring capacity of the sequence model. 5.3 Clustering Our goal in this section is to investigate how clustering encoded sets of vectors will partition an existing set of data. While there are several approaches to performing data clustering Theodoridis & Koutroumbas (2003), we choose to invoke techniques that characterize the mean behavior of a data cluster. Specifically, we analyze one supervised method (Section 5.3.2) and one unsupervised method (Section 5.3.3). As we shall see, these approaches will enable us to construct ‘fuzzy’ regular expressions capable of algebraically describing the behavior of a given data set. It will become clear that this approach will offer additional insight to sequence clustering techniques typically encountered in the literature Henikoff & Henikoff (1991); Smith et al. (1990). As the BLOCKS database Henikoff et al. (2000); Pietrokovski et al. (1996) has been constructed from sequence clusters using ungapped multiple alignment, we choose to apply this database as the template in order to compare it against the vector space model. 5.3.1 The BLOCKS database The BLOCKS database consists of approximately 3000 protein families (or ‘blocks’). Each family has a varying number of sequences that have been derived from ungapped alignments. Therefore, while sequence lengths between two different families may differ, sequences contained within each family, by the definition of a ‘block’, must all have the same length. Furthermore, the number of sequences in each family can vary and there is can be a considerable degree of redundancy within some families; hence, it is sensible to analyze how the data is distributed with respect to each BLOCKS family. The histogram in Figure 2 illustrates the number of BLOCKS families as function of sequence length. For example, there are 90 families containing sequences of length $L = 40$. From this figure, we can conclude that it is generally possible to find at least 40 families containing nominal sequence lengths. It is also important to characterize how the number of sequences contained within each family is distributed throughout the database. The histogram in Figure 3 illustrates the number of BLOCKS families as function of the number of sequences contained within each family. From this figure, we observe that many families contain somewhere between 9 and 20 representative sequences. Finally, for the sake of clarity, we restrict our attention to sequences having the same lengths. The extension of these results to variable length sequences is the subject of current research based upon existing methodologies cited in the literature Couto et al. (2007); T. Rodrigues (2004). The histogram in Figure 4 illustrates the number of BLOCKS families as function of the number of sequences contained within each family; however, observe that this representative sample has been restricted to those families containing sequences of equal length (in this case $L = 30$). The behavior in this graph is typical in that most families contain on the order of 10-12 sequences of equal length. For the purposes of illustration and without loss of generality, we choose to demonstrate the techniques in the upcoming sections using families containing sequences of equal length. 5.3.2 Centroid approach In this section, we cluster sequences whose BLOCKS classification is known a priori in order to algebraically characterize each family. To do this, each family in the analysis is encoded separately and Equation (28) is applied to each family data matrix in order to derive a family centroid. Since the families are already partitioned, this approach is a supervised clustering technique that will enable us to derive symbol contributions from the centroid vectors. Fig. 2. Histogram of the number of BLOCKS families as function of sequence length. Fig. 3. Histogram of the number of BLOCKS families as function of the number of sequences contained in each family. Fig. 4. Histogram of the number of BLOCKS families as function of the number of sequences contained in each family (restricted to families with sequences of length $L=30$). For this numerical experiment, we apply Table 5 as the encoding scheme and choose the BLOCKS family sequence length to be $L = 30$. Under these conditions, sequences will be encoded into column vectors of dimension $n = (30)(11) = 330$. In addition, all encoded data vectors are normalized to have unit magnitude. There are 73 families in the BLOCKS database that have block length $L = 30$. Furthermore, there are a total of 910 sequences distributed amongst the 73 families. As mentioned above, there is a small degree of sequence redundancy within some BLOCKS families. After removing redundant sequences, a total of $J = 755$ sequences of length $L = 30$ are distributed amongst $I = 73$ families. Given the encoding method, the dimensions of the non-redundant data matrix $A$ will be $330 \times 755$. Figure 5 shows the results of computing the distance between all centroids. From this histogram, we observe that database families are fairly well-separated since the minimum distance between any two centroids is greater than 0.6. In order to analyze the performance of the encoding method, we apply the inner product. Specifically, each data vector $v_j$ is classified by choosing the family associated with the centroid yielding the largest inner product: $$ C(v_j) \equiv \arg \max_{i=1,\cdots,I} v_j^T M. $$ where $j = 1, \cdots, J$ and $$ M = [\mu_{A_1}, \mu_{A_2}, \cdots, \mu_{A_I}] $$ For standard encoding (i.e. $k = 20$, $n = 600$), all 755 data vectors were classified correctly using Equation (35). On the other hand, when applying the encoding method in Table 5, there was one misclassification. Figure 6 illustrates that data vector number 431 (which as member of family 30, 'HlyD family secretion proteins') was misclassified into family 54 (Osteopontin proteins). So, while the vector dimension is reduced from 600 to 330 (because \( k \) is reduced from 20 to 11), a minor cost in classification accuracy is incurred. At the same time, we observe a substantial reduction in dimensionality. We note one final application of the centroid approach for deriving 'fuzzy' regular expressions extracted from the vector components of the centroid vectors. Consider the sum normalized \( i \)th family centroid \[ N_{Ai} \equiv \left( \frac{1}{\sum_{j}(\mu_{Aj})} \right) \mu_{Ai}. \] (37) For each subvector associated with each sequence position in \( N_{Ai} \), it is then possible to write an expression describing the percentage contribution of each symbol to analytically characterize the \( i \)th sequence family. 5.3.3 K-means approach In contrast to the supervised approach, we now wish to take all sequences of length \( L \) in the database and investigate how they are clustered when the unsupervised K-means algorithm is applied. When this algorithm is applied to small numbers of families (e.g. < 10), our results indicate that this algorithm will accurately determine the sequence families for the encoding method presented. However, as the number of data vectors grow, the high-dimensionality of the encoding method tends to obscure distances and, hence, can obscure the clusters. We briefly address this issue in the conclusions section of this chapter. 5.4 Database search and pattern classification We now come to what is arguably one of the most important applications in this chapter. In this section, we will apply the reliability and relevance measures summarized in Table 6 to perform BLOCKS database searches and pattern classification Bishop (2006); Hand et al. (2001). 5.4.1 Characterization of BLOCKS orthogonal complement When constructing a database, it is critical to understand and analytically characterize the spectrum of objects not contained within the database. This task is easily achieved by considering the orthogonal complement. As first step, we consider families with sequence lengths \( L = 15 \) (70 families) and \( L = 30 \) (73 families). Furthermore, we compare encodings from Table 3 and Table 5 with standard encoding. Specifically, for each encoding method, an \( n \times m \) non-redundant data matrix \( A \) consisting of all data vectors of from all families with sequence length \( L \) is constructed. The SVD is then applied to construct an orthogonal basis \( Q_A \) for the column space of \( A \). The rank \( r \) of \( A \) (\( r = \text{rank}(Q_A) \)) and the dimension of the null space of \( A \) are then compared (\( \text{null}(Q_A^T) \)). Using this approach, it is then possible to assess the quantity \( n - \text{null}(Q_A) \) to determine the size of the subspace left uncharacterized by the database. Table 7 summarizes the results. From this table, it is clear that, after redundant encoded vectors are removed, the BLOCKS database thoroughly spans the pattern space. Furthermore, the histogram in Figure 5 further indicates that, while the sequence subspace is well represented, there is also a good degree of separation between the family classes. 5.4.2 Pattern classification Another important database characterization is to examine how the projection method classifies data vectors after the class subspace bases have been constructed using the SVD. Table 7. Characterization of BLOCKS orthogonal complement for various sequence lengths and encodings In a manner similar to Figure 6, we classify all encoded data vectors in order to determine their family membership by applying Equation (26). Figures 7 - 8 show results where the $L = 15$ and $L = 30$ cases have been tested. For the $L = 15$ case, as the vector space dimension decreases more classification errors arise since a reduced encoding will result in more non-unique vectors. The $L = 30$ case leads to longer vectors, hence, it is more robust to reduced encodings. ![Fig. 7. Family classification of each data vector.](image-url) 5.4.3 BLOCKS database search In this section, we demonstrate how to perform database searches using the relevance and reliability equations summarized in Table 6. Database search examples have been reported using the BLOCKS database Henikoff & Henikoff (1994). In this work, we analyze the effect of randomly mutating sequences within the BLOCKS database to analyze family recognition as a function sequence mutation. For the purposes of illustration, we consider a test sequence from the Enolase protein family (BL00164D) in order to examine relevancy and database reliability. For this test sequence with \( L = 15 \), amino acids are randomly changed where the number of positions mutated is gradually increased from 0 to 12. Furthermore, encodings from Table 3 are compared with standard encoding. For this series of tests, the reliability always gives a value of \( \cos(\phi) = 1 \), implying that the randomization test did not result in a vector outside the subspace defined by the database. This corroborates conclusions drawn in Section 5.4.1. Figure 9 shows that the classification remains stable for both encodings until about 5-6 positions out of 15 have been mutated (the family index for the original test sequence is 10). In addition, the relevance can be summarized by computing the difference between the maximum value of \( \cos(\phi_i) \) and the second largest value. For the sake of illustration, if the BLOCKS family with index 10 does not yield the maximum projection, then the relevance difference is assigned a negative value. Figure 10 show the results of this computation. In this test, we observe a consistent decrease in the relevance difference indicating that secondary occurrences are gaining influence against the family class of the test sequence. Fig. 9. Family classification as a function of the number of positions randomized. Fig. 10. Relevance differential as a function of the number of positions randomized. 6. Conclusions This chapter has elaborated upon the application of information retrieval techniques to various computational approaches in bioinformatics such as sequence modeling, clustering, pattern classification and database searching. While extensions to multiple sequence alignment have been alluded to in the literature Couto et al. (2007); Stuart, Moffett & Baker (2002), there is a need to include and model gaps in the approaches proposed in this body of work. Extensions to the vector space methods outlined in this chapter might involve including a new symbol to represent a gap. Regardless of the symbol set employed, it is clear that the approach described can lead to sparse elements embedded in high dimensional vector spaces. While data sets of this kind can be potentially problematic Beyer et al. (1999); Hinneburg et al. (2000); Houle et al. (2010); Steinbach et al. (2003), subspace dimension reduction techniques are derivable from LSI approaches such as the SVD. The IR techniques introduced above are readily applicable in any setting where bioinformatics data (sequence, structural, symbolic, etc) can be encoded. This work has focused primarily on amino acid sequence data; however, given existing structural encoding techniques Bowie et al. (1991); Zhang et al. (2010), future work might be directed toward vector space approaches to structural data. The methods outlined in this chapter allow for novel biologically meaningful weighting schemes, algebraic regular expressions, matrix factorizations for subspace reduction as well as numerical optimization techniques applicable to high dimensional vector spaces. 7. Acknowledgements This work was made possible by funding from grant DHS 2008-ST-062-000011, “Increasing the Pipeline of STEM Majors among Minority Serving Institutions”. The authors would like to thank David J. Schneider of the USDA-ARS for many helpful discussions. 8. References Bioinformatics - Trends and Methodologies is a collection of different views on most recent topics and basic concepts in bioinformatics. This book suits young researchers who seek basic fundamentals of bioinformatic skills such as data mining, data integration, sequence analysis and gene expression analysis as well as scientists who are interested in current research in computational biology and bioinformatics including next generation sequencing, transcriptional analysis and drug design. Because of the rapid development of new technologies in molecular biology, new bioinformatic techniques emerge accordingly to keep the pace of in silico development of life science. This book focuses partly on such new techniques and their applications in biomedical science. These techniques maybe useful in identification of some diseases and cellular disorders and narrow down the number of experiments required for medical diagnostic. How to reference In order to correctly reference this scholarly work, feel free to copy and paste the following:
Mead, Dewey, and Extended Cognition: The Relevance of the Chicago School for Contemporary Cognitive Science Word count: 3396 Author: Roman Madzia (Dept. of Philosophy, Masaryk University, Czech Republic) Email: roman.madzia@mail.muni.cz Abstract: The paper examines views on the nature of cognition by two foremost representatives of the Chicago School of pragmatism – George H. Mead and John Dewey in relation to recent theories and trends in cognitive science such as the extended cognition theory. The paper reconstructs Dewey’s and Mead’s main arguments about the nature of cognition, which (in short) state that cognition is not a matter of creating inner mental representations of the world but rather of creating embodied strategies (habits, attitudes) of negotiating that world directly in action. Next, the author shows how these ideas find an explicit vindication and empirical support within recent research in cognitive science. As a result, in connection to theories of certain philosophers of cognitive science such as Andy Clark, Mark Rowlands and others, the author argues that rather than dismissing the notion of representation altogether, pragmatists should consider its redefinition in terms of practical bodily action. On such an account, we can point out to a certain class of acts which embody the pragmatic notions of habits and attitudes and thus serve as practical ways of negotiating the world. The paper shows that the nature of these acts can do justice to 5 analytical conditions of representation (informational, teleological, decouplability, misrepresentation and combinatorial condition) and yet radically redefine what role the notion of representation should play in the cognitive discourse. In his recent book called *The Pragmatic Turn*, Richard Bernstein writes that a philosopher comes alive and speaks to us from the past when his work becomes a fertile source for dealing with current philosophical problems, when his work can be engaged in novel ways. In what is to follow, I would like to concentrate on the issue of the relationship between the epistemological theories of George H. Mead and John Dewey and some ideas presented recently by the representatives of the strand of cognitive science called the extended mind theory. More specifically, I will focus on what these two schools of thought have to say about the topic of cognition and representation. The main point of this talk is that representation should be defined in terms of action, that is, as a certain way of our active engagement with the world rather than creating inner mental pictures of any kind. Where specifically does cognition stop and action begin? Traditionally, philosophers have tended to think of the relation between perception, cognition, and action in terms of what Susan Hurley once dubbed the “classical sandwich” paradigm of the mind. In her words, “this conception of the mind, widespread across philosophy and empirical sciences of the mind, regards perception as input from world to mind, action as output from mind to world, and cognition as sandwiched between” (2008: 2). In this view, cognition is considered some sort of a central process, taking place in our skulls, which transforms and processes perceptual inputs caused by the contingencies of our environmental surroundings. Action, on the other hand, is usually viewed as some sort of a “servant” to the central cognitive processes, that is, as their mere bodily-instrumental output. At a certain level of analysis the problem of the relation between perception and action can be defined as a problem of the relation between stimulus and response. The main contention of psychological research in times of Dewey and Mead was that, if we are to explain what cognition is, we first have to give an account of the process by which perceptual inputs are transformed into motor action. Everything that happens in between can, supposedly, be called cognition. However reasonable such a position may seem, Dewey’s seminal 1896 paper *The Reflex Arc Concept in Psychology* considers this kind of outlook on the nature of cognition to be deeply misleading. In this paper Dewey executes a thoroughgoing critique of psychological methodologies that have found their goal in the program of establishing causal and nomological relations between stimuli and responses. Within this view, perceptual stimuli are taken to be independent sensory particulars which trigger in the organism cognitive processes that eventually lead to a motor discharge as a consequence of this processing. The crucial problem with such an approach is that it tends to apprehend external stimuli, internal processing, and external response as ontologically independent entities, clearly delimited from one another. Under this analysis, Dewey writes: “The sensory stimulus is one thing, the central activity, standing for the idea is a second, and the motor discharge, standing for the act proper, is a third. As a result, the reflex arc is not a comprehensive, or organic unity, but a patchwork of disjointed parts, a mechanical conjunction of unallied processes” (Dewey 1896: 358). Drawing upon an example of a child seeing a candle introduced first by James in the second chapter of his *Psychology*, Dewey illustrates the practical working of the reflex arc mechanism (see James 1892/1984: 5). The situation is that of a small child that, after seeing a burning candle in her vicinity for the first time, reaches out to its flame and gets burned. The ordinary interpretation of that situation from the viewpoint of the reflex arc theory would hold that the sensory datum of a light serves as a stimulus to the child, leading eventually to the execution of a motor response in the form of trying to grasp the flame. The resulting burn is, subsequently, a stimulus to withdrawing the hand and so on. Dewey argues that the basic defect of such a theory is the idea of the possibility of dividing the unity of human action into ontologically and temporally separated units. Whenever we try to divide experience or action into ontologically distinct pieces, we find ourselves unable to put them back together again. The traditional reflex arc concept, thus, has to be replaced by a new heuristic approach in which the stimulus, the central reaction, and the motor response are taken merely as functional moments of larger organic unity of action. Dewey urged the psychologists of his time to shift their focus from seeing the child as a simple stimulus-response mechanism to an embodied creature situated in an environment, trying to achieve specific goals. That is why in order to understand human action, according to Dewey, we have to start with “larger co-ordination” of the live creature engaging in purposeful action and interacting with its environment. Conscious action always starts as a goal-directed activity that engages the whole organism. According to Dewey, in the process of cognition, perception is not separable from action for it controls the process of action as a purposive behavior from the very beginning until its successful completion. In the process of cognition, therefore, the organism and the world enter into what Andy Clark (2008: 24) has called *continuous reciprocal causation*, which occurs when some system is both continuously affecting and simultaneously being affected by activity in some other system.1 The perceiving organism, therefore, is not a passive recipient of the stimuli but --- 1 In this regard, Joas (1985: 66) remarks: “according to Dewey, unless we make an anticipatory judgment about the action in which stimuli and responses are joined together, we can speak only of a temporal succession and not of the causal relation implied by the stimulus-response model.” actively selects them relative to its goals and interests. From the methodological point of view, Dewey’s pragmatic understanding of action as a value-laden and goal-directed activity necessarily precedes its subsequent functional division into stimuli and responses (1896: 360). In contrast to mainstream philosophy of mind, pragmatists do not take cognition as a capacity on its own but rather as a phenomenon which evolved in order to, as Clark puts it, “make things happen” (1997: 1), to guide action and enable more effective coping with the environment. In short, the mind is an organ for controlling the biological body, rather than a disembodied logical reasoning device. In Deweyan perspective, the basic characteristics of experience understood in terms of skillful attunement to the world and its implicit practical understanding have to be taken into consideration if we want to analyze the organism and its cognitive processes. As Alva Noë once wrote: “perception is not something that happens to us or in us. It is something we do” (2004: 1). If cognition is the kind of thing that can be localized anywhere, according to Mead and Dewey it cannot be situated exclusively in our heads (Mead 1934/1967: 112). In the same manner, Clark currently maintains that “the actual local operations that realize certain forms of human cognizing include inextricable tangles of feedback, feedforward, and feed-around loops: loops that promiscuously criss-cross the boundaries of brain, body, and world. The local mechanisms of mind, if this is correct, are not all in the head. Cognition leaks out into body and world” (Clark 2008: xxviii). George Herbert Mead develops Dewey’s notion of active cognition in his theory of the act. He claims, that in order to explain cognition we can postulate existence of neural events in the central nervous system which sensitize the perceiving organism to certain kind of perceptual stimuli and enable it to act toward them. Mead calls these mental events attitudes, and defines them as beginnings of acts in terms of specific readiness of an organism to perform particular sorts of responses towards perceptual objects. Attitudes are inner, however, “not in the sense of being in another world, a subjective world, but in the sense of being within the organism” (Mead 1934/1967: 5). Attitudes are an integral part of the act although they are not subject to direct observation. On the basis of the organism’s active behavior and problem solving, attitudes come into existence as neural pathways encoding bodily habits which are responding to certain kinds of environmental stimulation. For Mead, the very concept or idea of an object is to be equaled with “such an organization of a great group of nervous elements as will lead to conduct with reference to the objects about us” (ibid.: 70–71). Perception, construed this way, is, from the outset, geared to tracking possibilities for action. Mead’s notion of attitudes means that in perceiving the environment as such a complex of action-possibilities, we create inner states that simultaneously describe partial aspects of the world and prescribe possible actions and interventions with reference to them. Following Dewey, Mead takes the relation between stages of the act as being not primarily causal but rather functional. Functionality, for that matter, presupposes purposiveness. In Mead’s theory of the act, this strand of thought is elaborated in his notion of natural teleology of attitudes. In other words, attitudes play an important role within the act as purposive, goal-directed elements that control certain course of action from the beginning until the very end. Mead says: “If one approaches a distant object he approaches it with reference to what he is going to do when he arrives there. If one approaches a hammer he is musculy ready to seize the handle of the hammer. The later stages of the act are present in the early stages – not simply in the sense that they are all ready to go off, but in the sense that they serve to control the process itself. They determine how we are going to approach the object, and the steps in our early manipulation of it” (1934/1967: 11). Mead’s concept of teleology of attitudes built upon Dewey’s model of organic action as goal-directed activity is currently gaining new credit due to the recent extensive research into mirror neurons. These neurons were accidentally discovered by a group of Italian neuroscientists led by Giacomo Rizzolatti during their research of the ventral premotor cortex in primates which is responsible for grasping and manipulating with objects. Rizzolatti’s group noticed that certain group of neurons fire not only when a primate was executing a certain motor action but, surprisingly, also when one primate was merely watching another primate doing the same thing. What is important for our discussion here is that the mirror neurons are not a new kind of neurons. What Rizzolatti and his colleagues have found, to their own surprise, is that the mirror function is played by the neurons responsible for sensorimotor operations. The findings of Rizzolatti confirm on empirical grounds not only the very intimate connection between perception and action but also the goal-directed nature of individual action. In this respect, findings in mirror neuron research also seem to indicate the existence of attitudes. Analogically to Mead’s example of grasping a hammer, Rizzolatti and Sinigaglia provide their own example with grasping a cup of coffee: “[w]e will grasp it in different ways depending on whether we are picking it up to drink from it, to rinse it, or simply to move it from one place to another. Moreover, our grip on the cup varies according to the circumstances, whether we are afraid of burning our fingers, or the cup is surrounded by other objects; it will also be influenced by our customs, habits, and our inclination to adhere to certain social rules and so on” (2008: 36–37). The present conclusions seem to indicate that Dewey and Mead were right in maintaining that the simple stimulus-response model of action, that is still being advocated (however in somewhat more refined ways), is simply inaccurate a paradigm for explaining the nature of action. The one-dimensional model of having a perceptual stimulus of a cup of coffee → reaching for it → grasping it, etc., is incorrect because in the course of action all these elements work in parallel, the arm moves towards the cup and contemporaneously the hand already assumes the shape necessary for grasping it. The goal of our action is present in it from the very beginning and constantly controls our execution of particular bodily strategies leading to its accomplishment. If we now recall that, in Mead’s view, the concept of object is to be defined in terms of an organization of neural paths that will lead us to certain kind of conduct with reference to that object, we can see why he calls distant perceptual objects *invitations to action* (Mead 1938: 12). Cognizing organisms are thus not to be understood as disembodied computing engines, but rather as cognitive agents, situated in environments in which they pursue their practical goals on the basis of what James J. Gibson called *affordances*. According to Gibson: “affordances of the environment are what it offers the animal, what it provides or furnishes.” (1979: 127). Affordances are possibilities for use, intervention, and action offered by the local environment to a specific type of embodied agent. In this respect, a comparative psychologist Louise Barrett (2011: 98) makes an insightful point: “Affordances are ‘organism-dependent’ … because they reflect the degree to which an animal with a particular kind of nervous system can detect and make use of particular kinds of environmental opportunities.” For example, a human perceives a chair as affording sitting, but the affordances presented by a chair to a hamster would be radically different. From the point of view of the argument I am endorsing here, Mead’s crucial concept of attitudes elaborated in light of Dewey’s abovementioned 1896 article enables us to redefine the notion of representation on pragmatic grounds. As we have seen, attitudes are outcomes of adaptive strategies of higher-order organisms. These attitudes take the form of neural pathways enabling the organism to accurately respond to certain perceptual stimuli in the course of their goal-directed action. They enable the organism to trigger adequate habitual responses in the presence of the stimuli that may lead them to fulfillment of their pragmatic goals. If, on the one hand, there is no ontological gap between an organism and the environment and, on the other, attitudes and habits are formed as the cognitive agent’s action-maps of the environment itself, then we no longer have to think of representations in terms of creating models of an external reality. Rather, we should understand them as models of interaction with it. Cognitive agents do not have to create rich inner models of the world, instead they can, in words of the roboticist Rodney Brooks “use the world as its own model” (1991: 1). Such a view of representation as creating models of interaction resonates also with Charles S. Peirce’s words (1931-1966: 6.95): “we have direct experience of things in themselves. Nothing can be more completely false than that we can experience only our own ideas.” Following Mark Rowlands (2006: 95), I propose that the kind of human actions that embody attitudes and habits could be called deeds. From the pragmatic perspective, deeds could be defined as bodily expressions of attitudes that, with time, slip under the threshold of personal-level consciousness and become pure habitual reactions to certain environmental stimuli in the course of our goal-directed intentional actions. To use Rowlands’ example, deeds include such things as the positioning of fingers in catching a ball that is flying toward us, or the movement of our fingers while playing the piano. They work at sub-personal level of consciousness and as models of interaction with the environmental structures they attune us to the world. Deeds are pre-intentional acts – we usually do not think about them in our everyday experience, and yet, as expressions of habits they effectively map appropriate worldly structures and enable us to achieve our pragmatic goals. We employ them in accurate positioning of our legs when walking the stairs, spontaneous motor operations when driving a car etc. With Michael Wheeler, we can call deeds “action-oriented representations” (2005: 197). Deeds as expressions of attitudes and habits re-present the pre-existing world not as an internal image but as a virtual space of action. What is represented by means of deeds is not knowledge that the environment is so and so, but knowledge of how to negotiate the environment. In the action-oriented approach, says Wheeler, “how the world is is itself encoded in terms of possibilities for action” (ibid.). According to the pragmatists, mind and nature are, ultimately, the same thing, which means that in the process of cognition the mind engages the environmental structures and reaches out into the world: As Mead once remarked, “we can approach the noumenal nature of reality only through the noumenal nature of thought ... the --- 2 According to Rowlands, the human action can be divided into three basic kinds. Deeds occupy the logical space between what Rowlands calls actions (which are intentional courses of action perceived and carried out on the personal level of consciousness) and doings (non-intentional movements, of which we are not aware and which serve no purpose connected with action). See Rowlands (2006: 93-111). experience in which human beings are involved, is the constituent part of reality which they judge“ (Mead 1929/1964: 339). If cognition functions within the brain-body-world nexus, the problem of how our representations match up with the world does not even come up. To paraphrase James’ example, deeds represent the appropriate worldly structures in a similar way as the shape of a key matches with a particular lock. Neither the lock, nor the key, can by themselves open the door; they can do it only in conjunction with one another. Representation is not primarily a noun. Rather, we should understand it first and foremost as a verb. Deeds represent the world not in terms of creating inner mental pictures of it but by directly engaging it in our action. It could be, therefore, maintained that deeds represent the appropriate environmental structures if we can achieve our particular goals by means of enacting them in our action. On this background, we can also maintain that deeds are able to satisfy the analytic criteria commonly regarded as necessary and sufficient for an item to qualify as representational. According to Rowlands (2006: 114), there are, it is generally accepted, five such criteria: 1) **Informational condition** – an item $r$ qualifies as a representational item only if it carries information about some state of affairs $s$ that is extrinsic to it. 2) **Teleological condition** – an item $r$ qualifies as representational only if it has the proper function either of tracking the feature or state of affairs $s$ that produces it, or of enabling an organism to achieve some goal in virtue of tracking $s$. 3) **Decouplability condition** – Item $r$ qualifies as representing state of affairs $s$ only if $r$ is, in an appropriate sense, decouplable from $s$. 4) **Misrepresentation condition** – item $r$ qualifies as representing state of affairs $s$ only if it is capable of misrepresenting $s$. 5) **Combinatorial condition** – for an item $r$ to qualify as representational, it must occur not in isolation but only as part of a more general representational framework. From the pragmatist perspective, if the concept of representation has any content at all, it is precisely the above-mentioned one. If we should illustrate what such a representation through action looks like in practice, let us imagine the following scenario. I enter into a dark room and hit the switch of the lights. If the lights go on, then we can determine whether the deed of hitting the switch counts as representational of certain features of my environment on the basis of the above-listed conditions. The deed of hitting the switch counts as representational because, under the informational condition it, e.g. tracks the location, shape and size of the switch. The deed is teleological because it has the proper function of achieving a practical goal in virtue of tracking the environmental state of affairs. The deed is decouplable from the state of affairs it tracks because I can later remember and demonstrate how I hit the switch replicating the same act. In the process of representation through action, I can misrepresent my environment in many ways. Eventually, the deed in question can be combined into a more general representational structure (by means of hitting the switch I try to pursue some further goals – finding a book etc.). In this, quite minimalistic account, successful employment of deeds in the world means that they are correct representations of the appropriate environmental structures since they stand the test of practical action. This is not to mean that they represent the world in terms of accurate copying it, but rather in terms of accurate coping with it. Pragmatism, as I maintain, does not necessarily have to get rid of the notion of representation altogether but, rather, redefine it in such a way so as to put it back in the world where it actually belongs. References:
"The Only True People" LeCount, Lisa J., Beyette, Bethany J. Published by University Press of Colorado LeCount, Lisa J. and Bethany J. Beyette. "The Only True People": Linking Maya Identities Past and Present. For additional information about this book https://muse.jhu.edu/book/50019 Part I Maya Identities of the Present and the Ethnographic Past I visited the Yucatán Peninsula during the summer of 2007 for the first time in over two decades and for the first time since I began doing formal ethnographic work in highland Guatemala in the mid-1990s. I was there mostly as a tourist, hoping to meet my daughter for a few days as she ended an environmental course on the peninsula, and then I stayed for two weeks trying to get a better sense of how people are dealing with cultural and economic changes in the region, as well as a sense of what it means to be Maya among the lowland Yukatek population whose language and culture are often referred to simply as “Maya.” This was not formal research, but some of the cursory differences from Guatemala, where I have been working for the past twenty years, were startling. The sense of openness in movement was a relief after my experience in an increasingly gated Guatemala City, where the population continues to struggle with the increase in violence nearly two decades after the end of the civil conflict there. At the same time, this apparent openness also took other forms—women in shorts, for example, driving motorcycles as the preferred mode of transportation in places like Ticul on the edge of the Puuc region south of Mérida. Although I sometimes found evidence of political or social organizations among the local Maya population—and near the Loltun Caverns I even picked up a self-published book by a local scholar, apellido Xiu, on Maya views of death—the closest I came to an obvious public political statement directed toward indigenous concerns was on a mural outside the Casa de la Cultura in the plaza of Felipe Carrillo Puerto (see figure 2.1). Depicting a Maya person emerging from an ear of corn with a pyramid in the background and with various Maya glyphs and numbers setting the iconographic context for this emergence, the mural bore the words “La Zona Maya No Es Un Museo Etnográfico Es Un Pueblo En Marcha” (The Maya Zone Is Not an Ethnographic Museum; It Is a People on the Move). Reflecting on those words now, from the perspective of visual and symbolic ethnography, they clearly resonate with my field experiences observing ethnic organizing in the context of the Maya Movement in Guatemala. Often referenced outside of Guatemala as a pan-Maya movement driven by the impetus of uniting all Maya peoples (pueblos) within a common sense of Maya identity, the movement begins by “reappropriating (from Western academia) and reinterpreting (from an indigenous perspective) research on the ancient and modern Maya” (Fischer 1996:64). Nevertheless, in practice, some tension remains between this overarching Maya identity and the local identities affirmed by people who continue to claim affiliation with their language group or community (municipio) of residence. Moreover, while at its broadest extent a pan-Maya identity would indeed cross national boundaries to include all Mayan speakers in Mesoamerica, I suspect that the sentiment of “this” people on the move, like identity more generally, is more rooted in place. Place here is circumscribed by the local context of the Caribbean coast of the Mexican state of Quintana Roo, a place that is also home to the sanctuary of the Talking Cross and a site of ethnic resistance and independence during the Caste War—with both the symbol and the resistance enduring from the mid-nineteenth century. Although the reference to the “Zona Maya” could refer to the larger Mesoamerican region where the Maya live and the Ruta Maya has developed in fits and starts to foment economic, cultural, and tourist interaction in the region, it can probably best be interpreted as an embracing of the independent spirit of the Maya—Yukatek—ancestors who participated in the Caste War. The resistance to exoticization, as if the Maya were pieces in a museum, is surely a statement in response to the sheer volume of tourism in the area—both in the beach resort corridor in Quintana Roo and in the appropriation of the archaeological sites throughout the peninsula in the context of the Mexican government’s policy of indigenismo, which focused on giving attention to Mexico’s prehistoric indigenous heritage while continuing to promote the assimilation of indigenous peoples into mestizo Mexico. Such resistance is far from the only narrative of engagement with the rapid social change on the peninsula since the 1980s, but it provides a frame of reference and a point of comparison with the cultural emphasis on Maya identity in the Guatemalan highlands. I begin with this extended vignette because there has been some call for more comparative study of indigenous culture across national boundaries in Mesoamerica (Watanabe and Fischer 2004), and because the multidisciplinary perspective in which this volume is grounded can benefit from consideration of ethnic organizing. in Guatemala, as it has become more trenchant in the post-conflict years. As noted, in various contexts, the ethnogenesis of “the Maya” in Guatemala has been referred to as a movement for Maya nationalism and as a pan-Maya movement that crosses boundaries and seeks to unite in a broad historical and cultural framework perhaps as many as 6 million to 8 million people who continue to speak twenty-eight different languages and who share a cultural tradition rooted in common language origins, cosmology, and lifeways in southern Mexico, Guatemala, and parts of Belize and Honduras. As one attempt describes the nature of the movement, “To look for the unity of the Maya People has been one of the principal ideals of the Maya Movement in Guatemala. A political and ideological mobilization has been established around this ideal that has appealed to ties of common cultural experience among the indigenous population—a shared past and a collective destiny” (Cumes 2007:86, original emphasis). The movement burst onto the Guatemalan political scene in the late 1980s and early 1990s as the thirty-year civil conflict wound down, and the trappings of formal democracy were restored on the way to a peace accord that definitively ended the war in 1996. One of the earliest published articles on the movement (Smith 1991) was written for the North American Council on Latin America (NACLA); by the time the Kaqchikel Presbyterian executive of the Hermandad de Presbiterios Mayas wrote for the same publication in 1996, it was claimed that there were over 300 organizations with Maya constituencies (Otzoy 1996). By the end of the conflict, the movement seemed well poised to push for a “multiethnic, pluricultural, and multilingual” state that was the articulated goal of a number of organizations within the movement. This momentum, along with the awarding of the Nobel Peace Prize to Rigoberta Menchú in 1992, was emblematic of the rise of Maya identity and the confluence of social movements directed toward the fomenting of ethnic identity and culture as well as toward pushing for the realization of a peace that would end Guatemala’s conflict. The Maya also had an intelligentsia that promoted its agenda both within Guatemalan social and political arenas and among academics in an international context, as well as sometimes through elements of the global human rights community that took an interest in Guatemalan affairs. The most visible spokesperson in articulating the Maya nationalist agenda has been Demetrio Cojtí Cuxil, who served as vice minister of education during the administration of Alfonso Portillo (2000–2004) and whose latest book is titled New Perspectives for the Construction of the Multinational State: Proposals to Overcome the Non-Fulfillment of the Accord on the Identity and Rights of the Indigenous Peoples (Waqi’ Q’anil Demetrio Cojtí, Son Chonay, and Guaján 2007). The title references the side agreement on indigenous affairs that was negotiated as part of the peace process and finally concluded by the negotiating parties in 1995, but the proposal continues to push for the creation of a truly multiethnic state. In many ways, the title of the latter work illustrates the force of the Maya Movement in strictly political terms. Although some have argued that Menchú has never been totally accepted by the Maya community as a whole, her seventh-place showing as the presidential candidate for the Encuentro por Guatemala coalition during the 2007 campaign with a total of 101,316 votes (3.09%) puts an exclamation point on the political force of Maya organizing in the national electoral arena at the present time. These results should not overshadow the historic fact of an indigenous woman running for president of Guatemala. At the same time, the comments of the report of the European Union observer commission for the 2007 elections in regard to Menchú’s candidacy raise skepticism regarding the possibility of a Maya voting bloc (or perhaps even a Maya political party) in the near future: “The electoral failure of her candidature, which is obviously due to several different factors, seems to underline the fact that at the moment in Guatemala, the conscious indigenous vote is far from being a relevant force” (European Union 2007:48). Nevertheless, some of the salient issues of ethnogenesis and ethnic identity are brought to the fore in a brief comparison of the context of Maya organizing in Guatemala and in Mexico. In commentary on a series of articles dealing with Maya identity in the Yucatán Peninsula in the *Journal of Latin American Anthropology*, Ueli Hostettler makes these observations regarding Maya identity on the peninsula when refracted in the light of Guatemala’s Maya Movement: > By problematizing the “Maya” label, these articles reject an essential approach to ethnicity in the peninsula . . . On the other hand, while they concur in problematizing the history of Maya identity . . . the authors only indirectly address the fact that in the larger Maya area, especially in Guatemala, the term “Maya” and related issues of “Mayanness” have gone “public” and left the academic setting to become one of the mainstays of the Pan-Maya Movement. All political implications of anti-essentialism aside (Warren 1998), it seems that over the last decades a new Maya identity was born in Guatemala which makes deliberate use of the symbolic capital related to the complex and controversial image of the “Maya.” (Hostettler 2004:193) Two issues stand out in Hostettler’s commentary. First, there is a differential appropriation of Maya identity in Mexico and Guatemala. While somewhat outside the scope of this chapter, I suggest that some of the difference can be attributed to the relationship of the state to indigenous populations. For a host of reasons, the Maya population in Mexico did not experience the kind of genocidal war experienced by the Maya in Guatemala. Both the legacy of the Mexican Revolution in constituting the state and the character of Mexican *indigenismo* in relation to the state are relevant to this issue, as is the manner in which the state dealt with agrarian concerns in the post-revolutionary period. In the Mexican highlands (in contrast to the Yucatán Peninsula), the Zapatista uprising coincided with the formal implementation of the North American Free Trade Agreement (NAFTA) in 1994, and this was on the heels of the Salinas administration’s attack on the foundations of historical agrarian policy when it amended Article 27 of the constitution in 1992, thus privatizing ejido land in the context of other changes. While Zapatismo continues to receive scrutiny from a number of directions, including attention drawn to local-level democratization in the context of pluralistic ethnic communities, the movement has not translated into the same kind of engagement with the Mexican state by the Maya population—as Maya—that has been the case in Guatemala. The success of engagement with the state seems open to question in both highland Chiapas and Guatemala, and the issue of autonomy will figure to some degree in how one might gauge the success of the Maya or a more broadly construed indigenous agenda in the context of either nation. June Nash, in one of the few comparative articles dealing with Maya organizing and the issue of autonomy, argues that so far “Maya have not strengthened their ties with their Maya neighbors across the border. We do not see the fertile exchanges possibly because the governments on both sides have precluded this possibility” (Nash 2004:196). Second, although issues of indigenous and collective rights require more scrutiny from a number of angles, in the particular case of Guatemala, Richard Adams’s early commentary on the Guatemala context situates the Maya movement squarely within a framework of ethnogenesis: The Maya intelligentsia in Guatemala has been very successful in the promotion of the use of the term “Maya” for all of the indigenous people of Guatemala. The objective is to provide a stronger group solidarity to those that before were known as “indios” or “indígenas.” The term “Maya” is, in fact, constantly arising as a general term for the Guatemalan indigenous population. The consequence of this is that the Mayas of Guatemala triumphed in the invention of a new ethnic group: the Maya, who did not exist in 1950 but who many acknowledge exist in the present, which should be considered a happening of evolutionary significance. (Adams 1995:410, my translation) Matthew Restall’s article on Maya ethnogenesis puts an exclamation point on Adams’s interpretation of the historical significance of the “invention” of the Maya. With a particular focus on the lack of a Maya identity in the Colonial period, he writes of an “invented ancient Maya identity (hence the current Maya ‘revival,’ ‘renaissance,’ and ‘resurgence’)” and of “three or four centuries of ‘Maya’ history during which Maya peoples refused to accept categories of identity assigned to them, be it indio or Maya. In a sense, then, the Maya struggled for centuries in the face of steady opposition against their own ethnogenesis” (Restall 2004:82, original emphasis). The recognition of a pan-Maya identity that crosses national and linguistic boundaries contrasts with perceptions of identity-in-place bound to kinship or village groups with shared lifeways and worldviews in both pre-contact and Colonial Mesoamerica. Such recognition clearly entails a constructivist perspective, although it does not address activist essentialism that has become much discussed in terms of the way the larger movement has appropriated cultural traits and the cosmovision of the “ancient Maya” and projected them into the public sphere in support of its pan-Maya agenda. Essentialism is fairly well-trodden ground at this juncture, but it is useful to note the dialectical way the term can be used depending upon who is doing the essentializing. Jon Schackt notes that “‘the invention of the Maya’ could be attributed to Maya scholarship: the archaeologists, anthropologists, etc. who started to use this label for cultural horizons and continuities that interested them. Some of their numbers implicitly ascribe to these continuities an imagined Mayan essence transcending history” (Schackt 2001:11). BEYOND ETHNOGENESIS The argument underlying this chapter is that issues of ethnogenesis are probably less important at this point in time than is continued consideration of how indigenous peoples negotiate their multiple identities within the framework of personal experience while in some cases projecting a unified identity in the political arena. Although I ran across at least two references to multiple identities in recent literature on ethnicity in Mesoamerica, I first remember hearing the term in a conversation with Kaqchikel Maya anthropologist Alberto Esquit Choy when we were graduate school colleagues several years ago. Alberto’s family had been affected by la violencia in Patzicía during the war, and he had coauthored a book on the Maya Movement (Gálvez Borrell and Esquit Choy 1997). I was working on a project dealing with evangelical participation (or not) in the process of consolidating democracy in Guatemala around the turn of the millennium. A larger issue for me at the time was how to frame pan-Mayanism, on the one hand, while asking how it is possible to be both Maya and Protestant on the other. What struck me in the field, beginning in 1997 and in some ways continuing to the present, was the frequent disjuncture between the passion surrounding Maya activism in the capital in certain forums designed to foment Maya identity and how little in some ways the Maya Movement seemed to have permeated the fabric of the municipio and the local historical Protestant community where I had done my work in the western part of the department of Quetzaltenango. There were a number of Maya organizations as well as non-government organizations (NGOs) active in the region, so it was not a case of total disassociation unless I asked a question, for example, about Maya priests or spiritual guides. Among evangelicals I received the almost inevitable response, “Oh, you mean brujos.” While the tone sounds dismissive, further investigation revealed considerable certainty that indeed the shamans had power that was counterposed to new power encountered in the person of Jesus, brought initially by the Protestant missionaries. Beyond the immediate issues of conversion and the implications of conversation for identity formation, national political (and therefore cultural) agendas did not loom as large on the horizon of the people with whom I worked. Moreover, even among those who did dedicate themselves to social concerns in terms of pro-community activities or the informal investigation of their indigenous identity and costumbre, there was wariness about the new openness immediately after the signing of the peace accord. “Things can change,” one person told me on several occasions. Some of this wariness has to do with the rural-urban split in Guatemala that frequently shapes social and political perspectives in profound ways. One example can be seen in terms of access to information in rural communities. San Juan Ostuncalco, the municipio where I conducted the majority of my field research, is only seven miles from Guatemala’s second city, Quetzaltenango, but in the late 1990s one could rarely buy a newspaper after noon on a weekday. Even so, in terms of what the media offered during those times of social ferment, supplements to the regular paper were published on a rotating basis in Mam, Kaqchikel, and K’iche’. The offerings reflected the momentum, if not the actual power, of the Maya Movement at that time, and the situation with the print media in the far western highlands today appears less bilingual in many ways than it was at the end of the 1990s. My own areas of research are grounded in the shifting religious landscape of Guatemala and how that shifting panorama articulates with religion writ large in Latin America and with the political landscape in social and ethnic renewal movements. The nexus, then, is one of religion, ethnicity, politics, and social change in a post-conflict situation. The processes of identity formation in the parallel frames of religion and ethnicity raise the issue of how the ethnography of religion contributes to contemporary understandings of Mayaness—in place and in transnational contexts. Immigrants to the United States, for example, provide satellite video of a patron saint’s fiesta in Florida for the consumption of the home community in the department of Huehuetenango (Steigenga 2006). Being neither an archaeologist nor an ethnohistorian, I have tended to focus my attention on processes of ethnic renewal, which take into account both individual and collective sense(s) of identity formation and the constraining and adaptive aspects of culture perhaps best articulated in Sherry Ortner’s (2006) version of practice theory. Renewal here entails an emphasis on the processual nature of identity construction when a movement defines its identity in relation to other groups. Joane Nagel’s emphasis on ethnic renewal is rooted in a constructivist view of culture and is a reflection of how “cultural constructions assist in the construction of community when they act to define the boundaries of collective identity, establish membership criteria, generate a shared symbolic vocabulary, and define a common purpose. Cultural constructions promote collective mobilization when they serve as a basis for group solidarity, combine into symbolic systems for defining grievances and setting agendas for collective action, and provide a blueprint or repertoire of tactics” (Nagel 1994:163; cf. Nagel 1996). Ultimately, this perspective provides a more complete framework for considering ethnicity and the possibility of ethnogenesis in Mesoamerica than does the essentialist-constructivist terminology we have been using most recently or the substantivist-instrumental terminology Clifford Geertz (1973) and others were using forty years ago. In describing her own engagement with practice coming out of a concern with feminism, Ortner found the theory compelling in that it “provid[ed] a dialectical synthesis of the opposition between ‘structure’ (or the social world as constituted) and ‘agency’ (or the interested practices of real people) that had not previously been achieved. Moreover, the idea that the world is ‘made’—in a very extended and complex sense, of course—through the actions of ordinary people also meant that it could be unmade and remade” (Ortner 2006:16–17). This space of practice is the place where both Maya Movement activists and individuals trying to make sense of their own identity in place engage the *costumbre* handed down by the ancestors and may find themselves differentially engaged in processes directed toward the *reivindicación* of Maya identity. In terms of agency, the issue here is the scale at which people are engaged with political processes involving such *reivindicación*. Are they focused more on the local context and the quotidian activities surrounding community life and subsistence, or do they begin with the more expansive national or transnational context, where the frame of activity involves dialogue even with those who today might insist that they maintain a cosmopolitan perspective on place and identity? **RELIGIOUS PRACTICE, PLURALISM, AND IDENTITY** In certain regards, religion as such received rather less attention than I envisioned when I first became involved with the panel out of which this volume has come. Because much of my work is done with evangelicals, I have reflected for several years on Alan Sandstrom’s comment about how Protestantism in Mexico (and by extension in Mesoamerica) can be conceived of as a “third ethnicity.” Protestantism in these contexts surely fits the framework of ethnogenesis: With people’s choices defined by the Indian-Mestizo divide, there was little room for radical change in ethnic identity. The Protestant missionaries probably unknowingly provided a third alternative for people experiencing the collapse of the old colonial arrangements and growing influence of the new economic order. Instead of choosing between Indian and Mestizo, they could now become hermanos. Converts to Protestantism are neither Indians nor Mestizos but instead form a third ethnic group that sidesteps the traditional social hierarchy with its roots in the colonial past. Members of this new group see themselves as dynamic, progressive, and closely affiliated with the prestige of the United States and its perceived technological and economic superiority. (Sandstrom 2001:277–78) If Sandstrom is correct, the argument can be made that we have actually witnessed not one but two ethnic movements in Mesoamerica over the past three decades. Moreover, both pan-Mayanism and the advent of Protestantism can be situated within the context of rapid social change indexed in Latin America by post-Colonial global movements of indigenous activism and the oft-noted shift in the center of gravity of Christianity to the global South. Nevertheless, given the pluralism of Protestantisms in Latin America, I suspect that Sandstrom’s observation holds true more at the community level than at larger scales of analysis. In framing the issue at the community level, I am suggesting that practice approaches linking structure and agency are more useful in examining the interplay of religious and ethnic identity than are more rigid notions of ethnogenesis, although both optics are useful for understanding identity construction in place and across borders in the Americas. While identity in pre-contact and Colonial Mesoamerica is typically understood to be rooted in particular places and communities, indigenous or Maya Protestant “ethnicity” itself fragments into disparate groups that have differential valences with Mayaness, the larger evangelical community, and the nation-state. Maya evangelicals continue to identify with their language and cultural communities even as they also identify with particular denominations or more broadly conceived religious currents such as Pentecostalism. In this view, in Guatemala and probably in Chiapas and the Yucatán region across the border as well, it is not a coincidence that evangelical religions gained traction and began significant growth only in the 1960s. Henri Gooren reports that in 1960 Guatemala was 5 percent Protestant; that number had grown to 7 percent by 1976 (Gooren 2001:183) and to at least 25 percent by 2001 (Grossman 2002:128). From another perspective, conversion viewed from the local rather than the aggregate level can be seen as a process that simultaneously involves identity formation and the segmenting of identity. Geoffrey Braswell attributes the historical evidence for the Nahualization of K’iche’ elite culture in the decades prior to contact in Guatemala to a “pragmatic adaptive strategy” related in part to the development of classes within K’iche’ society and in part to instrumental concerns about the presence of Nahua speakers in close vicinity in the Xoconochco (Soconusco) region along the Pacific Coast (Braswell 2003:303). To be sure, Maya Protestantism represents a different kind of adaptation embodying simultaneously identification with lo maya and the potential for the fragmentation of what it means to be Maya within both the individual person and the community as a whole. These dual potentialities are both in evidence when the Biblical Society of Guatemala releases a new translation of the Bible in the Q’eqchi’ language or when a Pentecostal congregation in an aldea of Ostuncalco with 9,000 inhabitants has 800 adherents. This aldea is also one in which local shamans are said to have burned the house of Presbyterian missionaries in the 1930s, yet the Mam language predominates in the community and the women, at least, have not given up their distinctive dress as a marker of identity. Such Pentecostal congregations also sometimes provide room for women prophets and pastors, even if they do not address social development issues within local communities. I suggest that this points to a process of the reconstruction of identity at the community level, and it remains to be seen how this reconstruction will be projected into larger spatial frameworks such as that of the municipio, which in its entirely is over 80 percent Mam speaking. It is worth noting that the alcalde between 2004 and 2008 was a Catholic from the same aldea. One might even argue that in the long term, conversion also represents a process wherein costumbre is traded for a new costumbre, the shape of which projects a Maya identity of unknown character into the precarious future that is Guatemala’s destiny. Such a new costumbre may well incorporate new content in terms of both cosmovision and practice, but it will also reflect continuity with lifeways associated with Maya communities and local ways of adapting to outside influence evident in the Maya cultural tradition for at least two millennia. As in the past, this mode of adaptation will articulate multiple agendas in other frames of reference that remain under negotiation. The nature of Maya identity in the congregation mentioned above surely contrasts with the sense of identity articulated in June 1996, when Presbyterians in the Kaqchikel Presbytery of the National Evangelical Presbyterian Church memorialized Manuel Saquic, their assassinated colleague and director of the presbytery’s human rights office, as a triple martyr—a Maya and a Christian (in the ecumenical sense) dedicated to human rights (Samson 2007:104–7). The ambiguity of these identity struggles in light of larger processes of identity formation can be seen in this excerpt from an interview with a Maya Presbyterian minister. He is literate, with almost a high school education, and he has a long history of activism as a catechist and a member of pro–community service committees in the largely Mam municipio of San Juan Ostuncalco. My question had to do with what being Maya or even Mam meant to him: Well if we speak [of] Mam, we understand that we are a group or tribe of the Maya people, descendants of the Maya . . . Some say that we don’t come from the Maya, as if we came with the Maya. Now they say we are descendants of the Maya. So there isn’t a version or exact information. But as Mams we feel that, yes, we are Maya, we are descendants of the Maya people, and we are from the Mam tribe . . . We feel that, yes, we are an authentic and native (genuino y natural) people from Guatemala, a Maya people. And also, we feel that [our culture] is a treasure. We are not ashamed of being Mams; on the contrary, we are proud to speak in our . . . own language; and now our women dress in their own style of clothes. [It’s] not like before when there was shame in front of the Ladinos, because they say we are indios, compared us to pigs—dirty, useless. Because the word indio means useless, he doesn’t know anything. But on the contrary, I am not ashamed to speak my language before the Ladinos. It is my mother language; it is an inheritance from our ancestors. But I am Mam as well; I am proud to be Mam, to be authentic and native from Guatemala. **CONCLUSION** This returns us to the image of the Maya as a pueblo en marcha. Responding to pluralism in the arena of the continuing construction of ethnic identity—and in the somewhat more restricted frame of religious practice—demands a move beyond conceptualizations of ethnicity solely defined by the practice of a unified costumbre that shapes personal and collective identity through the generations. Even so, contemporary formulations of pluralism begin for many in a sense of participation growing out of an enduring identity in continuity with the past. In Mesoamerica, such formulations of ethnicity have the potential to articulate profound political and social challenges to the legitimacy of nation-states founded on constructs of mestizaje or indigenismo that continue to marginalize indigenous peoples in discourses about the nature of citizenship and the state. More sophisticated affirmations of pluralism move us into the realm of embracing difference within the context of common projects; when it comes to nation building and reconciliation in post-conflict Guatemala, the character of the state itself is brought under scrutiny by the process of Maya ethnic renewal. Maya religious practices will continue to be a key aspect of the definition of Mayanness and the construction of ethnicity on the Guatemalan national stage. I attended a book presentation in a downtown hotel in Guatemala City during the summer field season of 2007. Admittedly, it was held in Zone 1 and not in the swank hotels of Zones 9 and 10 of the city’s “Zona Viva.” Nevertheless, it was attended by 75 to 100 people, mostly Maya, as the book dealt with political parties in the national elections and their stance in regard to Maya issues, specifically Maya women (Ochoa and Garoz 2007). It was also an educational event, with a lively presentation on the book, commentary from two critics, and questions from the audience. I was handed a program as I entered the room where the event was held, and I saw that the assembled were turning in the four directions as a Maya spiritual guide (a priestess in this case) lit candles and opened the event. The invocation was listed as part of the program, and after nearly an hour and a half of presentations, with everyone ready for food, the “closing of the invocation” took place. It was rather hurried but surprisingly ecumenical in nature and tone, much like a hasty benediction when the 11:00 Sunday church service has gone ten minutes too long. As I left, I wondered about North American battles over the separation of church and state and how the pluralism of religious practices in Guatemala will shape the march of Maya identity and Guatemalan-ness in both time and transnational space in the years to come. It seems clear that governments in Mesoamerica will continue to resist agendas related to the autonomy and collective rights of indigenous peoples even as activists pursue a variety of agendas that will span the spectrum from the ostensibly cultural to the overtly political. The invocation at the book signing demonstrates the increased focus on religion or cosmology as a central aspect of ethnic identity and points to culture as a point of contestation as the Maya deal with multiple or multifaceted identities (LeCount, this volume) tied to local, national, and transnational spaces into the future. For the past, ethnohistorical and archaeological evidence reveals instances of pan-regional identity undergirding the legitimation of elite power in various contexts throughout Mesoamerica (cf. Carmack 1968; Ringle 2004). Although interpreting the record remains an ongoing process, the legitimizing forces of mythology and cosmology strengthen identity construction in the present. The Maya Movement itself often has a different valence depending on whether the reference is to Maya nationalism in a multi- or pluricultural society or to Maya identity at the local level. In fact, defining Maya culture or identity is complicated at the community level, where purity of “Maya” practice might be less of a problem than at the level of those involved in the creation of a national ideology rooted to some degree in opposition to the culture of “the Other.” In pragmatic and political terms, what takes place beyond the community, such as transnational migration or the shaping of government policy in regard to cultural issues like bilingual education or respect for sacred places on the landscape as facets of collective or cultural rights, will also have a bearing on whether identity is reinforced or contested in various spatial frames. Meanwhile, ethnographers and archaeologists alike will gain a better understanding of the shape of identity in Mesoamerica in the past precisely to the extent that we dedicate ourselves to a clearer reading of the movements of Maya peoples in the present. ACKNOWLEDGMENTS I thank Grant Jones for reading and making comments on the version of this chapter that was presented at the 2006 meeting of the American Anthropological Association, as well as for ceding me the opportunity to make a presentation on the panel in the first instance. I am also grateful to Bill Ringle for his continuing efforts in helping me think through some of the ways contemporary social and political activity in Mesoamerica is reflected in the past. Kate O’Connor, a recent Davidson College graduate, helped with some of the final edits. NOTES 1. Xiu was the name of the dominant lineage near Mani at the time of the Spanish incursion (Clendinnen 1987:25). 2. As a colleague notes, the east coast of the peninsula is known as the Maya Riviera in tourist circles. 3. On the use of “cultural tradition” for Mesoamerica, see Carmack, Gasco, and Gossen (2007:5–6). I also continue to be informed by conceptualizations such as that of a Maya cultural region for the place inhabited by contemporary Maya populations in both lowland and highland areas. This perspective is not meant to deny differences between different regions, differences that can also be indexed by the lowland-highland dichotomy and that are reflected in cosmology as well. 4. It is significant that the rural and indigenous population carried center-left candidate Álvaro Colom to victory in the runoff election with Otto Pérez Molina, a retired army general. Colom won in twenty of Guatemala’s twenty-two departments, the first time a candidate won the presidency without carrying Guatemala City since the formal return to democracy in the mid-1980s. This is also pertinent to differential ethnic organizing in rural and urban areas, mentioned below. See the analysis in European Union Election Observation Mission, Guatemala (European Union 2007:59) and the transcript of the interview with Guatemalan author Francisco Goldman on the Democracy Now website (http://www.democracynow.org/2007/11/6/guatemalas_indigenous_countryside_drives_election_victory; accessed October 27, 2009). According to Guatemala’s Supreme Electoral Commission, Menchú, who ran on a left-wing coalition ticket, received 145,080 votes in the 2001 presidential election; that was 2.87 percent of the vote (TSE 2012:156). None of my commentary here should be taken as ignoring the fragmentation of Guatemalan party politics or the difficulties of forming leftist coalitions in Guatemala and much of Latin America (see Samson 2012). 5. In Guatemala, the Accord on the Right and Identity of Indigenous Peoples has never been ratified by the congress, despite having been approved by the government and guerrilla negotiators in 1995. Likewise, the San Andrés Accords negotiated between the Mexican government and the Zapatista National Liberation Party (EZLN) in late 1995 and 1996 represented a push for both autonomy and Indian rights, but it has also not been acted upon by the Mexican congress (Womack 1999:304–15; Aubrey 2003; Esteva 2003). 6. Other reasons for the divergent trajectories include the geography and the multiplicity of languages spoken in the region. The Maya on the peninsula in Mexico are also separated by long distances from the central power of the Federal District and by their own history of separatism and resistance. In addition, the more diverse indigenous population in Mexico complicates efforts at pan-indigenous organizing in a way not experienced in Guatemala, despite the insistence that the government acknowledge the rights of the Maya, Garífuna, and Xinca peoples (Bill Ringle, personal communication, 2008). 7. While I agree with the general idea here, I am less comfortable with the notion of the invention of an ancient identity. The process seems more dialectical to me, although that is surely a space for debate among ethnohistorians, archaeologists, and ethnographers. This is one of the reasons I emphasize the notion of ethnic renewal (cf. chapter 5, this volume). 8. Schackt’s take on the issue of authenticity is that “a person’s ethnic identity is authentic to the extent that it is really felt and taken for granted by him/herself and his or her social surroundings” (2001:10). On the essentialism issue, see the relevant sections in Warren (1998) and Fischer (2001). 9. The issue of communications media as a whole requires more formal investigation in terms of how it influences identity and organizing in both urban and rural areas. I suspect that radio and recording media present different stories in terms of bilingualism. From the standpoint of religion in Maya communities, both Catholics and Protestants have access to the airwaves. Moreover, the Protestant traffic in cassette and CD technology with music in Mayan languages as well as Spanish is ubiquitous in the weekly market context. 10. Cojtí and others use this Spanish term frequently in discussing the process of projecting Maya culture into the public sphere. It has not been examined closely enough, although while revising my dissertation for publication I came across a helpful definition of revendicate in the context of Louisiana civil law: “to bring an action to enforce rights in (specific property) esp. for the recognition of ownership and the recovery of possession from one wrongfully in possession.” See the entry at www.merriam-webster.com/legal/revendicate, accessed October 14, 2016. This provides a powerful interpretive framework in light of the attempt to reclaim culture and identity from the Mestizo state while simultaneously pushing for the creation of a multiethnic state. 12. Figures of 30 percent and higher are routinely cited, and occasionally a number as high as 40 percent is given. The 25 percent figure is likely applicable to Chiapas and the states of Yucatán, Campeche, and Quintana Roo as well. In the Guatemalan case (and in Latin America as a whole), 70 percent of Protestants are Pentecostal. To give some time depth, historical Protestants were invited into the country in the early 1880s in the context of efforts by the liberal government to promote modernization and secularization in the face of the Catholic Church. The actual growth rate of evangelicalism appears to have leveled off in the early 1990s, perhaps in part because of the end of the war. 13. The nature of conversion itself is receiving increasing attention in the literature on religion in various disciplines. The notion of conversion as a process makes generalization about the significance of the increasing number of Protestant adherents in various parts of Latin America hazardous at best. See Steigenga and Cleary (2007) for articles that address these issues both theoretically and in various places in Latin America. Humberto Ruz and Garma Navarro (2005) provide a window into the meaning of religious pluralism in contemporary Mesoamerica. 14. See the discussion of “conventions of community” in Watanabe (1992); cf. the sense of communal adaptation discussed in Cook (2001). MacKenzie’s (2010) work examining networks and hierarchy in Maya ethnic activism adds another important dimension for consideration both in Guatemala and in the cross-cultural analysis of ethnic organizing. 15. For more on this kind of inculturated indigenous Protestantism, see also Garrard-Burnett (2004). 16. The references to Tuluán as a place of origin in the ethnohistorical record and the spread of the cult of the Feathered Serpent in the archaeological record highlight the historical influence emanating from the core region of central Mexico. 17. In making these comments, I am drawing largely from some of the conclusions of Bastos (2007:373–78), who analyzes the Maya Movement as a process of “Mayanization” within the frame of a multicultural ideology. REFERENCES CITED
The Impact of the Thermal Comfort Models on the Prediction of Building Energy Consumption Aiman Albatayneh $^{1,*}$, Dariusz Alterman $^2$, Adrian Page $^2$ and Behdad Moghtaderi $^2$ $^1$ School of Natural Resources Engineering and Management, German Jordanian University, P.O. Box 35247, Amman 11180, Jordan $^2$ Priority Research Centre for Frontier Energy Technologies and Utilisation, The University of Newcastle, Callaghan, NSW 2308, Australia; dariusz.alterman@newcastle.edu.au (D.A.); adrian.page@newcastle.edu.au (A.P.); behdad.moghtaderi@newcastle.edu.au (B.M.) * Correspondence: Aiman.Albatayneh@gju.edu.jo; Tel.: +962-06-4294444 (ext. 4218) Received: 13 September 2018; Accepted: 6 October 2018; Published: 10 October 2018 Abstract: Building energy assessment software/programs use various assumptions and types of thermal comfort models to forecast energy consumption. This paper compares the results of using two major thermal comfort models (adaptive thermal comfort and the predicted mean vote (PMV) adjusted by the expectancy factor) to examine their influence on the prediction of the energy consumption for several full-scale housing experimental modules constructed on the campus of the University of Newcastle, Australia. Four test modules integrating a variety of walling types (insulated cavity brick (InsCB), cavity brick (CB), insulated reverse brick veneer (InsRBV), and insulated brick veneer (InsBV)) were used for comparing the time necessary for cooling and heating to maintain internal thermal comfort for both models. This research paper exhibits the benefits of adopting the adaptive thermal model for building structures. It shows the effectiveness of this model in helping to reduce energy consumption, increasing the thermal comfort level for the buildings, and therefore reducing greenhouse emissions. Keywords: thermal comfort; building energy consumption; building simulation; PMV; adaptive comfort; expectancy factor 1. Introduction The building sector is considered to be a large contributor to climate change, since building energy consumption is responsible for releasing approximately 33% of worldwide greenhouse gas (GHG) emissions [1]. Climate change effects need to be reduced by lowering greenhouse gas emissions through engineering solutions and designs to build low-energy, or in other words, energy-efficient buildings. Many studies have shown that energy-efficient or low-consumption energy buildings require the use of passive design solutions to reduce energy consumption [2]. Applying passive design strategies can enhance indoor comfort conditions, while decreasing the energy consumption, by allowing the occupants to lengthen the non-heating and cooling period [3]. The accuracy of thermal comfort prediction is considered to be a beneficial approach, since it is economical and reduces energy consumption [4]. Seven air-conditioned buildings in South Korea were used to examine the effect of occupants’ apparent control in their thermal environments and its effects on cooling energy consumption. The results indicate that increasing occupants’ apparent level of control over their thermal environment could reduce cooling energy consumption by 9% without sacrificing the thermal comfort of the occupants [5]. The accurate thermal comfort design and operation of buildings and Heating, ventilation, and air conditioning (HVAC) systems required taking into account all of the involved factors. Often, building designers overlook or apply them in an incorrect way. Design input values from standards are often considered as universal values rather than suggested values to be used under particular environments. At the operational level, only a small number of variables are considered with unpredictable effects on the calculation of thermal comfort [6]. Thermal comfort is the human experience of satisfaction with the thermal environment, and it is based on inhabitant thermal sensation [7]. Thermal comfort is defined as a “condition of mind”, which is a psychological term. Occupants’ comfort level inside any surroundings may vary and adapt over time due to psychological factors. The individual perception of thermal comfort may be affected by the remembrance of previous experiences. Adaptation takes place when frequent experiences to a certain environment moderates future expectations. This is a significant element in understanding the variance in free-running mode buildings between field results and predicted mean vote (PMV) predictions [8]. Hard labor work in hot humid environments is an actual health and economic danger to millions of working people and their families in hot tropical and sub-tropical climates [9]. The comfort temperature is not a fixed value for everybody, since it is primarily driven by several factors, including air temperature, air speed, and direction, metabolic rate, clothing levels, mean radiant temperature, and humidity [6]. Inhabitant thermal comfort is calculated by measuring the comfort zone of a specific value in terms of occupants [10]. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has developed an industry standard, which is known as the Thermal Environmental Conditions for Human Occupancy / ASHRAE Standard 55-2017. This standard has presented an outline for the categorization of the combinations of interior thermal environment and its personal aspects, which creates thermal environments that are suitable for the mainstream of the inhabitants [10]. There are two main thermal comfort modules used by ASHRAE Standard 55-2010: - The predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD) models, which are also adopted by Comité European de Normalization (CEN) and by International Standardization Organization (ISO) standards. - Adaptive thermal comfort models. The largest energy consumer in the European Union (EU) is the building sector, and toward more energy efficient buildings, a new revised Energy Performance of Buildings Directive (EPBD) (EU) 2018/844 has been published in the European Union Official Journal (L156) and will take effect on 9 July 2018 in order to speed up the pace of new buildings and the cost-effective renovation of current buildings’ renovation on the way to more energy efficient buildings in all of the European Union (EU) countries. This will required the EU countries to transfer the new components of the EPBD into national law by March 2020 [11]. Under the new EPBD, all of the EU countries will have to create more solid “long-term renovation strategies” to decarbonizing the national building by 2050. These strategies need to include a firm financial element, and the new buildings will encourage smart buildings technologies in addition to the health and well-being of building occupants. E-mobility will also be reinforced by introducing minimum requirements for car parks over a certain period [12]. EN15251 specifies “indoor environmental input parameters for the design and assessment of [the] energy performance of buildings addressing indoor air quality, thermal environment, lighting, and acoustics” as the first European standard that contains standards for the four indoor environmental factors: thermal comfort, air quality, lighting, and acoustic. This standard has been broadly used in practice, and several scientific papers have been published dealing with issues related to the adequacy of the standard [13,14]. The European thermal adaptive comfort standard BS EN 15251 is based on ASHRAE 55, and the comfort temperature is calculated in the same way (similar equations but with different coefficients). As there is currently no Australian standard, ASHRAE 55 will be used [15]. REHVA is the Federation of European Heating, Ventilation, and Air Conditioning Associations, and includes more than 100,000 registered engineers. REHVA is devoted to the enhancement of the health, energy efficiency, and comfort in all of the buildings by assisting the knowledge interchange and related policies inside the EU to be implemented at the national level [16]. REHVA has submitted suggestions to revise the Energy Performance of Buildings Directive (EPBD) to promote the use of techniques to enhance the energy efficiency and the indoor environment quality. The EN15251 standard is an outcome of the EPBD, and identifies the standards, principles, and measures for attaining healthier indoor environmental conditions. Other standards are under improvement, such as ISO 17772-1 (ISO, 2017), which targets standardizing retrofits [17–19]. PMV thermal comfort is defined by six variables: air temperature, relative air velocity, mean radiant temperature, mean air humidity, clothing insulation, and metabolic rate. The first four of these variables can be obtained through sensors; however, the assessment of metabolic rate and clothing insulation are dependent on individual users: ISO 9920 (clothing), ISO 8996 (metabolic rate), and ISO 7726 (instruments and methods) [20]. The PMV is established using heat balance principles and data gathered in a controlled climate environment under steady-state conditions. The PMV index predicts the mean response of the general public, as outlined by the ASHRAE thermal sensation scale, as shown in Figure 1. ![Figure 1](attachment:image1.png) **Figure 1.** American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) thermal sensation scale (−1 = slightly cool, −2 = cool, −3 = cold, 0 = neutral, +1 = slightly warm, +2 = warm, +3 = hot). Note: The acceptable thermal comfort range for predicted mean vote (PMV) from the ASHRAE 55-2010 is between −0.85 and +0.85 [10]. There are strengths and limitations for the PMV model. For instance [21], determining the predicted mean vote (PMV/PPD) is a limitation, since information about metabolic rates and clothing insulation are difficult to estimate with accuracy. The PMV for thermal comfort also attempts to find the response of occupants living in the environment in terms of the physiology and physics of heat transfer, which is a complex procedure. It does not consider the psychological factors, which play a significant part in determining the thermal comfort conditions. Many field studies have found that the PMV is challenging to use in the real world, and can lead to inaccuracies in terms of the prediction of comfortable conditions, as it depends on the physiology and subjective perception of respondents [22]. A field study in an air-conditioned office building showed that the adaptive model better fitted occupants’ thermal acceptance than the PMV/PPD model with least energy consumption [23]. Surveys on many buildings have exposed that acceptable indoor environmental conditions are often not achieved. This proposes that the entire building industry needs more precise methods to study and design indoor environments [24–26]. Many studies focus on assisting building and HVAC systems designers and operators to deal with the various and complex standards for improving energy efficiency and indoor environmental quality [6]. As a result of the above complexities, a new method was developed. This method is known as adaptive thermal comfort, and helps building designers calculate the comfortable internal air temperature in free-running buildings. Noting that the adaptive thermal comfort method works only in free-running buildings and not in air-conditioned buildings, while the PMV/PPV works well only in air-conditioned buildings and not in free-running buildings [27]. This adaptive module was developed through several empirical and experimental investigations; it can successfully calculate the internal air temperature by considering several factors such as the interaction of the inhabitants with their surroundings, including when they change their clothes, opening/closing windows, the use of low-energy fans, drinking water, and drawing shades. One of the key outcomes of the adaptive theory is that individuals living in warmer climates can tolerate warmer indoor air temperatures than those who live in colder climates [28]. Comfort area is the area around the neutrality/comfort line and represents the upper and lower comfortable temperature. The 90% and 80% acceptability limits a comfort area with an ideal thermal comfort temperature of 2–3 °C on either side of the comfort line, which is considered to be an acceptable limit, as shown in Figure 2. If fans are available, another 2 °C can be added on both sides to calculate the comfort zone value for very hot, dry, climate conditions. For humid climates, 1 °C can be added on both sides to determine the comfort zone value [29]. The identified range of temperatures match 90% and 80% acceptability limits, and could reach around 30 °C following the adaptive model in the ASHRAE 91 55-2010 Standard [30]. The identified range of temperatures match 90% and 80% acceptability limits, and could reach around 30 °C following the adaptive model in the ASHRAE 55-2017 Standard, as shown in Figure 2. ![Figure 2](image_url) **Figure 2.** The 90% and 80% acceptability limits for indoor operative temperature based on the prevailing mean outside temperature. Expanding the thermal comfort criteria by lowering the acceptability limits from 90% to 70% has a significant impact on space-cooling energy consumption (saving more than 40%) in tropical regions and regions with a hot summer climate [31]. One of the main advantages of the adaptive thermal comfort module is that it eliminates the requirements of calculating air speed and humidity. However, research suggests that in order to analyze the impact of these two factors on the occupant’s thermal comfort, data of the occupants related to windows and doors opened, or fans running, were considered in the analysis [32]. Field experiments were carried out in 26 air-conditioned, and 10 naturally ventilated classrooms using surveys and physical measurements, and indicated that humidity has a very low statistical impact on thermal comfort [33,34]. Naturally ventilated buildings normally consume less than half the energy of air-conditioned buildings because the inhabitants adapt to a considerably broader range of temperatures that fall out of the comfort zone defined by the PMV model [10]. The PMV model also predicts that inhabitants will feel hotter than they actually do, and therefore encourages the consumption of more air conditioning than needed [30]. The adaptive thermal comfort model (by ASHRAE Standard 55-2017 and EN 15251) is used for naturally ventilated buildings, while the PMV/PPD model can be applied in air-conditioned buildings, as it inaccurately directly compares the thermal comfort between the two models. Fanger recommended the expectancy factor, e, to grasp the mean thermal sensation vote of the inhabitants of the actual non-air-conditioned building in a warm climate. The factor “e” varies between 1 and 0.5. It is one for air-conditioned buildings. For non-air-conditioned buildings, the expectancy factor is expected to depend on the length of the warm weather over the year, and whether such buildings can be compared with many others in the region that are air-conditioned; it may be between 0.8–0.9 [35]. Heating and cooling can be reduced when occupants accept wider ranges of internal air temperature, which results in lower energy usage and running costs; therefore, it enhances the economic and environmental performance of the building [36,37]. Inhabitants with greater individual control over their environment have a tendency to accept wider ranges of indoor temperatures. On average, they accepted a 2.6 °C lower operative temperature and showed a lower motivation to modify their current environment (by using air conditioning) compared with those without personal control. It is recommended that inhabitants have a chance to interact with their thermal environment through openable windows and doors, low-energy fans, and minimizing the usage of controllable heating/cooling systems [38]. Using the adaptive thermal comfort model in free-running buildings over the predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) models has proved to be more accurate [6]. The adaptive thermal comfort model saves more building-operated energy in naturally ventilated buildings, compared to air-conditioned buildings, since the occupants adjust to a wider range of internal air temperatures than the external thermal comfort zone, as determined by the PMV model [10]. The PMV model also assumes that occupants will feel hotter than they really are, which gives false data to the air-conditioning systems to lower the operational temperature, ultimately increasing the energy consumption [30]. A case study in the south of Spain of a skyscraper with high-tech energy-efficient features results in a saving of the occupation hours, which reduces the use of air-conditioning equipment by almost 28%, and will significantly reduce the overall skyscraper energy consumption [39]. Cooling and heating can be minimized when inhabitants adapt to wider zones of internal air temperature, leading to less energy consumption and consequently helping to enhance and improve the thermal performance of the building [37]. 2. Methodology This research describes the advantages of using an adaptive thermal comfort model approach to assess the building’s thermal performance over the PMV approach using four full-scale housing test modules located in Newcastle, Australia (cavity brick (CB), insulated cavity brick (InsCB), insulated brick veneer (InsBV), and insulated reverse brick veneer (InsRBV)) subjected to a range of seasonal conditions. The time required for heating or cooling using the adaptive thermal comfort and PMV approach was estimated. 2.1. The Mathematics Behind PMV The predicted mean vote (PMV) model is considered to be the most widely used thermal comfort index today. The PMV equation only applies to humans exposed for a long period of time to steady-state conditions in terms of microclimate and activity. To calculate the PMV model, these equation could be used [40]: \[ PMV = \left[0.303e^{-0.036M + 0.028}\right] \left[(M - W) - 3.96E^{-8}f_{cl}[(t_{cl} + 273)^4 \right. \] \[ - (t_r + 273)^4 - f_{cl}h_c(t_{cl} - t_a) - 3.05[5.73 - 0.007(M - W)] \] \[ -p_a] - 0.42[(M - W) - 58.15] - 0.173M(5.87 - p_a) \] \[ -0.0014M(34 - t_a)\} \] \[ f_{cl} = 1.0 + 0.2I_{cl} \] \[ t_{cl} = 35.7 - 0.0275(M - W) - R_{cl}\left\{[M - W] \right. \] \[ -3.05[5.73 - 0.007(M - W) - p_a] - 0.42[(M - W) - 58.15] \] \[ -0.0173M(5.87 - p_a) - 0.0014M(34 - t_a)\} \] \[ R_{cl} = 0.155I_{cl} \] \hfill (4) \[ h_c = 12.1(V)^{1/2} \] \hfill (5) where - \( t_a \): Air temperature \(^\circ\text{C}\) - \( V \): Relative air velocity inside the room \(\text{m/s}\) - \( f_{cl} \): Clothing factor, accounting for the relative increase in the clothed body surface over that of the unclothed body - \( I_{cl} \): Clothing insulation \(\text{clo}\) - \( R_{cl} \): Clothing thermal insulation \(\text{m}^2\text{K}/\text{W}\) - \( h_c \): Convective heat transfer coefficient \(\text{W/m}^2\) - \( \epsilon \): 10 - \( W \): External work (assumed = 0 \(\text{W/m}^2\)) - \( t_r \): Mean radiant temperature \(^\circ\text{C}\) - \( \text{Met} \): Metabolic index [58.2 \(\text{W/m}^2\)] or [met] - \( t_{cl} \): Surface temperature of clothing \(^\circ\text{C}\) - \( p_a \): Partial pressure of water [KPa]. The variables were collected from data recorded inside the site, while the pressure and humidity levels (air humidity equal to 80% could be over the range of water partial pressure required by the module) were obtained from the Bureau of Meteorology Australia [41] as the experimental modules in free-running moods and no inhabitants or activities inside it, as shown in Table 1. Table 1. Variables that define predicted mean vote (PMV) thermal comfort [10]. <table> <thead> <tr> <th>Parameter</th> <th>Unit</th> <th>Range of PMV/PPD (ISO Standard 7730)</th> <th>Note</th> </tr> </thead> <tbody> <tr> <td>Metabolic rate</td> <td>Met (W/m²)</td> <td>0.8–4.0</td> <td>1 for seated and 1.7 for cooking</td> </tr> <tr> <td>Clothing insulation</td> <td>Clo (m²K/W)</td> <td>0.0–2.0</td> <td>0.5 for the hot days and 1.3 for the cold</td> </tr> <tr> <td>Mean radiant temperature</td> <td>°C</td> <td>10.0–30.0</td> <td>Close to the outside air temperature</td> </tr> <tr> <td>Air temperature</td> <td>°C</td> <td>10.0–30.0</td> <td>Recorded inside each module</td> </tr> <tr> <td>Air velocity</td> <td>m/s</td> <td>0.0–1.0</td> <td>Main driver for air is natural circulation</td> </tr> <tr> <td>Air humidity</td> <td>%</td> <td>55–80</td> <td>Recorded at 9 a.m. and 3 p.m.</td> </tr> </tbody> </table> PPD is defined as the proportion of inhabitants that are uncomfortable within their thermal environments. The suggested suitable PPD thermal comfort zone is less than 10% of occupants, who are dissatisfied with their situation [10]. PPD is a function of PMV (the average response of satisfaction among a large group of people). The empirical relationship between the PPD and the thermal environment is a function of the PMV [16] as following [42]: \[ PPD = 100 - 95e^{(-0.03353 \text{ PMV}^4 - 0.2179 \text{ PMV}^2)} \] \hfill (6) 2.2. Adaptive Thermal Comfort For this research, the adaptive thermal comfort temperature for free-running buildings has been adopted (mechanically cooled or heated buildings have been excluded because of two reasons: their complex nature and lesser stability). The relationship between the comfort temperature \( T_c \) and the outdoor temperature \( T_o \) for a temperate climate in Australia is as described below [29]: \[ T_c = 17.8 + 0.31T_o \] \hfill (7) where \( T_o \): The average of the outdoor air temperature for the previous 30 days (°C). \( T_c \): Comfortable temperature (°C). To find the adaptive thermal comfort of 80% of the acceptability limit inside the building, the following equation is used [29]: \[ 80\% \text{ acceptability higher limits} = T_c + 3.5 \degree C \quad (8) \] \[ 80\% \text{ acceptability lower limits} = T_c - 3.5 \degree C \quad (9) \] Equation (8) represents 80% of the acceptability limits, where at least 80% of the inhabitants are comfortable with these temperatures. The main requirement of using this module is that the occupants are assumed to be inactive and that the mechanical cooling or heating system has not been installed. The metabolic rates should range between 1–1.3 Met (physical activities in winter will warm the body, but in summer, it will make them feel hotter). The occupants are encouraged to adjust their clothing according to the weather conditions, within a range of 0.5–1.0 Clo [10]. 2.3. Full-Scale Test Modules For the past 13 years, ongoing research has been underway in the Priority Research Centre for Energy at the University of Newcastle, Australia, on the thermal performance of housing in Australia. A part of this research has included the building of four full-scale housing modules, incorporating a range of typical walling systems and monitoring their thermal performance under different weather conditions. All of the modules were constructed at the University of Newcastle, Callaghan Campus (Latitude: 32.89° S, Longitude: 151.71° E). The houses have been designed to represent the types of housing that are commonly constructed in Australia. Apart from the walling systems, all of the modules had a similar design, with a square floor plan of 6 m × 6 m and spaced 7 m apart to reduce wind obstruction and avoid shading (see Figure 3). Figure 3. (a) Full-scale test modules; (b) north and (c) south plans for all of the modules [17–23]. All of the modules have the same design [43–49]. - Door; heavily insulated door in the southern wall, to eliminate any heat losses and allow easy access to the module. - Window; in the northern wall of each module is a 6.38-mm laminated clear glass window, in a light-colored aluminum frame. - Roof; 10 mm plasterboard ceiling with R3.5 glass wool batt insulation (thermal resistance of 3.5 m²·K/W) between rafters. Concrete and clay tiled roof with sarking insulation. - Slab; concrete covers the whole building floor, with 100-mm thickness. The only difference between the modules is the walling system, which is identified in the following: 1. Cavity Brick Module (CB) Walling for the CB module consisted of two 110-mm brickwork skins with 10-mm render covered internal walls and a 50-mm cavity between the walls, as shown in Figure 4. 2. Insulated Cavity Brick Module (InsCB) For the InsCB module, two 110-mm brickwork skins and the internal walls were covered by 10 mm of internal render with a 50-mm cavity insulated by R1 polystyrene insulation, as shown in Figure 5. 3. Insulated Brick Veneer Module (InsBV) For the InsBV walls, the external walls were constructed using 110-mm brickwork skin, while the internal walls consisted of an internal timber frame covered with low-glare reflective foil and R1.5 glass wool batts, and covered by 10-mm plasterboard, as shown in Figure 6. 4. Insulated Reverse Brick Veneer Module (InsRBV) For the external walls, 2–3 mm acrylic render on 7-mm fibrocement sheets were fixed on a timber stud frame, and insulated by R1.5 glass wool batts insulation. For the internal walls, a 110-mm brick skin was covered by a 10-mm internal render, as shown in Figure 7 [43–49]. ![Cavity brick module walling system](image1) **Figure 4.** Cavity brick module walling system. ![Insulated cavity brick module walling system](image2) **Figure 5.** Insulated cavity brick module walling system. ![Insulated reverse brick veneer module walling system](image3) **Figure 6.** Insulated brick veneer module walling system. ![Insulated reverse brick veneer module walling system](image4) **Figure 7.** Insulated reverse brick veneer module walling system. First, 105 sensors were fitted in each module to record the internal and external conditions. The sensors were installed in each module with a minimum of 40 sensors as required by ASHRAE 55 to measure the thermal comfort performance of a small room. The sensors were distributed on the walls and in the middle of the module away from the occupied boundary, radiation, and diffusers. The data were recorded using Datataker DT600 data loggers every 5 min for 24 h/day over the testing period. All of the modules were air tight and left to “free float”, with the internal air temperature being influenced by the external weather conditions alone (no mechanical heating or cooling for all of the modules). The internal air temperature was logged at a height of 1200 mm inside the building. No mechanical ventilation was provided during the study period [43–49]. The accuracy of the PMV values is adequate only when the difference between the mean radiant temperature and the air temperature is less than 5 °C [20,50]. The difference between the mean radiant temperature and the air temperature within indoor environments is negligible during most periods [51]. In this research, the mean radiant temperature were calculated by finding the average temperature of all of the sensors located inside the room and the operative temperature calculated by finding the average air temperature for the sensors located in the middle of the building at different heights: 600 mm, 1200 mm, and 1800 mm. The monthly average internal air temperature inside each module was recorded in order to find the PMV for each month and determine which months required heating and cooling to maintain thermal comfort. The equations to calculate the PMV have been implemented in a software tool that is available freely on: http://smap.cbe.berkeley.edu/comforttool. For the adaptive thermal comfort model, the total number of hours during which the internal air temperatures fell outside the occupants’ comfort range was calculated for each module using the 80% acceptability limits [52]. 3. Results and Discussion This research indicates the importance of using an appropriate thermal comfort model to predict the energy consumption inside any envelope; also, the assessment of the thermal performance using adaptive thermal comfort model simplifies the analysis and saves more building operation energy. On the other hand, using the predicted mean approach encourages energy consumption by using energy to sustain inhabitants’ thermal comfort and giving inaccurate energy needs predictions. The predicted mean vote (PMV) was found for one year for all of the modules. The results of the cavity brick (CB) module are shown in the psychometric chart (see Figure 8), which presents the relationship between the air temperature and the humidity in graphical form. Data from the housing test modules are used, with the exception of humidity and pressure, which was obtained from the weather station on campus (as the building in free-running mode, and there are no occupants or any activities inside the modules). There are many apps and web applications to calculate the PMV index compliant with ISO 7730 Standard. Unfortunately, limited apps take into account all six variables, so these tools have to be used with special care [53]. The equations to calculate the PMV have been implemented in a software tool that is available freely on: http://smap.cbe.berkeley.edu/comforttool [52]. As an example, the monthly average internal air temperature inside the cavity brick module was recorded to find the PMV for each month and determine which months required heating and cooling to maintain thermal comfort. In Figure 9, the entire months of May, June, July, August, September, and October, were outside the thermal comfort zone, indicating that half of the year required thermal heating for the CB module to sustain thermal comfort. Figure 8. Psychometric chart for average monthly temperature outside the thermal comfort zone for the cavity brick (CB) module. Note: the blue region indicates the comfort zone. The PMV values were calculated using the same software tool for each hour, over one year, to find the number of hours for each module, which lay within the thermal comfort zone (as shown for Figure 9 for the CB module as an example). For each of the modules, the numbers of hours for each module where the internal temperature outside the thermal comfort zone were: 4993 h, 4292 h, 4205 h, and 4030 h per year, for the CB, InsCB, InsRBV, and InsBV modules, respectively. Figure 9. Psychometric chart presents the hourly temperature for the CB module within the thermal comfort zone. The adaptive thermal comfort ranges of the 80% acceptability limits are shown in Figure 10 (CB modules). The external and internal temperature fluctuations inside/outside the buildings over one year are shown, where the green line represents the adaptive thermal comfort temperatures, and the red lines are the higher and lower 80% acceptability limits. The 80% acceptability limits will broaden the thermal comfort zone, for example in January between 22.7 °C to 29.7 °C in summer and 19.6 °C to 26.6 °C in winter. These broader zones will potentially maintain significant amount of imposed, operational energy when incorporated into building assessment tools. However, some of the occupants may be slightly uncomfortable with the new temperature ranges; however, this can easily be overcome with extra actions to restore their thermal comfort (e.g., summer ventilation, shades, fans, physical activities, and suitable clothes for winter). For all of the modules, the temperatures fall below the thermal comfort ranges in May, August, September, October, and most of June and July, while in November and December, the temperatures remain within the comfortable range. Figure 10. Internal, external air temperatures and the adaptive thermal comfort ranges of the 80% acceptability limits for the CB module. It can be seen that mechanical heating or cooling would be required mainly for the winter months. The total number of hours during which the internal air temperatures fell outside the occupants’ comfort range were calculated for each module using the 80% acceptability limits for the adaptive thermal comfort model (these were 2623 h, 2499 h, 2199 h, and 1921 h per year for the cavity brick, insulated brick veneer, insulated reverse brick veneer, and insulated cavity brick modules, respectively). The results for the entire year are shown in Figure 11. Utilizing the wider ranges of the adaptive thermal comfort model have reduced the predicted cooling and cooling loads compared with the PMV by 21%, 18%, 21%, and 25% for cavity brick, insulated brick veneer, insulated reverse brick veneer, and insulated cavity brick modules respectively, as shown in Figure 12. when designing any building, since it is economical and reduces energy consumption to a level of around 20%. The accuracy of the thermal comfort prediction is considered to be a significant amount of energy. The internal thermal comfort model; this is used to estimate heating and cooling energy requirements to ensure that an acceptable level of thermal comfort for the occupants is achieved with the least amount of energy. The accuracy of the thermal comfort prediction is considered to be a significant amount of energy. Adaptive thermal comfort techniques. Various optimizing power management policies were studied and optimized [54]. One way of reducing electrical power consumption is through the use of modern energy-efficiency techniques in order to reduce the cost of utilizing a kilowatt-hour unit. The other method focuses on energy conservation and utilizing energy only when there is a demand for it; since a lot of energy is “lost” when there is a lack of energy conservation, this can be achieved by using the adaptive techniques. Various optimizing power management policies were studied and optimized [54]. An important part of any building energy assessment program is the use of an appropriate internal thermal comfort model; this is used to estimate heating and cooling energy requirements to ensure that an acceptable level of thermal comfort for the occupants is achieved with the least amount of energy. The accuracy of the thermal comfort prediction is considered to be a significant when designing any building, since it is economical and reduces energy consumption to a level of around 20%. The main issue of applying an adaptive approach is the limitations of the adaptive thermal comfort equation for each country and for each climate zone inside each country, which required more research. Figure 11. Total numbers of hours where mechanical heating or cooling were required using adaptive thermal comfort. Figure 12. Total numbers of hours where mechanical heating or cooling was required for PMV and the adaptive thermal comfort. Figure 12 indicates that there is a substantial potential saving of energy with the use of the adaptive thermal comfort approach. This can be applied to real-life situations to promote low-energy solutions to sustain thermal comfort by changing occupant behaviors with strategies such as the use of appropriate seasonal clothing, low-energy fans, sun shades, opening windows/doors, or even drinking more water instead of using HVAC systems. to determine the comfortable temperature range for each climate zone. Also, the adaptive approach required occupants to perform small actions to maintain their thermal comfort, and failing to do so will result in thermally uncomfortable feeling. These results required further research to establish and facilitate the claim of the adaptive thermal comfort as a replacement thermal assessment model. 4. Conclusions The accuracy of the simulation of the building’s thermal performance is known to have a significant impact on energy costs, energy consumption, and greenhouse gas emissions. Consequently, to overcome these issues, an appropriate thermal comfort model is needed to determine and measure the accurate and precise value of thermal performance. The designing of energy-efficient buildings involves the use of thermal comfort models (such as the predicted mean vote or adaptive thermal comfort approaches). These models are used to determine the energy consumption (heating and cooling loads) of the building to reach an appropriate level of thermal comfort for the occupants. The use of an appropriate thermal comfort model will provide building designers with more reliable evidence on thermal building performance, when calculating the heating/cooling loads and selecting the most suitable HVAC system (heating, ventilation, and air conditioning). The performance analysis of the four Newcastle (Australia) housing test modules was conducted by the use of the “free-floating” mode. The adaptive thermal comfort model was used to determine the cooling and heating time period, which were shown to be almost half of the values obtained by using the PMV model (21%, 18%, 21%, and 25% for the cavity brick, insulated brick veneer, insulated reverse brick veneer, and insulated cavity brick modules, respectively), since the adaptive model offers broader thermal comfort zones, ranging from 22.7 °C to 29.7 °C in summer and 19.6 °C to 26.6 °C in winter. These broader zones have the tendency to improve the energy efficiency of the building. Although slight discomfort may be experienced by the buildings’ occupants, due to new wider ranges of temperatures that could be outside the thermal comfort for some occupants, this can be overcome by using low-energy solutions (such as the choice of suitable clothing, the use of shades, ventilation, and/or fans, more physical activities in winter, and drinking more water), instead of reverting to the use of mechanical heating or cooling devices. The final results showed that the use of the appropriate thermal comfort model to predict building’s energy consumption decreases the time that is essential for cooling or heating by almost 20% when compared with the PMV model through lengthening the non-heating and cooling period. Funding: This research received no external funding. Conflicts of Interest: The authors declare no conflicts of interest. References 27. d’Ambrosio Alfano, F.R.; Olesen, B.W.; Palella, B.I.; Riccio, G. Povl Ole Fanger’s impact ten years later. *Energy Build.* 2017, 152, 243–249. [CrossRef] 40. Albatayneh, A.; Alterman, D.; Page, A.W.; Moghtaderi, B. Warming issues associated with the long term simulation of housing using cfd analysis. *J. Green Build.* 2016, 11, 57–74. [CrossRef] © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Imprecision Dr. Nicholas Rescher Distinguished University Professor of Philosophy Department of Philosophy, University of Pittsburgh Pittsburgh PA 15260, U.S.A. Tel: +1-412-624-5950 E-mail: rescher@pitt.edu Homepage: http://www.pitt.edu/~rescher/ Abstract: This paper surveys the various modes of imprecision and seeks to clarify the concept of imprecision, to account for the pervasiveness of the phenomena, and to explain why we have to come to terms with it throughout our cognitive affairs. The structure of these deliberations will be as follows: Having set the stage for considering imprecision (in section 1), it will briefly elaborate upon each of them (in section 2). Next comes a discussion of two of the main ramifications of imprecision, namely vagueness (section 3) and oversimplification (section 4). There follows (in section 5) a consideration of why imprecision is inevitable in our cognitive dealings, and why this feature of investigation actually admits of an evolutionary explanation. The paper concludes (in section 6) with a retrospective glance at the overall situation from a philosophical point of view. Overall, the discussion is of an analytical cast, seeking to clarify the conceptual nature and operational bearing of imprecision within the cognitive scheme of things. Keywords: Cognitive limits; Detail; Exactness; Imprecision; Knowledge; Oversimplification; Precision; Error; Cost-effectiveness JEL Classifications: A100, A120, B400, B500 1. Introduction Precision and detail are widely accepted as key desiderata for inquiry. But often these virtues are not achievable to the desired extent, and in consequence, the prospect, and indeed the reality of imprecision extends its reach across the entire range of our thought and discourse. Alike in theory and practice, and in the physical and human sciences, the factors of precision/imprecision plays a crucial role. And this factor of precision/imprecision takes many forms and has many versions.¹ Among the modes of diminished detail, five are particularly prominent: Quantitative imprecision. When we characterize someone as a short man or a tall woman we do not thereby give any indication of just how old or just how tall. Descriptive imprecision. When we say that something is blue in color or oval in shape we do provide useful descriptive information but of a rather vague and indefinite sort. We are undeniably inexact about the matter. ¹ Precision and detail is inherently different from accuracy and correctness. An incorrect assessment can be very precise—and conversely. An evaluation that is both precise and accurate is said to be valid. Classificatory imprecision. When we call something a chair or a knife we remain very indefinite on the matter. One cannot say whether (say) it is a bread knife or a steak knife or a fruit knife that is at issue. Locational imprecision. When we say that one thing is near another or one place distant from another, we do not indicate anything about the extent to which this is so. Relational imprecision. In saying that lions are carnivores we need not claim that this is so always and necessarily or only obtains ordinary and normally. Scholars have used the term precision to indicate the exclusion of irrelevant possibilities since medieval times. And some among Renaissance neo-scholastics held that a precise knowledge of reality was beyond the reach of finite intelligences: nostrum cognitionum nulla sane praecisast, an idea which was a central theme in the De docta ignorantia of Nicholas of Cusa. And yet among our contemporaries the issue has fallen on hard days, generally ignored throughout the contemporary theory of scientific knowledge. Notwithstanding the evident importance of the topic surprisingly little attention has been directed to it. The search for terms like “precision,” “exactness,” “detail,” and the cognates in standard works of reference such as The Stanford Encyclopedia of Philosophy of the Encyclopedia of the Social Sciences meets with resounding silence. It is a “fact of life” that information on virtually any theme or topic can be conveyed in more or less precision and detail. And this clearly has extensive ramifications and indications for the nature of human cognition. In consequence, the issue of precision/imprecision deserves to constitute one of the central topics of the rational economy of knowledge. It represents a theme that ties together a varied set of key issues: approximation in measurement, puzzles of evaluation, paradoxes in logic, vagueness in language, and much else. 2. Major Modes of Imprecision For very large $N$ the value of $1/N$ becomes approximately zero, and with increasing $N$ we can bring it as close to zero as ever we please—no holds barred. In the limit it comes to zero. But be $N$ however large in the end this quality will always stand off at a distance from zero with its bearing that of an approximation. Such a quantitative version of imprecision is perhaps its most familiar form. Most of the quantities that concern us in everyday life are imprecise. People may well know their weight to within a few pounds, but it is questionable whether the idea of “someone’s weight to within a milligram” even makes sense. And the same is true of such quantities as: - The distance between two cities to within a foot - The age of a person to within a millisecond - The height of a giraffe to within a millimeter - The value of a piece of property to within a dollar --- 3 Ibid. p, 1215. All such quantities are by nature approximate and inexact: Not only is precision not attainable here, it is questionable whether it is even meaningful. Yet such qualities, although figuring importantly in everyday-life matters, are nevertheless such that with them the demand of absolute precision leads not to greater clarity and illumination, but rather into an ultimately imperceptible fog of unknowing. Theoretical quantities—the value of pi, say, or of the square root of two—can be exfoliated ongoingly to endless decimal places. But the quantitative features of most of the spatio-temporal reals that lie within the range of our experience will by this very circumstance have to remain imperfectly precise. Were matters otherwise, we would never be in the positon to make claims about the overall basis of what we can practicably determine. And this it is so obvious to us that this is so that terms like “roughly,” “approximately,” “more or less,” etc. are unnecessary qualifications because their presence is taken for granted as an evident fact. And it would be counter-productive to insist that proper quantities must necessarily be exact, because then most of what we deal with under this nomenclature would simply have to be recast under the rubric of quasi-quantities. Whenever the equations governing the phenomena that concern us are such that very small variation in the input parameters can make for substantial variation in the resulting output, then of course precision is of the essence. The classic illustration of descriptive imprecision is color. For us, snow is white whereas the artic Inuits purportedly have dozens of terms of the appearance of snow. For laymen someone is simply an insurance agent, while for economists he falls into a wide variety of specialists dealing in life, fire, heath, maritime, travel, etc. insurance. The layman’s wine descriptions run to white and red; current or vintage; while wine aficionado’s elaborate this into many dozen categories. A description is vague insofar as its application in given cases is unclear. Are airships ships? Are whales fish? Are tomatoes fruit? Are witch-doctors doctors? Uncertainty in application is the hallmark of impression. Descriptive imprecision arises from the fact that the language we are invariably given to oversimplifying the variability of the world’s arrangements—that language provides merely limited measures to deal with matters that are of limitless variability. Our everyday terminology is invariably generic and inexact in conveying a wide spectrum of more precise possibilities. And this, of course creates problems. Thus with wines, what of rosé—where does white leave off and red begin. With insurance just how many subcategories can qualify? Does the company that guarantees your car’s engine function as an insurer or not? Many legal issues revolve around such subtleties. Not only does virtually every type have multiple subtypes, but it is often unclear and indeterminate whether a possible-constructive subtype is actually so. Where do shrubs leave off and trees begin? Which early humanoids actually qualify as humans? Where does blue start and green begin? The inherent imprecision of the key turns of these questions make them ultimately unanswerable with exactitude. Just as is the case with descriptions classifications too are almost always imprecise. For most classifications have sub-classifications so that the question “Of what kind?” or “Of that sort?” will repeatedly arise, with further detail and precision thereby required. With dogs we can ask “Of what species”, with buildings we can ask “Of what sort?” And as such questions are answered, further ones will arise. And even if no absolutely lowest species can be found so that the question “Of what kind?” become problematic, nevertheless further descriptive detail can always be demanded to identify an item and distinguish it from its infimum species congers. For even items that are classificatorily identical will be descriptively distinguishable from others.\(^5\) An imprecise boundary exists whenever it is not possible to specify with complete exactitude just where the transition from IN and OUT is located. In evolution the boundary between pre-human humanoids and homo sapiens is of this nature. In the color spectrum the boundary between blue and green is also imprecise. And this itself is not a matter of surgically neat separation. For when the boundary between IN and QUESTIONABLE (and that between the latter and OUT) can be fixed exactly. With these boundaries themselves we have an instant replay of the original division problem. And this, in effect, is bound to continue ad infinitum. There is no precision to imprecision, no exactness to inexactness. Still we unhesitatingly say that when you cross the threshold of a room you are out “up to a certain point” and in thereafter. But of course no-one can specify just where that point is: precise exactitude cannot be achieved. And this is all to the good. For in such situations exactitude just does not matter. You are on the witness stand and the prosecutor asks you “When did the accused enter the room?” His witness responds: “At about 3:15” or “Somewhere between 3:10 and 3:20.” And this response is sufficiently informative. In managing life’s affairs, precision often does not matter—and when it does so it is all too often unachievable. In many contexts the law imposes for the sake of administrative practicability an arbitrary precision for which nature provides no sensible warrant. When is a young person old enough to act responsibly in matters of contract-making, marriage, drinking alcohol, voting, etc.? Some are there by the age of 15, others have yet to arrive at 30. But the law picks a convenient number, and imposes an arbitrary precision on parameters that Nature fears to touch. Two approaches are available here: (1) “With this inexact boundaries there indeed is an exact transition point \(Q\) but we cannot possibly find it out.” (2) “With these inexact boundaries there just is no exact transition point \(Q\) and we just have to make do with something that is inherently imprecise and should be seen as viable surrogate for something that is strictly speaking nonexistent.” From the standpoint of (2), (1) would constitute a fallacy of improper reification—what Immanuel Kant called an “illicit hypothetization.” What we have here are two decidedly different approaches. The latter mode of transition point rejection is ontological: those so-called points are inexistent and illusionary—a sort of cognitive mirage invoked to make sense of a larger picture. (Akin to the *focus imaginarius* of a representational painting.) The former approach, by contrast, sees the transition point as real but inherently unspecifiable. For some facts are by nature unknowable. Nobody can identify the smallest integer that will never be specifically and divisibly referred to. No one can specify an ancient Etruscan who has been altogether forgotten. There is a crucial difference between: (1) The description \(D\) is known to have no application whatsoever: \(K\sim (\exists x)Dx\). (For example, “the largest prime.”) --- \(^5\) What is at issue here is the classic “Principles of the Identity of Indiscernibles.” (2) The description \( D \) has no known application: there is nothing of which we know that it answers to \( D \sim (\exists x) \text{KD}x \). (For example, “the largest integer that anyone on earth will ever specifically and individually discuss.”) These statements make very different sorts of claims, and there will be many cases where (2) is true, but (1) is not. An example is provided by the description “a fact that is known to no-one,” for while there clearly are facts that no finite being knows, yet we cannot possibly identify any of them. Thus consider such items as: I1 an idea that has never occurred to anybody I2 an occurrence that no one ever mentions I3 a person who has passed into total oblivion I4 a never-formulated questions I5 an idea on one any longer mentions I6 a never-stated contention (truth, theory, etc.) I7 a never-mentioned topic (idea, object, etc.) I8 a truth (a fact) no one has ever realized (learned, stated) I9 someone whom everyone has forgotten I10 a never-identified culprit I11 an issue on one has thought about since the 16th century Yet while there undoubtedly are such items, they of course cannot possibly be specifically instantiated. Such predicates are “vagrant” in the sense of having no known address of fixed abode. Though they indeed have applications, these cannot be specifically instanced—they cannot be pinned down and located in a particular spot. Accordingly, \[ F \text{ is a vagrant predicated if } (\exists u)Fu \text{ is true while nevertheless } Fu_0 \text{ is false for every specifically identified } u_0. \] And so the idea of items that exists but are inherently unspecifiable as per these (2) above can certainly not be rejected out of hand.\(^6\) It is simply not the case that whenever something demonstrably exists that this item can be specifically and individually identified. Not only can particular statements about specific items be imprecise but generalizations can also be so. For vague terms and indefinite categories open the door to qualified generalizations. Consider the situation of Display 1. In the sharp-boundary situation of Case I we clearly have it that “All \( F \) are \( G \)’s” But in the indefinite-boundary situation of Case II some of the \( F \)s may or may not be \( G \)s. All we can say here is that “In general [usually, almost always standardly, normally] the \( F \)s are \( G \)s.” Rather than a strictly universal generalization we here have one that is merely standardistic or normalistic. And such generalizations are not strictly universal but only normatively general; they admit the prospect of exceptions. They tell us how things are usually, normally, ordinarly, as a rule, standardly, other things equal, *ceteris paribus*. \(^6\) On this issue of vagrant predicates see the author’s *Epistemetrics* (Cambridge: Cambridge University Press, 2006), pp. 87-92. When true, such generalizations are not strictly universal laws but only quasi-laws. Their explanatory power is real but limited. They admit exceptions, which can—and generally will be—accounted for on the basis of the underlying processes at work. Display 1. Modes of Imprecision <table> <thead> <tr> <th>Case I</th> <th>Case II</th> </tr> </thead> <tbody> <tr> <td><img src="image" alt="Diagram" /></td> <td><img src="image" alt="Diagram" /></td> </tr> </tbody> </table> A science whose explanatory proceedings resorts to such as-a-side quasi-laws is not an exact science but an inexact one. Its generalizations will feature the sort of *ceteris paribus* character typical of the social sciences. (Consider, for example, such generalizations as “Price increases lead to diminished sales” or “People react angrily to insults.”7) Such generalizations lack Immanuel Kant’s strict universality and necessity, but admit the more relaxed standard of the ordinary and usual course of things.8 3. Paradoxes of Vagueness Imprecision has important ramifications for logic and the theory of language. Perhaps the most striking of these are manifested in the traditional “Paradoxes of Imprecision,” whose paradigm instances stems from classical antiquity. Foremost among them is the “Paradox of the Heap”—the *Sorites Paradox* (from the Greek *sôros* = heap)—is posed in the following account: A single grain of sand is certainly not a heap. Nor is the addition of a single grain of sand enough to transform a non-heap into a heap: when we have a collection of grains of sand that is not a heap, then adding but one single grain will not create a heap. And so by adding successive grains, moving from 1 to 2 to 3 and so on, we will never arrive at a heap. And yet we know full well that a --- 8 The explanatory principles of Aristotelian science contemplated generalizations that were not true invariably, but only held in general and “for the most part”. On the issues of this section see the author’s *Philosophical Standardism* (Pittsburgh, PA: University of Pittsburgh Press, 1994). collection of 1,000,000 grains of sand is a heap, even if not an enormous one.\textsuperscript{9} A near cousin to this paradox is the ancient Ship of Theseus Paradox, based on the tale of the ship which was ongoingly repaired, with defective planks ongoingly replaced by others until there was not a sliver of the original left. It is claimed that at the end of the process we are not longer dealing with the same ship, seeing that no bit of material remains to betoken this sameness. And yet it seems that we cannot but grant that when a single plank is replaced in a large vessel that ship remains the same. So just how and just when did that ship leave off being the same one with which we began? A closely analogous paradox is the story of Sir John Cutler’s hard-used Stockings. Over time they were repaired bit by bit until not a thread of the original was left and finally not a bit of the original remained. At the start there was the original pair but at the end something altogether different. But there seems to be no immediate point when a change-over can be pin-pointed. Moreover, consider the situation of what might be called the \textit{Color-Continuum Paradox}. We lay out a long row of color patches: say 100 of them. Any two adjacent ones are colorwise indistinguishable to the unaided eye. But gradually and imperceptibly we shift over to quite a different color by the time we get to the end of the series. We thus arrive at the aporetic cluster represented by the following four theses: (1) Patches whose color is visually indistinguishable (to a normal observer in normal circumstances) have the same color. (2) Patches [1] and [2] are colorwise visually indistinguishable, as are patches [2] and [3], and so on up to patches [99] and [100]. (3) Hence—all these patches have the same color (by (1)). (4) Nevertheless, patches [1] and [100] are clearly seen to have patently different colors. Taken together, these thesis are logically inconsistent. But (2) and (4) are straightforward facts, and (3) follows from (2) by (1). Accordingly, it is the more suppositional (1) that must be abandoned seeing that we have to distinguish between an item’s \textit{phenomenal} color at issue in the antecedent of (1) and its \textit{measurable} color at issue in the consequent. Color identity is something more complex than what can be settled by visual means alone. However, we would again presumably not wish to abandon (1) altogether—and there is no need to do so. But would have to demote it from the realm of the rigidly universal to that of the merely general. This would provide for its continued availability in other deliberations despite its contextual untenability in the present case. And herein lies a larger lesson. All such paradoxes pivot on invoking a universal premises of the format: {G} $(\forall x)(\text{whenever } Fx, \text{ then } Gx)$ \textsuperscript{9} On this paradox and its ramifications see Chapter 2 of R. M. Sainsbury, \textit{Paradoxes} (2nd. ed., Cambridge: Cambridge University Press, 1995), pp. 23-51. Originally the paradox also had a somewhat different form, as follows: Clearly 1 is a small number. And if \textit{n} is a small number so is \textit{n} + 1. But by iteration this leads straightway to having to say that an obviously large number (say a zillion billion) is a small number. (See Prantl, \textit{Geschichte der Logik}, Vol. I, [Leipzig, S. Hirzel, 1855], p. 54.) In particular those cited paradoxes pivot on claims on the order of - \((\forall n)\) (whenever \(n\) grains do not constitute a heap, then \(n + 1\) grains will not do so.) - \((\forall n)\) (whenever a group of \(n\) planks make up a certain ship, then the group that replaces just one of them and leaves the remaining \(n - 1\) planks in place does so as well [i.e., makes up the self-same ship].) - \((\forall n)\) (whenever a complex of \(n\) threads make up a certain stocking, then the complex with one single replacement (the other \(n - 1\) threads remaining the same does so as well [i.e., makes up the selfsame stocking].) But just here lies the key that unlocks the paradox. For the existence of vague terms compels recognition that there are two very different sorts of generalizations, viz. those that are strictly universal and subject to the traditional \(\forall\)-quantifier of absolute universality, and those that are only standardistically general and subject to the limited \(\forall^*\)-quantifiers of qualified generality.\(^{10}\) All of those aforementioned paradoxes of vagueness become dissolved once it is acknowledged that they commit a Fallacy of Overgeneralization in taking that what is normally and standardly the case to be so universally and without exception. 4. Oversimplification Imprecision is correlative with oversimplification. For imprecision overlooks detail and the lack of attention to detail is exactly what constitutes oversimplification. Oversimplification always leads to errors of omission. It occurs whenever someone ignores features of an item that bear upon a correct understanding of its nature. However, this is not the end of the matter. For such errors of omission all too readily carry errors of commission in their wake. An oversimplified script may make it difficult to distinguish between \(q\) and \(g\) and thereby invite the confusion of quest and guest. The oversimple counting system of one-two-three-many opens wide the door to misjudgment about quantities. However, some oversimplification is inevitable for limited intelligences seeking to come to grips cognitively with an endlessly complex world. For the totality of facts about a thing—about any real thing whatever—is in principle inexhaustible and the complexity of real things is in consequence descriptively unfathomable. The botanist, herbiculturist, landscape gardener, farmer, painter, and real estate appraiser will operate from different cognitive “points of view” in describing one selfsame vegetable garden. And there is in principle no theoretical limit to the lines of consideration available to provide descriptive perspectives upon a thing. The cardinal feature of reality is its inherent complexity. There are always bound to be more descriptive facts about actual things than we are able to capture with our linguistic machinery: the real encompasses more than we can manage to say about it: oversimplification regarding the world’s arrangements is inevitable for us. It is a sound methodological principle of rational economy to “Try the simplest solutions first” and then to make this result do as long as it can. For rationality enjoins us to operate on the basis of \(^{10}\) Traditionally, logicians dealt only with strictly universal and existential quantifications as per \(all\) and \(some\) and \(none\). The idea of merely pluralistic qualification (“many,” “most,” “almost all,” “exactly four,” etc.) was introduced by the author in 1962. (For details one might ask any search engine under the rubric “Rescher quantifier.”) Occam’s Razor—considerations are never to be introduced where they are not required: complexity is never to be provoked beyond necessity. Our theories must be minimalistic: they must fit the existing data tightly. And this means that as our data are amplified through new observations and experiments the previously prevailing theories will almost invariably become destabilized because those old theories oversimplified matters. New conditions call for new measures, new data for more complex theories. It lies in the rational economy of sensible inquiry that the history of science is an ongoing litany of over-simple old theories giving way to more sophisticated new ones that correct their oversimplification of the old. Imprecision has been the ongoing Leitmotiv of scientific progress. 5. Why Tolerate Imprecision? Being imprecise about a date may put a decision into the wrong administration and thereby give a wholly erroneous view of its policies. Being imprecise about the location may put one into the wrong jurisdiction and give incorrect indications regarding matters of legality. Imprecision leads to error. The great benefit of imprecision is that it enable us to convey information much more readily. Consider the question of the height of a person. We can specify this to the nearest foot by mere inspection. To measure it to the nearest inch takes a bit of doing (and requires a yardstick or some such). To specify it to the nearest millimeter becomes something between difficult and impossible. And this situation is typical: A seesaw relationship obtains between infiniteness and detail. The greater the detail that is demanded the fewer questions we can answer conscientiously. Abandoning imprecision altogether would result in cognitive impoverishment. Why then tolerate imprecision? Why not always and everywhere insist on exactitude—as lawyers are wont to do in drawing up contracts and agreements? In the end, it makes good sense to accept imprecision whenever: - We have no option because greater detail is unavailable. We are simply doing the best we can, making the best effort to accommodate order to a regrettable reality. - We have no need for more because greater detail does not matter. We can solve our problems and answer our questions satisfactorily at a level of diminished detail. - We cannot afford to do better because greater detail would be too costly and while it might indeed be available its realization would demand an unaffordable expenditure. The unwelcome reality of it is that precision compromises tenability. The greater the precision of a claim, the more demanding the evidentiation for it becomes. That the weight of yon elephant is great is obvious, that it is roughly 2½ tons is determinable, its weight in ounces would take a great deal of doing. Establishing that yon leaf is green is obvious, that it is of lighter green than grass requires some effort, that it is exactly green #34 in a spectrum of 100 shades of green likely requires a lot of work. --- 11 On issues regarding oversimplification see Chapter 6 of the author’s Cognitive Complications (Lanham etc.: Lexington Books, 2015). Precision is simply unachievable in certain matters. Illustrations of this phenomena have already been considered and it is simply impossible in the very nature of things to achieve absolute exactness with respect to matters of - The height of a person - The weight of an elephant - The age of an inventor - The location of a firefly Specifications of this sort rest on factors that simply cannot be purported with precision. Precision makes transformation transmittal cumbersome. The attempt to specify not precision such factors as - The age of an invention - The magnitude of a consideration - The size of a crowd is but to require endless qualifications and elaborations. Precision is not needed in many informative situations. If someone threw a rock through the window, it is of no concern whether this was a chunk of sandstone or granite. If someone made a payment of $100 it matters little whether the bills were 10s or 20s. When someone is notified of having been chosen for jury duty it matters little whether this was done by post, or telegram, or special messenger. In all such matters details is pretty much irrelevant. Here, as in many or even most communicative situations, it is the just of the issue that alone matters. Precision is not needed for most practical purposes. When I am considering whether or not to take my umbrella it matters not whether the forecast is for 1 inch of rain or 1½ inches. When I am considering going to the dentist, it matters little whether my toothache is severe or excruciating. In practical contexts of action and decision, precision need to be of concern beyond the needs of the immediate situation at hand. In various sorts of situations, precision and accuracy (i.e., precise correspondence with reality) are simply not of the essence. Thus consider the Display 2 situation of two tic-tac-toe grids, set up to depict a certain hypothetical Realty and Appearance, respectively. (Here ? indicates indecision as between 0 and 1.) The Appearance situation is certainly nowise a precise reflection or representation of Reality. (Agreement is provided for in only two out of the nine cases.) But let it be that what is in questions is the principle: (P) Every 0 entry is adjacent to a 1 entry, and conversely. Then the Appearance picture, gravely wrong though it is, provides the correct answer. Even so simple an example conveys an important lesson: Whether or to what extent detail matters critically depends upon just exactly what the issue under consideration happens to be. Precision is not a free good: Achieving exactness and enhancing precision is not a cost-free enterprise; it is costly. To achieve precision one must go to great lengths. If cake recipes called for great precision, bakeries would have to close. In increasing exactness cost and complication increase exponentially. For insofar as precision/exactness/acrimony can be measures it is clear that a principle of decreasing returns is in play with each successive 10% increase costing, some several times (the expenditure of recourses and effort as its predecessors. Imprecision is a natural response to the demands of economy and conservation of effort. If our communicative discourse had to meet high statistics of precision the exchange of information would become difficult if not impracticable. 6. Conclusion Imprecision plays a prominent role in our thinking because it is a requisite for the evolutionary development of the intelligent beings who guide their actions by thought with regard to their situation. Were exactness required we would not be here to tell the tale. If a type of creature is to endure and thrive in an evolutionary environment, nature has to cut it a great deal of slack. It must not critically matter for its survival just exactly what type of nourishment it requires or just exactly what type of environing conditions possibilize its existence. And if this sort of creature happens to be an intelligent being whose interactions with the world are shaped by thought and belief this ontological slack is mirrored in a cognitive imprecision. If eggs were only edible if cooked at a precise age we would not be eating eggs. If the nutrient value of fruit depended on the exact time of day when they were harvested their place in our diet would be greatly reduced. The dispensability of precision in matters of life-sustaining action is essential to our viability as the sort of intelligent beings we humans are. On first thought we incline to regard impressions as a flaw in the compilation and transmission of information. But close attention to the issues indicates that this is itself an oversimplification. For this pervasive presence is not only inevitable in practice but desirable in theory, given the conditions under which we must function in the management of information. Functionless perfection is as impracticable in matters of cognition as in thermodynamics. 12 This contention—itself a model of imprecision—shows the utility of this feature in conveying “the general idea” at issue. In closing, it seems fitting to survey the principal conclusions of the preceding discussion. They stand as follows: - Imprecision can take many forms. The most familiar is quantitative imprecision or approximation, but also descriptive, classificatory, locational, and relational imprecision, among others. - Whether and how greatly precision matters depends on the particular context of application. (Whether 1 or 4 inches of rain will fall will not matter for deciding whether or not to take an umbrella.) - Classificatory precision can be of the essence in legal matters: Whether an airship counts as a ship is crucial for issues of admiralty law. The law often imposes arbitrary precision (e.g. in relation to quantifying an adult able to enter into contracts). - The tolerance of imprecision is crucial to loose quasi-generalizations such as “Price increases diminish sales” (they often don’t), or “Fatigue diminishes performance” (it often does not). - Oversimplification and its correlative imprecision is often rational—especially in cases where accuracy and precision is hard to secure and makes no substantial difference. All in all, it emerges on closer scrutiny that imprecision, although a seeming deficiency, is a factor that can in many situations pay for itself in terms of collateral benefits. Depending on the context, the toleration of imprecision can be a highly cost-effective practice. Aristotle tells us in the Nicomachean Ethics that “it is the mark of an educated man to look for precision in each class of thing just insofar as the nature of the subject admits. (1094b-24-26). He hold that we shall not pursue precision beyond the limits of necessity. But the present analysis takes a somewhat different, more pragmatic line: it argues for the futility of requiring precision beyond the limits of utility. For in virtually all contexts, theoretical and practical alike, there is only so much precision we can use, and considerations of rational economy mandate that there is no point to carrying matters further. References
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Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.uk Abstract The evolution of residual stress and microstructure has been investigated in electron-beam welded Ti-6Al-4V alloy rings in order to develop an understanding of how the distribution of through-thickness residual stress correlates with microstructural evolution. A multiple technique approach to residual stress measurement was employed using a combination of different measurement techniques including X-ray diffraction (XRD), hole drilling method based on electronic speckle pattern interferometry (ESPI), and the contour method. It was found that there is a strong correlation between the change in residual stress and alpha phase morphology across the weld. The fusion zone exhibited highly tensile residual stress which was typified by an entirely acicular $\alpha'$ microstructure formed by a displacive transformation within prior $\beta$ grains on cooling. The tensile residual stress in the centre of the weld reduced towards the heat affected zone, transitioning to a compressive residual stress upon increasing distance from the weld centre. The transition from tensile to compressive residual stress correlates with a significant decrease in the volume fraction of $\alpha'$ and an increase in the bimodal morphology of equiaxed primary alpha in a diffusional transformed beta matrix leading to elongated alpha in the base material. Keywords X-Ray Diffraction Weld Residual Stress Contour Method Titanium Alloys Phase Transformation 1. Introduction Titanium alloys are often selected as structural components for use in a number of applications due to their favourable strength-to-weight ratio, corrosion resistance and temperature resistance [1]. The aerospace industry accounts for majority significant amount of global titanium consumption (i.e. over 50%) and is commonly used in the airframe, landing gear and gas turbine engines [2]. The sixty-year-old α + β type alloy Ti-6Al-4V is the most widely used titanium alloy, acting as an integral constituent of many aerospace components. Joining technologies are essential to the manufacture of gas turbine engine parts; therefore ensuring structural integrity is pivotal to the endurance of critical components in service. Electron-beam welding is one of the most popular joining techniques in the manufacture of gas turbine engines. Electron-beam welding produces three distinct zones in the welded material including the fusion zone (FZ) which undergoes melting and re-solidification, the heat affected zone (HAZ) which is subjected to a solid state thermal cycle, and the base metal (BM) which is largely unaffected by the welding process [3]. The application of heat treatment can potentially lead to tailored mechanical properties in Ti-6Al-4V, however, thermal gradients during welding typically result in undesirable changes to the original microstructure, causing deviations from bulk mechanical properties [4]. This presents a number of challenges, most notably in the formation of undesirable residual stress and microstructure [5]. Most manufacturing processes such as forging, welding, machining and quenching are associated with the generation of residual stress [6]. Residual stresses can be thought of as internal stresses, required to maintain equilibrium, which remain in a part when it is no longer subjected to any external applied loads [7]. These residual stresses can be induced by heterogeneous plastic deformation, differential thermal fluctuations or due to phase transformation and precipitation [5]. Thus, residual stresses are often generated due to welding operations, as at least one of these mechanisms occurs during welding [8-10]. The inclusion of undesirable residual stress (i.e. tensile) can be detrimental to the life of a component [11, 12]. A recent review by Fairfax and Steinzig [13], which analysed 147 residual stress related incidents within the ASM Failure Analysis Database™, found that over 37% of incidents were directly attributable to joining-related failures. Additionally, residual stresses may lead to distortion during the manufacturing process of machining due to material removal which leads to the redistribution of residual stresses [14]. Determining the nature and magnitude of such stresses is therefore of critical importance to the manufacture and performance of welded Ti-6Al-4V components. A limited number of investigations have been carried out which characterise the microstructure and residual stress distribution of welded Ti-6Al-4V, with little work attempting to interrelate the two [15-19]. It has been reported that the microstructure of electron-beam welded Ti-6Al-4V in the FZ, HAZ and BM is primarily composed of the following phases: martensite (α’), α’ + α + β, and α + β, respectively, with the volume fraction of α’ decreasing linearly across the HAZ from the FZ to the BM [17, 18]. Typically, fusion welded joints exhibit a peak tensile residual stress within the FZ, which tends to decrease throughout the HAZ, leading to balancing compressive zones in either side of the weld [20]. Further from the weld, the residual stress becomes a function of both the original residual stress existing in the BM prior to welding and those induced by the weld itself [3]. Mehdi et al. [16] identified and assessed both the microstructure and residual stress of Ti-6Al-4V tungsten inert gas (TIG) fusion welds. XRD was used to determine that the surface residual stress distribution is related to the prior β grain size in the FZ and volume fraction of different phases across the weld region. However, the use of XRD for residual stress analysis produces a collection of single point surface data, which does not allow for a through-thickness understanding of the residual stress magnitudes and distributions in a component. On the other hand, the contour method can be applied to produce a 2-Dimensional (2D) map of out-of-plane residual stress [21]. The method has also been demonstrated on Ti-6Al-4V extruded profiles [22]. Nevertheless, it has been noted that limitations in Electrical Discharge Machining (EDM) cutting quality can lead to high uncertainties within 0.5 mm of the contour sample edge [23]. Special care can be taken to mitigate these uncertainties, requiring verification by means of additional measurements using techniques such as hole-drilling and XRD [23]. Xie et al. employed the contour method alongside XRD in order to successfully verify the near-surface accuracy of the contour method when applied to 50 mm electron-beam welded Ti-6Al-4V plates [15]. Thus, established methods with low depth penetration such as XRD and hole-drilling techniques can be used to compliment and verify the near-surface results of the contour method. This can lead to a comprehensive understanding of through thickness residual stresses in a part which can then be interrelated to microstructural observations. Despite the above, little work has been conducted regarding the application of multiple residual stress measurement techniques upon electron-beam welded Ti-6Al-4V to develop an understanding of how the distribution of through-thickness residual stress correlates with microstructural evolution. This paper aims to present a clear understanding of the magnitude and distribution of welding induced residual stress and microstructure evolution in electron-beam welded Ti-6Al-4V. A focus on residual stress measurement was maintained throughout this work, with the resulting findings interrelated to the microstructural evolution and microhardness profile for two weld cases. 2. Material and Methods 2.1 Material and Processing A total of two circumferentially electron-beam welded rings made from Ti-6Al-4V, labelled Ring 1 (shown in Fig. 1) and Ring 2, were selected for these investigations. The nominal chemical composition of the material used in these rings is outlined in Table 1. The two rings had dissimilar part geometries and were subjected to differing welding conditions, which allowed for the identification of common trends in residual stress and microstructural evolution, and therefore aided the transferability of the findings as well as helping to identify differences due to weld parameters. Weld parameters and ring dimensions are given in Table 2 and Fig. 2. The microstructure of the rings is largely elongated primary alpha in a transformed beta matrix. This suggests that the hot ring rolling process was conducted at subtransus temperatures. Fig. 1. Photograph of Ti-6Al-4V welded sample Ring 1. Table 1. Nominal chemical composition for Ti-6Al-4V alloy used in study (wt%). <table> <thead> <tr> <th>V</th> <th>Fe</th> <th>Al</th> <th>O</th> <th>C</th> <th>N</th> <th>Ti</th> </tr> </thead> <tbody> <tr> <td>4</td> <td>0.25</td> <td>6</td> <td>0.13</td> <td>0.08</td> <td>0.03</td> <td>Bal.</td> </tr> </tbody> </table> Table 2. Weld parameters and ring dimensions (Note: The weld of Ring 1 was performed in one single pass, while Ring 2 was subjected to additional cosmetic pass, resulting in two complete passes). <table> <thead> <tr> <th>Ring ID</th> <th>Weld conditions</th> <th>Geometry</th> </tr> </thead> <tbody> <tr> <td></td> <td>Weld speed (mm/s)</td> <td>Axial clamping pressure (bar)</td> </tr> <tr> <td>1</td> <td>30</td> <td>210</td> </tr> <tr> <td>2</td> <td>20</td> <td>‘low pressure’</td> </tr> </tbody> </table> 2.2 Microstructure Characterisation In an attempt to understand the interrelationship between microstructural evolution and the resulting residual stress distribution of electron-beam welded Ti-6Al-4V, samples were prepared for light microscopy. Specimens were sectioned radially from both rings to reveal the microstructure in the FZ, HAZ and BM close to the weld regions. Subsequent metallographic preparation was performed in line with standard techniques including the use of Kroll’s Reagent (2% HF, 6% HNO₃, 92% H₂O) to reveal the alpha and beta phase morphology, following grinding and polishing to mirror finished condition using a Nikon Eclipse lv1 150, and analysed using Buehler Omnimet. 2.3 Microhardness Measurement In order to provide additional evidence of microstructural evolution in the welded rings, following the microstructural characterisation, a Struers Durascan G5 microhardness testing machine was used to measure a hardness map on the sample cross section; including the BM and different zones of the weld. These measurements were acquired to ASTM E-384-16 standard using a diamond shaped Vickers indenter by applying a 0.5 N load with a 15 s dwell time. Indentations were made on a rectangular grid covering the weld cross section, with 1 mm spacing in both radial direction and axial direction between indentations, and a 1 mm distance between the closest indentations and edge of the sample. Indentations were analysed with a 40× objective lens, zoom 1, to produce a micro-hardness map. 2.4 Residual Stress Measurement Residual stress analysis was carried out on each welded ring using a combination of (1) XRD, (2) hole-drilling based on ESPI, and (3) the contour method. For each welded ring, one radial cross-section was selected for the contour method, and two measurement lines were identified for XRD and ESPI stress measurements. These are shown schematically in Fig. 2. This allowed for the investigation of the axisymmetric of hoop stresses throughout the rings and, if verified, would provide additional comparison with the contour method results. A number of measurement points were selected in the FZ, HAZ and BM along these surface profiles to provide an understanding of the surface and near-surface residual stress distribution in both axial and hoop directions, and allow for later comparison with the results of the contour method. ![Fig. 2. Schematic illustration of the welded rings with position of the welds and the dimensions of the BM material, (a) Ring 1, (b) Ring 2. The location of contour method residual stress measurements are highlighted in green, and the surface profiles for the XRD and ESPI based hole-drilling measurements are highlighted in red.](image) 2.4.1 X-ray Diffraction The XRD technique is commonly employed to determine surface residual stresses [24]. XRD was carried out using an automated PROTO LXRD X-Ray diffractometer system and the sin²ψ method [25]. A copper anode target was selected to obtain diffraction peaks from the \{211\} crystallographic planes of alpha phase. The stresses were then calculated from the strains of the \{211\} Bragg reflection at 140° Bragg angle, assuming Young’s modulus of 118 GPa and Poisson’s ratio of 0.342. At least nine measurements were performed on the identified surface profiles for each ring (see Fig. 2) in both hoop and axial directions, at points with higher density in the weld regions and with increased point spacing towards the BM material, encompassing the weld and BM on either sides of the weld. For each point in both directions, 11 measurements with a 3 s exposure time for each measurement were performed. These were sufficient to obtain an adequate number of counts to construct strong peaks used for stress analyses. A round collimator with 1 mm radius and ten $\psi$-offset angles in the range of maximum $\pm$ 30° were employed. Separate gain profiles were gathered for the BM, HAZ and FZ to account for variations in Bremsstrahlung background radiation due to the differing fractions of constituent phases present throughout the material. 2.4.2 Hole-drilling with ESPI Hole-drilling based on ESPI was used to provide near surface measurements of hoop and axial residual stress components at a limited range of successive depths from the surface. This was conducted using a Stresstech Prism® system; which consisted of a high speed drill, laser source, and a CCD camera. The laser source produces a monochromatic wavelength of 532 nm. Tungsten carbide drill bits were used when carrying out the procedure. Two drill bit diameter sizes of 1.8 mm for measurements on the BM, and 1 mm for those on the FZ were used. Holes were drilled at depth increments up to 60% of the drill diameter corresponding to 1 mm depth for the BM, and 0.6 mm for the FZ. For each ring, two sets of measurements were performed in the BM ($z = +20$ mm), with a further two in the FZ ($z = 0$ mm) on the surface profiles, at precisely the same spots as those measured by XRD, shown schematically in Fig. 2. The through depth residual stress profiles were then calculated from the optically measured surface displacement data assuming a Young’s modulus of 118 GPa and a Poisson’s ratio of 0.342. 2.4.3 Contour Method The contour method was carried out on both welded rings in order to provide a full 2D map of hoop residual stress distribution in the samples. This included the task of releasing bending moments, as described by Prime [26], which act as an additional source of hoop residual stress. The measurement for each ring was carried out in four main steps: (i) sample cut, (ii) measurement of cut surface profiles, (iii) data processing, and (iv) calculation of residual stress using finite element simulations; that are discussed in the following. A total of two cuts were made by electrical discharge machine (EDM) on each samples using a 250 µm brass wire in ‘skim’ cut mode in the radial direction on the radial-axial plane starting from the outer diameter. For each sample, the first cut was conducted to release the bending moments and quantify the opening caused by the partial relaxation of hoop stress induced by bending moment [26]. For this purpose, a pair of scribed lines separated by 10 mm was made along the axial direction of the sample, and then the cut was conducted between the lines. Following the first cut and unclamping the sample, the relative displacement of the scribed lines was measured. The measured displacements were used as boundary conditions for the calculation of bending moment stresses. The second cut was then conducted at an increment of 120° clockwise from the first cut that was used as the basis for residual stress measurement by contour method. The sample was clamped on both sides of the cut planes appropriately during the cutting process. Upon completion of the EDM cuts, for each sample the outline and surface topography were measured on either side of the skim cut in a temperature controlled environment using a Mitutoyo Crysta Apex C coordinate measuring machine (CMM) with a 2 mm ruby attached to a Renishaw PH10T touch probe. The CMM equipment was programmed to acquire data with a spatial resolution of 400 µm for points in both in-plane directions. The measured data obtained for both surfaces of each skim cut were cleaned to minimise outliers and system noise. The data from both sides of the cut were then aligned in the same coordinate system by considering the whole perimeter of each half of the cut as an alignment guide to match the whole outlines. Following the alignment process, the datasets for both sides were linearly interpolated onto a common grid, after which the two sets were averaged. The pitch of the common grid was equivalent to that of the original data in order to produce the average surface point by point. A set of knot spacing ranging from 0.4 mm to 15.4 mm was chosen and a bivariate cubic spline for each knot spacing was fit to the averaged data. A knot spacing of about 4 mm was selected for both rings as an appropriate value. A 3D finite element (FE) model assuming isotropic elasticity with a Young’s modulus of 118 GPa and a Poisson’s ratio of 0.342 was used to evaluate the residual stress from the surface contour data. For this purpose, the perimeter of the cross-section for each sample was modelled using the aligned outline measured by the CMM. The 2D cross-section was then revolved circumferentially for 180° and 120° to produce 3D models, respectively for the calculations of bending moment induced stress and residual stress. Mesh seeds were attributed to each node on the outline and also along the revolved perimeter of the model that are used as guidelines for the generation of mesh. The establishment of the seeds were biased by allocating a finer pitch near the cross-section of the model representing the cut surface, and coarser pitch towards the other end of the model that is of a less importance for stress analysis. The parts were modelled in Abaqus CAE and meshed with an element spacing of 0.8 mm on the cut surface, and 0.8–10 mm with single bias away from the surface. The selected element type was C3D20R; 20 node brick quadratic elements, as used by Prime et al. [27]. For the residual stress model, the stresses were calculated by forcing the cut surface into the opposite shape of the averaged contour data [22, 23]. For the calculation of the stresses released after the first cut (i.e. bending moment) a symmetry plane was used to constrain one surface of the model while applying bending moment on the other surface by using concentrated forces. The stresses induced by the bending moment were considered as those achieved after the deformation of the symmetry model for the same magnitude of opening displacement, with opposite sign, measured experimentally following the first cut for each sample. Both the bending moment induced stresses and the residual stresses calculated on the cut surface were integrated to achieve the final magnitude and distribution of residual stress. 3. Results 3.1 Weld Microstructure The light micrographs obtained for Ring 1 show three distinct microstructures for different regions of the weld, each characterised by varying microstructural features [Fig. 3]. These regions include the FZ, HAZ and BM, the microstructures of which are dictated by the thermal history during welding. It is evident from [Fig. 3a] that the FZ is almost fully comprised of acicular $\alpha'$ in prior columnar $\beta$ grains which is a characteristic of diffusion-less shear transformation of $\beta$ upon fast cooling from the welding temperature. There is some evidence of epitaxial growth of these columnar FZ grains originating from the HAZ. The HAZ can be characterised as a transition region with regards to microstructure and can therefore be subdivided into the near and far HAZ with respect to the FZ; where the microstructure is dependent on the local temperature in relation to the material’s martensitic start temperature ($M_s$). It is apparent from the micrograph presented in [Fig. 3b] that the near HAZ (left) primarily consists of acicular $\alpha'$, similar to that of the FZ yet with a distinct morphology. The far HAZ (right), however, has a microstructure more representative of the BM. From [Fig. 3b] there is a visible decrease in the volume fraction of $\alpha'$ from near to far HAZ as the local temperature during welding decreases below the $M_s$. As volume fraction of $\alpha'$ decreases, it is replaced by an increasing presence of fine scale globular $\alpha$ and $\beta$ lamellae in prior $\beta$ grains, and equiaxed $\alpha$ at prior grain boundary $\alpha$ ($\alpha_{gb}$). Therefore between the FZ and the HAZ there is a transition from a shear dominated to diffusion dominated phase transformation. The fine scale primary alpha becomes coarsens and becomes elongated towards the BM, and is shown in [Fig. 3c]. Similarly to Ring 1, light micrographs of Ring 2 showed evident signs of microstructurally unique FZ, HAZ and BM regions, as shown in [Fig. 4]. However, there was an additional ‘secondary HAZ’ attributed to the cosmetic pass (see [Fig. 4d]), identified as a fourth region close to the outer diameter of the ring; replacing the original FZ in this region, see Fig. 5 for details. There is an evident macrotexture in the secondary HAZ with a directionality towards the centre of the weld. Further increases in magnification revealed faint equiaxed $\alpha$ grains and transformed $\beta$, identified as ‘ghost $\alpha$', shown in [Fig. 4d]. ![Fig. 3. Optical micrographs of the weld zones of Ring 1. (a) FZ, (b) HAZ, and (c) BM.](image-url) 3.2 Weld Microhardness The microhardness results presented in Fig. 6 provide further evidence of microstructural evolution and strength variations across the weld, extending from the BM on one side to the BM on the other side, covering all the regions. An area of 21 mm × 12 mm was considered for each ring; starting at a depth of 1 mm from the outer surface, and axially centred on the weld. In Ring 1, the maximum microhardness reading was 416 HV, with a minimum of 273 HV; whereas values ranged from 292 to 416 HV for Ring 2. The average hardness was found to increase from ~ 330 HV in the BM to ~ 370 HV in the FZ of both Ring 1 and Ring 2. The obtained microhardness data for the HAZ shows a transition between the FZ and BM for both rings, correlating with the optical micrographs presented in Fig. 3 and Fig. 4. The FZ of both rings were typified by a region of increased hardness, as shown in Fig. 6a and b. This tended to decrease throughout the HAZ towards the BM; which generally displayed a lower hardness. The overall trend in microhardness is clear, however, there were isolated patches of increased hardness in the BM, which is noticeable in Fig. 6b. The line plots of averaged y-axis microhardness across the weld in the z-direction (Fig. 6c and d) further highlight the increased hardness of the FZ compared to the BM in both rings. ![Image](image.png) **Fig. 6.** 2-D microhardness maps across the electron-beam welded regions in (a) Ring 1, and (b) Ring 2. Accompanying line plot of mean microhardness across the weld in (c) Ring 1, and (d) Ring 2. ### 3.3 Weld Residual Stress The hoop and axial surface residual stress components obtained by XRD for both samples are presented in [Fig. 7a](image.png) and [Fig. 7b](image.png), respectively. These results display a tensile hoop stress region in the FZ and HAZ, with peak residual stresses of $+ 513 \pm 58$ MPa for Ring 1 and $+ 792 \pm 65$ MPa for Ring 2, in the centre of the weld. Compressive residual stresses were measured in the BM of both samples with peak values of $- 727 \pm 10$ MPa for Ring 1 and $- 601 \pm 18$ MPa for Ring 2. In Ring 1, all measured axial surface stresses were compressive; ranging from $- 81 \pm 50$ MPa to $- 534 \pm 51$ MPa. On the other hand, Ring 2 generally exhibited tensile axial residual stresses in the HAZ and FZ with a maximum of $+ 385 \pm 34$ MPa, reducing to a more stable compressive residual stress as distance from weld centre increased. There is a good agreement between the data collected for both surface profiles (i.e. XRD 1 and XRD 2); particularly in the BM, providing evidence of an axisymmetric residual stress distribution across the sample surface. It should be noted that there were some discrepancies observed between the XRD residual stress results in the FZ, however this may be due to the residual stress gradient across the weld coupled with the ± 1 mm lateral spatial resolution of the technique [24]. Depth profiles of residual stress distribution quantified by hole-drilling based on ESPI for the FZ (z = 0 mm) and BM (z = + 20 mm) of both samples are provided in Fig. 8 displaying the data obtained for both surface profiles (i.e. ESPI 1 and ESPI 2) in the hoop and axial directions. The corresponding surface residual stresses for these zones, as quantified by XRD, are also presented in Fig. 8 for reference. In the FZ, tensile hoop stresses were measured at all depths, with maximum values of + 860 ± 50 MPa at a depth of 0.35 mm for Ring 1 (see Fig. 8a) and + 898 ± 50 MPa at a depth of 0.36 mm for Ring 2 (see Fig. 8c). Axial residual stresses in the FZ of Ring 1 were found to vary between tensile and compressive in nature with very small magnitudes as depth increased (see Fig. 8a). However, axial stresses were found to be mostly tensile for the FZ of Ring 2 (see Fig. 8c), with a maximum value of + 263 ± 50 MPa at a depth of 0.36 mm. Both rings showed a similar trend in BM residual stresses; with highly compressive hoop and axial stresses leading to a relatively stable value (see Fig. 8b and d). This ranged from between roughly 0 to −50 MPa and −50 MPa to −100 MPa for axial and hoop stresses, respectively, at depths of 0.1 mm to 1.2 mm. The ESPI based hole-drilling results provide further confirmation of axisymmetric residual stress distribution; with good accordance between surface profiles upon increasing depth. Fig. 7. XRD residual stress data across the weld for Ring 1 and Ring 2. (a) Hoop stress, and (b) Axial stress. The opening distances measured between the scribed lines induced by bending moments were 2 mm and 2.2 mm for Ring 1 and Ring 2, respectively. These correspond to stresses which vary almost linearly from approximately 25 MPa on the outer surface to about 35 MPa on the inner surface for both rings. Fig. 9 shows the contour plots of the averaged surface height obtained by the CMM for both samples, following the EDM skim cut for contour residual stress measurement. The range of peak to valley of the contours was roughly 70 µm for Ring 1 and Ring 2. The contour plots show that the surface height in both samples is low in the weld region implying that tensile residual stresses are relieved. The out-of-plane hoop residual stresses for Ring 1 and Ring 2, as evaluated by combining the bending moment stresses and the results of contour method, are provided in Fig. 10. Fig. 8. Surface and near surface residual stress profiles measured by XRD and hole-drilling based on ESPI as functions of depth at different regions of Ring 1 and Ring 2 welds. (a) FZ of Ring 1 at z = 0 mm, (b) BM of Ring 1 at z = + 20 mm, (c) FZ of Ring 2 at z = 0 mm, and (d) BM of Ring 2 at z = + 20 mm. From the out-of-plane hoop stress map for Ring 1 provided in Fig. 10a, it can be seen that tensile residual stresses (i.e. light blue to red) were concentrated within the FZ and HAZ. The region of highest tensile residual stress was identified in the FZ between depths of 3–9 mm on the y-axis, with the peak stress reaching +495 MPa. The remainder of the sample surrounding the FZ and HAZ was in a state of compression, as expected. Highly compressive pockets of residual stress (i.e. dark blue) were identified at approximately −7.5 mm and +7.5 mm the weld centre in the z-axis, with a peak compressive stress of −300 MPa exhibited. Additionally, regions of increased compressive stress were found near the outer diameter of the BM on either side of the weld. The contour method residual stress results for Ring 2 (see Fig. 10b) showed two regions of high tensile stress in the FZ; one on the outer surface, and the other between the centre and inner surface of the part. The maximum tensile stress across the cut plane exceeded that of Ring 1, reaching a peak residual stress of +755 MPa near the outer surface of the FZ. Considering the 2D hoop residual stress maps for both rings, it is clear that residual stress in the weld region decreases almost linearly in the \(-z\) and \(+z\) direction, with Ring 1 and 2 displaying differing linear and hyperbolic shapes respectively. Such a relationship agrees with the microhardness data in Fig. 6 where Ring 1 exhibits a wider region of high hardness over the weld zone compared to Ring 2. This is shown in Fig. 11 by plotting the residual stress profiles across the whole weld cross-section along the \(z\)-axis. Additionally, from Fig. 10b it was noted that Ring 2 exhibited a protrusion in tensile residual stress along the inner diameter of the ring, up to roughly 27 mm away from the weld in the \(-z\) direction. A corresponding balancing zone of highly compressive residual stress was observed towards the ring inner surface, away from the tensile protrusion, with a maximum value of \(-625\) MPa. Plots of surface, near-surface, and through-depth residual stress were produced by combining the results of all investigated measurement techniques for each welded ring. Particular focus was given to the FZ in the weld centre (i.e. \(x = z = 0\) mm) and the BM at a distance of \(\approx +20\) mm from the weld centre (\(x = 0\) and \(z = +20\) mm) on the outer surface. The residual stress profiles measured by contour method, extracted from the 2D contour plot data presented in Fig. 10 and the results obtained by XRD and hole-drilling based on ESPI are presented as functions of depth within 2.5 mm of the outer surface. These results are shown in Fig. 12. Contour method data was excluded for depths between the surface and 0.5 mm due to the reduced accuracy of the technique within this range when compared to that of the other employed techniques [23]. Fig. 10. Out-of-plane 2D hoop residual stress maps of samples as determined by the contour method and bending moment for (a) Ring 1, and (b) Ring 2. Fig. 11. Residual stress profiles across the weld cross-section (i.e. along the z-axis in Fig. 10) taken from the residual stress maps measured by contour method presented in Fig. 10 for (a) Ring 1 at y = 8.4 mm, and (b) Ring 2 at y = 8.2 mm. **Fig. 12.** Combined results of XRD, hole-drilling based on ESPI and contour method hoop residual stress as functions of depth \( y \) within 2.5 mm of the outer surface for (a) FZ of Ring 1 at \( z = 0 \) mm, (b) BM of Ring 1 at \( z = +20 \) mm, (c) FZ of Ring 2 at \( z = 0 \) mm, and (d) BM of Ring 2 at \( z = +20 \) mm. The plot of surface and near-surface depth stress profile of the FZ of Ring 1 (see Fig. 12a) displays tensile data for all applied techniques. Upon consideration of the depth plot in the BM of Ring 1 (see Fig. 12b), the residual stress distribution is shown to be compressive for all points. Similarly, all data points for the FZ (see Fig. 12c) and BM (see Fig. 12d) of Ring 2 are tensile and compressive, respectively. There is good agreement between contour results and ESPI based hole-drilling data in the FZ and BM of both rings. This is especially evident in the BM of Ring 1 and Ring 2 from depths of 0.5 mm to approximately 1.15 mm, with all contour and ESPI data within the bounds of measurement error throughout this range [23]. ### 4. Discussion The residual stress profiles obtained using XRD, hole-drilling with ESPI and the contour method showed good agreement, verifying the results of the contour method and allowing comparison with microstructural observations. Since the cut for contour method was conducted after the relaxation of bending moments, the errors associated with plasticity in the tip of the cuts were minimised [23]. The contour method provided an approach to easily measure and evaluate through thickness hoop residual stress. However, the technique has some limitations with regards to sensitivity. High residual stress gradients were present in the parts; identified across the weld and near the BM sample surface. These stress distributions may not be accurately depicted due to the selected element size being too large and/or the selected spline knot spacing over-smoothed the surface topography data, and in turn affecting the residual stress results [28]. Knot spacing and element size selection also leads to extracted contour data points representing a number of small segments with averaged residual stress in place of point measurements (e.g. XRD or ESPI based hole-drilling) which can better capture peaks in residual stress [23]. For the purposes of understanding bulk residual stress distributions across the weld, the wavelength covered by the contour method is adequate. However, it is also often important to have an understanding of surface and near-surface residual stresses with high spatial sensitivity due to the role of such residual stresses during fatigue crack initiation [7]. Therefore, the utilisation of XRD and ESPI based hole-drilling proved complimentary to the contour method by offering a means of contour verification as well as determination of high fidelity surface and near-surface residual stress with relatively short wavelength which cannot be captured accurately by contour method. The general 2D through thickness distribution of hoop residual stresses in both rings, as presented by the contour method, depicted a tensile region in the FZ. This decreased in magnitude across the HAZ, developing into highly compressive pockets in the BM, and then slightly decreasing in magnitude to a relatively steady compressive value as distance from weld increased. This distribution is as would be expected for a typical electron-beam weld [3, 15]. The peak tensile hoop residual stresses of both rings were obtained by ESPI based hole-drilling in the FZ. These were recorded at similar depths; + 860 ± 50 MPa at a depth of 0.35 mm for Ring 1 and + 898 ± 50 MPa at a depth of 0.36 mm for Ring 2. This is similar to the maximum residual stress of + 914 MPa measured by Xie et al. using the contour method on electron-beam welded Ti-6Al-4V plates of 50 mm thickness [15]. In order to compare the residual stress to the material yield strength, the effect of varying microstructures across the weld must be considered. Wang and Wu linked the microstructure to the yield strength of electron-beam welded Ti-6Al-4V joints, with the BM, HAZ and FZ corresponding to yield strengths of 932 MPa, 892 MPa and 857 MPa respectively [18]. There are differences between the aforementioned study and the work conducted in terms of material geometry, weld conditions and BM microstructure. However, based on these properties the peak tensile stress recorded in the FZ would be in the range of the material yield strength. Such highly tensile residual stress is undesirable and post weld heat treatment may be applied to reduce such residual stresses in industry [3, 15]. Although the obtained data provides evidence to support the expected general trends in residual stress distribution, there are some dissimilarities in magnitudes and profiles between the two investigated rings. These dissimilarities may be due to the differences in welding conditions, sample geometry and additional cosmetic pass. For example, the tensile region in Ring 2 is smaller than that in Ring 1, which can be attributed to the reduced welding power used. This leads to a lower heat input, reducing the size of the FZ and in turn, the size of the tensile zone [3, 29]. Additionally, the axial residual stresses measured by XRD and ESPI based hole-drilling showed a tensile region in the FZ and HAZ on the outer diameter of Ring 2; whereas Ring 1 exhibited compressive axial residual stresses at all surface and near-surface measurement points. This difference is thought to be attributed to the additional cosmetic pass on the outer diameter of Ring 2. The residual stress distribution in the FZ of both welded rings was found to be highly tensile throughout. This tensile zone was associated with a peak in microhardness and the observation of an almost entirely acicular martensitic structure in the FZ. Hardness within Ti-6Al-4V welds is typically directly related to the volume fraction of $\alpha'$, hence the highest values were recorded in the FZ [17]. This microstructural observation agrees with the work of Gao et al. [30] who confirmed that unlike TIG welded Ti-6Al-4V plates, the FZ in a Nd:YAG laser weld was formed of pure $\alpha'$ rather than $\alpha + \alpha'$. Additionally the observed isolated peaks and troughs in microhardness within the bulk are likely product of differing alpha/beta spacing, causing variations in boundary hardening, at those measurement points [20]. During welding, the local temperature in the FZ is sufficient to cause melting, which upon re-solidification results in a displacive martensitic transformation ($\beta \rightarrow \alpha'$) due to the surrounding bulk material and atmosphere acting as heat sink. The temperature gradient between weld and surface/bulk material causes the formation of thermal stress, which upon high cooling rates leads to the development of internal tensile residual stress, with surrounding regions of balancing compressive residual stress into the BM [20]. Thus, the temperature transition during martensitic phase transformation is likely to be the main source of tensile residual stress generation in the FZ. Additionally, the phase transformation itself may play some role in the evolution of residual stress during welding [24]. The $\beta$ (BCC) $\rightarrow \alpha'$ (HCP) transformation of titanium alloys is a shear transformation like that of other martensitic transformations in other materials (e.g. steels) and is therefore characterised by an increase in stored strain energy in order to accommodate an associated volume change. Thus, the observed martensitic microstructure in the FZ can be linked to the presence of tensile residual stresses in this region of the electron-beam welded components. The maximum tensile residual stress measured by the contour method, $+755$ MPa, was found to be located within a secondary HAZ identified near the outer surface of Ring 2 in the FZ. This is attributed to the secondary cosmetic pass applied to the ring, and coincides with the observation of ghost $\alpha$. Additionally, as shown by Owen et al. [31], an increase in ghost $\alpha$ volume fraction can lead to an increased hardness compared with $\alpha'$. This correlates well with the observed increase in microhardness results over the secondary HAZ, providing further evidence to support the observation of ghost $\alpha$. As ghost $\alpha$ is rare in comparison with $\alpha$, $\beta$ and $\alpha'$ phases, there is a relative lack of literature surrounding it. Nevertheless it has been observed in a number of welding techniques, both solid state and fusion based [32]. Attallah et al. [33] reported that under sufficiently high cooling rates, when the local temperature approaches the beta transus, $\beta_s$, there is insufficient time to permit the diffusion of alloying elements leading to their segregation in the transformed $\beta$, the product of which leads to the formation of lamellar ghost $\alpha$, rich in aluminium, with a semi-continuous structure and similar appearance to $\alpha_{gb}$. Le Biavant et al. [34] assessed the crystallographic orientation of ghost $\alpha$ in forged Ti-6Al-4V, determining a strong texture across macrozones. This texture was two orders of magnitude greater than the surrounding grains. The additive effect of this strong texture coupled with a highly tensile residual stress in this region will lead to accelerated fatigue crack initiation, reducing fatigue performance of the part [34]. The HAZ micrographs of both welded rings showed evidence of a transitional zone from the martensitic microstructure of the FZ to the characteristic bimodal $\alpha + \beta$ microstructure of the BM. This coincided with a reduction in tensile residual stress and microhardness levels as distance from FZ increased. The decrease in residual stress can be attributed to the reduction in the percentage of $\alpha'$ across the HAZ. However, there was a further reduction in residual stress past the point that the bulk microstructure was reached, with troughs of compressive residual stress noted beyond the microstructurally defined HAZ of both rings. The observation of similar highly martensitic microstructures yet differing phase morphologies in the near HAZ and FZ can be explained by the results of Greenfield and Duval [32], who state that the phase morphology of the near HAZ and FZ is significantly distinct due to increased solute segregation during solidification in the FZ. The unexpected protrusion of tensile residual stress observed in the BM of Ring 2 was further investigated by carrying out optical microscopy of a material sample from the identified region. A micrograph of this sample is provided in Fig. 13 showing the presence of elongated $\alpha_{gb}$ grains, over 400 $\mu$m in some cases, within the protrusion zone. The protrusion reaches far beyond the HAZ and is therefore not directly caused by the welding process and the microstructural changes induced by welding. Instead, it thought to be geometrically necessary stresses to balance the significantly high compressive residual stress on the inner surface induced by a slight difference in the thicknesses of the BM used in either side of the weld. Or, it may well be a product of the thermomechanical history during production of the base material prior to the EBM welding process. Significant effort is applied during manufacturing to ensure the breakup of these structures in an attempt to avoid deleterious effects on crack initiation and fatigue [35]. As these microstructural features coincide with the residual stress protrusion, it is highly probable that the two findings are interrelated. This further highlights the potential use of the contour method for the identification of problem areas in a manufactured part. ![Fig. 13. Optical micrograph of elongated $\alpha'$ extending from the primary HAZ of Ring 2.](image) 5. Conclusions Microstructural observations and microhardness measurements were successfully linked to the through-thickness residual stress distribution in Ti-6Al-4V electron-beam welds, as measured using a combination of the contour method, XRD and hole-drilling with ESPI. It was found that: - The FZ for both electron-beam welded rings was characterised by a highly tensile region of residual stress, corresponding to a microstructure which primarily consisted of acicular $\alpha'$ in prior $\beta$ grains; formed upon solidification. • A decrease in tensile residual stress from near to far HAZ was observed in both welded rings. This was also marked by a decrease in the volume fraction of acicular α’ and microhardness, as well as a shift towards the bulk microstructure. • The BM was found to principally exhibit compressive residual stress, and contained a bimodal microstructure of elongated α and α lamellae in a matrix of transformed β. • The transition from tensile to compressive residual stress upon increasing distance from weld centre correlates with the shift from a shear or displacive dominated transformation to a diffusional dominated transformation in the HAZ. • A secondary HAZ was identified near the outer diameter of the FZ of Ring 2 as a result of the application of a secondary cosmetic pass weld. This region possessed microstructural evidence of ‘ghost α’ formation in combination with exceptionally high levels of tensile residual stress. • Additionally, the contour method was used to identify an area of unexpected tensile residual stress in the BM which, upon further investigation, had microstructural dissimilarities compared to the remainder of the BM. These results may be used to advance the development of predictive models for weld behaviour, allowing for the optimisation of microstructure and residual stress in electron-beam welded Ti-6Al-4V components. Acknowledgements This work was supported by the Engineering and Physical Sciences Research Council (EPSRC). The authors wish to acknowledge Ben Saunders at Rolls-Royce plc for supporting an MEng Industrial Training Programme (ITP) module at The University of Sheffield, which initiated the study. The authors would like to thank Bradley Perry, Sam Robinson, Amit Samuel, Matthew Way and Sam Williams for their contribution to the study during the ITP. The authors would like to acknowledge the support provided by the Advanced Forming Research Centre (AFRC), University of Strathclyde, which receives partial financial support from the UK’s High Value Manufacturing CATAPULT. References
Accepted refereed manuscript of: DOI: [10.1016/j.ecolmodel.2017.06.008](10.1016/j.ecolmodel.2017.06.008) © 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ Pesticides and Bees: ecological-economic modelling of bee populations on farmland. Adam Kleczkowski¹, Ciaran Ellis¹, Nick Hanley², and David Goulson³ ¹ Faculty of Natural Sciences, University of Stirling, Stirling, Scotland, United Kingdom ² Dept. of Geography and Sustainable Development, University of St Andrews, St Andrews, Scotland, United Kingdom ³ School of Life Sciences, University of Sussex, Brighton, United Kingdom Corresponding Author: Adam Kleczkowski University of Stirling, Stirling, FK9 4LA, Scotland, United Kingdom Email address: ak@maths.stir.ac.uk Abstract Production of insect-pollinated crops typically relies on both pesticide use and pollination, leading to a potential conflict between these two inputs. In this paper we combine ecological modelling with economic analysis to investigate the effects of pesticide use on wild and commercial bees, whilst allowing farmers to partly offset the negative effects of pesticides on bee populations by creating more on-farm bee habitat. Farmers have incentives to invest in creating wild bee habitat to increase pollination inputs due to the contribution this makes to yields. However, the optimal allocation of on-farm habitat strongly depends on the negative effects of pesticides, with a threshold-like behaviour at a critical level of the impairment. When this threshold is crossed, the population of wild bees becomes locally extinct and their availability to pollinate breaks down. We show that availability of commercial bees masks this decrease in pollination services which would otherwise incentivise farmers to conserve the wild pollinator population. Indeed, if commercial bees are available, optimum profit may be achieved by providing no habitat at all for wild bees, and allowing these wild pollinators to go extinct. Keywords: pollination, pesticides, wild bees, commercial bees, ecological-economic modelling. 1. Introduction Globally, around three-quarters of food crops are at least partly dependent on insect pollination [1], and this share has been rising over the past 50 years [2]. Ensuring sufficient pollination of these crops will be challenging in the future, due to adverse pressures on the supply of pollination services. Wild insect pollinator populations are threatened by habitat loss, declines in foraging resources [3,4] and agricultural intensification [5,6], leading to population declines [6,7]. For some crops, honeybees are used to supplement or substitute wild pollinators, along with other commercial pollinators such as factory-reared bumblebees [8], although the majority of insect pollination for most crops is currently still delivered by wild pollinators [9,10]. However, whilst commercial pollinators can be substitutes for wild pollinators for many crops, [11,12], the use of commercial pollinators is not without risk. Honeybees have suffered losses in recent years due to the abandonment of hives (Colony Collapse Disorder), the impacts of the *Varroa* mite and associated diseases [13] and falling numbers of bee keepers in some countries [14]. If losses of honeybees occur over a wide area, there can be an impact on the supply of these insects for pollination services, which can lead to cost increases to farmers; for example, prices for honeybee hire for use on almond farms doubled between 2006 and 2008 in the US [15]. Given the risks associated with reliance on commercial pollination sources, maintaining viable wild pollinator populations is likely to be crucial for sustaining the production of insect-pollinated crops into the future [10,16]. Moreover, as we show in this paper, the availability of commercial bees can mask declines in wild pollinators past a local extinction threshold, threatening the supply of a wider set of valuable ecosystem services supplied by wild pollinators [39]. One of the factors implicated in the decline of insect pollinators such as bees is the use of pesticides. There is growing evidence of negative effects of commonly used insecticides on population- determining traits such as foraging rates and navigation in bees, on the overall growth and performance of colonies, and on the pollination services that they provide [17–24]. Awareness of this evidence has led to the temporary banning of the use on flowering crops of a widely used group of insecticides – neonicotinoids – within the European Union, but other insecticides are still widely used. Farmers of insect pollinated crops therefore face a dilemma, as one input (pesticides) is potentially dangerous to another (pollinators). One option, not investigated here, is to switch production to organic principles, and use zero pesticides. However, in the majority of global agricultural systems, abstaining from the use of all pesticides is not usually possible without substantial sacrifices in yields. Farmers must either attempt to reduce the impact of pesticides on wild pollinators, or increase the use of commercial pollinators which can be replenished year after year. Wild pollinators require habitat either off-farm or within the farm area. Although pollinating insects can forage over large distances, in intensive agricultural landscapes there is a decay in visitation of flowers by pollinators with increasing distance from the nearest habitat patch [25,26]. To offset this, farmers can encourage wild bees to nest within foraging distance of crops by providing nesting habitat and alternative foraging resources on the farm for when the crop is not in flower [3]. The effect of such interventions has been found to be strongest in intensively farmed areas [27] but depends also on the spatial location of bee- friendly habitat [28,29]. Hence, local or field-scale management practices may offset the negative impacts of intensive monoculture agriculture on pollination services to some extent [30]. In this paper, we develop an ecological-economic model to investigate the relations between two agricultural inputs, pollination and pesticides, and two sources of pollination with different characteristics; commercial pollinators, which can be replaced at a cost, and wild pollinators, which rely on a population being sustained within the farm area. Dedicating some of the farm area to sustain wild pollinators (eg by cultivating wild flower strips) is assumed to be costly in terms of foregone profits from maintaining a larger cropping area [31]. The model is parameterised using farm management data for strawberries, a relatively well-studied crop on which both wild and commercial bees are used. The neonicotinoid pesticide thiacloprid is also commonly used in strawberry farming to protect the crop from destructive pests such as capsid bugs. Our modelling framework is, however, generalizable to other cropping systems where conflict occurs between pesticides, crop area and the survival of wild bee populations. Our model improves on previous modelling attempts which have looked at either habitat considerations [28,29] or pesticide impacts [32] in isolation. In contrast, we combine these factors co-determining pollinator populations in a realistically-parameterised model which includes both economic and ecological behaviours. The model has three main linked components: the dynamics of the wild bee population; a production function which links bee populations and pesticide use to output, and farmers’ decisions over which inputs to employ, represented via a profit function. We consider a farm that produces a single crop; parameters are chosen to represent a typical soft-fruit production system [33,34]. The farm has an area $A$ which is divided into a wild bee habitat conservation area, $vA$, and a cropping area $(1-v)A$, where $v$ is the proportion assigned to the wild bee habitat (for modelling purpose we vary this between 0% and 70%). Honeybees and commercially reared bumblebees can both provide pollination services for fruit production. For simplicity we consider all commercial (non-wild) pollinators to have the characteristics of commercially reared bumblebees in terms of nest size and pollinating efficiency, and generate results for both a scenario where all pollinators are affected by pesticides, and a scenario where wild bees are affected but commercial bees are not. These choices correspond to extreme situations; in reality it is possible that commercial pollinators are affected, but to a lesser extent than wild bees, since efforts can be made to minimise chemical exposure to commercial nests such as shutting the bees inside the boxes before spraying, or only spraying before the placement of nest boxes. Wild nests, on the other hand, may be exposed to multiple sprays of insecticides. Although both wild and commercial bumblebee nests are vulnerable to disease, wild nests are more likely to have infestations of parasites at the time spraying occurs (commercial bee boxes should arrive at the farms free from disease and therefore only pick up infections and parasites from that point onwards), putting wild bees at increased risk of any interactive effects between parasites and pesticides [35]. For simplicity we are assuming that the farm is a closed system with regard to wild or commercial bees, so that bees are not migrating in from surrounding non-farmed habitat or leaving the farm. In reality bees do move between farms, which may buffer some of the more extreme effects predicted by our models (such as local extinction), and also means that bee populations supported by the actions of one farmer may benefit their neighbours. However, we do not capture the value of this external benefit in the model. We also assume no transfer of pesticides across the boundaries of the farm. **Wild bee population** The dynamics of the wild bee population is described in terms of $N(t)$ – a number of nests in a given year, $t$. This evolves according to equation (1): $$ N(t) = \min \left( R(N(t-1) - D(t-1)), K \right) $$ (1) where $N(t-1)$ is the number of nests at the beginning of year $t-1$, $D(t-1)$ represents the number of nests that die during year $t-1$. $N(t-1) - D(t-1)$ represents the number of live nests at the end of year $t-1$ that will reproduce in the following year. $R$ is the reproduction rate, i.e. the number of new nests that each reproducing nest produces in the following year. The carrying capacity, $K$, is calculated from the likely on-farm nesting densities of wild bumblebees, $N_w$, under the assumption that wild bees nest in the conservation area only, $K = N_w v A$. The simple, piecewise linear function, equation (1), captures the essential features of the nest dynamics – exponential growth for small numbers of nests, limited by a carrying capacity, $K$, for large numbers. We also considered alternative formulation of (1) with a logistic functional form; this produces very similar results, so they are not shown in this paper. Not all bumblebee nests will produce queens in a given year, and the likelihood of reproduction will depend in part on nest size. Pesticides can indirectly impact the likelihood of a nest reproducing by impairing the performance of foragers or increasing worker mortality and thus decreasing a nests’ ability to gather and process resources. These impacts can lead to increased colony failure, either through early colony death or by limiting the number of new queens produced $[19,20,23]$. Bryden et al. $[32]$ suggested a model in which the probability of nest death was inversely proportional to the number of foragers adjusted for pesticide impairments. Here we use an equivalent deterministic model in which a proportion $d_N$ of nests dies in year $t-1$ so that$^1$: $$D(t-1) = d_N \times N(t-1) .$$ Although in principle $d_N$ can depend on time, in this model we assume the constant probability of nest death following $[32]$, $$d_N = \frac{\mu}{\varphi + b_w}$$ $^1$ We also consider a stochastic equivalent of model (1), with nest deaths given by a random variable binomially distributed (with the maximum number of $N(t)$ and probability given by $d_N$): results are qualitatively similar to the ones presented here for the deterministic model. where $b_w$ is an effective number of foraging wild bees per nest, $b_w = F_w (1 - w_w)$ with $F_w$ being an average number of wild foragers per nest and $w_w$ the impairment factor due to pesticides. If no pesticides are used, or if pesticides are used but do not affect bees, $w_w = 0$; otherwise $w_w > 0$, reflecting for example, the effects on the navigational ability of honeybees which reduces the number of foragers which successfully return to the nest [18,19]. $\mu$ and $\phi$ are parameters determining the response of bumblebee population to pesticide (see Table 1). Equation (1) can thus be rewritten $$N(t) = \begin{cases} R \times \left(1 - \frac{\mu}{\phi + F_w \times (1 - w_w)}\right) N(t) & \text{if smaller than } K, \\ K & \text{otherwise.} \end{cases}$$ (4) The initial condition is assumed to be $N(t) = K$ for $t=0$. Under this assumption $N(t)$ will stay constant for $t>0$, as long as: $$R \times \left(1 - \frac{\mu}{\phi + F_w \times (1 - w_w)}\right) \geq 1$$ (5) and will decline exponentially to zero otherwise. In the following we assume parameter values such that condition (5) is always satisfied if and only if $w_w = 0$, that is, if there is no impairment due to pesticides. Pollination and yield. The single crop is pollinated by foragers originating from both wild and commercial nests. The total effective number of foraging wild bees is given by $B_w(t) = F_w (1 - w_w) N(t)$, whereas for commercial bees the effective number of foragers is assumed to be constant through time but proportional to the crop area, $B_c = F_c (1 - w_c) N_c (1 - v) A$. Here, $F_c$ is the average number of foragers per commercial nest, $w_c$ is the impairment of commercial bees due to pesticide use, $N_c$ is the number of commercial nests per ha, and (1−v)A (1−v)A is the area under the crop (here we assume that commercial nests will only be placed where the crop is located, not in the area set aside as on-farm wild bee habitat). As for wild bees, if no pesticides are used or are used but have no effect on commercial bees, then \( w_c = 0 \). Both wild and commercial bees are assumed to forage across the whole farm, over both crop land and the conservation area. The resulting effective density of foraging pollinators is then given by: \[ B(t) = \frac{B_w(t) + B_c}{A} = \frac{F_w(1-w_c)N(t) + F_c(1-w_c)N_c(1-v)A}{A}. \] (6) Production. The total farm production of a given crop in year \( t \) is given by \( Y(t) \times (1-v)A \) where \( Y(t) \) is the current yield (in tonnes per ha) which is assumed to be a step-wise linear function of \( B(t) \). We assume that without pollinators there is a set but low proportion, \( \alpha Y_{max} \), of a maximum yield (\( Y_{max} \)) that can be achieved. When pollination is fully supplied, the maximum yield is given by \( \gamma Y_{max} \) with \( \gamma \) being a maximum proportion of high quality crop [36]. For intermediate values of \( B(t) \) the yield per area in year \( t \) is given by: \[ Y(t) = Y_{max} \times \min(\gamma, \alpha + \beta B(t)) \] (7) where \( \gamma \) is the maximum proportion of good quality fruit in the case of “full” pollination, \( \alpha \) is the proportion of good quality fruits without bees and \( \beta \) is the incremental effect of bee visitation. The maximum attainable yield, \( Y_{max} \), depends on pesticide use and efficiency; we choose a higher value of \[ Y_{\text{max}}, Y_{\text{max,p}}, \text{if pesticides are used, and a lower value, } Y_{\text{max,nop}}, \text{if they are not.} \] As is the case for equation (1), in the light of limited available evidence this simple function captures the key elements of the yield dependence on supply of pollination services: an initial proportionality to the availability of bees and a saturation point at which additional numbers of pollinators have no further effect. **Farm economics.** There are two components to the profit function, the income from the sale of the crop and various costs, thus: \[ \Pi(t) = \text{Profit} = \text{Income} - \text{Cost of commercial bees} - \text{Pesticide costs} - \text{other costs}. \] The crop is sold at price \( p \) and with commission \( c_m \) so that the income is given by: \[ \text{Income} = p \times (1 - c_m) \times Y(t) \times (1 - v) A. \] Note that this implicitly accounts for opportunity costs associated with the crop considered here, as it includes ‘lost’ income due to diminished area under crop. Total costs for each year are the sum of variable (yield dependent) costs as well as the costs of wild flower seeds, pesticides and commercial bees. Harvesting and packaging costs are assumed to be variable and calculated per tonne. We divide the costs into three components. “Other costs” do not directly depend on the usage of commercial bees or pesticides, and are given by: \[ \text{Other costs} = C_h \times Y(t) \times (1 - v) A + C_a \times (1 - v) A + C_f \times A + C_s \times v \times A. \] where \( C_h \) is the cost per tonne (harvesting and packaging), \( C_a \) is the cost per crop area (planting, structures, fieldwork), \( C_f \) is the fixed cost per area incurred regardless of whether it is cropped on not (e.g. land lease costs), and \( C_s \) is the cost of maintaining the wild bee conservation area (mainly providing seed and opportunity costs other than growing the crop considered here). If commercial bees are used, there is an additional cost of buying commercial nests which is proportional to the number of commercial nests per ha and the area under crop, \[ \text{Cost of commercial bees} = C_c \times N_c \times (1 - v) A . \tag{10} \] In strawberry production, the main commercial bees used are bumblebees, which are purchased as disposable nests (sometimes called colonies) which last for up to 8 weeks. In other systems, farmers may rent honeybee hives for the duration of crop flowering. If pesticides are used, there is additional cost associated with their purchase, assumed to be proportional to the area under crop, \[ \text{Cost of pesticides} = C_p \times (1 - v) A . \tag{11} \] **Decision making.** Our focus is on the decision the farmer makes over the proportion of on-farm wild bee habitat, \( v \), which is driven by profit maximisation over an extended period of time. We consider two contrasting cases. For the main part of the paper we calculate the profit after a long period of time when the wild bee population has fully responded to the strategy implemented at \( t=0 \) (in practice we use 200 years), thus \[ \max_{0 \leq v \leq 1} \left( \lim_{t \to \infty} \Pi(t) \right) . \tag{12} \] This approach reduces dependency on (arbitrary) initial conditions and is equivalent to taking a long-term average without allowance for of any discounting of future costs and benefits. As an alternative we also consider an extension in which the profit is again calculated over a long time period, but with exponential discounting, so that \[ \max_{0 \leq v \leq 1} \left( \sum_{t=0}^{\infty} e^{-dt} \Pi(t) \right) \tag{13} \] where \( d \) is a discount rate. Note that the choice of \( v \) is made at \( t=0 \) and not re-evaluated and then changed afterwards. We analyse how the optimal choice of \( v \) and the resulting profit vary as pesticides are used or not, whether they affect wild or commercial bees, and whether the farmer decides to use commercial bees. **Parameters.** Although our model is generic for many cropping systems, we calibrated it to soft fruit production in the UK [33,34]. The numerical values for parameters used are listed in Table 1. \( K \) is calculated from the likely on-farm nesting densities of wild bumblebees. Nest densities will depend on the landscape type; around 11 to 15 nests per ha were found in non-linear countryside in a large scale survey in UK habitats, with higher densities in gardens and around linear features [37]. While actual densities will vary between locations, we assume that densities of 15 nests per ha can be found in on-farm habitat and that no nesting can occur within the cropped area. We follow Bryden et al. [32] in describing the effect of pesticide impairments on the dynamics of wild nests (Table 1). Costs of seeds, pesticides and bumblebee boxes are taken from a farm survey of 25 soft-fruit farms in Scotland [34]. Other production costs and prices per ha are taken from farm management data from the Farm Management Pocketbook(2016), [33], corresponding to raised-bed June-bearing strawberries. ### 3. Results We first analyse the optimal levels of conservation area provision, in the absence of pesticide use or any use of commercial bees. The effect of pesticide on wild bees in considered next and then provision of commercial bees is considered, with and without the negative impact of pesticides on their ability to pollinate. We use equation (12), i.e. the long-term profit maximisation problem without discounting; the extension, equation (13), is addressed below. RESULT 1: When no commercial bees or pesticides are used, profits are negative without on-farm wild bee habitat, and peak at low to moderate levels of its provision. Allowing for pesticide use shifts the yield and therefore the profit upwards, but the peak remains in the same position if pesticides have no adverse impact on wild bees. We first consider a case when pollination is provided by wild bees only. If pesticides are not used, or if they are used but do not impair the pollination ability of wild bees (so that the wild bee impairment \( w_w = 0 \)), then profits and the population of wild bees are stable over time (assuming that the initial number of nests is \( N(0) = K \)). Profits peak when the on-farm wild bee habitat proportion is between 10% and 20% (Fig. 1a) as profits depend on revenues made from the crop area, balanced against the loss through providing wild bee habitat rather than growing crops on the remaining area of land. At low levels of on-farm habitat provision, yield is limited by pollination, Fig. 1b, as \[ \alpha + \beta B(t) < \gamma \Rightarrow Y(t) = Y_{\text{max}} \times \left( \alpha + \beta F_w (1-w_w) N_w \right) v \] (14) (where we used the fact that \( B(t) = \frac{F_w (1-w_w) N(t)}{A} = F_w (1-w_w) N_w \) \( v \) with \( N(t) = K = N_w \) \( vA \); see Fig. 1c). Combining equations (6), (8) and (9) we see that for low values of the proportion of farm area under the crop, \( v \), the leading term in the profit function is of the form \( v(1-v) \), see the left hand side of Fig. 1a. When \( v \) reaches the critical level \[ v = \frac{\gamma - \alpha}{\beta F_w (1-w_w) N_w} \] (15) (i.e. when \( \alpha + \beta B(t) = \gamma \)) then yield becomes independent on the wild bee population, but total production and therefore profit decreases as the area under cropping decreases with increasing \( v \), as in figures 1a and 1b. Profits can be negative when there is no area of the farm used for wild bee habitat and yields are low due to pesticides not being used, Fig. 1a. When pesticides are used (still under the assumption of no adverse effect on wild bees), the profit function is shifted upwards (thick line in Fig. 1a), but this does not change the dynamics of wild bee population over time (Fig. 1c) or the optimal allocation of on-farm habitat. We note that if the initial density of the wild bumblebee nests, \( N(0) \), is lower than \( K \), the time projection of \( N(0) \) will increase towards \( K \). Profits in this case will also increase but in the long term the behaviour is the same as that discussed above. RESULT 2: When no commercial bees are used and wild bees are impacted by pesticides \( (w_w > 0) \), profits are lower and peak profits occur at higher level of on-farm bee habitat, as compared to the case without this negative impact. If the pesticide-induced impairment in pollination by wild bees is relatively small (eg. \( w_w = 0.3 \)), the wild bee population stays constant over time (assuming \( N(0) = K \), or increases until \( N(0) = K \) if \( N(0) < K \)), Fig. 2a. As a result, the yield is also constant, as in figure 2c. The corresponding profits are lower since they require a higher proportion of on-farm habitat to peak, see equation (15) and Fig. 3a, as more nests (and therefore more habitat) are needed to make up for the impairment of wild foragers by pesticides. These results are summarised in Fig. 4. Thus, with an increasing impact of pesticides on wild bees, there is a gradual increase in the optimal value of \( v \), as shown in figure 4a (compared to figure 3a). This is associated with the gradual decrease in the corresponding maximum profit, as shown in figures. 3a and 4b. Farmers can thus, to a degree, compensate for the adverse impact of pesticides on wild bees by increasing on-farm bee habitat, albeit it at an opportunity cost since the total land area is fixed. Wild bee numbers respond gradually to changes in the impairment as long as: $$w_n \leq 1 - \frac{1}{F_n} \left[ \frac{\mu R}{R-1} \phi \right];$$ \hspace{1cm} (16) When (16) is not satisfied, the behaviour of the population of wild bees switches from sustainability over long periods of time, $N(0) = K$, to decline over time, so that $N(0) \to 0$ with $t \to \infty$, Fig. 2b. As a result, there is not enough pollination potential and crop production declines; in our parameterisation this occurs for $w_n > 2/3 = 0.666...$, see figure 4. We choose $w_n = 0.67$ to illustrate this behaviour in Fig. 2b and d. The resulting profits are significantly lower than for $w_n < 0.666...$ (Figs. 2d and 4b). The optimal percentage of on-farm habitat changes in time and is initially ca. 50%, higher than when there is no impact of pesticides on wild bees. The qualitative change in the long-term dynamics of wild pollinators results in a threshold-like behaviour for the optimal proportion of on-farm habitat, $v$, Fig. 4a, and the associated maximum profit, Fig. 4b, both of which drop rapidly at the transition point, cf. equation (16). This points to very high sensitivity of the results with regard to the effects of pesticides on wild bee population as the threshold of $w_n = 0.666...$ is approached. RESULT 3: The speed at which wild bumblebees decline depends on the balance of nest death relative to nest reproduction. When wild bees are used as the sole pollination input, the likelihood of wild bee decline depends on the relationship between the impairment of foragers (and hence nest survival) and the reproductive capacity of the surviving nests each year (Fig. 2b). If the impairment is high enough, the density of nests declines exponentially in time as \[ N(t) = N(0) \times \exp(-rt) \quad \text{with} \quad r = -\ln \left( R \times \frac{\mu}{\phi + F \times (1 - w)} \right). \] (17) Thus, the characteristic time for the decline, i.e. the time needed for the population to decline from \( N(0) \) to \( e^{-r}N(0) \), is given by \( r^{-1} \) and sharply decreases when \( w \) increases, Fig. 5, independently of \( v \). However, the resulting decline in the profit can initially be slow (see an example in Fig. 6), effectively masking the decline in nest density (to illustrate this effect better, \( N_w \) is increased by a factor of 5 so that the resulting \( K \) is higher in Fig. 6 than in other figures). With higher levels of on-farm habitat, there are more wild bees per area of crop, and so there is a period where farms are over supplied with pollinators (this may have negative consequences in some crops as it could lead to too many fruits produced, see e.g. [36]). This continues until the wild bee population drops to a level at which pollination services become limited, at which point profits begin to drop (Fig. 6). Thus, the farmer might not have an incentive to reduce pesticide use until wild bee populations are too low to recover. RESULT 4: When commercial bees are used (and unaffected by pesticides), profits remain stable despite declines in wild bees, and are highest when on-farm habitat is low When commercial bees are used at the same time as wild bees, Fig. 3b and 4b, the highest profit corresponds to no on-farm habitat, i.e. \( v=0 \). The resulting optimal profit is higher than when pollination relies on wild bees only. The slight drop in the profit at higher values of \( v \) in Fig. 3b is due to the cost of buying in commercial bees. Profits remain stable throughout the projection period regardless of whether wild bee nests decline or not, Figs. 3b, 4b and 7a, with highest yields when no farm area is set aside for habitat. Thus, when farmers can buy-in pollinators which are unaffected by pesticides, and where such commercial bees can provide a perfect substitute for wild bees in terms of their pollination delivery, this acts as a severe disincentive to conserving wild bees or to reduce pesticide use. RESULT 5: When commercial bees are used and both these and wild bees are affected by pesticides, the optimal strategy is either to rely completely on commercial bees, or to provide a mixture of commercial bees and on-farm habitat for wild bees, depending on the level of impairment. When both commercial and wild bees are impaired by pesticides, profits generally change little if the impairment is low and equation (16) is satisfied, as shown in figure 4. The optimal area of on-farm habitat is zero, so all pollination is provided by commercial bees. If the impairment is increased (but (16) is still satisfied) it becomes profitable to invest in a mixture of wild and commercial bees, as shown by the dash-dot line in Fig. 3b and the intermediate range of $w_w$ and $w_c$ in Fig. 4a (here we assume $w_c = w_w$). This is also associated with a drop in optimal profit as compared to the case when commercial bees are unaffected by pesticides, Fig. 4b. The wild bee population remains steady for low impairment levels (if (16) is satisfied) and starts to decline when impairment becomes too high, resulting in the return to pollination based on commercial bees only, see the drop in Fig. 4a. Profits continue to decline with increasing impairment, as the reduced number of commercial bee foragers cannot provide the entire pollination service, leaving crops vulnerable to pollination failure (we assume that farmer does not change the provision of commercial bees over time: clearly, this assumption can be relaxed). However, the decline in profits at this point is smaller than if the commercial bees are not used, Fig. 4b, as the commercial bees still manage to moderate the adverse impacts of pesticides on the supply of pollination services. When the impairment is high and both commercial and wild bees are affected, profit declines over time unless $v=0$, Fig. 7b. Initially, when there is still sufficient number of wild bee nests, the optimal strategy is to invest in a mixture of wild and commercial bees, Fig. 7b. As wild bee nests die due to pesticide impairment, the farmer starts to rely on commercial bees only, even though they are also affected by pesticides. RESULT 6: If the decision maker discounts the future costs and benefits (i.e. follows equation (13) rather than (12)) in presence of current sufficient pollination supply by wild bees (i.e. $N(0) = K$), there is a region of the impairment values for which it is optimal to continue investing in the on-farm habitat, even if in the long term wild bees can become locally extinct. So far, we have assumed that the decision maker concentrates on the long-term outcome of the strategy, i.e. plans her use of pesticides, land allocation and the purchase of commercial bees according to equation (12). Very similar results are obtained if instead the decision maker uses the total profit over time without discounting future costs and benefits, that is optimises according to equation (13) with $d=0$; in this case the total profit is dominated by the long-term behaviour of $N(t)$ and consequently $Y(t)$ . In the more usual case where $d>0$, the outcome depends on the transient dynamics of $N(t)$. The optimal choice of $v$ is in this case similar to the case with no discounting for a wide range of $w_{w}$, figure 8(a), except just above the local extinction threshold (16). If wild bees are initially present, $N(0) = K$, it might take a long time until their population decays. Thus, rather than reducing their number outright by setting $v=0$ (as is the case for $d=0$), it is more profitable (in net present value terms) to allocate some area of the farm to temporarily keep the wild population even if it is declining over time due to pesticide effects. The danger of this solution is that in the long-term it still leads to the wild bee population extinction, even though this might take a long time to come about (as discussed above: figure 8(b)). **Discussion and Conclusions.** Pollination inputs are valued by farmers as they increase the quality and quantity of a range of important crops [38]. Using an ecological-economic model, we show that it can be rational for a farmer to allow wild bee populations on their land to decline, since this reflects a trade-off with the benefits of increased pesticide use. Moreover, the availability of commercial bees as a substitute for wild bees can effectively mask declines in wild bees approaching a local extinction threshold, and reduces the private value of wild bee conservation on farms. Whilst not considered directly here, there may also be lags in the response of insect pollinators to pesticide use, meaning that the market signal to farmers to change their management practice arrives “too late” to stop a permanent decline in pollinators. Since wild pollinators also generate ecosystem benefits for a wide range of wild plants beyond the farm from which society derives value [39], these three factors can all drive the supply of wild bees below the social optimum. In the modelling presented above, we consider the pollination services provided by a mix of wild and commercial bees which are inputs to a commercial crop. Farmers can “produce” more wild bees by allocating land to bee habitat, but this comes at an opportunity cost in terms of foregone profits from land allocated to cropping. Use of a third input, pesticides, contributes positively to profits through its effect on output, but negatively through any effects on bees. Farmers thus face a trade-off in the costs and benefits of pesticide use, where these costs go beyond the price paid for pesticides. If commercial bees are unaffected by pesticides, their small cost relative to other inputs (in our model parameterisation) means that profits are highest when commercial bees are used and little of the farm area is converted to on-farm habitat for wild bees. If wild bee numbers decline under pesticide pressure, profits can remain positive as commercial bee numbers can deliver the required pollination level to maintain yields and thus farm incomes. This is in contrast to the situation when wild bees alone are used for pollination and there is no option to use commercial bees. When only wild bees provide pollination, it is optimal for farmers to convert some of their crop land to wild bee habitat, a results which is in accordance with other studies [28,29]. How big an area of land is allocated to bee habitat will depend on crop prices and the productivity of land, both for wild bees and for crops. The outcome changes when commercial bees are impaired by pesticides along with wild bees. In this case, agricultural yields can be stable and high for a number of years and then fall suddenly, as wild pollinators decline past a particular threshold. High yields are maintained when there is an “over-supply” of pollinators, but fall after wild pollinators numbers decline to a level where overall pollinator numbers (the total supply of pollination services to the farm) limits yields. In practice, the relative impact of pesticides on commercial and wild bees will depend on farm management practices. Farmers can reduce the impact on commercial bees by shutting the hives or nest boxes when spraying takes place, although systemic pesticides, by design, are likely to persist within the plant for weeks after application meaning that bees will still be exposed through the ingestion and transport of contaminated nectar and pollen [7]. Wild pollinators cannot be shut inside nests while spraying takes place and so are more vulnerable, though some action can still be taken to avoid direct impact on wild pollinators such as spraying when wild bees are not active. If declines in wild pollinators are irreversible (e.g. as species become extinct), and if there is uncertainty over whether wild pollinators will be more beneficial in the future (e.g. as new crop varieties, more dependent on insect pollinators, are bred), then there is an option value to maintaining this natural capital for future use [40,41]. This option value is an additional economic rationale for conserving wild pollinators, even when there are commercial pollinators present. This value, however, will depend on the time-horizon and risk-aversion of the farmer, as farm profits may be stable for years before declines are evident. If farmers are present-bias, then there may be little private benefit to conserving wild pollinators for future crop production, implying that government interventions may be required to incentivise the creation of wild bee habitat, given the wide range of economic and ecological benefits which wild pollinators deliver [39,42]. The wild bee population modelled here will often in practice be made up of multiple populations of bee and non-bee pollinators such as hover-flies, wasps and beetles [11]. The presence of multiple pollinator groups can buffer the system from extinction [43,44], and we have not modelled this buffering capacity here. While different pollinators groups may respond in different ways to external pressure such as pesticide use, the effects are likely to be negative on all groups, and may be stronger on solitary bees and non-bee pollinators as these are often smaller in size and they are not buffered by living in a social colony with numerous expendable workers [21,45]. There is a benefit from maintaining multiple groups of ecosystem service providers as insurance against a fluctuating environmental conditions [46], implying a role for commercial bees in providing “financial insurance” against wild bee declines. On the other hand, commercial bees may contribute to wild bee decline, e.g. by introducing or spreading disease. Several simplifications made in the modelling procedure should be noted. We have assumed that all factors are deterministic. In reality key processes like pollination or be reproduction and death will be stochastic. We assume that all nests which reproduce produce a set number of queens which survive until the next year, since this simplifies the actual process which will rely on perhaps a larger number of queens being produced by successful colonies, who then may or may not mate, survive until the next year and establish a nest themselves. Overall success is likely to depend on other factors such as weather conditions and the level of disturbance, so the failure rate will vary substantially between years [32]. There is also evidence that pesticides can interact synergistically with diseases, poor nutrition and other chemicals, but this is not modelled either [22,35,47]. Moreover, if commercial bee keepers find that their bees are being adversely affected by pesticides, then supply may decline, leading to a future rise in the prices charged for commercial pollinator services. Our model describes a static permanent crop system which is grown every year with no change to agricultural practices over time. While this might be suitable for crops like strawberries which are grown every year, in many arable systems rotation will affect the year-to-year demands for services and resources available for pollinators. We also ignore feedbacks between the changes to yield and therefore profit and farm management strategies. In reality, farmers may respond to the decrease in availability of pollination services by changing the density of commercial nests or lowering the use of pesticides. We consider the bee population on the farm in isolation. Migration from outside will affect the rate at which the population changes over time; for example queens of wild bees are mobile so that farms with low or zero bee populations are likely to receive net immigration of nesting queens in spring. This may fill gaps in the resident population and protecting against local extinction, though the farm would then be acting as a sink, reducing the bee population on the surrounding farms. Similarly, foraging bees may fly several kilometres from their nest, spilling out from farms which have taken measures to provide habitat for them, and pollinating crops on neighbouring farms which have deployed no such measures. Discouraging such free riding may require financial incentives which reward those farmers who act to increase the stock of wild pollinators at the landscape level, whoever benefits. Our model also considers only two species, wild and commercial bees. In practice, different species will have different life patterns, different pollination ability, and will differ in their response to pesticides. The model presented here can be extended to multiple species, but will be even more difficult to parameterise. Moreover, other insect pollinator species could be more variable in their tolerance of weather conditions than the two species considered (commercial and wild bumblebees). If the commercial bees were honey bees, then these are less tolerant of certain weather conditions than (wild) bumblebees. In that case, a portfolio approach to management of pollinator resources on a farm would be more in favour of maintaining a mix of wild and commercial bees as a way of managing risk [48]. We have based model parameters on a specific crop, strawberries. As Keitt [28] concluded, the actual form of the production relationship between pollinators and profits is likely to vary across and within crops, depending on the yield response to both pesticides and bees, and the landscape in which the farmers are working. However, our model is applicable for a range of crops with similar or higher dependency on bees which also benefit from applications of pesticides, and which are grown within intensive agricultural environments, including other soft-fruits and almonds. We show that pesticide use is not only an externality, affecting wild bees in the vicinity of the farm, but part of an internal trade-off decision for farmers of insect pollination-dependent crops. In the presence of commercial bees, farmers have little incentive to support wild bees around their farms; although bees are important to crop yields, the availability of cheap substitutes means that high profits can be maintained in the short-term. This is despite a longer term risk of declining profits which can threaten the ability of farmers to maintain profits over time. Safeguarding farmland pollinators may therefore require monetary incentives to encourage the creation of on-farm habitat so that future pollination options are not reduced. The economic case for such incentives is strengthened when one also considers the non-market benefits of wild pollinators [39]. Acknowledgements We are grateful to the European Investment Bank (EIB) University Research Action Programme for financial support of this work through the ECO-DELIVERY project. Any errors remain those of the authors. The findings, interpretations and conclusions presented in this article are entirely those of the authors and should not be attributed in any manner to the EIB. We are also grateful to the anonymous referee for their comments. References Table 1: Key parameters in the model (modelled after soft fruit production). <table> <thead> <tr> <th>Parameter</th> <th>Interpretation</th> <th>Value</th> <th>Source/comments</th> </tr> </thead> <tbody> <tr> <td>$v$</td> <td>Proportion in conservation area</td> <td>0-0.7</td> <td>Key variable</td> </tr> <tr> <td>$A$</td> <td>Farm area</td> <td>100ha</td> <td>Assumed</td> </tr> <tr> <td>$R$</td> <td>Nest reproduction ratio</td> <td>4</td> <td>Incorporates the relatively small chance of queens mating and overwintering</td> </tr> <tr> <td>$N_w$</td> <td>Wild bees nesting density</td> <td>15</td> <td></td> </tr> <tr> <td>$N_c$</td> <td>Commercial bees nesting density</td> <td>4</td> <td>[20] gives estimates of 0.32-8.75 imported boxes per ha per year</td> </tr> <tr> <td>$\mu$</td> <td>Nest death parameter</td> <td>55</td> <td>[32]</td> </tr> <tr> <td>$\phi$</td> <td>Nest death parameter</td> <td>40</td> <td>[32]</td> </tr> <tr> <td>$F_w$</td> <td>Avg. number of wild foragers per nest</td> <td>100</td> <td>[34]</td> </tr> <tr> <td>$F_c$</td> <td>Avg. number of commercial foragers per nest</td> <td>100</td> <td>Same as $F_w$</td> </tr> <tr> <td>$w_w$</td> <td>Impairment due to pesticides, wild bees</td> <td>0 if no</td> <td>Key variable</td> </tr> <tr> <td></td> <td></td> <td>impairment; variable</td> <td></td> </tr> <tr> <td>$w_c$</td> <td>Impairment due to pesticides, commercial bees</td> <td>0 if no</td> <td>Key variable</td> </tr> <tr> <td></td> <td></td> <td>impairment; variable</td> <td></td> </tr> <tr> <td>$Y_{max,nop}$</td> <td>Maximum attainable yield when pesticides are not used</td> <td>11.5 tonne per ha</td> <td>Estimated from [33] as 50% of max yield</td> </tr> <tr> <td>$Y_{max,p}$</td> <td>Maximum attainable yield when pesticides are used</td> <td>23 tonne</td> <td>Max yield in [33]</td> </tr> <tr> <td></td> <td></td> <td>per ha</td> <td></td> </tr> <tr> <td>$\gamma$</td> <td>maximum proportion of good</td> <td>0.9</td> <td>[34]</td> </tr> <tr> <td>Parameter</td> <td>Description</td> <td>Value</td> <td>Source</td> </tr> <tr> <td>-----------</td> <td>-------------</td> <td>-------</td> <td>--------</td> </tr> <tr> <td>$\alpha$</td> <td>proportion of good quality fruits without bees</td> <td>0.35</td> <td>[34]</td> </tr> <tr> <td>$\beta$</td> <td>incremental effect of bee visitation</td> <td>0.0024</td> <td>Combined visitation and efficiency in [34]</td> </tr> <tr> <td>$p$</td> <td>Price per tonne</td> <td>3445</td> <td>[33]</td> </tr> <tr> <td>$c_m$</td> <td>Commission</td> <td>0.09</td> <td>[33]</td> </tr> <tr> <td>$C_h$</td> <td>Cost per tonne (harvesting and packaging)</td> <td>£1650 per tonne</td> <td>[33]</td> </tr> <tr> <td>$C_a$</td> <td>Cost per crop area (planting structures, fieldwork)</td> <td>£18700 per ha</td> <td>[33]</td> </tr> <tr> <td>$C_f$</td> <td>Fixed cost per area (land lease)</td> <td>£150 per ha</td> <td>[33]</td> </tr> <tr> <td>$C_s$</td> <td>Cost of maintaining the conservation area (mainly seed)</td> <td>£100 per ha</td> <td>[33]</td> </tr> <tr> <td>$C_c$</td> <td>Cost of commercial nests, per nest</td> <td>£60 per nest</td> <td>[33]</td> </tr> <tr> <td>$C_p$</td> <td>Cost of pesticide use, per ha of crop area</td> <td>£10 per ha</td> <td>[33]</td> </tr> </tbody> </table> Figure 1: Total profit (a), yield (b), and the number of wild bee nests, $N$ as functions of the proportion of on-farm habitat proportion, $v$. Thin line: no pesticides; thick line: with pesticides. No commercial bees are used and when pesticides are used, they do not affect wild bees. Parameters as in Table 1. Fig. 2: Total profit as a function of the on-farm habitat proportion, \( v \), for (a) no commercial bees, (b) with commercial bees but with small impact of pesticides, and (c) with commercial bees but with large impact of pesticides. Horizontal line represents zero profit. In (a), solid line corresponds to \( w_w = 0 \), dashed line to \( w_w = 0.3 \) and dotted line to \( w_w = 0.6 \). In (b) dotted line corresponds to no impact of pesticides on wild or commercial bees (\( w_w = w_c = 0 \)), and dash-dot line corresponds to \( w_w = w_c = 0.6 \) (solid line from (a) is redrawn for comparison). All other parameters as in Table 1. Fig. 3: Dependence of (a) and (b): the number of wild bee nests $N(t)$, and (c) and (d): total profit, on the on-farm habitat proportion, $v$ and time (between 0 and 200 years), when pesticides are used but commercial bees are not. In (a) and (c), there is no effect of pesticides on wild bees, $w_w = 0$, and in (b) and (d), $w_w = 0.67$. Other parameters as in Table 1. Fig. 4: Dependence of the optimal on-farm habitat proportion (a) and the corresponding total profit (b) on the wild and commercial bee impairment due to pesticides. Thin solid line corresponds to the case without commercial bees; dashed line corresponds to the case with commercial bees, but with no impairment of their performance, $w_c = 0$. For the thick solid line, commercial bees are used and affected by pesticides in the same way as wild bees, $w_c = w_w$. Other parameters as in Table 1. Fig. 5: Dependence of the characteristic time of decay for the wild bee nests, $r^{-1}$ (i.e. time needed for the population to decrease by a factor of $e^{-1}$, in response to the impairment, $w$). Fig. 6: Examples of time projections for profit over 200 years. Pesticides are used, but no commercial bees; high impact of pesticides on wild bees ($w_w = 0.67$). For illustration, the carrying capacity for wild bees is doubled so that the effect of overpollination is more pronounced. Solid line: $v=0.22$ (optimal), thick line: $v=0.52$, dashed line: $v=0.7$. Other parameters as in Table 1. Fig. 7: Comparison of dependence of the profit on time and on-farm habitat proportion for the case when pesticides and commercial bees are used and pesticides strongly affect (a) wild bees only ($w_w = 0.67$, $w_c = 0$) and (b) both wild and commercial bees ($w_w = w_c = 0.67$). Other parameters as in Table 1. Fig. 8: Dependence of the optimal on-farm habitat proportion (a) and the corresponding long-term number of wild bee nests, $\lim_{t \to \infty} N(t)$, (b), on the wild bee impairment due to pesticides, for different values of the discounting factor, $d$. Thin line: long-term optimal solution, using equation (12); thick line: model with discounting, equation (13), with $d=0.05$; dashed line: equation (13) with $d=0.1$. Only the case with no commercial bees is considered. Other parameters as in Table 1.
Annie Burman* Paint Pigment on Epigraphic Squeezes: A Case-Study from the Etruscological Collections of Olof August Danielsson https://doi.org/10.1515/etst-2022-0017 Published online March 8, 2023 Abstract: The practice of wet squeezing as a means of creating epigraphic facsimiles was widespread during the 19th and 20th centuries, but often negatively impacted the original inscriptions, particularly in cases where paint pigment was present. Depending on the precise method used, the pigment may transfer from the original to the squeeze. This article presents a case-study of four such squeezes made by Swedish Etruscologist Olof August Danielsson in 1886 of a funerary tile from Chiusi, as part of the preparatory work for Corpus Inscriptionum Etruscarum. This material makes it possible to study epigraphic polychromy in cases where pigment on the original has been damaged through squeezing. In addition, it illustrates how squeezes can give insight into the history of individual objects, as the squeezes, which show both the carving and the paint, cast light on the various proposed readings of the tile’s Etruscan inscription (CIE 1973/ET Cl 1.1478). Keywords: Etruscan, epigraphy, polychromy, squeezes, funerary tiles 1 Introduction Squeezing (sometimes referred to as wet squeezing) is a method by which a negative facsimile of a carving is created in paper. Likely developed already in the sixteenth century, it became widely used by epigraphists during the nineteenth century. Still 1 In 1548, Jean Matal described how Antoine Lafréry made a facsimile by filling the letters of a bronze tablet with ink, covering it with a paper and piling sand on top of it to force the paper into the letters (Stenhouse 2005, 50–53). While not identical to later wet squeezing, it is a clear predecessor. The squeezes made by Italian nobleman and antiquarian Raffaello Fabretti in the seventeenth century look more like the squeezes of the nineteenth century (Kragelund 2003). Another early example of wet squeezing were the facsimiles made by Carsten Niebuhr of inscriptions at Persepolis in 1765, which would contribute to Friedrich Grotefend’s decipherment of cuneiform (see Simpson 2007, 343; Nagel 2010, 165–166; Mousavi 2012, 108–10, 120–1). *Corresponding author: Annie Burman, Department of Linguistics and Philology, Uppsala University, Uppsala, Sweden, E-mail: annie.burman@lingfil.uu.se. https://orcid.org/0000-0003-2876-729X Open Access. © 2023 the author(s), published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. today, squeezing is taught to students of epigraphy. While there are still scholars who make use of it, squeezing has generally fallen out of favor. In the 1940s, photography was seen as a complement to squeezing, but the development of more reliable cameras (in particular digital cameras which cut out the cost of development and, later, the advent of smartphones, which makes it possible to take high-quality photographs without having to carry heavy camera equipment) likely contributed to squeezes being phased out. However, the impact of squeezing on the inscriptions has also been a concern. Many institutions housing inscriptions, such as the Athens Epigraphical Museum and the British Museum, no longer allow squeezes to be made of the inscriptions in their collections. A squeeze is made by placing a piece of wet paper over the inscription, which is then beaten into the carving with a special brush. W.M.F. Petrie’s description of the process captures how vigorous it could be: [The paper is] gently beaten with a spoke-brush until it is pushed into the hollows [of the stone]. [...] Finally, a severe beating is given to the whole, as violent as can be done without tearing the paper. The paper should be pulped on the stone, and driven into every crack and porosity; using a second, and even a third, sheet to bind it together. The pulp in the hollows should be kneaded in with the sharp edge of the brush-back, using the whole weight of the body to force it home. It is no surprise, then, that originals could incur damage through the process. One of the main issues is the impact squeezing has on any paint present on the inscription. The risks to pigment have been known for some time. When describing the damage done to Egyptian wall-paintings in her 1878 travelogue, Amelia Edwards describes how “the student of Egyptology, by taking wet paper ‘squeezes’, sponges away every vestige of the original colour.” Petrie points out that “on all coloured work, and many kinds of tender stone, wet squeezing is a crime [...]. Fatuous tourists and brazen students have wrecked innumerable monuments by wet squeezing”. At the time Petrie was writing, wet squeezing had been prohibited in British-controlled Egypt. It is not a coincidence that these observations came from writers whose focus was ancient Egypt, where polychromy was not viewed with the same suspicion as in relation to Greece and Rome. This chromophobia, as it has sometimes been called, goes back to Johann Joachim Winckelmann, who argued that “the essence of beauty consists not in colour but in shape” and that “a beautiful body will [...] be the more beautiful the whiter it is.” Remnants of paint on Greek and Roman marble sculptures and reliefs would often be removed, sometimes with chisels. The same aversion to color has not been as present in the field of Etruscology, but much of the research, like the recent study of polychromy in Greco-Roman sculpture, has focused on figurative art. Polychromy in epigraphy is overall still under-researched. There are two stages of the squeezing process which pose a risk to pigments. The one that most critics focus on is the initial cleaning of the stone. Petrie describes that before a squeeze can be made, “the stone must be thoroughly cleaned and soaked”. Almost 80 years later, Gordon instructed that “one cleans the inscribed surface with a small cleaning brush, with or without water, so as to remove all dirt, incrustations of lichen, etc., and (modern) paint”. He goes on to claim that this will not damage any ancient minium – red lead – present on the stone. Numerous scholars see this as the point at which the worst damage is done, envisioning any pigment being brushed off the inscription or discarded along with the water used for washing. Although the risk to pigment through initial cleaning is considerable, there is also evidence that the actual act of squeezing impacts it. When this occurs, the pigment is indeed removed from the original, but it is not lost. It is instead transferred to the paper squeeze. While this has been mentioned in passing in relation to squeezes of material from Egypt, Mesopotamia and Persia, it has never been the subject of any in-depth research.20 This article considers pigment transfer during the squeezing process through a case-study of four squeezes of an Etruscan funerary tile. The squeezes were made by the Swedish philologist Olof August Danielsson in 1886, and are currently kept in his archive at the Uppsala University Library as part of a squeeze collection comprising 46 large boxes.21 2 The Four Squeezes In 1884, Danielsson and his colleague Carl Pauli, a German scholar and schoolmaster, agreed to start work on a new Etruscan corpus. Pauli had had the ambition to create a corpus for Etruscan inscriptions in the mould of the CIL for several years. It had initially been planned as a joint venture between him and Wilhelm Deecke, with whom Pauli had become acquainted through his championing of Etruscan as a non-Indo-European isolate. Together, they submitted a request for funding to the Berlin Academy in 1881, but it was denied. A year later, their collaboration and friendship came to an abrupt end when Deecke retracted his statements on the classification of Etruscan. The following year, Pauli came into contact with Danielsson, who had been awarded his doctoral degree only three years prior. After some correspondence, they agreed to start work on what would eventually become the Corpus Inscriptionum Etruscarum.22 Pauli had already conducted autopsies of Etruscan inscriptions in Leiden in 1883, but for the project to be truly successful, the editors would have to travel to Italy. Pauli and Danielsson arrived in Italy in November 1885. Pauli returned to Germany before the end of the year. Danielsson continued his epigraphic field-work alone until July 1886, travelling around Italy and making notes, sketches and, most importantly, squeezes. The collection is estimated to contain around 9000 squeezes. As itemization of the collection is still ongoing, the first nine boxes of 46, containing almost 1900 squeezes of 20 e.g. Parkinson 1997, 223; Thavapalan et al. 2016, 203; Aloiz et al. 2016; Booth 2018, 206, 234, 265. Nagel (2010, frontispiece, 147–8, 256) includes photographs and microscopic images of blue paint residue on squeezes of Old Persian inscriptions, as well as describing one case of Egyptian blue being positively identified on a squeeze. 21 See Nachmansson 1931 for a biography on Danielsson, and Wikander and Wikander 2003, 27–35 for an overview of the collection. inscriptions with CIE numbers up to 2200, will be used as a sample. Of the inscriptions CIE 1–2200, a total of 1365, around 62%, are represented by facsimiles in the collection. Wet squeezing is by far the most common technique, representing 90% of the collection, but other methods like tracing and rubbing were also used. Most of the facsimiles, over three quarters of the sample, were made by Danielsson. The facsimiles collected as part of the CIE project were carefully marked up to facilitate organization. Those made by Danielsson, both in 1886 and during later trips, contain two types of annotation: notes written in pencil on the squeeze and a series of labels with relevant information written in ink. Based on analysis of the sample squeezes, it is possible to make an informed guess how the process occurred. Danielsson would autopsy an inscription, make notes and make one or more squeezes. At some point after the squeeze was dry, he would add information in pencil along the edges where the paper had not been subject to the squeeze brush. On some squeezes, these notes appear to have been written against an uneven surface. As this would not be the case if he had a desk or even a book to lean the squeeze against, it seems likely that he made these while still in the field, resting the squeeze against some nearby object that was reasonably (but not completely) flat, possibly one of the objects he had just autopsied. The first of the four squeezes that will be discussed further on in this article, 1393, is marked in the typical way: “Chiusi 100 16/IV 86” – the city where the squeeze was made, a number and the date of the squeeze’s creation. The number 100 is in reference to the inscription rather than the squeeze, as can be seen in squeeze 1396, where it reoccurs, modified by a Roman numeral II. Often, though not in this case, 23 These boxes are 37:1:1–3, 37:2:1–3 and 37:3:1–3. Itemization is done in preparation for digitization and dissemination through the Alvin digital repository. A small number of squeezes and notebooks are already available, see http://urn.kb.se/resolve?urn=urn:nbn:se:alvin:portal:record-6916. 24 Of the 1900 facsimiles, the creators of 1867 have been identified. Danielsson is responsible for 1429 of these. Pauli, who served as head editor, only created 243. The remaining facsimiles were made by Pauli’s children, particularly his son, and scholars who sent material to the CIE editors. Of the squeezes with no named squeeze-maker, many bear notes made in Danielsson’s handwriting, making him the likely creator. 25 The squeezes that are the focus of this case-study will be referred to by their squeeze numbers in the text. The full archive references, as well as hyperlinks to digitized versions of the squeezes, are provided in the footnotes when the squeezes are discussed individually below. As Pauli’s numbering of squeezes is sometimes inconsistent, with numerous squeezes being given the same squeeze number, I will refer to squeezes in the footnotes in the following way: Box number/Inscription number/Squeeze number (as given on the squeeze). 26 This is only one of many ways in which Danielsson would mark squeezes of the same inscription (or part of inscription). Sometimes, he adds Doubl. (e.g. Uppsala University Library, O.A. Danielsson 37:1:3, squeeze 37:1:3/509/1859) or Doublette (e.g. Uppsala University Library, O.A. Danielsson 37:1:3, squeeze 37:1:3/627/1275), “duplicate”, but it seems that in this case, he did not consider this other squeeze a duplicate. At other times, he will mark them in other ways, such as besser Copie “better Danielsson would add the letter “D.” after the date, to identify himself as the squeeze-maker. This goes back to when Pauli and Danielsson made squeezes together, and would mark them with their final initial. Danielsson would often add a reference to the *Corpus Inscriptionum Italicarum* (CII), the most commonly used corpus for Etruscan at the time. These references are formatted in the same way as those found in CIE, with “Fa.” used to refer to Ariodante Fabretti’s main volume of CII and three supplements, and “Ga.” used to refer to Gian Francesco Gamurrini’s appendix. This implies that Danielsson had these volumes with him on his trip. As these volumes were quartos, they were far more portable than many other corpora. However, the uneven quality in the handwriting is generally not seen in the CII references, indicating that these were not added in the field. The squeezes were sent to Pauli, who equipped them with labels on the obverse of the squeeze. This sequence of events is strongly implied by the fact that it is only ever Pauli’s handwriting on the labels. As chief editor, he was the one who organised and used the squeezes, making it likely that he designed the system himself. Five different labels were used, with specific designs and inks reserved for each piece of information. The labels recorded the following: - Ancient or modern location, corresponding to the chapter or subheading under which the inscription would appear in CIE. - Information about the creation of the squeeze, including when, where and by whom it was made. - References to previous editions. - Inscription number, frequently (but not always) the same as the CIE number. - Squeeze number. Squeezes were numbered in the order they were made, based on field-notes where necessary. Thanks to the information on the squeezes as well as Danielsson’s notes, we can piece together the process of autopsy, note-taking and squeezing. Danielsson arrived in Chiusi on the 13th of April, 1886. At this point, he would have been an experienced squeeze-maker, having spent almost six months with this as his main task. If Danielsson kept a diary, it has not been preserved, but the notes for much of the *CIE* field-work are kept in the Uppsala University Library. On the title page for the notes of Chiusi, Danielsson made a note about the weather conditions. It had been windy, so the squeezes of inscriptions displayed outdoors in the Succursale had *etwas schlechter geworden*, “turned out a little worse”. He also complained of the humidity inside the Chiusi museum, which had complicated the squeezing work. It was inside the museum that the tile at the heart of this case-study was located. Funerary tiles were in use in the Clusine territory from the third century BCE to the second half of the first century BCE. Their purpose was to seal the niches where the burial urns were kept in *dromos* graves. The provenance of this particular funerary tile (Figure 1; museum inventory number 176, national inventory number SA FI65808, TM 150650/CIE 1973/ET2 Cl 1.1478) is unknown. It is made from kneaded clay and measures 61.5 cm in height and 45 in width at its widest point. The vertical sides of the tile are raised, providing a border for the epigraphic space. The tile bears two lines of text in the Clusine alphabet (the reading of which will be discussed below), seemingly written by a layperson, something that was standard for funerary tiles. While most funerary tiles are unadorned, this tile features a carving of two anchors. Each anchor has a ring both on the stock and at the crown, a feature it shares with the mosaic anchor in the House of the Anchor in Pompeii (VI 10.7) as well as the iron anchor found in Lake Nemi. Gamurrini (CII App. 181) gave the following reading: \[ lr\theta i (\text{i})austine \] \[ lati caunei \] Generally, Danielsson would dedicate only a few lines to each inscription in his notebook, often covering five or more inscriptions on each page. The notes on this tile, however, takes up two thirds of a page. The reason for this is that Danielsson could not reconcile Gamurrini’s reading with what he was seeing on the tile. Danielsson made four squeezes, one covering the full inscription and three featuring various details (referred to by his notes as *Specialabklatsche*). The areas --- 30 Danielsson 1886, 9. 31 See Benelli 2010, 123–4. 32 Soprintendenza alle antichità d’Etruria, catalogue card 65808. I am indebted to Fabrizio Vallegonga for providing me with documentation concerning the tile as well as numerous photographs. 33 One other tile (CIE 2864/ET2 Cl 1.2476) with a similar carving survives, though featuring only one anchor. The anchor on this tile is very similar to the anchors on the tile under discussion in this article, down to details such as the way the shank extends into the upper ring. It is tempting to posit some relationship between these two tiles, but with no known provenance, this would only be speculation. 34 Speziale 1931, 311, pl. i–ii. See Nautical Archeology Society 2008, 200 on terminology relating to anchors. covered by each squeeze are given in Figure 2. Generally, Danielsson would only make one squeeze per inscription. Analysis of the sample shows that of the 867 inscriptions represented, only 22.8% had more than one facsimile made. Inscriptions that were copied more than twice make up only 6.2%. Making four squeezes, particularly where the original was small enough to capture with only one squeeze, was therefore out of the ordinary. It appears that Danielsson made notes and squeezes simultaneously, as the notes contain one sentence in Swedish which is now sandwiched between two lines that follow on one another, implying that he wrote this below what he had written before, and then had to write around it. Considering **Figure 1:** Funerary tile kept in the Museo Nazionale Archeologico in Chiusi. Photograph by Fabrizio Vallelonga. Used with permission from Ministero della Cultura – Direzione regionale Musei della Toscana – Firenze. the choice of language, the crossed-out instruction and the fact that it is disconnected from the rest of the text, it seems likely that this was a note to himself.35 Rev[idera:] Sista raden kan göras om och ny afkl[appning]36 Revised: the last line can be redone and a new squeeze All three additional squeezes focus on that final line. When he finally solves the issue, there is a clear note of frustration in his notes: 35 It is possible that Pauli could read Swedish, as he contacted Danielsson after reading his review of Pauli's Altitalische Studien in the Swedish-language Nordisk Revy (Danielsson 1883, see Wikander and Wikander 2003, 19). However, he may simply have been aware of the review and the fact that it was positive. Considering that the sentence in Swedish in Danielsson's note would be of little use for Pauli in Germany, the more reasonable explanation is that it was written as a reminder to himself. 36 Danielsson 1886, 90. 37 Danielsson 1886, 90. I could have been spared all this back and forth, several special squeezes and quite the headache if I’d just had the sense and courage to wash off the remains of the red paint as well as the worst of the dirt. [It is] now entirely clear that the second row [reads] laði cauśine The reading on which Danielsson settled is the one that appears in CIE (number 1973): \[ \text{laði : cauśine} \] \[ \text{laði cauśine} \] The inscription was not autopsied in preparation for either edition of *Etruskische Texte*, and Rix and Meiser give largely the same reading as Pauli and Danielsson (ET Cl 1.1478). The only difference is that they read the word-divider as a single punct (rather than a dicolon) and put the second line in curled brackets to indicate that it is superfluous. They also indicate that *cauśine* in the first line is a mistake for *cauśline*, a gentilicium that occurs elsewhere in the epigraphic record.38 Having looked at Danielsson’s process, let us now turn to the squeezes themselves. Squeeze 1393 (Figure 3)39 covers the whole inscribed area, measuring 26.6 cm in height and 44.5 cm in width. The reverse of the off-white squeeze is of particular interest. A considerable amount of red pigment from the inscribed text and the anchors has transferred onto the squeeze paper. It is worth asking how we can know that the red pigment was indeed transferred from the original. There are, however, numerous reasons to be certain that this is a case of paint transfer. While some epigraphists were in the habit of touching up their squeezes using crayons, tracing the letters on either the reverse and the obverse, Danielsson appears not to have done this.40 His notes mention the presence of red paint as well as dirt on the tile. Two other details concerning squeeze 1393 show that the red is definitely transferred from the original. Firstly, the reverse of the squeeze bears yellowish discoloration, particularly around the carvings, where Danielsson would likely have directed most of his blows with the squeeze-brush. In the museum catalogue, the clay of the tile is described as *giallino* ‘light yellow’, which indicates that this discoloration is in fact residue from the object itself. --- 38 The name Causlini/Causlinei occurs as a gentilicium on two ossuaries (CIE 970/ET² Cl 1.1029, CIE 1974/ET² Cl 1.1479), one ossuary lid (CIE 1971/ET² Cl 1.476) and one additional funerary tile (CIE 1972/ET² Cl 1.1477), and as a metronymic on two funerary tiles (CIE 1316/ET² Cl 1.229, CIE 1317/ET² Cl 1.130) and two ossuaries (CIE 971/ET² Cl 1.1030, CIE 972/ET² Cl 1.1696). Although it is likely that there is some relationship between the commemorated individuals, none can be determined for certain. 40 This practice is similar to but more disruptive than the “marked squeezes” described by Dow (1942, 324). It can be seen in the squeezes made by Runologist Hjalmar Kempff of Runic inscriptions in Norway (Uppsala University Library, archive of Hjalmar Kempff, NC 652). More sediment, the color of yellow ochre, was caught in the adhesive Danielsson used to secure the paper to the tile, visible in both upper corners of the squeeze. Secondly, there is a second instance of paint transfer. In the middle of the squeeze, just above the second word of the first line, one can make out the mirrored numeral “28”. The evenness of the numerals indicate that they were made with a stencil or stamp. The orientation is due to the fact that squeezes will always give a mirror image of the original (as can be seen by the fact that the Etruscan writing, originally right to left, runs from left to right in all the squeezes). Danielsson’s notes again provide an explanation. Along with his own numbering of the squeeze, 100, he has added “Mus. 28”, indicating that this was the museum catalogue number. It is no longer in use as the museum collection was recatalogued and renumbered when the museum was moved to its current location in 1901.41 A similar way of marking the objects was used after the renumbering, as can be seen by the current catalogue number 176 on the squeeze in Figure 1. Squeeze 1394 (Figure 4),42 which, like squeeze 1393, was made with Danielsson’s standard paper, focuses on the beginning of line 1 and the whole of line 2. There are faint traces of red pigment in many of the letters, particularly in the letters <θi: ca> in line 1. It can also be seen in <laθi> in line 2. There are splotches of yellowish --- 41 Fabrizio Vallelonga, pers. comm. discoloration, particularly around the anchor, but they are far less noticeable than on squeeze 1393. In the top-right corner, the curve of the numeral <8> can be made out, but with difficulty. Squeeze 1395 (Figure 5)\(^{43}\) was made using two pieces of very thin paper placed on top of one another, rather than a single sheet of thicker paper as with the other squeezes. This method makes smaller details more obvious. This squeeze is only 5 cm high but 29 cm wide and covers the second line and parts of both anchors. Although the yellowish tone of this paper makes it harder to see, upon close inspection evidence of paint transfer can be found. There are small, isolated patches of discoloration from the tile above the <l>, below the <i> and to the right of the anchor ring. There is red pigment in the letters, particularly the sequence <laθ> and the <u>, as well as the shank of the anchor, but it is far more scattered than in previous squeezes. The final squeeze, 1396 (Figure 6),44 measures 38.5 cm in width and 15.5 cm in height. Although it covers a smaller area than the first squeeze, it depicts both lines of the inscription, as well as the upper part of both anchors. In one of the three points of adhesive used to hold up the squeeze, some sediment has become stuck, but the squeeze itself has almost none of the discoloration the other three have. Yellow remnants of the clay are seen primarily under the second line, in an area which was not covered by squeeze 1395 and has therefore been subjected to Danielsson’s ministrations less than the rest of the epigraphic space. Elsewhere, the discoloration only appears as specks, such as just under the <u> and in the area above <larθi>. The red pigment that was so prevalent on squeeze 1393 is all but gone. The only visible remnant is a speck of red in the <θ> in line one. All that remains of the museum number is the top curve of the <2>, just above the san in line one. During the course of the creation of these four squeezes, we can see how less and less pigment is being transferred, as the amount of pigment on the original is decreasing. Considering how squeeze 1393 looks, as well as Danielsson’s comment about not having had “common sense and courage” to clean the inscription, it is unlikely that the tile was washed before the first squeeze was made. It is naturally possible that Danielsson washed or otherwise cleaned the tile between making the --- **Figure 6:** Reverse of squeeze 1396. squeezes, but even if that was the case, we can see how the squeezing removes more and more pigment. Very little, if any, red pigment remains on the original. Microscopic remnants may still survive, but this would require a more in-depth study. The black numerals <28> are very faint, only visible if one knows exactly where to look for them. The new catalogue number, 176, was painted onto an area of the tile that does not bear any carvings. These squeezes show the detrimental effect that the process has on paint pigments, but they also provide valuable insights. In the words of Booth: “Considering pigment transference is one of the reasons that squeezes have such a poor reputation as a recording method, it is time to turn that negative into a positive academic feature.” 45 When taken together with Danielsson’s notes, the squeezes show the process by which the CIE editors conducted their work, as well as the work of previous corpus editors. Squeeze 1393, which contains most of the paint pigment, shines a new light on Gamurrini’s reading and line-drawing (Figure 7). Although Gamurrini says he autopsied most of the inscriptions included in the Appendice, it is unclear whether this tile was one of them. 46 Unlike in other entries, he does not give a date of autopsy. Whatever the case, the line-drawing is obviously based on the painted words. The <a> in larrθi, which is written above the line, was not filled in with paint in squeeze 1393, making it harder to make out. It is completely missing in both Gamurrini’s line-drawing and reading. The name causine in line two has been painted as caunei, which is again what Gamurrini gives. 47 This raises the question when the paint was added. Possible options are: (1) The paint is ancient. (a) It was added to correct a mistake in the carving, i.e. the carver mistakenly carved causine when the intended name was caunei, and caunei was added using paint. (b) It was added by someone who did not know the name of the deceased (and therefore misread the name), but who was still familiar with the Etruscan script. (2) The paint is early modern or modern and was added at some point after the tile was found (made by someone with enough experience of Etruscan epigraphy to know that women’s gentilicia end in -el). 45 Booth 2018, 206. 46 Gamurrini 1880, vi. 47 The person who made the line-drawing has drawn the <c> in line 1 as partially damaged, and when presented this way it could be read as a <f>, as Gamurrini does. However, there is no basis, whether in the painted letters or the line-drawing, for Gamurrini’s reading lati in line 2. Both show a clear <θ>. (3) The paint is a combination of ancient pigment and early modern/modern touch-ups. Option (1a) is made less likely by the fact that *cauštine* is not corrected to *caušline*. It also requires that the tile commemorates two people, rather than just one.\(^{48}\) Considering the carver’s tendency of leaving out letters, e.g. *laθi* for *larθi*, it seems likely that both lines refer to the same person. Option (1b), that the paint was added in antiquity but not in conjunction with the carving, is more likely than (1a). We do not know what type of upkeep was done on Etruscan graves, and whether the tiles may have been (re)painted by later generations. If this occurred, it is possible that the mistake was made then. As Etruscan women kept their gentilicia and their children were given the gentilicium of the father, descendants would not have had the same name as a female ancestor. Descendants may also not have been certain whether the tile commemorated one \(^{48}\) Gamurrini (1880, 23) believes the tile commemorates two women. The addition of curled brackets in both editions of *Etruskische Texte* around the second line, indicating it is superfluous, indicate that Rix and Meiser believe it commemorates a single woman. person (whose name was repeated twice) or two people (with the same praenomen but different gentilicia). The fact that the misreading in line two, which led to the carved cauśine being painted as caunei, involves a san may point to the person responsible not being familiar with the Etruscan script. Early modern scholars would often assume ⤊ was the equivalent of a Roman <M>, such as when Passeri, writing in 1767, transcribed ⤊ELYR : ⤊LMYR, cauślini : aules (CIE 970/ET2 Cl 1.1029), as “CAIMLINI · AVLEM”. This could support option (2). However, the same mistake could have been done in antiquity after the local community had started speaking Latin. Misreading cauśine for caunei could have been done by someone who could read the Etruscan script because of the form of the carved letters. A comparison of the painted version from squeeze 1393 and the carved version from squeeze 1396 are given in Figure 8. In the carving, the san is squashed, with the point closer to the <i> being considerably lower than usual. It is thus possible to interpret the san as part of an <n>, with the <i> making up the final vertical stroke. The <n> is in turn misinterpreted as a partial <e>. ![Figure 8: Line-drawings of the second word on line 2, representing the painted caunei from squeeze 1393 and the carved cauśine from squeeze 1396. By the author.](image) 49 Passeri 1767, 98. As the third bar of the <e> is very close to the anchor ring, it would be easy to interpret the vertical stroke of the <e> as an <i>. Finally, as mentioned under option (3), the tile may have been painted both in antiquity and after being taken from its original context. The pigment present on the squeezes could thus be a combination of ancient and early modern/modern paint. In my opinion, the reading of the carved inscription should be: \[ \text{larθi : caustine} \\ \text{la(r)θi caustine} \] The word-divider in line 1 is a dicolon, as given in CIE, rather than a single punct, as in ET. While the top-most punct is not included in the line-drawing in CIE and is clearly shallow, it is visible (both on the photograph of the tile, Figure 1, and Danielsson’s squeezes, particularly Figure 6). As mentioned above, I judge it most likely that the inscription is in reference to one person, but this does not necessitate rejecting the second line as superfluous, as Rix and Meiser do. While the vast majority of the 893 funerary tiles from Clusium listed in ET2 commemorate only one person, there exist 18 other examples which bear more than one name, 11 of which repeat the name of one person.50 That being said, inscriptions where the carving and pigment give different texts present a challenge to editors, and it is worth asking why the carved letters are taken as more primary. It is clear that inscriptions were painted in antiquity, and paint may have been used as a way to correct mistakes in the carving. However, paint was also added to inscriptions in early modern or modern times. The same day as Danielsson made squeezes of CIE 1973/ET2 Cl 1.1478, he autopsied another tile, CIE 1922/ET2 Cl 1.1411, which is described in the CIE as having been nelegentissimo et stultissimo modo et colore et scalpro restauratus “restored in a most neglectful and foolish way using both paint and chisel”.51 Here too the carved text and the painted text differ. In most cases, ancient objects are not preserved as time-capsules, but have an afterlife, where they have been handled and potentially manipulated by both devious and --- 50 These funerary tiles are CIE 1487/ET² Cl 1.835, CIE 4787/ET² 1.954, CIE 739/ET² 1.1336, CIE 2108/ET² 1.1604, CIE 2200/ET² 1.1711, CIE 2219/ET² 1.1722, CIE 2504/ET² 1.2045, CIE 2729/ET² 1.2215, CIE 2381/ET² 1.2352, CIE 2965/ET² 1.2552, ET² 1.2861. Of these, three write the name in both Latin and Etruscan script. The remaining eight repeat the name, sometimes with minor orthographic variations, e.g. vipinei and vipini (CIE 4787/Cl 1.954). Another seven inscriptions bearing two names commemorate two persons, likely family members. CIE 2785/ET² Cl 1.1130 and CIE 2088/ET² Cl 1.2676 explicitly state that the deceased are husband and wife. 51 Three squeezes of this tile were done (Uppsala University Library, O.A. Danielsson 37:3:2/1922/1412, 37:3:2/1922/1413 and 37:3:2/1922/1414), and show a similar pattern to the squeezes of the case-study, with the paint wearing off more with each squeeze. well-meaning actors. Without conducting laboratory tests on the paint, we cannot say with certainty what the age of the paint is. 3 Conclusion The four squeezes discussed in this article are by no means the only examples of squeezes with paint pigments in Danielsson's squeeze collection. In the first nine boxes, there are 162 examples of squeezes bearing paint pigment. Of these, 148 squeezes are of Etruscan inscriptions, 13 are of early Latin inscriptions from Etruria, and one is of a Latin-Etruscan bilingual inscription (CIE 1729/ET2 Cl 1.1221). Despite Danielsson's frustration at himself for not washing away the red paint on the tile, he did not adopt this as part of his regular preparations, as there are squeezes with paint transfer made by him as late as July 1890. More examples of pigment transfer are bound to be found in the collection as itemization continues, and it is very likely that other squeeze collections focusing on Classical epigraphy contain squeezes with pigments. This makes squeezes a valuable resource in the study of ancient pigment and its use in epigraphy. Acknowledgements: The project to itemize O.A. Danielsson's squeeze collection and prepare it for digitization has received funding in the form of the Bernadotte scholarship from the Royal Academy of Letters, History and Antiquities, the Ellen Fries scholarship from Uppsala University, and funding from the Iris Jonzén-Sandblom and Greta Jonzén Foundation and the Helge Ax:son Johnson Foundation. The author is grateful to James Clackson, Thomas Kiely, Hendrik Mäkeler, Daniel Unruh and Fabrizio Vallelonga. All conclusions and mistakes are my own. Research funding: This work is financially supported by the Uppsala Universitet (91415-7000), Helge Ax:son Johnsons Stiftelse (F22-0164), Iris Jonzén-Sandblom och Greta Jonzénstiftelse (IR2022-0468, IR2021-0614), Kungl. Vitterhets Historie och Antikvitets Akademien (BE2021-0020). References --- Bolman, E. S. 2006. “Late Antique Aesthetics, Chromophobia, and the Red Monastery, Sohag, Egypt.” McDonald, K. 2017. *A Cathedral Field Trip*. The Humanities Blog, University of Exeter. Also available at https://blogs.exeter.ac.uk/humanities/2017/05/10/a-cathedral-field-trip/.
Gravitational synchrotron radiation from cosmic strings Alan Cresswell Robert L. Zimmerman Follow this and additional works at: https://pdxscholar.library.pdx.edu/phy_fac Part of the Physics Commons Let us know how access to this document benefits you. Citation Details Gravitational synchrotron radiation from cosmic strings Alan Cresswell Physics Department, Portland State University, Portland, Oregon 97201 Robert L. Zimmerman Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403 (Received 6 June 1990) This work studies the gravitational synchrotron radiation emitted from arbitrary cusps of cosmic strings. The results are expressed in terms of four parameters describing the motion of such a cusp. The power spectrum is derived for cusps moving at unit velocity. By using a phenomenological approach we also derive the power emitted when the radiation reaction on the cusps is taken into account. In both cases, the synchrotron nature of the radiation produces a power spectrum emitted in a narrow forward cone. If cosmic strings do exist, the radiation emitted by their cusps would seem to be a potential candidate for gravitational-wave detectors. I. INTRODUCTION Most grand unified theories predict the formation of cosmic strings during phase transitions in the early universe. These cosmic strings are one-dimensional objects of the false vacuum of the more symmetric grand unified phase, in an otherwise homogeneous spacetime. Networks of strings intercommute, thus forming a distribution of loops of all sizes. These oscillating loops will lose their energy predominantly by gravitational radiation. A large class of string loops develop cusps during their cycle. The purpose of our work is to compute the beamed gravitational synchrotron radiation emitted by arbitrary cusps. The strongest argument thus far in support of cosmic strings was that loops of string could provide a seed for galaxy formation and explain the observed galaxy correlation function. Recent numerical work, however, questions the plausibility of this scenario but does not rule out the importance of cosmic strings in galaxy formation. Whether or not cosmic strings prove to be the trigger for galaxy formation, their existence has great cosmological importance. The present work shows that cosmic strings could as well be reasonable candidates for gravitational-radiation detection. Several authors have calculated the average gravitational radiation emitted by oscillating loops featuring cusps. (Similar calculations also have been performed for loops with kinks; we are not concerned with those here.) These calculations considered only a few simple classes of periodic string solutions. Such solutions are characterized by a single time scale that is of the order of the size of the loop. Therefore, the average radiation frequency is proportional to the oscillation frequency and thus lies, in general, outside the range of gravitational-wave detectors. On the other hand, more generic loops may have many time scales in which case the frequency of occurrence of the cusps need not be related to the frequency of oscillation of the loop. In fact most of the high-frequency power emitted by a loop will be radiated by the cusps. Moreover the synchrotron nature of this radiation will beam the power in a narrow forward cone. These considerations make arbitrary cusps good candidates for observation by gravitational-wave detectors. In Sec. II, we calculate the spectral distribution of the synchrotron gravitational radiation coming from the most general cusp. As in the electromagnetic case, the result can be expressed in terms of parameters describing the instantaneous circular motion. In Sec. III we use the general expressions obtained in Sec. II to study the case of a cusp moving at the speed of light. In that section we also study the influence of radiation reaction on the result by phenomenologically constraining the cusp to move at a finite Lorentz factor. In both cases we derive the total power emitted per unit solid angle and compute the cutoff frequencies and the half-width of the beam. II. SPECTRAL ENERGY RADIATED BY A CUSP In this section we develop a formalism that allows us to compute the energy radiated by an arbitrary cusp. This formalism parallels the procedure followed in electromagnetism for the treatment of synchrotron radiation emitted by accelerated charges. We obtain the spectrum of radiation in terms of a few arbitrary parameters characterizing the observer’s position and the motion of the cusp. Letting \( x^\mu = x^\mu (\sigma, \tau) \) represent the string’s configuration where \( \sigma \) and \( \tau \) parameters on the string, the string’s dynamics are derived from the constraints \[ \eta_{\mu\nu} \dot{x}^\mu \dot{x}^{\nu'} = 0, \quad \eta_{\mu\nu} (\dot{x}^\mu \dot{x}^\nu + \dot{x}^{\mu'} \dot{x}^{\nu'}) = 0, \tag{1} \] and the wave equations \[ \ddot{x}^\mu - x'^{\mu} = 0, \tag{2} \] which are obtained from varying the string’s action functional which was first proposed by Nambu in the context of hadronic physics. In Eqs. (1) and (2), \( \eta_{\mu\nu} \) represents the space-time metric \((-1,1,1,1)\). The dot and the prime indicate derivatives with respect to the timelike and spacelike parameters \( \tau \) and \( \sigma \) of the string's world sheet. The parameter \( \tau \) can be chosen as the time coordinate \( x^0 \), in which case Eqs. (1) and (2) take the form \[ \dot{x} \cdot x^* = 0, \quad x^2 + x^* = 1, \] where boldface indicates the space part of the string's position four-vector. A general solution to Eq. (3) is written as \[ \dot{x}(\sigma, t) = \frac{1}{2} [a(\xi) + b(\eta)] , \] where we have defined the null parameters \[ \xi = \sigma - t \quad \text{and} \quad \eta = \sigma + t . \] The conditions (3) thus read \[ a'^2 = b'^2 = 1 , \] where the prime now indicates a derivative with respect to the argument of the function. Thus the three-vectors \( a' \) and \( b' \) can be thought of as describing trajectories on a unit sphere, the so-called Kibble-Turok sphere. Whenever the two trajectories intersect, a cusp, moving at unit velocity, develops at that instant. Equations (6) do not include the effect of the gravitational-radiation reaction back on the string. This effect could be significant at the location of the cusp but is very difficult to compute. For our purpose here, we introduce radiation damping phenomenologically by constraining the cusp to move at a finite Lorentz factor. Taking \( v \) (where \( v < 1 \)) to be the speed of the cusp, we thus impose on the cusp the constraints \[ a'^2 = b'^2 = v^2 , \] which are to replace Eq. (6). Since our attention is focused on the cusp, this constraint is only needed in the neighborhood of the cusp and thus does not impose any unphysical requirement to the whole extent of the loop. Equations (7) reduce the size of the Kibble-Turok sphere around the cusp and result in a smoothing of the cusp. We assume that the cusp develops at the origin of coordinates and moves with a positive velocity \( v \) along the \( z \) axis. Thus \[ a(0) = b(0) = 0 , \] \[ a'(0) = -b'(0) = -ve_z . \] The most general solutions \( a' \) and \( b' \) to Eqs. (7), can be written as \[ a'(\xi) = -v \begin{bmatrix} \cos f_a(\xi) & \sin f_a(\xi) \\ \sin f_a(\xi) & \cos f_a(\xi) \end{bmatrix} \] \[ b'(\eta) = v \begin{bmatrix} \cos f_b(\eta) & \sin f_b(\eta) \\ \sin f_b(\eta) & \cos f_b(\eta) \end{bmatrix} \] where \( f_a, g_a, f_b, \) and \( g_b \) are smooth but otherwise arbitrary functions (See Fig. 1). The functions \( a \) and \( b \) can be expanded around the cusp \( (\xi = \eta = 0) \). We have \[ a(\xi) = -\xi v e_z + \frac{1}{2} \xi^2 a''(0) + \frac{1}{6} \xi^3 a'''(0) + \cdots , \] \[ b(\eta) = \eta v e_z + \frac{1}{2} \eta^2 b''(0) + \cdots , \] where the derivatives of \( a \) and \( b \), evaluated at the cusp, are given by the equations \[ a''(0) = -v \begin{bmatrix} \cos f_a \\ \sin f_a \\ 0 \end{bmatrix} , \] \[ b''(0) = v \begin{bmatrix} g_b' \sin f_b + 2\omega_a f'_b \cos f_b \\ -\omega_a' \end{bmatrix} \] and \[ a'''(0) = -v \begin{bmatrix} \cos f_a \\ \sin f_a \\ 0 \end{bmatrix} , \] \[ b'''(0) = v \begin{bmatrix} g_b'' \sin f_b + 2\omega_a f''_b \cos f_b \\ -\omega_b'' \end{bmatrix} . \] We have defined the constants \[ \Omega_a = g_a'' \cos f_a - 2\omega_a f'_a \sin f_a, \quad \omega_a = g_a'(0), \quad g_a'' = g_a''(0) \equiv 0 , \] \[ \Omega_b = g_b'' \cos f_b - 2\omega_b f'_b \sin f_b, \quad \omega_b = g_b'(0), \quad g_b'' = g_b''(0) \equiv 0 , \] (13) As in the electromagnetic case, the emitted gravitational synchrotron radiation will be determined completely by the parameters describing the instantaneous circular motion of the emitter, namely, the radius of curvature, the velocity of that motion and the position of the observer with respect to that motion. For arbitrary cusps, the radius of curvature of the motion will be given by the square of the velocity divided by the acceleration at \( t = 0 \): namely, \[ R = 2v^2 / |a''(0) + b''(0)| . \] Written in terms of the angular frequencies of \( a \) and \( b \), given by \( \omega_a \) and \( \omega_b \) in Eq. (13), the expression for the radius of curvature takes the form \[ R = \frac{2v}{[\omega_a^2 + \omega_b^2 - 2\omega_a \omega_b \cos (f_a - f_b)]^{1/2}} , \] where \( f_a - f_b \) is the angle between the planes tangent to the motions of \( a \) and \( b \), respectively (See Fig. 1). We notice that when \( \omega_a = \omega_b \) and \( f_a = f_b \), the motion of the cusp is linear along the \( z \) axis. The power per solid angle, emitted by the cusp in the direction \( \mathbf{N} = (\sin \theta \cos \phi, \sin \theta \sin \phi, \cos \theta) \) of an observer, is given in the local inertial frame by \[ \frac{dP}{d\Omega} = r^2 N^I(t^I) , \] where \( \langle t^{\mu \nu} \rangle \) is the average, over several wavelengths, of the stress-energy tensor of the gravitational waves. We choose a common form \(^10\) of \( t_{\mu \nu} \) given by \[ t_{\mu \nu} = \frac{1}{8\pi G} (R_{\mu \nu}^{(2)} - \frac{1}{2} \eta_{\mu \nu} \eta^{\rho \sigma} R_{\rho \sigma}^{(2)}) , \] where \( R_{\mu \nu}^{(2)} \) is the second-order part of the Ricci tensor. Following a development that parallels Ref. 9 one obtains the energy radiated over all times in a solid angle \( d\Omega \) by performing a time integration of Eq. (16). The result is \[ \frac{dE}{d\Omega} = \frac{G}{2\pi^2} \int_0^{+\infty} \omega^2 d\omega [T^{\mu \nu}(\omega, k)T_{\mu \nu}(\omega, k)] \] \[ -\frac{1}{2} T^2(\omega, k) , \] where \[ k = \omega N . \] Clearly, the result is valid only because gravity is weak everywhere. The Fourier transform of the stress-energy tensor of the string is given by \[ T_{\mu \nu}(k) = \int d^4x T_{\mu \nu}(x)e^{-ikx} . \] For a string loop of length \( L \) and mass per unit length \( M \) the stress energy is given by \[ T^{\mu \nu}(t, x) = \mu \int_0^L d\sigma \delta^{(3)}(x - f) \frac{\partial}{\partial x} \frac{\partial}{\partial x} - f''x^{\nu} , \] where \( f'' = x''(\sigma, t) \) represents the string configuration. Performing the change to the null string parameters of Eq. (5) and then computing the Fourier transform of Eq. (21) we obtain \[ T^{\mu \nu}(k) = \frac{\mu}{2} \int_{-\infty}^{+\infty} d\xi e^{-ia(\xi + N_a)/2} \] \[ \times \int_{-\infty}^{+\infty} d\eta e^{ia(\eta - N_b)/2} f^{\mu \nu}(\xi, \eta) , \] where \( F^{\mu \nu} \) is given by \[ F^{00} = 1 , \quad | F^{01} \rangle F = -\frac{1}{2} [a'xb' + b'xa'] , \quad | F^{1j} \rangle F = -\frac{1}{2} [a'xb' + b'xa'] . \] Since our purpose is to focus on the radiation emitted at the cusp we expand the arguments of the exponentials around the origin to obtain \[ T^{\mu \nu}(k) = \frac{\mu}{2} \int_{-\infty}^{+\infty} d\xi e^{(a_1\xi + a_2\xi^2 + a_3\xi^3)} \] \[ \times \int_{-\infty}^{+\infty} d\eta e^{(b_1\eta + b_2\eta^2 + b_3\eta^3)} F^{\mu \nu}_{lin} , \] where the coefficients \( a_i \) and \( b_i \) are given in the Appendix. Terms of fourth and higher orders have been neglected in the exponentials. \( F_{lin} \) is the first-order expansion of \( F \) around the origin and is given by \[ F_{lin}^{00} = 1 , \quad F_{lin}^{ij} = \begin{pmatrix} 0 & \cos f_a & \cos f_b \\ 0 & \sin f_a & \sin f_b \\ 0 & 0 & 0 \end{pmatrix} , \] \[ F_{lin}^{xx} = \begin{pmatrix} v^2 & \omega_0 \omega_b \cos f_a & \omega_0 \cos f_b \\ \omega_0 \omega_b \cos f_a & \cos f_b & \cos f_b \\ \omega_0 \cos f_b & \cos f_b & \cos f_b \end{pmatrix} , \] \[ F_{lin}^{xy} = \begin{pmatrix} v^2 & \omega_0 \omega_b \sin f_a & \omega_0 \sin f_b \\ \omega_0 \omega_b \sin f_a & \sin f_b & \sin f_b \\ \omega_0 \sin f_b & \sin f_b & \sin f_b \end{pmatrix} , \] \[ F_{lin}^{zz} = \begin{pmatrix} v^2 & \omega_0 \sin f_a & \omega_0 \sin f_a \\ \omega_0 \sin f_a & \cos f_a & \cos f_a \\ \omega_0 \sin f_a & \cos f_a & \cos f_a \end{pmatrix} . \] In order to express Eqs. (24) in terms of modified Bessel functions we perform the following change of integration variables: \[ \xi' = \xi + b_2/3b_3 , \quad \eta' = \eta + a_2/3a_3 . \] This change of variables is consistent with the \( \xi \) and \( \eta \) expansions appearing in (24) if the new variables defined in (26) remain small. This condition is verified in the case we shall consider, namely, the forward direction, where \( N \) lies in a narrow cone along the \( z \) axis thus having \( \theta \sim 0 \). The majority of the radiation, as in the analog electromagnetic case, is emitted in that direction. After we perform the integration of Eq. (21) we obtain \[ T^{00} = -\frac{1}{2} m \epsilon^{i\Phi} I_d I_b , \quad T^{0r} = v T^{00} , \quad T^{rz} = v^2 T^{00} , \] \[ T^{xx} = \frac{1}{2} m \epsilon^{i\Phi} v^2 \omega_0 \omega_b \cos f_a \cos f_b H_a H_b , \] \[ T^{xy} = \frac{1}{2} m \epsilon^{i\Phi} v^2 \omega_0 \omega_b \sin f_a \sin f_b H_a H_b , \] \[ T^{yy} = \frac{1}{2} m \epsilon^{i\Phi} v^2 \omega_0 \omega_b \sin f_a \sin f_b H_a H_b , \] \[ T^{0s} = \frac{1}{2} m \epsilon^{i\Phi} (\omega_0 \cos f_a I_a H_b + \omega_0 \cos f_a I_b H_a) , \] \[ T^{0y} = \frac{1}{2} m \epsilon^{i\Phi} (\omega_0 \sin f_a I_a H_b + \omega_0 \sin f_a I_b H_a) . \] \( \Phi \) is a phase factor and we have defined the following integrals \[ I_a = \int dx \ e^{i(A_1 x + A_2 x^3)} , \] \[ H_a = \int dx \ e^{i(A_1 x + A_2 x^3)} , \] \[ I_b = \int dx \ e^{i(B_1 x + B_2 x^3)} , \] \[ H_b = \int dx \ e^{i(B_1 x + B_2 x^3)} , \] where \[ A_1 = -\frac{1}{3} \omega (1 - \nu \cos \theta) - \frac{1}{2} \omega \Omega \sin \theta - \frac{3}{4} \omega \Omega \cos \theta \] \[ B_1 = \frac{1}{3} \omega (1 - \nu \cos \theta) + \frac{1}{2} \omega \Omega \sin \theta - \frac{3}{4} \omega \Omega \cos \theta \] \[ A_2 = \frac{\omega \Omega}{12} (\Omega \sin \theta - \omega \Omega \cos \theta) \] \[ B_2 = -\frac{\omega \Omega}{12} (\Omega \sin \theta - \omega \Omega \cos \theta) . \] The \( \omega \)'s and \( \Omega \)'s are defined in Eq. (13). \( \phi_a = f_a \phi \) and \( \phi_b = f_b \phi \) are the angles that the observer makes with, respectively, the planes of motion of \( a \) and \( b \) (see Fig. 1). The integrals in Eqs. (28) are expressed in terms of modified Bessel functions: \[ I_a = \frac{2}{3} \left[ A_1 \right]^{1/2}_{a/2} K_{1/3}(\xi_a) , \] \[ H_a = \frac{2i A_1}{3\sqrt{3} A_2} K_{2/3}(\xi_a) , \] \[ I_b = \frac{2}{3} \left[ B_1 \right]^{1/2}_{b/2} K_{1/3}(\xi_b) , \] \[ H_b = \frac{2i B_1}{3\sqrt{3} B_2} K_{2/3}(\xi_b) , \] where \[ \xi_a = \frac{2A_1^{3/2}}{3\sqrt{3} A_2^{1/2}} , \quad \xi_b = \frac{2B_1^{3/2}}{3\sqrt{3} B_2^{1/2}} . \] The spectral energy radiated is given by the integrand of Eq. (18); namely, \[ \frac{d^2E}{d\omega d\Omega} = \frac{G\omega^2}{2\pi^2} \left[ T^{\mu\nu}(\omega, k) T_{\mu\nu}(\omega, k) - \frac{1}{2} T^2(\omega, k) \right] . \] At high frequency, the dominant contribution to (32) comes from the product of \( H \) integrals that represent \( K_{2/3} \) functions. Thus, when neglecting the \( I \) integrals contributions to Eq. (32), the expression for the spectral energy takes the simple form \[ \frac{d^2E}{d\omega d\Omega} = \frac{G\omega^2 \mu^2}{16\pi^2} v^4 \omega_a^2 \omega_b^2 H_a H_b . \] After writing out the expressions for \( H \) in Eq. (33), we obtain \[ \frac{d^2E}{d\omega d\Omega} = \frac{G\omega^2 \mu^2}{729\pi^2} v^4 \omega_a^2 \omega_b^2 \left[ \frac{A_1 B_1}{A_2 B_2} \right]^2 \] \[ \times K_{2/3}(\xi_a) K_{2/3}(\xi_b) , \] where the coefficients \( A_1, A_2, B_1, \) and \( B_2 \) are given in (29). Expression (34) represents the spectral energy radiated by a cusp moving at velocity \( v \leq 1 \). The answer depends on cusp parameters but not on the overall string configuration. Thus it allows us to study gravitational radiation from the most general cusp of string. These results are reminiscent of the electromagnetic case. Since we are interested in the forward radiation, we can expand the coefficients of Eqs. (29) for small \( \theta \). After setting \( v = 1 \) whenever possible, we obtain \[ A_1 = -\frac{\omega}{4} \left[ 1 + \theta^2 \sin^2 \phi_a + \alpha \cos^2 \phi_a \theta^3 + O(\theta^4) \right] , \] \[ B_1 = \frac{\omega}{4} \left[ 1 + \theta^2 \sin^2 \phi_b - \beta \cos^2 \phi_b \theta^3 + O(\theta^4) \right] , \] \[ A_2 = -\frac{\omega \Omega}{12} \left[ 1 - \alpha \theta - \frac{1}{2} \theta^2 + O(\theta^3) \right] , \] \[ B_2 = \frac{\omega \Omega}{12} \left[ 1 - \beta \theta - \frac{1}{2} \theta^2 + O(\theta^3) \right] , \] where \[ \alpha = \frac{\Omega_a}{\omega_a^2} \] and \( \beta = \frac{\Omega_b}{\omega_b^2} . \] Thus Eq. (34) becomes \[ \frac{d^2E}{d\omega d\Omega} = \frac{16G\mu^2}{9\pi^2} \frac{\omega^2}{\omega_a^2 \omega_b^2} \frac{g(\theta, \nu) K_{2/3}(\xi_a) K_{2/3}(\xi_b)}{8(\theta, \nu) K_{2/3}(\xi_a) K_{2/3}(\xi_b)} , \] where \[ g(\theta, \nu) = \{ (1 - \nu)^2 [(1 - \nu)^2 + O(\theta^3)] \} \[ + \frac{1}{16} \theta^8 \sin^4 \phi_a \sin^4 \phi_b [1 + O(\theta^3)] \] and \[ \xi_a = \frac{\omega}{\omega_a} , \quad \xi_b = \frac{\omega}{\omega_b} \] with \[ \omega_{ca} = 6\omega_a \left[ \frac{1 + \alpha \theta}{\gamma^2} + \theta^2 \right] \left[ \sin^2 \phi_a + \frac{1}{\gamma^2} \left( \frac{2\alpha^2}{9} + \frac{1}{6} \right) \right]^{-1/2} + O(\theta^1) \] \] \[ \omega_{cb} = 6\omega_b \left[ \frac{1 + \beta \theta}{\gamma^2} + \theta^2 \right] \left[ \sin^2 \phi_b + \frac{1}{\gamma^2} \left( \frac{2\beta^2}{9} + \frac{1}{6} \right) \right]^{-1/2} + O(\theta^1) \] \] In Eq. (37), \( g(v, \theta) \) has been written in order to study the cases \( v = 1 \) and \( v \neq 1 \) separately. \( \gamma \) represents the usual Lorentz factor \((1 - v^2)^{-1/2}\) and we assumed \( v = 1 \) wherever possible. Since the modified Bessel functions drop exponentially when their argument becomes greater than one, \( \omega_{ca} \) and \( \omega_{cb} \) represent cutoff frequencies for the radiation. When the observer lies in the plane of motion of \( a \) or \( b \) then \( \phi_a \) or \( \phi_b \) vanish and the cutoff frequencies take a different form; namely, \[ \omega_{ca} = \frac{6\omega_a}{\gamma^3[1 + O(\theta)] - \alpha^2/2\theta^2/2[1 + O(\theta)]} \quad \text{and} \quad \omega_{cb} = \frac{6\omega_b}{\gamma^3[1 + O(\theta)] - \beta^2/2\theta^2/2[1 + O(\theta)]} \quad \text{(40)} \] **III. DISCUSSION** In this section we study the preceding results in the case where the radiation reaction effect on the string can be neglected \((v = 1)\) as well as the more realistic case where this effect is taken into account. We find that in all cases a strong beaming of the radiation in the forward direction can be expected. **A. Case \( v = 1 \)** Neglecting radiation reaction we find that Eq. (37) becomes \[ g(\theta, 1) = \frac{1}{16} \theta^3 \sin^4 \phi_a \sin^4 \phi_b [1 + O(\theta)] \quad \text{(41)} \] The cutoff frequencies [Eqs. (39)] take the form \[ \omega_{ca} = \frac{6\omega_a}{\theta^3 \sin^3 \phi_a} \quad \text{and} \quad \omega_{cb} = \frac{6\omega_b}{\theta^3 \sin^3 \phi_b} \quad \text{(42)} \] In the limit of vanishing \( \theta \) (i.e., when the observer is in line with the motion of the cusp), the cutoff frequencies are infinite and thus all frequencies participate to the spectrum of radiation. For cusps having \( \phi_a \) or \( \phi_b \) vanishing, the corresponding cutoff frequencies are derived from Eqs. (40). We can write an approximate expression for the spectral energy radiated by using the asymptotic expressions for the modified Bessel functions in (36). The asymptotic form of \( K_{2/3}(\xi) \) for \( \xi \ll 1 \) is given by \[ K_{2/3}(\xi) \sim \Gamma(\frac{1}{3})/(2^{1/3}\xi^{2/3}) \quad \text{(43)} \] The energy then takes the form \[ \frac{d^2E}{d\omega d\Omega} = \frac{G'}{(\omega_a \omega_b)^{2/3}} \frac{1}{\omega^{3/3}} \left[ 1 + O(\theta) \right] \quad \text{(44)} \] Next obtain the power in the beam by multiplying the above expression by \( \nu/R \) where we can assume that \( \nu = 1 \); \( R \) is given by Eq. (15). The total power radiated, per solid angle, up to the cutoff frequency \( \omega_c \) is derived by integrating the resulting expression. The result is \[ \frac{dP}{d\Omega} = G' \frac{3\mu^2}{R(\omega_a \omega_b)^{2/3}} \omega_c^{1/3} [1 + O(\theta)] \quad \text{(45)} \] Thus in the limiting case of cusps moving at unit velocities the power radiated per unit solid angle becomes arbitrarily large as \( \theta \) goes to zero since the cutoff frequencies [Eqs. (42)] in the forward direction are infinite. However this singularity is integrable since \( \omega_c^{1/3} \propto \theta^{-1} \) and thus the total power is finite. We can estimate the angular half-width of the beam at a given frequency by setting the arguments of the modified Bessel functions equal to unity. Namely, imposing \( \xi_a = 1 \) and \( \xi_b = 1 \) in Eqs. (38) and (42), we obtain \[ \theta_c = \inf \left[ \frac{6\omega_a}{\omega}^{1/3} \frac{1}{\sin \phi_a} ; \frac{6\omega_b}{\omega}^{1/3} \frac{1}{\sin \phi_b} \right] \quad \text{(46)} \] and thus we find that the beaming increases with frequency as expected. In Eq. (45) it is assumed that \( \sin \phi_a \) and \( \sin \phi_b \) remain strictly positive. If either vanish, Eq. (40) is used instead in order to compute the half width of the beam and we obtain qualitatively the same result. In the case of the simple periodic loops considered by Vachaspati and Vilenkin, 2 for instance, the cusp frequencies are given by \( \omega_a = \omega_0 \) and \( \omega_b = \omega_0 \) where \( \omega_0 \) is the fundamental frequency of the loop, namely \( \omega_0 = 4\pi / L \). For such loops, we recover their result and obtain for the total power radiated in the \( n \)th Fourier harmonic directly from Eq. (45): \[ \frac{dP}{d\Omega} = 3G' \mu^2 n_c^{1/3} \quad \text{(47)} \] where \( n_c \) is the critical harmonic above which there is little radiation. **B. \( v < 1 \) case** Assuming that the radiation reaction has a significant effect on the characteristics of the cusp as observed in the forward direction, we find from Eq. (37) that \[ g(\theta, \nu) = (1 - \nu)^3 [1 + O(\theta)] \quad \text{(48)} \] Equation (48) reflects the assumption that the angle \( \theta \) at which the cusp is observed remains small enough in order for the second term in the expression of \( g(\theta, \nu) \), given by (37), to remain small. From the approximate expressions for the Bessel functions in expression (37) and the value of \( g(\theta, \nu) \) given by (48), we express the spectral energy as Notice that the expression for the energy per unit frequency is, to lowest order, independent of the effects of the radiation reaction on the cusp [compare to Eq. (44)]. Thus the expression for the power in the beam given by Eq. (45) remains valid for the $v < 1$ case. However the cutoff frequencies for the energy radiated do depend on the radiation effects. We have \[ \omega_{\text{ca}} = 6 \omega_\gamma \gamma^3, \quad \omega_{\text{cb}} = 6 \omega_b \gamma^3, \] which is obviously bounded at $\theta = 0$ for all cusps, unlike the $v = 1$ case. However since $\gamma$ can be expected to be large although not infinite, the cutoff frequencies will remain very high. Lastly we derive the beam width. We must realize that when $v \approx 1$, we are dealing with two expansions (in $1 - v$ and in $\theta$) whose terms cannot always be compared (e.g., a $\theta^2$ and a $(1 - v) \theta$ term). It is thus important to keep the physics in mind when we neglect terms. Since $\gamma$ can be assumed to be very large although finite, we make the assumption, in Eq. (39), that for most strings the half-width $\theta_c$ of the beam will satisfy the following inequalities: $\alpha / \gamma^2 << \sin^2 \phi_a \theta_c$ and $\beta / \gamma^2 << \sin^2 \phi_b \theta_c$. In that case, defining the half-width to be the angle for which $\xi(\theta_c) = \xi(0) + 1$, we obtain from Eq. (39) \[ \theta_c = \theta_0 \left( \frac{(2 \omega_{\text{ca}} / 3 \omega)^{1/2} \cdots 1}{\gamma \sin \phi_a} \cdots \frac{(2 \omega_{\text{cb}} / \omega)^{1/2} \cdots 1}{\gamma \sin \phi_b} \right), \] we have \[ \phi_a = \phi_a - \phi, \quad \phi_b = \phi_b - \phi. \] Once again we see that for frequencies of the order of the critical frequencies the radiation is very strongly beamed forward if $\phi_a$ and $\phi_b$ are nonvanishing [when $\phi_a$ and/or $\phi_b$ vanish a result similar to Eq. (51) is derived from Eq. (40)]. APPENDIX The expansion coefficients in Eq. (21) are given by \[ a_1 = -\frac{\omega}{2} (1 - v \cos \theta), \] \[ a_2 = \frac{1}{4} \omega \omega_a \sin \theta \cos \phi_a, \] \[ a_3 = \frac{1}{12} \omega [\sin \theta (g_a' \cos \phi_a - 2 \omega_a f_a' \sin \phi_a) - \omega_a^2 \cos \theta], \] \[ b_1 = \frac{\omega}{2} (1 - v \cos \theta), \] \[ b_2 = -\frac{1}{4} \omega \omega_b \sin \theta \cos \phi_b, \] \[ b_3 = -\frac{1}{12} \omega [\sin \theta (g_b' \cos \phi_b - 2 \omega_b f_b' \sin \theta_b) - \omega_b^2 \cos \theta], \] where \( N = (\sin \theta \cos \phi, \sin \theta \sin \phi, \cos \theta) \), \( \phi_a = \phi_a - \phi, \quad \phi_b = \phi_b - \phi \).
United States Department of the Interior National Park Service National Register of Historic Places Registration Form This form is for use in nominating or requesting determinations of eligibility for individual properties or districts. See instructions in Guidelines for Completing National Register Forms (National Register Bulletin 16). Complete each item by marking "x" in the appropriate box or by entering the requested information. If an item does not apply to the property being documented, enter "N/A" for "not applicable." For functions, styles, materials, and areas of significance, enter only the categories and subcategories listed in the instructions. For additional space use continuation sheets (Form 10-900a). Type all entries. 1. Name of Property historic name Weatherford Downtown Historic District other names/site number 2. Location street & number Roughly bounded by Waco, Water, Walnut and Lee Streets city, town Weatherford state Texas code TX county Parker code 367 zip code 76086 3. Classification Ownership of Property □ private □ public-local □ public-State □ public-Federal Category of Property □ building(s) □ district □ site □ structure □ object Number of Resources within Property Contributing Noncontributing buildings sites structures objects Total Name of related multiple property listing: Historic and Architectural Resources of Weatherford, Texas Number of contributing resources previously listed in the National Register 4. State/Federal Agency Certification As the designated authority under the National Historic Preservation Act of 1966, as amended, I hereby certify that this nomination request for determination of eligibility meets the documentation standards for registering properties in the National Register of Historic Places and meets the procedural and professional requirements set forth in 36 CFR Part 60. In my opinion, the property □ meets □ does not meet the National Register criteria. □ See continuation sheet. Signature of certifying official Texas Historical Commission Date State or Federal agency and bureau 5. National Park Service Certification I hereby certify that this property is: □ entered in the National Register. See continuation sheet. □ determined eligible for the National Register. See continuation sheet. □ determined not eligible for the National Register. □ removed from the National Register. □ other, (explain:) Signature of the Keeper Date of Action Signature of commenting or other official Date State or Federal agency and bureau ### 6. Function or Use <table> <thead> <tr> <th>Historic Functions (enter categories from instructions)</th> <th>Current Functions (enter categories from instructions)</th> </tr> </thead> <tbody> <tr> <td><strong>Commerce/Trade:</strong> specialty store; business; financial institution</td> <td><strong>Commerce/Trade:</strong> specialty store; business; financial institution</td> </tr> <tr> <td><strong>Government:</strong> courthouse; city hall; post office</td> <td><strong>Government:</strong> courthouse; city hall; post office</td> </tr> <tr> <td><strong>Religion:</strong> religious structure</td> <td><strong>Religion:</strong> religious structure</td> </tr> </tbody> </table> ### 7. Description <table> <thead> <tr> <th>Architectural Classification (enter categories from instructions)</th> <th>Materials (enter categories from instructions)</th> </tr> </thead> <tbody> <tr> <td><strong>Italianate</strong></td> <td>foundation <strong>brick, stone</strong></td> </tr> <tr> <td><strong>Commercial style</strong></td> <td>walls <strong>brick</strong></td> </tr> </tbody> </table> Describe present and historic physical appearance. See text which begins with Continuation Sheet 7-1. WEATHERFORD DOWNTOWN HISTORIC DISTRICT The Weatherford Downtown Historic District is focused on the Parker County Courthouse Square at the heart of this town 30 miles west of Fort Worth in north central Texas. U.S. Highway 80 passes from east to west directly through the square where the courthouse sits high in the middle of a large traffic roundabout. The courthouse square itself is on a slight rise approximately three blocks south of the river. The Trinity river tributary, paralleled by the Texas & Pacific Railroad tracks, cut from southeast to northwest through town. The district is a vaguely cruciform shape, comprised of the courthouse square and the commercial areas that developed along the major arteries that lead into the square. The area to the north and east of the square is more heavily developed than that to the south and west, due to its proximity to the railroad. A major artery of automobile-era buildings is concentrated along the east-west axis of Highway 80. A group of churches anchors the district at its southern edge. Architecturally the district is dominated by late 19th and early 20th century commercial buildings in limestone and brick. Also represented are significant governmental and institutional buildings representing several revival and modernistic styles. There are roughly 126 buildings in the area; 64 percent are defined as Contributing (Contr. = 81, Non-Contr. = 45). The layout of the Weatherford Courthouse Square is distinctive. Rather than the courthouse occupying one block bounded by four streets, as is most common in Texas, the courthouse sits on a large block from which four major routes radiate, so that the courthouse sits prominently on axis with each. Consequently, eight blocks front onto the square, creating an unusually dramatic and open public space. The Second Empire courthouse (National Register 1971) in the center of the square, serves as the focal point of the city as it has since its construction in 1886. Its location, on a slightly elevated area at the intersection of two major thoroughfares, enhances the impact of the site and the architecture. The courthouse is surrounded by a simple landscape of grass, shrubbery and a few small trees. Several tiers of parking surround the courthouse block. Originally the square was of unpaved dirt with no landscaping, however, in 1921 it was paved and landscaped with backing from the 20th Century Club. In the mid-1960s, because of heavy traffic and congestion, the highway department created a traffic circle around the courthouse, which, despite a few modifications, is essentially what is seen today. The automobile has become a very dominant element of the Weatherford square, evident in the large areas given over to parking and in the high volume of traffic through the area. The architectural character of the square is defined by late 19th century commercial buildings. The majority of these are 2-story stone structures, deep and narrow in plan, with Italianate detailing on the facades. General characteristics of this type are a verticality of design: tall, narrow windows, often with segmental-arch openings and hood molds; ornate pressed-metal cornices that add height to the parapet; and storefronts heightened by transoms and often decorated with cast-iron columns. Good examples of this type are 105 College Avenue, the Cotten-Bratten Furniture Company at 115 College Avenue, the 100 block of Dallas Avenue, the 100 block of York Avenue, and the Hill Building at 100-108 E. Church Street. While there are many intrusions of later building types on the square, the late 19th century Italianate form is still the most visually dominant architectural influence and establishes the character of the district. There are several other Italianate-influenced buildings of this era along North Main Street that tend to be less ornate than those around the square. This contrast reflects the visibility and stature of a location on the square, and the more subdued architectural interpretations taken in later construction as development moved northward toward the railroad. Examples of the latter type are: Carter-Ivy Hardware at 120 N. Main Street (Site No. CBD-9), J.R. Fleming-Vincent Feeds at 317-319 N. Main Street (Site No. CBD-11) and the structure at 300 N. Main Street (Site No. CBD-10). The second predominate building type in the district is the early 20th century commercial structure. These occur on the square but are most common on the secondary streets that were developed slightly later, and particularly on North Main Street between the square and the railroad stations. They are generally 1-story, rectangular in plan, and most commonly built of brick with simple detailing. The overall appearance of these buildings is horizontal though they retain some of the architectural elements of earlier structures, such as transom windows, decorative cast-iron columns, flat awnings, and central entrances. In place of pressed-metal cornices are simpler decorative brickwork parapets, sometimes with terra cotta details. Examples of this style include the row of buildings from 122 to 134 York Avenue, the structures at 166 and 118 North Main Street, and the row of buildings in the 100 block of West College Street on the south side of the square. In the northwestern sector of the district are the heaviest collection of utilitarian buildings that can be loosely classified as industrial-related. While processing plants were generally built on the river outside of the district, this classification within the district includes primarily small warehouse buildings. These are usually 1-story, very simple box forms with flat or slightly pitched roofs, generally with a parapet. They are most commonly built of brick, though there are examples in stone, as at 317-19 North Main. Their distinctive feature is the large sliding or folding freight doors. Other examples are at 308 North Main and at the corner of York and Spring. Since about World War I development has tended to occur east and west along Highway 80. Since the automobile came into general use this has been the dominant transportation artery through Weatherford. The placement of public buildings in particular along this route illustrates its primacy. The Post Office was built in 1914 at 117 Fort Worth Street, just east of the square. It combines a classical portico with Georgian style windows and balustrade in a Classical Revival interpretation that was considered appropriate for significant public buildings at that time. The Weatherford City Hall was sited west of the square at 119 Palo Pinto Street when it was built in 1933. Deserting the earlier popular revival styles, the City Hall is a fine representation of the Moderne style most frequently used in public building projects of the 1930s. The Public Market was built in a visible location on Fort Worth Street two blocks east of the square. Also a Depression-era public works project, the market is a semi-open shed and has a stuccoed facade with a curvilinear, shaped parapet suggestive of Spanish Colonial Revival architecture. The churches in the district are clustered along South Main Street, one block south of the square. Constructed between 1895 and 1923, most of these borrow from Romanesque or Gothic Revival styles. The First Presbyterian Church (206 South Main), the Church of Christ (201 South Main), and the Parker County Museum (112 West Oak, originally a church) all use rough-faced ashlar limestone and square-plan, corner towers that give them a heavy, rooted appearance in the English tradition. However, each mixes stylistic influences in its own eccentric way. St. Stephens Catholic Church (211 South Main), though built of brick, shares the blocky corner tower and gabled form of its neighbor churches. All Saints Episcopal Church (121 South Waco), like St. Stephens, is built of brick and most closely conforms to the English Gothic style. Weatherford's central business district has retained much of its architectural integrity and, to a degree, its cohesiveness. While many of the buildings are in various stages of deterioration, few are past the point of no return. The addition of new storefronts, windows, and inappropriate awnings are common, but in most cases reversible. Several structures on the square have been altered so severely that the integrity of the original structure is completely gone. Despite these intrusions, 64 percent of the structures in the district are classified as Contributing as of 1990. List of Contributing Properties 110-112 Austin 100-108 E. Church 119 E. Church 101 W. Church 103 W. Church 105 W. Church 107 W. Church 109 W. Church 113 W. Church 101-103 College 115-119 College 118 College 120 College 121-123 College Courthouse (Site No. CBD-1) 100-104 Dallas 106 Dallas 108 Dallas 112 Dallas 112 N. Elm 112-120 Fort Worth 117 Fort Worth 124 Fort Worth 210 Fort Worth 213 Fort Worth 100 Houston 102 Houston 106 Houston 110-112 Houston 116 Houston 121 Houston 122 Houston 107 N. Main 109 N. Main 110 N. Main 111 N. Main 114 N. Main 118 N. Main 120 N. Main 124 N. Main 201 N. Main 203 N. Main 205 N. Main 209 N. Main 215 N. Main 220 N. Main 224 N. Main 300-304 N. Main 303 N. Main 306 N. Main 308 N. Main 310 N. Main 313 N. Main 315 N. Main 317 N. Main 319 N. Main 108 S. Main 110 S. Main 116-118 S. Main 200 S. Main 201 S. Main 211 S. Main 301 S. Main 112 W. Oak 113 W. Oak 111 Palo Pinto 119 Palo Pinto 121 S. Waco 111-113 York 120 York 122 York 124 York 126 York 127-133 York 128 York 130 York 203 York 205 York 207 York 208 York 210 York List of Non-Contributing Properties 100-102 Austin 201 York 104-108 Austin 209 York 106 W. Bridge 220 York 110 E. Church 314 York 112 E. Church 318 York 131 W. Church 105 College 107-111 College 208 College 300 College 108 Fort Worth 110 Fort Worth 122 Fort Worth 200 Fort Worth 201 Fort Worth 202 Fort Worth 204 Fort Worth 205-209 Fort Worth 206 Fort Worth 117-119 N. Main 121-123 N. Main 207 N. Main 208 N. Main 213 N. Main 217 N. Main 219 N. Main 223 N. Main 311 N. Main 112 S. Main 114 S. Main 123 S. Main 124 S. Main 203 S. Main 209 S. Main 101-109 Trinity 111 Trinity 123 S. Waco 101-105 York 107 York 134 York 8. Statement of Significance Certifying official has considered the significance of this property in relation to other properties: - [ ] nationally - [ ] statewide - [x] locally Applicable National Register Criteria: - [x] A - [ ] B - [x] C - [ ] D Criteria Considerations (Exceptions): - [x] A - [ ] B - [ ] C - [ ] D - [ ] E - [ ] F - [ ] G Areas of Significance (enter categories from instructions) - Architecture - Commerce - Government - Industry - Religion <table> <thead> <tr> <th>Areas of Significance</th> <th>Period of Significance</th> <th>Significant Dates</th> </tr> </thead> <tbody> <tr> <td>Architecture</td> <td>1874-1945</td> <td>N/A</td> </tr> <tr> <td>Commerce</td> <td></td> <td></td> </tr> <tr> <td>Government</td> <td></td> <td></td> </tr> <tr> <td>Industry</td> <td></td> <td></td> </tr> <tr> <td>Religion</td> <td></td> <td></td> </tr> </tbody> </table> Cultural Affiliation - N/A Significant Person - N/A Architect/Builder - N/A State significance of property, and justify criteria, criteria considerations, and areas and periods of significance noted above. See text which begins with Continuation Sheet 8-1. 9. Major Bibliographical References Parker County Historical Commission, History of Parker County, ed. Helen Lance, Taylor Publishing Co. 1980. Smythe, H., Historical Sketch of Parker County and Weatherford, Texas, St. Louis, Louis C. Lavat, 1877. 10. Geographical Data Acreage of property 31 acres UTM References <table> <thead> <tr> <th>Zone</th> <th>Easting</th> <th>Northing</th> </tr> </thead> <tbody> <tr> <td>A 1.4</td> <td>6</td> <td>1</td> </tr> <tr> <td>B 1.4</td> <td>6</td> <td>1</td> </tr> <tr> <td>C 1.4</td> <td>6</td> <td>1</td> </tr> <tr> <td>D 1.4</td> <td>6</td> <td>1</td> </tr> </tbody> </table> Verbal Boundary Description See text which begins with Continuation Sheet 10-1. Boundary Justification See text which begins with Continuation Sheet 10-1. 11. Form Prepared By Sandy Stone and Jamie Wise (with Tory Laughlin Taylor, Architectural Historian, THC) 4109B West 6th Street Austin, Texas 78703 512/474-8076 Texas The Weatherford Downtown Historic District is a collection of commercial and institutional buildings which together illustrate the town’s development as a commercial and governmental center for its region, and the evolution of architectural types through its late 19th and early 20th century growth. The district is being nominated in association with the historic contexts "Community and Regional Settlement, Weatherford, Texas, 1852-1874" and "Community and Regional Development, Weatherford, Texas 1874-1945." The nomination relates to the statewide contexts of Agriculture and Community and Regional Development in Texas. It meets National Register criterion A for its association with the workings of commerce and government in Weatherford from approximately 1880 to 1945, and it meets criterion C, significant in the area of Architecture and Urban Planning, as an excellent collection of vernacular commercial buildings within a distinctive courthouse square plan. The district is being nominated at the local level of significance. Weatherford follows a historical pattern of development typical of many frontier seats of government in Texas, evolving a diversified economy as a hub of regional commerce. The town initially developed around the courthouse square with small frame and brick structures housing businesses that provided the most essential commodities to regional farmers and ranchers. Weatherford is unusual in the length of time that it remained a frontier community at this stage of development. Through approximately 25 years, including early settlement, Indian raids, the Civil War and Reconstruction, Weatherford remained a sparsely developed outpost community for ranching and agriculture. The arrival of the Texas and Pacific Railroad in 1880 gave Weatherford the means to become a regional commerce and distribution center. The resulting affluence and availability of more sophisticated building materials made possible the construction of the buildings which characterize Weatherford’s business district today. The Second Empire courthouse and the Italianate structures which line the square and North Main Street, were constructed between about 1875 and 1910. Historically, these were linked with banks, mercantiles or service businesses, all of which were indirect products of regional ranching and cash crops. Though there are city blocks which have lost many buildings from this period, enough structures remain to give a sense of the town as it was during its formative period of affluence. The influence that transportation routes have had on the growth patterns of Weatherford cannot be overstated and is still evident from the historic development which survives in the district. The Texas & Pacific Railroad tracks were laid in 1880 along the south side of the Trinity river tributary, passing three blocks north of the square, running southeast to northwest. This triggered early northward growth of the Weatherford’s business district. Any industrial processing or distribution relied on the proximity of both the river and the railroad for power and transportation. The industrial district thus naturally developed in the northeast sector of downtown, proximate to the tracks and the river. As long as the railroad remained the dominant means of transportation, commercial development tended to grow northward as well, strung between the square and the railroad depot near North Main Street. This accounts for the heavy concentration of historic commercial buildings along North Main Street. While Weatherford built its wealth on ranching, in the late 19th century diversified agriculture increasingly dominated the economy of the community. The railroad provided the means for Weatherford to become a regional processing and distribution center for agriculture. Of the six granaries, cotton and oil mills that existed before 1889, only the Weatherford Castor Oil Works and the Bradfish Grain Elevator are known to remain. The abandoned Planters Oil Mill, northwest of town, may be standing, albeit in a deteriorated state. Bradfish dates from 1910, and is the only remaining granary that was built prior to World War II. The industrial area of town continues to have a fabric similar to the earlier periods, due to low density development and the presence of one newer granary. Still evident in the district is the way in which North Main Street developed with small, simple warehouse and retail buildings. Many buildings lining North Main Street today, date from the final two decades of the 19th century and are in good condition. These 1- and 2-story structures were built to the front and side property lines, with the depth at the rear varying. Historically, businesses adjoining the industrial district included wholesale grocers, a Chinese laundry, a soda and wine factory, iron works and wagon yards. The emergence of the automobile as a significant transportation mode is evident in Weatherford's growth patterns early in the 20th century. The Bankhead Highway, constructed just before World War I, was one of the earliest efforts to create a transcontinental highway. It passed through downtown Weatherford on Fort Worth and Palo Pinto streets. This axis, passing through the square, thereby gained greater visual and symbolic significance as the primary entrances to Weatherford. The historical importance of this route is evident in the siting of public buildings along it (as noted in Section 7). In addition, the simple brick commercial buildings of the early to mid-20th century along this route are important remnants of the early automobile era and reflect the stylistic transition from the revival styles to modernism in architecture. These structures, though of a type common throughout the U.S., display integrity of forms and materials, and exemplify a critical era in the community's development. Another notable historical pattern in downtown Weatherford is the clustering of churches south of the square. Though there is evidence that land was allocated for churches with the original platting of the city (see historic context), the surviving clustering of churches appears rather to be the result of a natural segregation of functions within the town. Whereas northeast Weatherford was industrial due to its proximity to the railroad and river, southwest Weatherford had developed in the late 19th century as a residential area, with some of the town’s finest homes set visibly on the hills. Around the turn of the century when the major Weatherford denominations were building new churches to house their congregations, it was natural to look adjacent to the established residential neighborhood, yet close to the square. These churches, built between 1895 and 1923, include some of Weatherford’s best examples of revival style architecture. While Weatherford’s downtown has continued to evolve to a certain extent, the district’s dynamic growth effectively ended with the Depression. Little was built during the 1930s and 1940s, with the exception of several Public Works projects including the Public Market at 213 Fort Worth Street. Deterioration of the central business district began in the 1950s and continued through the 1960s and 1970s. By the 1980s, however, there was a renewed interest in restoration and many of the downtown buildings were renovated. Today, Weatherford has a very active historical society and is a participant of the Main Street Program. Both of these organizations have been instrumental in the restoration of historic structures in the city. Because of its strong and diverse economic base, and position as a "bedroom "community for Fort Worth, Weatherford remains economically stable. This stability has led to renewed community pride and a heightened desire to see the central business district restored and preserved. VERBAL BOUNDARY DESCRIPTION: Beginning at the north property line of 112 Austin Avenue, proceed east along the south curb line of Trinity Avenue to Walnut Street. Then proceed south along the west curb line to the rear property line of 210 Fort Worth Street, following that property line to the west curb line of Elm Street. Then proceed south along the west curb line to East Church Street, and follow the north curb line to the rear property line of 113 College Avenue. Then follow the rear property line south to the south property line of 123 College Avenue. Proceed west along this line to the west curb line of College Avenue. Continue south along the west curb line to the south property line of 301 S. Main Street. Follow this property line to the center line of S. Main Street, and continue north along this line to the south property line of 200 S. Main. Turn west and continue to the east curb line of Houston Street, then proceed north to the south property line of 122 Houston Street, then turn west and follow this line to the east curb line of S. Waco Street. Turn north along this line and follow it to the north curb line of Palo Pinto Street. Proceed east to the rear property line of 101 York Avenue, then turn north and follow the rear property lines to the north property line of 209 York Avenue. Turn east and follow this property line the center line of York Avenue. Continue north to the north property line of 319 N. Main Street. Follow this property line to the center line of N. Main Street. Turn south and proceed to the north property line of 310 N. Main Street. Continue east along this line to the rear property line of 310 N. Main Street, then turn south and follow this line along Austin Avenue to the point of origin. BOUNDARY JUSTIFICATION The district boundaries encompass the historic core of the governmental and commercial district, including the main arteries of historic development, while excluding residential neighborhoods and areas of post-1945 infill development. United States Department of the Interior National Park Service National Register of Historic Places Continuation Sheet Section number _____ Page _____ SUPPLEMENTARY LISTING RECORD NRIS Reference Number: 90001745 Date Listed: 11/23/90 Weatherford Downtown Historic District Parker TX Property Name County State Weatherford MPS Multiple Name --------------------------------------------- This property is listed in the National Register of Historic Places in accordance with the attached nomination documentation subject to the following exceptions, exclusions, or amendments, notwithstanding the National Park Service certification included in the nomination documentation. Signature of the Keeper 1/21/91 Date of Action Amended Items in Nomination: Classification: Under Category of Property, only "district" should be checked. This information was confirmed with Bruce Jensen of the Texas SHPO. DISTRIBUTION: National Register property file Nominating Authority (without nomination attachment) United States Department of the Interior National Park Service National Register of Historic Places Continuation Sheet Section number ______ Page ______ Weatherford MPS Parker County, TEXAS COVER 1. Weatherford Downtown Historic District Date Listed Substantive Review 11/19/90 Substantive Review 11/23/90 UNITED STATES DEPARTMENT OF THE INTERIOR NATIONAL PARK SERVICE NATIONAL REGISTER OF HISTORIC PLACES EVALUATION/RETURN SHEET REQUESTED ACTION: NOMINATION PROPERTY: Weatherford Downtown Historic District NAME: MULTIPLE Weatherford MPS NAME: STATE & COUNTY: TEXAS, Parker DATE RECEIVED: 10/10/90 DATE OF 16TH DAY: 11/08/90 DATE OF WEEKLY LIST: REFERENCE NUMBER: 90001745 NOMINATOR: STATE REASONS FOR REVIEW: APPEAL: N DATA PROBLEM: Y LANDSCAPE: N LESS THAN 50 YEARS: Y OTHER: N PDIL: N PERIOD: Y PROGRAM UNAPPROVED: N REQUEST: N SAMPLE: Y SLR DRAFT: Y NATIONAL: N COMMENT WAIVER: N ACCEPT [ ] RETURN [ ] REJECT [ ] ABSTRACT/SUMMARY COMMENTS: The Weatherford Downtown Historic District is significant for its portrayal of the development of commerce and governmental institutions in Weatherford. In addition, the district encompasses a collection of vernacular commercial buildings arranged around a courthouse square. The cruciform shape of the district includes a significant cluster of churches at the southern end. RECOM./CRITERIA [Accept/Reject] REVIEWER [Autumnett / Lee] DISCIPLINE [History] DATE [11/23/90] DOCUMENTATION see attached comments Y/N see attached SLR Y/N CLASSIFICATION __count __resource type STATE/FEDERAL AGENCY CERTIFICATION FUNCTION __historic __current DESCRIPTION __architectural classification __materials __descriptive text SIGNIFICANCE Period Areas of Significance--Check and justify below Specific dates Builder/Architect Statement of Significance (in one paragraph) __summary paragraph __completeness __clarity __applicable criteria __justification of areas checked __relating significance to the resource __context __relationship of integrity to significance __justification of exception __other BIBLIOGRAPHY GEOGRAPHICAL DATA __acreage __verbal boundary description __UTMs __boundary justification ACCOMPANYING DOCUMENTATION/PRESENTATION __sketch maps __USGS maps __photographs __presentation OTHER COMMENTS Questions concerning this nomination may be directed to ____________________ Phone ____________ Signed ____________________ Date __________ 1. PARKER COUNTY COURTHOUSE, WEATHERFORD CENTRAL BUSINESS DISTRICT, CBD. 2. WEATHERFORD, TEXAS 3. SANDY STONE 4. 1/40 5. TEXAS HISTORICAL COMMISSION 6. NORTH 7. # 1 1. Cotton Bration Building, Weatherford Central Business District (CBD) 2. Weatherford, Texas 3. Sandy Stone 4. 1/40 5. Texas Historical Commission 6. SE 7. #2 1. Cotton-Granton Funeral Home, WFD CBD 2. Weatherford, Texas 3. Sandy Stone 4. 1/90 5. Texas Historical Commission 6. East 7. #3 1. GOLDFATON FUNERAL HOME, WF P O BOX 2. WEATHERFORD, TEXAS 3. SANDY STONE 4. V 90 5. TEXAS HISTORICAL COMMISSION 6. EAST 7. #4 1. 100 COLLEGE AVE, UTD CBD 2. WEATHERFORD, TEXAS 3. SANDY STONE 4. 1/10 5. TEXAS HISTORICAL COMMISSION 6. EAST 7. #5 1. 110, 112 Austin Ave, WFD CBD 2. Weatherford, Texas 3. Sandy, Stone 4. 1/6 5. Texas Historical Commission 6. East 7. #6 1. 100 W. Dallas Ave., WFD CBD 2. Weatherford, TX 3. Sandy Stone 4. 1/4 5. Texas Historical Commission 6. NW 7. #7 1. 112 W. DALLAS AVE. WFD, CRD, CRD3 2. WEATHERFORD, TEXAS 3. SANDY STONE 4. 1/40 5. TEXAS HISTORICAL COMMISSION 6. N/E 7. #8 1. 111 York Ave., WFO CBD 2. Weatherford, TX 3. Sandy Stone 4. 1/90 5. Texas Historical Commission 6. W 7. #9 1. KNIGHTS OF CYTHIAS HALL, 110 HOUSTON ST, WFO CBD, CBD 2. WEATHERFORD, TX 3. SANDY STONE 4. 190 5. TEXAS HISTORICAL COMMISSION 6. W 7. #10 1. 116 Houston, WFO, CBD, CBID 2. Weatherford, Texas 3. Sandy Stone 4. V40 5. Texas Historical Commission 6. SW 7. #11 1. 161 W. CHURCH ST. WFD CBD 9 2K 2. WEATHERFORD, TX. 3. SANDY STONE 4. 9/10 5. TEXAS HISTORICAL COMMISSION 6. 9 7. #13 1. 100 E CHURCH ST, CFD CBD CBD '18 2. WEATHERFORD, TX 3. SANDY STONE 4. 1/90 5. TX. HISTORICAL COMMISSION 6. N W 7. #14 1. Carter Ivy Hardware, 120 N. Main St., Lufkin, TX, 75904 2. Weatherford, Texas 3. Sandy Boone 4. 5/40 5. TX Historical Commission 6. E 7. #15 1. 207 N. MAIN ST., WPD CBD 2. WEATHERFORD, TX 3. JAMIE WISE 4. 1/10 5. TR HISTORICAL COMMISSION 6. W 7. #16 1. 224 N. MAIN ST., WFO CBD 2. WEATHERFORD, TX 3. JAMIE WISE 4. 490 5. TX: HISTORICAL COMMISSION 6. E 7. #17 1. 320 N. MAIN ST, WFO CBD, CBP 10 2. WEATHERFORD, TX 3. JAMIE NICE 4. V192 5. TX HISTORICAL COMMISSION 6. E 7. #18 1. 310 N. MAIN, WFO CBD, CBD 34X 2. WEATHERFORD, TX 3. JAMIE WBE 4. V10 5. TX HISTORICAL COMMISSION 6. E. 7. # 19 1. 317-17 E. MAIN ST. 2. WEATHERFORD, TX. 3. JAMIE WISE 4. V90 5. TX. HISTORICAL COMMISSION 6. W. 7. #20. 1. 120-130 York 2. WFD CBD, CBD. 18K 3. Weatherford, TX. 4. V40 5. Texas Historical Commission 6. E 7. #21 1. 200 York Ave / 201 Nineteenth St, WFD CBD 2. Weatherford, TX 3. Sandy Stone 4. K-10 5. TX Historical Commission 6. E 7. #22 1. OLD CITY HALL, 1111 PALO PINTO ST, UTD CB10, CB1D 14 2. WEATHERFORD, TX 3. SANDY STONE 4. YTO 5. TR HISTORICAL COMMISSION 6. 5 7. #23 1. 112 N. CAL, WFCB DSC DB 18 2. WEATHERFORD, TR 3. SANDY STONE 4. 1/90 5. TR HISTORICAL COMMISSION 6. NW 7. #24 1. 200 S. MAIN ST, WFO OBD 1, OBD 12 2. WEATHERFORD 1TR 3. SANDY STONE 4. VSO 5. TR HISTORICAL COMMISSION 6. N 7. #25 1. ST. STEPHENS CHURCH, 211 S. MAIN ST., CBP: 14 2. WEATHERFORD, TX 3. SANDY STONE 4. 190 5. TX HISTORICAL COMMISSION 6. E. 7. # 26 1. 301 S. MAIN, UFD CBD, CBD 2. WEATHERFORD, TX 3. SANY STONE 4. 1/40 5. TX HISTORICAL COMMISSION 6. E 7 #27 1. PUBLIC MARKET, 213 FT. WORTH ST, CBD. 5 2. WEATHERFORD TX. 3. SANDY STONE 4. Y90 5. TX. HISTORICAL COMMISSION 6. N N 7. # 28 1. TX & PACIFIC RR STATION, 100 BLOCK WATER ST., CBD 17 2. WEATHERFORD, TX 3. JAMIE WISE 4. 1/30 5. TX HISTORICAL COMMISSION 6. SN 7. 2/29 1. WEATHERFORD STATION, 1901 FT, NORTHERN, CBODS 2. WEATHERFORD, TX 3. SANDY STONE 4. 1/40 5. TX HISTORICAL COMMISSION 6. N 7. #30 1. WEATHERFORD STATION/SANTA FE RR 401 PT, NORTH ST, CBD, G 2. WEATHERFORD TR. 3. SANDY STONE 4. 190 5. TR HISTORICAL COMMISSION 6. 41 7. #31 November 20, 1990 James T. Coe, Director Office of Real Estate Facilities Department U.S. Postal Service 475 L'Enfant Plaza, SW Washington, TX 20260-6430 Re: United States Post Office, 117 Fort Worth Weatherford, Parker County, Texas Dear Mr. Coe: We are pleased to inform you that the above-mentioned property has been nominated to the National Register of Historic Places. A legal notice for the Weatherford Downtown Historic District was placed in the classified section of the Weatherford Democrat on June 20, 1990 and the district was approved by the State Board of Review on July 21, 1990 in Dallas, Texas. The National Register is the federal government's official list of historic properties worthy of preservation. Listing in the National Register provides recognition, assists in preserving our nation's heritage and results in the following for historic properties: 1. Consideration in planning for federal, federally licensed, and federally assisted projects. Section 106 of the National Historic Preservation Act of 1966 requires that federal agencies allow the Advisory Council on Historic Preservation to have an opportunity to comment on all projects affecting historic properties listed in the National Register. For further information, please refer to 36 CFR 800. 2. Eligibility for federal tax provisions. If a property is listed in the National Register, certain federal tax provisions may apply. The Tax Reform Act of 1986 revises the historic preservation tax incentives authorized by Congress in the Tax Reform Act of 1976, the Revenue Act of 1978, the Tax Treatment Extension Act of 1980, the Economic Recovery Tax Act of 1981, Tax Reform Act of 1984, and, as of January 1, 1987, provides for a 20 percent investment tax credit with a full adjustment to basis for rehabilitating historic commercial, industrial, and rental residential The State Agency for Historic Preservation buildings. The former 15 percent and 20 percent Investment Tax Credits (ITCs) for rehabilitations of older commercial buildings are combined into a single 10 percent ITC for commercial or industrial buildings built before 1936. The Tax Treatment Extension Act of 1980 provides federal tax deductions for charitable contributions for conservation purposes of partial interests in historically important land areas or structures. Whether these provisions are advantageous to a property owner is dependent upon the particular circumstances of the property and the owner. Because tax aspects as outlined above are complex, individuals should consult legal counsel or the appropriate local Internal Revenue Service office for assistance in determining the tax consequences of the above provisions. For further information on certification requirements, please refer to 36 CFR 67. 3. Consideration in issuing a surface coal mining permit: In accordance with the Surface Mining and Control Act of 1977, there must be consideration of historic values in the decision to issue a surface coal mining permit where coal is located. For further information, please refer to 30 CFR 700 et seq. 4. Qualification for federal grants for historic preservation when funds are available. Presently, funding is unavailable. National Register listing does not: 1. require the owner to provide public access, 2. obligate the owner to maintain the property, 3. require notification of changes in ownership, or 4. impose restrictions of any kind unless grant assistance is received or tax credits are taken. Owners of private properties nominated to the National Register of Historic Places have an opportunity to concur in or object to listing in accordance with the National Historic Preservation Act and 36 CFR 60. Any owner or partial owner of private property who chooses to object to listing may submit to the State Historic Preservation Officer a notarized statement certifying that the party is the sole or partial owner of the private property and objects to the listing. If a majority of the owners object to the listing, the district will not be listed. Each owner or partial owner of private property in a district has one vote regardless of how many properties or what part of the property that party owns. If the district cannot be listed because a majority of owners object prior to the submission of a nomination by the State, the State Historic Preservation Officer shall submit the nomination to the Keeper of the National Register for a determination of eligibility of the district for listing in the National Register. If the district is then determined eligible for listing, although not formally listed, federal agencies will be required to allow the Advisory Council on Historic Preservation an opportunity to comment before the agency may fund, license, or assist a project which will affect the property. If you choose to object to the listing of your property, the notarized objection must be submitted to Mr. Curtis Tunnell, State Historic Preservation Officer, Texas Historical Commission, P.O. Box 12276, Austin, TX, 78711. If you wish to comment on the nomination of the property to the National Register, please send your comments to the State Historic Preservation Officer as soon as possible. The district is currently being reviewed by the Department of the Interior, National Park Service in Washington, D.C. A copy of the nomination and information on the National Register and Federal tax provisions are available from the above address upon request. Sincerely, [Signature] James W. Steely, Deputy State Historic Preservation Officer JWS/mc xc: Postmaster Weatherford, Texas 76086
EXACT SIMULATION OF EXTRINSIC STRESS-RELEASE PROCESSES YOUNG LEE,∗ Harvard University PATRICK J. LAUB,** University of New South Wales THOMAS TAIMRE,*** University of Queensland HONGBIAO ZHAO, **** Shanghai University of Finance and Economics JIANCANG ZHUANG, ***** Institute of Statistical Mathematics Abstract We present a new and straightforward algorithm that simulates exact sample paths for a generalized stress-release process. The computation of the exact law of the joint inter-arrival times is detailed and used to derive this algorithm. Furthermore, the martingale generator of the process is derived, and induces theoretical moments which generalize some results of [3] and are used to demonstrate the validity of our simulation algorithm. Keywords: Stress-release process; inhibitory point process 2020 Mathematics Subject Classification: Primary 60G20 Secondary 60G55; 65C05 1. Introduction Stress-release processes are a class of point processes, the first of which were self-correcting processes [7]. Intuitively, a process is self-correcting if the occurrence of past points inhibits the occurrence of future points. The stress-release processes are a generalization of self-correcting processes and were introduced in a series of papers by Vere-Jones and others [24, 25] as well as extensions to coupled stress-release processes [11, 12, 18] and further developments [1, 2]. In this study we work with a generalization of the stress-release process which includes an exogenous point process term whose values upon arrival are modeled by a positive real-valued random variable. We call our model the extrinsic stress-release processes. We present a new formula for the law of the joint inter-arrival times for extrinsic stress-release processes. As a natural consequence, an exact simulation algorithm is then proposed which gives an alternative method to generating sample paths relative to standard methods [9]. Our exact simulation algorithm naturally extends the results of [22] as a special case. The extension of our model is motivated by the influence of exogenous geophysical data on earthquake occurrence (see e.g. [15] and [26]). Point process models of this kind are typically used to describe the evolution of stochastic phenomena in earthquake modeling, and it is important to be able to simulate them for reliable predictions of damage due to a range of earthquake scenarios. Thinning algorithms [14] have been successfully employed to simulate a wide range of point processes, such as inhomogeneous point processes (see [5, pages 270–271] and [23]), or Hawkes processes [19]. Indeed, the same idea can be applied to the generalized stress-release process proposed here. In this paper, simulation of the extrinsic stress-release process by our exact algorithm will be compared with the standard thinning algorithm. Finally, we present the infinitesimal generator for extrinsic stress-release processes. This generator is intimately linked to the martingale problem, which is used to characterize the weak solutions of partial integro-differential equations [10], and it allows us to derive the theoretical reciprocal moments of the intensity function. In Section 6 these reciprocal moments are used to demonstrate the correctness of our simulation algorithms. Basic notions and results in stochastic calculus are taken as prerequisites throughout the present text (see e.g. [17]). 2. Extrinsic stress-release model At the base of everything is some filtered probability space \((\Omega, \mathcal{F}, \mathbb{F}, \mathbb{P})\). We assume that \(\mathcal{F}_0\) is trivial, and the filtration \(\mathbb{F} := (\mathcal{F}_t)_{t \geq 0}\) fulfills the usual conditions and is generated by a point process \(N(\cdot)\) on \(\mathbb{R}_+\), where \(0 < T_1 < T_2 < \cdots\) denote the occurrence times of the events. Let \(N_t = \sharp\{T_i : 0 < T_i \leq t\}\) be the number of the occurrence points in the time interval \((0, t]\) with \(N_0 = 0\). Furthermore, we let \(N'_t = \sharp\{T'_j : 0 < T'_j \leq t\}\) be a Poisson process on \(\mathbb{R}_+\), with arrival times \(0 < T'_1 < T'_2 < \cdots\) endowed with intensity \(\rho\), which is independent of \(N_t\), with \(N'_0 = 0\). **Definition 2.1.** The proposed extrinsic stress-release process \(N(\cdot)\) is a point process on \(\mathbb{R}_+\) with conditional intensity function given by \[ \lambda_t := \lambda(t \mid \mathcal{F}_t) = \lambda_0 \exp (\beta t - S_t - S'_t), \quad t \geq 0, \] where \(S_t = \sum_{i : T_i < t} X_i\) and \(S'_t = \sum_{j : T'_j < t} Y_j\) are the compound point process and compound Poisson process, respectively. The \(X_i\) and \(Y_j\) are i.i.d. positive random variables, with distribution functions \(F_X\) and \(F_Y\) respectively, and the stress accumulation rate is the constant \(\beta > 0\). Between jumps, \(\lambda_t\) increases exponentially with a positive rate of \(\beta > 0\). Jumps are downward multiplicative factors of size \(e^{-X_i} < 1\) for a self-arrival at time \(T_i\), or of size \(e^{-Y_j} < 1\) for an external arrival at time \(T'_j\). When a self-arrival occurs at time \(T_i\), \(N_t\) increases by one, hence \((N_t, \lambda_t)\) is a Markov process. Instead of separating the self-arrivals of \(N_t\) and the external arrivals of \(N'_t\), it is sometimes convenient to consider all the arrivals indiscriminately. As such, we label the \(k\)th arrival as \(T_k\), and it can correspond either to some self-arrival \(T_i\) or some external arrival \(T'_j\). See Figure 1 for an example realization of the extrinsic stress-release process, with the effects of the self-arrivals and external arrivals on the conditional intensity function \(\lambda_t\) highlighted. **Remark 2.1.** Our proposed extrinsic stress-release process differs slightly from the coupled stress-release model of [11]. Their equivalent of \(X_i\) and \(Y_j\) from Definition 2.1 are not unobserved random variables: they are deterministic functions of the observed earthquake magnitudes. In our proposed model, we allow for these quantities to take any i.i.d. random Exact simulation of extrinsic stress-release processes FIGURE 1. An example realization of an extrinsic stress-release process, with $\lambda_0 = 1$, $\beta = 1.5$, $\rho = 2$, and $X_i \sim \text{Exp}(1)$ and $Y_j \sim \text{Exp}(2)$. Note that $N$ is càdlàg while $\lambda$ is càgàld. variables that are positive and unobserved, so our formulation generalizes theirs. Unlike ours, they allow for model parameters $c$ and $c'$ in the exponent of equation (2.1) of the form $$-cS_t - c'S'_t,$$ where $c$ and $c'$ can take either negative or positive values, thereby allowing for both damping and excitation. We only consider the inhibitory regime, i.e. $c = c' = 1$, so in this case their formulation for general $c$ and $c'$ subsumes ours. In either formulation, little or no work has appeared on exact simulation strategies for the coupled stress-release model. We also add some new aspects to the computation of explicit generators, facilitating moment computations. For other theoretical and stationary moment calculations without the exogenous term $S'_t$, see [3], [16], [20], and [21]. 3. The law of joint inter-arrival times In this section we present the explicit law of the joint inter-arrival times for extrinsic stress-release processes. This terminology, ’joint inter-arrival time’, refers to the time between each of $T^o_k$ arrivals (defined in Section 2). Itô’s formula [8] splits $\lambda_t$ into continuous and jump components: $$\lambda_t = \lambda_0 + \int_0^t \beta \lambda_s ds + \sum_{i: T_i \leq t} \lambda_{T_i} (e^{-X_i} - 1) + \sum_{j: T'_j \leq t} \lambda_{T'_j} (e^{-Y_j} - 1).$$ Between consecutive jumps the $\lambda$ process evolves according its continuous part. In particular, conditioned on $T^o_k$ and $\lambda_{T^o_k}$, we have $$\lambda_t = \lambda_{T^o_k} \exp (\beta(t - T^o_k)) \quad \text{for} \quad t \in (T^o_k, T^o_{k+1}).$$ (3.1) The intensity of the $T^o_k$ arrivals is the combination of the $T^i_l$ and $T^r_j$ arrival intensities $\lambda_l + \rho$. Let the $k$th joint inter-arrival time be denoted by $\tau_k := T^o_k - T^o_{k-1}$ with cumulative density function $F_{\tau_k}$. With (3.1), we can simplify the point process relation $$F_{\tau_{k+1}}(t) = 1 - \exp \left( - \int_0^t (\lambda T^o_k + s + \rho)\,ds \right) = 1 - \exp \left( - \frac{\lambda T^o_k}{\beta} (e^{\beta t} - 1) \right) e^{-\rho t},$$ which is the law of the joint inter-arrival times. ### 4. Simulation methods The law of the joint inter-arrival times in (3.2) can be used to derive a simulation method for extrinsic stress-release processes. To simulate we need to (i) generate $T^o_k$ joint inter-arrival times, and (ii) be able to attribute each arrival as being either a self-arrival from $N_t$ or an external arrival from $N^e_t$. By the inverse probability integral transform, we have $$\tau_{k+1} \overset{\mathcal{D}}{=} F_{\tau_{k+1}}^{-1}(U), \quad U \sim \mathcal{U}[0, 1],$$ where $\overset{\mathcal{D}}{=}$ denotes equality in distribution. The inverse $F_{\tau_{k+1}}^{-1}$ does have an analytic solution (which is somewhat rare) in terms of the Lambert $W$-function, so we can generate joint inter-arrival times by the inverse transform method. However, the Lambert $W$-function is relatively slow in many software packages, and this calculation does not perform the second attribution step. A faster alternative, which solves both problems at once, is to use the composition method. #### 4.1. Exact simulation of stress-release model The composition method [6, Section VI.2.3] simulates $\tau_{k+1}$ from two simpler independent random variables $\tau^{(1)}_{k+1}$ and $\tau^{(2)}_{k+1}$ by taking $$\tau_{k+1} \overset{\mathcal{D}}{=} \tau^{(1)}_{k+1} \land \tau^{(2)}_{k+1},$$ where the notation $\tau^{(1)}_{k+1} \land \tau^{(2)}_{k+1}$ is simply shorthand for $\min \{\tau^{(1)}_{k+1}, \tau^{(2)}_{k+1}\}$. One way to satisfy this relation is to choose $$\mathbb{P}(\tau^{(1)}_{k+1} > s) = \exp \left( -\lambda T^o_k \beta^{-1} (e^{\beta s} - 1) \right) \quad \text{and} \quad \mathbb{P}(\tau^{(2)}_{k+1} > s) = e^{-\rho s},$$ so $$\tau^{(1)}_{k+1} \overset{\mathcal{D}}{=} \frac{1}{\beta} \log \left( 1 - \frac{\beta}{\lambda T^o_k} \log (U_1) \right), \quad \tau^{(2)}_{k+1} \overset{\mathcal{D}}{=} -\frac{1}{\rho} \log (U_2), \quad U_1, U_2 \sim \mathcal{U}[0, 1].$$ This is the key step in the composition algorithm, presented in full in Algorithm 1.1. #### 4.2. Simulation by thinning Extrinsic stress-release processes can also be simulated via the thinning algorithm. The basic idea in this method is to generate a point process that has more arrivals than the model dictates, then probabilistically remove the excess points. The result can be computationally inefficient, and we compare the runtime of the thinning and composition simulation methods in Section 6. Algorithm 1.1: Generate an extrinsic stress-release process by composition. \textbf{Input:} start intensity $\lambda_0$, stress rate $\beta$, external arrival rate $\rho$, jump size distributions $F_X$ and $F_Y$, end time $T$ \begin{algorithmic}[1] \STATE \textbf{begin} \STATE Initialize $T^0_0 \leftarrow 0$, $\epsilon \leftarrow 10^{-10}$ or similar, $\lambda_e \leftarrow \lambda_0$, $i \leftarrow 0$, $j \leftarrow 0$, $k \leftarrow 0$ ; \STATE Simulate $r^{(1)}_{k+1}$ and $r^{(2)}_{k+1}$ via equation (4.1) and let $T^e_{k+1} \leftarrow T^e_k + r^{(1)}_{k+1} \land r^{(2)}_{k+1}$ ; \IF {$T^e_{k+1} > T$} \RETURN self-arrivals \{ $T_1$, \ldots, $T_i$ \} and, if desired, external arrivals \{ $T'_1$, \ldots, $T'_j$ \} \ENDIF \STATE Calculate $\lambda_{T^e_{k+1}} \leftarrow \lambda_{T^e_k + \epsilon} \exp(\beta(T^e_{k+1} - T^e_k))$ by (3.1) ; \IF {$r^{(1)}_{k+1} < r^{(2)}_{k+1}$} \STATE Update $i \leftarrow i + 1$ and $T_i \leftarrow t + r^{(1)}_{k+1}$ ; \textbf{\textit{\textsuperscript{Self-arrival}}} \STATE Simulate $X_i \sim F_X$ and update $\lambda_{T^e_{k+1} + \epsilon} \leftarrow \lambda_{T^e_{k+1}} \exp(-X_i)$ ; \ELSE \STATE Update $j \leftarrow j + 1$ and $T'_j \leftarrow t + r^{(2)}_{k+1}$ ; \textbf{\textit{\textsuperscript{External arrival}}} \STATE Simulate $Y_j \sim F_Y$ and update $\lambda_{T^e_{k+1} + \epsilon} \leftarrow \lambda_{T^e_{k+1}} \exp(-Y_j)$ ; \ENDIF \STATE Update $k \leftarrow k + 1$ and go to line 3 ; \STATE \textbf{end} \end{algorithmic} The first step in the thinning algorithm is to generate the $N'_i$ and $S'_i$ processes. The self-arrivals are then generated conditional on these external arrivals. Each self-arrival is generated sequentially and requires a local upper bound on the intensity process. If we know $S'_i$ for all $t \in \mathbb{R}_+$, we obviously have $$\lambda_t \leq \lambda_0 \exp(\beta t - S'_i), \quad t \in \mathbb{R}_+, \quad (4.2)$$ though as $t$ increases this becomes an extremely loose bound. However, if we also know the process $S_t$ up until time $\tau$, then $$\overline{\lambda}_{t|\tau} := \lambda_0 \exp(\beta t - S_{t\land \tau} - S'_i), \quad t \in \mathbb{R}_+, \quad (4.2)$$ is a much tighter upper bound on the intensity, at least for $t \in (\tau, \tau + \Delta)$ for moderately small $\Delta$. Figure 2 shows some example realizations of (4.2). With this definition, we can describe the thinning algorithm for the generalized stress-release process in Algorithm 1.2. In particular, line 5 of the algorithm uses (4.2) to find an upper bound of $\lambda_t$ over a small region $t \in (\tau, \tau + \Delta)$; these maximum values are not too tedious to find, as they occur either at the end time $\tau + \Delta$ or at one of the external arrival times $T'_j$ that arrives inside the region. Algorithm 1.2: Generate an extrinsic stress-release process by thinning. \begin{algorithm} \begin{algorithmic}[1] \State \textbf{Input}: start intensity $\lambda_0$, stress rate $\beta$, external arrival rate $\rho$, jump size distributions $F_X$ and $F_Y$, end time $T$, step size $\Delta$ \State \textbf{begin} \State \hspace{0.5em} Simulate the external arrivals $\{T'_1, \ldots, T'_N\}$ at rate $\rho$ by standard Poisson process methods; \State \hspace{0.5em} Simulate i.i.d. external jump sizes $\{Y_1, \ldots, Y_N\}$ from $F_Y$ and construct the $(S'_i)_{i \in [0,T]}$ process; \State \hspace{0.5em} Initialize $i = 0$, $t = 0$, $\epsilon \leftarrow 10^{-10}$ or similar; \State \hspace{0.5em} Set $M$ to be the maximum value of $\lambda_{t+i}$, cf. (4.2), over $s \in (t, t + \Delta]$; \State \hspace{0.5em} Generate a proposal self-arrival $T^* = t + E$ where $E \sim \text{Exp}(M)$; \State \hspace{0.5em} if $T^* > T$ then \State \hspace{1em} \textbf{return} self-arrivals $\{T'_1, \ldots, T'_i\}$ \State \hspace{0.5em} else if $T^* > t + \Delta$ then \State \hspace{1em} \textbf{end} \hspace{0.5em} \text{Reject the proposal, set } t \leftarrow t + \Delta, \text{ go to line 5} ; \State \hspace{0.5em} Sample $U \sim U[0, 1]$; \State \hspace{0.5em} if $U \leq \lambda_{T^*} / M$ then \State \hspace{1em} Accept the proposal: $i \leftarrow i + 1$, $T_i \leftarrow T^*$; \State \hspace{1em} Simulate a jump size $X_i \sim F_X$ and update $\lambda_{T_i+\epsilon} \leftarrow \lambda_{T_i} e^{-X_i}$; \State \hspace{1em} Set $t \leftarrow T^*$, go to line 5; \State \hspace{0.5em} else \State \hspace{1em} \textbf{end} \hspace{0.5em} \text{Reject the proposal: } t \leftarrow t + \Delta, \text{ go to line 5} ; \State \hspace{0.5em} \textbf{end} \State \textbf{end} \end{algorithmic} \end{algorithm} 5. The generator In this section we derive the explicit form of the infinitesimal generator for our process. With this we are able to find reciprocal moments, which are then used to confirm the validity of our simulation algorithm. 5.1. Constructing the infinitesimal generator Let us introduce the integro-differential operator $L^{st}$ of our extrinsic stress-release process $(\lambda_t, N_t, t)$, which acts on a function $f(\lambda, n, t)$ within its domain $\Omega(L^{st})$ as follows: $$L^{st}f := \frac{\partial f}{\partial t} + \beta \lambda \frac{\partial f}{\partial \lambda} + \int_{\mathbb{R}} [f(\lambda e^{-s}, n + 1, t) - f(\lambda, n, t)] F_X(dx) + \rho \int_{\mathbb{R}} [f(\lambda e^{-s}, n, t) - f(\lambda, n, t)] F_Y(dy).$$ (5.1) From Propositions II.1.16 & II.1.15 in [8], the conditional intensity function in equation (2.1) can be recast as $$\lambda_t = \lambda_0 \exp \left(\beta t - \int_0^t \int_{\mathbb{R}} x \mu(dx, ds) - \int_0^t \int_{\mathbb{R}} y \mu'(dy, ds)\right),$$ where $\mu$ and $\mu'$ are the jump measures associated with $S$ and $S'$, respectively. Their associated predictable compensators are $\nu(dx, dt) = F_X(dx) \lambda_t dt$ and $\nu'(dy, dt) = F_Y(dy) \rho dt$. We now state the following result. **Proposition 5.1.** Let the integro-differential operator for our stress-release process be defined as in equation (5.1). Then, for each $t \in \mathbb{R}_+$, we obtain $$\mathbb{E}[f(\lambda_t, N_t, t)] = f(0, N_0, \lambda_0) + \mathbb{E} \left[ \int_0^t L^{st}f(\lambda_s, N_s, s) ds \right]$$ if the following $f$-integrability conditions hold: $$\mathbb{E} \left[ \int_0^t \lambda_s ds \int_{\mathbb{R}} [f(\lambda_{s+}, N_s, s) - f(\lambda_s, N_{s-}, s)]^2 F_X(dx) \right] < \infty$$ (5.2) and $$\mathbb{E} \left[ \int_0^t \rho ds \int_{\mathbb{R}} [f(\lambda_{s+}, N_s, s) - f(\lambda_s, N_{s-}, s)]^2 F_Y(dy) \right] < \infty.$$ (5.3) Moreover, $f$ satisfies the following partial integro-differential equation: $$\frac{\partial f}{\partial t} + \beta \lambda \frac{\partial f}{\partial \lambda} + \int_{\mathbb{R}} [f(\lambda e^{-s}, n + 1, t) - f(\lambda, n, t)] F_X(dx) + \rho \int_{\mathbb{R}} [f(\lambda e^{-s}, n, t) - f(\lambda, n, t)] F_Y(dy) = 0.$$ (5.4) **Proof.** First note that $\lambda_t$ can be recast as $$\lambda_t = \lambda_0 + \int_0^t \beta \lambda_s ds + \int_0^t \int_{\mathbb{R}} \lambda_s (e^{-s} - 1) \mu(dx, ds) + \int_0^t \int_{\mathbb{R}} \lambda_s (e^{-s} - 1) \mu'(dy, ds).$$ Invoking Itô’s formula (see [13, Chapter VI]) on the arbitrary function $f(\lambda_t, N_t, t)$ yields $$f(\lambda_t, N_t, t) = f(\lambda_0, N_0, 0) + \int_0^t \frac{\partial f}{\partial s} ds + \int_0^t \frac{\partial f}{\partial \lambda} d\lambda_s + \sum_{0 < s \leq t} [f(\lambda_{s+}, N_s, s) - f(\lambda_s, N_{s-}, s)],$$ where $\lambda_t$ is the solution of the SDE given by $$d\lambda_t = \beta \lambda_t dt + \int_{\mathbb{R}} \lambda_t (e^{-s} - 1) \mu(dx, ds).$$ Hence, $\lambda_t$ is a martingale, and $$\mathbb{E}[f(\lambda_t, N_t, t)] = f(\lambda_0, N_0, 0) + \mathbb{E} \left[ \int_0^t L^{st}f(\lambda_s, N_s, s) ds \right].$$ This completes the proof. where \( \lambda^c \) denotes the continuous part of the semimartingale. We can write \[ \sum_{0 < s \leq t} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)] \\ = \sum_{0 < s \leq t} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)] \cdot \Delta N_s \\ + \sum_{0 < s \leq t} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)] \cdot \Delta N^c_s \] \[ = Q_t(f) + \int_0^t \int_{\mathbb{R}} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)] \nu(dx, ds) \\ + Q'_t(f) + \int_0^t \int_{\mathbb{R}} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)] \nu'(dx, ds) \] with \( Q(f) \) and \( Q'(f) \) being processes defined by \[ Q(f) := \int_0^t \int_{\mathbb{R}} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)](\mu - \nu)(dx, ds) \] and \[ Q'(f) := \int_0^t \int_{\mathbb{R}} [f(\lambda^c_s, N_s, s) - f(\lambda^c_s, N^c_s, s)](\mu' - \nu')(dx, ds), \] respectively. The integrability conditions in equations (5.2) and (5.3) guarantee that \( Q(f) \) and \( Q'(f) \) are square-integrable martingales [4, Theorem VIII of Chapter II]. Hence we conclude that the process \((f(\lambda_t, N_t, t))_{t \in \mathbb{R}^+}\) is a special semimartingale [17] which can be decomposed into a martingale and a predictable finite variation process \[ f(\lambda_t, N_t, t) - f(\lambda_0, N_0, 0) = Q_t(f) + Q'_t(f) + \int_0^t \mathcal{L}^{st}f(\lambda_s, N_s, s) \, ds \tag{5.5} \] Since \( Q(f) \) and \( Q'(f) \) are square-integrable martingales, the process defined by \[ \left( f(\lambda_t, N_t, t) - f(\lambda_0, N_0, 0) - \int_0^t \mathcal{L}^{st}f(\lambda_s, N_s, s) \, ds \right)_{t \in \mathbb{R}^+} \] is also a square-integrable martingale. Taking the expected value of both sides of equation (5.5) yields the result. For the subsequent expression, first define \( T > t \) and \( g_t := \mathbb{E}[h(\lambda_T, N_T, T) \mid t, \lambda_t = \lambda, N_t = n] \) for some function \( h \) such that \( g \) satisfies the \( g \)-integrability conditions (5.2) and (5.3). Then, by construction, \( g_t \) is a martingale. By similar arguments, we see that \( g - Q(g) - Q'(g) \) is a square-integrable martingale, but \( g - Q(g) - Q'(g) = \int_0^t \mathcal{L}^{st}g \, ds \) is also a continuous process with finite variation. It must therefore be a continuous martingale with finite variation [8, Corollary I-3.16]; hence we must have \( \mathcal{L}^{st}g = 0 \) \( \mathbb{P} \)-almost surely, which yields the partial integro-differential equation in (5.4). \( \square \) 5.2. Reciprocal moments Consistent with the observation in [21], we are unable to find moments of \( \lambda_t \) but we can find moments of its reciprocal. Throughout Sections 5.2 and 5.3 we assume that \( \lambda_0 = 1 \), though the same arguments can be made in the general \( \lambda_0 \) case. **Lemma 5.1.** Let \( m^S_1 := \int (e^x - 1) \, F_X(dx) \) and \( m^E_1 := \int (e^y - 1) \, F_Y(dy) \). We assume that \( \beta > \rho m^E_1 \) and \( \lambda_0 = 1 \). Then the expectation of \( \lambda_t^{-1} \) is given by \[ \mathbb{E}[\lambda_t^{-1}] = e^{-\psi_1 t} + \frac{m^S_1}{\psi_1} (1 - e^{-\psi_1 t}), \] where \( \psi_1 := \beta - \rho m^E_1 \). **Proof.** From Proposition 5.1, we have for \( f \in \Omega(\mathcal{L}^{sr}) \) that \[ f(\lambda_t, N_t, t) - f(\lambda_0, N_0, 0) - \int \mathcal{L}^{sr} f(\lambda_s, N_s, s) \, ds \] is an \( \mathcal{F} \)-martingale. Setting \( f = \lambda^{-1} \) in the generator yields \[ \mathcal{L}^{sr}(\lambda^{-1}) = -\beta \lambda^{-1} + m^S_1 + \rho \lambda^{-1} m^E_1 \] and \[ \mathbb{E} \left[ \lambda_t^{-1} - \lambda_0^{-1} - \int_0^t \mathcal{L}^{sr}(\lambda_t^{-1}) \, ds \right] = 0. \] Differentiating \( \theta_1(t) := \mathbb{E}[\lambda_t^{-1}] \) with respect to \( t \) yields the non-linear inhomogeneous ODE \[ \theta_1'(t) + \psi_1 \theta_1(t) = m^S_1, \quad \theta_1(0) = 1, \] whose solution is given in equation (5.6). By a similar token, and setting \( f = \lambda^{-2} \), we state the following. **Lemma 5.2.** Let \[ m^S_2 := \int (e^{2x} - 1) \, F_X(dx), \quad m^E_2 := \int (e^{2y} - 1) \, F_Y(dy). \] We assume that \( \beta > \rho m^E_2, \, 2\beta > \rho m^E_2 \), and \( \lambda_0 = 1 \). Then the expectation of \( \lambda_t^{-2} \) is given by \[ \mathbb{E}[\lambda_t^{-2}] = e^{-\psi_2 t} + m^S_2 \left\{ \frac{e^{-\psi_1 t} - e^{-\psi_2 t}}{\psi_2 - \psi_1} + \frac{m^S_1}{\psi_1} \left[ \left( \frac{1}{\psi_2} - \frac{e^{-\psi_1 t}}{\psi_2 - \psi_1} \right) - e^{-\psi_2 t} \left( \frac{1}{\psi_2} - \frac{1}{\psi_2 - \psi_1} \right) \right] \right\}, \] where \( \psi_2 := 2\beta - \rho m^E_2 \). We end this section by giving some recursive relationships related to the inverse moments of our process. Let \( \mathbb{N} \) be the set of natural numbers and let \( k \in \mathbb{N} \), \( m^S_k := \int (e^{kx} - 1) \, F_X(dx), \) \( m^E_k := \int (e^{ky} - 1) \, F_Y(dy), \) and \( \psi_k := k \beta - \rho m^E_k \). We further assume that \( k \beta > \rho m^E_k \). Then the generator for the function \( f = \lambda^{-k} \) is readily computed as follows: \[ \mathcal{L}^{sr}(\lambda^{-k}) = m^S_k \lambda^{k-1} - \psi_k \lambda^{k}. \] By the martingale property we have that \[ E \left[ \lambda_t^{-k} - \lambda_0^{-k} - \int_0^t L_s^{st}(\lambda_s^{-k}) ds \right] = 0. \] (5.8) Define the quantity \( \theta_k(t) := E[\lambda_t^{-k}] \), and differentiating equation (5.8) with respect to \( t \), we arrive at the recursive non-linear inhomogeneous ODE \[ \theta_k'(t) + \psi_k \theta_k(t) = m_S \psi_k (1 - e^{-\psi_k(t-s)}) \theta_k^{-1}(s), \] where \( \theta_0 \equiv 1 \), which can be solved in a recursive fashion to obtain further reciprocal moments. 5.3. Covariance process We provide an expression for the mean of the product of two reciprocals of intensities for our process. This can be used to compute the covariance process. For \( s < t \), it holds true that \[ E \left[ \lambda_t^{-1} \lambda_s^{-1} \right] = E \left[ \lambda_t^{-1} \lambda_s^{-1} \mid \lambda_s^{-1} \right] = e^{-\psi_1(t-s)} E \left[ \lambda_s^{-2} \right] + \frac{m_S}{\psi_1} (1 - e^{-\psi_1(t-s)}) E \left[ \lambda_s^{-1} \right]. \] (5.9) To see why this is true, note that the inner expectation can be computed as follows: \[ E \left[ \lambda_t^{-1} \mid \lambda_s^{-1} \right] = \lambda_s^{-1} E \left[ \lambda_t^{-1} \lambda_s^{-1} \right] = \lambda_s^{-2} e^{-\psi_1(t-s)} + \lambda_s^{-1} \frac{m_S}{\psi_1} (1 - e^{-\psi_1(t-s)}). \] Therefore, for \( s < t \), we have \[ \text{Cov} \left( \lambda_s^{-1}, \lambda_t^{-1} \right) = E \left[ \lambda_t^{-1} \lambda_s^{-1} \right] - E \left[ \lambda_t^{-1} \right] E \left[ \lambda_s^{-1} \right] = e^{-\psi_1(t-s)} E \left[ \lambda_s^{-2} \right] + \frac{m_S}{\psi_1} (1 - e^{-\psi_1(t-s)}) E \left[ \lambda_s^{-1} \right] - E \left[ \lambda_t^{-1} \right] E \left[ \lambda_s^{-1} \right]. \] where the remaining expectations are given by (5.6) and (5.7). Furthermore, when we set \( S' = 0 \) in equation (2.1), we retrieve the covariance results in [3, Theorem 2, page 317] upon substituting the results of Lemmas 5.1 and 5.2 to get an expression for equation (5.9) and subsequently subtracting the quantity \( E[\lambda_t^{-1}] \cdot E[\lambda_s^{-1}] \). 6. Numerical results To confirm that the simulation algorithms of Section 4 agree with the reciprocal moments derived in Section 5, we compare the first reciprocal moments given by the theory to Monte Carlo estimates. The results are given in Figure 3. The theory and the simulated values agree nicely. This example is also used to illustrate the speed benefits to the composition simulation method over the thinning method. In particular, Table 1 shows how long the two algorithms took to generate a fixed number of realizations of the extrinsic stress-release process. The difference in performance can be explained by (i) the fact that the composition method is easily vectorized while thinning is not, and (ii) the thinning algorithm is inherently inefficient as it intentionally generates too many points and discards a possibly large fraction of them. Exact simulation of extrinsic stress-release processes 115 FIGURE 3. First reciprocal moments $E[\lambda_t^{-1}]$ and second reciprocal moments $E[\lambda_t^{-2}]$ for $t \in [0, 50]$ of an extrinsic stress-release process with $\lambda_0 = 1$, $\beta = 0.25$, $\rho = 1.25$, and $X_i \sim \text{Exp}(3)$ and $Y_j \sim \text{Exp}(10)$. The theoretical values, given by (5.6) and (5.7), are compared with crude Monte Carlo estimates using the two simulation methods from Section 4. Both simulation methods were allocated the same amount of computation time (55–60 seconds); as such, Algorithm 1.1 generated 375 000 sample paths of $\lambda_t$, whereas Algorithm 1.2 generated 25 000. The shaded regions indicate the 95% confidence intervals of the Monte Carlo estimates. TABLE 1. Comparison of runtime (in seconds) to simulate a number of realizations of the extrinsic stress-release process until time $T = 100$ using Algorithms 1.1 and 1.2. The fastest time of three attempts is recorded. A grid search is performed to select the optimal step size $\Delta = 1.86$ for Algorithm 1.2 (this search is not included in the runtimes). The specification of the process ($\lambda_0$, $\beta$, $\rho$, etc.) is the same as in Figure 3. <table> <thead> <tr> <th>Algorithm</th> <th>$10^2$</th> <th>$10^3$</th> <th>$10^4$</th> <th>$10^5$</th> </tr> </thead> <tbody> <tr> <td>Composition</td> <td>0.0205</td> <td>0.0544</td> <td>0.3600</td> <td>3.2992</td> </tr> <tr> <td>Thinning</td> <td>0.3026</td> <td>3.0329</td> <td>30.761</td> <td>310.32</td> </tr> </tbody> </table> 7. Concluding remarks In this article we have introduced a straightforward but computationally efficient way of simulating exactly for a class of generalized stress-release process. The idea stems from the observation that between contiguous jumps at points in time, the process satisfies the continuous part of the semimartingale and is thus governed by an ordinary differential equation. This permits us to derive an expression for the distribution between events. The end result is that we are able to sidestep the need to resort to thinning algorithms for the simulation of this class of point processes. The explicit form of the infinitesimal generator for the extrinsic stress-release process is given. Theoretical reciprocal moments are derived which are then used to establish the validity of our simulation algorithms. We envisage that the approach outlined in this paper extends naturally to the general coupled stress release models, i.e. the linked stress-release model [1, 2] with appropriate structures satisfying the martingale generators. Ongoing work is investigating such a problem. Acknowledgements Young Lee is grateful to Professors Angelos Dassios and Louis Chen for inspiring discussions. An anonymous referee is thanked for his/her careful reading of an earlier version of the paper leading to a significant improvement of the presentation. Funding information Patrick J. Laub conducted this research within the DAMI – Data Analytics and Models for Insurance – Chair under the aegis of the Fondation du Risque, a joint initiative by UCBL and BNP Paribas Cardif. Hongbiao Zhao would like to acknowledge the financial support from the National Natural Science Foundation of China (#71401147) and the research fund provided by the Innovative Research Team of Shanghai University of Finance and Economics (#2020110930) and Shanghai Institute of International Finance and Economics. Competing interests There were no competing interests to declare which arose during the preparation or publication process of this article. Data The Python code used to generate the numerical results is available at https://github.com/Pat-Laub/exact-simulation-of-extrinsic-stress-release-processes. References
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From Colonial Policy to National Treasure: Tracing the Making of Audiovisual Heritage in the Philippines Bernadette Rose Alba Patino This study traces the history and construction of institutionalized cultural and audiovisual heritage in the Philippines and investigates how evolving views of heritage have shaped the country’s audiovisual archiving and preservation movement in the last fifty years. It examines the impact of naturalized definitions of heritage, as globalized by the United Nations Educational, Scientific, and Cultural Organization (UNESCO), and the implementation of audiovisual archival institution building, cultural policies, and archival priorities in the Philippines under the heritage banner set out by the organization. Considering the formation of what heritage scholars call “authorized heritage discourse” (AHD), this paper argues that a heritage hierarchy emerged in the country’s contemporary audiovisual archiving landscape, privileging an industrial view of cinema while marginalizing other forms of moving image practice. The study calls for an awareness of and resistance to institutionalized archives’ claims to social, cultural, and political power in their heritage construction and discourse. Keywords: audiovisual heritage, audiovisual archiving, authorized heritage discourse, Philippine cinema, UNESCO cultural policies Throughout the long history of the audiovisual archiving and preservation movement in the Philippines, a myriad of institutions, organizations, and individuals has wielded the concept of heritage to powerful effect. The phrase “save our heritage” as cultural policy and rallying point has propelled laudable actions like rescuing abandoned films, establishing a national film archive, and founding a regional Southeast Asian association of audiovisual archives. However, heritage has also been used to justify questionable practices like the creation of an industry-dominated film canon whose access is systematically corporatized and privatized; the launch of exclusive heritage preservation campaigns that, in a cruel twist of fate, have resulted in the marginalization, deprioritization, and deterioration of diverse forms of moving images; and even the inauguration of a building dedicated to the enrichment of cultural heritage amidst news of a cover-up on the death of numerous laborers during its hasty construction.¹ Those that employ the concept of heritage with such authoritative gusto rarely question it, simply assuming its naturalized, inherent value as a unifying force necessary for national cultural development—a convention that is maintained and ¹ Refers to an event or incident that occurred during the construction of a heritage site or building, involving laborers and raising questions about safety and transparency in construction processes. uncritically accepted within audiovisual archival institutions to this day, and not without certain material consequences. In the absence of a critical historical investigation of heritage in the field of audiovisual archiving in the Philippines, this paper seeks to trace the history and construction of institutionalized Filipino cultural and audiovisual heritage, particularly how naturalized notions of heritage shaped early initiatives to establish audiovisual archival institutions and what local and international factors led to contemporary definitions of audiovisual heritage to be rendered as a canon of primarily industry-made, feature-length narrative cinema, specifically in the past twenty-five years. Following scholar and moving image archivist Caroline Frick’s (2011) methodology of analyzing heritage as a socially constructed phenomenon, particularly her analysis on the role that the International Federation of Film Archives (FIAF) and the United Nations Educational, Scientific, and Cultural Organization (UNESCO) played in globalizing audiovisual materials as heritage, this study examines how both organizations impacted the Philippines’ audiovisual preservation and archiving movement as a result of their postwar policies that encouraged promoting cultural development, especially through a national cultural institution building, as essential to legitimizing the nation on the international stage. Heritage scholar Laurajane Smith’s (2006) notion of “authorized heritage discourse” (AHD), together with her examination of its origins and UNESCO’s policies as a product of AHD’s historical process and development, informs the paper’s analysis of heritage as cultural policy during the American colonial regime in the Philippines up to the dictatorship of Ferdinand Marcos. I argue that despite the varied definitions of audiovisual heritage and what constitutes the national as offered by pioneering audiovisual archivists, a hierarchy of audiovisual heritage emerged in the late 1980s following the closure of the Film Archives of the Philippines (FAP), the country’s first national-level audiovisual archive, at the height of the Marcos dictatorship and what was also UNESCO’s first foray into recommending and assisting in the establishment of such institutions in the global south. The exclusive hierarchy placed feature-length narrative cinema at the pinnacle and its restoration as the ultimate archival priority, reflecting an embrace of a primarily industrial view of both Philippine cinema and audiovisual heritage. While UNESCO played a significant role in instilling the heritage-as-national ethos in the Philippines and around the globe, the paper explores the layered and complex factors leading to the enduring hierarchy of audiovisual heritage that privileges an industrial view of cinema: the Marcos’ utilization of cinema as a highly politicized diplomacy tool; the failure and closure of martial law-era audiovisual archiving institutions; destabilized institution building in which centralized national-level audiovisual archives were historically structured within government agencies dedicated to film industry development; the subsequent deprioritization of audiovisual archiving and access vis-à-vis national film production and exhibition set as precedent; and the lack of laws strengthening the protection and preservation of and access to a diversified audiovisual heritage—all of which continue to impact the curatorial decisions and archival priorities by contemporary Filipino audiovisual archival institutions. A critical examination of the hierarchy and its development presented in this paper is necessary to understand the shortcomings of an exclusive audiovisual archival practice in order to move toward one that advocates and supports public and community-centric participation in the very creation of heritage, encompassing an awareness of and resistance to institutionalized archives’ claims to social, cultural, and political power in national heritage construction and discourse. Filipino Audiovisual Heritage in the Contemporary Landscape In 2012, the digitally restored versions of two Filipino films premiered in separate sections of the 69th Venice International Film Festival. To celebrate the festival’s 80th anniversary, the Retrospective section featured Manuel Conde’s 1965 film *Genghis Khan* among a roster of other such rare films archived at the Venice Biennale’s Historical Archives of Contemporary Arts (ASAC). In parallel, the Venice Classics, a section devoted to restored classics in world cinema, featured Ishmael Bernal’s 1982 film *Himala*. The premieres of the first-ever digitally restored films in Philippine cinema—both of which are considered masterpieces by two of the country’s National Artists for Film—garnered the same amount of attention and prestige as Brillante Mendoza’s film *Thy Womb*, an official selection in competition for the coveted Golden Lion that year. Together, the trio of films put on display on the global stage Philippine achievements in the cinematic arts. The inclusion of two restored Filipino “classic” films added a new dimension to the regular fanfare of a Filipino film selected to compete in an A-list film festival by calling attention to the greatness of the Philippines’ audiovisual heritage, a perception reintroduced into the public consciousness and added a patriotic flare and vital cultural capital to the films at hand. The restorations of *Genghis Khan* and *Himala* signaled a new era of audiovisual archiving in the country, in which digital film restoration of feature-length films dominates archiving activity and discourse, affecting not only public perception of audiovisual archiving and heritage but also professional norms in the field. Indeed, the grandiosity demanded by the concept of “heritage” was not lost on the two institutions that spearheaded the digital restorations, both of which currently hold the country’s largest audiovisual repositories. The Film Development Council of the Philippines (FDCP), a government arts body focused on developing the film industry, and ABS-CBN Corporation, the giant international media conglomerate, justify digital restoration of feature-length narrative films as an intrinsic, manifest step in the survival of Filipino audiovisual heritage and Philippine cinema itself. Since 2012, FDCP has organized multimillion-peso digital film restorations of approximately one title per year for a total of six restored feature-length films to date, while ABS-CBN leads with over 100 titles restored (Cruz, 2016), far outnumbering both analog and digital restorations carried out by various institutions in the past twenty years alone. Many may consider the influx of digital restorations in recent years a cause for celebration, but to unequivocally do so is to fail to recognize that the institutional fixation on restoration of a largely limited scope—primarily of industry-made feature-length films—is a symptom of a larger crisis: a severely parochial vision of what audiovisual archiving entails in practice and what audiovisual heritage encompasses in scope. FDCP spends well over half of its annual audiovisual preservation budget exclusively on film restoration of narrative feature-length films despite the fact that such films comprise barely a quarter of its entire collections, thereby casting aside the vast majority of its varied holdings in a variety of formats on celluloid, magnetic tape, and digital: short films, experimental and alternative works, documentaries, student and amateur films, wartime and martial law propaganda, as well as other such “non-film” films made for social utilization in different fields like education, medicine, sciences, sociology, and history. Moreover, the lack of financial investment, consistent experienced and knowledgeable leadership, and sheer political will to establish a permanent archival facility to house FDCP’s holdings—a crucial project that has languished for nearly a decade—continues to put all collections at risk. Such shortcomings render the vast majority of collections inaccessible to the public. Likewise, little has been done to address the idle progress in developing staff, infrastructure, and access points since the inception of FDCP’s archiving program in 2011. Meanwhile, as the main player in the private sector, ABS-CBN exclusively acquires feature-length films based on the potential of its commercial profitability and has systematically normalized the privatization of archival access (Cruzado, 2012). It cannot be left to compensate for the failures of state or independent archival institutions, despite its state-of-the-art facilities. It is no exaggeration to say FDCP and ABS-CBN’s partisan practices and priorities have dominated institutional audiovisual archiving in the Philippines for most of the last decade. Their priorities, zoomed in on feature-length film restoration, have had long lasting and arguably devastating effects on the overall state of audiovisual archiving in the country, especially considering that smaller government and private archives that once formed the core of the audiovisual preservation movement in the 1990s have already turned over many of their collections to either of the two institutions (Lim, 2013). The hegemony of industrial narrative cinema in contemporary audiovisual heritage discourse and archival practice puts into question whether or not the utmost purpose of audiovisual heritage is to nurture an authorized national identity and unity and passive black-box cinematic exhibition as the sole means for access and community engagement. FDCP and ABS-CBN accepted this archival model as an inherent, matter-of-fact truth, which begs for a historical investigation of how their naturalized notions of heritage and institutional priorities came to be and of what is at stake when archivists and archiving institutions take heritage for granted. The “Script” of Audiovisual Heritage and Archival Practice Scholar and moving image archivist Caroline Frick (2011) emphasized in Saving Cinema: The Politics of Preservation that “those involved in moving image preservation have not merely preserved movie history; they have, instead, actively produced cinematic heritage” (p. 5). She noted that “the preservation of so-called national or state heritage is not, and never has been, a neutral concept, although it is presented as such by politicians, the press, intellectuals, and archivists” (p. 19). Archival practices derive from institutions and archivists’ decision-making in specific cultural, political, social, and economic circumstances. Likewise in the Philippine context, by no means does the supposed innate value of heritage lead to the institutionalization of narrative cinema’s digital restoration as the principal focus of audiovisual archiving today, even though institutions describe it as an inherent and noble duty in the grand narrative of preservation. Assessing archives and archivists’ agency in choosing the roles and practices they adopt, Canadian archivists Terry Cook and Joan Schwartz (2002) developed the idea of “archival performativity,” observing that the practice of archives is the ritualized implementation of theory . . . it is a script formed by the ‘social magic’ of now-unquestioned, ‘naturalized’ norms. These norms are themselves generalized from past performances (practices) that archivists have collectively anticipated, over generations, would confer on them appropriate legitimacy, authority, and approval... for not to do so would undermine our professional identity, our sense of security, our comfort with our internalized scripts. Our scripts have thus become naturalized. (p. 173) Rather than question or dare to rewrite the script repeated over generations, FDCP and ABS-CBN choose to play the roles set out for them, leading to real material consequences in what does and does not get recognized as audiovisual heritage, and subsequently, in public accessibility, knowledge production, public participation in creating heritage, and claims to and uses of social and political power. Cook and Schwartz’s repeated “script” was given a historical dimension in heritage scholar Laurajane Smith’s (2006) notion of “authorized heritage discourse” (AHD). Tracing its roots to the development of nineteenth-century Western nationalism and liberal modernity, she defined AHD in her seminal work, Uses of Heritage: There is a hegemonic ‘authorized heritage discourse’, which is reliant on the power/knowledge claims of technical and aesthetic experts, and institutionalized in state cultural agencies and amenity societies. This discourse takes its cue from the grand narratives of nation and class on the one hand, and technical expertise and aesthetic judgment on the other. The ‘authorized heritage discourse’ privileges monumentality and grand scale, innate artifact/site significance tied to time depth, scientific/aesthetic expert judgment, social consensus and nation building. It is a self-referential discourse. (p. 4) Here, Smith (2006) laid out a number or characteristics of AHD: It institutionalizes interpretations of the past for the purpose of maintaining a hegemonic hierarchy of values according to what is valuable on the national scale; emphasizes the tangibility of heritage, whose management and conservation is limited to the realm of experts and professionals; and remains self-referential in that the very experts that manage heritage and measure its value also claim heritage to be innately valuable and profess so to the public. A close examination of FDCP and ABS-CBN’s archival practice—which insists on their exclusive authority on archival processes and priorities, the narrative that high-end digital restoration and exhibition is the ultimate tool to preserve the medium, and the definition of feature-length narrative cinema as the premier expression of national identity—reveals their adherence to AHD. How did AHD become the “script” in current institutionalized audiovisual archival practice? In the historical process of heritage making, Smith (2006) and Frick (2011) pointed to a specific international body that globalized the idea of national heritage beyond its European borders for the rest of the world to adopt: UNESCO. Across the globe, this organization played an integral role transforming the definition of moving image from a general artistic and historical document to the elevated, international status of national cultural heritage in its postwar conventions, charters, and recommendations (Frick, 2011). In the Philippines, UNESCO served as an optimistic consultant during the establishment of the first national-level audiovisual archive, leaving an indelible mark on the country’s audiovisual archiving and preservation movement and overall notions of what constitutes heritage. Cook and Schwartz (2002) stressed that “once we acknowledge ‘archival practice’ as a form of ‘performance’ of archives, we will be better able to become ‘performance conscious’” (p. 185). Only then can the archival institution understand its role and conceive of new models to participate in knowledge production, collective memory and remembering, and negotiating cultural, social, and political change in the present through new meanings of the past. **Historicizing Cultural Heritage: Enlightenment, Empire, and UNESCO** An early signatory of the UN Declaration in 1942, the Philippines, still under American rule as a Commonwealth, became one of the founding member states of the UN alongside 49 other nations when it signed its charter in 1945 following the end of WWII. Even with strengthened powers to impose and enforce sanctions, the UN took a dual approach, also making efforts to emphasize soft diplomacy through its specialized agency UNESCO, by cultivating knowledge and understanding between peoples toward a common humanity as a means of conflict prevention. The Philippines gained independence from the United States with the signing of the Treaty of General Relations on July 4, 1946, and joined UNESCO just four months later. In 1951 the Second Congress of the Philippines passed Republic Act (RA) No. 621, which established the Philippine National Commission for UNESCO, formalizing the country’s international commitment to the organization. Three decades of WWII reconstruction saw the proliferation of newly independent nations, causing a turning point in UNESCO’s evolving theoretical framework on culture: “The unique cultural identities of these nations, a justification for their independence and international existence, became a central political issue. The concept of culture was expanded to encompass ‘identity’ itself” (UNESCO, 2004b, p. 3). This marked a significant change from the immediate postwar years when UNESCO defined culture as historical and artistic production, though not specifically a representation of national identity. According to Frick (2011), by the 1970s heritage emerged in UNESCO’s theoretical framework as a valuable universal term needed to “better serve the articulation and exploitation of these varied, but specifically state-driven identities,” as UNESCO began insisting that “all countries, regardless of social, economic, or cultural status possessed a unique heritage” (p. 103). Heritage then in UNESCO’s policies evolved: it was not an immaterial concept but was intrinsically physical in form, meriting management, conservation, and preservation for posterity.5 Smith (2006) traced the origins of material heritage and its authorized discourse championed by UNESCO back to liberal modernity: Enlightenment rationality brought about the ideas of objective truth and the concept of civilizational progress, legitimizing the Europeans’ colonial and imperialist expansion by placing themselves at the pinnacle of the human advancement in technology, thought, and culture, as social Darwinism generated links that naturalized hierarchies along identity and race. Her study showed how museums, monuments, archeological expositions, and collections of antiquities became the trophies with which modern Europe educated its citizens and expressed its national identity, leading to a flood of legislation and policies for protection as “national heritage” throughout Europe, later emulated by the United States. With the collapse of imperial and dynastic powers, nation states needed “new devices to ensure or express social cohesion and identity to structure social relations . . . [and] methods of ruling and establishing forms of loyalty” (Hobsbawm, 1983, p. 263). The Philippines, the first country to have a nationalist revolution in Asia with the Philippine Revolution of 1896, has a long and rich history of nationalism dating back to the 1700s in resistance to Spanish colonial rule. How the burgeoning and evolving Filipino nationalism interacted with prevailing ideas of European material heritage through the Spanish and American regimes offers insights in future constructions of audiovisual heritage. The Spanish empire pioneered architectural conservation in order to protect material heritage in Europe, sponsoring such projects as early as the fifteenth century, later following French models in the nineteenth century to construct a material Spanish heritage after the Bourbons rule in Spain (Stubbs & Makaš, 2011). A lasting legacy of Spain’s vested interest in such architectural conservation is the multitude of Spanish structures, particularly churches and fortresses throughout the Philippine archipelago, since the Spaniards utilized architecture and demarcation of space to impose religious and colonial power as a means of control. In the Spanish caste system in the Philippines, notions of Spanish “heritage” as blood lineage was apparent in constructions of “Filipino” identity and racial hierarchy in society during the Spanish rule, though it was not until the final decades of the nineteenth century that the identification “Filipino” was “reappropriated by nationalists to refer to all those that suffered under the Spaniards and sought change through reform or revolution” (Rafael, 2000, p. 7). Filipino national symbols existed in smaller scale through emblems and flags, which were already common signifiers for sovereign states by the nineteenth century. The Filipino national identity and notions of cultural heritage went through further transformations under the U.S. regime, though not without contradictions stemming from the Americans’ tactical shift from military control to benevolent assimilation by the 1910s. Alongside impositions in the use of English as the language of instruction in schools, Americans pronouncedly imposed Western constructs of large-scale material heritage as a means to control the development of national identity in its new colony. Along with the reorganization of Spanish-era institutions today known as the National Museum, National Archives, and National Library, the Americans instituted a slew of legislation on the erection, protection, and conservation of various buildings, monuments, and sites reflecting Filipino national identity, though not without American interests in mind. To affirm their position as the new colonial power, by 1901 the American insular government passed Act No. 243, which declared land in Luneta as site for the construction of a monument of Dr. Jose Rizal, a leader of the propaganda movement who was murdered by the Spaniards and declared by the Americans a national hero, in the midst of the Philippine-American War merely three years after Spain ceded the Philippines to the US in the Treaty of Paris. This was followed by the 1908 Act No. 1856, to construct a pantheon of illustrious Filipinos; the 1918 Public Act No. 2760, to build, maintain, and improve national monuments, as well as to construct a monument to the revolutionary leader Andres Bonifacio; and the 1933 Executive Order (EO) No. 451, to create the Historical Research and Markers Committee (HRMC), responsible for marking historical antiquities in Manila and the rest of the country. With the establishment of the Commonwealth, which was considered a transitional government for the eventual formation of the Philippines as an independent nation, two more pieces of legislation on buildings, monuments, and sites as material heritage were passed: the 1936 Commonwealth Act No. 171, to conserve and restore Spanish colonial architecture in the District of Intramuros and replicate its style in the construction of new buildings, and the 1936 Commonwealth Act No. 169, to appropriate funds under the president’s direction for the identification, preservation, and acquisition of historic antiquities in the country. In a message stressing the importance of the latter Act, which was modeled after the U.S. American Antiquities Act of 1906, Commonwealth President Manuel Quezon (1936) stated: In our onward march to our national emancipation, we should not fail to look back to our past as a people so that we may be guided by its tested experience. It is, therefore, our duty not only to teach our children, and to point to the present as well as to the future generations, the heroic achievements of our forebears, the adventures they had lived as well as the mistakes they had committed, and the ideals for which they had cheerfully sacrificed their lives, but it is likewise our duty to preserve, to repair, to conserve and appropriately mark our historic antiquities and spot that abound in our country from Batanes to Mindanao. These historic antiquities are the sacred heritage of our ancestral traditions which so enhance the supreme worth of our people [emphasis added]. . . . the present and future generations may be impressed with the significance and value of those historic spots and antiquities, and that they may not be lost to posterity here and throughout the world. (para. 2-3) Significantly, Quezon echoed Western discourse on monument and site conservation and preservation of the time in a speech that marked one of the earliest known instances in which the concept of Filipino cultural heritage had been referred to as manageable objects, buildings, monuments, or sites warranting preservation. In line with Smith’s AHD, Quezon (1936) presented the “teaching” of all future generations of the greatness and “heroism” of the country’s forefathers through monuments and sites, as necessary means to legitimize the nation. Noting that material heritage “enhances the supreme worth” of the Filipino, Quezon viewed heritage as crucial for establishing national identity—the fulfillment of the Commonwealth’s duty to prepare for independence from the US. The barrage of building-, monument-, and site-focused legislation in order to construct a material heritage even at the inception of the American regime demonstrated how Western heritage concepts, primarily revealed through the transformation of public space, were imposed on the Philippines as institutionalized colonial policy. Up until the postwar years, the protection of heritage remained within national boundaries as the duty of the individual state. Heritage studies scholar Rodney Harrison (2015) named three particular events that shifted the perspective toward an international, global collaboration on safeguarding and managing cultural heritage: after WWII, UNESCO’s adoption of the 1954 Convention for the Protection of Cultural Property in the Event of Armed Conflict, which equated the targeting of cultural properties during conflict to the killing of civilians; the unprecedented international assistance given to the Egyptian government to relocate ancient Egyptian temples under the threat of flooding, even as the heritage rescue project led to the displacement of 100,000 people; and international alarm over the flooding of Venice shortly after the creation of The Venice Charter, which outlined conservation practices for buildings, monuments, and sites (pp. 300-301). The rhetoric of the “tragic loss of heritage” in the 1954 UNESCO Convention as well as the Egyptian and Venetian campaigns compelled the international community to take action, all the while solidifying and universalizing the narrative that “global cultural heritage” was constantly under threat. In turn in 1972, UNESCO adopted the groundbreaking Convention Concerning the Protection of the World Cultural and Natural Heritage (or the World Heritage Convention), which created the World Heritage List. This list contained nominated properties to protect for all humanity, according to a newly formalized, universal value system based on history, art, or science, and resulted in a global hierarchy of values (Harrison, 2015). The 1972 World Heritage Convention “institutionalized the nineteenth-century conservation ethic and the ‘conserve as found’ ethos” at the same time that heritage became “universally significant” (Smith, 2006, p. 27). Afterwards, international collaboration on heritage management, conservation, and preservation became a formalized priority for UNESCO member states. Cinema as Heritage and Cultural Policies under Marcos In UNESCO's shift to a global outlook following the 1972 Convention, “the notion of culture as political power took on added momentum by being attached to the idea of endogenous development” (UNESCO, 2004b, p. 4), entangling claims to identity with struggles for the distribution of resources in the international realm (Smith, 2012). Thus, the development of cultural heritage in service of projecting national identity became an accepted factor in legitimizing the nation on the global stage, which included institution building of national-level cultural entities among young nation states, in line with UNESCO's evolving views on heritage. While the 1972 Convention broadened parameters on what constitutes heritage from earlier definitions, its provisions did not initially encompass audiovisual materials. Frick (2011) noted that in the years leading up to the convention, the International Federation of Film Archives (FIAF), founded in 1938 by European and American institutions primarily motivated to elevate the status of films from entertainment to art, became a frequent collaborator of the organization. Although considered the respective national film archives within their own countries, FIAF’s founding members “only envisaged the history of the art of cinema in its universal dimension, and therefore it never crossed their minds to limit their film acquisitions to their national cinemas” (Dupin, 2013, para. 3). This reflected an internationalist outlook even before UNESCO adopted the concept in its framework. Interested in cinemas beyond their borders, FIAF became involved in “rallying archival interest” among nonmember states “due to the active film and television production in those areas and the corresponding lack of national repository” (Frick, 2011, p. 109). And their efforts to establish national repositories in collaboration with UNESCO would lead to the first national film archive in the Philippines, demonstrating how the globally accepted need to develop national culture in the postwar era, most especially among UNESCO member states, coalesced with the rise of audiovisual materials as part of a global cultural heritage. In the Philippines, the path toward the widespread recognition of audiovisual materials as cultural heritage and the establishment of national repositories proved more contentious than the construction of monuments and other national identity markers under the banner of heritage. By mid-century, cinema was widely perceived as a disposable commercial product, and while some major studios like LVN Pictures and Sampaguita Pictures began archiving their own films, others destroyed their films for silver reclamation or simply neglected them once their market value diminished (Domingo 1998; Diego 2010). Early Filipino pioneers in audiovisual preservation challenged the “entertainment only” perception of cinema much like their European and American counterparts, receiving dual support from UNESCO and from what journalist and author Primitivo Mijares called the “conjugal dictatorship” of Ferdinand and Imelda Marcos. The Marcoses pursued aggressive cultural policies in a bid not only to raise the international cultural heritage status of the Philippines but also in an attempt to intertwine national identity and heritage with that of their own. After Quezon during the Commonwealth era, Ferdinand Marcos was the next president who made extensive, long-lasting changes in cultural laws and institutions, which were influenced by the First Lady and later their daughter Imee. Notably, he was the first president to employ the term “heritage” in laws he approved as well as in his executive directives. EO No. 30, issued in 1966, created the Cultural Center of the Philippines (CCP), one of Imelda’s infamous pet projects. As per the order, one of CCP’s five purposes and mandates is “[t]o awaken the consciousness of our people to our cultural heritage, and to encourage them to assist in its preservation, promotion, enhancement and development” (Marcos, 1966). As CCP was mandated to handle music, performance art, and visual art, Pres. Marcos extended the definition of cultural heritage by law to encompass not only historical sites, buildings, and monuments but also diverse artistic fields and practices. In a speech delivered at the CCP in June 1970 for the Republic Cultural Heritage Awards Program, Marcos used the notion of heritage to justify and declare the need for cultural development through art: In order to come into our own, so to speak, we must now begin, more energetically than ever before, to deepen our culture, and take the best from our cultural heritage. Celebrating all things Filipino, in art, in music, in the dance, and in literature is only the beginning. We must also document our times, not only in the rigid framework of history, but against the larger horizons of the arts. I do not think that our final goal as a people and as a nation is to become an economically prosperous nation. I do not think we even desire to be a so-called world power, with military might to prove it. I do not think that we aspire alone to full stomachs, or a munificent industrial complex, or a well manicured suburbia. If I may say so, what we envision is a viable nation of freemen; yes, free, and that is important because it is only in that milieu that we can enrich the spirit, through unrestricted cultural development. . . . [W]e must do our best as well to nourish the Filipino spirit, to reveal its hidden beauty, to make it speak of its bright visions, and to build a precious legacy for other generations of Filipinos. Only when we have succeeded in nourishing well our spirit can we consider ourselves as a people fully realized. (Marcos, 1970, para. 15-19) For Marcos, cultural development through the arts expanded the definition of cultural heritage. He believed a broadened notion of heritage beyond the “rigid framework of history” advanced a pathway toward true national freedom—one that was spiritual rather than material. Even hunger was permissible as long as cultural heritage through art was used to strengthen a national Filipino identity toward the people’s actualization and enlightenment. The elitist, lofty, and nationalistic ideals of the dictator provided the core philosophy behind his regime’s self-serving and often contradictory cultural projects, ultimately at the expense of the Filipino people. Thus, Marcos’s vision of heritage as the pathway to a spiritual realization of the national demonstrates that AHD is not adverse oppressive governments, as it rhetorically posits heritage and national greatness as a noble pursuit for the benefit of posterity while weaponizing it for political purposes. Marcos’ declaration of martial law over the entire Philippines on September 21, 1972, through the signing of Proclamation No. 1081, transformed the country’s social, political, and economic fabric in profound ways, no less in media production and state-sanctioned cultural development. As Deocampo (1994) described it, > [A]ll forms of communication were suppressed and put under military control. All forms of dissent were strictly curtailed . . . By taking control of the media—cinema, television, radio, and print—the dictatorship could conveniently produce propaganda materials to enhance its image among the people. . . . Produced were films hailing the ‘New Society,’ the dictator’s ideological whims, the First Lady Imelda Marcos’ globe-trotting tours, and the fascist strength of the military. (para. 15) The aggressive measures in cultural policy that Marcos made early into his presidency returned as a juggernaut under martial law as his regime’s pursuit of cultural heritage development trudged forward, though not always in a singular direction. “National freedom” by way of cultivating cultural heritage would be achieved through selective and strategic state-sanctioned support for the arts, particularly film and architecture. Wielding culture, cinema, and heritage as tools of soft diplomacy and institutional nation building, the Marcoses appropriated UNESCO’s historical approach to conflict prevention in order to mask their abuses and elevate their image domestically and abroad. With the assistance of UNESCO, the regime initiated various audiovisual archiving projects to achieve their inflated goal of national freedom via cultural expression and heritage making to attain the spiritual enlightenment of the Filipino people. UNESCO and the Marcoses’ joint efforts culminated in the establishment of the country’s first-ever national-level audiovisual archive, the Film Archives of the Philippines (FAP), inside the walls of the so-called “film palace” known as the Manila Film Center. They supported the efforts of pioneering audiovisual archivists Benedicto Pinga and Ernie de Pedro, who offered diverse definitions of what constituted the national and audiovisual heritage, and worked toward cultural institution building as a means to realize the national. UNESCO and Marcosian Institution Building: The Film Archive of the Philippines Benedicto Pinga,\textsuperscript{10} president and founder of the Film Institute of the Philippines (FIP), which was formerly known as the Film Society of the Philippines (FSP),\textsuperscript{11} referred to a UNESCO conference excerpt in an undated report stating that “any country without at least one well-equipped archive is culturally underdeveloped” (Film Institute, n.d., p. 5). While the report did not clarify the UNESCO Conference being referred to, the mention of heritage as well as the necessity of a national film archive to indicate a nation’s cultural development made clear the international organization’s influence in the Philippines. According to the report, FIP aimed to revitalize the National Festival of Short Film in Manila, which had earlier editions in 1962 and 1964, believing that the project “could provide the stimulus for the preservation of Filipino documentaries as part of our cultural heritage and history” (p. 4). Pinga’s report is a rare instance in which film is discussed specifically as cultural heritage prior to the existence of film archives outside of major studios and pointedly perceives documentary film as a significant part of such heritage. Although the National Festival of Short Film was abruptly discontinued due to lack of funding, Pinga persisted in his advocacy to archive short films and documentaries by seeking to create a catalog of them (Specialized Cinema Producers of the Philippines, 1973). A 1967 article by Alejandro Roces in \textit{The Manila Chronicle} referred to FIP’s intent to publish a catalogue of 500 short films on “Philippine subjects” through the Board of Travel and Tourist Industry. Cataloguing efforts continued for nearly a decade according to the 1973 meeting minutes of the short film producers network, the Specialized Cinema Producers of the Philippines (CINEPRO), which was founded by Pinga and whose cataloging project was managed by Ernie de Pedro (Specialized Cinema Producers of the Philippines, 1973). By 1976 Pinga joined the Bureau of Foreign and National Information (BNFI) as a consultant to oversee “the systematic cataloging of all Filipino specialized films” (“Filipino films listed,” 1976). The following year, Pinga helped BNFI organize two conferences with the UNESCO National Commission of the Philippines: “Cataloguing and Preservation of Filipino Films” and the “First Convention on Film Preservation,” the latter gathering an array of government agencies, including the Marcos-run National Media Production Center, Association of Special Libraries of the Philippines, Philippine Universities Audio-Visual Center, Office for Civil Relations of the Armed Forces of the Philippines, Scientific Film Association of the Philippines, National Historical Commission, Bureau of Tourist Promotion, and Philippine Motion Picture Producers Association, and Board of Censors for Motion Pictures (Department of Public Information, 1977). This first collaboration with UNESCO in the field of audiovisual archiving across a multitude of sectors—film, tourism, military, academe—marked such joint projects as a priority for the Marcos regime and demonstrated its determination to institutionalize audiovisual heritage, eventually culminating in the establishment of the country’s first national film archive. By 1980 the General Conference of UNESCO in Belgrade, Yugoslavia, produced the Recommendation for the Safeguarding and Preservation of Moving Image, recognizing moving images as “an expression of the cultural identity of peoples, and because of their educational, cultural, artistic, scientific and historical value, form an integral part of a nation’s cultural heritage” (UNESCO, 2004a, p. 156) while emphasizing that moving images “should be preserved in officially recognized film and television archives and processed according to the highest archival standards,” with priority on “any part or all of their country’s national production” (p. 158). Ernie de Pedro, short film producer, amateur film collector, and historian, who acted as the cataloging head of Pinga’s CINEPRO, attended the General Conference in Belgrade after participating in the UNESCO’s First Convention on Film Preservation in Manila. His selection to lead the Philippine delegation came by referral due to his interest in archiving, according to his oral account at the Philippine Cinema Heritage Summit in 2013 (National Film Archives, 2013). In Belgrade, he joined the deliberations leading to UNESCO’s historic 1980 Recommendation, which widely defined moving image heritage to encompass various types of national productions in a multitude of formats as well as foreign productions that a country would consider as significant to its national identity (UNESCO 2004a). The Recommendation ensured that “the position of film as international heritage was ingrained, formally sanctioned, and accepted” (Frick, 2011, p. 111), providing an authorized foundation on which the audiovisual preservation movements around the globe was anchored. Upon De Pedro’s return to Manila from the UNESCO Conference, Imelda’s staff asked him to act as a consultant for a possible film archive, which officials at UNESCO Paris advised her to establish (National Film Archives, 2013). While the film industry resisted the idea of a national film archive due to sheer distrust of the government regarding the requirement for producers to deposit copies of their films, De Pedro noted that Pres. Marcos’ creation of a new agency—the Experimental Cinema of the Philippines (ECP)—changed their minds (National Film Archives, 2013). In January 1981, Pres. Marcos officially lifted martial law, though the gesture was superficial as martial law policies remained in place and he still held extralegal powers (Totanes, 1998, p. 241). He prioritized and strengthened the state’s involvement in the cultural sector, particularly in cinema, by issuing EO 640-A, which described the motion picture industry as “a truly dynamic and vigorous instrument for national cultural growth and development and vital social institution which will enhance the artistic as well as scientific heritage of the nation” (Marcos, 1981, section 1). The EO provided the guidelines for the promotion and enhancement of the preservation, growth, and development of the film industry, as well as amended the mandates of CCP to include the establishment of the Film Academy of the Philippines, Film Fund, Board of Standards, Manila Film Center, and Film Archive of the Philippines (FAP)—all of which would be under the helm of his wife. Amidst the mushrooming of new film-related institutions within CCP, he also created an independent one through EO 770: the ECP, a government-owned and controlled corporation tasked to produce and exhibit films and hold film festivals free from censorship. Film scholar Joel David (2010) noted that while the Marcoses were met with retaliation for their regime’s plethora of unforgivable abuses, “in answer mainly to foreign criticisms of martial rule’s repressive policies, Philippine cinema would act as their showcase of cultural democracy” (p. 232). National film production and exhibition became points through which the Marcos regime feigned images of cultural and national development and progress for the consumption of the international community. Upon the appointment of Imee Marcos as ECP’s head, it became apparent that the mandates of the new agency overlapped with that of CCP’s, particularly in the management and use of the Manila Film Center. For example, the Film Center served as venue for events, exhibitions, and film festivals of both CCP and ECP, and FAP, while formally under CCP, stored the productions of ECP in its film vaults at the Film Center. ECP, though more welcomed by film industry players and considered more dynamic in operation due to Imee’s stable leadership and its focus on film production and exhibition, was nonetheless mired with complex institutional politics on multiple levels due to the daughter’s desire to distance herself from “the vulgarities and excesses of her mother” (David, 2016, para. 12). Mother and daughter managed their projects separately. As David noted, the “MIFF [Manila International Film Festival] . . . was Imelda’s territory, as [was] the Film Archives of the Philippines (FAP)” (p. 235). Under the helm of Imelda, FAP and archiving initiatives diminished in the shadow of the MIFF. The country’s first international festival garnered strong international appeal and attention given its infamously luxurious and Hollywood-star-studded opening coinciding with the inauguration of the Film Center, despite an earthquake and a construction accident that led to the death of over one hundred of laborers. Within CCP and ECP’s intertwined mandates championing the development of cinematic heritage as a duty of the state, national film production and exhibition took precedent over audiovisual archiving and preservation. At the overshadowed FAP, Imelda appointed De Pedro as its inaugural director-general, upon UNESCO’s recommendation (National Film Archives, 2013). A historian by training, he took interest in short turn-of-the-century films about the Philippines prior to his stint as FAP’s director-general and even purchased collections of such works as a collector prior to his appointment (National Film Archives, 2013). Under his directorship he emphasized the value of such short historical films, as FAP collected works “not only those acclaimed for their artistic achievement but also those which serve as a chronicle of changing values and aspirations” (Rodriquez, 1982, p. 11), “dating back to the introduction of cinema and television in the Philippines” (Nicolas, Jr., 1982, p. 16). Under his directorship, FAP focused its archival efforts on at-risk short historical works, especially those made at the advent of cinema, including works produced by the Philippines’ colonizers when the limits of the medium were continually transforming and the films produced offered complex notions of the national in the transition between the Spanish to American colonial regimes. De Pedro, like Pinga, aligned “specialized cinema,” that is, short films, historical films, and documentaries, with audiovisual heritage. In a show of support for the construction of FAP within the Manila Film Center, UNESCO dispatched as technical consultant Christopher Roads of the International Council for Film and Television Audiovisual Communication (ICFT), the organization’s advisory body on audiovisual media. In his report on the project, he proclaimed that “of the hundreds of Philippine films made before 1951 not one has survived in the country” (Roads, 1981, p. 2), and this dire situation represented “few more striking, if tragic, testimonies for the need for archival facilities could be imagined” (p. 2). He revealed that UNESCO intended to use the Film Center as a model to develop film archives in the global south: The Manila National Film Centre [sic] could serve as a possible pilot archive where new techniques for the long-term preservation of moving image media particularly suited to the needs and circumstances of the developing world can be evolved . . . it is to be hoped that [it] will make a significant international contribution to the ability of future generations, perhaps thousands of years from now, to see and appreciate the twentieth century’s remarkable heritage of moving images. (p. 7) In UNESCO’s view, FAP and the Film Center made significant steps forward for the development not only of Filipino cultural heritage but also of all humanity and the reaches of posterity, reflecting the globalized turn of heritage management and preservation. After three years, thanks to the technical expertise of Roads and the dedication of De Pedro, FAP was on the verge of receiving formal recognition from FIAF as a national film archive (Domingo, 1998, p. SE-4), which would have been a first for Southeast Asia. However, despite the lofty ambitions of the Marcoses and support from UNESCO in establishing an institutionalized audiovisual archive, FAP met an early demise after just four years of operation—and with it, Pinga and De Pedro’s support for the inclusion of diverse short, historical, and documentary works as audiovisual heritage—due to the Marcos ouster in 1986 after the People Power Revolt. David (2016) noted that the ECP closed in 1985 because of the “technicality” of Imee’s resignation—she wanted to focus on her legislative responsibilities, so most of the functions of ECP were transferred to the CCP and the newly established Film Development Foundation of the Philippines, the precursor of the FDCP, which focused on promotions and incentives for the film industry’s growth. As for the film archive, De Pedro, like Pinga, out of his own efforts, found ways to continue audiovisual archiving projects by creatively funding FAP for another three years until 1989 (National Film Archives, 2013). However, FAP’s sporadic funding did not last and the Movie and Television Review and Classification Board (MTRCB), a censorship body created in the twilight years of the Marcos regime, officially absorbed the government’s film archiving responsibilities, following a provision created prior to FAP’s closure that required the master negatives of all rated films be deposited to the review board. As MTRCB lacked proper archival facilities, many of FAP’s audiovisual holdings were scattered among various government institutions, handed back to private collectors, or left in the basement of the abandoned Film Center. Debates went on for nearly a decade on “whether the MTRCB is the proper place for an archives division” (Miranda, 1997, p. 23) due to the concern that a censorship body’s primary duty is to alter films for commercial exhibition, not to archive or preserve them. While MTRCB’s archiving division eventually closed, the transfer of audiovisual archival duties to the censorship body solidified years of constructing audiovisual heritage around feature-length narrative cinema. This marked a notable departure from Pinga and De Pedro’s investment in short, historical, and documentary works, which were soon marginalized in the dominating discourses surrounding audiovisual heritage following the end of FAP. FAP’s unceremonious termination exposed the extent to which audiovisual archiving was devalued within the chaotic structure of CCP and ECP, whose institutional prioritization consistently eclipsed the functions of the FAP. While CCP and ECP’s film production, exhibition, and film festival programs at the Manila Film Center were retained and undertaken by government bodies mandated by law to carry out such cultural work, the national film archive did not have the same trajectory. The ensuing destabilization and eventual decentralization of archival institutions paved the way for shortsighted curatorial and archival practice based on a naturalized audiovisual heritage hierarchy that privileges an industrial view of cinema. **Naturalizing the Industrial View of Audiovisual Heritage** Over the next two-and-a-half decades, the closure of the state-initiated FAP led to an “era of cooperation and collaboration in a decentralized archival advocacy among the largest remaining audiovisual archives in the country” (Lim, 2013, p. 16), including the participation of the following institutions: CCP, Philippine Information Agency (PIA), University of the Philippines Film Institute (UPFI), Mowelfund Film Institute (MFI), LVN Pictures, Sampaguita Pictures, and ABS-CBN Corporation, with the National Commission on Culture and the Arts (NCCA) providing occasional support for film restoration projects. Many audiovisual archives within the network, particularly government, academic, and independent members, faced the same perennial problems that FAP never managed to overcome: lack of funding and facilities, deprioritization as sub-departments of parent agencies, and institutional instability. Largely ignored by the state, the network’s members, namely UPFI and MFI led by PIA and CCP, had to seek international support through the Association of Southeast Asian Nations (ASEAN). The sense of ASEAN regional audiovisual archiving was born together with a need to formalize the nodal audiovisual network in the Philippines, following the 1993 Conference and Workshop on ASEAN Audio/Video Film Retrieval, Restoration, and Archiving in Manila. The archival network officially registered as a non-profit and non-governmental organization called the Society of Filipino Archivists for Film (SOFIA) the same year and played a central role in the founding and launching of the South East Asia-Pacific Audiovisual Archive Association (SEAPAVAA) by 1996, with the Philippines taking the lead in audiovisual archiving in the ASEAN region. SOFIA’s momentum soon transformed into a campaign and decisive actions toward the reestablishment of a national film archive. SOFIA worked closely with the National Film and Sound Archive in Australia (NFSA), a fellow SEAPAVAA member and an institution closely involved with UNESCO, in planning the Philippines’ national film archive in 1996. However, changing political tides at the national level—that is, the ouster of former President Joseph Ejercito Estrada—eventually ended support for the project in 2001, similar to how Marcos’ ouster led to the downfall of FAP. The sudden and lackadaisical disposal of films by LVN Pictures, a major studio and driving force of the film industry during the so-called “golden age” of Philippine cinema in the postwar era, spurred SOFIA into action in 1994, solidifying the hierarchal organization of audiovisual heritage post-FAP by continuing to prioritize feature-length narrative cinema. Professor Clodualdo del Mundo, Jr. (2004), former SOFIA president, recounted how the organization’s founding members had rushed to an outdoor basketball court where LVN dumped thousands of film cans: “Passionate archivists hoped that they could find little treasures in the mountain of films . . . and listed 24 titles as top priority for rescue” (p. 16). The incident spurred SOFIA to pen a document titled “Draft Elements for a Master Plan to Save the Philippines’ Film Heritage,” which cited that the organization “was called upon by the film industry to draft a master plan for the development of film” (Mendoza, 1994, p. 1). By 1997, PIA and SOFIA presented to NCCA a project proposal that listed 19 films for restoration and cleaning, and proclaimed the titles to be of “high heritage value” based on the following criteria: “endangered Filipino film classics whose survival is in immediate risk unless promptly restored; films that are sociologically, culturally, historically and artistically significant; landmark films or sample films of a specific genre” (as cited in Lim, 2013, p. 19). The list, primarily consisting of feature films directed by National Artists and those produced by major studios, reflected the AHD value system in which the heritage curation process embraced an industrial view of cinema, perceiving it to best service national identity formation out of all other forms of moving image practice. Although SOFIA members inspected and inventoried their highly diverse collections comprising of short films and videos, experimental and student films, documentaries, historical footage, and other orphaned works, feature-length narrative film restoration became the centerpiece of their archival practice in their attempts to achieve a broad base of support to reestablishing a national film archive. This demonstrated how the necessity of national-level institution building remained the marker of national cultural development. Likewise, emphasis on restoring and exhibiting feature-length narrative cinema became a convenient way to attract a wider audience for their advocacies, especially from the film industry itself. Their efforts to professionalize audiovisual archiving through SEAPAVAA workshops and international training seminars, while constructive on the small scale, did little to address deep-seated archival infrastructure and funding problems. For SOFIA, film restoration and exhibition were deemed as more realistic goals, considering that long-term preservation, much less any other forms of access, was impossible in resource-strapped and deprioritized archival entities. The hegemony of restoring feature-length narrative cinema in archival practice reflects SOFIA's adoption and naturalization of a hierarchy that privileges an industrial view of the medium. UNESCO's heritage-as-national ethos as well as the repercussions from Marcos-era state-sanctioned cultural policies provided the outline for SOFIA's audiovisual archiving script, which they inherited and chose to follow in their curatorial and archival practices. This script has always been premised on the inherent need to protect and preserve audiovisual heritage toward national identity formation, enlist a circle of experts to define and defend a heritage canon that fits the state's prevailing definitions of the national, and return to national-level institution building by calling for the reestablishment a national film archive. Advocating for the feature-length narrative film as the highest expression of audiovisual heritage and restoration as prioritized archival practice, SOFIA solidified a specific film canon of primarily industry-produced titles as representative of audiovisual heritage, thus setting the precedent that would be followed by FDCP and ABS-CBN years later after the two institutions acquired many of the collections formerly held by SOFIA members. The script determined that cinematic fictions in the linear, feature-length, narrative form hold the highest position in the audiovisual heritage hierarchy, given such fictions' power to engender national self-consciousness through storytelling, providing “templates through which history can be written and national identity figured” (Shohat & Stam, 2014, p. 102); that the institutionalized national film archive project feature-length narrative films “as national accomplishments, as conveyors of cultural identity” (De Vlack, 2007, p. 24); and that any other goal beyond contributing and servicing the authorized national narrative remain peripheral. The NCCA attempted to address problems faced in national cultural heritage preservation through the National Cultural Heritage Act of 2009, which was the culmination of decades of heritage management laws modeled after UNESCO’s conventions that supported the monolithic use of cultural heritage “in pursuit of cultural preservation as a strategy for maintaining Filipino identity” (“National Cultural Heritage Act,” 2009, para. 2) and protections for declared cultural properties. However, a perceivable gap remains in the attention given to audiovisual heritage. Sections 31 and 32 of the Act outline the designated national cultural agencies and institutional linkages tasked with the designation, categorization, and assessment of national cultural properties and treasures. Of the eighteen government bodies listed, none of them hold the specific responsibility of assessing audiovisual materials as cultural property or national cultural treasures, thus excluding said materials formal recognition, protection, and privileges under the law. Clauses that contain catch-all phrases in Section 5, such as the declaration that “works by national artists” or “all archival materials or documents older than fifty years” (National Cultural Heritage Act, 2009, para. 7) are automatically considered important cultural properties, are ineffective, given audiovisual materials’ sheer lack of representation under the designated government bodies. Such conditions deter possibilities to create more inclusive definitions of audiovisual heritage, and points to the continued dominance of the industrial view of audiovisual heritage in the foreseeable future and the ironic failure of institutionalized AHD in the Philippines to fulfill baseline preservation objectives. Conclusion Cultural heritage as expressed in policies during the American colonial regime up to the Marcos dictatorship fostered the naturalization of Western models of AHD as proof of national cultural development by defining heritage as a manageable and tangible set of objects with fixed meanings; privileging grand expressions of national identity; guarding a closed circle of heritage gatekeepers; and claiming the necessity of national-level cultural institutions, however bereft of effective archival practice. All of these models continue to persist today. Smith (2012) warned that AHD is far from passive, wielding authority to “regulat[e] and govern the political and cultural meaning of the past” (para. 7) so that “the assumed meaning in inherent heritage, and the past and culture it represents, will not be changed or challenged” (para. 16). She noted that AHD suppresses subnational or community-determined views of heritage that resist and question authorized ones, fails to acknowledge AHD embedded in public policy since heritage “just is,” and ensures that dominant institutions’ values and knowledge are universalized and formalized by certified experts. In the Philippines, decades of prioritizing and institutionalizing an authorized curation of what constitutes the national within audiovisual heritage have limited and constrained potentialities in the meaning and uses of such heritage. To break free of such constricting authority, archivist Verne Harris (2001) advocated that those in the profession must become aware of their position and resist power—even their own—from within the institution by “listen[ing] intently for the voices of those who are marginalised or excluded by prevailing relations of power” (p. 11). Examining the history of constructing Filipino heritage and its influences on audiovisual archiving and preservation presents an opportunity to reassess the archival mission itself, such that it may be challenged and transformed. Archival practices must translate into critical engagement well beyond the institution, with the goals of renegotiating, disrupting, and diminishing boundaries of authority, all the while cultivating community-initiated and independent audiovisual archiving initiatives, transparent accessibility of the archival entities, and diverse participation of those who define what constitutes audiovisual heritage. References Film Development Council of the Philippines. (2014). *National Film Archives of the Philippines annual report*. Manila: Author. Film Institute of the Philippines. (n.d.). *Brief study on the National Festival of Filipino Documentaries*. Manila: Author. Notes 1 See footnote 13. 2 FDCP’s digital restoration projects include (in order of completion) Genghis Khan (1965), Maynila sa Mga Kuko ng Liwanag (1975), Insiang (1976), A Portrait of the Artist as Filipino (1965), Pagdating sa Dulo (1971), and most recently, Zamboanga (1936). 3 For statistics on the holdings of FDCP see Film Development Council of the Philippines (2014). For a summary of its collections, see footnote 14. For budget allocation to film preservation see Department of Budget and Management (2016). 4 As noted by Lim (2013), the turnover of collections of smaller institutions is due to the fact that FDCP and ABS-CBN Film Archives are the only audiovisual archives in the country with (a) open acquisition policies and (b) 24/7 climate-controlled vaults. In sum, FDCP adopted audiovisual collections from different government agencies through Administrative Order No. 26, including those from the Philippine Information Agency, University of the Philippines Film Center Film Archive, Historical Commission of the Philippines, Movie Television Review and Classification Board, and Intramuros Administration. Through voluntary deposit, it also contains collections from independent and private entities like the Mowelfund Audiovisual Archive, Goethe Institute Manila, Sampaguita Pictures, Premiere Productions, Unico Pictures, Mandarin Laboratory, SQ Film Laboratory, and individual filmmakers and producers. ABS-CBN Film Archives holds all Star Cinema productions as well as feature-length film titles acquired for restoration and rerelease. These include titles produced by a myriad of production companies as well as those sourced from different public and private entities such as the Cultural Center of the Philippines. For details on FDCP and ABS-CBN’s collections and acquisition policies, see Film Development Council of the Philippines (2014) and Cruzado (2012). Beyond FDCP and ABS-CBN, private and independent entities such as Regal Films and FPJ Film Archives maintain their own archives. 5 Smith (2006) noted that the 2003 Convention for the Safeguarding of the Intangible Cultural Heritage emerged only when non-Western nations criticized the 1972 World Heritage Convention’s exclusion of such heritage (p. 28). 6 The Spanish regime initially established the National Museum, National Library, and National Archives, the first two by Royal Order No. 689 in 1887 and was then called the Royal Museo-Biblioteca de Filipinas. The last one existed as the Spanish Division of Archives since at least the 1700s. During the American Commonwealth era, the Institute of National Language was established in 1936 by former president Manuel Quezon through Act No. 184. While under the Americans, the transformation of public space remained the central mode of instilling a sense of heritage through materials means. The National Museum, National Library, and National Archives went through numerous stages of reorganization under the Americans, less prioritized for projecting Filipino national identity but more entangled with formalizing American bureaucratic administrative functions. These early cultural institutions were modeled on well-established Western norms of authorized expressions of national identity. 7 The HMRC is the precursor to today’s National Historical Commission of the Philippines. 8 On the remaining domestically-produced films since 1897, the Society of Filipino Archivists for Film (SOFIA) noted that the early producers' destruction and neglect of these films are the cause of their low survival rate (Domingo, 1998; Diego, 2010). 9 Following Pres. Quezon's use of the term “heritage,” his successors also used the term in their speeches and written messages, though not in laws or executive directives they signed. 10 Refer to Deocampo (2011) and Lim (2013) for biographies of Benedicto Pinga. 11 FSP was considered “the first underground film group in the country” (Samonte, 1986, p. 20) whose members produced some of the earliest experimental Filipino films, reflecting Pinga's preoccupation with what he calls “specialized films” beyond the standard narrative feature-length commercial fare. 12 The Recommendation broadly defines three categories of moving images: “(i) cinematographic productions (such as feature films, short films, popular science films, newsreels and documentaries, animated and educational films); (ii) television productions made by or for broadcasting organizations; (iii) videographic productions (contained in videograms) other than those referred to under (i) and (ii) above” (UNESCO 2004a). Furthermore, it defines moving image heritage as follows: “All moving images of national production should be considered by Member States as an integral part of their ‘moving image heritage’. Moving images of original foreign production may also form part of the cultural heritage of a country when they are of particular national importance from the point of view of the culture or history of the country concerned” (UNESCO 2004a). 13 The first Manila International Film Festival opening and the simultaneous inauguration of the Manila Film Center pushed through despite an accident during construction that trapped numerous laborers in cement. As the former first lady allegedly made the decision to bury the laborers on site in order to meet the construction deadline, the Marcoses justified developing cultural heritage in exchange for human life, not unlike the earlier UNESCO project that led to the displacement of 100,000 people for the sake of saving ancient Egyptian temples. Refer to David (2016) for details on MIFF’s controversies. 14 See Del Mundo (2004), Lim (2013), and Society of Filipino Archivists (2014) for the full list of films. 15 Led by the NCCA, these include the Cultural Center of the Philippines, National Archives of the Philippines, National Library, National Historical Institute (now the National Historical Commission), National Museum, Komisyon sa Wikang Filipino, Department of Tourism, Intramuros Administration, Department of Education, Department of Public Works and Highways, National Commission on Indigenous Peoples, Department of Environment and Natural Resources, Department of the Interior and Local Government, Office on Muslim Affairs, UNESCO National Commission of the Philippines, Housing and Land Use Regulatory Board, Autonomous Region in Muslim Mindanao and the Cordillera Administrative Region, and the Office of the Special Envoy on Transnational Crimes ("National Cultural Heritage Act," 2009). While the National Archives of the Philippines is responsible for overseeing significant archival materials, it lacks the facilities to maintain its own collections of audiovisual materials and has not engaged in official coordination with any of the audiovisual archiving institutions in the country regarding the assessment of audiovisual materials as cultural property and/or treasure in line with the 2009 Act. BERNADETTE ROSE ALBA PATINO served as an audiovisual archivist at the Philippine Film Archives (formerly the National Film Archives of the Philippines), under the auspices of the Film Development Council of the Philippines, after receiving her degree in Slavic Languages and Literatures from Indiana University. In fall 2018, she will begin pursuing her MS in Library and Information Science at the Pratt Institute School of Information in New York City. (corresponding author: bpatino@pratt.edu)
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INTEGRAL-EQUATION ANALYSIS OF FREQUENCY SELECTIVE SURFACES USING EWALD TRANSFORMATION AND LATTICE SYMMETRY J. X. Su*, X. W. Xu, M. He, and K. Zhang Department of Electronic Engineering, Beijing Institute of Technology, Beijing 100081, China Abstract—In this paper, we present the space-domain integral-equation method for the analysis of frequency selective surfaces (FSS), consisting of an array of periodic metallic patches or a metal screens perforated periodically with arbitrarily shaped apertures. The computation of the spatial domain Green’s function is accelerated by the Ewald transformation. The geometric model is simplified by the lattice symmetry, so that the unknowns are greatly reduced. Time of filling MOM matrix and solving linear system is dramatically reduced. Our technique shows much higher efficiency when compared with the available commercial software and the existing methods published. 1. INTRODUCTION The frequency selective surfaces (FSS) often consist of an array of periodic metallic patches or a conducting sheet with periodical apertures. It provides uninhibited transmission in specific frequency bands while suppressing transmission in other bands when illuminated by an incident electromagnetic wave. They have found a variety of applications in a broad range of the electromagnetic (EM) spectrum including antenna reflectors, quasi-optical filters, polarizers, switches, and designing more efficient lasers [1]. Recently, it has been shown that periodic structures built from nonmagnetic conducting sheets can exhibit negative real parts of permittivity and permeability [2]. These materials, designated as left-handed metamaterials, are opening new application fields. Periodic structures are advantageously analyzed with integral-equation (IE) techniques, usually formulated in the spectral domain, as exemplified by the case of multilayered FSS [1]. Two approaches can be employed. One is to compute a specific FSS in its entirety [3], the other is to cascade the generalized scattering matrices (GSMs) of the constitutive building blocks [4]. In using the MoM, the appropriate choice of basis function is very important. The entire domain basis functions are often used to analyze the specific geometry, such as dipole, square and so on. For complex shape geometry, subdomain basis functions such as rooftop basis functions [5] and Rao-Wilton-Glisson (RWG) basis functions [6] have to be used. Generally, the former is only utilized to analyze the canonical geometry FSS, and the later is utilized to analyze the arbitrary geometry FSS for its ability to model arbitrarily shaped structures. Therefore, spatial domain integral-equation analysis of periodic structures using RWG basis functions becomes a popular technique. The application of the Floquet-Bloch theorem [7, 8] reduces the computational domain of infinite periodic structures to a single unit cell but leads to the result that involves the numerical evaluation of very slowly converging series. A number of techniques, either analytical or numerical, have been developed to accelerate the convergence of the relevant series. Among the analytical ones, Poisson's formula and Kummer's decompositions [9] represent the most commonly adopted approaches. Numerical acceleration techniques like the Shanks’ transformations [10] or the \( \rho \) algorithm [11] may also be necessary to further accelerate the result. Improved convergence can be obtained by applying the Ewald’s transformation [12]. Compared to the other acceleration techniques, Ewald method converges fastest (Gaussian convergence) and is the most accurate when the observation point gets close to the sources. Recently, space-domain integral-equation method [13, 14] and hybrid finite-element/boundary-integral (FE/BI) method [15], using the Ewald transformation to accelerate the convergence of PGF, have been applied to analysis of three-dimensional doubly periodic structures based on arbitrary non-orthogonal lattice configurations. In this paper, we propose a spatial-domain integral-equation method for the analysis of frequency selective surfaces (FSS) using Ewald transformation and lattice symmetry. The involved PGF are computed using the Ewald transformation to accelerate their convergence. This paper first presents integral-equation method analysis of periodic structure with lattice symmetry, simplifying geometry model of unit cell. Typically, the lattice configuration of periodic structure has good symmetry. If we use the lattice symmetry to simplify the unit model, the unknowns will be reduced greatly, so that the solving time of MoM linear system and the matrix-filling time are reduced dramatically. Two new basis functions deriving from RWG basis function are introduced to deal with the current condition of the unit patch. This technique will be demonstrated in detail in Section 5. This paper is organized as follows. Firstly, integral-equation method is described and two new basis functions are introduced. Secondly, Ewald transformation of periodic Green’s function (PGF) and singularity extraction are described. Thirdly, the technique using lattice symmetry to simplify the geometry model is proposed to analyze periodic structure efficiently. Finally, some numerical examples are presented to illustrate the efficiency of our approach. 2. INTEGRAL EQUATION We consider a frequency selective surface with identical metallic objects of arbitrary shape, periodically arranged in the $xoy$-plane (Fig. 1). The frequency selective surface has a general skewed lattice defined by primitive vector $a_1$ and $a_2$ and is illuminated by a plane wave impinging with the incidence angle $(\theta_{\text{inc}}, \phi_{\text{inc}})$. Let $S$ designate the surface of the metallic object within the structure’s unit cell. The analysis is based on the solution of the following mixed-potential integral equation (MPIE) [13]: $$-\hat{n} \times E^\text{inc} = \hat{n} \times \left[ -j\omega \vec{G}_A \otimes \vec{J} + \frac{1}{j\omega} (\nabla G_V) \otimes (\nabla' \cdot \vec{J}) \right] \quad (1)$$ which is obtained by enforcing the boundary conditions on the PEC surface $S$. $E^\text{inc}$ is the incident electric field, $\hat{n}$ is the outside unit normal. to $S$, $\vec{J}$ is the unknown current density on $S$, and $\vec{G}_A$ and $G_V$ are the vector and scalar potential GFs that take into account the periodicity of the problem. Equation (1) is solved by applying the MOM in Galerkin form. The unknown current density $\vec{J}$ is expanded using a set of $N$ Rao-Wilton-Glisson (RWG) [6] basis functions and it’s two derivative basis functions (described later) defined on triangular facets $S_k$ of the surface $S$: $$\vec{J} = \sum_{n=1}^{N} I_n f_n$$ (2) where $I_n$ are the unknown coefficients. There are three kinds of basis function used in the paper, that is, RWG basis function, half-RWG basis function and invert-RWG basis function, as shown in Fig. 2. The last two are derived from RWG basis function: $$f_n (\vec{r}) = \begin{cases} (l_n/2A_n^+)\rho_n^+(\vec{r}), & \text{\vec{r} inside } T_n^+ \\ (l_n/2A_n^-)\rho_n^-(\vec{r}), & \text{\vec{r} inside } T_n^- \\ 0, & \text{otherwise} \end{cases}$$ (3) where $l_n$ is the length of the common edge, and $A_n^{\pm}$ is the area of triangle $T_n^{\pm}$. Vector $\rho_n^-$ connects the observation point $\vec{r}$ to the free vertex of the minus triangle. Vector $\rho_n^+$ connects the free vertex of plus triangle to the observation point. There is something worth noting. Figure 2. Three kinds of basis function. (a) RWG basis function. (b) Invert-RWG basis function. (c) Half-RWG basis function. that, for invert-RWG basis functions, the observation point $\vec{r}$ in $T^+_n$ is directed toward the free vertex. The red line stands for the common edge of two triangles. The common edges do not always overlap. As long as the two edges have the same length, and meet a specific physical relationship, then they can build a common edge. This is usually used to deal with the current continuity of the surface meshes at the periodic boundary (PB). 3. 2-D PERIODIC GREEN’S FUNCTION AND ITS EWALD TRANSFORMATION In the spatial domain, the periodic Green’s function $G_p(\vec{r}, \vec{r}_s)$ has the form $$G_p(\vec{r}, \vec{r}_s) = \sum_{m=-\infty}^{\infty} \sum_{n=-\infty}^{\infty} e^{-jk \cdot \vec{\rho}_{mn}} e^{-jk_0 R_{mn}} \frac{4\pi R_{mn}}{A}$$ (4) where $$\vec{\rho}_{mn} = m \cdot a_1 + n \cdot a_2$$ $$R_{mn} = |\vec{r} - \vec{r}_s - \vec{\rho}_{mn}|$$ here $\vec{\rho}_{mn}$ is the translation vector of the lattice. In the spectral domain, $G_p(\vec{r}, \vec{r}_s)$ becomes $$G_p(\vec{r}, \vec{r}_s) = \sum_{m=-\infty}^{\infty} \sum_{n=-\infty}^{\infty} \frac{e^{-jk_{t_{mn}} \cdot (\vec{\rho} - \vec{\rho}_s)}}{2jAk_{z_{mn}}} e^{-jk_{z_{mn}} |z - z_s|}$$ (5) where $A = |a_1 \times a_2|$ is the cross-sectional area of the unit cell, $$\vec{r} = \vec{\rho} + z \cdot \hat{z}.$$ $$\vec{k}_{t_{mn}} = \vec{k}_{t00} + \frac{2\pi}{A} [m(a_2 \times \hat{z}) + n(\hat{z} \times a_1)]$$ is the reciprocal lattice vector. $$k_{z_{mn}} = \sqrt{k_0^2 - \vec{k}_{t_{mn}} \cdot \vec{k}_{t_{mn}},}$$ where $\text{Re}(k_{z_{mn}}) \geq 0$, $\text{Im}(k_{z_{mn}}) \leq 0$. 3.1. Ewald Transformation of PGF The spatial and spectral formulations of PGF are slowly convergent. However, the Ewald method successfully combines both formulations into fast converging series. Here, we present the details of the Ewald transform used to compute the potential GFs of a periodic structure. with general skewed lattice. The Ewald transformation starts from the spatial domain representation of the PGF [Eq. (4)] and makes use of the identity \[ e^{-jkR_{mn}} = \frac{2}{\sqrt{\pi}} \int_{0}^{\infty} e^{-R_{mn}^2 s^2 + \frac{k_0^2}{4s^2}} ds \] where \( s \) is a complex variable. In order that the integrand converges as \( s \to 0 \) for a wavenumber \( k_0 \) with an arbitrary amount of loss, the path is chosen so that \( \arg(s) = \pi/4 \) as \( s \to 0 \). In order to have convergence as \( s \to \infty \), the path is chosen so that \( -\pi/4 \leq \arg(s) \leq \pi/4 \). Next, (6) is substituted into (4) and the integral is split into two terms, as \[ G_p(r, r') = G_{p1}(r, r') + G_{p2}(r, r') \] where \[ G_{p1}(r, r') = \int_{-\infty}^{\infty} \sum_{m=-\infty}^{\infty} \sum_{n=-\infty}^{\infty} e^{-jk_{100} \cdot \rho_{mn}} \times \frac{2}{\sqrt{\pi}} \int_{0}^{E} e^{-R_{mn}^2 s^2 + \frac{k_0^2}{4s^2}} ds \] \[ G_{p2}(r, r') = \int_{-\infty}^{\infty} \sum_{m=-\infty}^{\infty} \sum_{n=-\infty}^{\infty} e^{-jk_{100} \cdot \rho_{mn}} \times \frac{2}{\sqrt{\pi}} \int_{E}^{\infty} e^{-R_{mn}^2 s^2 + \frac{k_0^2}{4s^2}} ds \] Using the identity [16, Eq. (7.7.7)] \[ \frac{2}{\sqrt{\pi}} \int_{E}^{\infty} e^{-R_{mn}^2 s^2 + \frac{k_0^2}{4s^2}} ds = \frac{1}{2R_{mn}} \left[ e^{-jk_{00}R_{mn}} \text{erfc} \left( R_{mn}E - \frac{jk}{2E} \right) + e^{jk_{00}R_{mn}} \text{erfc} \left( R_{mn}E + \frac{jk}{2E} \right) \right] \] where erfc is the complementary error function, \( G_{p2}(r, r') \) can be written as \[ G_{p2}(r, r') = \sum_{m=-\infty}^{\infty} \sum_{n=-\infty}^{\infty} \frac{e^{-jk_{100}R_{mn}}}{4\pi R_{mn}} \times \text{real} \left[ e^{jk_{00}R_{mn}} \text{erfc} \left( R_{mn}E + \frac{jk}{2E} \right) \right] \] which is essentially a “modified” spatial-domain part of the PGF. Making use of the Poisson transformation [17, 18], Eq. (8) is finally transformed as \[ G_{p1}(r, r') = \sum_{m=-\infty}^{\infty} \sum_{n=-\infty}^{\infty} \frac{e^{-jk_{mn}(\rho - \rho')}}{4Ak_{zmnmn}} \times \left[ e^{-jk_{mn}(z - z')} \text{erfc} \left( \frac{jk_{zn}}{2E} - (z - z') E \right) + e^{jk_{mn}(z - z')} \text{erfc} \left( \frac{jk_{zn}}{2E} + (z - z') E \right) \right] \] 3.2. Optimum Splitting Parameter $E$ By analysis of the asymptotic behavior of the series terms, the approximation to the optimal value for 2-D general skewed lattices is given by [13, 19]: $$E = \max \left( \sqrt{\frac{\pi}{A}}, \frac{k}{2H} \right)$$ \hspace{1cm} (13) where $H^2$ is the maximum exponent permitted. For example, consider a worst case in which there is no phasing ($k_x0 = k_y0 = 0$). If we require $H^2 = 9$ we need $E > k/2H \approx k/6 \approx 1/\lambda$. In other words, for $H^2 = 9$, the choice of the optimum parameter $E = \sqrt{\pi/A}$ is a good choice if $A < 3\lambda^2$. Choosing this value and adjusting the summation limits so that the most dominant terms are kept, in almost all practical cases it is sufficient to include only nine summation terms in (11) and (12) (i.e., the summation limits are from $-1$ to $+1$), in which the error level is usually less than 0.1%. 3.3. Extraction of the Singular Term of PGF By extracting its singularity [20], the periodic Green’s function (PGF) can be expressed as $G_p = G_{p1} + \left[ G_{p2} - 1/(4\pi R) \right] + 1/4\pi R$. The singularity subtraction technique [21] used in this paper can compute the singularity of $|r - r'|^n (n \geq -3)$ type. The remaining part using L’Hospital rule has a finite value at $R \to 0$ since: $$\lim_{R \to 0} \left\{ \frac{1}{8\pi R} \sum_{\pm} e^{\pm jkR} \text{erfc} \left( RE \pm \frac{jk}{2E} \right) - \frac{1}{4\pi R} \right\} \hspace{1cm} (14)$$ where the real part of $\text{erfc} (jk/2E)$ equates to 1. 4. INTERPOLATION OF PGFS In the following, the interpolation procedure of PGFs is introduced. PGF values are pre-computed at each frequency point and tabulated in a rectangular 3-D grid along $x-x'$, $y-y'$, and $z-z'$. The GF values needed to compute the numerical integrals in the MoM matrix are then retrieved from the table using interpolation routines (quadrature interpolation). This is computationally very advantageous. The reason is in the fact that interpolating the GF values from the table is much faster than computing the Ewald sums directly (since this has to be done for every pair of source and field triangles in the numerical integration using cubature formulas.) The relative error \( \varepsilon \) obtained by interpolating the PGFs is defined as \[ \varepsilon = \left| \frac{G^{\text{int}} - G^{\text{ex}}}{G^{\text{ex}}} \right| \] where \( G^{\text{int}} \) and \( G^{\text{ex}} \) are the interpolated and the exact data, respectively. The exact data are obtained by calculating the series (11) and (12) with an accuracy \( \varepsilon = 10^{-7} \); the relative errors less than \( \varepsilon = 10^{-7} \) have therefore been neglected. We take the 2-D metallic structure with orthogonal lattices shown in Fig. 3 (a) as example. The threshold of far interaction between field and source triangles usually is set to \( \lambda/10 \). When \( |r - r'| < \lambda/10 \), PGF change dramatically and it’s singularity must be extracted. For the near interaction, the 2-D grid is in \(-0.1\lambda < \Delta x < 0.1\lambda, -0.1\lambda < \Delta y < 0.1\lambda, z - z' = 0\); For far interaction, the 2-D grid is in \(-|a_1| < \Delta x < |a_1|, -|a_2| < \Delta y < |a_2|, z - z' = 0\), shown in Fig. 3(b). The red line stands for the singular boundary, so the PGFs at the center of sub-grid generally are pre-computed and stored. In Fig. 4, an example is shown of the relative error in the interpolation of PGF involved far and near interaction through quadrature interpolation, with various values of \( N^{\text{int}} \). An extensive number of comparisons have also been performed to estimate the accuracy reached with different numbers of interpolation points. In Fig. 5, signs (A...L) are the sampling points for interpolation. A very high level of accuracy is anyway easily obtained with a relatively small number of interpolation points. The side length range of the sub-grid usually is \( 0.015 \sim 0.03\lambda \), and the higher interpolation accuracy \( \varepsilon < 10^{-3}, \text{even } 10^{-5} \) can be obtained. \[\text{Figure 3.}\] The PGFs at the center of sub-grids (yellow point) will be pre-computed and stored: (a) The unit cell of FSS. (b) A rectangular 2-D grid with \( N^{\text{int}} \times N^{\text{int}} \) sub-grids. Figure 4. The relative error of a single point. Reference structure: primitive vector $a_1 = a_2 = 0.55\lambda$; phase shifts $k_{x0} = \sqrt{6}k_0/4$, $k_{y0} = \sqrt{2}k_0/4$. Accuracy reached interpolating PGFs through quadratic interpolation, with a 2-D grid of $N_{\text{int}} \times N_{\text{int}}$ equispaced points in $-0.55\lambda < \Delta x < 0.55\lambda$, $-0.55\lambda < \Delta y < 0.55\lambda$, $z - z' = 0$. (a) Far-interaction $r - r' = (/-0.21\lambda, 0.29\lambda, 0/)$. (b) Near-interaction $r - r' = (/-0.011\lambda, 0.018\lambda, 0/)$. Figure 5. The relative error of a series of points. Reference structure: primitive vector $a_1 = a_2 = 0.45\lambda$; phase shifts $k_{x0} = k_0/4$, $k_{y0} = \sqrt{3}k_0/4$. Accuracy reached interpolating PGFs through quadratic interpolation, with a 2-D grid of $N_{\text{int}} \times N_{\text{int}}$ equispaced points in $-0.45\lambda < \Delta x < 0.45\lambda$, $-0.45\lambda < \Delta y < 0.45\lambda$. The data plotted refer to the circular line $(x - x')^2 + (y - y')^2 = (0.23\lambda)^2$, $z - z' = 0$; The number of sampling point is 12, the first one (Point A) starts from $\varphi = 15^\circ$. For the case of FSS under the normal incidence of plane wave, because the phase shift factor is zero, PGF value is just related to $|r - r'|$. For the near interaction, the 2-D grid is in $0 < \Delta x < 0.1\lambda$, $0 < \Delta y < 0.1\lambda$, $z - z' = 0$; For far interaction, the 2-D grid is in $0 < \Delta x < |a_1|$, $0 < \Delta y < |a_2|$, $z - z' = 0$. The number of pre-computed PGFs can be reduced to 1/4 of the original one. 5. FSS UNIT CONNECTING TO PERIODIC BOUNDARY (PB) This case usually appears in aperture periodic structure shown in Fig. 6. The triangle meshes connecting to the periodic boundary (PB) requires special handling. A possible imposition of periodic boundary condition (PBC) to the surface mesh has been discussed in detail in [22]. The basic observation is that the fields on the PB of a surface mesh are related to the fields on the opposite PB through a phase relation. If the unknown field at an edge on one of the PBs is $e_m$, the value $e_n$ of the field at the corresponding edge on the opposition PB is given by $$e_n = e_m \cdot e^{-j\vec{k}_{tot} \cdot \Delta \vec{r}}$$ where $\Delta \vec{r} = (a_1$ or $a_2)$ is the vector joining the two edges. The two triangles (red line) at the left and right PB respectively constitute a RWG edge. Similarly, the two triangles (green line) at the up and low PB respectively constitute a RWG edge. This relation requires that the surface meshes of the opposite PBs be identical. Figure 6. The triangle mesh connecting to PB. 6. USING LATTICE SYMMETRY TO SIMPLIFY THE GEOMETRY MODEL Here we take the aperture periodic structure shown in Fig. 7 for example, because the aperture structure is relatively complex. The triangle meshes connecting to the periodic boundary (PB) require special handling. 6.1. Regular Array Under Normal Incident of Plane Wave Suppose FSS is under the normal incidence of plane wave with the \(E\)-field parallel to the \(x\)-axis (\(TEM_x\)). The geometry model was simplified to 1/4 of original one using the lattice symmetry (Fig. 8). The time of filling MOM matrix and solving linear system by iterative method is reduced approximately to 1/4 of original one. In addition to the primary source triangle, the coordinates of other three source triangles can be obtained through mirror. The relationship for the current expansion coefficients of the four source triangles is as follows: \[ I_1 = -I_2 = -I_3 = I_4 \] ![Figure 7. Unit cell of rectangular aperture FSS (blue line: PB).](image) ![Figure 8. The field and source triangles. Red arrows are the current direction of the four source triangles.](image) The impedance matrix of the mixed-potential integral equation (MPIE) is given by $$Z_{mn} = \sum_{k=1}^{4} c(k) \cdot \left\{ j\omega \langle f_m, \vec{G}_A \otimes f_{nk} \rangle + \frac{1}{j\omega} \langle \nabla \cdot f_m, G_V \otimes (\nabla' \cdot f_{nk}) \rangle \right\}$$ where $$c(k) = \begin{cases} 1, & \text{if } k = 1 \text{ or } 4 \\ -1, & \text{if } k = 2 \text{ or } 3 \end{cases}$$ That is, one field triangle corresponds to four source triangles. $f_{n1}$ is the basis function of primary source triangle $n_1$; $f_{n2}$, $f_{n3}$ and $f_{n4}$ are the basis function of the other three source triangles ($n_2$, $n_3$, $n_4$), respectively. The triangle meshes connecting to left and right edges (red line) should be assigned half-RWG basis function, because there is a current flowing through left and right edges. There is no current following through upper and lower edges, so the two edges can be considered as the open boundary edges. 6.2. Regular Array Under Oblique Incident of Plane Wave Suppose FSS is under the oblique incidence of plane wave ($xoz$-plane is the incident plane) with $V$-polarization and $H$-polarization respectively. $V$-polarization denotes the $E$-field parallel to the incident plane; $H$-polarization denotes the $E$-field perpendicular to the incident plane. The geometry model was simplified to 1/2 of the original one using the lattice symmetry (Fig. 9). The time of filling MOM matrix and solving linear system by iterative method is reduced approximately to 1/2 of the original one. The relationship between current expansion coefficients of two source triangles is as follows: \[ I_1 = \begin{cases} I_2, & \text{if } V\text{-Polarization} \\ -I_2, & \text{if } H\text{-Polarization} \end{cases} \] The impedance matrix of the mixed-potential integral equation (MPIE) is given by **V-Polarization:** \[ Z_{mn} = \sum_{k=1}^{2} j\omega \left\langle f_m, \mathcal{G}_A \otimes f_{nk} \right\rangle + \frac{1}{j\omega} \left\langle \nabla \cdot f_m, G_V \otimes (\nabla' \cdot f_{nk}) \right\rangle \] **H-Polarization:** \[ Z_{mn} = \sum_{k=1}^{2} c(k) \cdot \left\{ j\omega \left\langle f_m, \mathcal{G}_A \otimes f_{nk} \right\rangle + \frac{1}{j\omega} \left\langle \nabla \cdot f_m, G_V \otimes (\nabla' \cdot f_{nk}) \right\rangle \right\} \] where \[ c(k) = \begin{cases} 1, & \text{if } k = 1 \\ -1, & \text{if } k = 2 \end{cases} \] The triangle meshes connecting to left and right edges (red line) should be assigned RWG basis function. In the case of V-polarization, there is no current following through upper and lower edges, so the two edges can be considered as the open boundary edges. In the case of H-polarization, the triangle meshes at the upper and lower edges should be assigned half-RWG basis function, due to the existing current following through the two edges. ### 6.3. Skewed Array under Normal Incident of Plane Wave Supposed FSS is under the normal incidence of plane wave with the E-field parallel to the x-axis (TEM\_x). The geometry model was simplified to 1/2 of original one using the lattice symmetry (Fig. 10). **Figure 10.** The field and source triangles. Red arrows are the current direction of the two source triangles. **Figure 11.** Invert-RWG consisting of two corresponding triangles. The time of filling MOM matrix and solving linear system by iterative method is reduced approximately to $1/2$ of original one. The relationship between current expansion coefficients of two source triangles is as follow $$I_1 = -I_2$$ The impedance matrix of the mixed-potential integral equation (MPIE) is given by $$Z_{mn} = \sum_{k=1}^{2} c(k) \cdot \left\{ j\omega \left\langle f_m, \bar{G}_A \otimes f_{nk} \right\rangle + \frac{1}{j\omega} \left\langle \nabla \cdot f_m, G_V \otimes (\nabla' \cdot f_{nk}) \right\rangle \right\}$$ where $$c(k) = \begin{cases} 1, & \text{if } k = 1 \\ -1, & \text{if } k = 2 \end{cases}$$ In this case, there are currents following through the three patch edges. Take the third edge of the patch (Boundary 3) for example, as shown in Fig. 11. Two triangles connected by the blue line constitute an invert-RWG basis function. The third edge of the patch has 4 invert-RWGs. Two interior edges of the invert-RWG are symmetrical about the center of patch edge (red dot). The triangles at the first and second edge of the patch constitute the invert-RWG in the same way, which have 7 and 5 invert-RWGs respectively. If the number of triangles at the patch edge is odd, the triangle at the center of the patch edge should be assigned half-RWG. 7. NUMERICAL EXAMPLES 7.1. Jerusalem Cross In the first example, we consider the problem of a free-standing planar array of perfectly conducting Jerusalem-Cross shaped patch shown in Fig. 12. Fig. 13 shows the reflection coefficient for the Floquet TEM mode with the electric field oriented in the $x$-direction ($TEM_x$). The number of terms in both Ewald sums is set to 9. Further increasing the number of terms does not show any changes in the reflection coefficient. The one-4th model is discretized into 80 triangles in the whole frequency band. We compare the results obtained using our approach (black solid line) with the results obtained using the spectral-domain approach [1] (Blue ring) and the numerical values taken from [13] (red solid line). Good agreement with the reference results can be observed in the reflection coefficient. Figure 12. The unit model of Jerusalem cross array is simplified to one-4th model. Dimension are in millimeters: \( w = 1.9, \ l_1 = 3.8, \ l_2 = 5.7, \ a_1 = a_2 = 15.2 \). Figure 13. (a) Magnitude. (b) Phase of the reflection coefficient. 7.2. Double Square-loop This example involves a double-square-loop periodic structure defined on a 9.5588 mm square grid. The dimensions of the element are shown in Fig. 14. The incident field has center frequency \( f_c = 14.5 \text{ GHz} \), bandwidth \( f_{bw} = 7 \text{ GHz} \), and illuminates the screen from the \((\theta_{inc} = 30^\circ, \ \phi_{inc} = 0^\circ)\) direction with V-polarization and the \((\theta_{inc} = 45^\circ, \ \phi_{inc} = 0^\circ)\) direction with H-polarization, respectively. Fig. 15 shows the reflection and transmission coefficients of the structure. Black solid line and blue solid line represent the reflection and transmission coefficients obtained using our technique, respectively; Red-ring and green dashed lines represent the results using the simulation technique. Figure 14. The unit model of double square-loop array is simplified to one-2nd model. Dimension are in millimeters: $w_1 = w_g = 0.5588$, $w_2 = 1.125$, $l = 6.4588$, $a_1 = a_2 = 9.5588$. Figure 15. Reflection and transmission coefficient. (a) Incident direction ($\theta_{\text{inc}} = 30^\circ$, $\phi_{\text{inc}} = 0^\circ$) with $V$-polarization. (b) Incident direction ($\theta_{\text{inc}} = 45^\circ$, $\phi_{\text{inc}} = 0^\circ$) with $H$-polarization. of EMSS FEKO. Very good agreement with the reference results of FEKO can be observed. Here, the one-2nd model is discretized into 100 triangles, and the number of terms in both Ewald sums is set to 9. 7.3. Conducting Screen Perforated with Circular Holes The transmission of a plane wave incident on a thin perfectly conducting screen perforated periodically with circular holes is considered. The geometry of the problem is defined in the inset of Fig. 17 that shows the geometry layout of the 2-D array of circular holes in thin conducting screen. The dimensions of the element are shown in Fig. 16. The reflection and transmission coefficients for a plane wave Figure 16. The unit model of circular aperture array is simplified to one-2nd model. Dimension are in millimeters: \( D = 12, a_1 = a_2 = 10\sqrt{3} \) and \( \alpha = 60^\circ \). Figure 17. Transmission coefficient. with the \( E \)-field parallel to the \( y \)-axis at normal incidence are plotted as the function of frequency in Fig. 17. The results obtained using the presented method (black solid lines) are compared to the simulations (red dot lines) and measured values (blue ring) taken from [23]. A very good agreement with the measured values [23] can be noticed. Here, only nine terms in both Ewald sums give the convergent results for a mesh density of one-2nd model with 108 triangular cells. 7.4. Cross-Shaped Quasi-Optical Filter Finally, we analyze the bandpass filter formed by periodic cross-shaped holes with a resonance frequency of 280 GHz shown in Fig. 18 [24]. The one-4th model is discretized into 218 triangles to ensure accurate results obtained in the entire frequency band. The transmission coefficients for a plane wave with the \( E \)-field parallel to the \( x \)-axis at normal incidence (TEM$_x$ mode) are plotted as a function of frequency in Fig. 19. Black solid lines represent the results obtained using our technique, red solid lines represent the results using the simulation technique of [24], and the measured values are denoted via ring (o). Very good agreement with the reference results can be observed. Since simulation relative bandwidth is very wide and the value of the splitting parameter may be unbalanced, we need more terms in the spectral sum (49) than in the spatial one (9) to ensure the GF convergence [13]. The time needed to solve this structure is 6.3 s per frequency point on a PC with Intel core i5 2.8-GHz processor, 4 GB of RAM, and Microsoft Win7 operating system. The corresponding CPU time on the same PC is 122 s and 896 s per frequency point for Ansoft Designer and EMSS FEKO, respectively. **Figure 18.** The unit model of cross-shaped aperture array is simplified to one-4th model. Dimension are in micrometers: Square lattice period $a_1 = a_2 = 810$, slot length $l = 570$, slot width $w = 160$. **Figure 19.** (a) Magnitude. (b) Phase of the transmission coefficient. 8. CONCLUSION We propose a spatial-domain integral-equation method for the analysis of frequency selective surfaces (FSS) using Ewald transformation and lattice symmetry. The method uses Ewald’s acceleration technique to speed up the convergence of the GFs. Moreover, we use the lattice symmetry to simplify the unit model and the unknowns are reduced greatly, so that the solving time of MoM linear system and the matrix-filling time are reduced dramatically. Two new basis functions deriving from RWG basis function are introduced to deal with the current condition of the unit patch. A number of periodic structures with general skewed lattices under oblique and normal incidence plane-wave excitations are studied. The simulations show that, in most cases, only nine terms in both Ewald sums suffice to obtain results that agree very well with the measured or numerical results reported in the literatures. Therefore, it shows that our technique is an accurate and efficient method for analyzing periodic structures. Extension of the proposed approach to the analysis of arbitrary complicated periodic structures by using volume-surface integral equation (VSIE) [25–27] and adaptive cross approximation (ACA) [28] is feasible and under development. ACKNOWLEDGMENT This work is funded by the National Natural Science Foundation of China under Grant 60871003 and 60801008. REFERENCES
Dopamine Modulates Motor Control in a Specific Plane Related to Support Marc Herbin, Caroline Simonis, Lionel Reveret, Rémi Hackert, Paul-Antoine Libourel, Daniel Eugène, Jorge Diaz, Catherine S de Waele, Pierre-Paul Vidal To cite this version: HAL Id: mnhn-02170782 https://mnhn.hal.science/mnhn-02170782 Submitted on 2 Jul 2019 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. RESEARCH ARTICLE Dopamine Modulates Motor Control in a Specific Plane Related to Support Marc Herbin1,*, Caroline Simonis1,2, Lionel Revéret3, Rémi Hackert1, Paul-Antoine Libourel1,4, Daniel Eugène5, Jorge Diaz6, Catherine de Waele7, Pierre-Paul Vidal7 1 UMR 7179 MNHN/CNRS, Museum National d'Histoire Naturelle, Dpt EGB, CP 55, 57 rue Cuvier 75231 Paris cedex 05, France, 2 MENESR, DEPP, 61–65 rue Dudot 75015 Paris, France, 3 LJJK, CNRS UMR 5224 INRIA/LJF, INRIA Rhône-Alpes, 655 av de l'Europe, 38330 Montbonnot, France, 4 SLEEP Physiopathologie des réseaux neuronaux du cycle sommeil, Centre de Recherche en Neurosciences de Lyon, INSERM U1028—CNRS UMR5292, Faculté de Médecine Laennec, 7 rue Guillaume Paradin, 69372 LYON Cedex 08 France, 5 Centre de Neurophysique, Physiologie, Pathologie, Université Paris Descartes-CNRS UMR-8119, 45 rue des Saint-Pères, 75270 Paris cedex 06, France, 6 Centre de Psychiatrie et Neurosciences, INSERM UMR 894—Université Paris Descartes, 2ter, rue d'Alésia, 78014 Paris, France, 7 COGNAC-G Université Paris Descartes-CNRS UMR-MD-SSA, 45 rue des Saint-Pères, 75270 Paris cedex 06, France * herbin@mnhn.fr Abstract At the acute stage following unilateral labyrinthectomy (UL), rats, mice or guinea pigs exhibit a complex motor syndrome combining circling (HSCC lesion) and rolling (utricular lesion). At the chronic stage, they only display circling, because proprioceptive information related to the plane of support substitutes the missing utricular information to control posture in the frontal plane. Circling is also observed following unilateral lesion of the mesencephalic dopaminergic neurons by 6-hydroxydopamine hydrobromide (6-OHDA rats) and systemic injection of apomorphine (APO rats). The resemblance of behavior induced by unilateral vestibular and dopaminergic lesions at the chronic stage can be interpreted in two ways. One hypothesis is that the dopaminergic system exerts three-dimensional control over motricity, as the vestibular system does. If this hypothesis is correct, then a unilateral lesion of the nigro-striatal pathway should induce three-dimensional motor deficits, i.e., circling and at least some sort of barrel rolling at the acute stage of the lesion. Then, compensation could also take place very rapidly based on proprioception, which would explain the prevalence of circling. In addition, barrel rolling should reappear when the rodent is placed in water, as it occurs in UL vertebrates. Alternatively, the dopaminergic network, together with neurons processing the horizontal canal information, could control the homeostasis of posture and locomotion specifically in one and only one plane of space, i.e. the plane related to the basis of support. In that case, barrel rolling should never occur, whether at the acute or chronic stage on firm ground or in water. Moreover, circling should have the same characteristics following both types of lesions. Clearly, 6-OHDA and APO-rats never exhibited barrel rolling at the acute stage. They circled at the acute stage of the lesion and continued to do so three weeks later, including in water. In contrast, UL-rats, exhibited both circling and barrel rolling at the acute stage, and then only circled on the ground. Furthermore, barrel rolling instantaneously reappeared in water in UL rats, which was not the case in 6-OHDA and APO-rats. That is, the lesion of the dopaminergic system on one side did not compromise trim in the pitch and roll planes, even when proprioceptive information related to the basis of support was lacking as in water. Altogether, these results strongly suggest that dopamine does not exert three-dimensional control of the motor system but regulates postural control in one particular plane of space, the one related to the basis of support. In contrast, as previously shown, the vestibular system exerts three-dimensional control on posture. That is, we show here for the first time a relationship between a given neuromodulator and the spatial organization of motor control. Introduction The vestibular system exerts a tridimensional control on posture and movement [1,2]: the horizontal canal information (HSCC) stabilizes the head-neck ensemble in a plane parallel to the plane of sustentation, including the detection of the straight-ahead direction. The utricular information stabilizes the orientation of the head-neck ensemble in the frontal and sagittal plane including the detection of the gravitational vertical. Accordingly, when all vestibular sensors are lesioned on one side (UL rat), the postural syndrome observed, on ground at the acute stage, combines two types of deficits: a- a rotation of the head about the cervical column axis and circling (HSCC lesion); b- a lateral tilt of the head-neck ensemble about the thoracic column axis and rolling (utricular lesion). Later on, UL rats, mice or guinea pigs only display circling, presumably because proprioceptive information related to the plane of support substitutes for the missing utricular information to control posture in the frontal plane. However, as soon as UL rats, mice or guinea pigs are placed in a tank of water, a violent barrel rolling reappears due to the disappearance of the proprioceptive information i.e. the three-dimensional nature of the vestibular deficit reappears (P.-P. Vidal and others, personal observation). Interestingly, unilateral dopaminergic lesion also induces a rotation of the head about the axis of the cervical column towards the lesion side and a circling behavior [3–7]. As early as 1968, it was shown in a seminal paper by Ungerstedt [8] that unilateral degeneration of the whole nigro-neostriatal dopamine (DA) neuron system in rats, after intracerebral injection of 6-hydroxy-DA (6-OHDA) into the substantia nigra, produced marked motor asymmetries with turning toward the side ipsilateral to the lesion. Furthermore, a single unilateral injection of DA or unilateral application of DA crystals into the NCP, which is richly innervated by DA nerve terminals was found to produce an asymmetric posture and turning contralateral to the side of application by the same author [9, 10]. These papers showed for the first time that the nigro-neostriatal DA neurons were of considerable importance for posture and generalized motor function. The resemblance between the consequences of a unilateral vestibular and dopaminergic lesion on motor behavior can be interpreted in two ways. One hypothesis is that the dopaminergic system exerts three-dimensional control over motricity, as the vestibular system does. If this hypothesis is correct, then a unilateral lesion of the nigro-striatal pathway should induce three-dimensional motor deficits, i.e., circling and at least some sort of barrel rolling at the acute stage of the lesion. Then, compensation of the postural syndrome in the frontal plane could also take place very rapidly, as in UL rats due to limbs proprioceptive information related to ground support, which would explain the prevalence of circling. In addition, barrel rolling should reappear when the rodents with unilateral dopaminergic lesions are placed in water due to the disappearance of proprioception. Alternatively, the dopaminergic network, together with neurons processing the horizontal canal information, could control the homeostasis of posture and locomotion specifically in one and only one plane of space, i.e. the plane related to the basis of support. In that case, barrel rolling should never occur, whether at the acute or chronic stage on firm ground or in water. Moreover, circling should have the same characteristics following both types of lesions. This paper is an attempt to address these questions by comparing quantitatively in three dimensions, the motor behavior of rats following unilateral vestibular and dopaminergic lesions both on the ground and in water. **Materials and Methods** **Animals** The animals used in this study were 8-week-old male Wistar rats (Elevage Janvier, France). They were housed in groups of three per cage in a room with constant temperature (22°C), under 12:12 light-dark cycle, and with food pellets and water *ad libitum*. Data were collected from four wild type rats used as controls, eight rats with (left or right) unilateral lesions in the Substantia Nigra pars compacta, and five hemi-labyrinthectomized rats (left side). **Surgeries** All surgeries were performed in deeply anesthetized rats (halothane). All studies were carried out in accordance with European Community Council directive of November 24th, 1986, and following the procedures issued by French Ministère de l’Agriculture. All efforts were made to minimize animal suffering and to reduce the number of animals used. All experiments were performed in Animal Research Facility under the approval ID B-75-1015 delivered by "Direction des Services Vétérinaires de la Préfecture de Paris" (France) and approved by a review board of Université Paris Descartes. **6-OHDA lesion.** Thirty minutes prior to surgery, the rats received an injection of desmethylimipramine (15 mg/kg ip) to protect noradrenergic neurons from the neurotoxic effects of 6-hydroxydopamine hydrobromide (6-OHDA; Sigma Chemical Co.). Under sodium pentobarbital (Somnotol) anesthesia (25 mg/kg), they were positioned in a Kopf stereotoxic instrument and received an infusion of 6-OHDA (8 ti% in 4 <J of 0.9% saline and 0.1% ascorbic acid) at a rate of 1 iA/mm through a 26-ga. stainless steel cannula (outer diameter, 0.045 cm). The cannula was left in place for a further 3 min to allow for passive diffusion away from the tip. Doses of 6-OHDA are expressed as the weight of the base. The cannula was aimed at the left A9 region of the substantia nigra (SN) for half of the rats and at the right A9 region for the other half. The coordinates were A 4.4, L 0.9, and V 7.2 for rats weighing 150–200 g and A 4.8, L 1.5, and V 7.5 for rats weighing 200–250 g [11]. The lesion sites were verified at the end of the study using serial coronal sections of the brain stained with cresyl violet. In a second time, a quantification of TH immunostained neurons was done in SN on both sides to verify that the number of stained neurons was lower in the injected side than the other side (Fig 1). Apomorphine hydrochloride was dissolved in a solution of 0.9% saline and 0.1% ascorbic acid and was injected sub-cutaneously under the nape of the neck. In each case, the injection volume was 1 ml/kg; solutions of drugs were prepared fresh daily. Out of a total of 8 lesioned rats in the substantia nigra, only 3 were selected for the analyses after histological verification. **Labyrinthectomy.** In brief, a global inner ear lesion was performed with the aid of an operating microscope. A retroauricular approach was used. The entire length of the ventral edge of the meatus was destroyed and the facial nerve sectioned. The tympanic membrane, malleus and incus were removed to expose the pterygopalatine artery caudal to the stapes. This artery was coagulated using an electro-coagulator, the stapes removed and the oval window opened. Finally, the vestibule was destroyed using a suction tube. A post-operative i.m. Terramycin (Pfizer, Paris, France) injection was given (50 mg tetracycline) to prevent infection, and the animals were then left free in normal visual conditions until compensation of the vestibular deficits [12]. Out of a total of 5 rats labyrinthectomized, 3 were tested in this study. Locomotor behavior To follow the movement in three-dimensional space, five digital cameras were used to register sequences of 8 seconds at 200 frames per second. Each of them was placed in specific planes of space so that at least two cameras would be able to capture and follow the same point in movement simultaneously. The frequency was selected as a compromise between maximum time resolution and the spatial definition required for a frame-by-frame data analysis. The referenced animal was then first set on a small wood platform 30 x 30 cm, and filmed with three cameras (Prosilica GE680) at 200 frames/second (Fig 2A). This first step was done to follow the locomotor behavior on the ground. Secondly, each animal was put in a transparent glass pool (80 x 40 x 40 cm) filled with 32 C° water to a height of 25 cm (Fig 2A). The rats were delicately positioned at the surface of the water in the center of the tank and filmed at 200 frames/sec with the all five video cameras (3 Prosilica GE680, 1 Basler, 1 SVSi Memview). Each exercise was done before and after (two minutes after) subcutaneous injection of Apomorphine (APO). To follow the changes of the skeletal geometry of the individual in the different conditions, fifteen small colored spherical markers (diameter of 5mm) were stuck on the skin of each animal (Fig 2B and 2C; S1 Movie); 3 on the head (1 between eyes on nasal, 2 close to each ear) to obtain a three- dimensional reference point, 4 on the back (the first between scapulae, and the last one close to the first pelvic vertebrae and 2 evenly spaced between these two markers, to characterize the spine axis), 1 on each shoulder and at the level of each femoro-pelvic junction to complete position of spine, and finally 1 on each foot, to identify the foot movement. The average velocity of body rotation was determined for each episode and the mean value was then calculated. Quantitative data acquisition was performed off-line using custom software (Loco 3.01), and it was used for the 2D tracking of markers in every camera view. Using geometrical camera calibration from an object with known dimension and standard stereoscopic triangulation, the software allows the determination of the 3D Cartesian coordinates of the tracked markers along a sequence. These 3D trajectories were used to calculate various angles describing the skeletal geometry of the animal during locomotor behaviors (circling and pivoting). In addition, 3D anatomical models of the head and skeleton have been aligned with respect to the 3D trajectories of markers. These 3D anatomical models have been collected using an accurate microCT X-ray scanner (50 microns accuracy). This anatomical model permitted identification of the position of the different anatomical markers fixed on the skin of the animal (Fig 2C). The 3D anatomical models include a segmentation of the vestibular system, allowing an estimation of the trajectory of the pitch angle of the HSCC (Fig 2D, 2E and 2F). Four WT rats have been scanned. Vestibular systems have been identified, including HSCC. Anatomical locations of head markers have been identified also on the 3D head models. It allowed us to estimate a pitch angle between the plane including the three head markers and the HSCC of 28°±6° (p < 0.01). The head markers allowed us to calculate the pitch, the yaw and the roll of the head. To estimate the pitch angle (PitchH), we calculated the mean angle from the difference of pitch angle between the Marker 1 and 2 and pitch angle of the Marker 1 and 3 (relative to horizontal). The roll angle (RollH) was calculated between Marker 2 and 3. Fig 2. Methods used to measure locomotor behavior and to model the 3D trajectories of the different part of the skeleton. (A) Setup used on overground; 3 cameras permit motion capture of the rat on the ground. (B) Setup used to capture motion of the rat in the water; 2 cameras capture the movement of the rat over the water, and 3 cameras capture the movement underwater. (C) Position of the different markers on the skin of the rat. Green for the head, white for the vertebral column, red for the girdles and blue for the distal part of the limbs. (D) The cutaneous markers and their relative positions on the skull. (E) Head of the rat and the different angles analyzed (3D angle, PitchH, YawH and RollH). (F) Occipital view of the head and localization of the three semicircular canals. (G) Focus on the vestibular region. (relative to horizontal), and lastly the yaw angle (YawH) between segment delimited by Marker 1 and the theoretical midpoint between Marker 2–3 and the segment delimited by this same midpoint marker and the marker stuck between scapulas. Supplemental angles were measured along the spine axis, the yaw angle between the cervical and thoracic column (YawC1) and the yaw angle between the thoracic and lumbar column (YawC2). A cumulative value from the two previous yaw gave the yaw of the column (YawC = global curvature of the column). The roll angle (tilt) at the shoulder girdle level and the roll angle (tilt) at the pelvic girdle level were also quantified. Statistical comparisons were conducted using one-way ANOVA, and groups were then compared by means of the Bonferroni’s post-hoc test. The vectors, the angles analyzed and the statistics were computed using R [13], Statistica 6.1 (StatSoft, Inc.), and Prism3.02 (GraphPad Software, Inc). Results Motor behavior Overground The control animals (WT) placed on the platform walked along the edges and tried to get out (a theoretical diameter of 38 cm corresponding to the size of the platform was done for reference Table 1), then neither description of the locomotion, nor measures on the trajectories of the individual were done in these situations. However the YawH and RollH were estimated from straight ahead locomotion on a horizontal surface (YawH = 180°, RollH = 0°) (Table 2), while the PitchH (28°±6) could be measured from video-radiographies of previous studies on WT rat in movements. Following unilateral destruction of the dopaminergic neurons, the 6-OHDA-rats placed on the platform exhibited a circling behavior ipsiversive to the lesion (Fig 3A). The hindlimb ipsilateral to the lesion was never fully lifted off, but several repositionings at the center of the circular trajectory occurred (Fig 4A). The others limbs showed alternating movements, with footfalls inside the trajectory of the head. The equivalent diameters of the circles were smaller than the diameter of the platform, and the rotation speed was 9 cm/s (Table 1). The position of the head was slightly different of the WT, the head being in a more horizontal position, the PitchH was less pronounced, the YawH was oriented toward the sense of the rotation, as the tilt (RollH) of the head (Table 2). The vertebral column was more curved than WT (YawC = 57°±1), with a difference of the YawC2, while the YawC1 did not change (Table 2). Table 1. Characteristics of the trajectory overground and in water for each rat conditions. <table> <thead> <tr> <th></th> <th>Diameter of the circling Behavior (cm)</th> <th>Number circle/mn</th> <th>Rotation speed (cm/s)</th> </tr> </thead> <tbody> <tr> <td></td> <td>WT</td> <td></td> <td></td> </tr> <tr> <td></td> <td>G</td> <td>38 * APO (38 for Plateform)</td> <td>NR</td> </tr> <tr> <td></td> <td>W</td> <td>76 ± OH,APO (76 for pool)</td> <td>5 ± 3 * APO,UL</td> </tr> <tr> <td></td> <td>6 OHDA</td> <td></td> <td></td> </tr> <tr> <td></td> <td>G</td> <td>28 ± 6</td> <td>6 ± 2 * APO</td> </tr> <tr> <td></td> <td>W</td> <td>28 ± 6 * WT,APO</td> <td>5 ± 2 * APO,UL</td> </tr> <tr> <td></td> <td>APO</td> <td>24 ± 6 * WT</td> <td>38 ± 6 ± OH,UL</td> </tr> <tr> <td></td> <td>W</td> <td>11 ± 2 * WT,OH</td> <td>31 ± 8 ± WT,OH,UL</td> </tr> <tr> <td></td> <td>UL</td> <td>26 ± 12</td> <td>6 ± 2 * APO</td> </tr> <tr> <td></td> <td>W</td> <td>NR</td> <td>NR</td> </tr> </tbody> </table> The mean values (± standard deviation) have been compared for the same support in the other rat conditions (* Acronym in inset represent a significantly difference with other rat condition (one-way Anova with p<0.05, and t-test). WT; Control rats, 6-OHDA; Rats with unilateral degeneration of the whole nigro-neostriatal dopamine neuron system by intracerebral injection of 6-hydroxy-DA, APO; 6-OHDA rats with injection of apomorphine, UL; Rats with a hemilateral labyrinthectomy, G; overground, W; in water, SD Standart deviation, NR; non relevant value. doi:10.1371/journal.pone.0155058.t001 Table 2. Change of the different angles (yaw, pitch, roll) measured during locomotion on both supports for each rat conditions. <table> <thead> <tr> <th></th> <th>YAW H Head vs cervical column (Deg)</th> <th>PITCH H Head vs cervical column (Deg)</th> <th>ROLL H Head vs cervical column (Deg)</th> <th>YAW C1 Cervical vs Thoracic column (Deg)</th> <th>YAW C2 Thoracic vs Lumbar column (Deg)</th> <th>YAW C Curvature of the column (Deg)</th> <th>ROLL Shoulder girdle (Deg)</th> <th>ROLL Pelvic girdle (Deg)</th> </tr> </thead> <tbody> <tr> <td><strong>WT</strong></td> <td>G</td> <td>180 ± 6 * OH, APO, UL (straight ahead)</td> <td>28 ± 6 * OH, UL</td> <td>0 ± OH, APO, UL (straight ahead)</td> <td>180 ± APO, UL (straight ahead)</td> <td>180 ± APO, UL (straight ahead)</td> <td>0 ± OH, APO, UL (straight ahead)</td> <td>0 ± 0</td> </tr> <tr> <td><strong>W</strong></td> <td></td> <td>163 ± 16</td> <td>12 ± 2</td> <td>18 ± 2 * OH, APO, UL</td> <td>155 ± 4</td> <td>162 ± 12</td> <td>60 ± 31</td> <td>4 ± 1</td> </tr> <tr> <td><strong>6 OHDA</strong></td> <td>G</td> <td>162 ± 5 * WT, APO, UL</td> <td>14 ± 4 * WT, APO</td> <td>15 ± 1 * WT</td> <td>156 ± 2</td> <td>166 ± 3 * WT, APO</td> <td>57 ± 1 * WT, APO</td> <td>0 ± 0</td> </tr> <tr> <td><strong>W</strong></td> <td></td> <td>159 ± 6</td> <td>14 ± 5</td> <td>8 ± 5 * WT, UL</td> <td>168 ± 3</td> <td>168 ± 5</td> <td>46 ± 2 * APO</td> <td>7 ± 7</td> </tr> <tr> <td><strong>APO</strong></td> <td>G</td> <td>170 ± 2 * WT, OH, UL</td> <td>26 ± 3 * OH, UL</td> <td>20 ± 2 * WT</td> <td>141 ± 21 * WT</td> <td>149 ± 8 * WT, OH, UL</td> <td>80 ± 15 * WT, OH</td> <td>0 ± 0</td> </tr> <tr> <td><strong>W</strong></td> <td></td> <td>158 ± 8</td> <td>12 ± 10</td> <td>7 ± 6 * WT, UL</td> <td>151 ± 16</td> <td>159 ± 3</td> <td>72 ± 19 * OH</td> <td>11 ± 11</td> </tr> <tr> <td><strong>UL</strong></td> <td>G</td> <td>152 ± 6 * WT, OH, APO</td> <td>12 ± 2 * WT, APO</td> <td>23 ± 14 * WT</td> <td>143 ± 40 * WT</td> <td>166 ± 4 * WT, APO</td> <td>79 ± 52 * WT</td> <td>0 ± 0</td> </tr> <tr> <td><strong>W</strong></td> <td></td> <td>155 ± 17</td> <td>20 ± 10</td> <td>360 ± WT, OH, APO</td> <td>123 ± 38</td> <td>156 ± 16</td> <td>106 ± 56</td> <td>NR</td> </tr> </tbody> </table> Each mean (± standard deviation) angle has been compared with the same angle, same support in the other rat conditions (* Acronym in inset represent a significantly difference with other rat condition (one-way Anova with p<0.05, and t-test). WT; Control rats, 6-OHDA; Rats with unilateral degeneration of the whole nigro-neostriatal dopamine neuron system by intracerebral injection of 6-hydroxy-DA, APO; 6-OHDA rats with injection of apomorphine, UL; Rats with a hemilateral labryntectomy, G; overground, W; in water, SD Standart deviation, NR; non relevant value. doi:10.1371/journal.pone.0155058.t002 After apomorphine injection, the APO-rats placed on the platform exhibited pivoting behavior contraversive to the lesion (Fig 3B). The hindlimb ipsilateral to the lesion was not active, and rotated without having left from the ground, while the hindlimb contralateral to the lesion performed backward steps, and forelimbs acted forwardly and laterally. The footfalls of HLc, FLc, FLi, were as in 6-OHDA inside the trajectory of the head (Fig 4B). The diameter of the circle was not significantly smaller than 6-OHDA (but smaller than WT), however the number of circles per minute and the rotation speed were greatly increased 47 cm/s (Table 2). The PitchH of the APO-rats found again the WT value, while the YawH orientation was nearby to WT but still different from WT and OH. The tilt of the head was higher than previous in WT and 6-OHDA (Table 2). The lateral bending of the vertebral column was higher than WT and 6-OHDA (80°±15), with, as in previous, a significant difference of the YawC2, while the YawC1 did not change (Table 2). The unilateral labyrinthectomized rats (UL) as we previously described [1], presented a 3D deficit. Immediately after recovery from general anesthesia, they were lying on the side ipsilateral to lesion and executed rolling movements about the axis of the extended vertebral column. The rotations took place at the junction between the lumbar and thoracic column. About four hours after surgery, thanks to vestibular compensation [14], UL-rats were able to stand up again. When the UL-rats were placed on the platform, they showed a circling behaviour contra-versive to the lesion (Fig 3C). The diameters of the circles were not different to those of other rats; the rotation speed was slower than APO-rat but not different than the other rats (Table 1). However, at rest, they presented a static postural syndrome oriented toward the side. of the lesion. This syndrome had two components: a rotation about the axis of the thoracic column caused a lateral tilt of the head-neck ensemble. This head tilt (Roll$_{H1} = 23° \pm 14$) was combined with a head rotation about the axis of the cervical column (Yaw$_{H1} = 152° \pm 6$); the utricular macula lesion (UT) caused the head tilt, while the horizontal semicircular canal lesion (HSCC) caused its rotation. At last, the curvature of the vertebral column seemed to not be modified in comparison with injured rats, but less stable (highest SD = 52 for Yaw$_{C}$). In summary, on ground, UL-rats displayed a 3D motor syndrome which concerned their mobility both in a plane related to their basis of support (circling) and to the roll and pitch plane. In contrast, 6-OHDA and APO-rats exhibited a 1D motor syndrome (circling and pivoting) only related to their mobility in a plane related to the support, and the impossibility to move straight-ahead. **Motor behavior in water** When they were placed in the water, the control rats swam close to the edge of the rectangular pool (Fig 3D). The fore limbs were always extended and maintained ahead at the surface, while the hind limbs presented alternate movement as occurs in symmetrical walk. The diameter of the trajectory was compared to the diameter of the pool. The rats, to breathe, maintained their heads above the surface and then modified the Pitch$_{H1}$ (12° ± 2) compared to when over ground (Table 2). Additionally, as they swim close to the edge, they needed to turn at the corner of the pool, and then modified the different yaw angles (high SD for Yaw$_{C2-C}$). The 6-OHDA placed in the pool, circled toward the lesion side (Fig 3E). The diameters of the circles were smaller than WT, as the rotation speed slower in comparison to WT (Table 1). However, the motor behaviour of 6-OHDA rats was not markedly different from the control. When they swim, as was seen in WT, the hindlimbs presented alternate movement as occurs in symmetrical walk, while the fore limbs were always extended and maintained ahead at the surface. The hindlimb contralateral to the lesion showed larger lateral movements than the hindlimb ipsilateral to the lesion (Fig 4C). It was this difference of movement which caused the circling behaviour in the water. The 6-OHDA, like WT, maintained their head stable above the surface with the same Pitch$_{H1}$ and Yaw$_{H1}$, while the Roll$_{H1}$ was different to the WT (8° ± 5). The curvature of the vertebral column and the Roll plane of the girdles were not different from WT (Table 2). Following apomorphine injection, the sense of rotation reversed (Fig 3F) about an axis located at the level of the hind limb contralateral to the lesion. APO-rats swim faster in tighter circles (Table 1). Contrary to control and 6-OHDA, they swim using the hind and forelimbs (S1 Movie), but the coordination of the limbs did not change and was still alternated. A new lateral component was added in the movement of the limbs, with highest amplitude of the limb ipsilateral to the lesion, which induced the pivoting of the APO rats (Fig 4D). The orientation of the head, Yaw$_{H1}$, Pitch$_{H1}$ and Roll$_{H1}$ did not differ from 6-OHDA (Table 2). Accordingly to the tighter circular trajectory, the lateral bending of the vertebral column (Yaw$_{C}$) was higher than in 6-OHDA. The lateral component added by the limb to induce the rotating behavior was concomitant with the change of the roll plane. This movement of the limbs did not change the roll angle of the both girdles, (Table 1). The UL-rats were tested in water three weeks after the lesion, once the circling and the postural deficits observed on ground had recovered. When gently placed in water, UL-rats immediately rolled again about their longitudinal axis toward the side of the lesion and swim away from the surface in random directions (Fig 3G), which obliged one to rapidly rescue them. The Yaw, Pitch and Roll angles seem to not be different from the other rats, but the lack of an observed statistical difference could be because these values had the highest variability (Table 2). In water, proprioceptive afferences related to the plane of support were absent, which obliged the rats to rely on vestibular-related information and vision to control their trim. The reappearance of rolling movements and the problems of navigation at distance from the lesion in UL rats, confirmed that proprioceptive information related to the basis of support are instrumental in the compensation of their 3D motor syndromes. They were used as substitutes for the missing utricular afferences, to control posture in the frontal and sagittal planes and also as substitutes for the HSCC afferences to control navigation. Discussion This study, as explained in the introduction, was aimed at choosing between two hypotheses. One hypothesis is that the dopaminergic system exerts three-dimensional control over motricity, as the vestibular system does. Alternatively, the dopaminergic network, together with neurons processing the horizontal canal information, could control the homeostasis of posture and locomotion specifically in one and only one plane of space, i.e. the plane related to the basis of support. In that case, barrel rolling should never occur, whether at the acute or chronic stage on firm ground or in water. Moreover, circling should have the same characteristics following both types of lesions. Clearly, 6-OHDA and APO-rats never exhibited barrel rolling at the acute stage. They circled at the acute stage of the lesion and continued to do so three weeks later, including in water. In contrast, UL-rats, exhibited both circling and barrel rolling at the acute stage, then only circled on the ground from time to time once compensation had occurred. Furthermore, barrel rolling instantaneously reappeared in water in UL rats, which was not the case in 6-OHDA and APO-rats. That is, the lesion of the dopaminergic system on one side did not compromise trim in the pitch and roll planes, even when proprioceptive information related to the basis of support was lacking as in water. Altogether, these results strongly suggest that dopamine does not exert three-dimensional control of the motor system but regulates postural control in one particular plane of space, the one related to the basis of support. In contrast, as previously shown, the vestibular system exerts three-dimensional control on posture. That is, we show here for the first time a relationship between a given neuromodulator and the spatial organization of motor control. This result is in good agreement with several previous studies. First, none of the studies investigating navigation in the Morris water maze following depletion of the dopaminergic system by unilateral or systemic injection of 6-OHDA or MPTP have mentioned long lasting difficulty in swimming and even less turning. That is, trim in the frontal and sagittal plane is preserved [15–22]. In contrast, mutant rats and mice with abnormal utricular function are known to be unable to swim [23–25] due to barrel rolling. Second, Ishiguro and collaborators [26] studied the Bronx Waltzer (bv) mouse displaying major hearing and vestibular dysfunction and showing a remarkable repetitive circling behavior. They investigated whether this behavior was caused by the asymmetry of striatal function by observing the behavior of the bv mice following microinjection of dopamine D1 agonist, into the striatum ipsilaterally and contralaterally to the preferred direction of rotation separately. We retrieved the same result in Isk-/- mice, years later in a study focused on vestibular neurons in this mutant [27]. A recent paper by Armstrong and collaborators (2015) [28] showed that caspase deficient mice with impaired horizontal semicircular canal function and intact otolithic function circle but do not exhibit barrel rolling. Altogether, our results and those of previous studies show that a congenital lack of vestibular function results in a major asymmetry in striatal function, which in turn is causally related to circling. Finally, this paper confirms unpublished information on the behavior of UL vertebrates and published ones on the behavior of vestibular mutants [23–25], when placed in a tank of water. After a recovery time from the lesion, UL rats displayed erratic navigation, failed to find the surface and exhibited rolling movements, which confirmed that, on ground, proprioceptive information related to the basis of support substituted for the missing vestibular afferences. It explains a- the disappearance of the rolling episodes in UL rats on ground following vestibular compensation; b- the resemblance of their behavior with 6-OHDA and MPTP rats, as only episodic circling episodes persisted. Importantly, the pivoting behavior of the 6-OHDA and APO rats in water was markedly different from that observed on ground: the whole body rotated in bloc in the water instead of pivoting about the axis of the outer hind limb as occurs while on ground and the pattern of the limb movements was quite different during swimming and walking. It shows that the dopaminergic system does not modulate motor control at an immediate pre-motor level. It more likely participates, together with the information encoded by the HSCC, in the alignment of the posture of a multi-articulated skeletal system at rest and in the perception of the straight-ahead direction during navigation. The selective modulation of postural control by dopamine in a plane related to the basis of support is of clear interest at the clinical level. For instance, one of the first signs of Parkinson’s disease is the inability of patients to turn their body about its longitudinal axis when lying in bed. Similarly, at a more advanced stage of the disease, patients get stuck in front of an obstacle. The inability to rotate in a plane related to the basis of support could be at stake in both cases. Another point to examine is the nature of the neuromodulation in the frontal and sagittal planes. Turning has been described for 30 years following intraventricular perfusion of various peptides such as opioids and arginine vasopressine, which could be an indication. Finally, if different types of neuromodulation occur in the different planes of space, the implication in case of pathological mismatch between these different types of modulations remains to be explored. Supporting Information S1 Movie. Pivoting behaviour and 3D head trajectory in the water. Dorsal / lateral and external / internal views of an APO rat pivoting in water. The cutaneous markers allowed following the trajectories of different anatomical units during the swim. Here the trajectory of the snout (in black), and the extremity of the left fore limb, shows that the head is maintained in a horizontal plane and describes a circular trajectory, and the fore limb moves laterally, with alternate movement. 3D anatomical models of head and skeleton have been aligned with respect to the 3D trajectories of markers. These 3D anatomical models have been collected using an accurate micro-CT X-Ray scanner (50 microns accuracy). The 3D anatomical models include a segmentation of the vestibular system, allowing an estimation of the trajectory of the pitch angle of the HSCC. (AVI) Acknowledgments The authors would like to thank S. Deforges, Laboratoire de Neurobiologie des Réseaux Sensorimoteurs for her help in characterizing the lesion of the dopaminergic system. They are also indebted to the members of UMR7179, E. Pellé, who provided attentive care for the animals, T. Décamps and L. Botton-Divet who helped us in making some figures, and K. Boyle who improved the English of the manuscript. This study was funded by grants from the CNRS, Paris Descartes University, the Museum National d’Histoire Naturelle de Paris and the ANR Kameleon (ANR-05MMSA-00002). Author Contributions Conceived and designed the experiments: MH PPV. Performed the experiments: PAL MH RH PPV. Analyzed the data: CS PAL LR. Contributed reagents/materials/analysis tools: LR PAL RH MH. Wrote the paper: MH PPV. Performed surgeries: DE JD CW. References
Hydrogen Decrepitation Press-Less Process Recycling of NdFeB sintered magnets Xia, Manlong; Abrahamsen, Asger Bech; Bahl, Christian; Veluri, Badrinath; Søegaard, Allan I.; Bøjsøe, Poul Published in: Journal of Magnetism and Magnetic Materials Link to article, DOI: 10.1016/j.jmmm.2017.01.049 Publication date: 2017 Document Version Peer reviewed version Link back to DTU Orbit Hydrogen Decrepitation Press-Less Process Recycling of NdFeB sintered magnets Manlong Xia\textsuperscript{1,a}, Asger B. Abrahamsen\textsuperscript{2,b}, Christian R. H. Bahl\textsuperscript{1}, Badrinath Veluri\textsuperscript{3}, Allan I. Søegaard\textsuperscript{4} and Poul Bøjsøe\textsuperscript{5} \textsuperscript{1}Department of Energy Conversion and Storage, Technical University of Denmark, DK-4000 Roskilde, Denmark \textsuperscript{2}Department of Wind Energy, Technical University of Denmark, DK-4000 Roskilde, Denmark \textsuperscript{3}GRUNDFOS A/S, DK-8850 Bjerringbro, Denmark \textsuperscript{4}Sintex A/S, DK-9500 Hobro, Denmark \textsuperscript{5}Holm Magnetic Aps, DK-2800 Kgs Lyngby, Denmark Corresponding Author: Asger B. Abrahamsen, asab@dtu.dk Abstract A Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling method for recycling of anisotropic NdFeB magnets is demonstrated. The method combines hydrogen decrepitation (HD) disintegration of the initial magnet, powder sieving and the Press-Less Process (PLP), where hydride powder is sintered in a graphite mold. Coercivities up to 534 kA/m were obtained in porous samples based on powder size $d < 100$ $\mu$m. Adding a ball milling step resulted in full density isotropic magnets for $d > 100$ $\mu$m. The coercivity reached $H_{ci} = 957$ kA/m being 86 % of the original N48M material without addition of rare earth elements. Highlights: 2) Direct recycling of NdFeB magnets without any addition of material. 3) Magnetic phase diagram determined of recycled magnets produced from both hydride and ball milled powder. Keywords: Recycling, NdFeB sintered magnet, Press-Less Process Abbreviations PLP Press-Less Process HD Hydrogen decrepitation HDDR Hydrogenation Disproportionation Desorption and Recombination NdFeB Neodymium Iron Boron permanent magnets VSM Vibrating Sample magnetometer SEM Scanning Electron Microscopy ICP Inductively Coupled Plasma spectroscopy Acknowledgement The authors would like to acknowledge Dr. Didier Blanchard and Dr. Yunzhong Chen at the Department of Energy Conversion and Storage for assistance on the hydrogenation processing and VSM measurements respectively. This work is part of the REEgain project supported by the Innovation Fund Denmark. 1 Introduction The Nd$_2$Fe$_{14}$B (NdFeB) ferromagnetic alloy discovered in 1983 by Sagawa plays an important role in industrial applications due to its superior magnetic properties[1]. NdFeB magnets are used in a wide range of clean energy and high tech applications, such as wind turbines, electric vehicles and computers[2]. A large effort has been focused on how to guarantee the supply and to reduce the usage of heavy rare earth elements in NdFeB permanent magnets for these applications. With life times of wind turbines of 20-25 years it is expected that large amounts of NdFeB magnets for recycling will become available as permanent magnet direct drive turbines are decommissioned[2]. Thus it is believed that recycling will be increasingly important for the transition of the energy sector towards more renewable sources. There are mainly two methods to recycle NdFeB sintered magnets into new magnets. One is to mill hydrogenated NdFeB powder, aligning, compacting by pressing and finally vacuum sintering[3]. The other is to use the Hydrogenation Disproportionation Desorption and Recombination (HDDR) process to produce anisotropic or isotropic powder, which can be used to produce polymer bonded magnets[4]. The first method can provide high magnetic properties but the cost is almost the same as that of the original magnet. In contrast, the HDDR process may be cheaper, but provides lower magnetic properties. In this paper it is investigated if the Press-Less Process (PLP) [5,6] can be used to recycle sintered NdFeB magnets. The press-less process was developed to improve the coercivity of NdFeB sintered magnets by decreasing the particle size of the initial magnet alloy powder to below 2 µm in order to obtain a higher density of grain boundaries to prevent the movement of the magnetic domain walls [7]. This allowed the removal of dysprosium from PLP magnets for high temperature applications and thereby lifted the dependency of the heavy rare earths [7]. The challenge of using small particles in conventional NdFeB magnet manufacturing is that the powder will tend to get stuck in the pressing die. The press-less process is therefore based on sintering the fine magnetic alloy powder in a graphite mold after a packing of the initial powder to about half of the bulk density of the magnet [6]. The main motivation for using the press-less process for sintering of recycled magnets is that if the initial material is an anisotropic magnet, hydrogen can be used to break up the magnet into smaller particles, that by nature all will be anisotropic, and therefore be possible to align and sinter even if they are about 10 times larger than what is usually used for the press-less process. Secondly, it is expected that the cost of the Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling might be lower than for the original press-less process used with small particle powder, because the demand for high purity gasses for jet-milling and handling atmosphere in the glovebox seems lower due to lower oxidation of the large particles. Compared to the more traditional method based on pressing of the green sample before sintering [8], one can omit a pressing machine, which will also contribute to a cost reduction. 2 Experimental method Fig. 1 shows a schematic description of the recycling process applied. Passivated commercial N48M magnets were used as initial material for the recycling process in order to represent magnets obtained from an end of life product. The magnetic properties of the original N48M magnets are a coercivity of \( H_c = 1114 \text{ kA/m} \), a remanence of \( B_r = 1.39 \text{ T} \) and a maximum energy product of \((BH)_{\text{max}} = 370 \text{ kJ/m}^3\). The composition of the magnets are approximately \( \text{Nd}_{10.7}\text{Pr}_{2.68}\text{DY}_{0.43}\text{Fe}_{79.2}\text{B}_{5.75}\text{Co}_{0.79}\text{Al}_{0.19}\text{Cu}_{0.11} \) (atomic fraction in %) as determined by inductively coupled plasma (ICP) spectroscopy. The microstructure of the initial magnet shown in figure 2 was obtained by Scanning Electron Microscopy (SEM). The N48M magnets were subjected to \( P_{H_2} = 4.5 \text{ bar} \) of hydrogen for 2 hours at room temperature in a sealed container, whereby the magnets were disintegrated into powder as shown in fig 1. A typical hydrogen pressure drop in the order of \( \Delta P_{H_2} = 0.8 \text{ bar} \) indicates that hydrogen was incorporated into the magnet alloy and changed the composition to \( \text{R}_2\text{Fe}_{14}\text{BH}_x \), where \( x \sim 3.5 \). The hydride powder resulting from the disintegration of the N48M magnets was subsequently handled in an argon glovebox in order to avoid oxidation. The HD process resulted in a large fraction of powder with a particle size larger than 100 µm, which is too large to result in a successful sintering. Using a 100 µm, 50 µm and 28 µm sieve the different particle size fractions were separated (Fig 1). The size fractions were filled into \( D_{\text{inner}} = 7 \text{ mm} \) and \( L = 14 \text{ mm} \) cylindrical graphite crucibles and packed by pressing a rod into the crucible to obtain a resulting apparent powder density of \( \rho_{\text{powder}} = 3 \text{ g/cm}^3 \), which is less than half the density of the original magnet \( \rho_{\text{N48M}} = 7.56 \text{ g/cm}^3 \). These samples are termed ‘hydride sample’. In order to improve the amount of powder with a size fraction lower that 100 µm a ball milling step was introduced before the sieving of the powder. The ball milling was done by placing 202 g of hydride powder in a 250 ml ball milling container together with steel balls (188 g Ø10mm, 128 g Ø5mm and 88 g Ø3mm) in argon. The total weight of the balls was 404 g and resulted in a ball to powder weight ratio of 2:1. The powder was milled under argon for 3 hours at 650 rpm in a Fritsch P6 ball mill. The samples prepared from the ball milled powder are termed ‘ball milled’. Some of the samples were aligned with a \( B_a = 1.5 \text{ T} \) slowly ramped magnetic field applied either parallel or perpendicular to the crucible cylinder direction (Fig 1). This was done outside the glovebox, while keeping the samples in an argon filled plastic bag. Samples with powder aligned by an external magnetic field are termed anisotropic, whereas non-aligned samples are termed isotropic. All samples were transported into a vacuum furnace connected to the glovebox and sintered at $T_{\text{sinter}} = 1110 \degree \text{C}$ for 2 hours after first evacuating the furnace to $10^{-4}$ mbar using a turbo pump. Degassing temperature ramps of 2 °C/min (room temperature to 250 °C and 1 hour hold), 2 °C/min (250 to 570 °C and 1 hour hold) and 5 °C/min (570 to $T_{\text{sinter}}$) were used and a cooling rate of 25 °C/min was used after the sintering hold time. The samples were removed from the graphite crucibles by turning them upside down, whereby they fell out since the samples were shrinking during the sintering (Fig 1). Smaller pieces for characterization of the samples were cut using a diamond saw. The magnetic properties of the samples with a typical size of 1 mm$^3$ were characterized using a high temperature option of a vibrating sample magnetometer (VSM) from Cryogenic limited. The microstructure was investigated by Scanning Electron Microscopy (SEM) using a TM3000 from Hitachi after epoxy casting and polishing of the samples. 3 Theory and calculations Normalization of the magnetization measurements was done using the sample mass $m_s$ and the sample volume $V$, whereby the volume magnetization density becomes $$M = \frac{m}{V} = \frac{m \rho_s}{m_s} = M_{\text{int}} \frac{\rho_s}{\rho_{\text{ideal}}} \quad (1)$$ where $m$ is the magnetic moment and $\rho_s$ is the mass density of the sample. In order to compare samples with different densities then the intrinsic properties were obtained by assuming an ideal density of $\rho_{\text{ideal}} = 7.5 \text{ g/cm}^3$, whereby $$M_{\text{int}} = \frac{m \rho_{\text{ideal}}}{m_s} \quad (2)$$ is the intrinsic volume magnetization density as if the sample had full density. Correction for the demagnetization field was made and the resulting internal field was found as $$H = H_a - NM \quad (3)$$ where $H_a$ is the applied field, $N$ the demagnetization factor based on the sample dimensions [9] and $M$ the volume magnetization density. In the following figures the intrinsic magnetization density $M_{\text{int}}$ is shown as function of the internal field $H$. 4 Results The sample dimensions shrink during the sintering and the densities were in the range $\rho_{\text{Hydride}} = 3.7$-6.9 g/cm$^3$ for the hydride samples and $\rho_{\text{Ballmill}} = 7.1$-7.4 g/cm$^3$ for the ball milled samples respectively as listed in Table 1. Fig. 3a-c show the microstructure of the magnets obtained from $d = 50$-100 µm, $d = 28$-50 µm and $d < 28$ µm hydride powder. It is observed that pores are present and that the pore density is decreasing with a smaller particle powder fractions size. The densities of the samples are increasing from 4.6, 5.8 and finally 6.9 g/cm$^3$ for the 50-100 µm, 28-50 µm and $d < 28$ µm size fractions respectively. Thus almost full density samples are only obtained for the smallest size fraction resulting in a rather low yield of the process. Fig. 4a and b show the microstructure of isotropic ball milled magnets made from $d = 50$-100 µm and $d = 28$-50 µm powder. The yield of powder with $d < 28$ µm was very small, because the powder was sticking to the balls and wall of the ball milling container. The images reveal a quite low and similar pore concentration, which is comparable to what is observed for the hydride $d < 28$ µm magnet shown in fig 3c. The low pore concentration is also reflected in densities of the samples based on the ball milled powder being in the range of 7.1 - 7.4 g/cm$^3$. Fig. 5 shows the intrinsic magnetic properties of selected hydride and ball milled samples as well as the original N48M magnet at room temperature $T = 20$ °C. It should be noted that the magnetization curves of the hydride and ball milled samples are isotropic and are shown as the intrinsic properties as if no pores were present in the sample using the method outlined in section 3. The magnetization curve of the original N48M anisotropic magnets with the applied field along the easy axis is also shown for comparison. The magnetic properties of the dry ball milled and the hydride samples of fig. 5 are summarized in table 1 along with the densities of the samples. Fig. 6 is showing the magnetization curve of aligned samples based on hydride powder smaller than 100 µm obtained by sieving. The intrinsic magnet properties are included in table 1. The temperature dependences of the intrinsic remanence and the coercivity of both the isotropic and anisotropic recycled samples and the original anisotropic magnet are shown in Fig. 7. With an increasing temperature, the coercivity and remanence of all the samples decrease as the Curie temperature is approached. When these samples are cooled down to room temperature again, some samples recover their initial room temperature properties. However, that is not always the case for the hydride powder samples and the temperature history is indicated with arrows in Fig. 7. It is observed that the 28-50 µm and 50-100 µm hydride powders do not recover after heating to 160 °C in the vacuum of the VSM sample chamber. However, the sample with a particle size smaller than 28 µm did recover its original properties. All the ball milled samples recovered their initial properties after returning to room temperature. 5 Discussion The mass densities of the HD-PLP samples after sintering are indicating that the hydride powder results in more pores than the ball milled powder, which is confirmed by the SEM images in fig 3 and 4. The pore size seems to be related to the sieve mesh size in case of the hydride powder, but not for the ball milled powder. This is probably, because the ball milling of the powder results in agglomeration of particles smaller than 28 µm as no powder size fraction of $d < 28$ µm was obtained by sieving. Thus, the sieving of the ball milled powder provides the size fractions of agglomerates, which consist of much smaller particles. In previous experiments, the agglomerations stuck to the wall of the container after ball milling strip cast material were examined by dissolving and agitating the agglomerates in ethanol and using a laser diffraction method to determine the size distribution. Those studies indicated that the mean particle size of the agglomerates was in the order 10 μm. Thus, it seems likely that the sieved agglomerates of the ball milled hydrides in the present series consist of such small particles in the order of 10 μm and they therefore sinter into a similar final structure as seen on fig 4. In order to compare the internal properties of the different samples the method of calculating the intrinsic magnetic properties were introduced in section 3. The idea is to compare the volume magnetization density of the material as if there were no pores in order to identify the potential of the recycled magnets. The magnetization curves of fig 5 are showing that the hydride samples have coercivities in the range 300-500 kA/m at room temperature, whereas the samples based on ball milled powder are reaching 950 kA/m. The latter values are approaching the properties of the original magnet having a coercivity of 1114 kA/m and shows that the HD-PLP recycling method is working without any addition of new material or rare earth elements. The remanence ertificate shown in figure 5 is the intrinsic remanence of isotropic samples and this is compared to the anisotropic initial magnet. A simple way to compare an anisotropic to an isotropic sample is to assume that domains of the fully aligned original anisotropic sample preserve their magnetization density M₀ and are put together with random orientation. The measured magnetic moment M_iso will then only be the component M₀sin(θ) projected onto the applied magnetic field direction along the symmetry axis of the pickup coils of the VSM. The density of particles with an orientation angle θ with respect to the coil plane is scaling as cos(θ), whereby \[ M_{iso} = \int_{0}^{\pi/2} (M₀ \sin(\theta) \cos(\theta)) d\theta = \frac{M₀}{2} \] where an integration over the domain orientations is done[10]. From table 1 it is seen that the ratio between the remanence of the HD-PLP samples and the original sample is Bᵣ/B₀ ~ 0.5, which is indicating a full recovery of the magnetic moment of the original sample according to eq. (4). The anisotropic samples obtained from the hydride powder with d < 100 μm have coercivities in the range 490-530 kA/m, which is comparable to the other hydride powder with d = 28-50 μm, but not the d = 50-100 μm. This might be due to a larger fraction of the d = 28-50 μm size is present in the d < 100 μm powder. The intrinsic remanence is seen to increase by the alignment field and the loose powder is easier to reorient than the powder, which is first compacted to an apparent density of 3 g/cm³. The remanence is approaching the values of the initial magnet and further studies have to reveal if a higher alignment field will result in a better alignment of the final samples. It is remarkable that the hydride powder with a size fraction that is much larger than the typical size d = 1-20 μm of jet milled strip cast flake can be aligned by the external magnetic field. We believe this is possible, because the initial anisotropic sintered magnets consist of fully aligned material, which is broken up by the hydrogen decrepitation process into fractures holding many aligned grains of the initial structure. Introducing the hydrogen into the magnetic alloy removes the coercivity of the R₂Fe₁₄B phase, but the magnetic easy axis of the R₂Fe₁₄BHₓ phase still results in a torque large enough to rotate the fractures. The alignment of the ball milled powder has not yet been examined, but it is expected that the agglomeration of the small particles might make the alignment more difficult if the agglomerates are oriented randomly and if they are mechanically welded together. The sintering process is initiated with two degassing steps in order to release the hydrogen absorbed in the hydride powder. The first degassing step at T = 250 °C for 1 hour in high vacuum of 10⁻⁴ mbar is believed to primarily start the hydrogen release from the R₂Fe₁₄BHₓ phase \((R₂Fe₁₄BHₓ \rightarrow R₂Fe₁₄B + x/2 H₂)\) in the grains as well as a first release of some of rare earth element rich phases in between the gains \((NdH₂)\rightarrow NdH₂ + 0.35H₂) [11]. Secondly this step is also intended to remove absorbed gasses or water from the surface of the hydride powder in order to prevent reactions with the powder at higher temperature. The second degassing step at $T = 570 \, ^\circ\text{C}$ for 1 hour is intended to transform the rare earth element hydride phase back into the pure rare earth elements ($\text{NdH}_2 \rightarrow \text{Nd} + \text{H}_2$) \[^{11}\]. The clear advantage of the HD-PLP recycling method is that the low apparent powder density of 3 g/cm\(^3\) of the sample before the sintering is providing a porous structure with a gas percolation path between the particles. The hydrogen from the hydride powder is therefore released more easily than from the green compacts after pressing used in the traditional method for production of sintered magnets. It is believed that the sample contains fractures of the original magnet after heating to $T > 570 \, ^\circ\text{C}$ and that these fractures are re-sintered at higher temperature by the rare earth rich phases, which are expected to have released all the hydrogen. Thus the densification of the samples is first expected to take place after the hydrogen release has taken place. A remaining question is: What is determining the pore size in the magnets if the hydrogen is released before the sintering? This can be addressed by considering a simple packing of identical spheres as shown on fig. 8. If the structure is assumed as simple cubic (SC) packing (fig. 8a) then the volume fraction is $$f_{\text{vol, SC}} = \frac{4 \pi r^3}{a_1^3} = \frac{\pi}{6} \sim 0.52$$ \hspace{1cm} (5) since the unit cell side $a_1 = 2r$. The apparent mass density of such a powder will be $\rho_{\text{SC}} \sim 0.52 \rho_{\text{N48M}} \sim 3.9$ g/cm\(^3\) and is close to the initial packing density of the PLP method. The powder is densified during the sintering and this can be obtained by sliding every second plane of the simple cubic packing structure towards the center of the unit cell, whereby a body centered cubic (BCC) packing results as shown in Fig. 8b. The volume fraction of the BCC packing is $$f_{\text{vol, BCC}} = \frac{2 \cdot 4 \pi r^3}{a_2^3} = \frac{\sqrt{3} \pi}{8} \sim 0.68$$ \hspace{1cm} (6) since $a_2 = \frac{4}{\sqrt{3}} r$. Thus the apparent mass density of such a structure is expected to be $\rho_{\text{BCC}} \sim 0.68 \rho_{\text{N48M}} \sim 5.2$ g/cm\(^3\). One can also estimate the pore sizes $l_1$ and $l_2$ for the BCC packing as illustrated on figure 8b $$l_1 = a_2 - 2r = 2 \left( \frac{4}{\sqrt{3}} - 1 \right) r \sim 0.3 \, r$$ \hspace{1cm} (7) $$l_2 = \sqrt{2} a_2 - 2r = 2 \left( \frac{8}{\sqrt{3}} - 1 \right) r \sim 1.3 \, r$$ \hspace{1cm} (8) If it is assumed that the first part of the densification of the samples during the sintering is caused by a reorganization of the powder similar to the simple cubic to BCC transformation then an estimate of the order of magnitude of the pores size will be related to the diameter $d$ of the particles by $l_{\text{pores}} \sim 0.15 - 0.6 \, d$ as indicated by eq. (7) and eq. (8). Looking at the SEM images of the samples based on the $d = 50 - 100$ $\mu$m hydride powder one would expect $l_{\text{pores}} \sim 8 - 60$ $\mu$m, which is also what is observed. Secondly the expected apparent mass density of the sample should be around 5.2 g/cm\(^3\), which is close to the values listed in table 1. For the $d = 28 - 50$ $\mu$m hydride powder one would expect $l_{\text{pores}} \sim 4 - 30 \mu$m, whereas for $d < 28 \mu$m the pores size is expected to be $l_{\text{pores}} < 4 - 17 \mu$m. Thus for the smaller powder size fraction the pores are getting small enough to support the mass transport of the sintering process, whereby full density samples can be obtained. This analysis also support the observation that all the size fractions of the ball milled powder result in full density samples as shown in table 1, because the particles in the agglomerates have a size around 10 $\mu$m, whereby the $l_{\text{pores}} \sim 6 \mu$m as seen on the SEM images of fig. 4. The final magnetic phase diagram of the HD-PLP magnets in figure 7 shows that the remanence is scaling with temperature as the original magnet for the samples that have full density, but not for some of the hydride samples, which show a decrease in the magnetic properties when cooled down to room temperature. This effect is believed to be caused by the presence of a low but significant concentration of oxygen in the VSM during the measurements. The VSM is constantly pumping on the sample volume in order to provide thermal insulation between the heated aluminum oxide sample stick, where the samples are mounted in an aluminum oxide cup, and the measuring coils of the VSM sitting in the variable temperature insert of the VSM setup. The pressure of the vacuum is estimated to be approximately 10 mbar, whereby the resulting back streaming of oxygen through the pump is estimated to be $p_{\text{O}_2} \sim 10^{-5}$ - $21 \% \sim 2100$ ppm. This is a relatively high concentration of oxygen, which can cause a degradation of the magnetic properties of samples if they are porous. The fact that the samples with an apparent density in the order of 4-5 g/cm$^3$ are showing degradation is seen as an indication that there is a gas percolation path between the particles whereby the oxygen can react with a large fraction of the sample compared to just a surface layer of the dense samples. The origin of the coercivity in the samples is believed to be caused by the original microstructure of the starting N48M magnet material, where rare earth rich phases are separating the $\text{R}_2\text{Fe}_{14}\text{B}$ grains [12]. The introduction of the hydrogen will enter the rare earth rich phases and break up the original structure into fractures [13]. These fractures will lose their magnetic properties due to the hydrogen [11] and the release of this hydrogen during the degassing stages of the sintering might be a factor limiting how much of the initial coercivity that can be recovered. If this picture is correct one would expect an easier hydrogen release and thereby an increasing coercivity with a decreasing fracture size. Looking at table 1 it is seen that the large hydride fractures are resulting in the lowest coercivity and that the ball milled powder consisting of agglomerates of small particles result in the highest coercivity. Thus further work on the optimization of the temperature profile might result in better recovery of the coercivity. 6 Conclusion It has been demonstrated that a new recycling method, which is combining Hydrogen Decrepitation of anisotropic sintered NdFeB magnets with the Press-Less Process, where powder is sintered in graphite crucibles can produce isotropic and anisotropic magnets without any addition of new material. The method is termed HD-PLP recycling due to the combination. Magnets have been produced directly from hydride powder, but do only become dense when the powder size is below 28 $\mu$m. Adding a ball milling step resulted in further disintegration of the hydride powder and dense samples could be produced. The coercivity of the samples reached $H_c = 534$ kA/m and $H_c = 957$ kA/m when based on the hydride powder and ball milled powder corresponding to 48 % and 86 % of the coercivity of the original N48M magnet. <table> <thead> <tr> <th>Preparation</th> <th>Alignment</th> <th>Sieve fraction [μm]</th> <th>$B_r$ [T]</th> <th>$H_{ci}$ [kA/m]</th> <th>Density [g/cm³]</th> </tr> </thead> <tbody> <tr> <td>Hydride</td> <td>Isotropic</td> <td>&lt; 28</td> <td>0.51</td> <td>297</td> <td>6.9</td> </tr> <tr> <td></td> <td></td> <td>28-50</td> <td>0.78</td> <td>499</td> <td>5.8</td> </tr> <tr> <td></td> <td></td> <td>50-100</td> <td>0.72</td> <td>304</td> <td>4.6</td> </tr> <tr> <td>Hydride and ball milled</td> <td>Isotropic</td> <td>28-50</td> <td>0.69</td> <td>957</td> <td>7.4</td> </tr> <tr> <td></td> <td></td> <td>50-100</td> <td>0.69</td> <td>955</td> <td>7.1</td> </tr> <tr> <td></td> <td></td> <td>&gt; 100</td> <td>0.69</td> <td>870</td> <td>7.3</td> </tr> <tr> <td>Hydride Tapped</td> <td>Anisotropic B$\perp$crucible</td> <td>&lt; 100</td> <td>0.92</td> <td>519</td> <td>4.9</td> </tr> <tr> <td></td> <td></td> <td>Anisotropic B</td> <td></td> <td>crucible</td> <td>&lt; 100</td> </tr> <tr> <td>Hydride Loose</td> <td>Anisotropic B$\perp$crucible</td> <td>&lt; 100</td> <td>1.19</td> <td>534</td> <td>3.7</td> </tr> <tr> <td>N48M original magnet</td> <td>Anisotropic B</td> <td></td> <td>easy-axis</td> <td>Bulk</td> <td>1.39</td> </tr> </tbody> </table> Table 1. Intrinsic remanence and coercivity determined from magnetization curves of recycled samples at $T = 20$ °C as shown in figure 5 and 6. The last column is showing the density of the samples. References Figure captions Fig.1. Illustration of the Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling of anisotropic sintered NdFeB magnet. Passivated commercial N48M sintered magnets were used as starting material and hydrogen was applied to disintegrate the magnets inside a ball milling container. The hydride powder was both used directly and some powder was further disintegrated by subsequent ball milling. Size fractions of 28, 50 and 100 µm were obtained by simple sieving of the powder. Different size fraction were filled into graphite crucibles and packed to a density of 3 g/cm³. The powder particles were aligned by an external magnetic field and sintered in a vacuum furnace. The samples were removed by flipping the crucibles, whereby the samples fell out due to the shrinkage during sintering. Fig. 2. Scanning Electron Microscopy (SEM) image showing the microstructure of original passivated N48M magnet used as starting material for HD-PLP recycling. Fig. 3. Scanning Electron Microscopy (SEM) images showing the microstructure of samples made from hydride powder sieved into size fractions and by HD-PLP sintering at T = 1110 °C for 2 hours: a) d = 50-100 µm, b) d = 28-50 µm and c) d < 28 µm. Fig. 4. Scanning Electron Microscopy (SEM) images showing the microstructure of samples made from hydride powder, which was ball milled in argon, sieved into size fractions and HD-PLP sintering at T = 1110 °C for 2 hours: a) d = 50-100 µm, b) d = 28-50 µm. Fig. 5. Magnetization curves of isotropic recycled magnets based on hydride powder sieved into size fractions (full line) and ball milled powder (dashed), as well as the initial N48M anisotropic magnet used as starting material (blue). Fig. 6. Second quadrant magnetization curve of anisotropic samples made from N48M hydride powder with d < 100 µm and aligned in magnetic field of $B_a = 1.5$ T: Loose powder aligned perpendicular to crucible axis with no further packing (black), powder packed and then aligned parallel to crucible axis (green), powder packed and then aligned perpendicular to crucible axis (red) and the original N48M magnet (blue). Fig. 7. Magnetic phase diagram showing intrinsic remanence $B_r$ and coercivity $H_{ci}$ of isotropic ball milling powder recycled magnets (red), isotropic hydride powder recycled magnets (black) and the original anisotropic N48M magnet (blue). Thick lines represent samples with densities above 6.9 g/cm$^3$. The arrows indicate the temperature history of the magnetization of the hydride samples with d > 28 µm observed when first heating (arrow pointing right) and subsequently cooling (arrow pointing left). Fig. 8. Illustration of possible mechanism for densification during the Press-Less Process sintering. a) Arrangement of identical spherical powder particles in a simple cubic (SC) lattice as a suggestion to a representation of the initial packing apparent density of 3 g/cm$^3$ of the PLP sintering. b) The arrangement of a) can be densified by moving every second layer half a unit cell distance, whereby a body centered cubic (BCC) arrangement of the powder particles is obtained. The unit cell lattice parameter is termed $a$, the radius of the particles $r$ and the spacing $l_1$ and $l_2$ are estimates of the pore size in the BCC arrangement. The inset is showing the simple cubic and the body centered particle arrangement in the graphite crucible. End of Life Products Passivated N48M Magnet (R$_2$Fe$_{14}$B) H$_2$ + Ball Mill H$_2$ Decrepitated NdFeB Powder Sieve Sintering in Graphite Crucibles
Session Contents • Introduction (Daniel Pitti) • Archival Entities, Attributes, and Relations Among Them (Gavan McCarthy) • A Bit of RiC by Reusing Old Tools (Bogdan-Florin Popovici) Experts Group on Archival Description (EGAD) • Formed by the ICA Programme Commission in late 2012 • Partial successor to the Committee on Best Practices and Standards (CBPS) • Term 2012-2016; 2016- • Charged with developing a Conceptual Model for Archival Description • Based on four current ICA descriptive standards • Employing formal information modeling techniques # ICA Standards for Archival Description 1988-2008 <table> <thead> <tr> <th>Standard</th> <th>Edition</th> <th>Development Dates</th> <th>Publication Date</th> </tr> </thead> <tbody> <tr> <td>ISAD</td> <td>1&lt;sup&gt;st&lt;/sup&gt;</td> <td>1990-1993</td> <td>1994</td> </tr> <tr> <td>ISAAR</td> <td>1&lt;sup&gt;st&lt;/sup&gt;</td> <td>1993-1995</td> <td>1996</td> </tr> <tr> <td>ISAD</td> <td>2&lt;sup&gt;nd&lt;/sup&gt;</td> <td>1996-2000</td> <td>1999</td> </tr> <tr> <td>ISAAR</td> <td>2&lt;sup&gt;nd&lt;/sup&gt;</td> <td>2000-2004</td> <td>2004</td> </tr> <tr> <td>ISDF</td> <td>1&lt;sup&gt;st&lt;/sup&gt;</td> <td>2005-2007</td> <td>2007</td> </tr> <tr> <td>ISDIAH</td> <td>1&lt;sup&gt;st&lt;/sup&gt;</td> <td>2005-2008</td> <td>2008</td> </tr> </tbody> </table> Archival Principles: Records in Contexts • Principle of Provenance • Respect des fonds • The Records *accumulated* by a person or group in the course of life and work are to be kept together and not intermixed with records from other sources • Respect for Original Order • The intellectual grouping of and sequencing imposed on the records in the context of accumulation and use is essential to understanding the interrelations among them as well as being evidence of how they were used • General international consensus on the principle • But historical, cultural differences in understandings • Records in Contexts • Embodies both facets of the principle • Though more expansive understanding of Provenance • Based on intellectual and practical critique of archival description • Records and the people that create, manage, and use them do not exist in isolation but in complex layers of interrelated, interdependent contexts • In Time ICA Experts Group on Archival Description Context is Complex • *Homo inscribo* – man, an animal that inscribes, writes on, records ... • Records and the contexts within which records are created and used is *irreducibly complex*!! • What is recorded is only a tiny fraction of all of the transactions that take place in the course of life and work, within each person, and among persons • But ... the archivist has the responsibility to preserve the record • Preserving the artifact and ... • Preserving the contexts of accumulation and use of the record • Ultimately the preservation of contexts will be imperfect; contexts are irreducibly complex • Though we have an obligation to make preservation sufficient, to enable users, today and tomorrow, to understand and use the records Context is Complex • RiC aspires to improve our capacity to represent the complexity of the origin and history of records • Conceptual model: representing within the world the objects that are essential for records managers and archivists to fulfill their responsibilities • Model each object of interest (entity) • Model the essential characteristics of each entity (attribute) • Model the relations among the entities (relation) • RiC Conceptual Model represents the world from the perspective of the records manager and archivist • The model is complex, as it is intended to model complex phenomena as fully as possible • Though descriptive tools based on RiC will ameliorate the complexity for users Historical Context • Since at least mid-19th century, cultural heritage communities • Reimagine description in relation to emerging and new communication technologies • Trend • Separate the components of description • To efficiently and more effectively create prevailing access tool (e.g., book catalog, finding aids) • At the same time, enable new tools, new perspectives, new paths, based on recombining the components • Four ICA standards reflect this trend • Though the separation and new perspectives not realized Current and Emerging Technology Landscape • Network, of course, and Markup (XML), and Database (SQL) ... • XML and SQL have dominated but ... • Emergence of Graph technologies: RDF, Semantic technologies and Linked Open Data • More expressive, but also more challenging: complexity, quality ... • Opportunities: separation, recombining, interrelating, opening domain borders, new perspectives, new paths ... • Reposition community to take advantage of the opportunities The RiC Products • Conceptual Model for archival description (RiC-CM) • Documents the key entities of archival description and the attributes of each and the relations among them • With diagrams and examples illustrating how the components are interrelated to form complete archival description • An Ontology for archival description (RiC-O) • Based on RiC-CM • Expressed using the W3C OWL language • Will map archival concepts to similar concepts employed by allied communities: integrated access to cultural heritage • Will enable archival community to participate on its own terms, so-to-speak • Application Guidelines (RiC-AG) • AG will provide implementation guidelines • How it will do so is yet to be determined From ISAD(G) • Predominant form of archival description today • Hierarchical (top-down) description of a single fonds • Description of the whole, the parts of the whole, parts of the parts • Largely if not exclusively self-contained, inward “looking” • That is, not connected to the broader context • All contained in a single apparatus • ISAD(G) a model for this approach; EAD a method for communicating it To RiC: Pivotal Change • Records and aggregations of records treated as two distinct entities • Records • Record Sets • Over the course of its existence, a record may be a member of more than one record set, and at the same time • Multilevel description (hierarchy, a kind of graph) • Multilevel or hierarchical description one among other possible methods of description Multilevel description predominates, and will do so for the foreseeable future: well understood and economic To RiC: Pivotal Change • Multidimensional description (a network graph) • Encompasses multilevel description • Within a network of interrelated records, fonds, people, activities ...: context within context • Enables more flexible description that is more expressive of the complex realities of records than possible in a single hierarchical description • Archival description envisioned as a vast social-document network Current Status of Work • EGAD released first draft of RiC-CM in September 2016 • Open for comments until January 31, 2017 • Public comments from sixty-two individuals and groups representing 19 countries • When compiled, over 200 pages of comments!! • EGAD met in October 2017 in Rome • The majority of the work focused on the comments • The quantity of the comments, as well as the fact that the suggestions were often contradictory, presented and presents a challenge Work Timeline • RiC-CM: Second draft for public comments early in 2018 • RiC-0: Incomplete beta draft early in 2018 • RiC-AG: First draft for public comments in early 2019 • Timeline thereafter variable depending on comments, work schedules … • Objective will be for all three products to be complete and relatively stable late in 2020 Thank you! Over to Gavan Records in Contexts (RiC) An Archival Description Draft Standard INTERNATIONAL COUNCIL ON ARCHIVES EXPERTS GROUP ON ARCHIVAL DESCRIPTION Mexico 2017 Session Contents • Introduction (Daniel Pitti) • Archival Entities, Attributes, and Relations Among Them (Gavan McCarthy) • A Bit of RiC by Reusing Old Tools (Bogdan-Florin Popovici) Using network data curation and visualisation tools to analyse RiC-CM and its broader context. Thanks Daniel But let’s jump in the deep end. Coming to Terms with the Transition from Hierarchies to Open Networks of Entities, Relations and Attributes “Context is Complex” Disclaimer: This graph visualisation of RiC-CM is based on my curation of data representing the conceptual model as at 26 November 2017 – all mistakes are mine – all elegance and meaning is EGADs. Records in Contexts - Informatic Model Discussion release for consultation. Explore the RiC-IM using the indexes on the Browse page. Each entry is hyperlinked to its related Entities, Properties or Relations as defined in the Records in Contexts - Conceptual Model. RiC-IM contains higher level groupings to aid analysis. These do not form part of the formal RiC-CM. If you would like to provide constructive feedback please contact Gavan McCarthy at gavanjm@gmail.com. If you would like to explore a graph visualisation of the model you can do so at https://connex.esrc.unimelb.edu.au and following the link at ICAD. Licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. What do we mean by this? Published by the eScholarship Research Centre, 2016 RiC-IM uses the Online Heritage Resource Manager, a tool developed by the eScholarship Research Centre, part of the University Library at the University of Melbourne. ICA Records in Contexts - Informatic Model v0.2 consists of 394 entries with references to 4 published resources. <table> <thead> <tr> <th>Category</th> <th>Alphabet</th> <th>Entities</th> </tr> </thead> <tbody> <tr> <td>Activities</td> <td>A E P</td> <td>8</td> </tr> <tr> <td>Attributes</td> <td>A C D E F G H I L M N O P Q R S T</td> <td>71</td> </tr> <tr> <td>Attribute Sets</td> <td>D H I L S</td> <td>15</td> </tr> <tr> <td>Domains</td> <td>A E R</td> <td>3</td> </tr> <tr> <td>Entity Sets</td> <td>A E F R S</td> <td>5</td> </tr> <tr> <td>Entity Types</td> <td>A C D E F G J I M O P R S T</td> <td>22</td> </tr> <tr> <td>Explainers</td> <td>A C D E O R</td> <td>28</td> </tr> <tr> <td>Organisations</td> <td>E I</td> <td>2</td> </tr> <tr> <td>People</td> <td>B C E F H I J M P R S T V Z</td> <td>23</td> </tr> <tr> <td>Relation Groups</td> <td>A E F S</td> <td>25</td> </tr> <tr> <td>Relation Types</td> <td>A C D E F G H I M O P R S U W</td> <td>192</td> </tr> <tr> <td>Functions</td> <td>I P Q S</td> <td>26</td> </tr> <tr> <td>Published Resources</td> <td>1</td> <td>4</td> </tr> </tbody> </table> **Record** **Alternative Names** RIC-E01 **Summary** A Record is linguistic, symbolic or graphic information represented in any form, on any durable carrier, by any method, by an Agent in the course of life or work events and Activities. **Details** Such information may serve a variety of purposes, including documenting the events and Activities. Because of its relation to the events and Activities, it serves as evidence for them no matter its quality for use in a particular context. One or more Records in one context may be subsumed or incorporated into a Record in another context to form a new Record. This 'compound Record' should not be confused with a Record Set, as it is evidence of a single transaction by an Agent rather than a grouping of distinct Records as part of their management and use. Examples: Deed appointing John Bambridge, Sheriff of Leicestershire, with 3rd Great Seal of Charles I; Appendix; sketch Map of the Qatar Peninsula; Email message concerning an agreement to participate in the ICA Seoul Congress containing two attachments and digitally signed **Related entries** **Properties** - Authenticity and Integrity RIC-P05 - Classification RIC-P17 - Conditions of Access RIC-P18 - Conditions of Use RIC-P19 - Content Extent RIC-P07 - Content Type RIC-P06 - Encoding Format RIC-P10 - General Note RIC-P04 - Global Persistent Identifier RIC-P01 - History (of Record) RIC-P20 - Language Information RIC-P11 - Local Identifier RIC-P02 - Media Type RIC-P12 - Medium RIC-P14 **Origin for Relation** - conforms to, Archival Resource-Mandate - had creation date, Archival Resource-Date - had holding location, Archival Resource-Place - had part, Entity-Entity - had rights held by, Archival Resources-Agents - has copy, Resource-Resource - has documentary form, Archival Resource-Documentary Form - has draft, Archival Resource- Archival Resource - has holding location, Archival Resource-Place - has missing part, Archival Resource- Archival Resource - has original, Archival Resource- Archival Resource - has part, Entity-Entity - has rights held by, Archival Resource-Agent - has subject, Archival Resource-Entity - is accumulated by, Archival Resource-Agent - is addressed to, Archival Resource-Agent - is annotated by, Archival Resource-Agent - is associated with, Entity-Entity - is authored by, Archival Resource-Agent - is collected by, Archival Resource-Agent - is copy of, Resource-Resource - is draft of, Archival Resource- Archival Resource - is evidence of, Archival Resource-Entity - is held by, Archival Resource-Agent - is managed by, Archival Resource-Agent - is member of, Entity-Entity - is original of, Archival Resource- Archival Resource - is owned by, Archival Resource-Agent - is predecessor of, Entity-Entity ConneX: Contextual Network Explorer Visualise and Explore the Context Entity relationships in an OHRM dataset. A product of the eScholarship Research Centre, The University of Melbourne Library. ICA Experts Group on Archival Description Conceptual model – Informatic model: Representing within the world (Domain) The objects that are essential for records managers and archivists to fulfill their responsibilities - Model each object of interest (Entity) - Model the essential characteristics of each entity (Attribute) - Model the relations among the entities (Relation) From the Current ICA Standards to RiC-CM - Current ICA description standards - ISAD – records - ISAAR – corporate bodies, persons, and families - ISDF – functions, activities, ... - ISDIAH – archival holding institutions - RiC-CM has three top-level entities - **Record Object** (more and less than ISAD, as it focuses just on of records and individual records) - **Agent** (subsumes both ISAAR and ISDIAH) - **Function** (ISDF) ICA Experts Group on Archival Description Primary and Secondary Entities Each of these entities has Attributes, essential characteristics that together make each unique, what it is. For example, a Name or Title, a Date, History ... Record Object - Record (individual record) - Record Part - Record Set (aggregation of records) Agent - Person - Group - Family - Corporate Body - Position (intersection of Person and Group) - Delegate Agent (for example, space and ocean probes and Internet “bots”) Function - Goal (purpose or objective) - Activity - Transaction etc... Space-Time - Place - Date Qualifying Entities Used as Attributes in the Description of Primary and Secondary Entities - Optimally maintained as controlled terms or values - Occupation (of person) - Function (Concept) includes Goal, Activity, Transaction (as concepts) - Record Classification - Documentary Form - Place - Jurisdictions - Geographical features - Latitude, longitude - Complex boundaries - Date - Single date - Date range - Non-contiguous dates - Expression of a date has attributes - Precision of date (uncertainty/certainty) - Calendar system - Standardized form of expression: ISO 8601, or the Extended Date-Time Format Sets (and clusters) of **Attributes** (Properties in RiC-CM 2016) Used in the Description of Primary and Secondary Entities - **Agents** - **Relations** - **Record Objects** - **All Entities** - **Space-Time** Sets of Attributes Used in the Description of Primary Entity Sets Shared Attributes of All Entities e.g. Name and Identifier Name control Authorized or preferred names Alternative names Parallel names Identifier control Global identifier Local identifier Relations Used in the Description of RiC Entities Relations - Kinds of relations among Record Objects, Agents, and Functions, and the sub-entities - Types of relations treated as a graph (broader/narrower; primarily hierarchical but ...) - Directional - Corporate body X has member Person A / Person A is member of Corporate body X - Reduce to a basic and essential set [in RiC-CM 2016 there were 792 registered relations] - Though extensible: general to specific Relations may be qualified by - Place and Date - For example, Person A resided in Place Z from March 1912 until April 1933 This is one of any number of ways that Relations may be usefully grouped. This one is based on a 5 Entity Set Source-Target clustering. Very Elegant. The chaos of reality wins outs against the elegance of models. RiC Relation Types with the Relations Groups ICA Experts Group on Archival Description 79 pages of detailed text reduced to a single parsimonious network graph. RiC Entities, Attributes and Relations only RiC contextualising entities: People Organisations Activities Explainers Over to Bogdan A Bit of RiC By (Re)Using Old Tools ICA Experts Group on Archival Description Starting points • “It may be irrelevant to create multidimensional descriptions, since contexts are infinite. In fact, a record speaks for itself”. • “To implement RiC, we shall need radical new tools” Prerequisites • Archival processing at Brasov County Division of National Archives • Archival Information (Management) System in place, ISAD(G) compliant The target and RiC model Photo of painting of Lucas Hirscher is member of records set type ‘file’ “Album of famous men from Sachsenland” is member of records set type ‘collection’ Brasov Mayor’s Office records is member of records set type ‘fonds’ Photographs and Postcard Collection Archival documentary context (today) Photo of painting of Lucas Hirscher (RiC Record) Is a copy of Painting (RiC Thing) Is painted by Gregorius (RiC Agent/Person) Is examined in Scholar studies Belongs to Friedrich Ridely (RiC Agent/Person) Has subject Lucas Hirscher (RiC Agent/Person) Has living date 1235 (RiC Date) Information/Content context Brasov Mayor’s Office (RiC-Agent/Group/Corporate body) is located in Brasov (RiC Place). The “City Status” (RiC Record) was issued in 1878 (RIC Date). It establishes the Records Unit (RiC-Agent/Group/Corporate body), which is directed by the City Archivist (RiC Agent/Position). ‘Records Regulation’ (RiC Record) was issued in 1881 (RIC Date), establishing Managing archives (RiC-Function/Goal). Provenance context City Archivist (RiC Agent/Position) Friedrich Stenner (RiC Agent/Person) Has position Karl Muschalek (RiC Agent/Person) Has occupation Photographer (RiC Agent/Occupation) created Donation record (RiC Record) Accessioned (loose record set) 1888 (RIC Date) donated ('loose' records set) Photo of painting of Lucas Hirscher (RiC Record) ICA Experts Group on Archival Description **Archival processing context** **Friedrich Stenner (RiC Agent/Person)** Has position of **City Archivist (RiC Agent/Position)** Assembly (loose records) Is assembler of **Photo of painting of Lucas Hirscher (RiC Record)** Is part of bound records set type ‘file’ ‘Album of famous men from Sachsenland’ (RiC records set) Is part of a records set type ‘collection’ **Photographs and Postcard Collection** The current system model Records/record sets As units of description Can be related to Records/record sets Can be related to Records/record sets Can be related to Agents, Functions As descriptors Can be related to Agents, Functions As descriptors Can be related to Records, Agents, Functions Can be related to External resources ICA Experts Group on Archival Description A RiC like approach with old tools ARHIVELE NAȚIONALE BRAȘOV BV-F-00001 Primăria Brașov (1353-1950) BV-F-00001-46 Colecția de fotografii și vederi BV-F-00001-46-PS Album cu oameni renumiți din Ținutul Șașilor (1889-1891) BV-F-00001-46-PS-1 Lukas Hirscher (1235) (-1889.01.08) ### Information on related materials **Publications:** - Portretele patriciatai săseasc din Brașov. Un capitol de artă transilvană (Catalog expoziție Muzeul de Artă Brașov), 2012, p. 10. **Bibliografie (link):** - Referinta tablou Lucas Hirscher ### Additional comments - **Ident instituție/persoană responsab. descriere:** SJAN Brașov/ BF Popovici - **Grad de finalizare:** Finalizat - **Datele creării, revizuirii sau anulării:** 2017 ### Descriptors **Entries:** - Hirscher Lukas (1482-1541) (Antroponime) - Muschalek Karl (1857-1904) (Antroponime\Persoane) - Ridely Friedrich (Antroponime\Persoane) - Editura Albricht & Zillich, Brașov (Organizații\Cultură) **Hirscher Lukas (1482-1541) (Antroponime)** **Base Data** <table> <thead> <tr> <th>Thesaurus:</th> <th>Antroponime</th> </tr> </thead> <tbody> <tr> <td>Name:</td> <td>Hirscher Lukas (1482-1541)</td> </tr> </tbody> </table> **Identification area** <table> <thead> <tr> <th>Tip entitate (ISAAR):</th> <th>Persoană fizică</th> </tr> </thead> <tbody> <tr> <td>Forma autorizată a numelui:</td> <td>Hirscher Lucas III</td> </tr> <tr> <td>Foreign language terms:</td> <td>Hirscher Lucas &quot;der Kleine&quot;</td> </tr> </tbody> </table> **Area of information** <table> <thead> <tr> <th>Collection period:</th> <th>1482 - 4/19/1541</th> </tr> </thead> <tbody> <tr> <td>Administration history:</td> <td>jurast al orașului Brașov 1524</td> </tr> <tr> <td></td> <td>vilic al orașului Brașov 1525-1527</td> </tr> <tr> <td></td> <td>jude al orașului Brașov1527-1541</td> </tr> <tr> <td></td> <td>jude regal 1531</td> </tr> <tr> <td></td> <td>castelan de Bran 1540-1541</td> </tr> <tr> <td></td> <td>A fost trimis în 1528 la împăratul german, la Praga, și în 1530 la Cracovia.</td> </tr> </tbody> </table> | Publications: | Fr. Stenner, Die beamten der Stadt Brasso (Kronstadt), Brasso/Kronstadt, 1916, p. 69 | Ridely Friedrich (Antroponime\Persoane) **Base Data** **Thesaurus:** Antroponime **Name:** Ridely Friedrich **Identification area** **Tip entitate (ISAAR):** Persoană fizică **Forma autorizată a numelui:** Ridely Friedrich **Area of information** **Collection period:** 1/6/1833 - 5/6/1899 **Administration history:** Friedrich Ridely s-a născut la Brasov la 6 ianuarie 1833 și a murit la 6 mai 1899. El a fost fiul părinților Daniel Ridely, originar din Germania, care a devenit proprietarul unei case din strada Nouă (azi Cetatea) nr. 23. Friedrich Ridely a urmat cursurile gimnaziului Honterus până în anul 1848, când a fost angajat mai întâi ca șeică la tatăl său. Ulterior a încotrocit înțelesul de comerciant în privința negoziului de tun și băle Friedrich Honterus, fiind între anii 1838 - 1870 asociatul său. În anul 1859, Ridely s-a căsătorit cu Luise Frederike, fiica mesețului țesător de lână, Josef Graf, însoțită la născerea fiicei în anul 1860 care a decesat, iar în curând și copilul. El s-a dedicat apoi vieții sociale, fiind membru activ în Asociația de țărani și în Asociația germană de gimnastică,ambute înființate în anul 1861. După moartea tatălui său, în anul 1872, și-a compris casa din Târgul Căilelor nr. 2. După căpătarea unui altă pășă în strada Porgă nr. 52, pe care o reconstruirea din temelii între anii 1878-1879, după planurile în-ginerului orașului Brasov, Petrus Bartelt (1842 - 1914). După anul 1870, Ridely a devenit contabil al „Primă Băncă Ardelens din Brasov”, în anul 1877 a devenit membru al noii țări francesiene „La cea cea treia coloană”, atunci căruia a fost păran la sfârșitul vieții sale. În anul 1880, Friedrich Ridely a fost unul din fondatorii Societății Carpaților Transilvani, după care activa în Societatea Apelor Brasovene, înființată în anul 1873, care în anul 1880 a fusionat cu STC. După anul 1881, s-a atașat de nou prim-preot evanghelic Franz Oberl, acționând ca și cuasier și administrator al comunei pentru ridicarea unui monument al lui Honterus (finalizat în anul 1898). De asemenea a fost casierul asociației de sprijin pentru case de educație (Internatul) pentru elevii săși nevoiași. Ridely a devenit și membru fondator al Asociației de sprijin pentru educația din Brasov, înființată în 1884. Neavând obligații familiale, Friedrich Ridely a devenit colecționar. Pe lângă cărti, a colecționat tableuri cu personalități remarcabile din istoria școlară, apoi fotografii ale personalităților din societate al XIX-lea din Brașov, cu ajutorul fotografului Leonid Adler și Carl Mochszid, cărții impărate, timpul postale. Despre colecția de pășări s-a publicat chiar și un catalog tipărit în anul 1880. Prin testamentul său a instituit Comunitatea Bisericescă Evanghelică din Brasov-Cetate ca moștenitor universal, pe oamenă căreia i-a înființat case în „Cetate” și o grădină în Schelă Brasovului, cu condiția să nu fie vândute niciodată. Pe lângă imobil, Ridely a lăsat biserici și o mare sumă de bani (15.000 de coroni), din care s-au instituit printre altele și colțe biserice pentru unii elevi locații ai internatului. După câmparea altor două case pe strada Vălen Lapără (azi Paul Richter nr. 5) facea posibilitatea extinderea internatului. Scaunele de la ecrul evanghelică a primit biblioteca să bogată, colecția de tableuri și de pășări împărate. O parte din colecția lui Friedrich Ridely a ajuns mai înainte în muzeul liceului „Honterus” iar apoi în perioada interbelică în Muzeul Socialist al Țării Bălței. Urmarea celor de-a doua război mondial au distrus în mare parte moștenirea culturală făcută de Friedrich Ridely, numele său fiind menționat astăzi numai pe placile conmemorative așezate pe cele trei case donate bisericii. **Publications:** **Archive plan context** - **ARHIVELE NAȚIONALE** - **BRAȘOV** - **BV-F-00001 Primăria Brașov (1353-1950)** - **BV-F-00001-46 Colecția de fotografii și vederi** - **BV-F-00001-46-PA Album de personalități ale administrațiilor brașoveni (-1916)** - **BV-F-00001-46-PS Album cu oameni renumiți din Ținutul Sângălor (1889-1891)** - **BV-F-00001-46-PS-1 Lukas Hirscher (1235) (-1889.01.08)** - **BV-F-00001-46-CP Cărți poștale ilustrate** **Related units of description** **Related units of description:** - **vezi:** - **BV-F-00001-5-2-1-1881-11258 Regulament privind organizarea arhivei, 1881 (niv.Document)** - **vezi și:** - **BV-F-00001-5-2-1-1889-247 Donația unor fotografii de tablouri de către Karl Muschalek, 1889.01.08 (niv.Document)** --- **Information on identification** <table> <thead> <tr> <th>Ref. code:</th> <th>BV-F-00001-5-2-1-1881-11258</th> </tr> </thead> <tbody> <tr> <td>Ref. code AP:</td> <td>BV-F-00001-5-2-1-1881-8-10</td> </tr> <tr> <td>Title:</td> <td>Regulament privind organizarea arhivei</td> </tr> <tr> <td>Titlu dedus/paralel:</td> <td>Archiv-ordnung</td> </tr> <tr> <td>Creation date(s):</td> <td>1881</td> </tr> <tr> <td>Level:</td> <td>niv.Document</td> </tr> </tbody> </table> Archival processing context Friedrich Stenner (RiC Agent/Person) has position of City Archivist (RiC Agent/Position). Assembled loose records lead to a Photo of painting of Lucas Hirscher (RiC record), which is part of bound records set type ‘file’. ‘Album of famous men from Sachsenland’ (RiC records set) includes Photographs and Postcard Collection, which is part of a records set type ‘collection’. Archival processing context **Information on identification** <table> <thead> <tr> <th>Ref. code</th> <th>BV-F-00001-46-PS</th> </tr> </thead> <tbody> <tr> <td>Ref. code AP</td> <td>BV-F-00001-46-PS</td> </tr> <tr> <td>Former reference codes</td> <td>975/C-176</td> </tr> <tr> <td></td> <td>U940</td> </tr> <tr> <td>Title</td> <td>Album cu oameni renumiți din Ținutul Săsăilor</td> </tr> <tr> <td>Creation date(s)</td> <td>1889 - 1891</td> </tr> <tr> <td>Level</td> <td>niv.Dosar</td> </tr> </tbody> </table> **Information on extent** | Number | 1 | | Extent | 15 file cuprinzând fotografii și însemnări pe verso + 4 file nescrie | | Dimensions W x H (cm) | 18 x 21 cm | **Information on context** Name of the creator / provenance: Album constituit de Friedrich Stener, arhivârul orașului Brașov, în baza reglementărilor arhivistice, din donații de imagini de la fotograful brașovean Carl Muschalek. **Information on content and structure** Contains also: Album cu personalități istorice săsești **Conditions of access and use** Archive/building: BV-B Bălțiul 34 Access regulations: limitat, din rațiuni de conservare; se vor folosi imaginile online Language: germană **Additional comments** Ident instituție/persoană responsabilă descriere: SIAN Brașov/BF Popovici Grad de finalizare: Finalizat Datele creărilor, revizuirii sau anumirii: 2017 **Descriptors** Entries: Stener Friedrich (Anroponime/Persoane) **Stenner Friedrich (Antroponime\Persoane)** **Base Data** - **Thesaurus:** Antroponime - **Name:** Stenner Friedrich **Identification area** - **Tip entitate (ISAAR):** Persoană fizică - **Forma autorizată a numelui:** Friedrich Wilhelm Stenner - **Foreign language terms:** Friz Stenner **Area of information** - **Collection period:** 8/26/1851 - 2/7/1934 - **Administration history:** Friedrich Stenner a urmat cursurile Gimnaziului Honterus din Brașov (absolvent 1871). În anii 1871-1875 a studiat Dreptul la universitățile din Graz și Budapesta. După întoarcerea sa acasă, a fost angajat ca secretar de către orașul Kronstadt și districtul magistrat, a fost apoi numit la notar și din 1877 a condus Registratura Magistratului (Consiliului Local). De la întoarcerea sa la Kronstadt în 1875, Friedrich Stenner a lucrat și la Kronstädtener Männergesangverein. A avut o voce bună de bas și a participat la numeroase spectacole ca solist. Din 1878 până în 1897 a fost, de asemenea, arhivist al asociației și a fost din 1897 până în 1909 adjunct al adunării. La 11 mai 1878, Friedrich Stenner s-a căsătorit cu prima sa soție, Antonia Mieß (1856-1882), care a murit după doar trei ani la vârsta de doar 26 de ani. La 29 iunie 1878, Stenner a fost ales arhivar al orașului și a deținut această funcție timp de un sfert de secol și a câștigat multe merită. În 1887, Friedrich Stenner s-a căsătorit pentru a doua oară, Julie Maria Scheeser (1868-1890). Au avut împreună două fiice în 1889 și 1890, dar soția a murit în scurt timp, la vârsta de 32 de ani. În 1903 Friedrich Stenner a fost ales în consiliul local și a devenit în 1910 primar adjunct. **Bibliografie (link):** - Articol biografic scris de G. Nussbächer - Intrare VIAF Closing remarks • RiC is firstly a new perspective over records • Records description is not only about records, but also about their (many) contexts. Context is far more than the archival one • RiC create the intellectual framework to link archival resources to other cultural information • RiC may require new IT tools to fully express its potential, but with proper mindset, it can be implemented using (some) current instruments Thank you! Over and out
One of a number of 20th century bronze casts of a 1788 original marble sculpture of George Washington by French artist Jean Antoine Houdon, taken off its base from its exterior position in front of the façade of the Chicago Art Institute, and re-installed by artist Michael Asher in the center of the Institute's Gallery 219, a gallery devoted to European painting, sculpture, and decorative arts of the same period. “73rd American Exhibition,” Art Institute of Chicago, 1979. Michael Asher: Context as Content Anne Rorimer The prodigious and protean production of Michael Asher has developed and continues to evolve in critical response to its own definition as art, which perforce is situated within a physical context as well as within an economic, social, political and historical one. During the last two decades Asher has sought ways to engage each work with the relevant aspects of its provided context. In so doing, he has succeeded in freeing his art form the conditions that, in each instance, he chooses to investigate. Two seminal works of 1969 demonstrate Asher’s early involvement with questions of context and his redefinition of established relationships between the object of art and its surroundings. Created for Anti-illusion: Procedures/Materials at the Whitney Museum of American Art and for Spaces at the Museum of Modern Art in New York, these works assumed the form of environmental installations that relied on controlled perceptual conditions. The work of the Whitney exhibition consisted of an invisible plane of air, barely detectable to the touch, which, produced by an air blower concealed in the ceiling, was installed in the passageway between two of the exhibition rooms. It satisfied the theme of the exhibition by taking physical form without visibly intruding on the exhibition space. Similarly, the work for the Museum of Modern Art took its surroundings directly into account. In accordance with the exhibition’s title, Spaces, Asher created a room to be entered and experienced acoustically and visually in relationship to the noise and light levels outside of its walls. As the walls were built especially to absorb sound, visitors’ distance from the exit and entry doors proportionately regulated the degree of exterior sound heard inside. By thus defining the interior space of the work in accordance with its exterior, Asher pointed to the fact that the piece, a hollow container, was not self-contained, but linked with the ambient sounds and lighting in the museum.¹ Two slightly later works, one of 1973 for the Toselli Gallery in Milan, the other of 1974 for the Claire Copley Gallery in Los Angeles, abandoned the methods of sensory control and opened up the entire existing exhibition space as an area for consideration. In order to realize the Toselli piece, Asher requested that all of the many layers of white paint covering the walls and ceilings of the gallery be removed. Four days of sandblasting revealed a rich brown surface underneath many coats of paint, visually uniting the walls and ceiling with the raw surface of the concrete floor. By penetrating the superficial painted surface of the encompassing walls, Asher succeeded in putting the exhibition space itself on view as an object of study and the subject of the work. As Asher has written, “the withdrawal of the white paint, in this case, became the objectification of the work,”² with its content and its container becoming one and the same. For his exhibition at the Claire Copley Gallery, Asher followed a similar procedure of objectification through removal when he took away the internal, free-standing partition of the gallery, which the owner had built to divide the exhibition space from its business area. During the course of the exhibition the owner at her desk and the gallery’s storage were in full view. Asher thus disclosed the inner “works” of the exhibition space by exposing its operations behind-the-scenes. Through the picture window separating the gallery from the street viewers could see the contents of the gallery as the content of the work. From inside the work/space they could observe the external reality outside. Furthermore, because he exposed the day-to-day functions of the gallery in its commercial capacity, Asher simultaneously brought the normally unseen economic underpinnings of both the gallery and the work to the fore. “Just as the work served as a model of how the gallery operated,” the artist has pointed out, “it also served as a model for its own economic reproduction.”³ All subsequent works by Asher similarly have examined the factors that underlie their status as art. Asher’s one person exhibition at the Stedelijk Van Abbemuseum, Eindhoven, as a further example, likewise incorporated the interior spaces of the museum into the body of the work per se. For this exhibition, Asher utilized the rectangular, transparent glass ceiling panels above the gallery space of the museum to create a work that quite literally “took place,” like any exhibition generally, over a period of about a month. Before the opening of the Eindhoven exhibition, fifteen rows of glass panels had been removed from their position in the ceiling above those galleries (comprising half of the museum) that were allotted to Asher for the display of his work. During the beginning of each weekday workmen proceeded to put the glass back in the ceiling. The closing date of the exhibition was not set in advance but, instead, was determined by the number of days required to reinstall all of the panels. The work, therefore, gradually unfolded as the completion of the task drew nearer to a close. The exhibition ended when the last had been repositioned and thus when the exhibition space – whose walls remained free of other works of art for the duration of Asher’s exhibition – was restored to its original condition. The Eindhoven work presented the procedure of presenting exhibitions. If the Copley work specifically made manifest the marketing of art, the work at the Van Abbemuseum turned the exhibition itself into a temporal and spatial event requiring hired labor, which is normally ² Ibid., p.89. ³ Ibid., p.100 provided by the institution but which is not part of the finished work itself. Having filled the exhibition space by emptying it while additionally having defined its own time frame based on actual necessity, Asher’s work turned museum exhibition procedures around in order to simultaneously reveal and escape them. Also in 1977 Asher participated in the group exhibition “Skulptur,” organized by the Westfälisches Landesmuseum für Kunst und Kulturgeschichte, Münster. Unlike the Van Abbemuseum work, which dealt with the nature of the museum exhibition from within the physical confines of the institution’s interior space, the work for Münster confronted the question of producing an outdoor sculpture in relation to a site. For this purpose Asher hired an 11-foot trailer to be parked at nineteen locations during the nineteen-week period of the exhibition. Stationed one week at a time in a succession of different locations within the city of Münster and its suburbs, the trailer moved away from the museum during the first half of the exhibition and back toward it during the second half. In each of its positions, the trailer was juxtaposed and absorbed into a variety of environments, both rural and urban. The otherwise detached trailer, a seemingly self-contained but symbiotic unit linked itself with the community while the museum responsible for the exhibition provided it with its center of gravity. Figuratively anchored to the museum, the trailer delineated the boundaries of a work that encompassed the entire community. The reconstruction of this work for another exhibition, “Skulptur Projekte in 1987 Münster” exactly a decade later, which was organized under the same auspices in the same location and which was based on the same theme of outdoor sculpture, reinforced its original meaning. The replacement of the same kind of trailer in the same series of locations as in the previous exhibition was designed to foreground changes or growth in the city. At the same time, the reinstallation of a former work (otherwise unprecedented in Asher’s career) provided a contrast – even greater than ten years before – with other works of outdoor sculpture that, for the most part, clung to the nearby environs of the museum without venturing to question the traditional nature of a sculpture as a physically detached object in space. Like the works preceding it, the Münster piece of 1977, and again of 1987, integrated the material work with its support, and, furthermore, expanded the definition of its support to include not only the interior of the exhibition space, but also the institutional domain of the museum as part of, but distinct from, the non-art environment of the city at large. Two works by Asher of 1979 coincidentally exhibited at separate museums in Chicago simultaneously – at the Museum of Contemporary Art and the Art Institute of Chicago – investigated relationships between sculpture and architecture, on the one hand, and between the work of art and its institutional support on the other hand. In each instance, Asher dealt with the work’s container as this is to be both architecturally and institutionally understood in order to further question and redefine the nature of traditional sculpture. The work for the Museum of Contemporary Art, Chicago, was realized in response to this institution’s decision to remodel and expand its building and to form a permanent collection which it began to acquire after celebrating its 10th anniversary in 1977. The design of the current building is based on a five and one-half foot square module, which is expressed on the façade by brushed stainless steel panels that cover the concrete block structure to create a decorative grid pattern. These panels, applied to the flat face of the museum turn the east corner of the building. From an angle, one is able to observe how they encase and wrap partly around the façade and stop short of the underlying structure of the original edifice. --- The original building, a bakery later converted to the offices for underlying Playboy magazine, was first remodeled by the Museum of Contemporary Art in 1966. The architects at this time transformed the front of the museum through the application of stucco to what was then a brick façade. When confronted with the problem of connecting the existing museum to an adjoining three-story brownstone house annexed in the following decade, the new architects, Booth, Nagle, and Hartray, added a structure in front of the two buildings, unifying them in a single façade that replaced the former building’s more modest stucco exterior. The most prominent feature of this added façade was a new entrance and a second story, trussed gallery that “functions as a showcase so that the art is visible from the street,” as Asher specifically noted.\(^5\) The two rows of glass windows of the trussed gallery carry through the five and one-half square-foot modules of the decorative grid pattern and line up with the two rows of stainless steel panels on either side of it. In the printed statement accompanying his work, Asher described the fact that he unhinged the two rows of panels that flank the showcase windows and reinstalled them on the wall of the interior exhibition area, known as the Bergman Gallery. As he pointed out, “The ten panels from the east side of the building and the eight from the west are arranged inside so that they correspond exactly to their previous positions outside.”\(^6\) The double row of panels from the east side of the building, as a group, required 22 feet of wall space from the west and 24 3/4 feet from the east, allowing 30 feet of blank wall space for the work of other artists. When the metal panels from the building’s exterior are not on view in the Bergman Gallery, the work is “in public storage”\(^7\) and, having once again become an inseparable part of the building, it disappears until its subsequent installation.\(^8\) When the work – visible in its entirety from the outdoors – is on view, the rectangular units of metal cladding, facing toward the street from within the Bergman Gallery, must be considered from their position inside the museum. Aligned on the wall as would be any museum display, the panels assume the characteristics of art. Thus hanging together, they present themselves in the form of an abstract, metallic relief whose repeated, serial components evoke the industrial and reductive qualities of Minimal sculpture as defined in the 1960s by artists such as Carl Andre, Donald Judd, or Sol Lewitt. While they are read from inside the museum, in light of their visual association with Minimal sculpture, the panels, in addition, underscore their decorative and non-structural function on the exterior of the building where they serve to cover up the materials of the original supporting structure beneath a sleek and shiny façade. With the power of the museum context being brought to bear on the content of the work as a whole, architectural decoration and the elements of sculptural form here become interchangeable. The work for the Art Institute of Chicago – a large general museum, renowned for its collections ranging in date from ancient times to the present – represented Asher’s participation, along with fifteen other artists in its “73rd American Exhibition.” Over the years this biennial exhibition has provided the museum with the opportunity of regularly presenting current art. In parallel manner with the work at the Museum of Contemporary Art, the work for the American Exhibition similarly used and expressed the underlying and unspoken role played by the museum context in organizing modes of aesthetic perception. And once again, the museum as an object of --- \(^6\) Ibid. \(^7\) Asher, Writings, p. 197 (photo caption). \(^8\) This work was acquired by the museum for its permanent collection and may be reinstalled at any time, although to date it has not been put on view again. investigation provided, both physically and ideologically, the material for a work of art that resulted from the repositioning of actual elements belonging to the existing architectural reality. For his work in the “73rd American Exhibition” Asher removed a life-size, green patinated, weathered bronze statue of George Washington from where it had stood at the main entrance of the Art Institute of Chicago for over half a century and repositioned it within the museum. The sculpture is one of a number of 20th century casts of the original marble of 1788 by the well-known 18th century French artist, Jean Antoine Houdon. Heretofore the bronze had served as a commemorative monument to the first president of the United States, dressed as a leader of the American Revolutionary War, and also a decorative object that had been firmly ensconced on its stone pedestal in front of the central arch of the Art Institute’s neo-Renaissance façade. The sculpture of Washington was taken off its base and installed by Asher in the center of Gallery 219. At this time Gallery 219 was devoted to European painting, sculpture, and decorative arts of the late 18th century, that is, to works of the same period as the sculpture by Houdon. Relatively small and nearly square, the room was painted a gray blue-green color and contained works of art that had been symmetrically placed around the gallery and on the walls from floor to ceiling in the attempt to evoke, however artificially, the sense of an original period setting. In a short text for guiding visitors between the American Exhibition on the first floor and Gallery 219 on the second, Asher stated: “In this work I am interested in the way the sculpture [of George Washington] functions when it is viewed in its 18th-century context instead of in its prior relationship to the façade of the building… Once inside Gallery 219 the sculpture can be seen in connection with the ideas of other European works of the same period.” The relocation of George Washington from its centralized, exterior position in front of the building’s façade to its centralized position in Gallery 219 refined the sculpture’s meaning vis-à-vis the nature of its new context. Dismantled from its pedestal and divested of its imposing, outdoor monumentality and decorative function in relation to the Art Institute’s façade, the sculpture inside the museum had to be viewed in terms of the other works of art encompassing it. Although on historical, stylistic, and formal grounds the sculpture belongs in Gallery 219, it nonetheless subtly, and humorously as well, sounded a discordant note. The mediocre quality of the cast along with the weathered look of its patinated surface (coincidently, however, nearly blending in with the blue/green color of the gallery walls) did not permit the sculpture of George Washington, the “Father of his Country,” to be completely and unquestionably absorbed into the domain of the gallery despite the statue’s period credentials. Although an outdoor sculpture of an American hero par excellence took its place stylistically amid European works of its own time, it injected a sign of discontinuity. Standing within the gallery George Washington served as a reminder of the selection, categorization, and contemporary repositioning that effect the way in which the past is re-created within the confines of the museum with respect to the nature and limits of its holdings. For the construction of this work, Asher followed standard museum procedures of installing works of art – which have been extracted from the original conditions of their conception and placement – within designated areas of the museum in chronological sequence and/or geographical groupings to bring about a new environment. As a result, he succeeded in creating a work that could not in itself be subjected to ensuing relocations and contextual dislocations. Asher’s work thereby circumvented the institutional procedures upon which it, paradoxically, was founded and to which it critically drew attention. The “73rd American Exhibition” constituted the immediate context of this work as Asher himself explained in the written handout: in the process of “locating the sculpture within its own time frame in Gallery 219, I am placing it in the framework of a contemporary exhibition, through my participation in that exhibition.” Thus, not only did Asher exempt his work form the consequences of historical uprooting and repositioning, but he also connected and integrated a contemporary work of art – conceived for an exhibition aimed at presenting examples of the most recent artistic production – with the museum as a whole. As well, he was able to engender a work that was grounded in the past, which it literally embodied in a concrete, material form. Rather than merely quoting or borrowing from the past in a Post Modern fashion, Asher’s work, instead, radically departed from the previous forms of aesthetic practice. Bearing witness to the realities of its broader context within the museum and within history of art in general, the work for the “73rd American Exhibition” allied the production of art in the present with that of the past to achieve its own innovative ends. Whereas the American Exhibition furnished the contextual framework for Asher’s work, the entirety of Gallery 219 with the sculpture of George Washington at its center defied the work as a material whole. During the installation of this work, however, Gallery 219 never ceased to serve the purpose of displaying 18th century objects of art. For this reason, the space of the work and the “real” space of the gallery coincided with each other. Asher, therefore, succeeded in erasing the traditional division between a material object and its physical setting. By extension, the paintings on the walls, necessarily retaining their status as art, also became elements of the existing reality by way of their incorporation into another work of art. Moreover, Asher’s work, quite astonishingly, inverted traditional perspective in that the paintings on the walls became reality-in-the-context-of-art as opposed to reality being transformed into art-in-the-context-of-reality. At the same time, the centralized figure of Washington, deprived of its former purpose as a monument, served simultaneously as the catalyst for another work of art and as a point of reference for, or a reminder of, the traditionally isolated a detached work of art that Asher had subverted. Ensuing works by Asher have remained contingent on existing reality and the conditions of their presentation. A relatively recent work, for the “74th American Exhibition” at the Art Institute of Chicago in 1982, specifically expressed the vital function of the museum as an institution for exhibiting art. For this work – initially proposed for the Institute’s permanent collection – he engaged two groups of viewers to stand at a designated time (for practical purposes only) each day in front of two different paintings in the permanent collection galleries: specifically, *Nude Seated in a Bathtub*, 1910, by Marcel Duchamp and *Portrait of Kahnweiler*, 1910, by Pablo Picasso. Asher selected these two particular paintings because of the disparate degree to which they had been reproduced in books, on posters or on postcards, etc. – the Duchamp hardly at all and the Picasso extensively – and disseminated in the public domain as the second-hand images. Thus installed in front of two paintings in the same room, the “model” viewers, paradigmatic of museum visitors, demonstrated the point at which the museum’s role to present, and the visitor’s to perceive, intersect. Paradoxically, the same institutions that make original works of art available to the public are also those that provide photographs and reproductions. Seeking to dismantle the barriers to direct perception engendered by reproduction, with its capacity to substitute for, and dull, the experience of the original, Asher’s work reproduced the process of viewing that takes place in a museum as a concrete actuality. Rather than being a work, however, that was physically and conceptually independent of its institutional context – yet nonetheless dependent on it for its display – it was a work that could not be detached from the existing situation it sought to acknowledge and consider. Having abandoned the convention of sculpture in the round, the work revolved around the viewing process by materially and thematically embodying it. During the decade of the 1980s Asher has continued to create works that materialize in response to the physical, institutional, geographic, and/or historical circumstances that pertain to their own making. Complex works for the Los Angeles County Museum of Art, 1981, the Walter Phillips Gallery of The Banff Centre School of Fine Arts, Canada, 1981, and the Hoshour Gallery, Albuquerque, New Mexico, 1984, to mention only several, have employed textual and photographic material while a work of 1988 for Artists Space, New York dealt directly with the given interior of the exhibition area. For his work at Artist Space Asher vertically extended the partial walls of the encompassing space, which followed the outline of the original perimeter walls but which stopped 12 feet short of the ceiling. These walls, lining the interior spatial shell, had been recently constructed during a period of remodeling and, prior to Asher’s extensions, had inserted their own physical, volumetric presence into the viewing space. Asher’s extensions were not painted during the exhibition, but they nonetheless succeeded in “restoring” the space to a neutral state and in revealing the sculptural pretense of architecture that diverges from its self-effacing nature as a background for art. As sculpture, the work by Asher blended in with the exhibition space by being integrated with it and commented, moreover, on the impositional potential of architecture with its tendency to masquerade as art. At the close of the exhibition the mural extensions constituting the work were not dismantled, but, rather, were painted over to completely merge with and be absorbed into the exhibition space as a whole – a fitting conclusion to a work that involved the interface between use, value and aesthetic purpose. As in Asher’s works for the Museum Haus Lange, Krefeld9 and for “Documenta 7,” Kassel, both done in 1982, sculptural content was produced by the supporting walls of its own architectural context. In each of his works to date Michael Asher has successfully endeavored to mend the division between form and function and between real and artificial space. Having redefined the traditional relationship between the material of the work and its spatial support, Asher has reinterpreted the conventional notion of sculpture as an autonomous, “free” standing object. To this end, he consistently has made works that manifest the desire to destroy illusion – including that of the work itself – through the removal of all obstacles hindering perception. Anne Rorimer Chicago, June 1990 © Anne Rorimer is author of New Art in the 60s and 70s Redefining Reality which was published in 2001 and recently released in paper back. She is the former curator of twentieth-century painting and sculpture at the Art Institute of Chicago and co-curated the exhibition Reconsidering the Object of Art: 1965-1975, organized by The Museum of Contemporary Art, Los Angeles, in 1995. ---
1. Introduction. - **Goal:** to account for the agreement mismatch illustrated in (1): a morphologically singular DP subject triggers plural agreement on the verb.7 (1) a. [np [d El] [n1 hornero] [n2 hornera]]] cobraban en panes. ex. thebakers,SG and bakers,SG were-paid,PL in bread loaves b. [np [d [np cuya]] [n1 detención] [n2 interrogatorio]]] fueron llevados a cabo por inspectores. ex. whose,SG arrest,SG and interrogations,SG were-carried-out,PL by inspectors - **Theoretical claims:** (2) (i) The notion of phi-features generally assumed in the P&P/Minimalist framework is insufficient to explain complex agreement facts. There are two kinds of phi-features involved in agreement operations (purely formal phi-features and semantic phi-features). (ii) Features are organized in bundles. Agreement operates on bundles (Maximization Principle, Chomsky 2001). (iii) Agree must be understood as feature sharing (Frampton and Gutmann 2000). Agree applies both DP internally (Concord) and externally (in subject-verb agreement, generally associated with case assignment). The distinction Concord-Agree should be eliminated (in the line of Carstens 2000). 2. The data. 2.1. Basic examples. - The structure introduced in (1) is widely attested and productive in Spanish. - All kind of nouns and determiners participate in this construction. - All the examples in these series are corpus data extracted from CREA 3. Our proposal. 3.1. Preliminary assumptions. Asymmetric CoP. 3.2. An enriched theory of phi features. 3.3. Agree as feature sharing. 3.4. Against a DP ellipsis approach. 4. Prospects and Conclusions. --- 7 The research underlying this work has been supported by the Spanish Ministerio de Ciencia e Innovación through a grant to the Projects AC/HUM2007-30541-C, FFI2009-07114 (subprograma FILO) and EDU2008-01268/EDUC. --- 1 This work is part of a wider investigation on agreement inside DPs, in which we analyze number agreement between D, A and N in structures where a conjunction of singular Ns receives a plural interpretation. (see Demonte & Pérez-Jiménez 2010) --- 2 a. [D A [N1, y N2]]] b. [D [N1, y N2] A] c. No es descabellado pensar que esa desconfianza e inseguridad eran el origen de los estados de melancolía. ‘It is not crazy to think that this distrust and insecurity gave rise to those states of melancholy.’ d. Toda persona y pueblo tienen derecho a saber qué pasó con sus seres queridos. ‘Every person and people have their right to know what happened to their loved ones.’ 2.2. Obligatory CCA. • Closest Conjunct Agreement is compulsory in these structures. (6) {El/*la/*los/*las} horneron a y hornera a cobraban en panes. ‘The baker and baker were paid in bread-loaves. 2.3. Plural semantics. • These DPs are semantically plural: they denote a set of individuals, more strictly, a ‘plural individual’, Lasersohn (1995). (7) Se les atribuirán un nuevo padrino y madrina, quienes deben darle la instrucción necesaria en el arte de la brujería. ‘They will be assigned a new godfather and godmother, who must instruct them in witchcraft. • They give rise to distributive as well as to collective readings (Lasersohn 1995). (8) Distributive reading: Su marido e hijo hablan francés / son altos. ‘Her husband and son speak French / are tall. (9) Collective reading: Su marido e hijo se reúnen / se encuentran ayer. ‘Her husband and son gathered / met yesterday. • Other syntactic contexts forcing the distributive, (10), and collective readings, (11). (10) COMBINACIÓN CON DIFERENTE [Su marido e hijo / La policía y gendarmería / El propano y butano / La claridad y oscuridad] llegaron en diferentes momentos. ‘Her husband and son, the police and gendarmerie, the propane and butane, the brightness and darkness arrived at different moments.’ (11) CONTEXTOS GIVING RISE TO THE COLLECTIVE READING: a. COMBINATION WITH SIMILARITY PREDICATES Su marido e hijo son parecidos. ‘Her husband and son are similar.’ b. COMBINATION WITH JUNTOS ‘TOGETHER’ [La madre e hija / La policía y gendarmería / La claridad y oscuridad] vinieron juntos. ‘Her mother and daughter, the police and gendarmerie, the brightness and darkness came together.’ c. COMBINATION WITH MISMO ‘SAME’ (LICENSED BY SEMANTIC PLURALS) [Su marido e hijo / La policía y gendarmería / La claridad y oscuridad] llegaron en el mismo momento. ‘Her husband and son, the police and gendarmerie, the brightness and darkness came at the same moment.’ d. BINDING OF RECIPROCALS Su marido e hijo se quieren (el uno al otro). ‘Her husband and son love each other. • A coordination of Ns can also have a singular denotation, correlated with singular agreement on the verb when the DP is a subject. (King & Dalrymple 2004: 75-6: the distinction is tied to the semantics of the conjunction and). 3. Our proposal. 3.1. Preliminary assumptions. Asymmetric CoP. • D selects for a Coordination Phrase [CoP] with the first conjunct, N₁, c-commanding the second one, N₂ (Kayne 1994; Johannessen 1996, 1998; Camacho 2003 for Spanish). (13) La madre e hija cruzaron una serie de miradas. ‘The mother and daughter exchanged a series of glances.’ We remain neutral with respect to the level of projection of Ns: N₀ or NP. There are no functional projections hosting morphosyntactic number and gender features in the DP structure. These are considered features of N. (For a discussion on the position/projection of the number feature, see Dobrovie-Sorin (2009) and the references therein). 3.2. An enriched theory of phi features - P&P/Minimalist tradition: syntactic agreement operates with phi features (a short history of phi features can be found in Adger & Harbour 2008). - Our claim: the notion of phi-feature set as generally understood is not enough to explain the facts we are describing. The theory of phi features must be enriched. (14) Two sets of phi-features, both visible to the syntactic component: a) Concord Phi-features are formal features related to the morphosyntactic properties of lexical items and codify instructions to the PF interface. b) Index Phi-features are formal features related to semantic properties of lexical items and codify instructions to the LF interface. (15) Mixed agreement: This band are absolutely amazing (from W&Z 2003:76). - Featural content of N, D and CoP: - Nouns. - Concord features: reflect declensional properties of N: gender, number and case -all nouns have an abstract case feature-. - Index features: reflect semantic properties of N. W&Z 2003: nouns are associated with indices, conceived as feature structures: gender (associated with sex or other semantic categorization), number (cardinality), person (identification of participants). - Both concord and index phi-features are valued in N, except for the Case feature. (16) a. Noun <table> <thead> <tr> <th>concord-features</th> <th>index-features</th> </tr> </thead> <tbody> <tr> <td>gender</td> <td>GENDER</td> </tr> <tr> <td>number</td> <td>NUMBER</td> </tr> <tr> <td>Case</td> <td>PERSON</td> </tr> </tbody> </table> b. madre | hija \[i[\{f\}\{n\}p\{3\}]\] \[i[\{f\}\{n\}p\{3\}]\] c[i[\{f\}\{n\}c\{1\}]] c[i[\{f\}\{n\}c\{1\}]] - Determiners. - Concord features: declensional properties of D: unvalued gender, number, case. - Index features: unvalued gender, number, person. Motivation: determiners semantically operate onto the noun’s index. - Both concord and index phi-features are unvalued in D. (17) a. Determiner <table> <thead> <tr> <th>concord-features</th> <th>index-features</th> </tr> </thead> <tbody> <tr> <td>gender</td> <td>GENDER</td> </tr> <tr> <td>number</td> <td>NUMBER</td> </tr> <tr> <td>Case</td> <td>PERSON</td> </tr> </tbody> </table> b. D \[i[\{f\}\{n\}p\{1\}]\] c[i[\{f\}\{n\}c\{1\}]] - Coordinate phrase: (18) CoP \[i[\{f\}\{n\}p\{3\}]\] N₁ \[i[\{f\}\{n\}p\{3\}]\] Co \[c[i[\{f\}\{n\}c\{1\}]]\] N₂ \[i[\{f\}\{n\}p\{3\}]\] c[i[\{f\}\{n\}c\{1\}]] Recapitulation: Featural content of N, D and CoP. La madre e hija cruzaron toda una serie de miradas. The mother and daughter exchanged a series of glances. 3.3. Agree as feature sharing Point of departure: Agree – Feature sharing Agreement within the DP - (22): D, with unvalued phi-features, probes for a goal with their valued counterparts. - Index and concord phi-features are treated by syntax as bundles (Maximization Principle). - The index features of D agree with their closest goal containing matching features: CoP. D is ‘indexically’ plural. - The concord features of D find their closest goal in the concord features of N1. The feature bundle on CoP is overlooked since this bundle does not “maximally” match the one on the probe: Closest Conjunct Agreement. D is morphologically singular. - Structural Case is unvalued in N. This is not a problem if Agree is understood as Feature Sharing: Agree is realized as the sharing of a single feature between two syntactic nodes, regardless of whether the feature is valued or not. - D ends up with its index features valued and one of the features of the concord set still unvalued. Implications: (a) Agreement is established with independence of Case assignment. (b) Goals need not to be ‘active’ in Chomsky’s sense (cf. CoP). - Agree theory in the line of Frampton & Gutmann’s proposals. - Unified treatment of Agree and Concord (in line with Carstens 2001, a.o.). Subject – Verb Agreement - T(ense) merges with the verbal phrase containing the subject DP. - T bears a concord bundle which contains at least person and number features (for the sake of simplicity we assume that it also has a gender feature, although it is not visible in Spanish). Verbal agreement systems evolve historically from pronoun incorporation (on this typological claim, see Wechsler & Zlatić 2003: 90, Nikolaeva 2003: §1, and the references cited therein). Person and number are concord features on T: they correspond to the inflectional properties of the verb and are visible at PF. • The unvalued concord features of T probe for a matching set of features and find the index features of DP. This is possible given that concord and index features are different kind of features from the point of view of the interfaces, but not from the point of view of syntax. A concord bundle can agree with an index bundle as long as they contain the same featural content. • The number feature of T is valued as plural. As a consequence of agreement the Case feature of D (shared with N) is valued as nominative (Chomsky 2001, Frampton and Gutmann 2000 a.o.). 3.4. Against a DP ellipsis approach. • Camacho (2003) [see also Chaves 2008: 270]: ellipsis based account: two DPs are conjoined and null D and A are licensed in the second DP under identity with D and A in the first DP. (24) a. La flora y relieve (me sorprendieron mucho). ‘The flora and relief (astonished me).’ b. [DP D N] y [DP ØD N] (25) a. La fascinante flora y relieve (me sorprendieron mucho). ‘The fascinating flora and relief (astonished me).’ b. [DP D A N] y [DP ØD ØA N] In this kind of approach it is difficult to explain the following facts. • Ellipsis of A in the second DP is dependent of ellipsis of D. (26) a. * [DP D A N] y [DP ØD ØA N] b. La fascinante flora y el relieve ≠ La fascinante flora y el fascinante relieve ‘The fascinating flora and the relief’ ≠ ‘The fascinating flora and the fascinating relief’ • N in the second DP cannot be deleted. It must be obligatorily a remnant for the structure to have a plural interpretation. (27) a. * [DP D A N PP] y [DP ØD ØA ØN PP]. (impossible with plural interpretation) b. La hermosa mujer de Pedro y de Juan. ≠ La hermosa mujer de Pedro y la hermosa mujer de Juan ‘The beautiful woman of P. and of J.’ ≠ ‘The beautiful woman of P. and the beautiful woman of J.’ 4. Prospects and Conclusions Prospects (28) Italian a. *[Un uomo e bambino] mangiano. [H&Z 2005: (21a)] _a_{M.SG}, man_{M.SG} and child_{M.SG}, eat_{PL}_. ‘A man and child are eating.’ b. *[Questo uomo e ragazzo] sono buoni amici. [H&Z 2005: (21b)] _this_{M.SG}, man_{M.SG} and boy_{M.SG}, are_{PL}_, good friends_. ‘This man and boy are good friends.’ (29) French *[Ce soldat et marin] étaient d’accord. [H&Z 2005: (22b)] _this_{M.SG}, soldier_{M.SG} and sailor_{M.SG}, were_{PL}_, in-agreement_. ‘This soldier and sailor agreed with each other.’ (30) Romanian *Acest bărbaț și femeie sunt îndrăgostiti. [Dobrovie-Sorin 2009: (11)] _this_{M.SG}, man_{M.SG} and woman_{F.SG}, are_{PL}_, in-love_. ‘This man and woman are in love.’ We have shown that these structures exist in Spanish (Villavicencio et al. offer similar data for Portuguese). Question: ¿Is there really a parametric difference? • Hypothesis (tentative and preliminary): ¿Could Spanish be considered a language where Ns can be arguments without the presence of D in some contexts? (note the contrast between *Madre llegó and Madre e hija llegaron). On the lack of correlation between DP-hood and argumenthood, see Aboh (2010) and the references cited therein. (31) Es un excelente iniciativa (el) que vengas al menos una vez al año. ‘The fact that you come at least once a year is an excellent initiative.’ 3 Although clarification is needed in this respect, examples like (i) are attested in Romanian, and some examples of this type in French can also be found on the Internet. (ii) Plank (1991) consider examples like ton père et mère ‘your_{PL} father and mother’ as grammatical (as also ses père et mère ‘your_{PL} father and mother’). (i) Sotul și copilul sau au plecat [Elena Soare (p.c.)] husband.the and son.the her SG have PL left ‘Her husband and son have left.’ _its fauna and flora exceptional and unique_. ‘Its exceptional and unique fauna and flora.’ b. Son père et mère, maintenant morts, étaient également normaux. [www.migrations.fr] _their father and mother now dead, were PL_ normal as well_. ‘Their father and mother, now dead, were normal as well.’ Conclusions a) Mismatches between ‘morphological’ and ‘semantic’ number can be captured through the interaction of two different types of phi-features (concord and index phi-features). b) Concord and index features behave as bundles from the syntactic point of view. Syntax is not sensitive to the concord/index difference, only to the featural content of the bundles. c) Agree must be understood as feature sharing and is independent of Case checking/valuation and of ‘activation’ of the Goals. There is no Agree/Concord difference. d) According to our analysis, but not to the ellipsis analysis, the agreement facts explored form a natural class of phenomena with other cases of agreement mismatches: collective nouns (Wechsler & Zlatić 2003: 76-77). References [CREA] Real Academia Española. Banco de datos en línea Corpus de referencia del español actual (CREA). <http://www.rae.es>. Amsterdam/Boston: North Holland Linguistic Series. CARESTENS, V. 2001. Multiple agreement and case deletion. Against phi-(in)completeness. Syntax 4:3; 147-163.
Conferencing is an essential component of any collaboration system, especially when serving remote users and/or a large user base. Cisco Rich Media Conferencing improves on traditional conferencing by offering features such as instant, permanent, and scheduled audio and video conferencing, as well as application sharing. Conference bridges provide the conferencing function. A conference bridge is a resource that joins multiple participants into a single call (audio or video). It can accept any number of connections for a given conference, up to the maximum number of streams allowed for a single conference on that device. The output stream for a given party is the composite of the streams from all connected parties minus their own input stream. To provide a satisfactory end-user experience, careful planning and design should be done when deploying Cisco Rich Media Conferencing so that users are enabled with the conferencing functionality they require. To aid in the Cisco Rich Media Conferencing design, this chapter discusses the following main topics: - **Types of Conferences, page 11-2** This section provides an introduction of the different types of conferences supported throughout the Cisco Rich Media Conferencing Architecture. - **Cisco Rich Media Conferencing Architecture, page 11-4** This section introduces the main components of Cisco Rich Media Conferencing and describes its advantages as well as the different conferencing mechanisms available through the various components of a collaboration system such as Cisco Unified Communications Manager and Cisco TelePresence Video Communication Server. Supported deployment models, solutions and recommendations are discussed here as well. - **High Availability for Cisco Rich Media Conferencing, page 11-32** This section discusses best practices for designing a resilient Cisco Rich Media Conferencing solution; it also contains guidance for redundancy and load balancing. - **Capacity Planning for Cisco Rich Media Conferencing, page 11-37** This section provides best practices and design information related to capacity limits and scalability for Cisco Rich Media Conferencing. - **Design Considerations for Cisco Rich Media Conferencing, page 11-42** This section discusses general recommendations and best practices for the Cisco Rich Media Conferencing design. What's New in This Chapter This chapter has been updated with new support and updated designs for Cisco Collaboration System Release 10.6. You should read this entire chapter before deploying Rich Media Conferencing in your Cisco Collaboration System. Table 11-1 lists the topics that are new in this chapter or that have changed significantly from previous releases of this document. ### Table 11-1 New or Changed Information Since the Previous Release of This Document <table> <thead> <tr> <th>New or Revised Topic</th> <th>Described in:</th> <th>Revision Date</th> </tr> </thead> <tbody> <tr> <td>New supported conferencing solutions for Cisco Collaboration System Release 10.6</td> <td>Various sections of this chapter</td> <td>January 15, 2015</td> </tr> <tr> <td>Maximum number of audio streams supported by a software conference bridge</td> <td>Software Audio Conference Bridge, page 11-25</td> <td>August 23, 2013</td> </tr> <tr> <td>Maximum latency between endpoints</td> <td>Latency, page 11-45</td> <td>August 23, 2013</td> </tr> <tr> <td>Minor change for videoconferencing resources</td> <td>Video Conferencing, page 11-16</td> <td>June 28, 2013</td> </tr> <tr> <td>This chapter was first added to this document as new content</td> <td>All sections of this chapter</td> <td>April 2, 2013</td> </tr> </tbody> </table> Types of Conferences The Cisco Rich Media Conferencing solution supports the following types of conferences: **Instant Conference** An instant audio or video conference (also referred to as an ad hoc conference) is an impromptu conference. Instant conferences are not scheduled or arranged prior to the conference. For example, a point-to-point call escalated to a multipoint conference is considered to be an instant conference. **Permanent Conference** Permanent conferences (also referred to as meet-me, static, or rendezvous conferences) are predefined addresses that allow conferencing without previous scheduling. The conference host shares the address with other users, who can call in to that address at any time. Permanent conference resources are used on a first-come-first-served basis (non-assured). For a guaranteed conference resource (assured), scheduled conferences should be used. (See Scheduled Conference, page 11-2.) **Scheduled Conference** A scheduled conference is started by its initiator through a scheduling management system called Cisco TelePresence Management Suite (TMS). Conferences are booked via Cisco TMS with a start and end time and optionally with a predefined set of participants. **Cisco Collaboration Meeting Room (CMR)** Cisco Collaboration Meeting Room (CMR) is similar to a permanent conference, but it is provisioned from a Cisco TMS portal, which allows users to manage items such as their conference name, layouts, and PIN. Cisco CMR Hybrid (formerly, WebEx Enabled TelePresence) Cisco CMR Hybrid is similar to scheduled conferencing, but with a link to Cisco WebEx Meeting Center, which allows TelePresence and WebEx participants to join the same meeting and share voice, video, and content. Cisco CMR Cloud Cisco CMR Cloud is an alternate conferencing deployment model that does not require any on-premises conferencing resources or management infrastructure. It supports both scheduled and non-scheduled meetings as well as TelePresence, audio, and WebEx participants in a single call, all hosted in the cloud. Personal Multiparty Personal Multiparty conferencing involves a user-based licensing approach that provides instant, permanent, and CMR conferences that a named host (entitled user) may use. Two variations of this licensing model exist, Basic and Advanced. While the conference types are similar to those mentioned above, they use dedicated TelePresence Servers managed by TelePresence Conductor because the licenses for Personal Multiparty conferencing may not be shared with other conference types. TelePresence Servers licensed with Personal Multiparty do not require screen licenses to be purchased, although licenses received through Personal Multiparty licensing must still be applied to the devices. Cisco Personal Multiparty Basic: - Includes a named host, four-party license for multiparty video and audio with content sharing - Supports video resolution up to 720p at 30 frames per second (fps) and content resolution up to 720p at 5 fps - Easily adds participants during a meeting - Includes a personal conference address for every host - Enabled by Cisco TelePresence Server and TelePresence Conductor - Supports single screen endpoints Personal Multiparty Advanced (in addition to the above capabilities): - Provides meeting scheduling capability - Supports an unrestricted number of participants in a meeting (within the limits of the fair use policy) - Supports video and content resolution up to 1080p at 30 fps - Supports Microsoft Lync and business-to-business interoperability with Cisco Expressway Rich Media Session (RMS) licenses - Supports multi-screen endpoints Cisco WebEx Meetings Server Where cloud-based web and audio conferencing is not suitable, it is possible to use the on-premises WebEx Meetings Server solution. This product offers a standalone audio, video, and collaboration web conferencing platform. Cisco Rich Media Conferencing Architecture The Cisco conferencing architecture enables rich conferencing collaboration capabilities for endpoints registered to Cisco Unified Communications Manager (Unified CM) as well as the ability to integrate business-to-business audio and video systems and legacy H.323 video systems interworked from Cisco Expressway to Unified CM. This architecture provides a rich feature set by relying on a variety of components in the conferencing solution. The following sections present an overview of those components and their roles in the Cisco rich media conferencing solutions. Role of Cisco TelePresence Conductor Cisco TelePresence Conductor manages the bridge resources for permanent and instant conferences and, as of Cisco Collaboration System Release (CSR) 10.6, can even manage scheduled conferencing resources. TelePresence Conductor selects which bridge or bridge pools to use to host a specific conference, and it balances the conference load across the bridges in the defined pools. Unified CM is unaware of the individual bridges in the network and communicates only with the TelePresence Conductor. Using TelePresence Conductor for conferences has several benefits, including: - Increased efficiency by allowing instant, permanent, and CMR conferences as well as scheduled conferences to use the same TelePresence Servers - Better user experience through advanced TelePresence Server features such as ActiveControl and dynamic optimization of resources - Simpler deployment options through provisioned CMRs - Centralized management of scheduled resources - Increased scalability of a rich media conferencing solution In certain cases TelePresence Conductor optimizes TelePresence Server resources dynamically when the Optimize resources setting is enabled in the TelePresence Conductor conference template. This enforces maximum resource usage of a participant based on the maximum receive bandwidth advertised by the resources at conference join. This can reduce the amount of resources conference calls use and allows more concurrent connections to take place. For more information, see the TelePresence Server release notes available at Role of the TelePresence Server Cisco TelePresence Server is a scalable videoconferencing bridge that offers flexible video, audio, and content-sharing capabilities for multiparty videoconferencing. It allows users to easily create, launch, and join meetings using standards-based video endpoints, mobile devices, Cisco WebEx clients, and third-party video endpoints. It works in conjunction with Cisco TelePresence Conductor to offer flexible, cost-efficient conferencing. Its benefits include: - A consistent user experience across mobile, desktop, or room-based videoconferencing solutions - Flexible layouts, and views optimized for the capabilities of each device - Enhanced user experience with features including Cisco TelePresence ActivePresence screen layout, individual participant identifiers, and Cisco ClearPath - The ability to extend scale and reach to more participants to join meetings by extending meetings to WebEx Meeting Center users Cisco TelePresence Server is available as a virtualized application compatible with standard Cisco Unified Computing System (UCS) servers, or you can deploy it on dedicated hardware platforms. Flexible licensing options are offered to enable you to deploy Cisco TelePresence Server capabilities in the way that best suits your needs. You can license Cisco TelePresence Server in conjunction with Cisco TelePresence Conductor on a per-user basis for high-quality small group instant conferencing, with Cisco Personal Multiparty licensing, or on a concurrent call (screen) basis to enable the whole enterprise without restrictions. Role of Cisco TelePresence Management Suite (TMS) Cisco TMS provides scheduling, control, and management of Cisco TelePresence conferencing and media services infrastructure and endpoints. Cisco TMS integrates and searches directories and external information sources. It also coordinates with third-party calendars such as Microsoft Outlook so that users of those systems can book Cisco TelePresence and CMR Hybrid meetings. Cisco TMS also includes ready-to-run reports that provide enhanced TelePresence reporting and actionable insight for administrators. The TelePresence Management Suite is a software application that installs on a customer-supplied server supporting medium to large networks. At least 2,000 systems are supported; this includes endpoints, Cisco Unified CM, Cisco Video Communication Servers (VCSs), Multipoint Control Units (MCUs), and other infrastructure components. The TelePresence Management Suite makes video services available to both administrators and conference organizers to schedule endpoints by using the following tools: - TelePresence Management Suite user interface — Provides complete control and advanced settings and is typically used by administrators. - TelePresence Management Suite Scheduler web application — Uses wizards to schedule conferences, add systems, and view availability. It is typically used by conference organizers. - Cisco TelePresence Management Suite Extension for Microsoft Exchange (TMSXE) — TMEXE is an extension of TMS that enables Cisco TelePresence scheduling through Microsoft Outlook. It does this by replicating Cisco TMS scheduled meetings to Microsoft Exchange room calendars. This extension enables conference organizers to set up conferences using their Microsoft Outlook client. - Cisco TelePresence Management Suite Extension for IBM Lotus Notes (TMSXN) — This extension enables conference organizers to set up conferences using their Lotus Notes client. Cisco Rich Media Conferencing Architecture Chapter 11 Cisco Rich Media Conferencing - Cisco TelePresence Management Suite Extension Booking API (TMSBA) — This extension gives developers access to TMS booking functionality for custom integration with third-party calendaring applications. This enables conference organizers to set up conferences using their existing corporate calendaring interface. - Cisco TelePresence Management Suite Provisioning Extension (TMSPE) — TMSPE is an extension for TMS that enables rapid provisioning of TelePresence users, endpoints, and Collaboration Meeting Rooms (CMRs) for large-scale deployments. In conjunction with Cisco TelePresence Conductor, Cisco TMSPE allows for automatic importing of users and creation of their permanent CMRs. It also hosts a Self-Care Portal user self-service, allowing users to create and configure their personal CMRs. TMSXE, TMSXN, and TMSBA are optional plug-ins installed on the calendaring server to achieve calendar integration. Client machines do not have to be modified. Conference Bridges for Non-Scheduled Conferences For permanent and instant conferences, administrators group TelePresence Servers into pools in TelePresence Conductor, and TelePresence Conductor applies service preferences to prioritize the use of the pools for specific conference calls. These bridges are referred to as General TelePresence Server in the figures. TelePresence Server bridges must operate in remotely managed mode. The TelePresence Server on Cisco Multiparty Media 310 or 320, and Cisco TelePresence Server on Virtual Machine, always operate in this mode. Conference Bridges for Scheduled Conferences Scheduled conferences, including CMR Hybrid meetings for participation by Cisco WebEx users, are supported on Cisco TelePresence Server 7010 and MSE 8710 conference bridges. The bridges may be connected directly to Unified CM or through TelePresence Conductor. Figure 11-1 shows two dedicated TelePresence Servers used for scheduled and Cisco WebEx conferences, where scheduling bridges are connected via SIP to TelePresence Conductor and Unified CM engages TelePresence Conductor via SIP to establish the video conferences. Figure 11-1 illustrates a design where TelePresence Conductor manages both scheduled and non-scheduled conference bridges. This is a newly supported design in Cisco Collaboration System Release (CSR) 10.6. In this architecture, scheduled conferences can be dedicated for scheduling as indicated in Figure 11-2 or, as indicated in Figure 11-3, shared (not dedicated) with a pool of TelePresence Servers (General TelePresence Server in the illustration) that are grouped together and used on a first-come-first-served basis by TelePresence Conductor for instant, permanent, and scheduled conferencing (see Deployment Considerations, page 11-11, for more information). Figure 11-2 shows multiple shared TelePresence Servers used for both scheduled and non-scheduled conferences as well as Cisco WebEx conferences. In this design, scheduling bridges are connected via SIP to TelePresence Conductor, and Unified CM engages TelePresence Conductor directly via SIP to establish the video conferences. Figure 11-2 Scheduling with TelePresence Conductor and Shared Resources Figure 11-3 shows two dedicated TelePresence Servers used for scheduled and Cisco WebEx conferences, where scheduling bridges are directly connected via SIP to Unified CM. This is a legacy design and was supported prior to Collaboration System Release 10.6. Figure 11-3 Scheduling without TelePresence Conductor Figure 11-3 illustrates a design where TelePresence Conductor manages the non-scheduled bridges for instant and permanent (General TelePresence Server) conferencing while the scheduled bridges (Scheduled TelePresence Server) are directly connected to Unified CM via SIP. SIP trunks are used for call control between the General TelePresence Server bridges and the TelePresence Conductor, between the Scheduled TelePresence Server bridges and the Unified CM, and between the TelePresence Conductor and Unified CM. XML-RPC (Remote Procedure Call) over HTTPs is used as an application programming interface (API) for resource control as well as provisioning and management. Cisco TMS also uses XML-RPC over HTTPs to link to the TelePresence Conductor for provisioning and directly to the TelePresence Servers for scheduled conference management as well as connecting to Unified CM for endpoint discovery and resource booking. Scheduled resources such as the Cisco TelePresence Server 7010 and MSE 8710 bridges are directly connected to Unified CM and TMS and must be configured in locally managed mode. Scheduled conferencing is not supported on the TelePresence Server on Multiparty Media 310 or 320, nor on the Cisco TelePresence Server on Virtual Machine, because they cannot operate in this mode. A number of different designs can be implemented, depending on the conferencing requirements of the desired solution. Some of those requirements include: - Audio-only versus video conferencing - Scheduled versus non-scheduled conferencing - Resource availability – dedicated versus shared **Audio-Only Versus Video Conferencing** For audio-only conferencing, Cisco recommends using Unified CM as the conferencing manager and using hardware conference bridges on the Cisco Integrated Services Router. See Audio Conferencing, page 11-14, for further details. For video conferencing, Cisco recommends using TelePresence Conductor for centralized management of the video conferencing solution with TelePresence Server as the conferencing bridge of choice for both audio-only and video conferencing, and any combination thereof achieved through screen licenses. For more information about screen licenses per call type, that cover audio-only licensing, refer to the Cisco TelePresence Server Data Sheet available at Scheduled Versus Non-Scheduled Conferencing Scheduled conferencing utilizes a scheduling management system such as Cisco TelePresence Management Suite (TMS). Conferences are booked via Cisco TMS with a start and end time, and optionally with a predefined set of participants. TMS can be utilized for scheduling in either of the following two distinct designs. **TMS Scheduling without TelePresence Conductor** In this first design, the solution supports scheduling of conferences on TMS with bridges directly engaged by Unified CM rather than via the TelePresence Conductor. Scheduling is performed with Cisco TMS, using Microsoft Outlook, through Cisco TelePresence Management Suite Extension for Microsoft Exchange (TMSXE). Scheduled conferences, including CMR Hybrid meetings for participation by Cisco WebEx users, are supported on Cisco TelePresence Server 7010 and MSE 8710 conference bridges. The bridges must be connected directly to Unified CM and not through TelePresence Conductor, and configured in *locally managed mode*. Figure 11-4 shows two dedicated TelePresence Servers used for scheduled and Cisco WebEx conferences for CMR Hybrid. A SIP trunk is configured directly between the TelePresence Servers and Unified CM to enable Unified CM to engage the bridge resources in the scheduled conferencing call flows. Figure 11-4 TMS Scheduling without TelePresence Conductor TMS Scheduling with TelePresence Conductor In this second design, the solution supports scheduling on TMS with conferencing bridges engaged by the TelePresence Conductor. Scheduling is performed with Cisco TMS, using Microsoft Outlook, through TMSXE. Scheduled conferences, including CMR Hybrid meetings for participation by Cisco WebEx users, are supported on Cisco TelePresence Server 7010 and MSE 8710 conference bridges. The bridges must be connected directly to TelePresence Conductor and in remotely managed mode. Figure 11-5 shows two dedicated TelePresence Servers used for scheduled and Cisco WebEx conferences connected to and managed by TelePresence Conductor. A SIP trunk is configured between Unified CM and TelePresence Conductor, and between TelePresence Conductor and the TelePresence Servers. In these scheduled conferencing call flows, Unified CM communicates directly with TelePresence Conductor to request the conferencing resources. Deployment Considerations The physical location of a TelePresence Server is important to consider because media traffic flows between it and each participant in the conference. To provide the best experience for participants, centralize the location of the TelePresence Servers in each region where they will be deployed. Figure 11-6 illustrates the deployment differences between remotely and locally managed modes. Set the TelePresence Servers to remotely managed mode, which is a system-wide setting that enables a more advanced API and requires that API to be used for all operations. Remotely managed mode is the only mode available on the Cisco TelePresence Server on Virtual Machine and Cisco TelePresence Server on Multiparty Media 310 or 320, while other variants of the TelePresence Server have a locally managed mode that cannot be used with TelePresence Conductor. Caution In remotely managed mode, certain features are not available from the TelePresence Server interface, and management of conferences and pre-configuration of endpoints are done at the TelePresence Conductor level instead. Changing the operating mode requires the TelePresence Server to be rebooted, and any conferences configured on the TelePresence Server in locally managed mode are lost when the unit reboots. The TelePresence Server has the ability to use a secure connection for communications. These security features are enabled with the encryption feature key. The encryption feature key is required for TelePresence Conductor to communicate with the TelePresence Server; unencrypted communication is not supported. Interworking H.323 Endpoints into a SIP Environment Many designs require the ability to incorporate H.323 endpoints into the architecture and to ensure interworking with a SIP-based design. The Cisco Video Communication Server (VCS) can be used to interwork these H.323 endpoints into a SIP-based design to provide features such as H.323-to-SIP conversion for call control, H.239-to-BFCP conversion for presentation sharing, and H.235-to-SIP for SRTP conversion. Figure 11-7 illustrates a conferencing design with VCS interworking the H.323 endpoints with SIP to Unified CM to access the SIP-based rich media conferencing solution. Figure 11-7 Architecture Overview for H.323 Interworking Design Considerations for Audio and Video Conferencing The following sections provide general information and an explanation about the resources used in the conferencing architecture, as well as best practices for the conference types that use those resources. - Audio Conferencing, page 11-14 - Video Conferencing, page 11-16 - Conferencing Resources, page 11-24 Audio Conferencing If you are deploying a large-scale video conferencing solution, Cisco recommends also deploying audio conferencing as part of that solution. The video conferencing solution requires TelePresence Conductor and TelePresence Server, which can also be used for audio conferencing. This reduces the complexity and total cost of ownership of the overall conferencing solution. Note TelePresence Server does not support any advanced audio bridge functionality such as join or leave tones, or any form of in-meeting control. If you are deploying an audio-only conferencing solution, Cisco recommends using Unified CM to manage the conferencing resources. It is important to note that a video multipoint resource can be used for audio-only conferences, but audio-only conferencing resources cannot be used for the audio portion of video conferences. Audio conferencing can be performed by both software-based and hardware-based conferencing resources. A hardware conference bridge has all the capabilities of a software conference bridge. In addition, some hardware conference bridges can support multiple low bit-rate (LBR) stream types such as G.729 or G.723. This capability enables some hardware conference bridges to handle mixed-mode conferences. In a mixed-mode conference, the hardware conference bridge transcodes G.729 and G.723 streams into G.711 streams, mixes them, and then encodes the resulting stream into the appropriate stream type for transmission back to the user. Some hardware conference bridges support only G.711 conferences. All voice conference bridges that are under the control of Cisco Unified Communications Manager (Unified CM) use Skinny Client Control Protocol (SCCP) to communicate with Unified CM. Unified CM allocates a conference bridge from a conferencing resource that is registered with the Unified CM cluster. Both hardware and software conferencing resources can register with Unified CM at the same time, and Unified CM can allocate and use conference bridges from either resource. Unified CM does not distinguish between these types of conference bridges when it processes a conference allocation request. The number of individual conferences that can be supported by the resource varies, and the maximum number of participants in a single conference also varies, depending on the resource. Although Cisco Unified CM supports a wide variety of conference bridges, Cisco recommends the following hardware conference bridge resources over legacy conference bridges for Unified CM audio conferencing: Cisco NM-HDV2, NM-HD-1V/2V/2VE, PVDM2, and PVDM3 DSPs. **Instant Audio Conference** This type of conference can be created by a user invoking the Conf function of the Cisco Collaboration endpoint. Cisco Unified CM supports integration of hardware conference bridges for this kind of audio conference. The conference bridge needs to be defined as a media resource in Unified CM for it to be available during the bridge selection process. Only the following event invokes instant conference bridge resources: The user of an SCCP or SIP endpoint presses the Conf, Join, or cBarge softkey to invoke an instant conference. Participants in this type of conference can include any type of endpoint (that is, video and non-video devices using any signaling protocol that Unified CM supports via any supported gateway type); however, only Cisco Collaboration endpoints or clients that have available the Cisco Unified CM Conf key functionality can initiate the instant conference. In other words, an H.323 video endpoint cannot initiate an instant audio conference resource, but a video-enabled Cisco Unified IP Phone 9971 can invoke the conferencing resource and then join an H.323 video participant to the call. For example, the user at the Unified IP Phone 9971 could press the Conf key, dial the directory number of an H.323 client, and then press the Conf key again to complete the transaction. The H.323 client in this case would be joined as a participant on the instant audio conference. **Meet-Me Audio Conference** A meet-me audio conference is a permanent conference type. For meet-me audio conferencing, the conference initiator creates the conference ahead of time by invoking the MeetMe function of the Cisco Collaboration endpoint. The conference initiator then distributes the MeetMe number to the attendees so they can dial in. The conference bridge needs to be defined as a media resource in Cisco Unified CM and must be available to the conference initiator for the meet-me audio conference to be possible. **Scheduled Audio Conference** Traditionally, audio conferencing is created through instant or permanent methods; however, scheduling for audio conferences is also available through the integration of Cisco Collaborative Conferencing. For further information, see Cisco Collaboration Services, page 22-1. **Security in Audio Conferences** Secure conferencing is a way to use regular conferencing to ensure that the media for the conference is secure and cannot be compromised. There are various security levels that a conference can have, such as authenticated or encrypted. With secure conferencing, the devices and conferencing resources can be authenticated to be trusted devices, and the conference media can then be encrypted so that every authenticated participant sends and receives encrypted media for that conference. In most cases the security level of the conference depends on the lowest security level of the participants in the conference. For example, if there is one participant who is not using a secure endpoint, then the entire conference will be non-secure. As another example, if one of the endpoints is authenticated but does not do encryption, then the conference will be in authenticated mode. Secure conferencing provides conferencing functionality at an enhanced security level and prevents unauthorized capture and decryption of conference calls. Consider the following factors when designing secure conferencing: - Security levels of devices (phones and conferencing resources) - Bandwidth overhead for call signaling and secure (SRTP) media - Bandwidth utilization impact if secure participants are across the WAN - Any intermediate devices such as NAT and firewalls that might not support secure calls across them Secure conferencing is subject to the following restrictions and limitations: - Secure conferencing can use more DSP resources than non-secure conferencing, so DSPs must be provisioned according to the DSP Calculator. For further information, see the section on Sizing the Conferencing Resources, page 11-38. - Some protocols might rely on IPSec to secure the call signaling. - Secure conferencing cannot be cascaded between Unified CM and Unified CM Express. - Media termination points (MTPs) and transcoders do not support secure calls. Therefore, a conference might no longer be secure if any call into that conference invokes an MTP or a transcoder. - An elaborate security policy set in place by the IT staff for equipment usage might be needed. - Secure conferencing might not be available for all codecs. The number of individual conferences that can be supported by the resource varies, and the maximum number of participants in a single conference also varies, depending on the resource. **Video Conferencing** When integrated with the Cisco Rich Media Conferencing architecture, video-capable endpoints provide the capability to conduct video conferences that function similar to audio conferences. Video conferences can be instant, permanent, or scheduled. This section discusses the following main topics: - Meeting Experience, page 11-17 - Instant Video Conferences, page 11-18 - Permanent Video Conferences, page 11-20 - Scheduled Video Conferences, page 11-22 Videoconferencing resources are hardware or software types, and currently the main difference between software and hardware video resources is capacity: - Software videoconferencing bridges Software videoconferencing bridges process video and audio for the conference using just software. - Hardware videoconferencing bridges Hardware videoconferencing bridges have hardware DSPs that are used for the video conferences. The Cisco TelePresence MSE 8000 Series, Cisco TelePresence MCU 5300 Series, Cisco TelePresence Server, and in the case of Cisco Unified CM, the PVDM3 DSPs (with Cisco IOS Release 15.1.4M and later releases) provide this type of videoconferencing bridge. Most hardware videoconferencing bridges can also be used as audio-only conference bridges. Hardware videoconferencing bridges provide the advantage of more capacity than software videoconferencing bridges. Meeting Experience The video portion of the conference can operate in one of three meeting experience modes, depending on the conferencing device: - Full-Screen Voice Activation, page 11-17, (TelePresence Server or MCU) - Continuous Presence, page 11-17, (TelePresence Server or MCU) - Cisco ActivePresence, page 11-17, (TelePresence Server) In addition, video conferencing can use any of the following methods to select the dominant speaker: - Voice Activation Mode, page 11-18 - Manual Selection of the Dominant Speaker, page 11-18 - Automatic Participant List Cycling, page 11-18, (Not available for Cisco TelePresence Server) Full-Screen Voice Activation Voice-activated conferences take in the audio and video streams of all the participants, decide which participant is the dominant speaker, and send only the dominant speaker’s video stream back out to all other participants. The participants then see a full-screen image of the dominant speaker (and the current speaker sees the previous dominant speaker). The audio streams from the participants (four in the case of the Cisco TelePresence MCU and Cisco TelePresence Server) are mixed together, so everyone hears everyone else, but only the dominant speaker’s video is displayed. This mode is optimal when one participant speaks most of the time, as with an instructor teaching or training a group. Speaker (segment) switching and room switching fall under this category. Continuous Presence Continuous-presence conferences display some or all of the participants together in a composite view. The view can display the participants in a variety of layouts. Each layout offers the ability to make one of the squares voice-activated, which is useful if there are more participants in the conference than there are squares to display them all in the composite view. For instance, if you are using a four-way view but there are five participants in the call, only four of them will be displayed at any given time. You can make one of the squares in this case voice-activated so that participants 5 and 6 will switch in and out of that square, depending on who is the dominant speaker. The participants displayed in the other three squares would be fixed, and all of the squares can be manipulated through the conference control web-based user interface, DTMF (in the case of the Cisco TelePresence MCU and Cisco TelePresence Server), and Far End Camera Control (FECC, in the case of the Cisco TelePresence Server). On the other hand, if you are using the "equal panels layout family," the layout would change to 3x3 when the sixth participant joins. The audio portion of the conference follows or tracks the dominant speaker. Continuous presence is more popular than voice switching, and it is optimal for conferences or discussions between speakers at various sites. Cisco ActivePresence The Cisco ActivePresence capability of Cisco TelePresence Server, a leading patent-pending feature, enables the delivery of next-generation multipoint conferencing by offering a view of all attendees in a meeting while giving prominence to the active speaker. While the active speaker occupies most of the screen, an overlay of others in the call appears in the lower third of the screen. This maintains the immersive feel of the life-size main speakers while giving participants a more natural view of everyone else sitting around the virtual table. Voice Activation Mode Using this mode, the video conference bridge automatically selects the dominant speaker by determining which conference participant is speaking the loudest and the longest. To determine loudness, the MCU calculates the strength of the voice signal for each participant. As conditions change throughout the conversation, the MCU automatically selects a new dominant speaker and switches the video to display that participant. A hold timer prevents the video from switching too hastily. To become the dominant speaker, a participant has to speak for a specified number of seconds and be more dominant than all other participants. Manual Selection of the Dominant Speaker The dominant speaker might be selected through the MCU’s web-based conference control user interface. A user with privileges to log onto the MCU’s web page, highlights a participant and selects that person as the important or dominant speaker. This action disables voice activity detection, and the dominant speaker remains constant until the chairperson either selects a new dominant speaker or re-enables voice activation mode. Automatic Participant List Cycling With this method, the MCU is configured to cycle through the participant list automatically, one participant at a time. The MCU stays on each participant for a configured period of time and then switches to the next participant in the list. The conference controller (or chairperson) can turn this feature on and off (re-enable voice activation mode) from the web interface. Instant Video Conferences Instant video conferences can be accomplished using embedded video resources (MultiSite) or dedicated video resources. The method for initiating an instant conference varies according to the call control used to initiate it. Cisco Collaboration endpoints managed by Cisco Unified CM can initiate the conference through the use of Conf, Join, or cBarge keys or the Add function (for endpoints with the MultiSite functionality), endpoints managed by Cisco VCS can initiate the conference by making use of Multiway or MultiSite functionality. This section discusses how instant conferences occur with embedded and dedicated resources. Note For H.323 and SIP clients with built-in MCUs, Unified CM allows functionality of the endpoint’s built-in MCU only if the client is SIP. MultiSite™ Certain endpoints are capable of escalating point-to-point calls with two endpoints to conferences with three or more endpoints, without the need for an external dedicated device. In Cisco Rich Media Conferencing this ability is referred to as MultiSite™. The conference created using MultiSite is considered instant because it usually happens without prior planning and scheduling (see Figure 11-8). An option key is required to unlock the MultiSite feature. MultiSite conferences use the embedded resources in the endpoint for the conference creation. Endpoints with MultiSite capability that have the key installed can invoke this conference type whether they are managed by Cisco Unified CM or Cisco VCS. Instant Conferences Using Dedicated Devices While many video endpoints on the market today are incapable of hosting conferences themselves and require an additional device to handle mixing the multiple video and audio streams, key factors for selecting dedicated video resources over embedded resources are bandwidth usage centralization, scalability, and cost efficiency. These multipoint resources are shared by a number of endpoints and are capable of hosting many conferences at the same time. The method in which a dedicated resource is invoked depends on the endpoints and the call control device(s) involved. In the case of users utilizing devices that can and are registered natively to Cisco Unified CM, the users can initiate an instant video conference with dedicated resources by using the Conf, Join, or cBarge keys. Figure 11-9 illustrates one example of an instant conference using an external resource. Currently the MCU and Cisco TelePresence Server (when used in conjunction with Cisco TelePresence Conductor) are the only dedicated resources that enable instant calls for TelePresence endpoints controlled by Cisco VCS. The Cisco PVDM3 module can be added to this list for endpoints controlled by Cisco Unified CM. **Permanent Video Conferences** Permanent conferences can be initiated in three different ways depending on the call control used by the conference initiator. Cisco Unified CM supports video meet-me, MCU-IVR dial-in, and preconfigured permanent alias video conference initiation methods. Figure 11-10 depicts an example of a permanent conference taking place. The main differences between video meet-me conferences and preconfigured permanent alias video conferences is the launch method. The user initiates a meet-me conference through a softkey, while the permanent alias for a video conference is always available after it has been preconfigured by the administrator and the user needs to dial the alias to join the conference. The Cisco TelePresence multipoint devices may use different names for permanent conferences, referring to them as permanent conferences or static conferences. **IVR for Dial-in Conference** Dial-in conferences can optionally use an interactive voice response (IVR) system to prompt users to enter the conference ID and the password (if one is configured) of the conference they want to join. You can use either of the following types of IVRs with the Cisco MCUs: - The IVR built into the MCU - Cisco Unified IP IVR The built-in IVR of the MCU has the following characteristics: - Can prompt to create a conference or join by conference ID - Can prompt for the password of the conference - Supports both in-band and out-of-band (H.245 alphanumeric) DTMF - Cannot be customized to provide more flexible menus or functionality The only items that the user can customize are the recorded audio file that is played to the user and the logo at the top of the screen. If you want to have a single dial-in number and then prompt the user for the conference ID, you can use Cisco Unified IP IVR in conjunction with the MCU. Cisco Unified IP IVR has the following characteristics: - Only applicable for Cisco Unified CM integrations - Can prompt for the conference ID and the password (among other things) - Supports only out-of-band DTMF That is, the calling device must support an out-of-band DTMF method (such as H.245 alphanumeric) on H.323 devices. These out-of-band DTMF messages are then relayed by Unified CM to the Cisco IP IVR server. If the calling device supports only in-band DTMF tones, the Cisco IP IVR server will not recognize them and the calling device will be unable to enter the conference. - Can be highly customized to provide more flexible menus and other advanced functionality Customizations can include such things as verifying the user’s account against a back-end database before permitting that user to enter into the conference, or queuing the participants until the chairperson joins. **Note** Because Cisco Unified IP IVR supports only out-of-band signaling, it will not work with endpoints that use in-band DTMF tones. With Cisco Unified IP IVR, users dial a CTI route point that routes the call to the Cisco Unified IP IVR server instead of dialing a route pattern that routes directly to the MCU. After collecting the DTMF digits of the conference ID, the Cisco Unified IP IVR then transfers the call to the route pattern that routes the call to the MCU. This transfer operation requires that the calling device supports having its media channels closed and reopened to a new destination. For example, an H.323 video device that calls the Cisco Unified IP IVR will initially negotiate an audio channel to the Cisco Unified IP IVR server and then, after entering the appropriate DTMF digits, it will be transferred to the MCU, at which point Unified CM will invoke the Empty Capabilities Set (ECS) procedure to close the audio channel between the endpoint and the Cisco Unified IP IVR server and open new logical channels between the endpoint and the MCU. If the H.323 video endpoint does not support receiving an ECS from Unified CM, it will react by misbehaving or disconnecting the call. **Scheduled Video Conferences** Cisco Unified CM 10.5.2 and later releases, TelePresence Conductor 3.0, TelePresence Server 4.1, Expressway X8.5, and TelePresence Management Suite (TMS) 14.6 support SIP MCUs for scheduled video conferences. Because SIP is the protocol of choice in Unified CM, Cisco recommends registering any H.323 MCUs to a Cisco TelePresence Video Communication Server (VCS) as a gatekeeper, and configuring H.323-SIP interworking from the VCS to Unified CM to provide support for scheduled video conferences when only H.323 MCUs are available in the infrastructure. Scheduled video conferences provide users with a guarantee that multipoint resources will be available at the conference start time. Scheduled conferences can be joined in a variety of ways, as Table 11-2 describes. Scheduling ensures endpoint and port resource availability and provides convenient methods to connect to TelePresence conferences. Most organizations already use calendaring applications to schedule conferences. In this case, calendaring integration enables users to schedule conferences with their existing calendaring client. TelePresence deployments often include a large quantity of endpoints and different infrastructure components. Without a centralized management component, provisioning, monitoring, and resource allocation are difficult if not impossible. Management platforms greatly simplify these processes. The Cisco TelePresence scheduling and management options you choose depend on the type of calendaring your organization uses, the type of TelePresence deployment selected or already implemented by your organization, and the requirements or preferences of your organization. Scheduled meetings work by integrating TelePresence resources and endpoints with corporate calendaring applications (see Figure 11-11). Cisco TelePresence Management Suite (TMS) resides between endpoints and calendaring applications to locate the proper multipoint resource for each scheduled conference, and to provide resource reservation. Both the TelePresence Server and the MCU are capable of creating scheduled conferences without the aid of the TelePresence Management Suite or TelePresence Manager; however, in this case only the multipoint device is scheduled, but the endpoints themselves are not guaranteed to be available. For this reason Cisco recommends deploying scheduled conferencing with the TelePresence Management Suite and creating conferences by scheduling three or more endpoints. <table> <thead> <tr> <th>Launch Method</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td>One Button to Push (OBTP)</td> <td>Conference dial-in information is automatically displayed on endpoints that support OBTP. For systems that do not support OBTP, an email with conference information is sent to the conference owner to forward to the participants.</td> </tr> <tr> <td>Automatic Connect</td> <td>All endpoints are automatically connected at the specified date and time.</td> </tr> <tr> <td>Manual Connect or Hosted</td> <td>Conference cannot begin until a specific endpoint (usually the conference organizer’s endpoint) connects. After this endpoint connects, the remaining endpoints are either automatically connected or allowed to dial in manually.</td> </tr> <tr> <td>No Connect</td> <td>For conferences managed by the Cisco TelePresence Management Suite (TMS), this option only reserves the endpoints and MCU ports. The conference can be started by clicking Connect for the participants in TMS Conference Control Center.</td> </tr> <tr> <td>Reservation</td> <td>Reserves the endpoints but does not initiate any connections.</td> </tr> </tbody> </table> Security in Video Conferences Unified CM supports secure conferencing with SIP MCU integration types. With secure conferencing, Unified CM uses HTTPS to communicate to the MCU for conference scheduling, it uses TLS for call signaling, and it uses SRTP for media payload encryption. However, the conference is secure only if all the participants’ endpoints support video encryption. Alternatively, Cisco VCS supports secure conferencing in environments with H.323 and SIP MCUs. Cisco VCS can also offer security interworking between H.235 and SRTP, thus making it better suited for deployments in which security is used with SIP and H.323 protocols. For more information about secure conferencing, see the chapter on Cisco Collaboration Security, page 4-1. Conferencing Resources A conferencing resource is the hardware-based or software-based entity that performs the media conferencing, multiplexing, or media switching functions for the Cisco Rich Media Conferencing Architecture. This section provides overall guidance on the most appropriate uses of each of the following conferencing resources - Audio Conferencing Resources, page 11-25 - Dedicated Audio Conferencing Resources, page 11-25 Software Audio Conference Bridge, page 11-25 Hardware Audio Conference Bridge, page 11-25 - Embedded Audio Resources (Built-in Bridge), page 11-26 - Video Conferencing Resources, page 11-26 - Dedicated Video Resources, page 11-27 Audio Conferencing Resources As stated earlier, Cisco VCS always invokes a video conference bridge MCU for any type of conference, even if its participants are capable of audio-only conferences. Therefore, the information on audio conferencing resources in this section applies only to Cisco Unified CM audio conferences. The audio conference resources have different purposes depending on whether they are dedicated or embedded. Although some can be used interchangeably under some situations, not all of them can. Dedicated Audio Conferencing Resources A dedicated audio resource is an entity whose sole purpose is conference creation, and it stands apart from the endpoint. Dedicated resources can be either software-based or hardware-based. Software Audio Conference Bridge The software-based audio conference bridges are provided by the IP Voice Media Streaming Application on Unified CM. The application must be enabled on each individual node in a cluster. A software unicast conference bridge is a standard conference mixer that is capable of mixing G.711 audio streams and Cisco Wideband audio streams. Any combination of Wideband or G.711 a-law and mu-law streams may be connected to the same conference. The number of conferences that can be supported on a given configuration depends on the server where the conference bridge software is running and on what other functionality has been enabled for the application. However, 256 is the maximum number of audio streams for this type. With 256 streams, a software conference media resource can handle 256 users in a single conference, or the software conference media resource can handle up to 64 conferencing resources with four users per conference. If the Cisco IP Voice Media Streaming Application service runs on the same server as the Cisco CallManager Service, a software conference should not exceed the maximum limit of 48 participants. The Cisco IP Voice Media Streaming Application is a resource that can also be used for several functions, and the design must consider all functions together (see Cisco IP Voice Media Streaming Application, page 7-4). Since the capabilities of the software audio conference bridge are limited, Cisco recommends using a software audio conference bridge only in centralized deployments or in deployments where the use of a G.711 codec is acceptable for instant and meet-me audio conferencing. It is also important to note that the use of a software audio conference bridge in Unified CM will result in a higher load on the system than otherwise would be present. Hardware Audio Conference Bridge Digital signal processors (DSPs) that are configured through Cisco IOS as conference resources load firmware into the DSPs that are specific to conferencing functionality only, and these DSPs cannot be used for any other media feature. Any Cisco PVDM2 or PVDM3 hardware, such as the Cisco NM-HDV2 Network Module, may be used simultaneously in a single chassis for voice termination but may not be used simultaneously for other media resource functionality. The DSPs based on PVDM-256K and PVDM2 have different DSP farm configurations, and only one may be configured in a router at a time. DSPs on PVDM2 hardware are configured individually as voice termination, conferencing, media termination, or transcoding, so that DSPs on a single PVDM may be used as different resource types. Allocate DSPs to voice termination first, then to other functionality as needed. The DSP resources for a conference are reserved during configuration, based on the profile attributes and irrespective of how many participants actually join. Refer to the following module data sheets for accurate information on module capacities and capabilities: - For capacity information on PVDM2 modules, refer to the *High-Density Packet Voice Digital Signal Processor Module for Cisco Unified Communications Solutions* data sheet, available at - For capacity information on PVDM3 modules, refer to the *High-Density Packet Voice Video Digital Signal Processor Module for Cisco Unified Communications Solutions* data sheet, available at Hardware audio conference bridges offer a wider range of capabilities and codec format support than the software conference bridges. Cisco recommends using hardware audio conference bridges where the enterprise requires a more versatile audio conference bridge and codec support for higher-complexity codecs such as G.729 to take advantage of bandwidth savings. ### Embedded Audio Resources (Built-in Bridge) Embedded resources refer to the DSP resources that are hosted by one of the endpoints in the call. Certain Cisco IP Phones have an on-board DSP for the built-in bridge functionality. The IP phone built-in bridge is the only embedded audio resource in the Cisco Rich Media Conferencing architecture. The built-in bridge, however, has limited conference functionality and cannot be used to launch a full conference. The built-in bridge in the Cisco IP Phones allows a user to: - Join calls across different lines that the IP phone might have, and convert those calls into a conference hosted on the built-in bridge - Barge into a call of a different endpoint that shares the line (if the call is not set to private), and convert the call into a conference hosted on the built-in bridge - Start a silent recording or monitoring session from the endpoint that is engaged on a call, and fork the media generated and received by the phone invoking the feature The built-in bridge of the Cisco IP Phones can encode and decode G.711 and G.729 codec formats. However, once the codec for the call has been selected, the built-in bridge codec selection is locked and the phone will be unable to change the codec used. Therefore, the best practice is to carefully analyze the call flow in which the built-in bridge might be invoked to avoid call drops. The built-in bridge can mix a maximum of two calls and can fork only one call (two streams). ### Video Conferencing Resources The actual entity which hosts a multipoint conference may reside within a video endpoint or be separate from the endpoint in a dedicated device whose resources are shared by many endpoints. In many customer environments both options can be deployed. It is also important to understand that the video conferencing functionality is achieved by media transcoding and media switching, refer to the Design and Considerations for Cisco Rich Media Conferencing section of this chapter for further information about the differences of transcoding and switching in video conferencing. Dedicated Video Resources Cisco has a wide range of dedicated devices for audio and video conferencing. The following devices are relevant to Cisco Video Collaboration endpoints: - Cisco TelePresence Server, page 11-27 - Cisco TelePresence Multipoint Control Unit (MCU), page 11-28 - Cisco Packet Voice Digital Signal Processor Module (PVDM3), page 11-29 The dedicated conferencing device mixes the audio and video streams from each video endpoint and transmits a single audio and video stream back to each endpoint. In the case of multi-screen endpoints, multiple audio and video streams may be sent and received by the conferencing device. Using a dedicated device has the following benefits: - Greater scalability - Enhanced feature sets (auto attendants, scheduling, presenter modes, and so forth) - Higher quality user experience - Reduced cost compared to enabling embedded conferencing on large numbers of endpoints Cisco TelePresence Server The Cisco TelePresence Server is a transcoding multipoint device that is available as the Cisco TelePresence Server 7010 appliance or the Cisco TelePresence Server MSE 8710 blade for the Cisco MSE 8000 Series chassis. Cisco TelePresence Server is also supported on virtual machines (Cisco TelePresence Server on Virtual Machine). The TelePresence Server can connect many video and audio devices using a variety of protocols, including SIP, H.323, and TIP. Currently it is the only Cisco multipoint device that supports both TIP and non-TIP multi-screen systems. The TelePresence Server is capable of permanent and scheduled conferences, and it can also support instant conferencing when working in conjunction with Cisco TelePresence Conductor. Cisco recommends using Cisco TelePresence Server for all video conferencing. The Cisco TelePresence Server 7010 and MSE 8710 support the locally managed mode listed in Table 11-3, which in turn affects the supported resolutions and capacity. Table 11-3 also describes the differences between these options. All other versions of Cisco TelePresence Server can be run only in remotely managed mode. <table> <thead> <tr> <th>Mode</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td>Full HD</td> <td>The number of 1080p30 or 720p60 (symmetric) video ports available. This mode allows the TelePresence Server to transmit and receive at these resolutions.</td> </tr> <tr> <td>HD</td> <td>The number of 720p30 or 448p60 (symmetric) video ports available. This mode allows the TelePresence Server to transmit and receive at these resolutions.</td> </tr> </tbody> </table> Cisco TelePresence Multipoint Control Unit (MCU) The Cisco TelePresence Multipoint Control Unit (MCU) portfolio offers flexibility for a variety of video deployments. The MCUs are designed for single-screen Cisco and non-Cisco video endpoints using standards-based H.323 and SIP call signaling. The user’s experience can vary depending upon which of the many custom screen layouts is chosen for a particular conference. The MCU supports instant, permanent, and scheduled conferences. Depending on the model, Cisco MCUs can support resolutions from QCIF up to 1080p in 4:3 and 16:9 aspect ratios and can support the video modes listed in Table 11-4. A global configuration setting on the MCU enables one of these modes, which in turn affects the supported resolutions and capacity. Port count depends on which mode is enabled because HD, HD+, and Full HD settings require more hardware resources than the lower-resolution SD setting. Table 11-4 describes the differences between these options. Table 11-4 MCU Port Mode Options <table> <thead> <tr> <th>Mode</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td>Full HD</td> <td>The number of 1080p30 or 720p60 (symmetric) video ports available. This allows the MCU to transmit and receive at these resolutions.</td> </tr> <tr> <td>HD+</td> <td>The number of 1080p30 or 720p60 (asymmetric) video ports available. This mode allows the MCU only to transmit at these resolutions. This mode is not available for Cisco TelePresence MCU 5300 Series.</td> </tr> <tr> <td>HD</td> <td>The number of 720p30 or w448p60 (symmetric) video ports available. This mode allows the MCU to transmit and receive at these resolutions.</td> </tr> <tr> <td>SD</td> <td>The number of standard definition (up to 448p) symmetric video ports available.</td> </tr> <tr> <td>nHD</td> <td>The number of w360p30 video ports available on Cisco TelePresence MCU MSE 8510 and Cisco TelePresence MCU 5300 Series only.</td> </tr> </tbody> </table> Cisco recommends the using dedicated video resources for greater conference scalability and when a large number of endpoints will be deployed in the organization. Cisco TelePresence MCUs can be pooled together and manage by Cisco TelePresence Conductor for increased flexibility. Feature Comparison When deciding which multipoint device to deploy, it is important not only to understand their audio and video capabilities, but also to know which features are supported on each device. Table 11-5 summarizes feature support for the multipoint devices. Table 11-5 Comparison of Features Across Multipoint Devices <table> <thead> <tr> <th>Feature</th> <th>TelePresence Server</th> <th>MCU</th> <th>Comments</th> </tr> </thead> <tbody> <tr> <td>SIP and H.323 support</td> <td>Yes</td> <td>Yes</td> <td>TelePresence Multipoint Switch uses SIP for initial call setup, but then relies on TIP to negotiate media</td> </tr> <tr> <td>TIP support</td> <td>Yes</td> <td>No</td> <td>Allows multi-screen telepresence immersive endpoints to switch screens intelligently</td> </tr> <tr> <td>WebEx OneTouch 1.x</td> <td>Yes</td> <td>Yes</td> <td>Integration with WebEx allowing one-way video from video endpoints to WebEx cloud, two-way audio, and two-way presentation</td> </tr> <tr> <td>Individual transcoding</td> <td>Yes</td> <td>Yes</td> <td>The ability to support full range of SD and HD resolutions</td> </tr> </tbody> </table> Cisco Packet Voice Digital Signal Processor Module (PVDM3) The Cisco Packet Voice Digital Signal Processor Module PVDM3 is a hardware module that provides digital signal processor (DSP) resources. The PVDM3 is the latest iteration of the DSP conferencing technology available for the Cisco Integrated Service Routers Generation 2 (ISR G2). Cisco has introduced the ability to do multipoint video conferencing for instant and permanent (MeetMe) video conferences with ISR G2 routers and Cisco Unified Communications Manager (Unified CM) when the PVDM3 is used as a media resource. This ability is available only when Cisco Unified CM is used as call control in conjunction with the PVDM3 module and the endpoint supports the native instant conferencing functionality of Unified CM. Table 11-5 Comparison of Features Across Multipoint Devices (continued) <table> <thead> <tr> <th>Feature</th> <th>TelePresence Server</th> <th>MCU</th> <th>Comments</th> </tr> </thead> <tbody> <tr> <td>TelePresence Management Suite scheduling</td> <td>Yes</td> <td>Yes</td> <td>Multipoint device can have conferences created and scheduled via TelePresence Management Suite</td> </tr> <tr> <td>ActivePresence</td> <td>Yes</td> <td>No</td> <td>While MCU does not support ActivePresence, it does have a similar layout (large window for active speaker and smaller PiPs for other endpoints)</td> </tr> <tr> <td>Custom layouts</td> <td>Yes</td> <td>Yes</td> <td>Ability for users to change the experience on their endpoint only during an active meeting</td> </tr> <tr> <td>VIP or Important Mode</td> <td>Yes</td> <td>Yes</td> <td>Ability to designate a particular endpoint as the VIP or Important person and have that person always shown regardless of active speaker</td> </tr> <tr> <td>Director controls</td> <td>No</td> <td>No</td> <td>Allows the mapping and locking of a specific endpoint source to a specific endpoint destination.</td> </tr> <tr> <td>Clustering</td> <td>Yes</td> <td>Yes</td> <td>Clustering on TelePresence Server or MCU requires TelePresence Server MSE 8710 or TelePresence MCU MSE 8510 blades on MSE 8000 Series chassis</td> </tr> <tr> <td>Cascading</td> <td>Yes</td> <td>Yes</td> <td>Ability to combine two separate conferences on two separate devices to increase overall scale</td> </tr> <tr> <td>Lecture Mode</td> <td>No</td> <td>Yes</td> <td>Identifies the &quot;lecturer&quot; based on active speaker. The MCU presents a different layout to the lecturer than the other participants see. The TelePresence Multipoint Switch shows individual audience endpoints to the lecturer full-screen, advancing every few seconds.</td> </tr> <tr> <td>Content sharing</td> <td>Yes</td> <td>Yes</td> <td>TelePresence Multipoint Switch supports only TIP auto-collaborate channel. MCU supports H.323, H.239, and SIP BFCP. TelePresence Server supports all three.</td> </tr> <tr> <td>Auto attendant</td> <td>Yes</td> <td>Yes</td> <td>TelePresence Server and TelePresence Multipoint Switch require this to be enabled on per-meeting basis via scheduling or management device</td> </tr> </tbody> </table> Take into account the following general considerations when using the PVDM3 as a multipoint unit for video conferencing: - It is essential to be familiar with the video capabilities of the video collaboration endpoints in your network. Be aware that heterogeneous conference (video mixing) profiles use significantly more DSP resources than either homogeneous conferences (video switching) or guaranteed audio profiles. If all the phones support the same video format, you should configure a DSP farm profile for a homogeneous conference. - When provisioning the Cisco video collaboration endpoints in the network, configure the endpoints to support a wide range of video capabilities. - You can reduce your DSP resource usage by limiting the video capability class for a heterogeneous video conference. Many endpoints with higher capability can support lower video formats. For example, an H.264 4CIF endpoint can also support H.264 CIF video. Consider configuring your DSP profile to support lower encoder capabilities to optimize your DSP usage. - When you configure a codec resolution in your heterogeneous DSP farm profile, you might have to configure all resolutions explicitly for the same codec. For example, if you have phones that support CIF and other phones that support only VGA, and you want to ensure that phones with either resolution can join the conference, you must explicitly configure both CIF and VGA in the DSP farm profile. This also applies to point-to-point video transcoding DSP farm profiles. For more information about deploying the PVDM3 for video conferencing refer to the following documents: - Configuring Next-Generation High-Density PVDM3 Modules - Video Transcoding and Conferencing Feature configuration guide Cisco recommends using the PVDM3 module for video conferencing only when basic video conferencing support is needed and all the endpoints in the conference controlled by Cisco Unified CM. The PVDM3 module does not offer support for Binary Floor Control Protocol (BFCP) or Far End Camera Control (FECC). **Embedded Video Resources (MultiSite™)** Some endpoints can support embedded video conferencing - the simplest form of video conferencing - in which one video endpoint hosts two or more calls simultaneously. This capability is called MultiSite™ in the Cisco Rich Media Architecture. Additional endpoints connect to the host endpoint, which mixes together the video and audio streams from all the endpoints. Benefits of embedded conferencing include low initial cost and little or no configuration necessary by an administrator. However, some limitations include: - Limited scale. The host endpoint has to mix the audio and video from every other endpoint; therefore, the size of the conference is limited by that host endpoint's capacity. - Endpoints with this capability require more bandwidth than other endpoints. - Depending on the endpoint model, there might be limitations in video resolution, which can degrade the overall user experience when compared to calls hosted on a dedicated multipoint device. For the reasons listed above, Cisco recommends using the MultiSite feature only when limited size instant conferences are needed in the organization. Careful analysis also should be done to weigh the cost benefits of the number of endpoints requiring the MultiSite key versus the benefits of a full MCU. Table 11-6 indicates which devices are capable of MultiSite, and thus of hosting multipoint conferences. <table> <thead> <tr> <th>Endpoint or Codec</th> <th>MultiSite Maximum Resolution</th> <th>Maximum Number of MultiSite Participants (includes host)</th> </tr> </thead> <tbody> <tr> <td>SX20 Codec</td> <td>576p</td> <td>4 video + 1 audio</td> </tr> <tr> <td>SX80 Codec</td> <td>720p, 1080p</td> <td>5 video + 1 audio, 4 video + 1 audio</td> </tr> <tr> <td>C40 Codec</td> <td>576p</td> <td>4 video + 1 audio</td> </tr> <tr> <td>C60 Codec</td> <td>720p</td> <td>4 video + 1 audio</td> </tr> <tr> <td>C90 Codec</td> <td>1080p</td> <td>4 video + 1 audio</td> </tr> <tr> <td>MX200 G2 and MX300 G2</td> <td>576p</td> <td>4 video + 1 audio</td> </tr> <tr> <td>MX700 and MX800</td> <td>720p, 1080p</td> <td>5 video + 1 audio, 4 video + 1 audio</td> </tr> <tr> <td>EX90</td> <td>720p</td> <td>4 video + 1 audio</td> </tr> </tbody> </table> Cisco TelePresence Conductor Cisco TelePresence Conductor works in conjunction with Cisco Unified CM or Cisco VCS to simplify conferencing and the management of multipoint devices. See Role of Cisco TelePresence Conductor, page 11-4, for more information about its role in the Collaboration Solution. TelePresence Conductor is able to manage multiple Cisco MCUs and TelePresence Servers for instant, permanent, and scheduled conferences. TelePresence Conductor can group multipoint resources into pools, thus allowing an administrator to take an individual MCU out of service without impacting service availability. Additionally, unique conference templates can be tailored to meet each user's personal preferences for settings such as participant layouts and PINs. Figure 11-12 and Figure 11-13 illustrate the steps that take place when TelePresence Conductor is used as a conference resource for Unified CM. Figure 11-12 Flow of an Instant Conference Call with Unified CM Once the steps in Figure 11-12 or Figure 11-13 are complete, the call is set up and media flows between the endpoint and the conference bridge. In the case of MCU management, TelePresence Conductor can automatically cascade an active conference to a separate MCU to expand total capacity, and this is transparent to the users. Because of its inherent high availability, Cisco TelePresence Conductor is well suited for organizations where video conferencing resiliency has a premium value and organizations with a large number of multipoint control units. High Availability for Cisco Rich Media Conferencing Proper design of the Cisco Rich Media Conferencing infrastructure requires building a robust and redundant solution from the bottom up. By structuring the solution with redundancy (redundant media resources groups, redundant route groups, Cisco TelePresence Conductor, and redundant media resources), you can build a highly available, fault tolerant, and redundant solution. The following sections provide design guidance for high availability: - Media Resource Groups and Lists, page 11-32 - Route List and Route Groups, page 11-33 - Cisco VCS Conferencing Redundancy, page 11-34 - Redundancy with Cisco TelePresence Conductor, page 11-34 Media Resource Groups and Lists When a user of a Cisco Collaboration endpoint that uses Cisco Unified CM as its call control activates the Conf, Join, or MeetMe softkey, Unified CM uses the Media Resource Manager to select conference bridges. Conference bridges or MCU resources are configured in the media resource groups (MRGs). The media resource group lists (MRGLs) specify a prioritized list of MRGs and can be associated with the endpoints. The Media Resource Manager uses MRGLs of the endpoints for selecting the conference bridge. How you group the resources is completely at your discretion, but Cisco recommends grouping the resources by using a logical modeling of the geographical placement whenever possible so that all endpoints at a given site use the conference bridges closest to them. Cisco Unified CM has the Intelligent Bridge Selection feature, which provides a method for selecting conference resources based on the capabilities of the endpoints in the conference. If there are two or more video endpoints when the conference is initiated and a videoconferencing resource is available, Intelligent Bridge Selection chooses that resource for the conference. On the other hand, if no videoconferencing resource is available or if there are no video-capable endpoints in the conference, Intelligent Bridge Selection chooses an available audio resource for the conference. Intelligent Bridge Selection provides an added functionality to select secure conference bridges for secure conferences. However, secure conference bridge selection is dependent on device capabilities. Unified CM may decide to allocate secure conference bridges in lieu of video or audio conference bridges. Flexibility to change the behavior of the Intelligent Bridge Selection functionality is provided through service parameter configurations in Unified CM. Intelligent Bridge Selection has the following advantages over other methods of conference bridge selection: - Conference bridge selection by conference type - either secure, video, or audio conferences - Simplified media resource configuration - Optimized use of MCU video ports that potentially would have been used for audio-only conferences with other methods of bridge selection All the conference bridge resources and MCUs can be in one MRGL, and Intelligent Bridge Selection will then select the conference bridge based on the need to do just an audio conference or a video conference. Unified CM also supports an alternate way of selecting conference bridges, which can be specified by service parameter configurations. In this mode, Unified CM applies the following criteria to select the conference bridge resource to use, in the order listed here: 1. The priority order in which the media resource groups (MRGs) are listed in the media resource group list (MRGL) 2. Within the selected MRG, the resource that has been used the least If the MCU is placed at the top of the MRGL for the phone, the MCU will always be chosen even for audio-only conferences that do not involve any video-capable participants. In this scenario, the MCU resources might be wasted on audio-only conferences and not be available to satisfy the request for a video conference when it occurs. This mode, however, is not recommended because it removes the intelligence from Unified CM to select the right resource on every conference made and should be used only by administrators who are aware of the system-wide effects of this service parameter setting. For further information about media resource design, see the chapter on Media Resources, page 7-1. Note MeetMe conferences do not use the Intelligent Bridge Selection feature. ### Route List and Route Groups Route lists and route groups are common call routing mechanisms of reliability for calls that leave the Cisco Unified CM domain. For media resources integrated with Cisco Unified CM as a trunk, route lists and route groups should be used to achieve high availability if backup multipoint control units (MCUs) exist. Call admission control can be preserved by setting the locations of the media resources based on the trunk being used for the call. To learn more about Route List and Route Group resiliency mechanisms, see the chapter on Dial Plan, page 14-1. Cisco VCS Conferencing Redundancy To provide redundancy for multipoint conferencing in Cisco VCS, Cisco recommends the use of Cisco TelePresence Conductor to provide the best redundancy available (see Redundancy with Cisco TelePresence Conductor, page 11-34). Alternate redundancy is also possible by using overlapping search rules. The search rule targeting the first choice should have a high priority, while rules targeting backup multipoint resources or secondary targets should be assigned a lower priority, thereby providing backup resources when the primary resource is unavailable. For further information about search rules in Cisco VCS, see the chapter on Dial Plan, page 14-1. Redundancy with Cisco TelePresence Conductor The Cisco TelePresence Conductor has the ability to be resilient in several ways: - Within the pool configuration - With the service preference - With clustering of Conductors - At the integration points with call control devices The TelePresence Conductor has the ability to manage conferencing resources such as the TelePresence Server and TelePresence MCUs. Within its configuration it has the ability to group those resources into pools. These pools of conferencing resources contain similar types of devices: TelePresence MCUs must be in a pool with other TelePresence MCUs only, and TelePresence Servers must be in a pool with other TelePresence Servers. In addition, it is best practice to try to differentiate the MCUs by HD or SD to allow for more granularity of the video services. This granularity will allow the administrative staff to assign endpoints such as the Cisco Unified IP Phone 9971 and the Cisco TelePresence System EX20 to the SD resources while making the HD resources available for the high definition endpoints such as the Cisco TelePresence System MX, EX, and C Series devices. In addition, all Cisco TelePresence System (CTS) and TX Series endpoints can be directed by the Conductor to use the TelePresence Server, which supports ActivePresence and TIP, to maintain the immersive experience for all participants. The ability to group conferencing resources by pools enables the Conductor to add redundancy at the pool level. Pool-level redundancy is achieved by having more than one device of a given type in the pool. The Conductor chooses between the multiple devices in a round-robin fashion by evaluating the number of conference ports being used at the time of conference setup. The conferencing device using the least number of ports will be chosen. In addition, the Conductor has the ability to create an ordered list of pools, which is called a service preference. It is similar to a route list or media resource group list in Unified CM. At this level of configuration, the Conductor can use primary and secondary pools to create a redundant model of conferencing resources. For example, if the service preference has a list of MCU pools in this order: Pool 1 for the US and Pool 2 for EMEA (see Figure 11-14), then the Conductor will use all the resources in the US pool of devices first and, if needed, it can make a cascaded link between the MCU in Pool 1 and the MCU in Pool 2. The Conductor does this automatically as a part of its intelligent conferencing selection process. The TelePresence Conductor can also be configured to use multiple Conductors for redundancy at the system level. This is achieved by clustering together multiple Conductors. A maximum of three TelePresence Conductors can be used in a clustered design. Cisco recommends at least two Conductors in all designs to ensure high availability of all the conferencing resources. Clustering Conductors requires a low-latency connection with less than 30 ms round trip between the Conductor nodes. During the clustering process, the Conductors perform a database synchronization of all table entries, such as aliases, templates, service preferences, pools, and present state table of the conference resource ports. The initial clustering process has to have a primary Conductor that is used as the initial database for the cluster. Once the initial process is done, any Conductor in the cluster can update the database that is synchronized across all the Conductor nodes. For more details on clustering, refer to the Cisco TelePresence Conductor deployment guides available at The Conductor can integrate with the Video Communications Server (VCS) and Unified CM in either a standalone or clustered scenario. In a clustered scenario this integration is different for the two call control devices, and a single Conductor or clustered Conductor cannot integrate into both call control devices at the same time. Cisco recommends setting up a SIP trunk between VCS and Unified CM, with the Conductor or Conductor cluster integrated with Unified CM as shown in Figure 11-15. When VCS is the primary call control integration point for the Conductor cluster, redundancy is achieved by adding the individual IP addresses of each Conductor cluster node, or the fully qualified domain name (FQDN) of each Conductor cluster node, or the FQDN of the Conductor cluster with round-robin DNS. These settings are configured under the policy services page of the VCS. For more details on clustering, refer to the Cisco TelePresence Conductor deployment guides available at When Unified CM is the primary call control integration point for the Conductor cluster, redundancy is achieved by having multiple connections to Unified CM for the instant and permanent conference calls. When the Conductor is clustered in this design, it requires unique virtual IP addresses that are the termination points for the Unified CM conference bridge and SIP trunk. Because the virtual IP addresses are unique on each Conductor cluster node, this information cannot be replicated in the database synchronization process and needs to be configured by the administrator. Once this configuration is complete, Cisco recommends using different Conductor cluster nodes for the primary, secondary, or tertiary links to Unified CM. For example, as illustrated in Figure 11-16, a Unified CM should be configured to use the virtual IP address of Conductor_1’s instant conference configuration as the primary connection, and the secondary connection is set to the virtual IP address of the instant conference configuration on Conductor_2. For the permanent calls, the destination address of the primary SIP trunk should be Conductor_2’s virtual IP address for the permanent conference configuration, and the secondary connection is set to the virtual IP address of the permanent conference configuration on Conductor_1. Note Additional redundancy can be achieved within Unified CM for instant and permanent conference calls. For more information, refer to the sections on Media Resource Groups and Lists, page 11-32, and Route List and Route Groups, page 11-33. Capacity Planning for Cisco Rich Media Conferencing Capacity planning is critical for successful rich media conferencing deployments. Given the many features and functions provided by Cisco Rich Media Conferencing services as well as the many different types of media resources used as part of the architecture, it important to size the rich media conferencing infrastructure and its individual components to ensure they meet the capacity needs of a particular deployment. This section provides information and best practices for sizing the media resources used in the Cisco Rich Media Conferencing architecture. Sizing the Conferencing Resources There are several factors involved in determining the types and number of conferences that a conference bridge can support. These sizing factors are different for different models of conference bridges. MCUs can also make available more ports when using standard definition (SD) mode as compared to the high definition (HD) mode, while voice conference bridges use less DSP processing when low-complexity codecs are used. Calculating the size of conference resources depends on the following factors: - The type of codec and resolution for the video conference - The total number of ports that the MCU can support, or the number of DSPs the conference bridge can support - The number of ports that the MCU can dedicate to each protocol - Whether cascading conferences are needed between MCUs For specific information about the number of ports or DSPs (in the case of voice conference bridges) supported, refer to the product documentation for your conference bridge hardware, available on http://www.cisco.com. Due to the almost infinite number of possible variations, it is not feasible to provide capacity numbers within this document for every scenario. Many Cisco Rich Media Conferencing deployments may use a mixture of SIP or SCCP instant conferences, H.323 and SIP reservationless conferences, and H.323 and SIP scheduled conferences. The conferencing resources must be sized to accommodate all of those types of conferences at the correct speeds and video layouts. Needless to say, this can become quite complex to determine, so Cisco has developed calculator tools to assist in sizing the conferencing resources. For sizing PVDM hardware, use the DSP Calculator available at http://www.cisco.com/web/applicat/dsprecal/dsp_calc.html Note Consult with your Cisco sales representative for assistance on sizing the conferencing resources for your particular environment. Resource Allocation and Allocation Logic A critical part of the Cisco Rich Media Conferencing design is to allocate the correct resources in the right place. However, to do this you first need to understand how the allocation logic works to allocate the right amount of resources in the corresponding location. Resource allocation also works differently in different call control applications. The following information applies to conferences that are initiated or processed by endpoints controlled by Cisco Unified CM: - If an instant conference that does not use the MultiSite or built-in bridge functionality is initiated by an endpoint registered to Unified CM, the resource is allocated based on the media resource group and list assigned to the conference initiator. All other endpoints in the conference just join their streams to the resource selected by the conference initiator. (See Figure 11-17.) - If a MeetMe video or audio conference is initiated by an endpoint registered to Unified CM, the resource is allocated based on the media resource group and list assigned to the conference initiator. All other endpoints in the conference just join their streams to the resource selected by the conference initiator. (See Figure 11-17.) If a permanent video conference is created, the conference call (all participants’ individual calls) will be processed based on the dial plan applicable to the call (permanent alias or number dialed) and off-loaded to the applicable trunk multipoint device. If a scheduled conference is create, the conference call (all participants’ individual calls) will be processed based on the dial plan applicable to the call and off-loaded to the applicable trunk multipoint device. The resource allocation logic for scheduled conferencing lies in the scheduling platform resource selection algorithm. In Figure 11-17, assume that the conference was initiated by endpoint A, which has its local resource as the first option in the media resource group list. Note how, for this particular conferencing example, the usage of the local resource is bandwidth intensive because there are more remote users than local participated in the conference, thus causing the remote users’ streams to traverse the WAN. The following information applies to conferences that are initiated or processed by endpoints controlled by Cisco VCS: - If an instant Multiway™ conference is created, the resource is selected based on the applicable selected search rule (the MCU automatically creates the conference once it detects the unknown conference number). All other participants’ media streams are joined to the resource selected by the conference initiator. - If a permanent or scheduled conference is created, the call is processed based on the applicable search rules. - The resource allocation logic for scheduled conferencing lies in the scheduling platform resource selection algorithm. For further information about the processing of media resources groups and lists, refer to the section on Media Resource Groups and Lists, page 11-32, and the chapter on Media Resources, page 7-1. Scalability Cisco recommends following the guidelines in this section to scale the design of your Cisco Rich Media Conferencing deployment. **Media Resource Groups and Lists** Make use of media resource groups and lists whenever possible to achieve the desired scalability for instant and MeetMe conferences in a Cisco Unified CM deployment. For example, see Figure 11-18, where two of MCUs are used to double the instant video conferencing capacity of Device Pool 2 by adding the two containing media resource groups into the media resource group list used by the pool. For more information on media resource groups and lists, see the chapter on Media Resources, page 7-1. **Figure 11-18 Example of Media Resource Groups and Lists** ![Diagram showing media resource groups and lists](image-url) Scaling Video Conferencing with TelePresence Conductor Make use of Cisco TelePresence Conductor to scale video conferencing services. TelePresence Conductor offers orchestration for multiple resources so that they can be allocated as needed, and it can span conferences through more than one multipoint resource when its capacity is exceeded. Figure 11-19 depicts an example of how a single Conductor server can improve the scalability of a deployment for instant video conferencing. In this example the resource allocation starts when the user (1) initiates a conference on Cisco Unified CM. This in turn sends the request (2) to the Conductor (3). The Conductor determines which is the most available resource to be utilized and creates the conference in the MCU (4). It then replies to Unified CM with the conference details (5), and Unified CM starts the conference signaling negotiations with the MCU (6). The media (RTP) flows point-to-point (directly) between the endpoint(s) and the MCU. TelePresence Conductor pools the resources, thus making all those collective resource available to Unified CM as if they were a single resource. Figure 11-19 Example of Cisco TelePresence Conductor Allocating Conference Resources For further information about Cisco TelePresence Conductor, see the section on Redundancy with Cisco TelePresence Conductor, page 11-34. The information and logic documented in that section also apply to increasing the scalability in a deployment. Clustering and Cascading Make use of clustering and/or cascading if your multipoint device supports it. (For the definition and functionality of cascading, see the section on Cascading, page 11-45.) Clustering multipoint blades in a Cisco TelePresence MSE 8000 series chassis has resource implications because it can triple or quadruple the amount of bandwidth that is required for that chassis. On the other hand, although cascading can be used to increase conference capacity while maintaining a distributed multipoint deployment, note that cascading can create an inconsistent meeting experience. Cascading is better automated by Cisco TelePresence Conductor. Table 11-7 summarizes information about which multipoint devices are capable clustering or cascading. Table 11-7: Multipoint Device Support for Clustering and Cascading <table> <thead> <tr> <th>Device</th> <th>Clustering</th> <th>Cascading</th> </tr> </thead> <tbody> <tr> <td>Cisco TelePresence Server</td> <td>Yes</td> <td>No</td> </tr> <tr> <td>Cisco MCU</td> <td>Yes²</td> <td>Yes</td> </tr> </tbody> </table> 1. Requires Cisco TelePresence Server MSE 8710, MCU 5300 Series, or MCU MSE 8510 blades in an MSE 8000 Series chassis. 2. The MCU 5300 can be configured for clustering when configured in a stack. Design Considerations for Cisco Rich Media Conferencing This section provides general guidance and recommendations for Cisco Rich Media Conferencing design. Cisco Rich Media Conferencing Deployment Models This section provides general information about the various Cisco Rich Media Conferencing deployment models. It also examines where and when each Cisco Rich Media Conferencing deployment model is most effective and best used. Cisco Hosted Solutions Cisco Collaboration Meeting Rooms (CMR) Cloud is a Cisco Rich Media Conferencing deployment model delivered through the cloud. Cisco CMR Cloud is a video collaboration service. It couples WebEx Personal Rooms and the cloud-based WebEx Video Bridge into one, always-available meeting experience. CMR Cloud is accessible from any standards-based video device. It provides simple, highly secure collaboration from the scalable Cisco WebEx Cloud. The cloud service is designed to help users make connections across their business community. All the call control and multipoint units reside in the cloud. For a conference to occur, the stream of every single participant’s endpoint must traverse the Internet; therefore, sizing of the correct Internet links is crucial for an optimal experience. Cisco CMR Cloud is geared to mid-size deployments. For more information about Cisco CMR Cloud, refer to the documentation available at Multiple Sites with Centralized Resources Centralized designs are recommended for voice and video deployments with few collaboration endpoints, and for larger deployments that extend over a limited geographical area. For centralized deployments, Cisco recommends locating the multipoint device at a regional or headquarters campus site with the necessary WAN bandwidth available to each of the remote sites, as well as the necessary LAN bandwidth within the campus. In addition, the multipoint device should be centrally located, based on the geographical location of the endpoints, to prevent unnecessary latency caused by back-hauling calls to a site at the far edge of the network, although this might not be entirely possible due to the existing network layout. Figure 11-20 depicts an example deployment of centralized resources with video endpoints located in Dallas, London, and San Jose. In this example the New York location was chosen as the geographically central location for the multipoint device, thus providing the least latency to the video users. Figure 11-20 Multiple Sites with Centralized Resources Multiple Sites with Distributed Resources Cisco recommends a distributed configuration for large voice and video deployments spread across separate geographical regions. As the collaboration network grows, it is very advantageous to distribute multipoint devices to minimize latency and save bandwidth across expensive WAN links. The Cisco TelePresence Server and MCU appliances (Cisco TelePresence Server 7010 and Cisco TelePresence MCU 4200, 4500, and 5300 Series) are suited for organizations moving from a centralized to a distributed deployment. As the collaboration network usage grows further, these deployments can evolve their standalone multipoint devices to chassis-based blades (Cisco TelePresence Server MSE 8710 and Cisco TelePresence MCU MSE 8420 and MSE 8510) for increased scale and redundancy. Figure 11-21 shows a distributed deployment with a multipoint device in New York providing multipoint services for North America, and a multipoint device in Paris providing multipoint services for Europe. Design Recommendations This section provides general recommendations for Cisco Rich Media Conferencing deployments. Latency For an optimal and natural experience regardless of deployment model, multipoint devices should be located at sites with one-way network latency of less than 150 ms between the multipoint device and any endpoints, provisioned with adequate port capacity and provided with ample bandwidth for the number of provisioned conferencing ports. Bandwidth requirements vary depending on the required maximum call rate of endpoints and the number of endpoints connecting to the multipoint device. Provision based on the maximum bandwidth that a particular endpoint requires for the desired call rate and resolution. For details, refer to the specific endpoints’ data sheets available on http://www.cisco.com. Cascading Cascading refers to the ability to bridge together conferences on two multipoint devices as one conference. This increases the maximum number of endpoints supported in a conference and can reduce bandwidth across links, depending on how the multipoint devices are deployed. Note that cascading conferences can create an inconsistent user experience, especially when features such as continuous presence are used by the endpoints. This is due to the remote conference appearing as just another endpoint on the local conference. When making use of cascading for a large briefing conference type, it is a best practice to have all slave MCUs set to full-screen voice switched, and the master MCU set to the desired Continuous Presence layout. All the main speakers should be located in the master MCU so that they can be provided with the best experience. MTP Used with a Conference Bridge Media termination points (MTPs) are used in a conference call when one or more participant devices in the conference use RFC 2833 signaling format. When the conference feature is invoked, Unified CM allocates MTP resources for every conference participant device in the call that supports only RFC 2833. This is regardless of the DTMF capabilities of the conference bridge used. Video Transcoding and Video Switching It is important to understand that video conference bridges accomplish their conferencing functionality by doing media transcoding or media switching. This transcoding or switching is perceived by the video conferencing users as the mixing of the media streams. Organizations looking to deploy a multipoint conferencing solution must understand the differences between transcoding and switching architectures because both architectures provide advantages that should be considered (see Table 11-8): - Transcoding involves specialized video hardware, allowing the incoming video to be decoded and then re-encoded before being sent on. - Switching does not require specialized video hardware but uses software instead. The incoming video and audio streams are copied and redirected to the correct endpoints. <table> <thead> <tr> <th>Method</th> <th>Advantages</th> <th>Disadvantages</th> </tr> </thead> <tbody> <tr> <td>Transcoding</td> <td>• ActivePresence (a special layout optimized for immersive experiences)</td> <td>• Latency is introduced due to decoding and re-encoding</td> </tr> <tr> <td></td> <td>• Ability for endpoints to connect at different bandwidth speeds and resolutions</td> <td>• Higher cost per port</td> </tr> <tr> <td></td> <td>• Endpoints can customize layouts</td> <td>• Harder to scale</td> </tr> <tr> <td></td> <td>• Ability to upscale low resolution video</td> <td></td> </tr> <tr> <td>Switching</td> <td>• Latency is extremely low (less than 10 ms)</td> <td>• Limited to basic full-screen video switching (No ActivePresence; only one site is visible on each screen)</td> </tr> <tr> <td></td> <td>• Lower cost per port</td> <td>• All endpoints must support and agree on a single resolution and frame rate</td> </tr> <tr> <td></td> <td>• Typically higher port capacity</td> <td>• Currently restricted to TIP endpoints</td> </tr> </tbody> </table> Table 11-8 Transcoding and Switching Advantages and Disadvantages
INTERACTIONAL FUNCTIONS OF ŞEY IN TURKISH: EVIDENCE FROM SPOKEN TURKISH CORPUS Türkçede şey’in Etkileşim İşlevleri: Sözlü Türkçe Derlemi’nden Bulgular Yasemin Erdoğan Karabük University 1 This article is an extended version of the paper presented at the 16th International Conference on Turkish Linguistics in Ankara. September 18-20, 2012. 2 yaseminerdogan@karabuk.edu.tr, erdogan.yasemin@metu.edu.tr Abstract: This corpus-based study investigates the interactional functions of Turkish discourse particle şey. The data was obtained from the demo version of the Spoken Turkish Corpus (STC). The study presents that şey is one of the most frequent discourse particles used in Turkish and has multiple interactional functions in conversations. In this regard, the main functions of şey in Turkish in natural conversations are self-repair, introducing / initiating a new topic, holding the floor and signaling a topic shift. In addition to its conversational turn organization functions, şey also functions as a face saving device in spoken language. Supporting the findings of the previous research on the discourse particle, the study further emphasizes that şey has a crucial role in natural conversations to smooth the interaction, organizing topic shifts and enabling cohesion. Key words: şey, Discourse Particle, Interactional Functions, Spoken Turkish Corpus 1. INTRODUCTION In everyday conversations of English and Turkish, there are a number of lexical items which are mostly used unconsciously yet frequently uttered by the speakers to smooth the interaction and enable cohesion in a conversation. These types of lexical items are called discourse particles or discourse markers (Schiffrin, 1987). With the growing number of research studies conducted on spoken interaction, discourse particles have gained a particular importance in the analysis of everyday conversations. They have a significant role in conversations since they fulfill a number of interactional functions. Before mentioning the functions of discourse particles in everyday speech, it is useful to define and describe the main characteristics of discourse particles. As Yılmaz (1994) suggests, discourse particles are “accepted to be devices that help individuals in conversation to achieve coherence.” They are also identified as lexical items which do not belong to any single grammatical category (Schiffrin, 1987), which may have flexible positions (initial, middle, final positions) in the sentence and which do not correspond to any specific meaning as a word (Yılmaz, 2004). The lexical items such as *well, I mean, you know, oh* in English and *yani, iştir, şey* in Turkish are examples of discourse particles or discourse markers in English. Generally, discourse particles do not affect the syntax of utterances or do not have a meaning as a lexical item on their own. Therefore, it can be inferred that their pragmatic functions make them significant rather than their syntactic or semantic functions (Yılmaz, 2004). Discourse particles have a crucial role in conversations in terms of their interactional functions. Although the speakers are not aware of this, they frequently use the various discourse particles in their speech. Discourse particles in everyday conversations enable the speaker to transfer messages in a clearer manner, interact smoothly, organize the order of the turns and turn-takings, direct the topics/messages in the conversation, and manage a coherent ongoing conversation. As Schiffrin emphasizes (1987), discourse particles help speakers locate themselves and their utterances in the ongoing construction of discourse. For this reason, those “small” items, as McCarthy (2003) names them, have “big” and significant impact on the direction, content and organization of a conversation. Erman (2001) names discourse particles as *pragmatic markers* and identifies pragmatic markers as ‘devices of monitoring discourse and conversation’ and ‘functional in the sense that they contribute nothing to the propositional content of the utterance in question, but occur outside the syntactic structure (cited in Oktar & Cem-Değer, 2004). --- 3 The terms ‘discourse marker’ and ‘discourse particle’ are used interchangeably in this study. In the light of the brief information presented above, this study aims to explore the interactional functions of the discourse particle şey in Turkish language in everyday spoken conversations. The idea of analyzing the functions of şey emerged from the observations that şey as a discourse particle in Turkish has a very frequent usage in the conversations with multiple forms and positions. The following section covers a brief overview of the research on discourse particles and on şey in particular. Section 3 presents the procedure of the corpus-based research and the occurrences of şey in Spoken Turkish Corpus Demo Version (hereafter STC DEMO) (Ruhi et al., 2010). In Section 4, the interactional functions of şey as a discourse particle in conversations are presented and supported with examples extracted from STC DEMO. 2. THEORETICAL BACKGROUND OF RESEARCH ON DISCOURSE PARTICLES 2.1. PREVIOUS STUDIES ON DISCOURSE PARTICLES Although the analysis of everyday natural conversations have been ignored for a long period of time, the study of lexical items and their functions have obtained a remarkable attention in the last few decades (Adolphs, 2006). Today, empirical studies with spoken data are commonly carried out in the field of pragmatics. With the growing attention on spoken conversation, it has been noticed that discourse particles, which always occur in everyday speech, have an important place in the organization and cohesion of conversations. The studies on discourse particles have gained a particular attention since then and the functions of discourse particles have started to be investigated in general or with specific emphasis on one or a number of particles. In Yılmaz’s terms, while “some of these studies deal with a whole range of discourse markers, the others concentrate on individual ones; also they are treated within larger discourse analytical frameworks” (1994). 2.2. REVIEW OF RESEARCH ON DISCOURSE PARTICLE ŞEY Before sharing the findings of the analysis on the discourse particle şey, it is useful to review the previous studies carried out on spoken discourse in Turkish language. Spoken discourse has become an area which has been investigated by Turkish linguists in the last two decades. There are a few research studies conducted on everyday conversations, discourse particles and the functions of some discourse markers/particles in Turkish. One of the most comprehensive and elaborate research on discourse markers has been done by Özbek (1995). In her study, Özbek compared a number of discourse markers including well and şey in English and in Turkish. She investigated the similarities and differences between the markers in different languages to find out whether the functions of discourse markers are universal or not. Her study is significant since it has revealed that the discourse markers, as she calls them, are one of the language universals and have similarities in their interactional functions. In another study, she investigated the functions of yani, işte and şey as Turkish discourse markers and emphasized that it is possible to use with suffixes and as a free standing marker in various grammatical positions. Similarly, Yılmaz (1994) carried out a research on the functions of discourse particles focusing on well and şey, which constitutes the core investigation topic in this case as well. Yılmaz investigated the similarities and differences between the usage and functions on two discourse particles mentioned above. Following his study in 1994, Yılmaz (2004) did another research in which he analyzed the three most common discourse particles in Turkish; işte, yani and şey. This study is worthy for its in-depth analyses on those three discourse particles. He concluded that the three particles have multiple functions and şey ‘marks the speaker’s temporary mental effort of extracting the linguistic information from the memory’ as well as ‘it displays caution and discretion and marks politeness when assessing/asserting something about the self or the other’ (Yılmaz, 2004). In addition to the studies of Özbek (1998) and Yılmaz (2004) on discourse markers yani, işte, şey in Turkish, there are other significant studies on several discourse particles in conversations. The functions of yani have been investigated by Ilgin and Büyükkantarçioğlu (1994). It is revealed in their study that yani embodies different interactional functions depending on the specific context it is used in and users’ intentions. All of these studies constitute significant cornerstones leading the investigations of spoken Turkish language. Similarly, Ruhi (2009) analyzed the functions of yani and concluded that ‘parenthetical yani serves to constrain the metarepresentation of referents and contributes to the derivation of implied meaning at the intentional level of the discourse, thereby often producing rhetorical, emotive effects.’ Oktar and Cem Değer’s (2004) study focused on the functions of iste as a pragmatic marker. They stated that iste is uttered in three domains: textual, social and metalinguistic domains and various functions are assigned to iste depending on the particular domain. The studies of Yılmaz (1994, 2004) and Özbek (1995,1998), which explore the interactional functions of şey, have consisted of spoken data recorded and transcribed by the researchers at times when electronic spoken corpora were not available for Turkish. The present research on şey is significant since the data has been retrieved from a corpus. The results may have significance in terms of controlling the consistency of functions of şey in previous research and comparing the findings of previous studies with the current corpus-based research. 3. şey IN SPOKEN TURKISH CORPUS 3.1. LEXICAL MEANING AND FORMS OF ŞEY IN CONVERSATIONS şey is one of the most frequently used discourse particles in Turkish language. According to the word definition given by The Turkish Language Association Dictionary (1998), the main meaning of the word şey is thing in English. Holding the meaning thing, şey can be combined with other words to constitute other nouns in Turkish such as; her şey: everything, hiçbir şey: nothing, herhangi bir şey: anything, bir şey: something. şey is generally used as a noun in the sentence while it carries the meaning of thing. Apart from its lexical meaning, şey is often used as a discourse particle to continue a conversation. Indeed, it is difficult to find a Turkish conversation without the discourse particle şey in everyday speech. şey embodies the basic characteristics and pragmatic functions of discourse particles. As explained with Schiffrin’s statements (1987), şey does not belong to any particular grammatical category, similar to the other discourse particles: (1) ((first name, male)) abiyle şey yapacaktım/ gönderecektim. (şey as a verb) ‘I would do şey/ with ((first name, male)) abi, send (it).’ (2) ne kadar basit şeyler bu istediklerin be oğlum! (şey as a noun) ‘Well son, how simple şeys you want!’ şey, as a discourse particle, can be placed in various positions in the sentence. It is found in initial, medial and final positions. There are two forms of şey in Turkish conversations; single standing şey and suffixed şey. At this point, it is useful to note that a suffixed discourse particle is unique to Turkish, compared to English. The reason for adding suffixes to a discourse particle, şey in our case is based on the structure of the language and the functions it fulfills. Since Turkish is an agglutinative language, sometimes şey may have nominal and verbal inflection suffixes in conversations. 3.2. şey IN STC In the study, a qualitative research design was employed to investigate the interactional functions of şey. Although the token number which will be stated below may seem insignificant for a quantitative corpus-based research, it is useful to remark once more that the main focus of this study is to analyze the pragmatic functions of şey in conversations so that a quantitative analysis is not the concern of the study. The data used in this study were retrieved from STC DEMO.\textsuperscript{4} STC DEMO is comprised of 23 different conversations in family/relative, service encounter and broadcast domains; 18357 tokens and 2.4 hours of spoken language audio recordings in Turkish, together with their written transcriptions. şey was searched in STC DEMO with EXAKT concordance tool in EXMARaLDA (Schmidt and Wörner, 2009). 301 tokens were extracted in the search. Nouns formed with şey (her şey, hiçbir şey, bir şey etc.), the number of which is 118, were excluded from the data used in the study because they did not fulfill any interactional function in conversations but embodied the lexical meaning of şey. Thus, the functions of 116 tokens were included and analyzed. The data retrieved from STC DEMO suggest that single standing şey with 116 tokens is the second most frequently used interactional marker after yani, the total token number of which is 188. However, with its suffixed and multi-word forms, şey outnumbers yani, which makes şey the most frequent interactional marker in STC DEMO, after non-lexical backchannels (e.g. hm, ha and hi-hi). Another noteworthy point to be mentioned is that both suffixed and single standing şey may be found in initial, middle and final positions in the sentences. The corpus data suggest that the most common place of şey in the sentence is the medial position while the least frequent place is the final position. Table 1. Classification of tokens of şey <table> <thead> <tr> <th>Types</th> <th>Token samples</th> <th>Examples</th> <th>No. of tokens</th> </tr> </thead> <tbody> <tr> <td>Single-Standing şey</td> <td>(I) Domain: conversation between family members</td> <td>BUR000030: ondan sonra şey, kısa isim istiyordum ben. 'Then, well, I actually wanted a short name.'</td> <td>116</td> </tr> </tbody> </table> \textsuperscript{4} The author has contributed recordings and transcriptions to STC. See Ruhi in this issue for details on the Spoken Turkish Corpus, its structure, content and its implementation with EXMARaLDA software suite to construct the corpus, transcribe, and analyze spoken language data. In this section, the pragmatic functions of şey as a discourse particle are presented under the categories of single standing şey, suffixed şey and şey in the domain of politeness with sample data extracted from STC DEMO. ### 4.1. INTERACTIONAL FUNCTIONS OF SINGLE-STANDING şey #### 4.1.1. SELF-REPAIRS One of the main functions of şey in a conversation is self-repair. In this type of use, şey is uttered as a corrector following the reperandum. In the first phase, the speaker produces a wrong utterance. Upon realization of the mistake, the speaker edits the error by linking the error and correct form of the lexical item with the use of şey. An example indicating the self-repair function of şey as a discourse particle has been presented below in a conversation between family members on the trees in their surroundings: ZEY000073: şeyi farkettik. Biz çok ayrı yaşamışız. Birbirimizin dilini bilmiyorumuz. ‘We noticed this. We lived apart for a long time. We don’t understand each other anymore.’ NEV000033: neyse bi malzeme mi bişey gelecekmiş. ‘Anyway, a material or something will appear.’ <table> <thead> <tr> <th>Suffixes</th> <th>şeyde, şeyden, şeydi, şeydir, şeye, şeyi, şeyim, şeyimiz, şeyin, şeyler, şeylerden, şeylere, şeyleri, şeylerin, şeyttirirdik</th> </tr> </thead> <tbody> <tr> <td>Nouns</td> <td>bişey, bişeye, bişeyi, bişeyim, bişeyle, bişeyler, bişeyse, bişeysi, hiçbişey, hiçbişeyi, hiçbişeyimi, her şey, bir şey, bi şey</td> </tr> </tbody> </table> (2) Domain: conversation between family members 4. ANALYSIS OF şey: ITS PRAGMATIC FUNCTIONS In this section, the pragmatic functions of şey as a discourse particle are presented under the categories of single standing şey, suffixed şey and şey in the domain of politeness with sample data extracted from STC DEMO. In this excerpt, CEV intended to say that the trees were cut. However, he produces the wrong word and utter ‘cars’ first instead of ‘trees’. When he notices that word was not the intended one, he interrupts his utterance and edits the error by using şey followed by the correctly uttered lexical item. In (4), a resident and her service provider in the apartment search the source of the noise occurring at noon, and SED declares that her house is empty at that specific time. In this conversation, şey fulfills a similar interactional function. Here, the speaker starts her sentence with the intention of forming a different word. Then, she notices that the word she just uttered is not correct. Following the reperandum, she produces the intended word which is ‘five’. Between the wrong utterance and alteration, the speaker uses şey to repair her mistake. In both of the examples analyzed above, the speakers stop immediately when they realized the error in their speech. They produce şey as a marker stating the repair of the error and utter the intended lexical item. As Yılmaz emphasizes (2004), şey both signals an ‘upcoming repair’ in the conversations and indicates that the speakers ‘monitor his/her speech production’ throughout the conversation. 4.1.2. INTRODUCING A TOPIC Another function of şey in naturally occurring spoken language is initiating a new topic or shifting the topic of the conversation. Mostly, the speakers in a conversation start a new topic by using the discourse particle şey at first and continue talking about the new topic. The conversation below is among two classmates discussing the arrangements for their vacation and constitutes an example for the function of şey as a topic initiator. (5) STC 117_090310_00019 BAD000036 ((0.1)) biz/bizim ((first name, female)) hoca haftaya yokmuş. • herkes eve gidecek. OZL000072 ((0.2)) ne güzel. OZG000035 ((0.9)) şey diyorum ((first name, female))! ((0.6)) biz ((0.4)) emm... ((0.2)) yani ikimiz ayarlarak gidelim BAD000036 ((0.1)) next week, we/our ((first name, female)) hoca is not here. • everyone will go home. OZL000072 ((0.2)) how nice. OZG000035 ((0.9)) I say şey ((first name, female))! ((0.6)) we ((0.4)) emm… I mean we may go together if we can arrange (for it). In this excerpt, BAD gives information about their professor’s absence at school to her friend, OZG. Then, OZG suggests to BAD that they go home together. Here, OZG starts a new conversation topic. While initiating this new topic to BAD, she starts her sentence with şey. It enables her to switch to the new topic in a soft manner. In excerpt (6), a conversation among family members between FAT, the aunt, and TUG, the niece of another family member is presented. FAT welcomes TUG and asks about what she has been doing. Following her answer, TUG changes the topic and starts a new one. By using şey at the beginning of her utterance, she gives new information about a person in the family to FAT. In this conversation, şey functions as a marker signaling the change of topic. One noteworthy observation is that while introducing or shifting the topic in a conversation, şey is mostly used at the initial position in the utterance. (6) STC 112_090217_00001 FAT000027 hoş geldin canım. iyiyiz. ((0.1)) sen ne yaptın? TUG000026 hoş bulduk. TUG000026 ((0.4)) ne yapayım ben de yaa! ((0.5)) şey ((first name)) sekizde çıkacaktı mış. FAT000027 welcome dear. we are fine. ((0.1)) how about you? TUG000026 thank you. TUG000026 ((0.4)) oh nothing special! ((0.5)) şey ((first name)) will be out of school at eight. 4.1.3. MARKING HESITATION, HOLDING THE FLOOR, PLANNING THE NEXT UTTERANCE One of the most significant functions of şey is its function of displaying hesitation. When the speaker is hesitant about his/her utterances, s/he uses şey to take the time until s/he is sure about her utterances. In this manner, s/he holds the floor. The reason why the three functions are combined under one heading is that the three functions establish the ground for each other. In other words, they are interrelated functions that are better handled together. Showing hesitation in the conversation allows the speaker to hold the floor. To hold the turn, the speaker needs to end the hesitancy, find the intended item or topic and plan for his/her next utterance. In excerpt (7), BUR explains her ideas on her daughter’s name to friends and family members. BUR inhales and uses a phrase including şey to hold her floor and plans her next utterance until she becomes sure about her next utterance. (7) STC 012_090128_00002 BUR000030 gerçekten son zaman ben de sıkılmaya başladım. (((0.2)) (inhales)) ardından şey... ((0.8)) kısa isim isterdüm ben. BUR000030 actually I was becoming bored. ((0.2)) (inhales)) then şey ... ((0.8)) I wanted a short name. In excerpts (8) and (9), şey has a similar function. In excerpt (8), CEV informs his wife on the new environment planning. In excerpt (9), BUR describes the content of the telephone and its card. Since the speakers are hesitant in the conversations, they appear to be searching for the appropriate lexical items to produce. In the meantime, they use şey to hold the floor and show that their turn is not over. At the same time, they plan their next utterances. şey acts as a device giving them time to organize their speech and keep their turns.\(^5\) (8) STC 072_090618_00005 CEV000041 o şeyin • yan tarafına/ ((0.1)) şu ee ormanın içine ve karşı tarafına da ((0.5)) kar ee emm s/ ş/ şey... ((0.3)) ne? ((inhales)) ((0.7)) kar yağDMA mAKINALARI KURULACAKMİŞ. CEV000041 near that şey / ((0.1)) / ee inside the forest and across ((0.5)) snow ee emm s/ ş/ şey ... ((0.3)) what? ((inhales)) ((0.7)) snow making machines will be set. (9) STC 012_090128_00002 BUR000030 şey ne diyecektim. _bak telefonda. _bak. ((0.3)) böyle kartında da var. BUR000030 şey, what was I going to say. _look, it is on the phone. _look. ((0.3)) It is also on its card. 4.2. şey WITH SUFFIXES As mentioned earlier, the discourse particle şey has suffixed forms in conversations. Similar to the single standing şey, suffixed şey can be placed at initial, medial and final positions in sentences as well. They also perform similar interactional functions in the conversations. The main difference between single standing şey and suffixed şey is that the latter takes the suffixes of gender, case, number, possession and aspect modal. There is one significant point to mention here and that is that şey is the only discourse particle that can have a suffixed form (Yılmaz, 1994). As has been mentioned earlier, unlike the other \(^5\) Although it is not observed regularly, şey follows and is followed by filled pauses and fillers such as ee, emm when it marks hesitation and signals for planning the next utterance in a number of conversations. particles such as *işte*, *yani*, *falan* etc., *şey* takes suffixes and can hold the place of the nouns, verbs and adjectives, depending on the suffixes that these take in the syntactic structure of the utterance. One important feature of suffixed *şey* is that it mostly replaces or substitutes a lexical item in the utterance due to hesitation and delay. When the speaker does not remember or find the correct lexical item, h/she simply replaces the missing word with suffixed *şey*. Depending on the suffixes of the lexical items that is ‘forgotten’, *şey* takes the suffixes of the substituted lexical item and belongs to the same grammatical category of the substituted lexical item. In some cases, the speaker remembers the intended word right after using *şey* and produces it. In other cases, however, the speaker does not produce the missing lexical item and only substitutes it with *şey*. As long as the message is conveyed between speakers, the lack of a substitution with a lexical item does not cause to a comprehension problem for the speakers. In excerpt (10), HAL helps her husband choose appropriate clothes. In excerpt (11) NEC talks about a movie he watched to his friends. Both excerpts display that suffixed *şey* replaces nouns and takes the suffixes belonging to those nouns. When the speakers remember the words, they immediately utter the intended word after suffixed *şey*. (10) STC 024_091113_00031 **HAL000098** (0.6) *o zaman siyah* (1.0) *emn giyeceksin* demektir. (0.5) *bence açık maviyle güzel olmaz.* • *bununla daha güzel olur.* (0.7) *bi üst üste koysana* (0.3) *şey/ ceketi.* (0.6) *pantalonun* (0.2) *yanına.* **HAL000098** (0.6) *then black* (1.0) *emm you are going to wear.* (0.5) *I think light blue does not fit.* • *it goes better with this one.* (0.7) *put* (0.3) *şey/ the jacket.* (0.6) *near* (0.2) *the trousers.* In contrast to the examples (10) and (11), excerpt (12) indicates a case where şey simply substitutes another word which is a noun, yet the intended lexical item after şey has not been uttered. It is probably because the interlocutor has already comprehended the word which is substituted by şey and the speaker does not need to correct the word in such a situation. As a final comment for single standing şey and suffixed şey, it can be inferred that both forms of şey have significant conversational functions enabling the speech to flow smoothly and conveying the messages in the conversations. 4.3. şey AS A MARKER OF POLITENESS Besides its conversational management functions, şey has a crucial role in politeness. As identified by Yılmaz (1994, 2004), şey may be used as a face mitigator in face-threatening situations (Brown & Levinson, 1987). In excerpt (13), OZG talks about the son of an acquaintance, who is not as tall as his peers. To express the fact that he is not tall, OZG prefers using şey instead of the adjective ‘short’. Her selection indicates that OZG wants to protect the face of the boy when she mentions a disadvantageous situation about him. Here, şey acts as a face mitigator for the speaker too since the speaker does not want to use a negative adjective about her acquaintance. She softens the negative meaning by using şey. In this way, she both saves the face of the boy and her own face since using negative words for the boy would damage her image among other people. (13)\(^{6}\) STC 117 090310_00019 \begin{verbatim} OZG000035 ha-ha’((laughs))’ BAD000036 ((01.)) kısa mı? OZG000035 ((0.3)) ha-ha’ e hafif böyle... OZG000035 ((1.0)) ((short laugh))’ he is of the same height as ((first name, male)). • my dear says • we are of the same height, how nice this is. and ((first name, male)) is a little ((0.3)) şey… IND000002 ((laughs))’ AYS000071 th ((0.3)) is he short? OZG000035 ha-ha’((laughs))’ BAD000036 ((01.)) is he short? OZG000035 ((0.3)) ha-ha’ a little… \end{verbatim} Similar to example (13), excerpt (14) is also an obvious example to the face saving function of şey. AYS talks about a teacher who is \(^{6}\) *tih*: utterance initializer; *ha-ha*: non-lexical backchannels and filled pauses are not translated in the excerpts. inexperienced in his field. Rather than using the adjective inexperienced, the speaker utters the word şey. As explicitly calling a teacher ‘inexperienced’ would be a threat to the face of the teacher, the speaker prefers to use a discourse particle, which softens the expression. At this point, şey acts as a mitigator against a face-threatening situation in the conversation. The speaker also saves his own face by avoiding uttering negative expressions for this teacher. Brown and Levinson put a particular focus on saving the faces of the hearer or the third person with the help of discourse markers (1987). However, excerpts (13) and (14) enable us to comprehend that şey allows the speakers to save their own faces as well as the other participants or third person. (14) STC 117_090310_00019 AYS000071 ee iki yıllık bir/ birisini de almışlar mesela. o da böyle şey/ hani çok ((0.7)) tecrübesi olan bi insan değil ama ((0.8)) almışlar. AYS000071 ee they also hired a person with two years of experience. and he is şey/ I mean ((0.7)) not very experienced but ((0.8)) they hired him anyway 5. CONCLUSION This study mainly discussed the functions of şey in spoken discourse. Upon the analysis of şey, it has become clear that it is one of the most common and frequently used discourse particles in spoken Turkish. It is used both as a single lexical item and with the addition of suffixes to the particle. It fulfills multiple conversational functions in spoken discourse. First, the single standing şey functions as a self-repair device. The speaker corrects the previously ‘mis-uttered’ items by using şey. Another function is initiating or switching to a new topic in the conversation. With the use of şey in especially the initial position in the utterance, the speaker can start or shift to another topic more smoothly. Speakers also use şey to hold their turn in the speech and to plan for their next utterance. As a hesitation marker, şey signals that the speaker needs time to produce the item and organize the speech. In addition to the functions of single standing şey, suffixed şey has an important place in naturally occurring conversations. It mainly enables smooth flow of speech by replacing and substituting the missing items in the conversation. In the cases of hesitation, forgetting or remembering the items later than expected, şey acts as a key item, providing the speaker with continuation in the speech while holding the floor at the same time. It is also worth noting that suffixed şey copies the morphological structure of the lexical item that it replaces or substitutes. The research supports the earlier studies (Yılmaz, 1994, 2004; Özbek, 1995, 1998) on şey as a discourse particle and contributes to the literature by putting particular emphasis on the interpersonal role of şey within the domain of politeness besides its conversational management functions. At the end of the research, it turned out that şey has a vital role in decreasing the face-threatening effect of the speech for both the speakers’ own face and for the others’ face. şey acts as a softener to save the faces of the participants and/or non-participants in conversations in Turkish. Şey is used as a marker of caution and discreetness in delicate topics of conversations. ACKNOWLEDGMENTS This study has been supported by TÜBİTAK 108K208 and METU, BAP-05-03-1011-001. I would like to express my sincere gratitude and appreciation to Professor Dr. Şükriye Ruhi for her valuable guidance and insight at each phase of this research. She introduced me to the field of pragmatics, provided me with the inspiration of studying spoken discourse, and broadened my scope with her enlightening courses. I also thank the two anonymous reviewers for constructive comments. REFERENCES Spoken Turkish Corpus http://stc.org.tr
Peering and Querying e-Catalog Communities Boualem Benatallah, Mohand-Said Hacid, Hye-Young Paik, Christophe Rey, Farouk Toumani To cite this version: Boualem Benatallah, Mohand-Said Hacid, Hye-Young Paik, Christophe Rey, Farouk Toumani. Peering and Querying e-Catalog Communities. 20th International Conference on Data Engineering, ICDE 2004, Apr 2004, Boston, United States. pp.846-846, 10.1109/ICDE.2004.1320076 . hal-01586012 HAL Id: hal-01586012 https://hal.archives-ouvertes.fr/hal-01586012 Submitted on 8 Mar 2019 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Peering and Querying e-Catalog Communities Boualem Benatallah\textsuperscript{1}, Mohand-Said Hacid\textsuperscript{2}, Hye-young Paik\textsuperscript{1} Christophe Rey\textsuperscript{3} and Farouk Toumani\textsuperscript{3} \textsuperscript{1} CSE, University of New South Wales, Australia, \{boualem,hpaik\}@cse.unsw.edu.au \textsuperscript{2} LIRIS, University Lyon I, France, mshacid@liris.univ-lyon1.fr \textsuperscript{3} LIMOS, ISIMA, University Blaise Pascal, France, \{rey,ftoumani\}@isima.fr UNSW-CSE-TR-0319 July 2003 Abstract An increasing number of organisations are jumping hastily onto the online retailing bandwagon and moving their operations to the Web. A huge quantity of e-catalogs (i.e., information and product portals) is now readily available. Unfortunately, given that e-catalogs are often autonomous and heterogeneous, effectively integrating and querying them is a delicate and time-consuming task. More importantly, the number of e-catalogs to be integrated and queried may be large and continuously changing. Consequently, conventional approaches where the development of an integrated e-catalog requires the understanding of each of the underlying catalog are inappropriate. Instead, a divide-and-conquer approach should be adopted, whereby e-catalogs providing similar customer needs are grouped together, and semantic peer relationships among these groups are defined to facilitate distributed, dynamic and scalable integration of e-catalogs. In this paper, we use the concept of e-catalog communities and peer relationships among them to facilitate the querying of a potentially large number of dynamic e-catalogs. E-catalog communities are essentially containers of related e-catalogs. We propose a flexible query matching algorithm that exploits both community descriptions and peer relationships to find e-catalogs that best match a user query. The user query is formulated using a description of a given community. 1 Introduction Nowadays, a large number of suppliers are offering access to their product or information portals (also called e-catalogs) via the Web. However, the technology to organise, search, integrate, and evolve these e-catalogs has not kept pace with the rapid growth of the available information. One of the key issues is how to efficiently integrate and query large, intricate, heterogeneous information sources such as e-catalogs. A popular approach for locating products within e-catalogs is the use of information retrieval based search tools (e.g., search engines) [8]. Though search engines are useful, they present some fundamental drawbacks such as limited search capabilities and lack of information-space organisation [14]. To address this issue, there has been a renewed interest in leveraging traditional data integration techniques because of support for semantically rich queries (e.g., data source structure aware queries) [8, 13]. Clearly, a brute force data integration approach, where the development of an integrated schema requires the understanding of both structure and semantics of all schemas of sources to be integrated, is hardly applicable because of the dynamic nature and size of the Web. Therefore, the effective sharing of a potentially large number of dynamic e-catalogs, requires more scalable and flexible data sharing and querying techniques. In this paper, we overview the design and implementation of WS-CatalogNet: a Web services based data sharing middleware infrastructure whose aims is to enhance the potential of e-catalogs by focusing on scalability and flexible aspects of their sharing and access. The salient features of WS-CatalogNet are: - **Ontological Organisation:** We use the concept of e-catalog community as a way of organising and integrating a potentially large number of dynamic e-catalogs [8]. An e-catalog community is a container of e-catalogs (i.e., e-catalogs offering products of a common domain such as Laptops or PCGames). It provides an ontological description of desired products (e.g., offered product categories, product attributes) without referring to any actual provider. Communities of e-catalogs are established through the sharing of high-level meta-information. Actual providers can register with any community of interest to offer the desired products. E-catalog providers can join or leave any community of interest at any time. Communities provide a way to meaningfully organise and divide the information space into groups of manageable spaces (e.g., putting similar products together). - **Decentralised Information Sharing:** Existing e-catalog organisation techniques usually use centralised categorisation and indexing schemes, whereas the participating e-catalogs are distributed and autonomous [15, 23]. A centralised categorisation and indexing model has several drawbacks including scalability, flexibility, and availability [12, 21, 18]. Given the highly dynamic and distributed nature of e-catalogs, we believe that novel techniques involving peer-to-peer centric categorisation and indexing schemes will become increasingly attractive. Our approach features the use of peer relationships among e-catalog communities to allow decentralised sharing of catalog information. Query routing between communities is based on such relationships (even with no or minimal knowledge of the schema about the other party). The objective is to achieve scalable information sharing and access through the incremental meta-data driven discovery and formation of inter-relationships between e-catalog communities. - **Flexible Selection of Relevant e-Catalogs:** Because of the variety of e-catalogs offering similar information and the large number of available e-catalogs, it is important to provide appropriate support to first select those e-catalogs that are relevant to a specific user query, before actually querying them. In addition, catalog selection techniques should support flexible matching since it is unrealistic to expect queries and catalog descriptions to exactly match. In our approach, a user query is expressed using descriptions from a community ontology. We formalise relevant e-catalog selection as a new instance of the query rewriting problem [13, 4], where a user query is reformulated in terms of: - local queries (i.e., the part of the user query that can be answered by some e-catalogs registered with the actual community), - outsourced queries (i.e., the part of the user query that can be forwarded to other communities based on specific peer relationships), and - remaining parts of the user query that cannot be answered by the actual community. We proposed a characterisation of several types of relevant query rewritings (e.g., rewritings that minimise the part of the query that can not be answered by the community). We provide a formalisation of query rewriting in the context of category hierarchy based ontologies and propose a hypergraph-based algorithm to effectively compute best rewritings of a given request. The paper is organised as follows. Section 2 discusses the design overview, where we introduce main concepts of our approach. In section 3, we present query rewriting mechanism for selecting relevant e-catalogs. Section 4 describes an algorithm for computing query rewritings. In section 5, the implementation and experiments are presented. Finally, section 6 discusses related work and conclusions. ## 2 Design Overview In this section, we introduce the concept of catalog communities [19] and peer relationships among them. 2.1 Catalog Communities A catalog community is a container of product catalogs of the same domain (e.g., community of Laptops). It provides a description of desired products without referring to actual product providers (e.g., www.laptopworld.com). A community maintains categories for the domain it represents. A category is described by a set of attributes. For example, the community Laptops may have a category Laptop, which is described by attributes such as Name, CPU, RAM, HDD, ThinkLight, Ultrabay, Weight and Price. For the catalog providers to be accessible through a community, they must register their catalogs with the community. When registering, the catalog provider supplies a capability description which specifies what kind of products are supported, in terms of the community categories. The registration process allows a product provider and a community to form, a MemberOf relationship (e.g., CompaqPC provider may be a member of DesktopPC community). More precisely, a community maintains two disjoint sets of categories; core categories and outsourced categories. Products that belong to the core categories are supported by the community’s own members. The outsourced categories are defined as a way of extending the range of products provided in the community. The outsourced categories offer, for example, products that are not included in the core categories, that can be alternative choices, or recommendations to the products in the core categories. These outsourced categories are supported by external data sources which are outside the community (e.g., members in other communities). We use the term community schema to denote the description of a community which is expressed in terms of categories and attributes. Figure 1 shows the community of Laptops which has core, outsourced categories and registered members. ![Diagram of Community of Laptop, its categories and members](image) Note that the distinction between core and outsourced categories is transparent to users. In fact, users will see them as one set of categories without being aware of the differences in the sources of the data. Synonym Index. The terms used in community schema are different from one community to another. To help solve any mismatch problem, we use synonym-based matching approach. A community description also contains a list of synonyms for each category and attribute name used in the community. For example, for the attribute CPU, synonyms are \{processor, chipset, chip\}. These synonyms are used to translate queries across communities. 2.2 Peering Catalog Communities Communities are related by PeerOf relationships. We consider two types of peer relationships: - **Similarity**: Community \(C_1\) is similar to \(C_2\), when \(C_1\) has categories that are considered analogous, or interchangeable to \(C_2\)’s core categories (e.g., CD-RW Drives in \(C_1\) and CD-RW/DVD in \(C_2\)). - **Companionship**: \(C_1\) is a companion of \(C_2\) when \(C_1\) has categories that can support outsourced categories in \(C_2\) (e.g., \(C_1\) has an outsourced category Blank CD Media and \(C_2\) has a category that contains such products). Defining peer relationships determines how communities interact with each other. Figure 2 shows communities and peer relationships among them. Communities ![Figure 2: Peering catalog communities](image) and peer relationships are used to divide a vast information space into meaningful, manageable spaces. Forming Relationships. As shown in the figure 2, the relationships are directed. Let us assume the following scenario. Community \(C_1\) wants to form a relationship with \(C_2\) (either in the context of similarity or companionship). Also, \(C_1\) wants to forward the query \(Q\) to \(C_2\) via the peer relationship. \(Q\) is composed as follows using attributes in \(C_1\): \[ \begin{align*} (Q) \\ \text{SELECT name, displaySize} \\ \text{FROM Category_DesktopReplacement} \\ \text{WHERE price < 3000} \end{align*} \] Since the terms used in descriptions are different in the two communities, \( C_1 \) needs to know how a query described in \( C_1 \)'s terms should be translated to \( C_2 \)'s terms (i.e., mapping description). We consider three possible ways of describing the mappings. - **Full Mapping:** \( C_1 \) provides explicit mapping description specifying how the categories in \( C_1 \) can be mapped to categories (respectively, the attributes) in \( C_2 \). This mapping description is stored in \( C_1 \). Therefore, the query expressed in \( C_1 \)'s terms (i.e., \( Q \)) can be translated into \( C_2 \)'s terms. - **Partial Mapping:** \( C_1 \) does not specify mapping description for the attributes associated, but provide what kind of categories are available in \( C_1 \). In this case, the mapping only describes which category in \( C_1 \) maps to which is category in \( C_2 \). When \( C_1 \) only has mappings for categories, \( C_1 \) translate \( Q \) so that the category name is understood by \( C_2 \) (see FROM clause in Q.1). Then, for each attribute in \( Q \), a list of synonyms is attached (as shown in Q.1). \( C_2 \) will use the synonyms to match the attributes. (Q.1) ```sql SELECT name (title, product), displaysize (display, viewable size) FROM Category_PowerLaptop WHERE price (retail price, listed price) < 3000 ``` - **No Mapping:** \( C_1 \) does not specify any explicit mapping description with \( C_2 \). In this case, it is left to \( C_2 \) to figure out how to answer \( C_1 \)'s queries. When there is no mapping available, synonyms for attributes (respectively for categories) are identified and attached to \( Q \) before forwarding (as shown in Q.2). (Q.2) ```sql SELECT name (title, product), displaysize (display, viewable size) FROM Category_DesktopReplacement (PowerLaptop) WHERE price (retail price, listed price) < 3000 ``` \( C_2 \) refers to the synonyms to find alternative attribute/category names to match the terms in the query with \( C_2 \)'s own terms. ### 2.3 Basic Definitions This section introduces a (concept) class description language that belongs to the family of description logics [3]. We use this language to describe catalog communities and peer relationships between them. The proposed language is in fact a simple description logic that is designed to represent the domain of interest in terms of classes (unary predicates) and attributes (binary predicates). The classes and attributes characterise subsets of the objects (individuals) in the domain. This language will be used as a basis for formalising query reformulation across e-catalogs and communities. Class descriptions are denoted by expressions formed by means of the following constructors: - class conjunction ($\land$), e.g., the class description $\text{Peripherals} \land \text{SCSI}$ denotes the class of individual instances of the class $\text{Peripherals}$ and $\text{SCSI}$ (e.g., a $\text{HardDrives}$), - the universal attribute quantification ($\forall R.C$), e.g., the description $\forall \text{releaseDate}$. $\text{Date}$ specifies that the data type of the role $\text{releaseDate}$ is $\text{Date}$, - the existential attribute quantification ($\exists R$), e.g., the description $\exists \text{Ultrabay}$ denotes the class of individuals having at least one value for the attribute $\text{Ultrabay}$. Syntax and semantics of class descriptions are defined below. **Definition 1 (syntax and semantics)** Let $\mathcal{CN}$ be a set of class names and $\mathcal{A}$ be a set of attribute names. Class descriptions are inductively defined as follows: - $C$ is a class description for each class name $C \in \mathcal{CN}$. - Let $C, D$ be class descriptions and $R \in \mathcal{A}$ an attribute name. Then $C \land D$, $\forall R.C$ and $(\exists R)$ are class descriptions as well. A model-theoretic semantics for this language is given by an interpretation $\mathcal{I} = (\Delta^\mathcal{I}, \mathcal{I})$. It consists of a nonempty set $\Delta^\mathcal{I}$ the domain of the interpretation, and an interpretation function $\mathcal{I}$. The interpretation function associates with each class name $C \in \mathcal{CN}$ a subset $C^\mathcal{I}$ of $\Delta^\mathcal{I}$, and with each attribute name $R \in \mathcal{R}$ a binary relation $R^\mathcal{I} \subseteq \Delta^\mathcal{I} \times \Delta^\mathcal{I}$. Additionally, the extension of $\mathcal{I}$ to arbitrary class descriptions has to satisfy the following equations: - $(C \land D)^\mathcal{I} = C^\mathcal{I} \cap D^\mathcal{I}$, and - $(\forall R.C)^\mathcal{I} = \{ x \in \Delta^\mathcal{I} | \forall y : (x, y) \in R^\mathcal{I} \Rightarrow y \in C^\mathcal{I} \}$. - $(\exists R)^\mathcal{I} = \{ x \in \Delta^\mathcal{I} | \exists y : (x, y) \in R^\mathcal{I} \}.$ Based on this semantics, the notions of subsumption and equivalence between class descriptions are defined as follows. Let $C$ and $D$ be class descriptions: - $C$ is subsumed by $D$ (noted $C \sqsubseteq D$) if $C^\mathcal{I} \subseteq D^\mathcal{I}$ for all interpretation $\mathcal{I}$. - $C$ is equivalent to $D$ (noted $C \equiv D$) if $C^\mathcal{I} = D^\mathcal{I}$ for all interpretation $\mathcal{I}$. The basic concepts of the data model we use (e.g., category, community, member description, etc) are defined using a class description language. - A category represents a set of products that share common properties. A category definition is specified as follows: $\text{Cname} \equiv \text{CatDescr}$, where – Cname is the name of the category, – CatDescr is a class description that defines the category Cname. For example, the category Laptop may be described as follows: Laptop ≡ Computer \(\forall\) Name.String \(\exists\) Name \(\forall\) Weight.Number \(\forall\) OS.String... • A member definition specifies the capabilities of a given product provider as follows: \(\text{Mname}_\text{Dname} \equiv \text{MDescr} \) where \(\text{Mname}_\text{Dname}\) is a member definition name made of Mname, a member name (i.e., an unique identifier of a member), and Dname, the name of a description. MDescr is a class description that specifies which data is actually provided by this member. Each member can provide several definitions. For example, the IBM provider who offers a specific type of laptops (e.g., IBM laptops) can register to the catalog community with the following member definition: IBM_Laptop = Laptop \(\forall\) ThinkLight.String \(\forall\) Ultrabay.String... • A community has two types of peer relationships: companionship and similarity. – the companionship relationship is formalised as a set of outsourced categories, denoted by \(V\). – The similarity relationship is a set of community names \(C_i\) that has similarity type peer relationships with the community, and is denoted by \(S = \{C_i\}\). • A community schema consists of a tuple \(\text{CS} = (C, S, V)\), where \(C\) is a set of category definitions, \(S\) is a set of community names that are similar to the actual community, \(V \subseteq C\) is a set of outsourced categories definitions, • A catalog community consists of a tuple \(\text{CAT} = (\text{CS}, M)\), where \(\text{CAT}\) is the catalog name, \(\text{CS}\) is a community schema, and \(M\) is a set of member definitions. We assume that the set of class descriptions in a community catalog (i.e., core/outsourced category definitions and member definitions) is acyclic i.e., there does not exist cyclic dependencies between class definitions. Without loss of generality, we assume that the class names (respectively, the attribute names) that are used in the member definitions are disjoint from those used in the outsourced categories definitions. 3 Relevant e-Catalog Selection In our previous work [19, 8], we used browsing and keyword-based searching to locate communities of interests. In this paper, we focus on relevant e-catalogs selection. Once a community of interest is located, a query to select relevant e-catalogs can be expressed using the community schema. Since a community does not store product data locally, answering a user query requires locating e-catalogs that are most likely relevant to a user query. It is noted that a user query is expressed over the community schema. In the remainder, we refer to such query as a community query. These e-catalogs are selected from the community members and the members of communities that can be reached via peer relationships. We propose a selection mechanism that works as follows: given a community \( \text{CAT} = (CS, M) \) and a query \( Q \), expressed as a class description in terms of the schema of \( \text{CAT} \), our task is to identify: (a) a set of local member definitions that can answer all (or part of) the query \( Q \). For each selected member, we compute the part of the query to be sent to this member. (b) the part of the query that can be answered by companion communities. Again, for each selected companion community, we compute the precise part of the query to be forwarded to this community. (c) the part of the query that cannot be answered by the actual local members nor by the companion communities. This part of the query will be forwarded to other communities via similarity peer relationships, according to a forwarding policy. Detailed description of the forwarding policy will be given below. 3.1 Overview We propose a query answering approach that consists of the following elements. A Flexible Query Rewriting Algorithm. Existing query rewriting approaches are usually based on (containment) subsumption or equivalence between a given query and its rewritings [4, 13]. These approaches are not flexible enough to cater for the identification of the part of a query that cannot be answered by a given set of communities (see, requirement (c) mentioned above). We propose a novel query rewriting algorithm where the relationship between a query \( Q \) and its rewritings goes beyond simple subsumption or equivalence. It takes as input a community \( \text{CAT} = (CS, M) \) and a query \( Q \) over the schema of \( \text{CAT} \). It computes a set of rewritings \( R(Q) = \{r_i(Q)\} \). A rewriting \( r_i \) is a triplet \( r_i = (Q_{local}, Q_{outsourced}, Q_{rest}) \) where: - \( Q_{local} = \{(q_j, m_j)\} \) is a set of pairs \( (q_j, m_j) \) where \( q_j \) is the part of the query \( Q \) that can be answered by the member definition \( m_j \). \( Q_{\text{outsourced}} = \{(Q'_j, C_{oij})\} \) where \( Q'_j \) is the part of the query \( Q \) that can be answered by the outsourced category \( C_{oij} \). The expected results of this part of the query is a set of external members that are relevant to answering \( Q'_j \). \( Q_{\text{rest}} \) is the part of the query \( Q \) that cannot be answered by the members of the actual community nor by the members of its companion communities. This part of the query will be forwarded to the similar communities according to the community forwarding policy. Again, the expected results of the forwarding is a set of external members that are relevant to answering this part of the query. **Forwarding Policy.** A forwarding policy dictates whether and when the forwarding should be initiated, what should be forwarded and permitted hop count. It should be noted that this policy only concerns peer communities with similarity relationships. The basic structure of a forwarding policy is as follows: ``` forwarding policy: when empty | always | expand | busy what query | rest [-target community...] hop n ``` The policy requires three attributes to be specified: \textit{when}, \textit{what} and \textit{hop}. The attribute \textit{when} is used to decide when the forwarding should be initiated. If it is \textit{empty}, the query is forwarded when the result from local members is empty (i.e., no match), whereas \textit{always} implies that the query is always forwarded. \textit{expand} is used when the community wishes to expand the size of the result. \textit{busy} means that the query is forwarded when the community is busy (i.e., overloaded) with other requests. The attribute \textit{what} is used to decide which part of the query should be forwarded. That is, if it is set to \textit{query}, the original query \( Q \) is forwarded. If it set to \textit{rest}, the \( Q_{\text{rest}} \) part of \( Q \) is forwarded. When the \textit{-target} parameter is used, the query is forwarded only to the communities that appear in the \textit{community} clause. The default is to forward to all peers known via similarity peer relationships. 3.2 Query Rewriting In this section, we discuss our approach for community query reformulation. The reformulation translates a community query \( Q \), to queries that are expressed in terms of descriptions of community members and outsourced categories (i.e., a \( Q_{\text{local}} \) and a \( Q_{\text{outsourced}} \) parts of \( Q \)) and a \( Q_{\text{rest}} \) part of a query \( Q \). The rewriting problem can be stated as follows: Let \( C = \{c_i \equiv \text{description}_i, i \in [1, n]\} \) be a set of class definitions corresponding to member or outsourced category definitions, and let \( Q \) be a class definition that denotes a community query. Then, can \( Q \) be reformulated as a conjunction of class names \( E \equiv c_{i_1} \sqcap \ldots \sqcap c_{i_m} \), with \( 1 \leq m \leq n \) \(^1\) We use the terms user query and community query interchangeably. and $c_i \in C$ for $1 \leq j \leq m$, such that $E$ contains as much as possible of common information with $Q$? ($E$ is called a rewriting of $Q$ using $C$.) To formally define this kind of query rewriting, it is necessary to characterise the notion of “extra information”, i.e., the information contained in one class description and not contained in the other. For that, a difference or subtraction operation on class descriptions is required. To tackle this issue, we use known techniques in description logics [22] as described below. **Difference Operation on Class Descriptions.** An extension of description logics with a difference operation is studied in [22]. Roughly speaking, the difference of two descriptions $C$ and $D$, denoted as $C - D$, is defined as being a description that contains all information which is a part of the description $C$ but not part of the description $D$. This definition of difference operation requires that the second operand subsumes the first one. However, in case the operands $C$ and $D$ are incomparable w.r.t the subsumption relationship, then the difference $C - D$ can be computed by determining the least common subsumer of $C$ and $D$, that is, $C - D := C - lcs(C, D)$, where $lcs(C, D)$ denotes the least common subsumer of $C$ and $D$. In the sequel, for a sake of clarity we use $C - D$ to denote $C - lcs(C, D)$. Teege [22] provides sufficient conditions to characterise the logics where the difference operation is always semantically unique (i.e., the result of $C - D$ is unique modulo the equivalence of descriptions) and can be implemented in a simple syntactical way by constructing the set difference of sub-terms in a conjunction. From the results presented in [22], we can derive the following properties of our class description language: - Each class description $C$ can be expressed using a normal form, called Reduced Clause Form (RCF), as a conjunction of atomic clauses (e.g., $A_1 \land \ldots \land A_m$). In our language, a RCF of a class description $C$ is obtained by the following normalisation process: - unfolding $C$ (i.e., replacing each class name that appears in $C$ by its description until no more defined class names occur in $C$). - recursively rewriting each description $\forall R. (B \land D)$, where $B, D$ are class descriptions, that appear in the description $C$ into the equivalent description $\forall R. B \land \forall R. D$. As the set of class descriptions in a community is acyclic, the normalisation process is guaranteed to terminate. At the end of the normalisation process, each conjunct that appear in the normal form of the description $C$ constitutes an atomic clause of $C$. --- 2Informally, a least common subsumer of a set of (concept) class descriptions corresponds to the most specific description which subsumes all the given descriptions [3]. The difference between two class descriptions $C$ and $D$ can be computed using the simple set difference operation between the sets of atomic clauses of $C$ and $D$. Moreover, we define the size $|C|$ of a class description $C$ as being the number of clauses in its RCF. Note that, in the used language, a given class description has only one RCF. **Problem Statement.** Now let us introduce some basic definitions to formally define the query rewriting problem. Let $C = \{ c_i \equiv \text{description}_{\text{i}}, i \in [1, n] \}$ be a set of class definitions corresponding to member definitions or outsourced categories, and $E$ be a conjunction of some class names occurring in $C$. **Definition 2 (query rewriting)** A rewriting of $Q$ using $C$ is a conjunction $E$ of some class names $c_i$ from $C$ such that: $$Q - E \neq Q.$$ Hence, a rewriting of a query $Q$ using $C$ is defined as being a conjunction of class names occurring in $C$ that share some information with $Q$. We use the expression $\text{rest}_E(Q) = Q - E$, to denote the part of a query $Q$ that cannot be answered by the rewriting $E$ (i.e., the $Q_{\text{rest}}$ part of $Q$, if $E$ is selected as relevant to answering $Q$). In practical situations, however, we are not interested in all kinds of rewritings. Therefore, we define additional criteria to characterise the notion of relevant rewritings. For example, it is clearly not interesting to consider those rewritings that do not minimise the $Q_{\text{rest}}$ part of the query $Q$. That is, the part of $Q$ that cannot be answered by the local members nor by the companion communities. **Definition 3 (best cover rewriting)** A conjunction $E$ of some class names $c_i$ from $C$ is a best cover rewriting of $Q$ using $C$ iff: - $E$ is a rewriting of $Q$ using $C$. - there does not exist a rewriting $E'$ of $Q$ using $C$ such that: $|(\text{rest}_{E'}(Q))| < (|\text{rest}_E(Q))|$. Best cover rewritings correspond to those rewritings that minimise the size of $Q_{\text{rest}}$ part of a query $Q$. Hence, they are clearly relevant rewritings in practical situations (e.g., see [5]). However, usually it may not be interesting or efficient to compute all the possible best cover rewritings. The following two definitions characterise, among the best cover rewritings, those that are more relevant in practical situations. **Definition 4 (non redundant rewriting)** A conjunction $E = c_{i_1} \cap \ldots \cap c_{i_m}$, with $1 \leq m \leq n$ and $c_{i_j} \in C$ for $1 \leq j \leq m$ is a non redundant rewriting of $Q$ using $C$ iff: • \( E \) is a best cover rewriting of \( Q \) using \( \mathcal{C} \). \[ \forall j \in [1, m], E' = c_i \cap \ldots \cap c_{i-j-1} \cap c_{i+j+1} \cap \ldots \cap c_m \text{ is not a best cover rewriting of } Q \text{ using } \mathcal{C}. \] Definition 4 states that it is not possible to remove any class name from the description of a non redundant rewriting without modifying the \( Q_{\text{rest}} \) of the query \( Q \). In other words, the notion of non redundant rewriting characterises those rewritings that select only the local members (respectively, outsourced categories) that minimise the size of the \( Q_{\text{rest}} \) part of the query \( Q \). Such rewritings allows minimising the number of e-catalogs that will be selected for providing the answer to a given community query. This, for example, may be useful to minimise the communication cost. Finally, Definition 5 given below characterises the notion of best quality rewriting, i.e., a rewriting that maximise the user satisfaction with respect to a given set of Quality of Service (QoS) criteria. We assume that there is a scoring function, denoted \( \text{qual}(E) \), that returns a positive value which measures the quality of the rewriting \( E \) (i.e., the higher the value of \( \text{qual}(E) \), the higher the quality of \( E \)). This can be, for example, a multi-attribute utility that computes a quality score of an e-catalog based on pre-defined non-functional properties of the e-catalog (e.g., reliability, execution time) [25]. Further discussion about the used QoS model is outside the scope of this paper due to space reasons. **Definition 5 (best quality rewriting)** A conjunction \( E \) of some class names \( c_i \) from \( \mathcal{C} \) is a best quality rewriting of \( Q \) using \( \mathcal{C} \) iff: - \( E \) is a best cover rewriting of \( Q \) using \( \mathcal{C} \). - there doesn’t exist a rewriting \( E' \) of \( Q \) using \( \mathcal{C} \) such that \( \text{qual}(E) < \text{qual}(E') \). Best quality rewritings are defined as being the highest quality rewritings that minimise the size of \( Q_{\text{rest}} \) (as they are also best cover rewritings). ### 3.3 Mapping Rewritings to Hypergraph Transversals In this section, we investigate the computational problems associated to our proposed query rewritings (e.g., computing all the best quality rewritings of a query \( Q \)). To achieve this task, we provide a full characterisation of the proposed query rewritings in terms of hypergraph transversals. Our motivation is to reuse and adapt existing techniques in hypergraph theory to efficiently solve such computational issues. First, we look at the computation of each kind of rewriting (e.g., best quality rewritings) and determine the complexity for obtaining a solution for it. Then, in the next section, we propose a hypergraph-based algorithm for computing the best quality rewritings of a query \( Q \) using a set of class definitions \( \mathcal{C} \). Let us first recall some useful definitions regarding hypergraphs. For more details about hypergraphs theory, we refer the reader to [6, 10]. Definition 6 (hypergraph and transversals) [10] An hypergraph $\mathcal{H}$ is a pair $(\Sigma, \Gamma)$ of a finite set $\Sigma = \{V_1, \ldots, V_n\}$ and a set $\Gamma$ of subsets of $\Sigma$. The elements of $\Sigma$ are called vertices, and the elements of $\Gamma$ are called edges. A set $T \subseteq \Sigma$ is a transversal of $\mathcal{H}$ if for each $\varepsilon \in \Gamma$, $T \cap \varepsilon \neq \emptyset$. A transversal $T$ is minimal if no proper subset $T'$ of $T$ is a transversal. The set of the minimal transversals of an hypergraph $\mathcal{H}$ is noted $Tr(\mathcal{H})$. We formulate rewritings computation as a problem of finding hypergraph transversals. Given a query $Q$ and a set of class definitions $C = \{c_i \equiv \text{description}_i, i \in [1, n]\}$, the first step is to build an associated hypergraph $\mathcal{H}_{CQ}$ as follows: - each class $c_i$ in $C$ is associated to a vertex $V_{c_i}$ in the hypergraph $\mathcal{H}_{CQ}$. Thus $\Sigma = \{V_{c_i}, i \in [1, n]\}$. - each clause $A$ in the normal form description of the description of the query $Q$ is associated to an edge in the hypergraph $\mathcal{H}_{CQ}$. The edge is labelled by those classes that have in their RCFs a clause $A'$ that is equivalent to $A$. For the sake of clarity we introduce the following notation: for any set of vertices $X = \{V_{c_1}, \ldots, V_{c_q}\}$, subset of $\Sigma$, we use $E_X \equiv c_1 \cap \ldots \cap c_q$ to denote the class definition obtained from the conjunction of class names corresponding to the vertices in $X$. Inversely, for any rewriting $E \equiv c_1 \cap \ldots \cap c_q$, we use $X_E = \{V_{c_1}, \ldots, V_{c_q}\}$ to denote the set of vertices corresponding to the class names in $E$. Using lemmas 1 and 2 given below, we show that computing a best cover rewriting of $Q$ using $C$ (i.e., a rewriting that minimises the $Q_{\text{rest}}$) amounts to computing a transversal of $\mathcal{H}_{CQ}$ by considering only the non empty edges. Lemma 1 (characterisation of the minimal rest) Let $\mathcal{H}_{CQ} = (\Sigma, \Gamma)$ be the hypergraph built from a set of class definitions $C$ and a query $Q = A_1 \cap \ldots \cap A_k$ provided by its RCF. The minimal rest (i.e., the rest whose size is minimal) of rewriting $Q$ using $C$ is: $\text{Rest}_{\text{min}} \equiv A_{j_1} \cap \ldots \cap A_{j_l}, \forall j_i \in [1, k] \mid w_{A_{j_i}} = \emptyset$. Proof (sketch) Let $C = \{c_i \equiv \text{description}_i, i \in [1, n]\}$. First, to prove the existence of a rewriting $E$ of $Q$ using $C$ having such a rest, it is sufficient to consider $E$ as being the combination of all the classes in $C$, i.e., $E \equiv c_1 \cap \ldots \cap c_n$. Second, we show that $\text{Rest}_{\text{min}}$ has the minimal size. In the sequel, we use $\setminus$ (respectively, $\equiv$) to denote set difference of clause sets (respectively, set membership) where clauses are compared on the basis of the equivalence relation. We recall that, for any rewriting $E$, we have $\text{Rest}_E(Q) := Q \setminus \text{lcs}_C(Q, E)$. Assume that $Q$ and $\text{lcs}_C(Q, c_i), \forall i \in [1, n]$, are given by their RCFs. We have $A_{j_i} \equiv Q$ and $A_{j_i} \not\equiv \text{lcs}_C(Q, c_i)$ for all $j_i \in [1, k]$ such that $w_{A_{j_i}} = \emptyset$ (by construction of $H_{CQ}$). Then we can prove that for all $j_i \in [1, k]$ such that $w_{A_{j_i}} = \emptyset$ we have $A_{j_i} \not\equiv \text{lcs}_C(Q, E)$ (since $E$ is a conjunction of some classes $c_{j_i}$ and we use a description language. with structural subsumption\(^3\)). This implies that for all \( j_i \in [1, k] \) such that \( w_{A_{j_i}} = \emptyset \) we have \( A_{j_i} \subseteq Q \setminus \text{lcsc}(Q, E) \) and thus \( |\text{Rest}_{\text{min}}| \leq |\text{Rest}_E(Q)| \) for any rewriting \( E \) of \( Q \). From the previous lemma, we know that the minimal rest of a query \( Q \) using \( C \) is always unique and is equivalent to \( \text{Rest}_{\text{min}} \). Hence, a given rewriting \( E \) of \( Q \) using \( C \) is a best cover rewriting if and only if \( \text{rest}_E(Q) = \text{Rest}_{\text{min}} \). **Lemma 2 (characterisation of best cover rewritings)** Let \( \hat{\mathcal{H}}_{CQ} = (\Sigma, \Gamma') \) be the hypergraph built by removing from \( \mathcal{H}_{CQ} \) the empty edges. A rewriting \( E_{\text{min}} \equiv c_{i_1} \cap \ldots \cap c_{i_m}, \) where \( 1 \leq m \leq n \) and \( c_{i_j} \in C \) for \( 1 \leq j \leq m, \) is a best cover rewriting of \( Q \) using \( C \) iff \( X_{E_{\text{min}}} = \{ V_{c_{i_j}}, j \in [1, m] \} \) is a transversal of \( \hat{\mathcal{H}}_{CQ} \). **Proof** (sketch) The main steps of the proof are: - Lemma 1 \( \iff \forall w_{A_i} \in \hat{\mathcal{H}}_{CQ}, \) the corresponding clause \( A_i \not\subseteq Q \setminus \text{lcsc}(Q, E_{\text{min}}) \) - \( \forall w_{A_i} \in \hat{\mathcal{H}}_{CQ}, A_i \in \text{lcsc}(Q, E_{\text{min}}) \) - \( \forall w_{A_i} \in \hat{\mathcal{H}}_{CQ}, \exists c_{i_j} \text{ with } j \in [1, m] \mid A_i \in \text{lcsc}(Q, c_{i_j}) \) (since we use a description language with structural subsumption) - \( \forall w_{A_i} \in \hat{\mathcal{H}}_{CQ}, \exists V_{c_{i_j}} \in X_{E_{\text{min}}} \mid V_{c_{i_j}} \in w_{A_i} \) - \( X_{E_{\text{min}}} \) is a transversal of \( \hat{\mathcal{H}}_{CQ} \) (since \( X_{E_{\text{min}}} \) intersects each edge of \( \hat{\mathcal{H}}_{CQ} \)) This lemma characterises the best cover rewritings in terms of hypergraph transversals. The following characterisation of non redundant rewritings can be straightforwardly derived from lemma 2. **Lemma 3 (characterisation of non redundant rewritings)** A rewriting \( E \equiv c_{i_1} \cap \ldots \cap c_{i_m}, \) with \( 1 \leq m \leq n \) and \( c_{i_j} \in C \) for \( 1 \leq j \leq m, \) is a non redundant rewriting of \( Q \) using \( C \) iff \( X_E = \{ V_{c_{i_j}}, j \in [1, m] \} \) is a minimal transversal of \( \hat{\mathcal{H}}_{CQ} \). Now let us consider the characterisation of the best quality rewritings. Although, a detailed description of the used quality model is outside the scope of this paper, we assume \( l \) essential quality criteria (e.g., reliability, execution time) that are common to all community members: \[ q = \{ q_1, q_2, \ldots, q_l \} \] Therefore, we assume that for each potential member \( c_i, \) there is a quality vector \( q(c_i) \) which represents the goodness of selecting this member in relation to all essential quality criteria. This vector is defined as: --- \(^3\)In description languages with structural subsumption, a clause that appears in the RCF of a conjunction of some classes also appears in at least the RCF of one of these classes [22]. \[ q(c_i) = (q_1(c_i), q_2(c_i), \ldots, q_l(c_i)) \] (2) For simplicity, we assume that the value of each \( q_k(c_i) \) has been scaled to \([0, 1]\) and the higher the value is, the higher the quality is. It is worth noting that QoS criteria are not considered when selecting companion communities. In fact, each companion community will be in charge of selecting the best quality external members that are most likely relevant to answer the part of the query forwarded to it. Hence, in a given community, we assume that the outsourced categories have equal quality scores as stated below: \[ q_j(c_i) = 1 \quad \forall c_i \in \mathcal{V} \text{ and } \forall j \in [1, l]. \] (3) In this way, the outsourced categories and local members are treated uniformly with respect to QoS criteria. Finally, to be able to evaluate the quality of a given rewriting, we assume that there is a function \( f \), called optimisation function, that computes the quality of a set of member definitions (respectively, outsourced category definitions) based on their respective quality vectors. More precisely, given a rewriting \( E \equiv c_{i_1} \cap \ldots \cap c_{i_m} \), the quality of \( E \) is determined as follows: \[ \text{qual}(E) = f (q(c_{i_1}), \ldots, q(c_{i_m})) \] As before, we assume that the function \( f \) is scaled to \([0, 1]\) and the higher the value is, the higher the quality of the rewriting is. Let us now characterise the notion of quality of a rewriting in the context of hypergraphs. **Definition 7 (quality of a set of vertices)** Let \( X = \{V_{c_{i_1}}, \ldots, V_{c_{i_j}}\} \) be a set of vertices of the hypergraph \( \mathcal{H}_{\mathcal{CQ}} \). We define the notion of a quality of a set of vertices as: \( \text{qual}(X) = f (q(c_{i_1}), \ldots, q(c_{i_j})) \). Computing the best quality rewritings consist of determining, from the best cover rewritings, the ones that have the highest quality (See definition 5). In a hypergraph, this computation is characterised as follows. **Lemma 4 (characterisation of best quality rewritings)** A rewriting \( E \equiv c_{i_1} \cap \ldots \cap c_{i_m} \), with \( 1 \leq m \leq n \) and \( c_{i_j} \in \mathcal{C} \text{ for } 1 \leq j \leq m \), is a best quality rewriting of \( Q \) using \( \mathcal{C} \) iff: - \( X_E = \{V_{c_{i_j}}, j \in [1, m]\} \) is a transversal of \( \mathcal{C} \). - there doesn’t exist a transversal \( X_{E'} \) of \( \mathcal{C} \) such that \( \text{qual}(X_E) < \text{qual}(X_{E'}) \). Complexity Analysis. Based on known results in hypergraphs theory [10], we provide hereafter complexity analysis with respect to the computation of the proposed query rewritings. Let $\mathcal{C}$ be a set of class definitions and $Q$ be a community query. Let $n$ be the total number of class definitions in $\mathcal{C}$ and $m = |Q|$ be the size of a query $Q$. - A best cover rewriting of $Q$ using $\mathcal{C}$ can be found in time $O(m)$. - A non redundant rewriting can be found in time $O(mn)$. - Computing all the non redundant rewritings: From lemma 3, this problem amounts to computing the minimal transversals of a hypergraph. It is known that computing the minimal transversals of an hypergraph is inherently exponential since the size of the outputs (i.e., the number of the minimal transversals) is exponential in the input size [10]. However, whether there is an output-polynomial time algorithm (i.e., an algorithm that works in polynomial time if the number of minimal transversals is taken into account) for computing the minimal transversals of a hypergraph is still an open problem. In [11], it is shown that the generation of hypergraph transversals, and hence computation of minimal transversals, can be done in incremental subexponential time $k^{O(\log k)}$, where $k$ is the combined size of the input (the size of the hypergraph) and the output (i.e., the number of minimal transversals). To the best of our knowledge, this is the best theoretical upper time bound for computing minimal transversals of a hypergraph. - The general problem of computing a best quality rewriting is NP-hard. This result is based on a polynomial reduction of the NP-hard problem of finding a minimal cardinality transversal of a hypergraph [10] to a particular instance of the problem of computing the best quality rewritings. However, in some particular cases, depending on the characteristics of the optimisation function $f$, best quality rewritings can be computed efficiently. For example, in the case of additive functions, it suffices to select from each edge of the considered hypergraph the member with the highest quality score to obtain a best quality rewriting. Hence, in this case a best quality rewriting can be computed in time $O(mn)$. 4 Algorithm for Computing Best Quality Rewritings In this section, we describe an algorithm, called $\text{BestQRC}$, for computing best quality rewritings. Let $\mathcal{C} = \{c_i \equiv \text{description}_i, i \in [1, n]\}$ be a set of class definitions and $Q$ be a class definition that denotes a community query. The $\text{BestQRC}$ computes the best rewritings of the query $Q$ using $\mathcal{C}$ with respect to a given optimisation function $f$. We recall that the function $f$ is defined on a set of quality vectors $q(c_i)$, where $c_i$ denotes a class name. Each class name corresponds to a member definition name or to an outsourced category name. When designing this algorithm, we considered an optimisation function \( f \) that satisfies the following requirements: 1. **\( \text{(R1)} \)** \( f \) is strictly monotonic (i.e., \( Y \subset Y' \) implies that \( f(Y) > f(Y') \), where \( Y, Y' \) denote sets of quality vectors). This means that the higher the number of selected sources (i.e., local members and outsourced categories), the lower the quality of the rewriting. Consequently, in this case, the best quality rewritings should be selected among the non redundant rewritings. 2. **\( \text{(R2)} \)** \( f \) is a global optimisation function in the sense that it must be performed on the whole rewriting to get its quality score (i.e., \( f(Y) \) cannot be computed incrementally using a given intermediary result \( f(Y') \) where \( Y' \subset Y \)). These two requirements lead to a computation problem that is hard to deal with. Indeed, based on the analysis presented in the previous section and with respect to the requirement \( \text{(R2)} \), it can be shown that computing best quality non redundant rewritings in this case is an \textbf{NP-hard} problem. However, these two requirements also correspond to a likely realistic and desirable situations. Based on the analysis presented in the previous section, it can be shown that computing best quality non redundant rewritings can be mapped to finding the minimal transversals, with maximal quality, of the hypergraph \( \hat{\mathcal{H}}_{CQ} \). A classical algorithm for computing the minimal transversals of a hypergraph is presented in [6, 10]. Using this algorithm, computing the minimal transversals with the highest quality consists of (i) computing all the minimal transversals, and then (ii) choosing those transversals that have the highest quality. The \textit{BestQRC} algorithm presented below makes the following improvements (i.e., optimisations) with respect to the classical algorithm: 1. it reduces the number of candidates in the intermediary steps by generating only the minimal transversals, and 2. it uses, at the intermediary steps, a combinatorial optimisation technique, namely \textit{Branch-and-Bound} [17], in order to prune those candidate transversals which will not generate transversals with a maximal quality. The first optimisation generates minimal transversals at each iteration (line 10 of the algorithm). We use a necessary and sufficient condition (provided by Theorem 1 described below) to describe a pair \((X_i, c_j)\) that will generate a non minimal transversal at iteration \( i \), where \( X_i \) is a minimal transversal generated at iteration \( i-1 \) and \( c_j \) is a vertex of the \( i^{th} \) edge. \[ \text{The requirements (R1) and (R2) are inspired from a real life situation encountered during the application of our work in the context of an European project (cf. section 5).} \] Algorithm 1 BestQRC (skeleton) Require: a query $Q = A_1 \cap \ldots \cap A_k$ provided by its RCF and a community catalog $CAT = (CS, M)$, with $CS = (C, S, V)$. Ensure: The set $R(Q) = \{r(Q)\}$ of the best quality rewritings of $Q$ using $M \cup V$. 1: Let $C = M \cup V$. 2: Build the associated hypergraph $H_{CQ} = (\Sigma, \Gamma')$. 3: Compute $Q_{\text{rest}} = A_{j_1} \cap \ldots \cap A_{j_t}, \forall j_i \in [1,k] \mid w_{A_{j_i}} = \emptyset$. 4: Build the associated hypergraph $H_{CQ} = (\Sigma, \Gamma')$. 5: $R(Q) = \emptyset$ -- Initialisation of the best quality rewriting set. 6: $Tr = \emptyset$ -- Initialisation of the minimal transversal set. 7: Compute a minimal transversal $Y$ of $H_{CQ}$. 8: $\text{QualEval} \leftarrow \text{qual}(Y)$. -- Initialisation of QualEval. 9: for all edge $E \in \Gamma'$ do 10: $Tr \leftarrow$ the new generated set of the minimal transversals. -- Using Theorem 1. 11: Remove from $Tr$ the transversals whose quality is less than $\text{QualEval}$. 12: end for 13: for all $X = \{V_{e_1}, \ldots, V_{e_m}\} \in Tr$ such that $\text{qual}(X) = \text{QualEval}$ do 14: $Q_{\text{local}} = \{q_p, c_{ip}, p \in [1,m]\}$, where $q_p = A_{j_1} \cap \ldots \cap A_{j_t}, \forall j_i \in [1,k] \mid V_{e_p} \in w_{A_{j_i}}$, where $c_{ip} \in \emptyset$. 15: $Q_{\text{outsourced}} = \{q_p, c_{ip}, p \in [1,m]\}$ and $q_p = A_{j_1} \cap \ldots \cap A_{j_t}, \forall j_i \in [1,k] \mid V_{e_p} \in w_{A_{j_i}}$. 16: end for 17: $R(Q) = R(Q) \cup \{r(Q) = (Q_{\text{local}}, Q_{\text{outsourced}}, Q_{\text{rest}})\}$ 18: end for 19: return $R(Q)$ Theorem 1 Let $H$ be an hypergraph and its associated set of minimal transversals $Tr(H) = \{X_i \mid i \in \{1\ldots m\}\}$. Let $e = \{c_j \mid j \in \{1\ldots n\}\}$ be an extra edge of $H$. Let $H' = H \cup e$. $\forall i \in \{1\ldots m\}$ it holds: a) if $X_i \cap e \neq \emptyset$: \begin{align*} \forall j \in \{1\ldots n\}: - (c_j \notin X_i \cap e) & \to (X_i \cup \{c_j\} \mid \text{is a transversal of } H' \text{ that is not minimal}) - (c_j \in X_i \cap e) & \to (X_i \cup \{c_j\} = X_i \mid \text{is a minimal transversal of } H') \end{align*} b) if $X_i \cap e = \emptyset$: \begin{align*} \forall j \in \{1\ldots n\}: (X_i \cup \{c_j\} \mid \text{is a transversal of } H' \text{ that is not minimal}) & \leftrightarrow (\exists X_k \in Tr(H) \mid X_k \cap e = \{c_j\}) \text{ and } X_k \setminus \{c_j\} \subset X_i \end{align*} Proof a): straightforward. b): we recall (1) $X_i \cap e = \emptyset$, (2) $X_i \in Tr(H)$, (3) $H' = H \cup e$ and (4) $c_j \in e$. Let $(*) = X_i \cup \{c_j\}$ is a non minimal transversal of $H'$. Let $(**e) = \exists X_k \in Tr(H) \mid X_k \cap e = \{c_j\}$ and $X_k \setminus \{c_j\} \subset X_i$. Let’s note $Tr(H)$ the set of all transversals of $H$ (recall that $Tr(H)$ is the set of all minimal transversals of $H$). \((*) \Rightarrow \exists Y \mid Y \in Tr(\mathcal{H}') \quad \text{and} \quad Y \subset X_i \cup \{e_j\}\) \((1,2,3) \quad \exists \ Y \mid Y \in Tr(\mathcal{H}') \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \((1,2,3,4) \quad \exists \ Y \mid Y \in Tr(\mathcal{H}') \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \(\Leftrightarrow \exists \ Y \mid \forall e' \in \mathcal{H}', \ Y \cap e' \neq \emptyset \quad \text{and} \quad \forall c_y \in Y, \ Y \setminus \{c_y\} \notin tr(\mathcal{H}') \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \((2,3) \quad \exists \ Y \mid \forall e' \in \mathcal{H}', \ Y \cap e' \neq \emptyset \quad \text{and} \quad Y \setminus \{c_j\} \notin tr(\mathcal{H}) \quad \text{and} \quad \forall c_y \in Y, \ c_y \neq c_j, \ Y \setminus \{c_y\} \notin tr(\mathcal{H}) \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \((3,4) \quad \exists \ Y \mid \forall e' \in \mathcal{H}', \ Y \cap e' \neq \emptyset \quad \text{and} \quad Y \setminus \{c_j\} \notin tr(\mathcal{H}) \quad \text{and} \quad \forall c_y \in Y, \ c_y \neq c_j, \ Y \setminus \{c_y\} \notin tr(\mathcal{H}) \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \((3,4) \quad \exists \ Y \mid \forall e' \in \mathcal{H}', \ Y \cap e' \neq \emptyset \quad \text{and} \quad Y \setminus \{c_j\} \notin tr(\mathcal{H}) \quad \text{and} \quad \forall c_y \in Y, \ c_y \neq c_j, \ Y \setminus \{c_y\} \notin tr(\mathcal{H}) \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \(\Leftrightarrow \exists \ Y \mid Y \in Tr(\mathcal{H}) \quad \text{and} \quad c_j \in Y \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \((1,4) \quad \exists \ Y \mid Y \in Tr(\mathcal{H}) \quad \text{and} \quad Y \cap e = c_j \quad \text{and} \quad Y \setminus \{c_j\} \subset X_i\) \(\Leftrightarrow (**)\) The second optimisation consists of a Branch-and-Bound like enumeration of transversals. First, a simple heuristic is used to efficiently compute the quality of a good transversal (i.e., a transversal expected to have a high quality). The quality score is stored in the variable $BestQRC$ (line 8 of the algorithm). As we consider candidates in intermediate steps, any candidate transversal that has a quality score less than $QualEval$ (line 11) is eliminated from $Tr(\hat{NCQ})$. As the optimisation function $f$ is strictly monotonic, the quality score of considered candidate transversal cannot be better than that of already computed minimal transversal. At the end of the algorithm (lines 13 to 16), each computed minimal transversal $X \in Tr$ is translated into a rewriting $r(Q) = (Q_{local}, Q_{outsourced}, Q_{rest})$ which constitutes a best quality non redundant rewriting of the query $Q$ using $C$. The $Q_{rest}$ part of a query is computed at the beginning of the algorithm (line 3). The $Q_{local}$ (respectively, $Q_{outsourced}$) part of a given rewriting is computed as follows (lines 14 and 15): for vertices $V_{cip}$ in the transversal $X$, a pair $(q_{ip}, c_{ip})$ is created and added to the $Q_{local}$ part (respectively, the $Q_{outsourced}$ part) of the actual rewriting if $c_{ip}$ is a member definition name (respectively, outsourced category name). The associated query $q_{ip}$ consists of the conjunction of the clauses $A_j$ of the query $Q$ such that the corresponding hypergraph edge $w_{A_j}$ contains the vertices $V_{cip}$. 5 WS-CatalogNet Implementation Prototype. To evaluate our approach, we have implemented a prototype called WS-CatalogNet, which is a web service based environment for building catalog communities. This prototype consists of a set of integrated tools that allow catalog providers to create communities, member relationships (i.e., between a catalog provider and a community) and peer relationships (i.e., between communities). It also allows users to access the communities and submit queries to them. In WS-CatalogNet, both product catalogs and communities are represented as web services (cf. http://www.w3.org/2002/ws/). Overall, the prototype has been implemented using Java and WSDK 5.0\(^5\). A private UDDI\(^6\) registry (i.e. hosted by the WS-CatalogNet platform) is used as a repository for storing web services’ information. In UDDI registry, every web service is assigned to a tModel. A tModel provides a semantic classification of a service’s functionality and a formal description of its interfaces. We design specific tModels for product catalogs and for communities. In Table 1, we list few of the operations in the tModels\(^7\). When building a community, the community provider has to download two special classes named QueryProcessor and QueryRouter, which are provided by our system. The class QueryProcessor provides methods for processing query requests for each catalog community. It implements the $BestQRC$ rewriting al- \(^{5}\)IBM Web Services Development Kit 5.0 (www.alphaworks.ibm.com/tech/webservicestoolkit) \(^{6}\)Universal Description, Discovery and Integration \(^{7}\)For clarity reason, we omit detailed signature of the operations. Table 1: Main operations in tModel for members and communities <table> <thead> <tr> <th>Operations for</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td>Member M</td> <td></td> </tr> <tr> <td>Query()</td> <td>Invoked to query M</td> </tr> <tr> <td>GetInterface()</td> <td>Invoked to get categories and attributes of M</td> </tr> <tr> <td>Operations for</td> <td>Description</td> </tr> <tr> <td>Community C</td> <td></td> </tr> <tr> <td>Query()</td> <td>To query C</td> </tr> <tr> <td>GetInterface()</td> <td>To get the categories and attributes of C</td> </tr> <tr> <td>ForwardQuery()</td> <td>To forward queries to other communities</td> </tr> <tr> <td>AddPeer()</td> <td>To add a peer community</td> </tr> <tr> <td>RemovePeer()</td> <td>To remove a peer community</td> </tr> </tbody> </table> gorithm. Community metadata (i.e., descriptions of categories, members, mapping and forwarding policies) are stored as XML documents. The class QueryRouter provides methods for routing queries based on the forwarding policies and the peer mappings. Both classes are lightweight and the only infrastructures that they require are standard Java libraries, a JAXP-compliant XML parser, and a SOAP server. In order to have a better understanding of the issue of e-catalog selection, and validate our query rewriting approach, we used our prototype in the context of the MKBEEM project which aims at providing electronic marketplaces with intelligent, knowledge-based multi-lingual services. In this application, we used communities with approximately 300 categories and 50 e-catalogs. Indeed, this application has shown the effectiveness of the proposed query rewriting mechanism in two distinct end-user scenarios, namely: (i) business to consumer on-line sales, and (ii) Web based catalogs. **Preliminary Experiments.** In order to evaluate the performance of the BestQRC algorithm, we built a simulation testbed. In this testbed, we have implemented the two optimisations presented in section 4 as two separate options of the BestQRC algorithm, namely option Pers for the optimisation provided by the theorem 1 and option BnB for the optimisation that uses the Branch-and-Bound technique. We have then evaluated up to 6 versions of the BestQRC algorithm corresponding to different combinations of these optimisation options. The simulation testbed includes a tool that generates random XML-based test community schemas and queries. All experiments have been performed using a PC with a Pentium III 500 MHz and 384 Mo of RAM. We have considered three test scenarios with differences in the size of community schema, number of e-catalogs, and the query expressions (see Table 2). --- Table 2: Configurations <table> <thead> <tr> <th>Configurations</th> <th>Case 1</th> <th>Case 2</th> <th>Case 3</th> </tr> </thead> <tbody> <tr> <td>Number of defined categories in communities</td> <td>365</td> <td>1334</td> <td>3405</td> </tr> <tr> <td>Number of e-catalogs</td> <td>366</td> <td>660</td> <td>570</td> </tr> <tr> <td>Number of (atomic) clauses in the query</td> <td>6</td> <td>33</td> <td>12</td> </tr> </tbody> </table> We have run the 6 versions of the BestQRC algorithm on the test cases. The overall execution time results are given in Figure 3. This figure shows that for cases 1 and 3 (respectively, case 2), there is at least a version of the algorithm that runs in less than two seconds (respectively, in less than 30 seconds). Although Figure 3 shows that there are significant differences in performance between the different versions of the algorithm, in each case, there is at least one efficient version of the algorithm even when community schema is quite large (i.e., large number of categories). It should be noted that this preliminary experiment only concerns the performance of the rewriting algorithm. Ongoing experiments include performance and scalability studies that involve interactions (i.e., forwarding queries) in a network of communities formed via peer relationships. Note that versions 1 and 2 of the algorithm (respectively, 3 and 4) are similar as both run BestQRC without BnB, and what distinguishes 1 from 2 (respectively, 3 from 4) is the way the option BnB is implemented (BnB1 or BnB2). 6 Related Work and Conclusions In this section, we examine work done in e-catalogs integration. We also briefly discuss peer-to-peer data sharing approaches. Existing e-catalogs integration approaches typically rely on a global schema integration style [23]. For instance, [15] proposes an e-catalog integration approach, in which all categories of products are organised in a single graph structure and each leaf links to source catalog’s product attribute tree which represent local catalog’s product classification scheme. As mentioned before, a static approach, where the development of an integrated schema requires the understanding of both structure and semantics of all schemas of sources to be integrated, is hardly scalable because of the potentially large number and dynamic nature of available e-catalogs. Other approaches (e.g., [2]) focus on extracting structured and integrated schemas from documents that contain unstructured product description. Our work is not concerned with this issue. P2P computing is currently a very active research and development area. From information sharing point of view, the first generation of P2P systems (e.g., Gnutella, Napster) focused on files sharing (e.g., music, video clips). Query routing among peers in such approaches is discussed [9]. These systems support limited querying capabilities (e.g., keyword based search). Effective data sharing requires support for more structured querying capabilities to exploit the inherent semantics in data ([7, 20]). [16] proposes a super-peer based routing [24] in RDF-based P2P information sources. The proposed approach focuses on indexing RDF resources. Few approaches that leverage database-like information sharing and querying techniques in P2P environments emerged recently [1, 7]. PeerDB [18] uses a relational model to describe the schema of a peer data source. Relations and attributes are associated to keywords (i.e, synonyms of relation and attribute names). PeerDB uses an Information Retrieval (IR) approach for query routing to avoid the explicit specifications of mapping among peer schemas. The issue information space organisation is not considered. Piazza [12] considers the issue of schema mediation in P2P environments. It uses a relational model to describe peer schemas. It proposes a language for specifying mappings among peers. It also proposes a query reformulation algorithm for the proposed mediation framework. [20] proposes the notions of mutant query plan (MQP) and multi-hierarchy namespaces to support query processing in P2P environments. A MQP includes verbatim XML encoded data, references to actual resource locations (URL) and references to abstract resource names (URN). A peer can mutate an incoming MQP by either resolving URNs to URLs, or substituting a sub-plan with the evaluated XML encoded data. Our work provides complementary contributions to related work on data sharing and querying in peer-to-peer environment. We focus on providing support for achieving effective and efficient access to e-catalogs resident data. Since scalability is of great importance in e-catalog environments, the information space is organised in communities that are inter-related using peer relationships. The model that we use to describe community schemas relies on simple concepts (categories and attributes) that we found to be useful and commonly used to describe e-catalogs. content and capabilities. We consider different types of peer relationships between communities (i.e., companionship and similarity relationships). Such flexibility allows to establish different interaction types among communities. The specification of mappings in our approach combines: (i) IR style where no explicit mapping description is provided and (ii) full mapping description when it is possible or desired (e.g., in the case of companionship relationships). We formalised e-catalogs selection as a rewriting process for e-catalog communities. Query routing among peer communities is based on forward policies. We proposed a novel hypergraph-based algorithm to effectively select relevant e-catalogs for a given query. It should be noted that, the main approaches to rewriting using terminologies [4] are: the minimal rewriting problem [4] and query rewriting using views [13]. These approaches are based on (containment) subsumption or equivalence between a given query and its rewritings. In our approach, the proposed algorithm finds rewritings that ‘best match’ a given query with respect to a quality function, where the relationships between a query and its rewritings goes beyond containment or equivalence. We believe that there is a need for such a flexible query rewriting approach to cope with the high dynamicity and heterogeneity of the Web-based environments. References
Quantitative and localized spectroscopy for non-invasive bilirubinometry in neonates Bosschaart, N. Citation for published version (APA): CHAPTER 7 Improved acquisition speed in low-coherence spectroscopy by means of spectroscopic detection Low-coherence spectroscopy (LCS) is a promising technique for the non-invasive determination of blood composition, but its clinical utility may be limited by the speed of the current time domain detection scheme. In this Chapter, we investigate the possibility of spectroscopic detection in LCS (sdLCS), which has a theoretical sensitivity and/or speed advantage compared to time domain detection (tdLCS). Since sdLCS requires the acquisition of spectra with both high spectral, and high spatial resolution, a new method of acquisition and analysis was developed. In this Chapter, we validate our method computationally in a simulation and experimentally on a phantom with known optical properties. The attenuation, absorption and scattering coefficient spectra from the phantom that were measured by sdLCS agree well with the expected optical properties and are comparable to the measured optical properties by tdLCS. 7.1 Introduction In the previous Chapters 4 to 6, we have shown that low-coherence spectroscopy (LCS) can be used to measure local absorption, scattering and backscattering coefficient spectra in turbid media over almost the complete visible wavelength range (480 to 700 nm) [1-3]. By deriving hemoglobin concentrations from absorption coefficient spectra in the dermal microcirculation (Chapter 6), we showed that LCS is a promising technique for the localized quantification of tissue chromophore concentrations, which may lead to e.g. a non-invasive alternative for invasive blood sampling [3]. However, since most clinical applications require fast measurements for instantaneous diagnosis and the reduction of motion artifacts, the measurement speed of the current time domain LCS (tdLCS) system may limit its clinical applicability. From optical coherence tomography (OCT) studies, we know that spectroscopic detection allows for more sensitive measurements compared to time domain detection [4,5], which can be exchanged for higher acquisition speed at unaltered sensitivity. Therefore, in this Chapter we investigate the possibility for spectroscopic detection in LCS (sdLCS), focusing primarily on validating a new method of analysis that was developed for this purpose. Spectroscopic detection in OCT commonly involves spectrographs with high spectral resolution, a narrow wavelength range and a large number of pixels, resulting in large effective imaging depths (i.e. high maximal imaging depth and weak sensitivity roll-off in depth). Consequently, an A-scan of several mm can be recovered from a single back scattered spectrum, which is used for constructing an intensity image with high spatial resolution [4,5]. In LCS, we are mainly interested in the spectral content of the signal within a confined volume and hence, LCS requires both high spatial and sufficient spectral resolution (Chapter 4). In the case of spectroscopic detection, this can be achieved either by signal processing after acquisition [6], or by adjusting the signal acquisition itself. Since the latter has not been investigated before, we developed a new approach for signal acquisition in sdLCS. Our approach involves step-wise detection of local back scattered spectra with a spectrograph that has an effective imaging depth of only 9 μm in air. Thereby, we achieve both high spatial and sufficient spectral resolution (6 nm) and we maintain the advantage of focus tracking, as we had in our tdLCS system. The main challenge in step-wise spectroscopic detection with limited imaging depth involves removing the mirror image that originates from the complex ambiguity of the LCS signal. Methods for mirror image removal in OCT imaging commonly involve phase modulation and filtering of the modulated signal [8-10]. Similarly, our approach is to modulate the LCS signal, by using an oscillating mirror in the reference arm. Since the primary aim of this Chapter is to validate whether we can use this new approach for the determination of local absorption and scattering coefficient spectra, we will provide proof of principle with an on-the-shelf spectrograph (USB4000, Ocean Optics, USA). Only part of the feasible speed advantage is demonstrated, since the quantum efficiency and acquisition speed of this spectrograph are not optimized for sdLCS. After describing the theory behind sdLCS, we will validate our algorithm with a simulation of an sdLCS absorption measurement, while simulating the USB4000 as the detecting spectrograph. Subsequently, we experimentally demonstrate the ability of sdLCS to measure the attenuation, absorption and scattering coefficient spectra from a polystyrene-dye phantom, and we compare our results to a tdLCS measurement. 7.2 Theory The main difference between sdLCS and tdLCS is that the detector current $i_0$ is acquired as a function of wavelength $\lambda$ (e.g. by a spectrograph), instead of time by a photodiode (Chapters 4 to 6). Similar Eq. 4.1 for tdLCS, $i_0$ is modulated by the path length difference between the sample arm and the reference arm $\Delta L = 2(x_S - x_R)$, with sample arm length $x_S$ and reference arm length $x_R$. Hence, for sdLCS we can write: $$i_0 (k) \propto I_S (k) + I_R (k) + \sqrt{I_S (k) \cdot I_R (k)} \cdot 2\cos(k\Delta L) \quad (7.1)$$ where $k$ is the wavenumber ($k = 2\pi/\lambda$) and $I_S$ and $I_R$ are the signal intensities in the sample and reference arm, respectively. The two left terms of Eq. 7.1 denote the (‘DC’) non-modulated part of $i_0(k)$ and the right term denotes the (‘AC’) modulated part of $i_0(k)$, as has been illustrated in Figure 7.1a. Since $I_S$ and $I_R$ both originate from the source spectrum $S_0$, the modulation term in Eq. 7.1 can be written in terms of $S_0$. In case of a single reflector at path length $\ell$ (depth $\ell/2$), this results in: $$i_{0,\text{modulated}} (k) \propto \sqrt{\eta_S \cdot \eta_R \cdot e^{\mu t} \cdot S_0 (k)} \cdot 2\cos(k\Delta L) \quad (7.2)$$ with $\eta_S$ and $\eta_R = 1-\eta_S$ the fractions of $S_0$ that are guided towards the sample and reference arm, respectively, as determined by the splitting ratio of the beam splitter. The light originating from the sample arm is backscattered by a sample with an attenuation coefficient $\mu_t$ and hence, $I_S$ is attenuated by Beer’s law if the geometrical path length $\ell$ in the sample increases. In sdOCT, an A-scan (i.e. the backscattered intensity as a function of $d = \frac{\lambda}{2}\Delta L$) is obtained by Fourier transformation of $i_0(k)$: $$i_0 (\Delta L) = \left| \mathfrak{F} \{i_0 (k)\} \right|^2 \quad (7.3)$$ As illustrated in Figure 7.1b, the horizontal axis of $i_0(\Delta L)$ runs from $-\Delta L_{\text{max}}$ to $\Delta L_{\text{max}}$. For every $\Delta L$ a ‘mirror image’ is present at $-\Delta L$, i.e. both these path length differences result in the same modulation frequency on $i_0(k)$ (Eq. 7.1 and 7.2). The Nyquist criterion defines the maximal measurable path length difference $\Delta L_{\text{max}}$ or imaging depth $d_{\text{max}} = \frac{\lambda}{2}\Delta L_{\text{max}}$:} $$\Delta L_{\text{max}} = \frac{\pi}{\delta k} \quad (7.4)$$ in which $\delta k = (k_{\text{max}} - k_{\text{min}})/N_p$ depends entirely on the properties of the detecting spectrograph, which are the number of pixels $N_p$ and the minimal and maximal detectable wave number $k_{\text{min}}$ and $k_{\text{max}}$. The path length range over which $I(\Delta L)$ can be observed not only depends on $\Delta L_{\text{max}}$ but also on the sensitivity roll-off with $\Delta L$ of the spectrograph, caused by the finite spectrometer resolution [11]: in which Δk is the spectral resolution of the spectrograph. Since we use sdLCS for doing spectroscopy, we are interested in the spectrum $i_0(k)$ itself, rather than an A-scan as in sdOCT. However, Eq. 7.4 and 7.5 are important for sdLCS, since the $\Delta L_{\text{max}}$ and the signal roll-off determine the highest measurable modulation frequency in $i_0(k)$, and therefore the spatial resolution at which the spectrum $i_0(k)$ can be acquired. In contrast to sdOCT, sdLCS requires low values of $\Delta L_{\text{max}}$ and a fast sensitivity roll-off to obtain good spatial resolution for $i_0(k)$ (see Section 7.4). Similar to tdLCS, this introduces a trade-off between the spectral and spatial resolution of $i_0(k)$, because a fast sensitivity roll-off is accompanied by a low spectral resolution $\Delta k$ (Eq. 7.5). ### 7.2.1 Mirror image removal Merely acquiring $i_0(k)$ within a confined path length range does not provide us with a spectrum that we can use for the determination of $\mu_\nu$, since $i_0(k)$ contains unwanted DC (i.e. non-modulated components) and modulation components (Eq. 7.1 and 7.2). Moreover, the mirror image induces cross-talk between $i_0(\Delta L)$ and $i_0(-\Delta L)$ within the investigated path length range. This complex ambiguity can be removed by phase modulation and frequency domain filtering of the signal. Therefore, we modulate $i_0(k)$ using the oscillating mirror in the reference arm of our LCS system, which introduces a Doppler shift $f_D$ to the signal: $$f_D = \frac{2v_r}{\lambda} = \frac{v_r \cdot k}{\pi}$$ with $v_r$ the velocity of the reference mirror. Acquisition of N spectra $i_0(k)$ at every integration time $\tau$ of the spectrograph results in a dataset $i_0(k,t)$, as illustrated in Figure 7.1c. The phase of the modulation on $i_0(k,t)$ changes at every $\tau$, because the movement of the reference mirror induces a change in $\Delta L$ (vertical direction in Figure 7.1c). Figure 7.1d illustrates the time-modulation on $i_0(k,t)$ by $f_D$ for one wavelength (horizontal direction in Figure 7.1c). Since the sensitivity of the measurement is largest around $\Delta L = 0$ or ‘zero delay’ (Eq. 7.5), the range of $\Delta L$ is chosen such that it crosses zero delay at $\frac{1}{2}N\tau$ (Figure 7.1e). The integration time of the spectrograph should be chosen such that the time-modulation on $i_0(k,t)$ is adequately sampled. Hence the sampling frequency $f_s = 1/\tau$ needs to be larger than $2f_{D,\text{max}}$ (the largest value of $f_D$ within the investigated spectral range). For the integration time, this results in: $$\tau < \frac{\pi}{2v_r \cdot k_{\text{max}}} = \frac{\lambda_{\text{min}}}{4v_r}$$ with $k_{\text{max}}$ the largest wave number and $\lambda_{\text{min}}$ the shortest wavelength within the investigated spectral range. Fourier transformation on $i_0(k,t)$ with respect to $t$ provides the frequency content of the signal $i_0(k,f)$, which contains the modulation frequency $f_D$, its mirror image and a DC component (Figure 7.1f). By filtering out the part of $i_0(k,f)$ containing only the positive Spectroscopic LCS /g3 frequencies +f_D, the unwanted DC component and the negative frequencies –f_D are lost. Now that i_D(k) is confined both in amplitude and phase, the complex ambiguity and the mirror image in the path length domain (Figure 7.1b) are lost. Inverse Fourier transformation on the filtered i_D(k,f) with respect to f provides a smooth, non-modulated i_D(k,t) (Figure 7.1g), and averaging of i_D(k,t) over time results in the final spectrum S that we can use for the determination of μ_t (Figure 7.1h). Similar to tdLCS, a dataset S(ξ) is generated by step-wise alteration of the depth or geometrical round trip path length ξ in the sample around which i_D(κ) is acquired (Chapter 4). Hence, the advantage of focus tracking that we had in tdLCS can still be applied in sdLCS. 7.2.2 Sensitivity and/or speed advantage Our method for sdLCS provides a sensitivity advantage over tdLCS, which can be explained in terms of the signal to noise ratio (SNR). The SNR of any shot-noise limited LCS system is given by: \[ SNR = \frac{\epsilon \cdot S}{h \cdot \Delta f} \] in which \( \epsilon \) is the detection efficiency, \( h \) the photon energy and \( \Delta f \) the detection bandwidth of the system [5]. Using Eq. 4.8, we can write: \[ \Delta f = 2 f_{\text{scan}} d_{\text{scan}} \frac{\Delta \lambda}{\lambda_0}^2 \] with \( f_{\text{scan}} \) the scan rate and \( d_{\text{scan}} \) the scan length for the acquisition of one spectrum. For tdLCS, \( f_{\text{scan}}=2 f_R \) and \( d_{\text{scan}}=\Delta R \) (Chapter 4). For sdLCS, \( f_{\text{scan}}=1/\tau \) and \( d_{\text{scan}}=2 d_{\text{max}}=\Delta L_{\text{max}}=\lambda^2/(2 \Delta \lambda) \), if mirror image removal is applied. If we assume that in sdLCS, \( N_p \) pixels cover the bandwidth of the spectrum S, i.e. \( N_p \cdot \delta \lambda = \Delta \lambda \), then \( d_{\text{scan}} \) can be written into \( d_{\text{scan}}= N_p \lambda^2/2 \Delta \lambda \). Hence for sdLCS, \( \Delta f \) reduces to \( \Delta f=N_p/f_{\text{scan}} \). As a consequence, the SNR of a tdLCS system compares to the SNR of an sdLCS system as \( \frac{\text{SNR}_{\text{TD}}}{\text{SNR}_{\text{SD}}}= (\epsilon \cdot S)/(h \cdot \Delta f) = (\tau \cdot \epsilon \cdot S)/(h \cdot N_p) \). In conclusion, sdLCS is \( N_p \)-times more sensitive than tdLCS, provided that both systems have the same \( f_{\text{scan}} \), \( d_{\text{scan}} \) and \( \epsilon \). This sensitivity advantage can be exchanged for a speed advantage if \( f_{\text{scan}} \) is increased, i.e. an sdLCS system can measure \( N_p \)-times faster than a tdLCS system with equal sensitivity. A change in \( f_{\text{scan}} \) – i.e. between a ‘fast’ and a ‘slow’ LCS system – results in an SNR change with a factor \( \phi=\Delta f_{\text{slow}}/\Delta f_{\text{fast}}=(f_{\text{scan慢}},d_{\text{scan慢}})/(f_{\text{scan快}},d_{\text{scan快}}) \), which comprises \( \phi=2 f_R \tau (\Delta R/\Delta L_{\text{max}}) \) for a ‘fast’ system with the sdLCS settings (but without spectral detection) and a ‘slow’ system with the tdLCS settings. If in addition, spectral detection over \( N_p \) pixels is realized for the ‘fast’ system (as for our sdLCS system), the SNR will increase with a factor \( N_p \). As a consequence, the SNR_SD of an sdLCS system relates to the SNR_TD of a tdLCS system as: \[ \text{SNR}_{\text{SD}} = \phi \cdot N_p \cdot \frac{\epsilon_{\text{SD}}}{\epsilon_{\text{TD}}} \cdot \frac{\text{SNR}_{\text{TD}}}{\text{SNR}_{\text{TD}} = 2 f_R \cdot \tau \cdot N_p \cdot \frac{\epsilon_{\text{SD}}}{\epsilon_{\text{TD}}} \cdot \frac{\Delta R}{\Delta L_{\text{max}}} \cdot \text{SNR}_{\text{TD}}} \] which also considers a possible difference in detection efficiency between sdLCS and tdLCS. Figure 7.1: Signal acquisition and processing in SDLCS. See Section 7.2 for details. 7.3 Simulation In order to validate the data acquisition and analysis approach described in Section 7.2, we simulated an absorption measurement on a sample containing oxyhemoglobin [12]. Since scattering was neglected in the simulation, the attenuation coefficient $\mu_a$ in Eq. 7.2 can be simplified to the absorption coefficient $\mu_a$. The spectrum $S(\ell)$ was calculated at $\ell_1 = 2$ mm and $\ell_2 = 4$ mm inside the sample, corresponding to depths $d_1 = 1$ mm and at $d_2 = 2$ mm, respectively. The detecting spectrograph was simulated with the properties of the USB4000 ($\lambda_{\text{min}} = 345$ nm, $\lambda_{\text{max}} = 1042$ nm, $N_p = 3648$). The integration time was set at the minimal integration time of the USB4000 for these measurements, $\tau = 6$ ms. To meet the requirement in Eq. 7.7, the velocity of the reference mirror was set at $v_R = 6$ $\mu$m/s (frequency $f_R = 0.3$ Hz, amplitude $\Delta R = 20$ $\mu$m). The source spectrum $S_0$ was simulated as a Gaussian with center wavelength $\lambda_0 = 550$ nm and bandwidth $\lambda_{\text{FWHM}} = 140$ nm. The sample arm fraction was $\eta_s = 0.1$, resulting in a reference arm fraction of $\eta_R = 0.9$. A total number of $N = 125$ spectra was acquired over a time interval of $N \tau = 0.75$ s. The initial $\Delta L$ was set at -4.5 $\mu$m to achieve zero delay at $\frac{N}{2} \tau$. Figure 7.2 shows the result of this simulation. The $i_0(\lambda)$ at $\ell_1$ and $\ell_2$ show little influence of the sample’s absorption (Figure 7.2a). However, after phase modulation and frequency domain filtering of $i_0(\lambda)$, the resulting spectra $S$ at $\ell_1$ and $\ell_2$ clearly show the presence of the oxyhemoglobin absorption peaks (Figure 7.2b). Using Beer’s law, we obtain the absorption coefficient of the sample: $$\mu_a = \frac{1}{\frac{1}{2}(\ell_2 - \ell_1)} \ln \left( \frac{S(\ell_2)}{S(\ell_1)} \right)$$ (7.11) From Figure 7.2c, we can conclude that our method of data acquisition and analysis for sdLCS fully recovers the input $\mu_a$ of this simulation. ![Figure 7.2 Simulation of a $\mu_a$ measurement in sdLCS. a.) input spectra $i_0$ and b.) filtered spectra $S$ at path lengths $\ell_1$ and $\ell_2$ inside the sample. c.) input $\mu_a$ and recovered $\mu_a$ from Eq. 7.8.](image) 7.4 The path length window $\Delta \ell$ in sdLCS In sdLCS, the path length window over which $S(\ell)$ is acquired depends not only on the reference mirror scanning window in the medium ($\Delta \ell_R = 2\Delta R/n_g = 30 \, \mu m$ with the settings of Section 7.3 and group refractive index $n_g = 1.35$), but also on the path length window that is probed by the spectrograph $\Delta \ell_S$. The latter is a combination of $2\Delta L_{\text{max}}$ (due to mirror image removal) and the sensitivity roll-off with $\Delta L$ of the spectrograph. For the USB4000, we can calculate that $2\Delta L_{\text{max}} = 1880 \, \mu m$ (Eq. 7.4), but its sensitivity roll-off is not readily available. To determine the sensitivity roll-off of the USB4000, we both calculated (Eq. 7.5) and measured its roll-off function. Since the only unknown parameter in Eq. 7.5 is the spectral resolution $\Delta k$ (or $\Delta \lambda = 2\pi/\Delta k$), we measured $\Delta \lambda = 6 \, nm$ as the FWHM of a 543 nm and 633 nm HeNe laser line, projected on the spectrograph. This spectral resolution results in a theoretical sensitivity roll-off with a FWHM of 18 $\mu m$, indicated by the dotted line in Figure 7.3. We experimentally determined the sensitivity roll-off by measuring the reflection from a glass slide in the sample arm as a function of $\Delta L$ between the sample arm and the reference arm, using Eq. 7.3. The measured $i_{\text{in}}(\lambda)$ was resampled to a linear k-scale. The resulting sensitivity roll-off function is shown in Figure 7.3 and agrees very well with the theoretical function. Note that the width (FWHM) of the reflections at each value of $\Delta L$ is close to twice the coherence length ($2L_c = 3 \, \mu m$, Eq. 4.4) of the source (identical to the source in Chapters 4 to 6), and therefore agrees with the theoretical resolution for $\Delta L$. Since the FWHM of the sensitivity roll-off of the USB4000 is 18 $\mu m$, which is many times smaller than the $2\Delta L_{\text{max}}$ of 1880 $\mu m$, the path length window that is probed by the USB4000 can be approximated with $\Delta \ell_S = 18/n_g = 13 \, \mu m$. This $\Delta \ell_S$ probes a path length window around every path length $\ell$ in the reference mirror scanning window $\Delta \ell_R$. Hence, the full path length window that is probed in sdLCS is a convolution of $\Delta \ell_R$ with $\Delta \ell_S$, resulting in $\Delta \ell = \Delta \ell_R + \Delta \ell_S = 30 + 13 = 43 \, \mu m$ (inset of Figure 7.3). Figure 7.3 Theoretical and measured sensitivity roll-off of the USB4000. Inset: illustration of the path length window $\Delta \ell$ in sdLCS. 7.5 Experimental validation – Methods To experimentally validate our approach for sdLCS (Section 7.2), we measured attenuation spectra $\mu_t$ from 480 to 700 nm on a phantom with known absorption $\mu_a$ and scattering $\mu_s$ coefficient spectra and we separated the individual contributions of $\mu_a$ and $\mu_s$ from the measured $\mu_t$. In addition, we compared our sdLCS results to the results of a tdLCS measurement on the same phantom with the tdLCS system described in Chapters 4 to 6 (Figure 4.1) [1-3]. <table> <thead> <tr> <th>acquisition parameter</th> <th>sdLCS</th> <th>tdLCS</th> </tr> </thead> <tbody> <tr> <td>$\Delta \ell$</td> <td>43 $\mu$m</td> <td>44 $\mu$m</td> </tr> <tr> <td>$\Delta \lambda$</td> <td>6 nm (all $\lambda$)</td> <td>4 nm @ $\lambda$=480 nm</td> </tr> <tr> <td>$\nu_R$</td> <td>0.006 mm/s</td> <td>1.84 mm/s</td> </tr> <tr> <td>$f_R$</td> <td>0.3 Hz</td> <td>23 Hz</td> </tr> <tr> <td>$\Delta R$</td> <td>20 $\mu$m</td> <td>40 $\mu$m</td> </tr> <tr> <td>$N = #$ averages per $\ell$</td> <td>250</td> <td>250</td> </tr> <tr> <td>acquisition time of $S(\ell)$</td> <td>$N \tau = 1.5$ s</td> <td>$N/(2f_R) = 5.4$ s</td> </tr> </tbody> </table> 7.5.1 System and acquisition The sdLCS system described in this Chapter is identical to the tdLCS system in Chapters 4 to 6, except for the detection end of the system, which consists of a spectrograph rather than a photodiode/lock-in amplifier combination. Hence, the multimode detection fiber is connected to the detecting spectrograph (USB4000), from which the properties have been described in Section 7.3. For both the sdLCS and tdLCS measurements, we controlled $\ell$ ($\ell = 0 - 2000$ $\mu$m) by translating the reference mirror in steps of 27 $\mu$m. By translating the sample in the axial direction, focus tracking of the spot size ($r = 4.5$ $\mu$m) in the medium was achieved. At every $\ell$, back scattered power spectra $S(\ell)$ were obtained over a path length window in the medium of $\Delta \ell = 43$ $\mu$m for sdLCS (see Sections 7.2 and 7.4) and $\Delta \ell = 44$ $\mu$m for tdLCS (see Chapter 4). For both sdLCS and tdLCS, $S(\ell)$ was temporally averaged ($N = 250$ spectra per $\ell$) and corrected for the background (i.e. the LCS spectrum obtained from the non-scattering glass of the inner cuvette wall of the sample). The integration time for the sdLCS measurements was set at $\tau = 6$ ms and the reference mirror velocity at $v_R = 6$ $\mu$m/s, identical to the settings of the simulation (Section 7.3). The acquisition settings for the tdLCS measurements were identical to the settings in Chapters 4 to 6 [1-3]. For both sdLCS and tdLCS, the most important acquisition parameters have been summarized in Table 7.1. Note that the acquisition speed for one temporally averaged spectrum $S(\phi)$ is 3.6 times faster for sdLCS. Similar to the data analysis in Chapters 4 to 6, fitting the single exponential decay model $S(\phi) = \alpha \exp(-\mu_s \phi)$ (free running fit parameters $\alpha$ and $\mu_s$) to the sdLCS and tdLCS acquired $S(\phi)$ vs. $\phi$, results in a $\mu_s$ spectrum for both detection methods [1-3]. Uncertainties in $\alpha$ and $\mu_s$ are estimated by their 95% confidence intervals (c.i.). Since the spectral resolution in sdLCS ($\Delta \lambda = 6$ nm, Section 7.4) is higher than the pixel width of 0.2 nm, $S(\phi)$ was binned into wavelength regions of 6 nm for the sdLCS measurements. The values of $\mu_s$ and $\mu_t$ were obtained by fitting their individual contributions to the measured $\mu_t$, as described in Chapter 6.2.2 [3]. ### 7.5.2 Phantom We prepared one phantom, consisting of 0.096 vol% NIST-certified polystyrene spheres ($\phi \approx 602\pm6$ nm, Thermo Scientific, USA) and 10% magenta dye (Ecoline #337, Royal Talens, The Netherlands). The $\mu_s$ of the polystyrene spheres was calculated using Mie theory and integrated over the size distribution of the spheres ($2^{SD}$), as described in Chapter 5.2.4 [2]. The $\mu_s$ of the dye was determined in a separate transmission measurement on the dye only, as described in Chapter 4.3.2 [1]. For the tdLCS measurements, both reference spectra for $\mu_s$ and $\mu_t$ were convolved with a Lorentzian with a line width of 9 nm for adequate comparison to the LCS spectra that are Doppler broadened by Brownian motion (Chapters 4 to 6) [1-3]. For the sdLCS measurements, Brownian motion does not induce spectral broadening, because the Doppler shifted frequencies are still within the bounds of the frequency domain filter (Figure 7.1f). Since the reference spectrum of $\mu_s$ was obtained with the same spectral resolution as the LCS spectra, we did not broaden this spectrum. The reference spectrum of $\mu_s$ was convolved with a Lorentzian with a line width of 6 nm ($\Delta \lambda$ of the USB4000). ### 7.5.3 SNR comparison of sdLCS and tdLCS In order to compare the sensitivity of the current sdLCS system to the tdLCS system, we measured the SNR of the two detection methods, using a mirror in the sample arm. The optical powers in the sample and reference arm were equal and the acquisition settings in Table 7.1 were applied. For both sdLCS and tdLCS, the spectrally resolved SNR was determined from the measured spectrum $S$ using: $$\text{SNR} = 10 \cdot \log \left( \frac{S}{\text{var(noise)}} \right)$$ (7.12) and normalized to zero SNR. In Eq. 7.12 var(noise) denotes the variance of the noise floor in $S$ for both methods, determined in the wavelength region between 310 and 385 nm where no signal was expected. Based on Eq. 7.10, we can calculate the expected difference in SNR between both systems. The LCS spectrum covers approximately $N_p=1150$ pixels on the USB4000. Based on a maximum number of $4.10^9$ counts per photon and a pixel well depth of $1.10^5$ electrons, the quantum efficiency (QE = #electrons/photon) of the USB4000 is 2.5% at 600 nm. Using the photodiode response of 0.43 A/W (2001, New Focus, USA), we can calculate that our tdLCS detector has a QE of 89% at 600 nm. With τ=6 ms for our sdLCS system, the sensitivity advantage of the sdLCS measurements described in this Chapter reduces to 0.38. Hence, when using the USB4000 as a detector for sdLCS and the settings in Table 7.1, we can expect a decrease in SNR of 4.2 dB at 600 nm with respect to tdLCS. ![Figure 7.4 Comparison of an sdLCS measurement to a tdLCS measurement of \( \mu_t, \mu_a \) and \( \mu_s \) on a polystyrene-dye phantom.](image) ![Figure 7.5 Signal to noise ratio (SNR) in sdLCS and tdLCS. The investigated spectral range for the measurements in this Chapter runs from 480 to 700 nm (dashed lines).](image) 7.6 Experimental validation – Results Figure 7.4 shows the measured \( \mu_t \) spectra by sdLCS and tdLCS on the polystyrene-dye phantom. The \( \mu_t \) spectra from both detection methods agree within the estimated uncertainties (error bars) for nearly all wavelengths. Also the fits on \( \mu_t \) and the \( \mu_s \)-contributions to the fits agree well, and the \( \mu_s \)-contributions are in good agreement with the Mie calculated $\mu_s$. The fitted dye concentrations were $10.1 \pm 0.4\%$ for the sdLCS measurement and $9.5 \pm 0.4\%$ for the tdLCS measurement, which are both very close to the expected dye concentration of 10%. Figure 7.5 shows the measured SNR on a mirror. For both sdLCS and tdLCS, the SNR is maximal within the investigated spectral range of 480 to 700 nm. For the majority of wavelengths within this region, the SNR of tdLCS is larger than the SNR of sdLCS, except for the shortest wavelengths ($\lambda < 530$ nm). The decrease in SNR for sdLCS is close to the predicted value of $-4.2$ dB (Section 7.5.3). Note that the SNR value for tdLCS differs from the value given in Chapter 4 (112 dB) due to a difference in method of analysis. Whereas the SNR in Chapter 4 describes the minimally detectable signal with maximal amplification by the lock-in amplifier, the SNR in this Chapter is obtained with detection settings closer to actual measurements (e.g. with a backscatter coefficient larger than the minimal detectable reflectivity). However, the quantitative value of the SNR is of less importance here, since we primarily consider the differences in SNR in Figure 7.5 for the comparison between sdLCS and tdLCS. ![Figure 7.6 Simulation of the recovered spectrum $S$ for two integration times: $\tau = 0.06$ ms (with $v_x = 60$ $\mu$m/s) and $\tau = 6$ ms (with $v_x = 6$ $\mu$m/s).](image) ### 7.7 Discussion and conclusion In this Chapter, we demonstrated and validated a new detection method and analysis algorithm for spectroscopic detection in LCS. We showed that this method can be used for measuring local $\mu_v$, $\mu_a$ and $\mu_s$ spectra in turbid media. The results of the sdLCS phantom measurement agreed well with the expected optical properties of the phantom and were comparable to the measured optical properties by tdLCS (Figure 7.4). The reason to validate this new detection method, is its theoretical sensitivity advantage compared to time domain detection (Section 7.2.2). As a consequence, the acquisition speed of the measurement can be reduced with respect to time domain detection, without reducing the signal to noise ratio. The sdLCS system that was validated in this Chapter was more than three times faster than the tdLCS system, but not more sensitive (Figure 7.5). A sensitivity advantage for sdLCS could not be demonstrated, because the quantum efficiency of the USB4000 is not optimized for these experiments. However, if the quantum efficiency would be similar to that of our tdLCS detector, the sensitivity advantage would be $10\log(\phi_{N_p}) = 11$ dB at equal acquisition times for tdLCS and sdLCS (Section 7.5.3). Figure 7.5 shows a decrease in SNR of approximately 5 dB for sdLCS compared to tdLCS, which is slightly lower than the predicted decrease of 4.2 dB (Section 7.5.3) for these detection settings. The additional decrease in sensitivity can be explained by the relatively slow acquisition speed (167 Hz) of the USB4000. Slow acquisition speeds result in a decrease of the modulation depth in $i_0(\lambda)$ (‘fringe wash-out’), due to the reference mirror movement induced change of $\Delta L$ within the integration time. Hence, the sensitivity of our sdLCS measurements can be improved by increasing the integration time with respect to the velocity of the reference mirror. The effect of fringe wash-out on spectral amplitude has been illustrated in Figure 7.6. Comparable to the simulation in Section 7.3, Figure 7.6 shows the recovered spectra $S$ from a simulation without absorption using integration times of $\tau = 6$ ms and $\tau = 0.06$ ms and reference mirror velocities of 6 $\mu$m/s and 60 $\mu$m/s, respectively. Note that the integration times differ two orders of magnitude, whereas the reference mirror velocities only differ one order of magnitude. As a consequence, the spectrum $S$ for $\tau = 0.06$ ms has a higher amplitude ($\pm 15\%$, corresponding to 0.6 dB) and shows better agreement with the input sample arm spectrum ($\eta_0S_0$) than the spectrum $S$ for $\tau = 6$ ms. This simulation shows that, besides improvements on quantum efficiency, a faster spectrograph will further improve the performance of our sdLCS system. Since high quantum efficiency line scan cameras are available with line rates up to 140 kHz (e.g. the Basler Sprint spL4096-140km, Basler AG, Germany), enhanced sensitivity and/or acquisition speed are realizable for sdLCS. The only technique that is reported to have comparable performance to our sdLCS system in terms of localized measurements of optical properties, is dual band sOCT [6,7]. However, this method may not be as well applicable on thin layers or small tissue volumes as our LCS system [3], since the spatial dimensions of the largest of the dual bands in this method may extend the dimensions of the volume of interest. In addition, our sdLCS system has the unique advantage of focus tracking, which prevents unwanted signal attenuation and a decrease in sensitivity at larger path lengths in the medium. This facilitates the exact determination of $\mu_a$ and $\mu_s$ contributions to the measured $\mu_t$. In conclusion, the new approach for sdLCS demonstrated in this Chapter has high potential to improve the accuracy and speed of localized optical property measurements by LCS. Undoubtedly, this will lead to improved clinical utility of the technique, e.g. for the non-invasive determination of blood composition (hemoglobin/bilirubin concentration and oxygen saturation). References 12. Data tabulated from various sources compiled by S. Prahl, http://omlc.ogi.edu/spectra
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Everything’s Eventual One day, out of nowhere, I had a clear image of a young man pouring change into a sewer grating outside of the small suburban house in which he lived. I had nothing else, but the image was so clear—and so disturbingly odd—that I had to write a story about it. It came out smoothly and without a single hesitation, supporting my idea that stories are artifacts: not really made things which we create (and can take credit for), but preexisting objects which we dig up. I I’ve got a good job now, and no reason to feel glum. No more hanging out with the gumbyheads at the Supr Savr, policing up the Kart Korral and getting bothered by assholes like Skipper. Skipper’s munching the old dirt sandwich these days, but one thing I have learned in my nineteen years on this Planet Earth is don’t relax, there are Skippers everywhere. Ditto no more pulling pizza patrol on rainy nights, driving my old Ford with the bad muffler, freezing my ass off with the driver’s-side window down and a little Italian flag sticking out on a wire. Like somebody in Harkerville was going to salute. Pizza Roma. Quarter tips from people who don’t even see you, because most of their mind’s still on the TV football game. Driving for Pizza Roma was the lowest point, I think. Since then I've even had a ride in a private jet, so how could things be bad? "This is what comes of leaving school without a diploma," Ma would say during my Delivery Dan stint. And, "You've got this to look forward to for the rest of your life." Good old Ma. On and on, until I actually thought about writing her one of those special letters. As I say, that was the low point. You know what Mr. Sharpton told me that night in his car? "It's not just a job, Dink, it's a goddam adventure." And he was right. Whatever he might have been wrong about, he was right about that. I suppose you're wondering about the salary of this famous job. Well, I got to tell you, there's not much money in it. Might as well get that right up front. But a job isn't just about money, or getting ahead. That's what Mr. Sharpton told me. Mr. Sharpton said that a real job is about the fringe benefits. He said that's where the power is. Mr. Sharpton. I only saw him that once, sitting behind the wheel of his big old Mercedes-Benz, but sometimes once is enough. Take that any way you want. Any old way at all. II I've got a house, okay? My very own house. That's fringe benefit number one. I call Ma sometimes, ask how her bad leg is, shoot the shit, but I've never invited her over here, although Harkerville is only seventy or so miles away and I know she's practically busting a gut with curiosity. I don't even have to go see her unless I want to. Mostly I don't want to. If you knew my mother, you wouldn't want to, either. Sit there in that living room with her while she talks about all her relatives and whines about her puffy leg. Also I never noticed how much the house smelled of catshit until I got out of it. I'm never going to have a pet. Pets bite the big one. Mostly I just stay here. It's only got one bedroom, but it's still an excellent house. Eventual, as Pug used to say. He was the one guy at the Supr Savr I liked. When he wanted to say something was really EVERYTHING'S EVENTUAL good, Pug’d never say it was awesome, like most people do; he’d say it was eventual. How funny is that? The old Pugmeister. I wonder how he’s doing. Okay, I suppose. But I can’t call him and make sure. I can call my Ma, and I have an emergency number if anything ever goes wrong or if I think somebody’s getting nosy about what’s not their business, but I can’t buzz any of my old friends (as if any of them besides Pug gave Shit One about Dinky Earnshaw). Mr. Sharpton’s rules. But never mind that. Let’s go back to my house here in Columbia City. How many nineteen-year-old high-school dropouts do you know who have their own houses? Plus a new car? Only a Honda, true, but the first three numbers on the odometer are still zeroes, and that’s the important part. It has a CD/tape-player, and I don’t slide in behind the wheel wondering if the goddam thing’ll start, like I always did with the Ford, which Skipper used to make fun of. The Ass-holemobile, he called it. Why are there so many Skippers in the world? That’s what I really wonder about. I do get some money, by the way. More than enough to meet my needs. Check this out. I watch As the World Turns every day while I’m eating my lunch, and on Thursdays, about halfway through the show, I hear the clack of the mail-slot. I don’t do anything then, I’m not supposed to. Like Mr. Sharpton said, “Them’s the rules, Dink.” I just watch the rest of my show. The exciting stuff on the soaps always happens around the weekends—murders on Fridays, fucking on Mondays—but I watch right to the end every day, just the same. I’m especially careful to stay in the living room until the end on Thursdays. On Thursdays I don’t even go out to the kitchen for another glass of milk. When World is over, I turn off the TV for awhile—Oprah Winfrey comes on next, I hate her show, all that sitting-around-talking shit is for the Mas of the world—and go out to the front hall. Lying on the floor under the mail-slot, there’s always a plain white envelope, sealed. Nothing written on the front. Inside there’ll be either fourteen five-dollar bills or seven ten-dollar bills. That’s my money for the week. Here’s what I do with it. I go to the movies twice, always in the afternoon, when it's just $4.50. That's $9. On Saturday I fill up my Honda with gas, and that's usually about $7. I don't drive much. I'm not invested in it, as Pug would say. So now we're up to $16. I'll eat out maybe four times at Mickey D's, either at breakfast (Egg McMuffin, coffee, two hash browns) or at dinner (Quarter Pounder with Cheese, never mind that McSpecial shit, what dimbulb thought *those* sandwiches up). Once a week I put on chinos and a button-up shirt and see how the other half lives—have a fancy meal at a place like Adam's Ribs or the Chuck Wagon. All of that goes me about $25 and now we're up to $41. Then I might go by News Plus and buy a stroke book or two, nothing really kinky, just your usual like *Variations* or *Penthouse*. I have tried writing these mags down on DINKY'S DAYBOARD, but with no success. I can buy them myself, and they don't disappear on cleaning day or anything, but they don't *show up*, if you see what I'm getting at, like most other stuff does. I guess Mr. Sharpton's cleaners don't like to buy dirty stuff (pun). Also, I can't get to any of the sex stuff on the Internet. I have tried, but it's blocked out, somehow. Usually things like that are easy to deal with—you go under or around the roadblocks if you can't hack straight through—but this is different. Not to belabor the point, but I can't dial 900 numbers on the phone, either. The auto-dialer works, of course, and if I want to call somebody just at random, anywhere in the world, and shoot the shit with them for awhile, that's okay. That works. But the 900 numbers don't. You just get a busy. Probably just as well. In my experience, thinking about sex is like scratching poison ivy. You only spread it around. Besides, sex is no big deal, at least for me. It's there, but it isn't *eventual*. Still, considering what I'm doing, that little prudey streak is sort of weird. Almost funny . . . except I seem to have lost my sense of humor on the subject. A few others, as well. Oh well, back to the budget. If I get a *Variations*, that's four bucks and we're up to $45. Some of the money that's left I might use to buy a CD, although I don't have to, or a candy-bar or two (I know I shouldn't, because my complexion still blows dead rats, although I'm almost not a teenager any- EVERYTHING’S EVENTUAL more). I think of calling out for a pizza or for Chinese sometimes, but it’s against TransCorp’s rules. Also, I would feel weird doing it, like a member of the oppressing class. I have delivered pizza, remember. I know what a sucky job it is. Still, if I could order in, the pizza guy wouldn’t leave this house with a quarter tip. I’d lay five on him, watch his eyes light up. But you’re starting to see what I mean about not needing a lot of cash money, aren’t you? When Thursday morning rolls around again, I usually have at least eight bucks left, and sometimes it’s more like twenty. What I do with the coins is drop them down the storm-drain in front of my house. I am aware that this would freak the neighbors out if they saw me doing it (I’m a high-school dropout, but I didn’t leave because I was stupid, thank you very much), so I take out the blue plastic recycling basket with the newspapers in it (and sometimes with a Penthouse or Variations buried halfway down the stack, I don’t keep that shit around for long, who would), and while I’m putting it down on the curb, I open the hand with the change in it, and through the grate in the gutter it goes. Tinkle-tinkle-tinkle-splash. Like a magician’s trick. Now you see it, now you don’t. Someday that drain will get clogged up, they’ll send a guy down there and he’ll think he won the fucking lottery, unless there’s a flood or something that pushes all the change down to the waste treatment plant, or wherever it goes. By then I’ll be gone. I’m not going to spend my life in Columbia City, I can tell you that. I’m leaving, and soon. One way or the other. The currency is easier. I just poke it down the garbage disposal in the kitchen. Another magic trick, presto-change-o, money into lettuce. You probably think that’s very weird, running money through the sink-pig. I did, too, at first. But you get used to just about anything after you do it awhile, and besides, there’s always another seventy falling through the letter-slot. The rule is simple: no squirrelling it away. End the week broke. Besides, it’s not millions we’re talking about, only eight or ten bucks a week. Chump-change, really. 215 III DINKY’S DAYBOARD. That’s another fringe benefit. I write down whatever I want during the week, and I get everything I ask for (except sex-mags, as I told you). Maybe I’ll get bored with that eventually, but right now it’s like having Santa Claus all year round. Mostly what I write down is groceries, like anyone does on their kitchen chalkboard, but by no means is groceries all. I might, for instance, write down “New Bruce Willis Video” or “New Weezer CD” or something like that. A funny thing about that Weezer CD, since we’re on the subject. I happened to go into Toones Xpress one Friday after my movie was over (I always go to the show on Friday afternoons, even if there’s nothing I really want to see, because that’s when the cleaners come), just killing time inside because it was rainy and that squashed going to the park, and while I was looking at the new releases, this kid asks a clerk about the new Weezer CD. The clerk tells him it won’t be in for another ten days or so, but I’d had it since the Friday before. Fringe benefits, like I say. If I write down “sport shirt” on the DAYBOARD, there it is when I get back to the house on Friday night, always in one of the nice earth-tone colors I like. If I write down “new jeans” or “chinos,” I get those. All stuff from The Gap, which is where I’d go myself, if I had to do stuff like that. If I want a certain kind of after-shave lotion or cologne, I write the name on DINKY’S DAYBOARD and it’s on the bathroom counter when I get home. I don’t date, but I’m a fool for cologne. Go figure. Here’s something you’ll laugh at, I bet. Once I wrote down “Rembrandt Painting” on the DAYBOARD. Then I spent the afternoon at the movies and walking in the park, watching people making out and dogs catching Frisbees, thinking how eventual it would be if the cleaners actually brought me my own fucking Rembrandt. Think of it, a EVERYTHING’S EVENTUAL genuine Old Master on the wall of a house in the Sunset Knoll section of Columbia City. How eventual would that be? And it happened, in a manner of speaking. My Rembrandt was hung on the living room wall when I got home, over the sofa where the velvet clowns used to be. My heart was beating about two hundred a minute as I walked across the room toward it. When I got closer, I saw it was just a copy . . . you know, a reproduction. I was disappointed, but not very. I mean, it was a Rembrandt. Just not an original Rembrandt. Another time, I wrote “Autographed Photo of Nicole Kidman” on the dayboard. I think she’s the best-looking actress alive, she just gets me on so much. And when I got home that day, there was a publicity still of her on the fridge, held there by a couple of those little vegetable magnets. She was on her Moulin Rouge swing. And that time it was the real deal. I know because of the way it was signed: “To Dinky Earnshaw, with love & kisses from Nicole.” Oh, baby. Oh, honey. Tell you something, my friend—if I worked hard and really wanted it, there might be a real Rembrandt on my wall someday. Sure. In a job like this, there is nowhere to go but up. In a way, that’s the scary part. IV I never have to make grocery lists. The cleaners know what I like—Stouffer’s frozen dinners, especially that boil-in-the-bag stuff they call creamed chipped beef and Ma had always called shit on a shingle, frozen strawberries, whole milk, pre-formed hamburger patties that you just have to slap in a hot frying pan (I hate playing with raw meat), Dole puddings, the ones that come in plastic cups (bad for my complexion but I love em), ordinary food like that. If I want something special, I write it down on Dinky’s dayboard. Once I asked for a homemade apple pie, specifically not from the supermarket, and when I came back that night around the time it was getting dark, my pie was in the fridge with the rest of the week’s groceries. Only it wasn’t wrapped up, it was just sitting there on a blue plate. That’s how I knew it was homemade. I was a little hesitant about eating it at first, not knowing where it came from and all, and then I decided I was being stupid. A person doesn’t really know where supermarket food comes from, not really. I mean, we assume it’s okay because it’s wrapped up or in a can or “double-sealed for your protection,” but anyone could have been handling it with dirty fingers before it was double-sealed, or sneezing great big whoops of booger-breath on it, or even wiping their asses with it. I don’t mean to gross you out, but it’s true, isn’t it? The world is full of strangers, and a lot of them are “up to no good.” I have had personal experience of this, believe me. Anyway, I tried the pie and it was delicious. I ate half of it Friday night and the rest on Saturday morning, while I was running the numbers in Cheyenne, Wyoming. Most of Saturday night I spent on the toilet, shitting my guts out from all those apples, I guess, but I didn’t care. The pie was worth it. “Like mother used to make” is what people say, but it can’t be my mother they say it about. My Ma couldn’t fry Spam. V I never have to write down underwear on the dayboard. Every five weeks or so the old drawers disappear and there are brand-new Hanes Jockey-shorts in my bureau, four three-packs still in their plastic bags. Double-sealed for my protection, ha-ha. Toilet-paper, laundry soap, dishwasher soap, I never have to write any of that shit down. It just appears. Very eventual, don’t you think? EVERYTHING'S EVENTUAL VI I have never seen the cleaners, any more than I have ever seen the guy (or maybe it’s a gal) who delivers my seventy bucks every Thursday during As the World Turns. I never want to see them, either. I don’t need to, for one thing. For another, yes, okay, I’m afraid of them. Just like I was afraid of Mr. Sharpton in his big gray Mercedes on the night I went out to meet him. So sue me. I don’t eat lunch in my house on Fridays. I watch As the World Turns, then jump in my car and drive into town. I get a burger at Mickey D’s, then go to a movie, then to the park if the weather is good. I like the park. It’s a good place to think, and these days I’ve got an awful lot to think about. If the weather is bad, I go to the mall. Now that the days are beginning to shorten, I’m thinking about taking up bowling again. It’d be something to do on Friday afternoons, at least. I used to go now and then with Pug. I sort of miss Pug. I wish I could call him, just shoot the shit, tell him some of the stuff that’s been going on. Like about that guy Neff, for instance. Oh, well, spit in the ocean and see if it comes back. While I’m away, the cleaners are doing my house from wall to wall and top to bottom—wash the dishes (although I’m pretty good about that myself), wash the floors, wash the dirty clothes, change the sheets, put out fresh towels, restock the fridge, get any of the incidentals that are written on the dayboard. It’s like living in a hotel with the world’s most efficient (not to mention eventual) maid service. The one place they don’t mess around with much is the study off the dining room. I keep that room fairly dark, the shades always pulled, and they have never raised them to let in so much as a crack of daylight, like they do in the rest of the house. It never smells of Lemon Pledge in there, either, although every other room just about reeks of it on Friday nights. Sometimes it's so bad I have these sneezing fits. It's not an allergy; more like a nasal protest-demonstration. Someone vacuums the floor in there, and they empty the wastepaper basket, but no one has ever moved any of the papers that I keep on the desk, no matter how cluttered-up and junky-looking they are. Once I put a little piece of tape over where the drawer above the knee-hole opens, but it was still there, unbroken, when I got back home that night. I don't keep anything top secret in that drawer, you understand; I just wanted to know. Also, if the computer and modem are on when I leave, they're still on when I come back, the VDT showing one of the screen-saver programs (usually the one of the people doing stuff behind their blinds in this high-rise building, because that's my favorite). If my stuff was off when I left, it's off when I come back. They don't mess around in Dinky's study. Maybe the cleaners are a little afraid of me, too. VII I got the call that changed my life just when I thought the combination of Ma and delivering for Pizza Roma was going to drive me crazy. I know how melodramatic that sounds, but in this case, it's true. The call came on my night off. Ma was out with her girlfriends, playing Bingo at the Reservation, all of them smoking up a storm and no doubt laughing every time the caller pulled B-12 out of the hopper and said, "All right, ladies, it's time to take your vitamins." Me, I was watching a Clint Eastwood movie on TNT and wishing I was anywhere else on Planet Earth. Saskatchewan, even. The phone rings, and I think, oh good, it's Pug, gotta be, and so when I pick it up I say in my smoothest voice, "You have reached the Church of Any Eventuality, Harkerville branch, Reverend Dink speaking." "Hello, Mr. Earnshaw," a voice says back. It was one I'd never heard before, but it didn't seem the least put-out or puzzled by my bullshit. EVERYTHING’S EVENTUAL I was mortified enough for both of us, though. Have you ever noticed that when you do something like that on the phone—try to be cool right from the pickup—it’s never the person you expected on the other end? Once I heard about this girl who picked up the phone and said “Hi, it’s Helen, and I want you to fuck me raw” because she was sure it was her boyfriend, only it turned out to be her father. That story is probably made up, like the one about the alligators in the New York sewers (or the letters in *Penthouse*), but you get the point. “Oh, I’m sorry,” I say, too flustered to wonder how the owner of this strange voice knows that Reverend Dink is also Mr. Earnshaw, actual name Richard Ellery Earnshaw. “I thought you were someone else.” “I am someone else,” the voice says, and although I didn’t laugh then, I did later on. Mr. Sharpton was someone else, all right. Seriously, eventually someone else. “Can I help you?” I asked. “If you wanted my mother, I’ll have to take a message, because she’s—” “—out playing Bingo, I know. In any case, I want you, Mr. Earnshaw. I want to offer you a job.” For a moment I was too surprised to say anything. Then it hit me—some sort of phone-scam. “I got a job,” I go. “Sorry.” “Delivering pizza?” he says, sounding amused. “Well, I suppose. If you call that a job.” “Who are you, mister?” I ask. “My name is Sharpton. And now let me ‘cut through the bullshit,’ as you might say, Mr. Earnshaw. Dink? May I call you Dink?” “Sure,” I said. “Can I call you Sharpie?” “Call me whatever you want, just listen.” “I’m listening.” I was, too. Why not? The movie on the tube was *Coogan’s Bluff*, not one of Clint’s better efforts. “I want to make you the best job-offer you’ve ever had, and the best one you probably ever will have. It’s not just a job, Dink, it’s an adventure.” “Gee, where have I heard that before?” I had a bowl of popcorn in my lap, and I tossed a handful into my mouth. This was turning into fun, sort of. “Others promise; I deliver. But this is a discussion we must have face-to-face. Will you meet me?” “Are you a queer?” I asked. “No.” There was a touch of amusement in his voice. Just enough so that it was hard to disbelieve. And I was already in the hole, so to speak, from the smartass way I’d answered the phone. “My sexual orientation doesn’t come into this.” “Why’re you yanking my chain, then? I don’t know anybody who’d call me at nine-thirty in the fucking night and offer me a job.” “Do me a favor. Put the phone down and go look in your front hall.” Crazier and crazier. But what did I have to lose? I did what he said, and found an envelope lying there. Someone had poked it through the mail-slot while I was watching Clint Eastwood chase Don Stroud through Central Park. The first envelope of many, although of course I didn’t know that then. I tore it open, and seven ten-dollar bills fell out into my hand. Also a note. This can be the beginning of a great career! I went back into the living room, still looking at the money. Know how weirded-out I was? I almost sat on my bowl of popcorn. I saw it at the last second, set it aside, and plopped back on the couch. I picked up the phone, really sort of expecting Sharpton to be gone, but when I said hello, he answered. “What’s this all about?” I asked him. “What’s the seventy bucks for? I’m keeping it, but not because I think I owe you anything. I didn’t fucking ask for anything.” “The money is absolutely yours,” Sharpton says, “with not a string in the world attached. But I’ll let you in on a secret, Dink—a job isn’t just about money. A real job is about the fringe benefits. That’s where the power is.” “If you say so.” “I absolutely do. And all I ask is that you meet me and hear a little more. I’ll make you an offer that will change your life, if you take it. That will open the door to a new life, in fact. Once I’ve made that offer, you can ask all the questions you like. Although I must be honest and say you probably won’t get all the answers you’d like.” “And if I just decide to walk away?” “I’ll shake your hand, clap you on the back, and wish you good luck.” “When did you want to meet?” Part of me—most of me—still thought all this was a joke, but there was a minority opinion forming by then. There was the money, for one thing; two weeks’ worth of tips driving for Pizza Roma, and that’s if business was good. But mostly it was the way Sharpton talked. He sounded like he’d been to school . . . and I don’t mean at Sheep’s Rectum State College over in Van Drusen, either. And really, what harm could there be? Since Skipper’s accident, there was no one on Planet Earth who wanted to take after me in a way that was dangerous or painful. Well, Ma, I suppose, but her only weapon was her mouth . . . and she wasn’t into elaborate practical jokes. Also, I couldn’t see her parting with seventy dollars. Not when there was still a Bingo game in the vicinity. “Tonight,” he said. “Right now, in fact.” “All right, why not? Come on over. I guess if you can drop an envelope full of tens through the mail-slot, you don’t need me to give you the address.” “Not at your house. I’ll meet you in the Supr Savr parking lot.” My stomach dropped like an elevator with the cables cut, and the conversation stopped being the least bit funny. Maybe this was some kind of setup—something with cops in it, even. I told myself no one could know about Skipper, least of all the cops, but Jesus. There was the letter; Skipper could have left the letter lying around anywhere. Nothing in it anyone could make out (except for his sister’s name, but there are millions of Debbies in the world), no more than anyone could’ve made out the stuff I wrote on the sidewalk outside Mrs. Bukowski’s yard . . . or so I would have said before the goddam phone rang. But who could be absolutely sure? And you know what they say about a guilty conscience. I didn’t exactly feel guilty about Skipper, not then, but still . . . “The Supr Savr’s kind of a weird place for a job interview, don’t you think? Especially when it’s been closed since eight o’clock.” “That’s what makes it good, Dink. Privacy in a public place. I’ll park right by the Kart Korral. You’ll know the car—it’s a big gray Mercedes.” “I’ll know it because it’ll be the only one there,” I said, but he was already gone. I hung up and put the money in my pocket, almost without realizing I was doing it. I was sweating lightly all over my body. The voice on the phone wanted to meet me by the Kart Korral, where Skipper had so often teased me. Where he had once mashed my fingers between a couple of shopping carts, laughing when I screamed. That hurts the worst, getting your fingers mashed. Two of the nails had turned black and fallen off. That was when I’d made up my mind to try the letter. And the results had been unbelievable. Still, if Skipper Brannigan had a ghost, the Kart Korral was likely where it would hang out, looking for fresh victims to torture. The voice on the phone couldn’t have picked that place by accident. I tried to tell myself that was bullshit, that coincidences happened all the time, but I just didn’t believe it. Mr. Sharpton knew about Skipper. Somehow he knew. I was afraid to meet him, but I didn’t see what choice I had. If nothing else, I ought to find out how much he knew. And who he might tell. I got up, put on my coat (it was early spring then, and cold at night—it seems to me that it’s always cold at night in western Pennsylvania), started out the door, then went back and left a note for Ma. “Went out to see a couple of guys,” I wrote. “Will be back by midnight.” I intended to be back well before midnight, but that note seemed like a good idea. I wouldn’t let myself think too closely about why it seemed like a good idea, not then, but I can own up to it now: if something happened to me, something bad, I wanted to make sure Ma would call the police. VIII There are two kinds of scared—at least that’s my theory. There’s TV-scared, and there’s real-scared. I think we go through most of our lives only getting TV-scared. Like when we’re waiting for our blood-tests EVERYTHING'S EVENTUAL to come back from the doctor or when we're walking home from the library in the dark and thinking about bad guys in the bushes. We don't get real-scared about shit like that, because we know in our heart of hearts that the blood-tests will come back clean and there won't be any bad guys in the bushes. Why? Because stuff like that only happens to the people on TV. When I saw that big gray Mercedes, the only car in about an acre of empty parking lot, I got real-scared for the first time since the thing in the box-room with Skipper Brannigan. That time was the closest we ever came to really getting into it. Mr. Sharpton's ride was sitting under the light of the lot's yellow mercury-vapor lamps, a big old Krautmobile, at least a 450 and probably a 500, the kind of car that costs a hundred and twenty grand these days. Sitting there next to the Kart Korral (now almost empty for the night, all the carts except for one poor old three-wheeled cripple safely locked up inside) with its parking lights on and white exhaust drifting up into the air. Engine rumbling like a sleepy cat. I drove toward it, my heart pumping slow but hard and a taste like pennies in my throat. I wanted to just mat the accelerator of my Ford (which in those days always smelled like a pepperoni pizza) and get the hell out of there, but I couldn't get rid of the idea that the guy knew about Skipper. I could tell myself there was nothing to know, that Charles "Skipper" Brannigan had either had an accident or committed suicide, the cops weren't sure which (they couldn't have known him very well; if they had, they would have thrown the idea of suicide right out the window—guys like Skipper don't off themselves, not at the age of twenty-three they don't), but that didn't stop the voice from yammering away that I was in trouble, someone had figured it out, someone had gotten hold of the letter and figured it out. That voice didn't have logic on its side, but it didn't need to. It had good lungs and just out screamed logic. I parked beside the idling Mercedes and rolled my window down. At the same time, the driver's-side window of the Mercedes rolled down. We looked at each other, me and Mr. Sharpton, like a couple of old friends meeting at the Hi-Hat Drive-In. 225 I don’t remember much about him now. That’s weird, considering all the time I’ve spent thinking about him since, but it’s the truth. Only that he was thin, and that he was wearing a suit. A good one, I think, although judging stuff like that’s not my strong point. Still, the suit eased me a little. I guess that, unconsciously, I had this idea that a suit means business, and jeans and a tee-shirt means fuckery. “Hello, Dink,” he says. “I’m Mr. Sharpton. Come on in here and sit down.” “Why don’t we just stay the way we are?” I asked. “We can talk to each other through these windows. People do it all the time.” He only looked at me and said nothing. After a few seconds of that, I turned off the Ford and got out. I don’t know exactly why, but I did. I was more scared than ever, I can tell you that. Real-scared. Real as real as real. Maybe that was why he could get me to do what he wanted. I stood between Mr. Sharpton’s car and mine for a minute, looking at the Kart Korral and thinking about Skipper. He was tall, with this wavy blond hair he combed straight back from his forehead. He had pimples, and these red lips, like a girl wearing lipstick. “Hey Dinky, let’s see your dinky,” he’d say. Or “Hey Dinky, you want to suck my dinky?” You know, witty shit like that. Sometimes, when we were rounding up the carts, he’d chase me with one, nipping at my heels with it and going “Rmmmm! Rmmmmmm! Rmmmmmm!” like a fucking race-car. A couple of times he knocked me over. At dinner-break, if I had my food on my lap, he’d bump into me good and hard, see if he could knock something onto the floor. You know the kind of stuff I’m talking about, I’m sure. It was like he’d never gotten over those ideas of what’s funny to bored kids sitting in the back row of study hall. I had a ponytail at work, you had to wear your hair in a ponytail if you had it long, supermarket rules, and sometimes Skipper would come up behind me, grab the rubber band I used, and yank it out. Sometimes it would snarl in my hair and pull it. Sometimes it would break and snap against my neck. It got so I’d stick two or three extra rubber bands in my pants pocket before I left for work. I’d try not to EVERYTHING’S EVENTUAL think about why I was doing it, what I was putting up with. If I did, I’d probably start hating myself. Once I turned around on my heels when he did that, and he must have seen something on my face, because his teasing smile went away and another one came up where it had been. The teasing smile didn’t show his teeth, but the new one did. Out in the box-room, this was, where the north wall is always cold because it backs up against the meat-locker. He raised his hands and made them into fists. The other guys sat around with their lunches, looking at us, and I knew none of them would help. Not even Pug, who stands about five-feet-four anyway and weighs about a hundred and ten pounds. Skipper would have eaten him like candy, and Pug knew it. “Come on, assface,” Skipper said, smiling that smile. The broken rubber band he’d stripped out of my hair was dangling between two of his knuckles, hanging down like a little red lizard’s tongue. “Come on, you want to fight me? Come on, sure. I’ll fight you.” What I wanted was to ask why it had to be me he settled on, why it was me who somehow rubbed his fur wrong, why it had to be any guy. But he wouldn’t have had an answer. Guys like Skipper never do. They just want to knock your teeth out. So instead, I just sat back down and picked up my sandwich again. If I tried to fight Skipper, he’d likely put me in the hospital. I started to eat, although I wasn’t hungry anymore. He looked at me a second or two longer, and I thought he might go after me, anyway, but then he unrolled his fists. The broken rubber band dropped onto the floor beside a smashed lettuce-crate. “You waste,” Skipper said. “You fucking longhair hippie waste.” Then he walked away. It was only a few days later that he mashed my fingers between two of the carts in the Korral, and a few days after that Skipper was lying on satin in the Methodist Church with the organ playing. He brought it on himself, though. At least that’s what I thought then. “A little trip down Memory Lane?” Mr. Sharpton asked, and that jerked me back to the present. I was standing between his car and mine, standing by the Kart Korral where Skipper would never mash anyone else’s fingers. “I don’t know what you’re talking about.” “And it doesn’t matter. Hop in here, Dink, and let’s have a little talk.” I opened the door of the Mercedes and got in. Man, that smell. It’s leather, but not just leather. You know how, in Monopoly, there’s a Get-Out-of-Jail-Free card? When you’re rich enough to afford a car that smells like Mr. Sharpton’s gray Mercedes, you must have a Get-Out-of-Everything-Free card. I took a deep breath, held it, then let it out and said, “This is eventual.” Mr. Sharpton laughed, his clean-shaven cheeks gleaming in the dashboard lights. He didn’t ask what I meant; he knew. “Everything’s eventual, Dink,” he said. “Or can be, for the right person.” “You think so?” “Know so.” Not a shred of doubt in his voice. “I like your tie,” I said. I said it just to be saying something, but it was true, too. The tie wasn’t what I’d call eventual, but it was good. You know those ties that are printed all over with skulls or dinosaurs or little golf-clubs, stuff like that? Mr. Sharpton’s was printed all over with swords, a firm hand holding each one up. He laughed and ran a hand down it, kind of stroking it. “It’s my lucky tie,” he said. “When I put it on, I feel like King Arthur.” The smile died off his face, little by little, and I realized he wasn’t joking. “King Arthur, out gathering the best men there ever were. Knights to sit with him at the Round Table and remake the world.” That gave me a chill, but I tried not to show it. “What do you want with me, Art? Help you hunt for the Holy Grail, or whatever they call it?” “A tie doesn’t make a man a king,” he said. “I know that, in case you were wondering.” I shifted, feeling a little uncomfortable. “Hey, I wasn’t trying to put you down—” “It doesn’t matter, Dink. Really. The answer to your question is I’m two parts headhunter, two parts talent scout, and four parts walking, talking destiny. Cigarette?” EVERYTHING’S EVENTUAL “I don’t smoke.” “That’s good, you’ll live longer. Cigarettes are killers. Why else would people call them coffin-nails?” “You got me,” I said. “I hope so,” Mr. Sharpton said, lighting up. “I most sincerely hope so. You’re top-shelf goods, Dink. I doubt if you believe that, but it’s true.” “What’s this offer you were talking about?” “Tell me what happened to Skipper Brannigan.” Kabam, my worst fear come true. He couldn’t know, nobody could, but somehow he did. I only sat there feeling numb, my head pounding, my tongue stuck to the roof of my mouth like it was glued there. “Come on, tell me.” His voice seemed to be coming in from far away, like on a shortwave radio late at night. I got my tongue back where it belonged. It took an effort, but I managed. “I didn’t do anything.” My own voice seemed to be coming through on that same shitty shortwave band. “Skipper had an accident, that’s all. He was driving home and he went off the road. His car rolled over and went into Lockerby Stream. They found water in his lungs, so I guess he drowned, at least technically, but it was in the paper that he probably would have died, anyway. Most of his head got torn off in the rollover, or that’s what people say. And some people say it wasn’t an accident, that he killed himself, but I don’t buy that. Skipper was . . . he was getting too much fun out of life to kill himself.” “Yes. You were part of his fun, weren’t you?” I didn’t say anything, but my lips were trembling and there were tears in my eyes. Mr. Sharpton reached over and put his hand on my arm. It was the kind of thing you’d expect to get from an old guy like him, sitting with him in his big German car in a deserted parking lot, but I knew when he touched me that it wasn’t like that, he wasn’t hitting on me. It was good to be touched the way he touched me. Until then, I didn’t know how sad I was. Sometimes you don’t, because it’s just, I don’t know, all around. I put my head down. I didn’t start bawling or any- thing, but the tears went running down my cheeks. The swords on his tie doubled, then tripled—three for one, such a deal. “If you’re worried that I’m a cop, you can quit. And I gave you money—that screws up any sort of prosecution that might come out of this. But even if that wasn’t the case, no one would believe what really happened to young Mr. Brannigan, anyway. Not even if you confessed on nationwide TV. Would they?” “No,” I whispered. Then, louder: “I put up with a lot. Finally I couldn’t put up with any more. He made me, he brought it on himself.” “Tell me what happened,” Mr. Sharpton said. “I wrote him a letter,” I said. “A special letter.” “Yes, very special indeed. And what did you put in it so it could only work on him?” I knew what he meant, but there was more to it than that. When you personalized the letters, you increased their power. You made them lethal, not just dangerous. “His sister’s name,” I said. I think that was when I gave up completely. “His sister, Debbie.” IX I’ve always had something, some kind of deal, and I sort of knew it, but not how to use it or what its name was or what it meant. And I sort of knew I had to keep quiet about it, because other people didn’t have it. I thought they might put me in the circus if they found out. Or in jail. I remember once—vaguely, I might have been three or four, it’s one of my first memories—standing by this dirty window and looking out at the yard. There was a wood-chopping block and a mailbox with a red flag, so it must have been while we were at Aunt Mabel’s, out in the country. That was where we lived after my father ran off. Ma got a job in the Harkerville Fancy Bakery and we moved back to town later on, when I was five or so. We were living in town when I started EVERYTHING'S EVENTUAL school, I know that. Because of Mrs. Bukowski's dog, having to walk past that fucking canine cannibal five days a week. I'll never forget that dog. It was a boxer with a white ear. Talk about Memory Lane. Anyway, I was looking out and there were these flies buzzing around at the top of the window, you know how they do. I didn't like the sound, but I couldn't reach high enough, even with a rolled-up magazine, to swat them or make them go away. So instead of that, I made these two triangles on the windowpane, drawing in the dirt with the tip of my finger, and I made this other shape, a special circle-shape, to hold the triangles together. And as soon as I did that, as soon as I closed the circle, the flies—there were four or five of them—dropped dead on the windowsill. Big as jellybeans, they were—the black jellybeans that taste like licorice. I picked one up and looked at it, but it wasn't very interesting, so I dropped it on the floor and went on looking out the window. Stuff like that would happen from time to time, but never on purpose, never because I made it happen. The first time I remember doing something absolutely on purpose—before Skipper, I mean—was when I used my whatever-it-was on Mrs. Bukowski's dog. Mrs. Bukowski lived on the corner of our street, when we rented on Dugway Avenue. Her dog was mean and dangerous, every kid on the West Side was afraid of that white-eared fuck. She kept it tied in her side yard—hell, staked out in her side yard is more like it—and it barked at everyone who went by. Not harmless yapping, like some dogs do, but the kind that says If I could get you in here with me or get out there with you, I'd tear your balls off, Brewster. Once the dog did get loose, and it bit the paperboy. Anyone else's dog probably would have sniffed gas for that, but Mrs. Bukowski's son was the police chief, and he fixed it up, somehow. I hated that dog the way I hated Skipper. In a way, I suppose, it was Skipper. I had to go by Mrs. Bukowski's on my way to school unless I wanted to detour all the way around the block and get called a sissyboy, and I was terrified of the way that mutt would run to the end of its rope, barking so hard that foam would fly off its teeth and muzzle. Sometimes it hit the end of the rope so hard it'd go right off its feet, boi-yoi-yoinng, which might have looked funny to some people but never looked funny to me; I was just scared the rope (not a chain, but a plain old piece of rope) would break one day, and the dog would jump over the low picket fence between Mrs. Bukowski’s yard and Dugway Avenue, and it would rip my throat out. Then one day I woke up with an idea. I mean it was right there. I woke up with it the way some days I’d wake up with a great big throbbing boner. It was a Saturday, bright and early, and I didn’t have to go anywhere near Mrs. Bukowski’s if I didn’t want to, but that day I did want to. I got out of bed and threw on my clothes just as fast as I could. I did everything fast because I didn’t want to lose that idea. I would, too—I’d lose it the way you eventually lose the dreams you wake up with (or the boners you wake up with, if you want to be crude)—but right then I had the whole thing in my mind just as clear as a bell: words with triangles around them and curlicues over them, special circles to hold the whole shebang together . . . two or three of those, overlapping for extra strength. I just about flew through the living room (Ma was still sleeping, I could hear her snoring, and her pink bakery uniform was hung over the shower rod in the bathroom) and went into the kitchen. Ma had a little blackboard by the phone for numbers and reminders to herself—MA’S DAYBOARD instead of DINKY’S DAYBOARD, I guess you’d say—and I stopped just long enough to gleep the piece of pink chalk hanging on a string beside it. I put it in my pocket and went out the door. I remember what a beautiful morning that was, cool but not cold, the sky so blue it looked like someone had run it through the Happy Wheels Carwash, no one moving around much yet, most folks sleeping in a little, like everyone likes to do on Saturdays, if they can. Mrs. Bukowski’s dog wasn’t sleeping in. Fuck, no. That dog was a firm believer in rooty-tooty, do your duty. It saw me coming through the picket-fence and went charging to the end of its rope as hard as ever, maybe even harder, as if some part of its dim little doggy brain knew it was Saturday and I had no business being there. It hit the end of the rope, boi-yoi-yoinng, and went right over backward. It was up EVERYTHING'S EVENTUAL again in a second, though, standing at the end of its rope and barking in its chokey I'm-strangling-but-I-don't-care way. I suppose Mrs. Bukowski was used to that sound, maybe even liked it, but I've wondered since how the neighbors stood it. I paid no attention that day. I was too excited to be scared. I fished the chalk out of my pocket and dropped down on one knee. For one second I thought the whole works had gone out of my head, and that was bad. I felt despair and sadness trying to fill me up and I thought, No, don’t let it, don’t let it, Dinky, fight it. Write anything, even if it’s only FUCK MRS. BUKOWSKI’S DOG. But I didn’t write that. I drew this shape, I think it was a sankofite, instead. Some weird shape, but the right shape, because it unlocked everything else. My head flooded with stuff. It was wonderful, but at the same time it was really scary because there was so fucking much of it. For the next five minutes or so I knelt there on the sidewalk, sweating like a pig and writing like a mad fiend. I wrote words I’d never heard and drew shapes I’d never seen—shapes nobody had ever seen: not just sankofites but japps and fouders and mirks. I wrote and drew until I was pink dust halfway to my right elbow and Ma’s piece of chalk was nothing but a little pebble between my thumb and finger. Mrs. Bukowski’s dog didn’t die like the flies, it barked at me the whole time, and it probably drew back and ran out the length of its rope leash another time or two, but I didn’t notice. I was in this total frenzy. I could never describe it to you in a million years, but I bet it’s how great musicians like Mozart and Eric Clapton feel when they’re writing their music, or how painters feel when they’re getting their best work on canvas. If someone had come along, I would have ignored him. Shit, if Mrs. Bukowski’s dog had finally broken its rope, jumped the fence, and clamped down on my ass, I probably would have ignored that. It was eventual, man. It was so fucking eventual I can’t even tell you. No one did come, although a few cars went by and maybe the people in them wondered what that kid was doing, what he was drawing on the sidewalk, and Mrs. Bukowski’s dog went on barking. At the end, I realized I had to make it stronger, and the way to do that was to make it just for the dog. I didn’t know its name, so I printed \textit{boxer} with the last of the chalk, drew a circle around it, then made an arrow at the bottom of the circle, pointing to the rest. I felt dizzy and my head was throbbing, the way it does when you’ve just finished taking a super-hard test, or if you spend too long watching TV. I felt like I was going to be sick . . . but I still also felt totally eventual. I looked at the dog—it was still just as lively as ever, barking and kind of prancing on its back legs when it ran out of slack—but that didn’t bother me. I went back home feeling easy in my mind. I knew Mrs. Bukowski’s dog was toast. The same way, I bet, that a good painter knows when he’s painted a good picture, or a good writer knows when he’s written a good story. When it’s right, I think you just know. It sits there in your head and hums. Three days later the dog was eating the old dirt sandwich. I got the story from the best possible source when it comes to mean asshole dogs: the neighborhood mailman. Mr. Shermerhorn, his name was. Mr. Shermerhorn said Mrs. Bukowski’s boxer for some reason started running around the tree he was tied to, and when he got to the end of his rope (ha-ha, end of his rope), he couldn’t get back. Mrs. Bukowski was out shopping somewhere, so she was no help. When she got home, she found her dog lying at the base of the tree in her side yard, choked to death. The writing on the sidewalk stayed there for about a week; then it rained hard and afterward there was just a pink blur. But until it rained, it stayed pretty sharp. And while it was sharp, no one walked on it. I saw this for myself. People—kids walking to school, ladies walking downtown, Mr. Shermerhorn, the mailman—would just kind of veer around it. They didn’t even seem to know they were doing it. And nobody ever talked about it, either, like “What’s up with this weird shit on the sidewalk?” or “What do you suppose you call something that looks like that?” (A fouder, dimbulb.) It was as if they didn’t even see it was there. Except part of them must have. Why else would they have walked around it? EVERYTHING'S EVENTUAL X I didn’t tell Mr. Sharpton all that, but I told him what he wanted to know about Skipper. I had decided I could trust him. Maybe that secret part of me knew I could trust him, but I don’t think so. I think it was just the way he put his hand on my arm, like your Dad would. Not that I have a Dad, but I can imagine. Plus, it was like he said—even if he was a cop and arrested me, what judge and jury would believe Skipper Brannigan had driven his car off the road because of a letter I sent him? Especially one full of nonsense words and symbols made up by a pizza delivery-boy who had flunked high school geometry. Twice. When I was done, there was silence between us for a long time. At last Mr. Sharpton said, “He deserved it. You know that, don’t you?” And for some reason that did it. The dam burst and I cried like a baby. I must have cried for fifteen minutes or more. Mr. Sharpton put his arm around me and pulled me against his chest and I watered the lapel of his suit. If someone had driven by and seen us that way, they would have thought we were a couple of queers for sure, but nobody did. There was just him and me under the yellow mercury-vapor lamps, there by the Kart Korral. Yippy-ti-yi-yo, get along little shopping cart, Pug used to sing, for yew know Supr Savr will be yer new home. We’d laugh till we cried. At last I was able to turn off the waterworks. Mr. Sharpton handed me a hanky and I wiped my eyes with it. “How did you know?” I asked. My voice sounded all deep and weird, like a foghorn. “Once you were spotted, all it took was a little rudimentary detective work.” “Yeah, but how was I spotted?” “We have certain people—a dozen or so in all—who look for fellows and gals like you,” he said. “They can actually see fellows and gals like you, Dink, the way certain satellites in space can see nuclear piles and power-plants. You folks show up yellow. Like matchflames is how this one spotter described it to me.” He shook his head and gave a wry little smile. “I’d like to see something like that just once in my life. Or be able to do what you do. Of course, I’d also like to be given a day—just one would be fine—when I could paint like Picasso or write like Faulkner.” I gaped at him. “Is that true? There are people who can see—” “Yes. They’re our bloodhounds. They crisscross the country—and all the other countries—looking for that bright yellow glow. Looking for matchheads in the darkness. This particular young woman was on Route 90, actually headed for Pittsburgh to catch a plane home—to grab a little R-and-R—when she saw you. Or sensed you. Or whatever it is they do. The finders don’t really know themselves, any more than you really know what you did to Skipper. Do you?” “What—” He raised a hand. “I told you that you wouldn’t get all the answers you’d like—this is something you’ll have to decide on the basis of what you feel, not on what you know—but I can tell you a couple of things. To begin with, Dink, I work for an outfit called the Trans Corporation. Our job is getting rid of the world’s Skipper Brannigans—the big ones, the ones who do it on a grand scale. We have company headquarters in Chicago and a training center in Peoria . . . where you’ll spend a week, if you agree to my proposal.” I didn’t say anything then, but I knew already I was going to say yes to his proposal. Whatever it was, I was going to say yes. “You’re a tranny, my young friend. Better get used to the idea.” “What is it?” “A trait. There are folks in our organization who think of what you have . . . what you can do . . . as a talent or an ability or even a kind of glitch, but they’re wrong. Talent and ability are born of trait. Trait is general, talent and ability are specific.” “You’ll have to simplify that. I’m a high-school dropout, remember.” “I know,” he said. “I also know that you didn’t drop out because you were stupid; you dropped out because you didn’t fit. In that way, you are like every other tranny I’ve ever met.” He laughed in the sharp way people do when they’re not really amused. “All twenty-one of EVERYTHING'S EVENTUAL them. Now listen to me, and don’t play dumb. Creativity is like a hand at the end of your arm. But a hand has many fingers, doesn’t it?” “Well, at least five.” “Think of those fingers as abilities. A creative person may write, paint, sculpt, or think up math formulae; he or she might dance or sing or play a musical instrument. Those are the fingers, but creativity is the hand that gives them life. And just as all hands are basically the same—form follows function—all creative people are the same once you get down to the place where the fingers join. “Trans is also like a hand. Sometimes its fingers are called precognition, the ability to see the future. Sometimes they’re postcognition, the ability to see the past—we have a guy who knows who killed John F. Kennedy, and it wasn’t Lee Harvey Oswald; it was, in fact, a woman. There’s telepathy, pyrokinesis, telepathy, and who knows how many others. We don’t know, certainly; this is a new world, and we’ve barely begun to explore its first continent. But trans is different from creativity in one vital way: it’s much rarer. One person in eight hundred is what occupational psychologists call ‘gifted.’ We believe that there may only be one tranny in each eight million people.” That took my breath away—the idea that you might be one in eight million would take anybody’s breath away, right? “That’s about a hundred and twenty for every billion ordinary folks,” he said. “We think there may be no more than three thousand so-called trannies in the whole world. We’re finding them, one by one. It’s slow work. The sensing ability is fairly low-level, but we still only have a dozen or so finders, and each one takes a lot of training. This is a hard calling . . . but it’s also fabulously rewarding. We’re finding trannies and we’re putting them to work. That’s what we want to do with you, Dink: put you to work. We want to help you focus your talent, sharpen it, and use it for the betterment of all mankind. You won’t be able to see any of your old friends again—there’s no security risk on earth like an old friend, we’ve found—and there’s not a whole lot of cash in it, at least to begin with, but there’s a lot of satisfaction, and what I’m going to offer you is only the bottom rung of what may turn out to be a very high ladder.” STEPHEN KING “Don’t forget those fringe benefits,” I said, kind of raising my voice on the last word, turning it into a question, if he wanted to take it that way. He grinned and clapped me on the shoulder. “That’s right,” he said. “Those famous fringe benefits.” By then I was starting to get excited. My doubts weren’t gone, but they were melting away. “So tell me about it,” I said. My heart was beating hard, but it wasn’t fear. Not anymore. “Make me an offer I can’t refuse.” And that’s just what he did. XI Three weeks later I’m on an airplane for the first time in my life—and what a way to lose your cherry! The only passenger in a Lear 35, listening to Counting Crows pouring out of quad speakers with a Coke in one hand, watching as the altimeter climbs all the way to forty-two thousand feet. That’s over a mile higher than most commercial jetliners fly, the pilot told me. And a ride as smooth as the seat of a girl’s underpants. I spent a week in Peoria, and I was homesick. Really homesick. Surprised the shit out of me. There were a couple of nights when I even cried myself to sleep. I’m ashamed to say that, but I’ve been truthful so far, and don’t want to start lying or leaving things out now. Ma was the least of what I missed. You’d think we would have been close, as it was “us against the world,” in a manner of speaking, but my mother was never much for loving and comforting. She didn’t whip on my head or put out her cigarettes in my armpits or anything like that, but so what? I mean, big whoop. I’ve never had any kids, so I guess I can’t say for sure, but I somehow don’t think being a great parent is about the stuff you didn’t do to your rug monkeys. Ma was always more into her friends than me, and her weekly trip to the beauty shop, and Friday nights out at the Reservation. Her big ambition in life was to win a twenty-number Bingo and drive home in a brand-new Monte Carlo. I'm not sitting on the pity-pot, either. I'm just telling you how it was. Mr. Sharpton called Ma and told her that I'd been chosen to intern in the Trans Corporation's advanced computer training and placement project, a special deal for non-diploma kids with potential. The story was actually pretty believable. I was a shitty math student and froze up almost completely in classes like English, where you were supposed to talk, but I was always on good terms with the school computers. In fact, although I don't like to brag (and I never let any of the faculty in on this little secret), I could program rings around Mr. Jacobois and Mrs. Wilcoxen. I never cared much about computer games—they're strictly for dickbrains, in my humble opinion—but I could keyjack like a mad motherfucker. Pug used to drop by and watch me, sometimes. "I can't believe you," he said once. "Man, you got that thing smokin' and tokin.'" I shrugged. "Any fool can peel the Apple," I said. "It takes a real man to eat the core." So Ma believed it (she might have had a few more questions if she knew the Trans Corporation was flying me out to Illinois in a private jet, but she didn't), and I didn't miss her all that much. But I missed Pug, and John Cassiday, who was our other friend from our Supr Savr days. John plays bass in a punk band, wears a gold ring in his left eyebrow, and has just about every Subpop record ever made. He cried when Kurt Cobain ate the dirt sandwich. Didn't try to hide it or blame it on allergies, either. Just said, "I'm sad because Kurt died." John's eventual. And I missed Harkerville. Perverse but true. Being at the training center in Peoria was like being born again, somehow, and I guess being born always hurts. I thought I might meet some other people like me—if this was a book or a movie (or maybe just an episode of The X-Files), I would meet a cute chick with nifty little tits and the ability to shut doors from across the room—but that didn't happen. I'm pretty sure there were other trannies at Peoria when I was there, but Dr. Wentworth and the other folks running the place were careful to keep us separated. I once asked why, and got a runaround. That's when I started to realize that not everybody who had TRANSCORP printed on their shirts or walked around with TransCorp clipboards was my pal, or wanted to be my long-lost Dad. And it was about killing people; that's what I was training for. The folks in Peoria didn't talk about that all the time, but no one tried to sugarcoat it, either. I just had to remember the targets were bad guys, dictators and spies and serial killers, and as Mr. Sharpton said, people did it in wars all the time. Plus, it wasn't personal. No guns, no knives, no garrotes. I'd never get blood splashed on me. Like I told you, I never saw Mr. Sharpton again—at least not yet, I haven't—but I talked to him every day of the week I was in Peoria, and that eased the pain and strangeness considerably. Talking to him was like having someone put a cool cloth on your brow. He gave me his number the night we talked in his Mercedes, and told me to call him anytime. Even at three in the morning, if I was feeling upset. Once I did just that. I almost hung up on the second ring, because people may say call them anytime, even at three in the morning, but they don't really expect you to do it. But I hung in there. I was homesick, yeah, but it was more than that. The place wasn't what I had expected, exactly, and I wanted to tell Mr. Sharpton so. See how he took it, kind of. He answered on the third ring, and although he sounded sleepy (big surprise there, huh?), he didn't sound at all pissed. I told him that some of the stuff they were doing was quite weird. The test with all the flashing lights, for example. They said it was a test for epilepsy, but— "I went to sleep right in the middle of it," I said. "And when I woke up, I had a headache and it was hard to think. You know what I felt like? A file-cabinet after someone's been rummaging through it." "What's your point, Dink?" Mr. Sharpton asked. "I think they hypnotized me," I said. A brief pause. Then: "Maybe they did. Probably they did." "But why? Why would they? I'm doing everything they ask, so why would they want to hypnotize me?" EVERYTHING'S EVENTUAL “I don’t know all their routines and protocols, but I suspect they’re programming you. Putting a lot of housekeeping stuff on the lower levels of your mind so they won’t have to junk up the conscious part . . . and maybe screw up your special ability, while they’re at it. Really no different than programming a computer’s hard disk, and no more sinister.” “But you don’t know for sure?” “No—as I say, training and testing are not my purview. But I’ll make some calls, and Dr. Wentworth will talk to you. It may even be that an apology is due. If that’s the case, Dink, you may be sure that it will be tendered. Our trannies are too rare and too valuable to be upset needlessly. Now, is there anything else?” I thought about it, then said no. I thanked him and hung up. It had been on the tip of my tongue to tell him I thought I’d been drugged, as well . . . given some sort of mood-elevator to help me through the worst of my homesickness, but in the end I decided not to bother him. It was three in the morning, after all, and if they had been giving me anything, it was probably for my own good. XII Dr. Wentworth came to see me the next day—he was the Big Kahuna—and he did apologize. He was perfectly nice about it, but he had a look, I don’t know, like maybe Mr. Sharpton had called him about two minutes after I hung up and gave him a hot reaming. Dr. Wentworth took me for a walk on the back lawn—green and rolling and damned near perfect there at the end of spring—and said he was sorry for not keeping me “up to speed.” The epilepsy test really was an epilepsy test, he said (and a CAT-scan, too), but since it induced a hypnotic state in most subjects, they usually took advantage of it to give certain “baseline instructions.” In my case, they were instructions about the computer programs I’d be using in Columbia City. Dr. Wentworth asked me if I had any other questions. I lied and said no. STEPHEN KING You probably think that’s weird, but it’s not. I mean, I had a long and sucky school career which ended three months short of graduation. I had teachers I liked as well as teachers I hated, but never one I entirely trusted. I was the kind of kid who always sat in the back of the room if the teacher’s seating-chart wasn’t alphabetical, and never took part in class discussions. I mostly said “Huh?” when I was called on, and wild horses wouldn’t have dragged a question out of me. Mr. Sharpton was the only guy I ever met who was able to get into where I lived, and ole Doc Wentworth with his bald head and sharp eyes behind his little rimless glasses was no Mr. Sharpton. I could imagine pigs flying south for the winter before I could imagine opening up to that dude, let alone crying on his shoulder. And fuck, I didn’t know what else to ask, anyway. A lot of the time I liked it in Peoria, and I was excited by the prospects ahead—new job, new house, new town. People were great to me in Peoria. Even the food was great—meatloaf, fried chicken, milkshakes, everything I liked. Okay, I didn’t like the diagnostic tests, those boogersnouts you have to do with an IBM pencil, and sometimes I’d feel doopy, as if someone had put something in my mashed potatoes (or hyper, sometimes I’d feel that way, too), and there were other times—at least two—when I was pretty sure I’d been hypnotized again. But so what? I mean, was any of it a big deal after you’d been chased around a supermarket parking lot by a maniac who was laughing and making race-car noises and trying to run you over with a shopping cart? XIII I had one more talk on the phone with Mr. Sharpton that I suppose I should mention. That was just a day before my second airplane ride, the one that took me to Columbia City, where a guy was waiting with the keys to my new house. By then I knew about the cleaners, and the basic money-rule—start every week broke, end every week broke—and I knew who to call locally if I had a problem. (Any big problem and I call Mr. Sharpton, who is technically my “control.”) I had EVERYTHING'S EVENTUAL maps, a list of restaurants, directions to the cinema complex and the mall. I had a line on everything but the most important thing of all. “Mr. Sharpton, I don’t know what to do,” I said. I was talking to him on the phone just outside the caff. There was a phone in my room, but by then I was too nervous to sit down, let alone lie on my bed. If they were still putting shit in my food, it sure wasn’t working that day. “I can’t help you there, Dink,” he said, calm as ever. “So sorry, Cholly.” “What do you mean? You’ve got to help me! You recruited me, for jeepers’ sake!” “Let me give you a hypothetical case. Suppose I’m the President of a well-endowed college. Do you know what well-endowed means?” “Lots of bucks. I’m not stupid, I told you that.” “So you did—I apologize. Anyhow, let’s say that I, President Sharpton, use some of my school’s plentiful bucks to hire a great novelist as the writer-in-residence, or a great pianist to teach music. Would that entitle me to tell the novelist what to write, or the pianist what to compose?” “Probably not.” “Absolutely not. But let’s say it did. If I told the novelist, ‘Write a comedy about Betsy Ross screwing around with George Washington in Gay Paree,’ do you think he could do it?” I got laughing. I couldn’t help it. Mr. Sharpton’s just got a vibe about him, somehow. “Maybe,” I said. “Especially if you whipped a bonus on the guy.” “Okay, but even if he held his nose and cranked it out, it would likely be a very bad novel. Because creative people aren’t always in charge. And when they do their best work, they’re hardly ever in charge. They’re just sort of rolling along with their eyes shut, yelling Wheeeeee.” “What’s all that got to do with me? Listen, Mr. Sharpton—when I try to imagine what I’m going to do in Columbia City, all I see is a great big blank. Help people, you said. Make the world a better place. Get rid of the Skippers. All that sounds great, except I don’t know how to do it!” 243 "You will," he said. "When the time comes, you will." "You said Wentworth and his guys would focus my talent. Sharpen it. Mostly what they did was give me a bunch of stupid tests and make me feel like I was back in school. Is it all in my subconscious? Is it all on the hard disk?" "Trust me, Dink," he said. "Trust me, and trust yourself." So I did. I have. But just lately, things haven't been so good. Not so good at all. That goddam Neff—all the bad stuff started with him. I wish I'd never seen his picture. And if I had to see a picture, I wish I'd seen one where he wasn't smiling. XIV My first week in Columbia City, I did nothing. I mean absolutely zilch. I didn't even go to the movies. When the cleaners came, I just went to the park and sat on a bench and felt like the whole world was watching me. When it came time to get rid of my extra money on Thursday, I ended up shredding better than fifty dollars in the garbage disposal. And doing that was new to me then, remember. Talk about feeling weird—man, you don't have a clue. While I was standing there, listening to the motor under the sink grinding away, I kept thinking about Ma. If Ma had been there to see what I was doing, she would have probably run me through with a butcher-knife to make me stop. That was a dozen twenty-number Bingo games (or two dozen cover-alls) going straight down the kitchen pig. I slept like shit that week. Every now and then I'd go to the little study—I didn't want to, but my feet would drag me there. Like they say murderers always return to the scenes of their crimes, I guess. Anyway, I'd stand there in the doorway and look at the dark computer screen, at the Global Village modem, and I'd just sweat with guilt and embarrassment and fear. Even the way the desk was so neat and clean, without a single paper or note on it, made me sweat. I could just about hear the walls muttering stuff like "Nah, EVERYTHING’S EVENTUAL nothing going on in here” and “Who’s this turkey, the cable-installer?” I had nightmares. In one of them, the doorbell rings and when I open it, Mr. Sharpton’s there. He’s got a pair of handcuffs. “Put out your wrists, Dink,” he says. “We thought you were a tranny, but obviously we were wrong. Sometimes it happens.” “No, I am,” I say. “I am a tranny, I just need a little more time to get acclimated. I’ve never been away from home before, remember.” “You’ve had five years,” he goes. I’m stunned. I can’t believe it. But part of me knows it’s true. It feels like days, but it’s really been five fucking years, and I haven’t turned on the computer in the little study a single time. If not for the cleaners, the desk it sits on would be six inches deep in dust. “Hold out your hands, Dink. Stop making this hard on both of us.” “I won’t,” I say, “and you can’t make me.” He looks behind him then, and who should come up the steps but Skipper Brannigan. He is wearing his red nylon tunic, only now TRANSCORP is sewn on it instead of SUPR SAVR. He looks pale but otherwise okay. Not dead is what I mean. “You thought you did something to me, but you didn’t,” Skipper says. “You couldn’t do anything to anyone. You’re just a hippie waste.” “I’m going to put these cuffs on him,” Mr. Sharpton says to Skipper. “If he gives me any trouble, run him over with a shopping cart.” “Totally eventual,” Skipper says, and I wake up half out of my bed and on the floor, screaming. XV Then, about ten days after I moved in, I had another kind of dream. I don’t remember what it was, but it must have been a good one, because when I woke up, I was smiling. I could feel it on my face, a big, happy smile. It was like when I woke up with the idea about Mrs. Bukowski’s dog. Almost exactly like that. I pulled on a pair of jeans and went into the study. I turned on the computer and opened the window marked TOOLS. There was a program in there called DINKY’s NOTEBOOK. I went right to it, and all my symbols were there—circles, triangles, japps, mirks, rhomboids, bews, smims, fouders, hundreds more. Thousands more. Maybe millions more. It’s sort of like Mr. Sharpton said: a new world, and I’m on the coastline of the first continent. All I know is that all at once it was there for me, I had a great big Macintosh computer to work with instead of a little piece of pink chalk, and all I had to do was type the words for the symbols and the symbols would appear. I was jacked to the max. I mean my God. It was like a river of fire burning in the middle of my head. I wrote, I called up symbols, I used the mouse to drag everything where it was supposed to be. And when it was done, I had a letter. One of the special letters. But a letter to who? A letter to where? Then I realized it didn’t matter. Make a few minor customizing touches, and there were many people the letter could go to . . . although this one had been written for a man rather than a woman. I don’t know how I knew that; I just did. I decided to start with Cincinnati, only because Cincinnati was the first city to come into my mind. It could as easily have been Zurich, Switzerland, or Waterville, Maine. I tried to open a TOOLS program titled DINKYMAIL. Before the computer would let me in there, it prompted me to wake up my modem. Once the modem was running, the computer wanted a 312 area code. 312’s Chicago, and I imagine that, as far as the phone company is concerned, my compu-calls all come from TransCorp’s headquarters. I didn’t care one way or another; that was their business. I had found my business and was taking care of it. With the modem awake and linked to Chicago, the computer flashed DINKYMAIL READY. I clicked on LOCALE. I’d been in the study almost three hours by then, with only one break to take a quick piss, and I could smell EVERYTHING'S EVENTUAL myself, sweating and stinking like a monkey in a greenhouse. I didn’t mind. I liked the smell. I was having the time of my life. I was fucking delirious. I typed CINCINNATI and hit EXECUTE. NO LISTINGS CINCINNATI the computer said. Okay, not a problem. Try Columbus—closer to home, anyway. And yes, folks! We have a Bingo. TWO LISTINGS COLUMBUS There were two telephone numbers. I clicked on the top one, curious and a little afraid of what might pop out. But it wasn’t a dossier, a profile, or—God forbid—a photograph. There was one single word: MUFFIN. Say what? But then I knew. Muffin was Mr. Columbus’s pet. Very likely a cat. I called up my special letter again, transposed two symbols and deleted a third. Then I added MUFFIN to the top, with an arrow pointing down. There. Perfect. Did I wonder who Muffin’s owner was, or what he had done to warrant TransCorp’s attention, or exactly what was going to happen to him? I did not. The idea that my conditioning at Peoria might have been partially responsible for this disinterest never crossed my mind, either. I was doing my thing, that was all. Just doing my thing, and as happy as a clam at high tide. I called the number on the screen. I had the computer’s speaker on, but there was no hello, only the screechy mating-call of another computer. Just as well, really. Life’s easier when you subtract the human element. Then it’s like that movie, Twelve O’Clock High, cruising over Berlin in your trusty B-25, looking through your trusty Norden 247 STEPHEN KING bombsight and waiting for just the right moment to push your trusty button. You might see smokestacks, or factory roofs, but no people. The guys who dropped the bombs from their B-25s didn’t have to hear the screams of mothers whose children had just been reduced to guts, and I didn’t even have to hear anyone say hello. A very good deal. After a little bit, I turned off the speaker anyway. I found it distracting. MODEM FOUND, the computer flashed, and then SEARCH FOR E-MAIL ADDRESS Y/N. I typed Y and waited. This time the wait was longer. I think the computer was going back to Chicago again, and getting what it needed to unlock the e-mail address of Mr. Columbus. Still, it was less than thirty seconds before the computer was right back at me with E-MAIL ADDRESS FOUND SEND DINKYMAIL Y/N. I typed Y with absolutely no hesitation. The computer flashed SENDING DINKYMAIL and then DINKYMAIL SENT. That was all. No fireworks. I wonder what happened to Muffin, though. You know. After. EVERYTHING’S EVENTUAL XVI That night I called Mr. Sharpton and said, “I’m working.” “That’s good, Dink. Great news. Feel better?” Calm as ever. Mr. Sharpton is like the weather in Tahiti. “Yeah,” I said. The fact was, I felt blissful. It was the best day of my life. Doubts or no doubts, worries or no worries, I still say that. The most eventual day of my life. It was like a river of fire in my head, a fucking river of fire, can you get that? “Do you feel better, Mr. Sharpton? Relieved?” “I’m happy for you, but I can’t say I’m relieved, because—” “—you were never worried in the first place.” “Got it in one,” he said. “Everything’s eventual, in other words.” He laughed at that. He always laughs when I say that. “That’s right, Dink. Everything’s eventual.” “Mr. Sharpton?” “Yes?” “E-mail’s not exactly private, you know. Anybody who’s really dedicated can hack into it.” “Part of what you send is a suggestion that the recipient delete the message from all files, is it not?” “Yes, but I can’t absolutely guarantee that he’ll do it. Or she.” “Even if they don’t, nothing can happen to someone else who chances on such a message, am I correct? Because it’s . . . personalized.” “Well, it might give someone a headache, but that would be about all.” “And the communication itself would look like so much gibberish.” “Or a code.” He laughed heartily at that. “Let them try to break it, Dinky, eh? Just let them try!” I sighed. “I suppose.” “Let’s discuss something more important, Dink . . . how did it feel?” “Fucking wonderful.” “Good. Don’t question wonder, Dink. Don’t ever question wonder.” And he hung up. XVII Sometimes I have to send actual letters—print out the stuff I whomp up in Dinky’s Notebook, stick it in an envelope, lick stamps, and mail it off to somebody somewhere. Professor Ann Tevitch, University of New Mexico at Las Cruces. Mr. Andrew Neff, c/o The New York Post, New York, New York. Billy Unger, General Delivery, Stovington, Vermont. Only names, but they were still more upsetting than the phone numbers. More personal than the phone numbers. It was like seeing faces swim up at you for a second inside your Norden bombsight. I mean, what a freak-out, right? You’re up there at twenty-five thousand feet, no faces allowed up there, but sometimes one shows up for a second or two, just the same. I wondered how a University Professor could get along without a modem (or a guy whose address was a fucking New York newspaper, for that matter), but I never wondered too much. I didn’t have to. We live in a modern world, but letters don’t have to be sent by computer, after all. There’s still snail-mail. And the stuff I really needed was always in the database. The fact that Unger had a 1957 Thunderbird, for instance. Or that Ann Tevitch had a loved one—perhaps her husband, perhaps her son, perhaps her father—named Simon. And people like Tevitch and Unger were exceptions. Most of the folks I reach out and touch are like that first one in Columbus—fully equipped for the twenty-first century. SENDING DINKYMAIL, DINKYMAIL SENT, velly good, so long, Cholly. I could have gone on like that for a long time, maybe forever—browsing the database (there’s no schedule to follow, no list of primary cities and targets; I’m completely on my own . . . unless all that shit is also in my subconscious, down there on the hard disk), going EVERYTHING'S EVENTUAL to afternoon movies, enjoying the Ma-less silence of my little house, and dreaming of my next step up the ladder, except I woke up feeling horny one day. I worked for an hour or so, browsing around in Australia, but it was no good—my dick kept trespassing on my brain, so to speak. I shut off the computer and went down to News Plus to see if I could find a magazine featuring pretty ladies in frothy lingerie. As I got there, a guy was coming out, reading the Columbus Dispatch. I never read the paper myself. Why bother? It’s the same old shit day in and day out, dictators beating the ching-chong out of people weaker than they are, men in uniforms beating the ching-chong out of soccer balls or footballs, politicians kissing babies and kissing ass. Mostly stories about the Skipper Brannigans of the world, in other words. And I wouldn’t have seen this story even if I’d happened to look at the newspaper display rack once I got inside, because it was on the bottom half of the front page, below the fold. But this fucking dimbulb comes out with the paper hanging open and his face buried inside it. In the lower right corner was a picture of a white-haired guy smoking a pipe and smiling. He looked like a good-humored fuck, probably Irish, eyes all crinkled up and these white bushy eyebrows. And the headline over the photo—not a big one, but you could read it—said NEFF SUICIDE STILL PUZZLES, GRIEVES COLLEAGUES For a second or two I thought I’d just skip News Plus that day, I didn’t feel like ladies in lingerie after all, maybe I’d just go home and take a nap. If I went in, I’d probably pick up a copy of the Dispatch, wouldn’t be able to help myself, and I wasn’t sure I wanted to know any more about that Irish-looking guy than I already did . . . which was nothing at all, as you can fucking believe I hastened to tell myself. Neff couldn’t be that weird a name anyway, only four letters, not like Shittendookus or Horecake, there must be thousands of Neffs, if you’re talking coast to coast. This one didn’t have to be the Neff I knew about, the one who loved Frank Sinatra records. It would be better, in any case, to just leave and come back tomorrow. Tomorrow the picture of that guy with the pipe would be gone. Tomorrow somebody else’s picture would be there, on the lower right corner of page one. People always dying, right? People who aren’t superstars or anything, just famous enough to get their pictures down there in the lower right corner of page one. And sometimes people were puzzled about it, the way folks back home in Harkerville had been puzzled about Skipper’s death—no alcohol in his blood, clear night, dry road, not the suicidal type. The world is full of mysteries like that, though, and sometimes it’s best not to solve them. Sometimes the solutions aren’t, you know, too eventual. But willpower has never been my strong point. I can’t always keep away from the chocolate, even though I know my skin doesn’t like it, and I couldn’t keep away from the Columbus Dispatch that day. I went on inside and bought one. I started home, then had a funny thought. The funny thought was that I didn’t want a newspaper with Andrew Neff’s picture on the front page going out with my trash. The trash pick-up guys came in a city truck, surely they didn’t—couldn’t—have anything to do with TransCorp, but . . . There was this show me and Pug used to watch one summer back when we were little kids. Golden Years, it was called. You probably don’t remember it. Anyway, there was a guy on that show who used to say “Perfect paranoia is perfect awareness.” It was like his motto. And I sort of believe that. Anyway, I went to the park instead of back home. I sat on a bench and read the story, and when I was done, I stuck the paper in a park trashbarrel. I didn’t even like doing that, but hey—if Mr. Sharpton has got a guy following me around and checking on every little thing I throw away, I’m fucked up the wazoo no matter what. There was no doubt that Andrew Neff, age sixty-two, a columnist for the Post since 1970, had committed suicide. He took a bunch of pills that probably would have done the trick, then climbed into his bathtub, put a plastic bag over his head, and rounded the evening off by slitting his wrists. There was a man totally dedicated to avoiding counselling. He left no note, though, and the autopsy showed no signs of dis- EVERYTHING'S EVENTUAL ease. His colleagues scoffed at the idea of Alzheimer's, or even early senility. "He was the sharpest guy I've ever known, right up to the day he died," a guy named Pete Hamill said. "He could have gone on Challenge Jeopardy! and run both boards. I have no idea why Andy did such a thing." Hamill went on to say that one of Neff's "charming oddities" was his complete refusal to participate in the computer revolution. No modems for him, no laptop word processor, no handheld spell-checker from Franklin Electronic Publishers. He didn't even have a CD player in his apartment, Hamill said; Neff claimed, perhaps only half-joking, that compact discs were the Devil's work. He loved the Chairman of the Board, but only on vinyl. This guy Hamill and several others said Neff was unfailingly cheerful, right up to the afternoon he filed his last column, went home, drank a glass of wine, and then demo'd himself. One of the Post's chatter columnists, Liz Smith, said she'd shared a piece of pie with him just before he left on that last day, and Neff had seemed "a trifle distracted, but otherwise fine." Distracted, sure. With a headful of fouders, bews, and smims, you'd be distracted, too. Neff, the piece went on, had been something of an anomaly on the Post, which sticks up for the more conservative view of life—I guess they don't come right out and recommend electrocuting welfare recipients after three years and still no job, but they do hint that it's always an option. I guess Neff was the house liberal. He wrote a column called "Eneff Is Eneff," and in it he talked about changing the way New York treated single teen mothers, suggested that maybe abortion wasn't always murder, argued that the low-income housing in the outer boroughs was a self-perpetuating hate machine. Near the end of his life, he'd been writing columns about the size of the military, and asking why we as a country felt we had to keep pouring on the bucks when there was, essentially, no one left to fight except for the terrorists. He said we'd do better to spend that money creating jobs. And Post readers, who would have crucified anyone else saying stuff like that, pretty much loved it when Neff laid it down. Because 253 he was funny. Because he was charming. Maybe because he was Irish and had kissed the Blarney Stone. That was about all. I started home. Somewhere along the way I took a detour, though, and ended up walking all over downtown. I zigged and zagged, walking down boulevards and cutting through parking lots, all the time thinking about Andrew Neff climbing into his bathtub and putting a Baggie over his head. A big one, a gallon-size, keeps all your leftovers supermarket-fresh. He was funny. He was charming. And I had killed him. Neff had opened my letter and it had gotten into his head, somehow. Judging by what I’d read in the paper, the special words and symbols took maybe three days to fuck him up enough to swallow the pills and climb into the tub. _He deserved it._ That’s what Mr. Sharpton said about Skipper, and maybe he was right . . . that time. But did Neff deserve it? Was there shit about him I didn’t know, did he maybe like little girls in the wrong way or push dope or go after people too weak to fight back, like Skipper had gone after me with the shopping cart? _We want to help you use your talent for the betterment of all mankind,_ Mr. Sharpton said, and surely that didn’t mean making a guy off himself because he thought the Defense Department was spending too much money on smart-bombs. Paranoid shit like that is strictly for movies starring Steven Seagal and Jean-Claude Van Damme. Then I had a bad idea—a scary idea. Maybe TransCorp didn’t want him dead because he wrote that stuff. Maybe they wanted him dead because people—the wrong people—were starting to _think_ about what he wrote. “That’s crazy,” I said, right out loud, and a woman looking into the window of Columbia City-Oh So Pretty turned around and gave me the old fish-eye. I ended up at the public library around two o’clock, with my legs aching and my head throbbing. I kept seeing that guy in the bathtub, with his wrinkled old man’s tits and white chest-hair, his nice EVERYTHING'S EVENTUAL smile gone, replaced by this vague Planet X look. I kept seeing him putting a Baggie over his head, humming a Sinatra tune ("My Way," maybe) as he snugged it down tight, then peered through it the way you'd peer through a cloudy window, so he could see to slit the veins in his wrists. I didn't want to see that stuff, but I couldn't stop. My bombsight had turned into a telescope. They had a computer room in the library, and you could get on the Internet at a very reasonable cost. I had to get a library card, too, but that was okay. A library card is good to have, you can never have too much ID. It took me only three bucks' worth of time to find Ann Tevitch and call up the report of her death. The story started, I saw with a sinking sensation, in the bottom right-hand corner of page one, The Official Dead Folks' Nook, and then jumped to the obituary page. Professor Tevitch had been a pretty lady, blond, thirty-seven. In the photo she was holding her glasses in her hand, as if she wanted people to know she wore them . . . but as if she'd wanted people to see what pretty eyes she had, too. That made me feel sad and guilty. Her death was startlingly like Skipper's—coming home from her office at UNM just after dark, maybe hurrying a little because it was her turn to make supper, but what the hell, good driving conditions and great visibility. Her car—vanity license plate DNA FAN, I happened to know—had veered off the road, overturned, and landed in a drywash. She was still alive when someone spotted the headlights and found her, but there had never been any real hope; her injuries were too grave. There was no alcohol in her system and her marriage was in good shape (no kids, at least, thank God for small favors), so the idea of suicide was farfetched. She had been looking forward to the future, had even talked about getting a computer to celebrate a new research grant. She'd refused to own a PC since 1988 or so; had lost some valuable data in one when it locked up, and had distrusted them ever since. She would use her department's equipment when she absolutely had to, but that was all. The coroner's verdict had been accidental death. STEPHEN KING Professor Ann Tevitch, a clinical biologist, had been in the forefront of West Coast AIDS research. Another scientist, this one in California, said that her death might set back the search for a cure five years. "She was a key player," he said. "Smart, yes, but more—I once heard someone refer to her as 'a natural-born facilitator,' and that’s as good a description as any. Ann was the kind of person who holds other people together. Her death is a great loss to the dozens of people who knew and loved her, but it’s an even greater loss to this cause." Billy Unger was also easy enough to find. His picture topped page one of the Stovington Weekly Courant instead of getting stuck down there in The Dead Folks' Nook, but that might have been because there weren’t many famous people in Stovington. Unger had been General William "Roll Em" Unger, winner of the Silver Star and Bronze Star in Korea. During the Kennedy administration he was an Undersecretary of Defense (Acquisition Reform), and one of the really big war-hawks of that time. Kill the Russkies, drink their blood, keep America safe for the Macy’s Thanksgiving Day Parade, that sort of thing. Then, around the time Lyndon Johnson was escalating the war in Vietnam, Billy Unger had a change of mind and heart. He began writing letters to newspapers. He started his op-ed page career by saying that we were handling the war wrong. He progressed to the idea that we were wrong to be in Vietnam at all. Then, around 1975 or so, he got to the point of saying all wars were wrong. That was okay with most Vermon ters. He served seven terms in the state legislature, starting in 1978. When a group of Progressive Democrats asked him to run for the U.S. Senate in 1996, he said he wanted to "do some reading and consider his options." The implication was that he would be ready for a national career in politics by 2000, 2002 at the latest. He was getting old, but Vermonters like old guys, I guess. 1996 went past without Unger declaring himself a candidate for anything (possibly because his wife died of cancer), and before 2002 came around, he bought himself a big old dirt sandwich and ate every bite. EVERYTHING'S EVENTUAL There was a small but loyal contingent in Stovington which claimed Roll Em’s death was an accident, that Silver Star winners don’t jump off their roofs even if they have lost a wife to cancer in the last year or so, but the rest pointed out that the guy probably hadn’t been repairing the shingles—not in his nightshirt, not at two o’clock in the morning. Suicide was the verdict. Yeah. Right. Kiss my ass and go to Heaven. XVIII I left the library and thought I’d head home. Instead, I went back to the same park bench again. I sat there until the sun was low and the place had pretty much emptied out of kids and Frisbee-catching dogs. And although I’d been in Columbia City for three months by then, it was the latest I’d ever been out. That’s sad, I guess. I thought I was living a life here, finally getting away from Ma and living a life, but all I’ve been doing is throwing a shadow. If people, certain people, were checking up on me, they might wonder why the change in routine. So I got up, went on home, boiled up a bag of that shit-on-a-shingle stuff, and turned on my TV. I’ve got cable, the full package including premium movie channels, and I’ve never seen a single bill. How’s that for an eventual deal? I turned on Cinemax. Rutger Hauer was playing a blind karate-fighter. I sat down on the couch beneath my fake Rembrandt and watched the show. I didn’t see it, but I ate my chow and looked at it. I thought about stuff. About a newspaper columnist who had liberal ideas and a conservative readership. About an AIDS researcher who served an important linking function with other AIDS researchers. About an old general who changed his mind. I thought about the fact that I only knew these three by name because they didn’t have modems and e-mail capability. There was other stuff to think about, too. Like how you could hypnotize a talented guy, or drug him, or maybe even expose him to other talented guys in order to keep him from asking any of the wrong questions or doing any of the wrong things. Like how you could make sure such a talented guy couldn’t run away even if he happened to wake up to the truth. You’d do that by setting him up in what was, essentially, a cashless existence . . . a life where rule number one was no ratholing any extra dough, not even pocket-change. What sort of talented guy would fall for something like that? A naive one, with few friends and next to no self-image. A guy who would sell you his talented soul for a few groceries and seventy bucks a week, because he believes that’s about what it’s worth. I didn’t want to think about any of that. I tried to concentrate on Rutger Hauer, doing all that amusing blind karate shit (Pug would have laughed his ass off if he’d been there, believe me), so I wouldn’t have to think about any of that. Two hundred, for instance. There was a number I didn’t want to think about. 200. 10 x 20, 40 x 5. CC, to the old Romans. At least two hundred times I’d pushed the button that brought the message DINKYMAIL SENT up on my screen. It occurred to me—for the first time, as if I was finally waking up—that I was a murderer. A mass murderer. Yes indeed. That’s what it comes down to. Good of mankind? Bad of mankind? Indifferent of mankind? Who makes those judgements? Mr. Sharpton? His bosses? Their bosses? And does it matter? I decided it didn’t matter a fuck in a rabbit-hutch. I further decided I really couldn’t spend too much time moaning (even to myself) how I had been drugged, hypnotized, or exposed to some kind of mind-control. The truth was, I’d been doing what I was doing because I loved the feeling I got when I was composing the special letters, the feeling that there was a river of fire running through the center of my head. Mostly, I’d been doing it because I could. “That’s not true,” I said . . . but not real loud. I whispered it under my breath. They probably don’t have any bugs planted here, I’m sure they don’t, but it’s best to be safe. EVERYTHING'S EVENTUAL I started writing this . . . what is it? A report, maybe. I started writ- ing this report later that night . . . as soon as the Rutger Hauer movie was over, in fact. I write in a notebook, though, not on my computer, and I write in plain old English. No sankofites, no bews, no smims. There's a loose floor-tile under the Ping-Pong table down in the base- ment. That's where I keep my report. I just now looked back at how I started. I've got a good job now, I wrote, and no reason to feel glum. Idi- otic. But of course, any fool who can pucker is apt to whistle past the graveyard. When I went to bed that night, I dreamed I was in the parking lot of the Supr Savr. Pug was there, wearing his red duster and a hat on his head like the one Mickey Mouse wore in Fantasia—that's the movie where Mickey played the Sorcerer's Apprentice. Halfway across the parking lot, shopping carts were lined up in a row. Pug would raise his hand, then lower it. Each time he did this, a cart would start rolling by itself, gathering speed, rushing across the lot until it crashed into the brick side of the supermarket. They were piling up there, a glittering junkheap of metal and wheels. For once in his life, Pug wasn't smiling. I wanted to ask him what he was doing and what it meant, but of course I knew. "He's been good to me," I told Pug in this dream. It was Mr. Sharpt- ton I meant, of course. "He's been really, really eventual." Pug turned fully to me then, and I saw it wasn't Pug at all. It was Skipper, and his head had been smashed in all the way down to the eyebrows. Shattered hunks of skull stuck up in a circle, making him look like he was wearing a bone crown. "You're not looking through a bombsight," Skipper said, and grinned. "You are the bombsight. How do you like that, Dinkster?" I woke up in the dark of my room, sweating, with my hands over my mouth to hold in a scream, so I guess I didn't like it very much. XIX Writing this has been a sad education, let me tell you. It’s like hey, Dink, welcome to the real world. Mostly it’s the image of grinding up dollar bills in the kitchen pig that comes to me when I think about what has happened to me, but I know that’s only because it’s easier to think of grinding up money (or chucking it into the storm-drain) than it is to think about grinding up people. Sometimes I hate myself, sometimes I’m scared for my immortal soul (if I have one), and sometimes I’m just embarrassed. Trust me, Mr. Sharpton said, and I did. I mean, duh, how dumb can you get? I tell myself I’m just a kid, the same age as the kids who crewed those B-25s I sometimes think about, that kids are allowed to be dumb. But I wonder if that’s true when lives are at stake. And, of course, I’m still doing it. Yes. I thought at first that I wouldn’t be able to, no more than the kids in Mary Poppins could keep floating around the house when they lost their happy thoughts . . . but I could. And once I sat down in front of the computer screen and that river of fire started to flow, I was lost. You see (at least I think you do), this is what I was put on Planet Earth for. Can I be blamed for doing the thing that finishes me off, that completes me? Answer: yes. Absolutely. But I can’t stop. Sometimes I tell myself that I’ve gone on because if I do stop—maybe even for a day—they’ll know I’ve caught on, and the cleaners will make an unscheduled stop. Except what they’ll clean up this time will be me. But that’s not why. I do it because I’m just another addict, same as a guy smoking crack in an alley or some chick taking a spike in her arm. I do it because of the hateful fucking rush, I do it because when I’m working in Dinky’s Notebook, everything’s eventual. It’s like being caught in a candy trap. And it’s all the fault of that dork who came out of News Plus with his fucking Dink- EVERYTHING’S EVENTUAL *patch* open. If not for him, I’d still see nothing but cloud-hazy build- ings in the crosshairs. No people, just targets. You are the bombsight, Skipper said in my dream. You are the bomb- sight, Dinkster. That’s true. I know it is. Horrible but true. I’m just another tool, just the lens the real bombardier looks through. Just the button he pushes. What bombardier, you ask? Oh come on, get real. I thought of calling him, how’s that for crazy? Or maybe it’s not. “Call me anytime, Dink, even three in the morning.” That’s what the man said, and I’m pretty sure that’s what the man meant—about that, at least, Mr. Sharpton wasn’t lying. I thought of calling him and saying, “You want to know what hurts the most, Mr. Sharpton? That thing you said about how I could make the world a better place by getting rid of people like Skipper. The truth is, you’re the guys like Skipper.” Sure. And I’m the shopping cart they chase people with, laughing and barking and making race-car sounds. I work cheap, too . . . at bar- gain-basement rates. So far I’ve killed over two hundred people, and what did it cost TransCorp? A little house in a third-rate Ohio town, seventy bucks a week, and a Honda automobile. Plus cable TV. Don’t want to forget that. I stood there for awhile, looking at the telephone, then put it down again. Couldn’t say any of that. It would be the same as putting a Baggie over my head and then slitting my wrists. So what am I going to do? Oh God, what am I going to do? XX It’s been two weeks since I last took this notebook out from under the basement tile and wrote in it. Twice I’ve heard the mail-slot clack on Thursdays, during *As the World Turns*, and gone out into the hall to get my money. I’ve gone to four movies, all in the afternoon. Twice I’ve ground up money in the kitchen pig, and thrown my loose change down the storm-drain, hiding what I was doing behind the blue plastic recycling basket when I put it down on the curb. One day I went down to News Plus, thinking I’d get a copy of *Variations* or *Forum*, but there was a headline on the front of the *Dispatch* that once again took away any sexy feelings I might have had. POPE DIES OF HEART ATTACK ON PEACE MISSION, it said. Did I do it? Nah, the story said he died in Asia, and I’ve been sticking to the American Northwest these last few weeks. But I could have been the one. If I’d been nosing around in Pakistan last week, I very likely would have been the one. Two weeks of living in a nightmare. Then, this morning, there was something in the mail. Not a letter, I’ve only gotten three or four of those (all from Pug, and now he’s stopped writing, and I miss him so much), but a Kmart advertising circular. It flapped open just as I was putting it into the trash, and something fluttered out. A note, printed in block letters. **DO YOU WANT OUT?** it read. **IF YES, SEND MESSAGE “DON’T STAND SO CLOSE TO ME” IS BEST POLICE SONG.** My heart was beating hard and fast, the way it did on the day I came into my house and saw the Rembrandt print over the sofa where the velvet clowns had been. Below the message, someone had drawn a fouder. It was harmless just sitting there all by itself, but looking at it still made all the spit in my mouth dry up. It was a real message, the fouder proved it, but who had it come from? And how did the sender know about me? I went into the study, walking slowly with my head down, thinking. A message tucked into an advertising circular. Hand-printed and tucked into an advertising circular. That meant someone close. Someone in town. I turned on my computer and modem. I called the Columbia City Public Library, where you can surf cheap . . . and in relative anonymity. Anything I sent would go through TransCorp in Chicago, EVERYTHING'S EVENTUAL but that wasn’t going to matter. They weren’t going to suspect a thing. Not if I was careful. And, of course, if there was anybody there. There was. My computer connected with the library’s computer, and a menu flashed on my screen. For just a moment, something else flashed on my screen, as well. A smim. In the lower righthand corner. Just a flicker. I sent the message about the best Police song and added a little touch of my own down in The Dead Folks’ Nook: a sankofite. I could write more—things have started to happen, and I believe that soon they’ll be happening fast—but I don’t think it would be safe. Up to now, I’ve just talked about myself. If I went any further, I’d have to talk about other people. But there are two more things I want to say. First, that I’m sorry for what I’ve done—for what I did to Skipper, even. I’d take it back if I could. I didn’t know what I was doing. I know that’s a piss-poor excuse, but it’s the only one I have. Second, I’ve got it in mind to write one more special letter . . . the most special of all. I have Mr. Sharpton’s e-mail address. And I have something even better: a memory of how he stroked his lucky tie as we sat in his big expensive Mercedes. The loving way he ran his palm over those silk swords. So, you see, I know just enough about him. I know just what to add to his letter, how to make it eventual. I can close my eyes and see one word floating there in the darkness behind my lids—floating there like black fire, deadly as an arrow fired into the brain, and it’s the only word that matters: EXCALIBUR.
Traditional Irish Music in New Jersey and New York Peter L. Ford Lawrence E. McCullough Follow this and additional works at: http://scholarship.shu.edu/isds-studies Part of the American Studies Commons, and the Celtic Studies Commons Recommended Citation http://scholarship.shu.edu/isds-studies/5 Traditional Irish Music in New Jersey and New York In this pairing of articles, we are given two perspectives on traditional Irish music in New Jersey and New York. Peter L. Ford and Lawrence E. McCullough, both practitioners of this art form, occupy different yet complementary positions in the trad scene in our area. Ford is an up-and-coming musician, building a strong name for himself because of his noteworthy musical skill and bridging genres and learning the unique ways in which trad music enhances his own appreciation of the music of his heritage. McCullough is a sage, bearing a Ph.D. in ethnomusicology and participating for years in egalitarian sessions with seasoned musicians and neophytes alike. In this publication, Ford provides us with a creative, impassioned, and honest recounting of his own experiences in the trad music scene, and teaches us what he has learned about how to get involved in this always-evolving art form. McCullough counterbalances Ford’s exploration with a brief history of trad music and an outline of its increasing visibility in our area. We think that you’ll find both of these pieces instructive for seasoned musicians, new musicians, and those whose only instruments are fingers tapping the table and toes tapping the floor in the neighborhood pub. Getting Good: Trad-heads, Tunes, and Amateurs By Peter L. Ford The bar was packed. There was some sort of community fundraiser going on, cramming men and women in their late thirties up against the bar-top and into each other’s faces, but that did not stop anyone from yelling hoarsely into each other’s ears. Under a canopy of flat screen televisions and pennants from Glen Ridge’s athletic past, people moved through the crowd, a drink in either hand, like ants bearing a cold, liquid crumb. Directly opposite, in the front corner of the bar, I sat around a table with five other musicians. Larry McCullough, playing flute and whistle that night, turned to me between a set of tunes and said, “We should go around this place and drop an Ambien in about ten drinks. See if we can get some sort of osmosis effect going.” I doubted that Ambien could affect a group of revelers who likely have purses full of similar “prescriptions,” but their volume didn’t stop our playing. After the waitress came with another round of the drinks for the musicians, courtesy of the owner, a young fiddler named Amy looked around and launched into an up-tempo reel. The volume of the other patrons forced us to lean in to hear what the tune was. Like fans in a stadium, a wave went around the circle, each of us nodding in understanding once we figured it out, and we started playing our own particular instrument. I had never met several of the players that night, but all of us played continuously for three hours, save the odd cigarette, knowing the tunes but not each other. The red-faces at the bar were as oblivious to us as we were to them, but sitting near us were a few older couples tapping their feet along with the music, offering a clap or two between sets. That was all we could expect and that was enough, because we had the music, and the music we were playing we can only play with those who know it, so in a sense, we were all of us playing for ourselves. Beneath the personal and experiential aspect of the Irish traditional music, there is a cultural and historical component. Granted, there is a repository of thousands of tunes, most of them written in the eighteenth and nineteenth centuries, and in comparison, there have been few additions to the modern tune lexicon. I have to wonder then, how is this music so alive when the tunes have the vitality of Latin? It is like the relationship of the museum to the studio, or the English Department to the Creative Writing Department. Where is it preserved and where does it grow? The music is being preserved, but in the people I have talked to and played with, I tried to understand if trad is kept in formaldehyde. I do not think so as I sit in the corner of a bar sweating and strumming to songs older than the town I’m in. I have been playing Irish traditional music with some seriousness for about three and a half years. By playing, I mean I have spent hours at home trying to learn as many tunes as I can so that I can go to a bar and sit in with a group of musicians who play this music. That is putting it quite simply. Playing Irish music in a modern context is much different than being in a rock band or a jazz group. To play and perform “trad” is an odd amalgam of individual work and democratic consensus. The “performing” context usually takes place at a bar that designates one night a week or two in which musicians, mostly playing fiddles, whistles, flute, guitars, and accordions, among other instruments, are allotted a corner of the bar to sit together in a circle and play tunes. On my own journey within Irish traditional music, I slowly learned how to act in a session, and also learned a few more tunes. All the while, though, I wondered as I ventured through this new musical landscape, who are these people, and why are they playing this music? These are basic questions that can be asked of most any music, but there is something different about Irish music that befuddles these broad questions. The root of the matter is that this is an ethnic genre primarily played and kept alive by amateurs. It comes from one group of people, but I sit in at sessions next to a former member of the Israeli army, or across from a Japanese business man and think, I’m Irish, but I blow compared to these guys. At the same time, I think of many of the musicians I play with in other genres and see long hair and cigarettes, while at a session I sometimes feel grossly under-salaried hanging out with clean-cut lawyers. They play tunes, not songs, because songs often imply some element of rehearsal and dynamics. “Trad,” however, is unrehearsed, that is, no one is really sure who is going to show up at the session. It is an open session, meaning that anyone and everyone is welcome to play, and the lone qualifier is knowing some tunes. Larry McCullough, Ph.D. ethnomusicologist and musician, the Virgil to my Dante in the theoretical world of Irish Traditional music, told me, “it’s easy . . . well, let’s say the entry level is low-bar . . . you can go into a session, play one tune and you’re actually participating . . . try walking into a Peruvian music session or a Middle Eastern session and “jamming” with those cats . . . the level of even basic knowledge is way too high, but with old-time and Irish you can start out totally basic and work your way up and still play in a session or ceili with master players.” When I asked him what is so appealing about this music to people of different background and skills levels, he said that it is “because you don’t really need to know a special language to participate in ITM (unless you want to sing Gaelic songs), it’s an idiom open to anyone who can play basic tunes in a basic fashion, and with the community that develops at sessions, it’s attractive to amateurs as well as professionals.” I came to my first session knowing maybe four tunes, which by most standards is a drop of water in the ocean. I sat down in a circle of guys in their fifties and sixties. I brought with me my significant background in bluegrass, an American mutation of the music the Scots-Irish brought to the States in the nineteenth century. I thought my loose musical-genetic history would ease me into the group of old, red-faced men sitting around with familiar instruments. I was pathetically wrong. Not only was there a new vocabulary and repertoire, there was a new decorum and etiquette to the music, and all of this among strangers who knew these hidden codes. It is relatively easy to take an etiquette misstep at a session. There are no rule books or finishing schools for people who set out to play Irish music. Instead, these lessons are learned through looks of derision or through the eloquence of irate musicians outside the bar during a smoke. Here is a quick tutorial that I approach sessions with: 1) Know tunes – if you show up and you only know five or six, you are going to run out of tunes in about five minutes. For some beginners, this crisis can be averted by playing an instrument that is not reliant on actual melodies, i.e., chordal instruments (guitar or bouzuki), or percussion (bodhran, spoons). Granted, playing in the rhythm section of an Irish session has its own difficulties; that is, as opposed to having thousands of tunes written out for melody, rhythm and accompaniment are entirely improvisational, which can lead to its own assortment of embarrassing train-wrecks. 2) Always have a “set.” A set is a combination of tunes, usually three, that are strung together so as to create a longer piece. Most, if not all, of these tunes run about forty-five seconds long. Most sessions will play each tune three times, and then go onto the next tune, and so on. Therefore, there is a total playing time of about four to five minutes for each set. These sets often combine somewhat dissimilar tunes in terms of keys. An average set might start with a tune in G, then go to one in D, and then maybe back to G, which lends a mood change to the set. However, sets at a session almost never combine different types of tunes, i.e., jigs and reels, polkas and slip jigs. This is important because these “types” are in different time signatures. If a reel goes to a jig, the entire feel of the set has to be re-oriented, often losing the momentum of the previous tune or tunes. On the topic of sets, if you ever encounter a session and you hear someone start a tune, and then they only play that single tune, you can see faces of loss and despair if another tune does not immediately follow. Stopping after a minute and a half of playing feels like coitus interruptus set to music. I went outside with Steve Wickins for a smoke after one such incident. Just as I was lighting my cigarette Steve exclaimed, “ Somebody’s got to talk to that f----- . Who has the b---- to do that to some of the players in there? And then to look around like a grinning idiot afterwards?” He turned away, threw his hands up and said to the street, “Unbelievable!” These players take this stuff very seriously. 3) Relax. Though it sometimes feels like you are playing a touch football game with the Steelers, you have to remember that everybody started somewhere. My problem was often showing up late or stepping out to get a drink or a smoke and not realizing that a tune from my limited repertoire was being played. Later on in the session I would suggest playing it in a set. I remember one time doing as much and then looking across to a fiddler as he said, “Well, we already played it.” Larry McCullough, who was sitting next to me, put his whistle up to his mouth and said, “ But we can play it again,” and then ripped right into it. It was like having a dunce’s cap pulled off my head, but set nearby in case I should want to put it on again. I am left wondering why is this music, a decidedly ethnic genre that has a running index of about thirty-thousand tunes, played by such various people. And it’s not just an outlet for some – it is a very real and difficult hobby. I talked to one player, Steve Wickins, about a Japanese fiddler that makes most of the sessions, and Steve re-enacted the fiddler saying in a definitely un-P.C. imitation, “If I learn three tunes every day, I should be very good in ten years.” The math does not work out, but the intention is true: this is a serious music that takes time and effort. It is about loving, just loving the music and the process. Sitting down to write about this music and the people and who play it, I find myself searching for what makes people approach an ethnic music like trad with a professional diligence for amateur results. By this I mean, they take the time and energy to perform at exceptionally high levels of playing, but for no pay and little recognition. A significant number of these players are not playing because it was their parents’ music, or anything blood-related; rather, they came upon a style of music that is daunting yet feasible. Moreover, it does not entertain the illusions of selling out stadiums or waking up with groupies. Instead the reward is getting in some laughs between tunes, sipping a pint, and showing off what you know and learning what you didn’t. Larry McCullough handed me a copy of an article which he had published in 1980, and I’m pretty sure this was the first copy he made judging by the rust on the staples. In it he traces the development of the session, with its origins in the ceili (an Irish dance party) up to its modern formations. Before the twentieth century, Irish music was a performed by a soloist, but it was not until the growing popularity of ceilithe (ceili plural) that a “band” was required, thus forcing the musicians to tailor their individual abilities into a cohesive dance band. A testament to Larry’s intelligence and class is his ability to sidestep the St. Patrick’s Day ignominy without even mentioning it: “the Irish social organizations provide a Cinderella community that comes into being for a day or a night once a week, once a month, or perhaps only once a year before vanishing again upon conclusion of the particular event." Larry McCullough, at around 6’1”, stands out among many of the short, and sometimes stout, players at the session. It is difficult not to focus on him despite his usual position in a dark periphery of the players’ circle. Moreover, he’s the guy in the white linen suit. I’ve heard another flautist describe Larry and his style as “a very fine, smooth, beautiful, crushed velvet sock.” Larry brings a level of class to the congregation of musicians dressed in jeans, t-shirts, or whatever they still have on from work. Larry’s attention to his breezy appearance crosses over to his free, yet subtly thorough, playing. I first met Larry at Kilkenny House in Cranford, NJ, when he sat down next to me about forty-five minutes after the session started. After a brief nod to me, during which his brushed-back brown hair stayed eerily put, Larry leaned in to listen to what the tune was and immediately started playing along. I got up to catch a smoke with Steve after about two more sets, and as Steve cupped his around his lighter he spoke through the cigarette between his lips, “You know Larry McCullough’s sitting next to you.” In my ignorance I said something to the effect of, “Well, does he know he’s sitting next to me?” “Don’t be a t---,” Steve told me. If you are a real trad-head, you keep your ear to the ground, staying abreast of who is tapping their feet in the growing circle of traditional Irish music in the New York City area. --- Knowing not only the music, but also the players, is of unspoken importance, and Larry exists in a weird Venn-diagram in which he knows the tunes, knows the players, and everybody knows about him. Larry is not only an authority on the techniques of trad, but he is also a Ph.D. ethnomusicologist. With his hair falling onto his shoulders and a glass of water with lemon typically placed in front of him, I thought that I might consider Larry an academic if I went to college under a beach umbrella with a margarita, but more likely a pint of stout, sitting in front of me. As I’ve come to know Larry, I have learned that he has done a lot of stuff, really well. As a playwright and author he’s won 48 awards in 32 literary competitions, as well as publishing 182 poems and short stories in 92 North American literary publications. As a musician, he has played on over 49 major label recordings, as well as working on the soundtracks for several of Ken Burns’s documentaries, not to mention the Neil Jordan film, *Michael Collins*. He has published over 1,200 newspaper and magazine articles. His work with theatre has led him to compose scores for numerous plays and incidental theatre. Larry, true to form, was easy-going when he and I were sitting together at a session at Fitzgerald’s in Glen Ridge, NJ on a particularly loud night. Loud is an understatement. It was like trying to hum a tune in the middle of a stampede on the Serengeti. There was some sort of fundraiser going on, filling the bar with middle-aged parents getting lit while babysitters counted the minutes back home. I have no problem with a nice rowdy crowd getting lit, but being on the player side of the scene is exceptionally different – imagine tuning in the Thunderdome. Remember, one of the key aspects of a session is it is acoustic – no electric guitars to cut through three guys hollering about their handicap, and let’s suppose they’re talking about golf. Back at Fitzgerald’s, I couldn’t help but think about the people with whom I was playing. Next to me was Amy, a petite girl with a background specialty in Cape Breton fiddling; across was Greg, a tall, lumberjack-looking type with a resonator mandolin; next to him was Steve, his shaved head and glasses common to German architects hovering over his bodhran; next to me was Larry, pulling whistles out of his suit coat magically between tunes and sips of water; and then me, younger than everyone else and making up the chords as I went along. We were an odd bunch. It is terrible to judge by appearances, but I can tell that most everyone is approaching this music with some varied musical experience other than playing trad. Steve is a perfect example, if there can be one, of the unusual backgrounds that most players in the U.S. walk into a session with. Firstly, he undercuts this idea because he is British. Steve came over to the States with one of the many rock bands he played with in the mid-Eighties. He still plays in rock bands, though not professionally anymore. His current band, Streams of Whiskey, is a Pogues cover band. The Pogues are a band from Ireland and England that often takes traditional Irish songs and put them through a blender of punk rock and jazz. Steve’s voice has an eerie similarity to that of the band’s lead singer, Shane MacGowan – helped by decades of smoking. His raspy Sussex accent seems an anachronism in playing trad, but in truth, it is not. Most of the players at sessions are of limited, if any, Irish descent. Not to mention that there is a significant population of trad musicians (some of the best) in the United Kingdom. Steve also looks a bit different than everyone else. He seems younger than the other older guys that show up to play; there is something about his thick-rimmed glass and how he keeps his head shaved to the skin that gives of an impression of youth. Though he has two daughters in college, he brings a rock attitude to this seemingly old-fashioned music. He and I sync up during sets, playing behind the music with an intense syncopation that sometimes throws other players off because of our steadfast time. The beats he plays are as un-Irish as his accent, but he still knows when and where to lay into a driving traditional rhythm. Steve had always been a drummer and a singer, albeit in punk and rock groups, but in Irish sessions, he plays the bodhran. The bodhran (pronounced bow-rah-n) is essentially a drum that has not changed much since the Stone Age. It was traditionally a war instrument, like the pipes and fifes, but since the 1960s, it has developed into a very serious instrument, both in composition and technicality. It also is the source of more jokes than the banjo - if you can believe that. It is a large wooden rim with a calf-skin stretched across one side, and the musician places one hand inside of the open end and controls the pitch by stretching or loosening the skin. It is not unlike the sound of some African drums, but the main difference is that it is struck with a tipper. A tipper is a rod about six to eight inches long in various shapes made of different types of woods, depending on the sound the musician wants. Steve told me one joke that he particularly hates about bodhrans: “Q: What is the best type of tipper?” “A: A penknife.” As I smirked, Steve said with a sneer, “Clever.” Bodhran is perhaps the instrument that most people think that they can immediately play when setting out to play Irish music. Yet like the experiences of any instrument in trad, it is not as easy as it looks. Firstly, and most importantly, it requires a sense of time. Time is a peculiar thing in trad; that is, it is often quite fluid. Depending on who is playing, time is treated the same way it is in any music. It should be consistent, un-changing. Since Steve and I are often a two-man rhythm section for the sessions we go to, and we have a good deal of experience playing other styles of music, I would like to say we have pretty good time, which leads to some knowing looks across the circle between him and me when there is player leading a tune with the meter of a dying jack-in-the-box. Then again, Steve really appreciates certain players who show up to most of the sessions who play out of tune and out of time. What he respects in these people is first and foremost that they have heart. Not to mention they know a bunch of tunes. Though hearing some of these “heartfelt” players by themselves can recall chalkboards and cats, what they manage to do is keep the session moving. The modern session is never an individual effort. It almost seems rude to have all of these people drive countless miles to sit around as one person performs a small concerto. That is not to say that it does not happen. Sometimes a particular guest or a regular who has been away for a long time will be asked to do something by himself. It is still uncommon. The same idea applies when someone plays a tune that no one else knows. It is not that the other players do not appreciate it, but the sound is so thin without the rest of the group. It does not have the same energy that fills a pub when everyone is digging into an up-tempo tune. This seems to be the reason Steve got into the music. He loves the idea that you can just show up, do your best, and “you don’t have to lug any g--d--- gear around.” I feel the same way, and I am sure most other players do, too. It is like playing a pick-up football game: everyone knows the rules, each person knows their particular strengths, and they all know that after the game they will be better for the exercise and the camaraderie. In sessions, however, you can drink. Steve does not drink. For that matter, a good number of the players do not drink. Many have a cup of tea, coffee, or glass of water. This somewhat confuses the idea that most people have about Irish music. For many, it is some drinking songs on a juke box on March 17th, yet most of the singing that is infrequently done at sessions pertains to the I.R.A. of some other melancholy subject relating to having to leave Ireland. As a guitar player, I have decided to update my repertoire by learning some of these songs, but also with the intention that they have a specific melody that other instruments usually play. It is the same idea as playing a set alone, it just does not have the same collective frequency without the group playing together. That is not to say that I do not have a couple of drinking songs in my bag. These types of songs are what the “crowd,” and I use that word loosely, can get into. Singing and lyrics are something that anyone with a basic vocabulary can access. Moreover, it is a nice break for the musicians who are not playing anything. This is usually when Steve and I go out to catch a smoke before the next set begins. On a Wednesday night in December when it was really starting to get cold, Steve and I stood outside of The Kilkenny House in Cranford, NJ, talking about some of the players just on the other side of the windows. It was around 10:00 and the road was empty from where we were on a small side street of the downtown. This “imitation-Pub,” as Steve calls it, is a lot like most of the pubs in North Jersey. It has some memorabilia of Ireland hanging on the yellow, sponge-painted walls, demonstrating an obvious attempt at recreating the smoke-stained inside of a real Irish pub. Its laminated menus with a section called “Irish Specialties” are a far cry from the chalkboard menus of Ireland that have not been washed in decades. The big difference is the Clockwork Orange-esque ubiquity of flat screen televisions. “You would never see that over there [Ireland],” Steve said of the shiny screens all over the bar. “They might bring one in for the World Cup. And that is your country playing. None of this bullshit about minor league baseball,” He is bothered by the “fakeness” of these pubs. It is not uncommon to finish a set and hear the radio playing through the speakers near the ceiling. Invariably, someone gets up to tell the bar to turn them off, but it says something about sessions: we are not necessarily asked to play, but allowed to play. The painful thing is that we do not really bring in a crowd. That is not to say that as people are leaving they often come by the circle and say what a nice surprise it was to hear such great music. This weird drama often permeates the Kilkenny House. Sometimes the group will be so into a particular set that we all jump out of our seats when the guys at the bar holler after a touchdown. There are never stages at sessions, nor are there fancy lights, fog machines, or rooms in the back to warm up. There are still petulant owners, managers, and bartenders. At another session at the Kilkenny House, we were finishing up, and Rich Brautigan, a banjoist and singer, said that he would like to play the last set for a group representing some Irish organization (what my grandmother referred to as “gun-runners” for the I.R.A.) from a nearby town. Apparently one of these members said to the manager something to effect of “You c---- should treat the band a lot better.” Apparently he noticed that the radio was on. As we packed up, the manager, a large red-faced man from Kilkenny, Ireland, came over and yelled at Rich and told him to tell those people to never come back. I was surprised anyone was even listening, let alone observing the treatment of the musicians. I guess this is worth chalking up as a resounding round of applause. Regardless, these moments of appreciation are few. Playing at sessions never really feels like it is about the applause. Instead, it is one of the older players telling you it was a good set, or the feeling that you knew every tune for the past half hour. Oftentimes, when I get into my car, I think about how I had no idea what was going on at certain points, unable to find even the key of what was being played. Lately, these moments have been balanced out with the times where an older guy will compliment me on my chord choices. The best compliment I have received from Larry regarded either my health or my playing: “It feels empty when you step out for a smoke.” Steve and I still step out for smokes every hour or so. We, the de facto rhythm section, need a break because we play on every tune. Though we do not know the exact melodies of each set, we keep it moving, and we move it along best when all of the other players are in it too. Although most of the people who come to play at sessions are doing so out of their own pocket, they keep coming. They keep learning more tunes and meeting new people. I am not sure if there is any reason for playing this music beyond a simple love for it, an unfettered appreciation for the odd people, the sketchy bars, and the difficult music. It is a singular feeling: walking into a situation unsure of the outcome, let alone the process, but knowing you will be better for it, though I am not sure how. For the most part, it is just fun. Larry told me a story of an old tin whistler who was playing a ceili years ago. This guy danced a tune, then played a set, lowered his head as if he fell asleep, and died on the bandstand. Larry said with a smile, “I think I would like to go like that.” Reference The Irish Traditional Music Network in Northern New Jersey By Lawrence E. McCullough Irish traditional music is a vocal and instrumental idiom that coalesced in the early 1600s in Ireland, drawing structure, instruments and repertoire from Scots, English, French and native Irish musical sources. By the end of the 18th century, Irish traditional music was performed throughout Ireland in forms familiar to us today — dance music such as jigs, reels, hornpipe, slip jigs and song-based forms such as ballads, airs and the sean-nos style of Gaelic folk song. In the 19th century the music found its way to the English stage and American minstrelsy and vaudeville. In the second decade of the 21st century, the public performance of Irish traditional music in the Northern New Jersey/New York metro area is nurtured by a network of live music sessions, music clubs, programs on local radio and television stations and websites, blogs, online meet-ups and podcasts. The “session” is a musical occasion where the musician plays primarily for self-satisfaction in the company of fellow musicians. The musicians playing in a public session are not attempting to entertain, although there may be a number of bystanders who are thoroughly entertained by the performance. The chief motivation of a performer in a session is to express his or her musical individuality by engaging in a communal performance occasion with other musicians; if members of an audience are pleased with the musical performance, the musicians are also pleased, but their priority is toward making the musical performance fulfilling to themselves, not the audience. The session has been the chief vehicle for keeping Irish traditional music alive in the U.S. during years when the idiom was not so widespread or popular. The last two decades may have witnessed an increase in céilís, concerts and theatre shows featuring Irish traditional music, but, without the existence of the session, it is difficult to see how this revival could ever have been possible. Currently, there are 34 Irish traditional music sessions occurring at least monthly in the Northern New Jersey/New York metro area — 9 in New Jersey, 10 in Manhattan, 7 in the other New York City boroughs, 8 in Long Island and in Dutchess, Putnam, Rockland and Westchester Counties. Most public sessions are sponsored by and take place in commercial taverns. A few are convened by Irish traditional music clubs. These clubs are non-profit cultural organizations affiliated with CCE — Comhaltas Ceoltóirí Éireann (Musicians’ Association of Ireland) — a Dublin, Ireland-based musical organization formed in 1951 and sponsored by the Irish government. The Mid-Atlantic Region of CCE includes 10 music clubs, 7 of which are in the Northern New Jersey/New York metro area: Claddagh na nGael Branch (Central NJ), Michael Rafferty Branch (Northern New Jersey), Craobh Úll Mór Nua Eabhrac (New York City, NY), Killoran-Clancy Branch (Queens & Brooklyn, NY), Michael Coleman Branch (Bronx, Westchester, Rockland Counties, NY), Martin Mulvihill Branch (Rockland County, NY), Mulligan-Quinn Branch (Nassau & Suffolk Counties, NY). The CCE music clubs sponsor Irish traditional music concerts by local and visiting musicians, sessions, céilis, instruction in music and Irish language. The Mid-Atlantic Region clubs hold an annual music competition called a “fleadh cheoil,” at which music performers qualify to compete in the All-Ireland competitions for Irish Traditional Music held in Ireland each August. The music clubs have done much to increase the status of the performer of Irish traditional music by bringing about recognition of the performer as an active carrier of an important aspect of the Irish cultural heritage. Radio broadcasts in the Northern New Jersey/New York metro area that included Irish traditional music began in the 1930s. Today, the music can be heard on 16 programs aired on 11 New Jersey/New York AM and FM radio stations and two web-radio broadcasts. Irish Traditional Music performers are featured on the *Out of Ireland* syndicated television program produced at WLIW-TV, Channel 21, on Long Island since 1994. The show is carried by 31 U.S. public television stations with an estimated audience of 6.3 million Irish-American homes. Area performers of Irish traditional music use personal web sites to keep audiences and other performers aware of their performances and recordings. Irish traditional music news in the Northern New Jersey/New York metro area is circulated via online calendars such as the Ceol Agus Rince (“Music and Dance”) calendar compiled by Maureen Donachie, chair of the Craobh Úll Mór CCE music club. The calendar is located on the web at [www.my.calendars.net/ceolagusrince](http://www.my.calendars.net/ceolagusrince), and weekly updates are emailed to the subscribers. The Irish American Culture & Heritage Online Meet-up Group is based in Belmar, New Jersey and located on the web at [www.meetup.com/nj-irish-by-the-sea](http://www.meetup.com/nj-irish-by-the-sea). Founded in February, 2008, this online organization has over 100 members who gather to listen to Irish music, dancing, Gaelic sports, the Gaelic language and more. In 2011, fiddler Gwen Orel of Millburn, NJ, created a blog and podcast titled New York Irish Arts located on the web at [http://newyorkirisharts.blogspot.com](http://newyorkirisharts.blogspot.com). This includes articles, reviews and interviews on current Irish Traditional Music happenings in the Northern New Jersey/New York metro area. The years to come will undoubtedly see area performers and promoters of Irish traditional music make use of newly evolving mass-market communications technology. But the key to the music's future health will be the continued abundance of live music sessions and organized music club activity offering classes and events for musicians and their devotees.
Multimode quantum memory based on atomic frequency combs AFZELIUS, Mikael, et al. Abstract An efficient multimode quantum memory is a crucial resource for long-distance quantum communication based on quantum repeaters. We propose a quantum memory based on spectral shaping of an inhomogeneously broadened optical transition into an atomic frequency comb (AFC). The spectral width of the AFC allows efficient storage of multiple temporal modes without the need to increase the absorption depth of the storage material, in contrast to previously known quantum memories. Efficient readout is possible thanks to rephasing of the atomic dipoles due to the AFC structure. Long-time storage and on-demand readout is achieved by use of spin states in a lambda-type configuration. We show that an AFC quantum memory realized in solids doped with rare-earth-metal ions could store hundreds of modes or more with close to unit efficiency, for material parameters achievable today. Reference DOI: 10.1103/PhysRevA.79.052329 Multimode quantum memory based on atomic frequency combs Mikael Afzelius,* Christoph Simon, Hugues de Riedmatten, and Nicolas Gisin Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland (Received 9 June 2008; published 21 May 2009) An efficient multimode quantum memory is a crucial resource for long-distance quantum communication based on quantum repeaters. We propose a quantum memory based on spectral shaping of an inhomogeneously broadened optical transition into an atomic frequency comb (AFC). The spectral width of the AFC allows efficient storage of multiple temporal modes without the need to increase the absorption depth of the storage material, in contrast to previously known quantum memories. Efficient readout is possible thanks to rephasing of the atomic dipoles due to the AFC structure. Long-time storage and on-demand readout is achieved by use of spin states in a lambda-type configuration. We show that an AFC quantum memory realized in solids doped with rare-earth-metal ions could store hundreds of modes or more with close to unit efficiency, for material parameters achievable today. DOI: 10.1103/PhysRevA.79.052329 PACS number(s): 03.67.Hk, 42.50.Gy, 42.50.Md I. INTRODUCTION The distribution of entanglement between remote locations is critical for future long-distance quantum networks and extended tests of quantum nonlocality. It is likely to rely on quantum repeaters [1,2], which require quantum memories (QMs) that can store entanglement between distant network nodes [3,4]. Recent experimental achievements in quantum state storage [5–8] demonstrate that currently investigated QMs can store a single mode. Yet, long-distance quantum repeaters having QMs that are only capable of storing one mode would only generate very limited entanglement generation rates [9]. To achieve useful rates some way of multiplexing the QM will be required [10,11]. By using time [11], spatial [10,12,13], or frequency multiplexing to store single photons in many modes N, the entanglement generation rate can be increased by a corresponding factor N [11]. Here we consider multimode QMs capable of storing N temporally distinguishable modes, which is a natural form of sending information also used in today’s telecommunications networks. Time multiplexing is extremely challenging when using current QM protocols such as stopped light based on electromagnetically induced transparency (EIT) [14], photon echoes based on controlled reversible inhomogeneous broadening (CRIB) [15,16], or off-resonant Raman interactions [17]. For a single mode, N=1, the efficiency as a function of optical absorption depth d is similar for EIT, CRIB, and Raman-type memories [18,19]. For multimode storage using EIT and Raman, however, N scales as √d [20,21], which severely limits the number of potential modes in a practical experiment, while CRIB offers a better scaling since N∼d [11,21]. Still, even using CRIB, efficient multimode storage requires extreme absorption depths that are currently out of reach. In this paper we present a QM, where the number of potential modes is essentially independent of the optical depth. As we will show, efficient storage of hundreds of modes or more is then feasible with realistic material parameters. The QM is based on absorption of light by an ensemble of atoms on an optical transition which is inhomogeneously broadened. Ensembles are in general very attractive as QMs due to strong collective enhancement of the light-matter coupling [2]. Storage of single photons using EIT (stopped light) has been demonstrated with cold alkali atoms [6,8] which can be treated as homogeneous ensembles of identical atoms. Here we will instead consider ensembles of rare-earth-metal (RE) ions in solids, which are inhomogeneously broadened. Stopped light with storage times up to 1 s has been demonstrated in RE-doped solids [22,23], where an approximate homogeneous ensemble was created by spectrally isolating a narrow absorption peak through optical pumping. In contrast to this approach, the quantum memory proposed here uses the inhomogeneous broadening as a resource in order to achieve better multimode performance. For that one needs to coherently control the dephasing which is caused by the inhomogeneous frequency distribution of the atoms. The key feature of our proposal is to achieve this control by a specific shaping of this distribution into an atomic frequency comb. The paper is organized in the following way. In Sec. II we give an overview of the proposal using a simplified physical picture. In Sec. III we show results from an analytical analysis of the physics of atomic frequency combs, which is further detailed in Appendix. In Sec. IV the multimode storage capacity is discussed, and in Sec. V we discuss implementation of the quantum memory in rare-earth-ion-doped solids. Conclusions are given in Sec. VI. II. ATOMIC FREQUENCY COMBS The storage material is an ensemble of atoms with an excited state |e⟩ optically connected to two lower states |g⟩ and |s⟩, see Fig. 1. The states |g⟩ and |s⟩ are typically ground-state hyperfine or Zeeman states. We assume that the optical transition |g⟩−|e⟩ has a narrow homogeneous linewidth γh and a large inhomogeneous broadening Γm/(Γm/γh ≫ 1). This is the case for RE-doped solids that we will consider for physical implementation in Sec. V. The |g⟩−|e⟩ transition is spectrally shaped such that the atomic density function consists of a series of narrow peaks spanning a large frequency range, which we call an atomic frequency comb (AFC). This FIG. 1. (Color online) The principles of the proposed AFC quantum memory. (a) An inhomogeneously broadened optical transition |g⟩-|e⟩ is shaped into an AFC by frequency-selective optical pumping to the |aux⟩ level. The peaks in the AFC have width (FWHM) γ and are separated by Δ, where we define the FWHM as \( F=Δ/γ \). (b) The input field is completely absorbed and coherently excites the AFC modes, which will dephase and then rephase after a time 2\( π/Δ \), resulting in a photon-echo type coherent emission. A pair of control fields on |e⟩-|s⟩ allows for long-time storage as a collective spin wave in |s⟩, and on-demand readout after a storage time \( T_s \). can be done by frequency-selectively transferring atoms from |g⟩ to a metastable state |aux⟩, for instance a third hyperfine state, through optical pumping techniques (see Sec. V). Note that the maximum spectral width of the AFC is limited by the level spacings between the ground-state levels. We then consider a single-photon input field, having a spectral distribution \( γ_0 \) larger than the AFC peak separation \( Δ \), but narrower than the total width of the AFC \( Γ \), which is in resonance with the |g⟩-|e⟩ transition. If the atomic density integrated over the photon bandwidth is high enough, the photon can be totally absorbed by the AFC although the inhomogeneous broadening, spin-echo techniques can be used to exploit the homogeneous coherence lifetime of the system (see Sec. V). After absorption (at \( t=0 \)) the photon is stored as a single excitation delocalized over all the atoms in the ensemble that are in resonance with the photon. The state is described by a collective Dicke state [24] \[ |ψ⟩ = \sum_{j=1}^{N} c_j e^{iδ_j/2} e^{-i2k} |g_1 \cdots e_j \cdots g_N⟩, \tag{1} \] where \( z_j \) is the position of atom \( j \), \( k \) is the wave number of the light field (for simplicity, we only consider a single spatial mode defined by the direction of propagation of the input field), \( δ_j \) the detuning of the atom with respect to the laser frequency, and the amplitudes \( c_j \) depend on the frequency and on the spatial position of the particular atom \( j \). The collective state can be understood as a coherent excitation of a large number of AFC modes by a single photon. These modes are initially (at \( t=0 \)) in phase with respect to the spatial mode \( k \). But the collective state will rapidly dephase into a noncollective state that does not lead to a strong collective emission since each term acquires a phase \( \exp(iδ_j t) \) depending on the detuning \( δ_j \) of each excited atom. If we consider an AFC having very sharp peaks, then the detunings \( δ_j \) are approximately a discrete set such that \( δ_j = m_j Δ \), where \( m_j \) are integers. It follows that the collective state is re-established after a time \( 2π/Δ \), which leads to a coherent photon-echo [25–27] type re-emission in the forward direction. The efficiency of this process (see Sec. III for details) can reach 54% in the forward direction (limited only by reabsorption). But if the re-emission is forced to propagate in the backward direction, by a proper phase matching operation (see below), the process can reach 100% efficiency. The process described so far only implements a QM with a fixed storage time. In order to allow for on-demand readout of the stored field (which is a necessary requirement for use in quantum repeaters) and long-term storage, the single collective excitation in |e⟩ is transferred to a ground-state spin level |s⟩. This can be done by applying an optical control field on |e⟩-|s⟩, for instance a short \( π \) pulse. The excitation is thereafter stored as a collective spin wave, which is also the basis of storage in EIT, CRIB, and off-resonant Raman-type memories based on ensembles of lambda atoms [14,15,17]. The spin wave allows for long-lived storage since spin coherence lifetimes are generally longer than the optical coherence lifetimes. Moreover, the spin transition does not have a comb structure [28], which means that the evolution of the phases in Eq. (1) will be locked during the storage in the spin wave. If we assume that the spin transition is completely homogeneous, the storage time is only limited by the coherence lifetime of the spin wave. If there is inhomogeneous broadening, spin-echo techniques can be used to exploit the homogeneous coherence lifetime of the system (see Sec. V). To retrieve the field a second counterpropagating control field is applied after some time \( T_s \). These operations will result in a backward propagating output mode after a total time \( T_s + 2π/Δ \). As we will show below, the efficiency of the storage for backward retrieval can theoretically approach unity for high optical depths. III. ANALYTICAL TREATMENT We will now discuss some important features of the AFC and give quantitative formulas relating the input field to the output field as a function of the AFC parameters. This can be used to calculate, for instance, storage efficiency. To this end we have used an approximate linearized Maxwell-Bloch (MB) model. A linearized model can be used since the population in the excited state is negligible. For a single-photon input field at most one atom in the ensemble is excited. For multimode storage, the number of totally excited atoms should be much less than the total number of atoms, which is the case for the number modes we consider and the RE solids we discuss in Sec. V. The linearity of the analytical model also implies the equivalence between classical and single-photon dynamics [17,18,29]. The important features of the model are discussed below while the details of the calculations are given in Appendix. The matter part was assumed to be an ensemble of two-level atoms, including levels $|g\rangle$ and $|e\rangle$ in Fig. 1, and the light field was treated as a one-dimensional spatial mode. This model can fully describe the mapping of light onto the light field was treated as a one-dimensional spatial mode. The model did not include population relaxation ($T_1$) or decoherence ($T_2$). This is a valid approximation since the peaks in the AFC are assumed to be inhomogeneously broadened. Then all relevant dephasing times are much faster than $T_1$ and $T_2$ (as in the example given in Sec. V). In practice, however, the width of the individual peaks will be limited by the homogeneous linewidth $\gamma_\text{H} = 1/(\pi T_2)$. The two counterpropagating control fields were modeled by transferring the forward atomic mode, associated with the forward propagating optical mode, to a backward atomic mode [29]. This achieves the phase matching operation that results in a backward propagating optical mode. Clearly this approach assumes that the transfer efficiency of the control pulses is unity and that the spin transition is decoherence-free. We thus only analytically treat the physics of the atomic frequency comb, which is the unique feature of this protocol as compared to previous quantum memory proposals [14,15,17]. The transfer efficiency and spin decoherence could, however, be straightforwardly included with appropriate loss factors. The equations of motion describing the light-matter dynamics is given in Appendix [see Eqs. (A11)–(A4)]. In addition to the analytical calculations, we also show results from numerical solutions of the MB model. The atomic spectral distribution $n(\tilde{\delta})$ is a frequency comb described by a series of Gaussian functions characterized by the peak separation $\Delta$ and peak width $\tilde{\gamma}$, with an overall comb width of $\Gamma$ $$n(\tilde{\delta}) \propto e^{-\tilde{\delta}^2/(2\tilde{\gamma}^2)} \sum_{j=-\infty}^{\infty} e^{-(\delta - j\Delta)^2/(2\tilde{\gamma}^2)}.$$ The full width at half-maximum (FWHM) peak width is then $\gamma = \sqrt{8 \ln 2} \tilde{\gamma}$, and we define the finesse $F$ of the comb as $F = \Delta/\gamma$. We are interested in the regime where we have a significant number of well-separated peaks within the overall characteristic width of the AFC. Moreover, we assume that the spectrum of the photon is narrower than the width of the AFC but wider than the peak separation, i.e., $\Gamma \gg \gamma_p \gg \Delta \gg \tilde{\gamma}$. In order to have an efficient memory, the probability of absorption of the input mode must be sufficiently high. But to create a high finesse AFC atoms are removed, by optical pumping, from the natural inhomogeneous spectrum. This preparation step lowers the total density of atoms and hence the probability of absorption. The analytical calculations show that the amplitude of the forward propagating mode $E_{f}(z,t)$ after the sample of length $L$ is given by $$E_f(L,t) = E_f(0,t) e^{-\tilde{\alpha} L} = E_f(0,t) e^{-d/2},$$ where the effective absorption depth $d = \tilde{\alpha} L$ can be expressed as $$d = \frac{d}{F} \sqrt{\frac{\pi}{4 \ln 2}} = \frac{d}{F}.$$ The comb absorption is thus reduced by a factor of $1/F$, which is to be expected since the total density of atoms in the comb (integrated over the frequency bandwidth of the photon) is reduced by a factor of $1/F$ in the preparation step. But if the peak absorption depth $d$ of the comb is high enough, the total density of atoms in the comb can still be sufficiently high to absorb the input mode with close to 100% probability. An interesting feature of the AFC is that it can absorb uniformly over the frequency spectrum of the input mode although the atomic frequency comb has large “holes.” This can be understood by considering that the absorption is an event well localized in time, of the order $\tau = 1/\gamma_p$. In that case the light atom system reacts with a Fourier-limited resolution $\gamma_p$, which effectively smears out the structure of the AFC to an essentially flat distribution [see discussion preceding Eq. (A11)]. In other words the peak separation $\Delta$ must be smaller than the photon bandwidth $\gamma_p$. This also implies that Eq. (3) is only valid for times $t \ll 2\pi/\Delta$, i.e., before the appearance of the first emission due to rephasing of modes in the comb. By applying the two counterpropagating control fields, the spatial phase pattern of the atomic polarization changes such that it couples with the backward propagating field mode [15,16,29]. Under the assumption of unit transfer efficiency and no phase decoherence during the transfer to or storage in $|s\rangle$, the atomic phases will evolve to a collective state coupled to the backward propagating mode. This leads to emission in the backward mode. In Appendix [see Eq. (A18)] we show that the output field amplitude is a coherent sum over the amplitudes corresponding to all possible paths of the photon in the medium, where each path is characterized by a particular turning point in the medium. Even though there is absorption also along the path of the backward mode, a constructive interference effect between all these possible paths leads to the output amplitude potentially being arbitrarily close in magnitude to the input amplitude for large enough $d$. This interference effect is also present in the CRIB quantum memory scheme for backward retrieval [29]. The analytical calculation leads to the following relation between the forward input field $E_{\text{in}} = E_f(z=0,t=0)$ and output backward field $E_{\text{out}} = E_f(z=0,t=2\pi/\Delta)$ [see Eq. (A18)], $$E_{\text{out}} = -E_{\text{in}} e^{-i(2\pi \Delta)/(4L)} (1 - e^{-d/F})(e^{i(d/2)})(e^{d/4 \ln 2}).$$ The first factor represents a global phase shift that depends on the relative detuning $\Delta_0$ between the carrier frequency of the light and the center of the AFC. The second factor de- The efficiency can be close to 100% for large enough material by optimizing the storage efficiency can then be maximized for the given function of optical depth for different comb fineses in Fig. The dephasing during the storage in the optically excited state due to the finite width of the peaks. The dephasing factor can be understood by considering the dephasing during the storage in the optically excited state $|\psi\rangle$. In the qualitative description in Sec. II we assumed that each peak was a delta function, which leads to complete rephasing of collective state Eq. (1). Clearly finite Gaussian peaks will not lead to complete rephasing, which lowers the probability of re-emission. The decay of the re-emitted field amplitude is given by the Fourier transform of a peak in the comb [see Eq. (A6) and discussion preceding Eq. (A16)], in analogy with the role of the initial peak shape in the CRIB quantum memory protocol [29,30]. In the case of Gaussian peaks, the decay is given by $e^{-\frac{d^2}{2}}$, where $t=2\pi/\Delta$ is the storage time in the excited state. This factor can be expressed in terms of the finesse $F$, which leads to the last term in Eq. (5). To reduce this dephasing one should thus maximize the comb finesse $F$. The efficiency, defined as $\eta=|E_{\text{out}}|^2/|E_{\text{in}}|^2$, is plotted as a function of optical depth for different comb fineses in Fig. 2. For a moderate finesse of $F=4$, an efficiency greater than 50% can be achieved for $d=10$. For a high finesse, $F>10$, the efficiency can be close to 100% for large enough $d$. From an experimental point of view $d$ is often a fixed parameter. The storage efficiency can then be maximized for the given material by optimizing $F$ using Eq. (5) (see Fig. 3). This optimum in the choice of $F$ is due to a tradeoff between absorption probability (favoring small $F$) and low dephasing during storage (favoring large $F$). We will also briefly discuss the possibility of re-emission in the forward direction. This will occur if no control fields are applied or if the control fields are applied copropagating. As is shown in Appendix [see Eq. (A19)], this re-emission is limited in efficiency to 54% for an optimal optical depth of $d=2$. The optimum represents a tradeoff between strong light-matter coupling (favoring high optical depth) and reab- sorption of the re-emitted light as it propagates through the sample (favoring low optical depth). IV. MULTIMODE STORAGE CAPACITY The excellent multimode properties of the AFC based QM can be understood qualitatively as follows. We imagine that the input is a series of temporally distinguishable modes containing, with a certain probability, a single photon in each mode. The storage efficiency is uniform over all the modes since each mode spends the same time in the memory. Note that the effect of spin decoherence is also the same on each mode. If the control fields are applied as late as possible, the total duration of the input can be close to $T=2\pi/\Delta$, the time it takes to rephase the first mode that was absorbed. The shortest duration $\tau$ of one mode, however, is only limited by the total frequency bandwidth $\tau\sim 1/(N\Delta)$, where $N_{\mu}$ is the number of peaks in the comb. The number of modes $N=\pi T/\tau \sim N_{\mu}$ is then proportional to $N_{\mu}$, such that adding more peaks in the AFC allows one to store more modes. Thus, in materials with inherently large inhomogeneous broadenings (see Sec. V), one can increase the multimode capacity by making use of a wider range of the inhomogeneous broadening without having to increase the peak absorption depth by, for instance, increasing the atomic density in the sample. We can make a more detailed calculation of the multi- mode capacity by assuming that the input modes have Gaussian temporal shapes, where each mode occupies a tem- poral slot of duration $\tau$. It is important that the modes do not overlap too much, which in the end would produce errors. The amount of overlap that can be accepted depends on the particular application. In Ref. [11] an analysis of the error due to overlap was carried out in the context of a quantum repeater protocol in which the AFC QM could be used. There was shown that $\tau$ should be chosen as $\tau=12\pi/\Gamma$, where $\Gamma$ is the total memory bandwidth (note that here $\Gamma$ is expressed in radians), where the width $\Gamma$ is taken to be that of a square FIG. 2. (Color online) The storage efficiency is shown as a function of peak absorption depth $d$ for AFC finesse values of $F=4$, 6, and 10. The solid lines represent the efficiency calculated using the analytical result, Eq. (5), whereas the symbols represent the numerical calculation. As an example, for $d=40$ and $F=10$, an efficiency of 90% can be achieved. Even for an absorption depth of 25 and a modest finesse of 6, the efficiency reaches 80%. FIG. 3. (Color online) Efficiency as a function of comb finesse $F$ for peak absorption depths $d=5$ (black solid line), $d=10$ (red dashed line), $d=20$ (green dotted line), and $d=40$ (blue dashed-dotted line). The curves were calculated using Eq. (5). distribution, as in Ref. [11]. This also guarantees that the spectral content of the input modes can be fitted inside the AFC, which in turn results in negligible temporal distortion of the output modes. The width \( \Gamma \) can be related to the number of AFC peaks \( N_p = \Gamma / \Delta \). The total duration \( T \) of the input is \( T = 2\pi / \Delta - T_0 \), where \( T_0 \) is the time necessary for applying the two control fields. In the limit where \( T_0 \ll 2\pi / \Delta \), we have \( T \approx 2\pi / \Delta \). The number of total temporal modes then amounts to \( N = N_p / \pi \). The number of peaks that can be created will depend strongly on the inhomogeneous \( \Gamma_{in} \) and homogeneous \( \gamma_h \) linewidths of the material. The width of each peak cannot be narrower than the homogeneous linewidth, i.e., \( \gamma > \gamma_h \). Since an efficient memory (>90%) requires a finesse \( F > 10 \), it follows that \( \Delta > 10 \gamma_h \). The number of peaks will depend on the ratio of the maximum AFC bandwidth \( \Gamma \) to the peak separation \( \Delta \). The bandwidth will ultimately be limited by the inhomogeneous broadening of the material. In most materials, however, it will instead be limited by hyperfine or Zeeman transition spacings in order to avoid exciting multiple transitions that would induce quantum beat effects. In Sec. V we will give a detailed example where the number of peaks is of the order of hundreds with known material parameters. The AFC QM dramatically reduces the necessary absorption depth for multimode storage as compared to CRIB or EIT QMs since the multimode capacity is independent of the peak absorption depth of the material. For CRIB, \( d = 30N \) is required for storing \( N \) modes with an average efficiency of 90% [11], so for instance \( N = 100 \) requires \( d = 3000 \). In the case of EIT even larger \( d \) would be necessary due to worse scaling as mentioned in Sec. I. The AFC only requires \( d = 40 \) to reach the same efficiency, independently of \( N \). This makes efficient multimode QMs more realistic with current material properties, as we will discuss in the next section. V. IMPLEMENTATION USING RARE-EARTH-ION-DOPED SOLIDS As storage material we here consider RE-doped crystals, which have inherently large inhomogeneous broadening (0.1–10 GHz) and very narrow homogeneous linewidths (0.1–100 kHz) at low temperatures (typically less than 4 K) [31]. Note that the typical homogeneous linewidths correspond to optical coherence times ranging from \( \mu s \) to ms. Still RE ensembles have relatively high absorption coefficients at normal doping concentrations (10–100 ppm), typically in the range of 1–40 cm\(^{-1}\). RE crystals are therefore good candidates for the high-resolution spectral shaping we are discussing here. Reference [31] contains an extensive review of optical properties of different RE-doped crystals and glasses. The creation of the periodic narrow structure is the crucial enabling step for the AFC QM. Narrow absorbing peaks (<50 kHz) have been isolated within the inhomogeneous broadening by optical pumping (or spectral hole burning) [32–35]. In all stopped-light [22,23] and CRIB experiments [30,34] in RE solids to this date, a narrow absorption peak within a larger transmission hole has been created in order to have an approximate homogeneous distribution of atoms. Briefly, a large transmission hole is first created by spectral hole burning on the optical transition while sweeping the laser frequency. The pumped atoms are stored in another hyperfine level with long population lifetime. A narrow ensemble of atoms is then created in the hole by repumping atoms from the storage state to the initial state using a highly coherent laser source [36]. By repumping at different frequencies this method can be extended in order to create a series of peaks. One can also use other techniques in order to achieve frequency-selective optical pumping. For instance, one can use pairs of coherent pulses where each pair coherently transfers atoms to the excited state via a Ramsey interference [37]. Numerical simulations show that, by accumulating many pairs, narrow periodic structures can be created. This time-domain approach is interesting because in principle a time sequence can be created which has the appropriate frequency spectrum for creating an AFC with a certain finesse. Moreover a time-domain approach can be used for creating more complicated structures in frequency space, for instance multiple AFCs having different periodicity. The spin coherence times have the potential of being significantly longer than the optical ones since it is free of decoherence due to spontaneous emission. In Pr\(^{3+}\)-doped Y\(_2\)SiO\(_5\) crystals, one of the most studied RE-doped material, the spin coherence time is 500 \( \mu s \) at zero magnetic field [38], which can be extended to 82 ms by applying an orientation-specific magnetic field [39]. Fraval et al. [40] has also shown that it is possible to use dynamic decoupling methods developed in NMR spectroscopy to further extend the coherence time to 30 s. Yet another example is Eu\(^{3+}\):Y\(_2\)SiO\(_5\) where 15 ms spin coherence time was measured at zero field [41], and Tm\(^{3+}\):yttrium aluminum garnet (YAG) where 300 \( \mu s \) was obtained in a magnetic field [42]. Efficient transfer of population between the optically excited state and ground hyperfine states has been demonstrated in Pr\(^{3+}\):Y\(_2\)SiO\(_5\), and manipulation of coherence between the optically excited state and the two spin ground states has recently been demonstrated in a state tomography experiment of an ensemble-based spin qubit in Pr\(^{3+}\):Y\(_2\)SiO\(_5\) [43]. This shows the potential of spin states for long-term storage states for quantum information. We finally give a more detailed example based on europium-doped Y\(_2\)SiO\(_5\) crystals to show the potential for efficient multimode storage using an AFC based memory. Europium ions absorb at 580 nm, and have an appropriate energy structure with three ground-state levels and an optically excited state [44], as well as excellent optical [45] and hyperfine [41] coherence times. Given the very narrow homogeneous linewidth in this material (122 Hz [45]), one could realistically create an AFC with \( \gamma = 2 \) kHz and \( \Delta = 20 \) kHz (i.e., \( F = 10 \)). The total AFC bandwidth we take is 12 MHz, limited by hyperfine transition spacings, which results in \( N_p = 600 \) peaks. The maximum number of modes is then roughly \( N = N_p / 6 \approx 100 \). The absorption coefficient is about 3–4 cm\(^{-1}\) [45] so that \( d = 40 \) is within technical reach today using a multipass arrangement. Hence, one could then store 100 temporal modes in one single QM with an efficiency of 90%, which we verified by numerically simulating storage of 100 modes using the parameters above. We note that the efficiency stated above relates to the physics of the atomic frequency comb (see the model assumptions in Sec. III). A complete storage experiment including transfer to the spin state will be affected by the limitation in spin coherence time, for Eu³⁺:Y₂SiO₅ \( T_{29}^m = 36 \text{ ms} \) [41] has been observed so far, and by the transfer efficiency of the control fields (cf. discussion above). We conclude this section by observing that less studied RE-doped crystals could potentially store more modes due to larger hyperfine state separations, for instance erbium-doped crystals absorbing at 880 nm. VI. CONCLUSIONS We have presented a protocol for a quantum memory that can store efficiently a large number of temporal modes in a single atomic ensemble by creating an atomic frequency comb. In materials with large optical inhomogeneous and narrow homogeneous broadenings, this allows for high multimode capacity at moderate optical absorption depths. We argue that RE-doped materials have the necessary properties for implementing the proposed protocol. The inherent multimode property of the atomic frequency comb quantum memory promises to speed up the entanglement generation rates in long-distance quantum networks by several orders of magnitude. Recently, we have experimentally demonstrated a light-matter interface at the single-photon level [46] using an atomic frequency comb. This constitutes a proof-of-principle experiment of the idea presented in this paper. ACKNOWLEDGMENTS The authors acknowledge useful discussions with Imam Usmani, Nicolas Sangouard, Thierry Chancelière, Jean-Louis Le Gouët, and Stefan Kröll. This work was supported by the Swiss NCCR Quantum Photonics and by the European Commission under the Integrated Project Qubit Applications (QAP). APPENDIX: ANALYTICAL CALCULATIONS 1. Equations of motion In this Appendix we present the analytical calculations leading to the quantitative formulas in the paper. The basic equations describing the dynamics of the light-atom system are the same as in Sec. II of Ref. [29]. Both the field and the atomic polarization are described by (slowly varying) forward and backward modes, denoted as \( E_j(z,t) \) and \( \sigma_j(z,t) \) for the field, and \( \sigma_j(z,t;\delta) \) and \( \sigma_{j}(z,t;\tilde{\delta}) \) for the atomic polarization corresponding to atoms with resonance frequency \( \delta \). They satisfy the following equations, cf. Eqs. (5a) and (5b), and Eqs. (6a) and (6b) of Ref. [29], \[ \left( \frac{\partial}{\partial t} - c \frac{\partial}{\partial z} \right) E_j(z,t) = i\tilde{\varphi} \int_{-\infty}^{\infty} d\tilde{\varphi} n(\delta) \sigma_j(z,t;\tilde{\delta}), \tag{A2} \] \[ \frac{\partial}{\partial t} \sigma_j(z,t;\delta) = -i\delta \sigma_j(z,t;\tilde{\delta}) + i\varphi E_j(z,t), \tag{A3} \] \[ \left( \frac{\partial}{\partial t} - c \frac{\partial}{\partial z} \right) E_j(z,t) = i\tilde{\varphi} \int_{-\infty}^{\infty} d\tilde{\varphi} n(\delta) \sigma j(z,t;\tilde{\delta}). \tag{A4} \] Here \( \varphi \) is the dipole moment of the atomic transition, and \( \tilde{\varphi} = \frac{g_0}{\gamma_0} \), with \( g_0 = \sqrt{\gamma_0/(2\epsilon_0 V)} \), \( \omega_0 \) is the optical frequency, and \( V \) is the quantization volume; \( n(\delta) \) is the atomic spectral distribution, with \( \int_{-\infty}^{\infty} d\tilde{\varphi} n(\delta) = N_\alpha \), where \( N_\alpha \) is the total number of atoms. See Ref. [29] for more details. Note that \( n(\delta) = N_\alpha g(\delta) \) and \( \beta = \gamma/\gamma_0 \) in the notation of Ref. [29]. 2. Atomic spectral distribution and its Fourier transform Let us suppose that \[ n(\delta) \propto e^{-\delta^2/(2\gamma^2)} \sum_{m=-\infty}^{\infty} e^{-(\delta - \Delta n)^2/(2\gamma^2)}, \tag{A5} \] i.e., the atomic spectral distribution is a frequency comb with overall width \( \Gamma \), peak separation \( \Delta \), and individual peak width \( \gamma \). Note that in the paper we talk about the FWHM peak width \( \gamma = \sqrt{8 \ln 2\gamma} \). We are interested in the regime where \( \Gamma \gg \Delta \gg \gamma \), i.e., we have a significant number of well-separated peaks within the overall characteristic width. We define the fineness \( F \) of the atomic distribution as the ratio of the peak separation over the FWHM of the individual peak, which gives \( F = \Delta/\gamma = \Delta/(\sqrt{8 \ln 2\gamma}) \). In the following the Fourier transform \( \tilde{n}(t) \) of \( n(\delta) \) will play an important role. One finds \[ \tilde{n}(t) \propto e^{-t^2/\gamma^2} \sum_{m=-\infty}^{\infty} e^{-(t - n_\alpha \Delta)^2/\gamma^2}, \tag{A6} \] which is also a series of peaks, with overall temporal width \( 1/\gamma \), peak separation \( 2\pi/\Delta \), and individual peak width \( 1/\Gamma \). Under the above assumptions, the peaks are again numerous (within the characteristic overall width) and well separated. To summarize, both \( n(\delta) \) and \( \tilde{n}(t) \) are pulse trains, with inversely proportional separations between the individual pulses, and the global shape of \( n(\delta) \) determines the local shape of \( \tilde{n}(t) \) and vice versa. 3. Absorption The absorption process is described by forward Eqs. (A1) and (A2) coupling \( E_j(z,t) \) and \( \sigma_j(z,t;\delta) \). Plugging the solution of Eq. (A1) into Eq. (A2) one has the following equation for the field This can be rewritten as \[ \left( \frac{\partial}{\partial t} + c \frac{\partial}{\partial z} \right) E_f(z,t) = - \varphi \tilde{\rho} \int_{-\infty}^{t} dt' \tilde{n}(t-t')E_f(z,t'), \] with \[ \tilde{n}(t) = \int_{-\infty}^{\infty} d\delta n(\delta)e^{-i\delta t}. \] Let us consider an incoming light pulse of temporal length \( \tau \). Let us note right away that we are here considering the regime \( \tau \gg L/c \), where \( L \) is the length of the medium. This allows us to neglect temporal retardation effects, i.e., we can neglect the temporal derivative in Eqs. (A7) and (A8). The absorption process then has a duration that is essentially given by \( \tau \). After this time the field is very close to zero until the coherent photon-echo type re-emission at \( t = 2\pi/\Delta \). If we are interested only in the absorption process, we only need to consider values of \( t-t' \) of order \( \tau \) in Eq. (A8). Assuming \( \tau \ll 2\pi/\Delta \), i.e., a pulse duration much shorter than the waiting time for the re-emission, only the central peak of \( \tilde{n} \) from Eq. (A6) will contribute, i.e., \[ \tilde{n}(t-t') \approx e^{-(t-t')\Gamma z^2/2}, \] for \( t-t' \) of order \( \tau \). Assuming that the overall width of the spectral distribution \( \Gamma \) is much larger than the spectral width of the incoming pulse, i.e., \( \Gamma \tau \gg 1 \), \( \tilde{n}(t-t') \) will act essentially like a delta function in the integral in Eq. (A8), giving an approximate equation of the form \[ \frac{\partial}{\partial z} E_f(z,t) = - \frac{\alpha}{2} E_f(z,t), \] with a constant absorption coefficient \( \alpha \). This is easily solved, giving \[ E_f(z,t) = E_f(0,t)e^{-\alpha z/c}. \] Concerning the absolute strength of the absorption, one can show that, under the above assumptions \( \alpha = \alpha \frac{\Delta}{2} \), where \( \alpha \) is the absorption coefficient corresponding to the (central) peaks of \( n(\delta) \). This can be rewritten as \[ \alpha = \frac{\alpha}{2} \sqrt{\frac{\pi}{4 \ln 2}} = 1.064 \frac{\alpha}{2}. \] Hence, for the absorption process, the AFC is indistinguishable from a smooth distribution that would be obtained by a spectral averaging that does not resolve the individual peaks. The pair of \( \pi \) pulses, which are used for storing the excitations in a long-lived ground state and then bringing them back to the excited state, also have the effect of changing the phase pattern of the atomic polarization from forward \( (\sigma_+ \leftrightarrow \sigma_-) \) to backward \( (\sigma_- \leftrightarrow \sigma_+) \), such that it now couples to the backward field \( E_b \). In this case, we will see that this is essential for achieving perfectly readout efficiency, in analogy with the case of CRIB memories [29]. We assume that the time spent in the ground state does not lead to any relative phases between the different frequency components (no inhomogeneous broadening in the ground state). From the point of view of the equations of motion, one can thus treat the two \( \pi \) pulses as being applied essentially simultaneously. We will refer to the corresponding time as \( t=0 \). Absorption thus occurred at negative times, and re-emission will occur at positive times. The backward polarization created at \( t=0 \) is \[ \sigma_b(z,0;\delta) = \sigma_f(z,0;\delta) = \int_{-\infty}^{0} dt' e^{i\delta t'} E_f(z,t'), \] where \( \sigma_b \) (\( \sigma_f \)) is to be understood after (before) the two \( \pi \) pulses. Equation (A14) gives the initial condition for Eqs. (3) and (4). We assume that the field \( E_b \) is zero at \( t=0 \) (the absorption process is completed; if there was a transmitted field it has left the medium). This gives the following equation for the backward field \[ \left( \frac{\partial}{\partial t} - \frac{\partial}{\partial z} \right) E_b(z,t) = - \varphi \tilde{\rho} \int_{-\infty}^{0} dt' \tilde{n}(t-t')E_f(z,t') \] \[ - \varphi \tilde{\rho} \int_{0}^{t} dt' \tilde{n}(t-t')E_b(z,t'). \] The re-emission occurs because \( \tilde{n}(t-t') \) has a peak not only for \( t-t' \) around zero, but also for \( t-t' \) around \( 2\pi/\Delta \). Note that the height of this peak is reduced by a factor \( e^{-\alpha (2\pi/\Delta)^2 z^2} \) with respect to the central peak, cf. Eq. (A6). Around the corresponding point in time, one can apply arguments fully analogous to the ones in the previous subsection. Equation (A15) then simplifies to \[ \frac{\partial}{\partial z} E_b(z,t) = \tilde{\alpha} e^{-\varphi (2\pi/\Delta)^2 z^2} E_f(z,t - \frac{2\pi}{\Delta}) + \tilde{\alpha} E_b(z,t). \] The \( E_f \) term has a factor \( \tilde{\alpha} \) instead of \( \frac{\tilde{\alpha}}{2} \) because the \( t' \) integral in Eq. (A15) is over all of the effective delta function (given by the corresponding peak of \( \tilde{n} \)) for the \( E_f \) (source) term, whereas it is only over one half of the delta function. for the \( E_b \) (absorption) term, as it was in the previous subsection for the absorption of \( E_f \). The solution of Eq. (A16) is \[ E_b(z, t) = e^{-\gamma/2} \int dz' \tilde{e} e^{i2\Delta t/2} E_f(z', t - \frac{2\pi}{\Delta}) \] (A17) Note that \( E_b \) propagates backward so the output field is at \( z=0 \). Using Eq. (A12) one has \[ E_b(0, t) = -E_f\left(0, t - \frac{2\pi}{\Delta}\right) e^{-\gamma/2} \int_0^L dz' \tilde{e} e^{i\Delta t/2} \left(1 - e^{-\Delta t/2}\right). \] (A18) It is interesting to note that the integral over \( z' \) has the same form as in the case of the (backward) CRIB memory [29]. It corresponds to the coherent sum over all possible paths of the photon in the medium, where each path is characterized by its turning point \( z' \). Even though there is absorption along the path, there is a constructive interference effect which leads to the output amplitude potentially being arbitrarily close in magnitude to the input amplitude (for large enough \( \Delta L \)). This interference is not present if the output field is emitted in the forward direction, which would be the case if the two control fields were not applied. Then one would have an integral \[ \int_0^L dz' \tilde{e} e^{i\Delta t/2} e^{-i(x(t') - x(t))/2} = \tilde{a}L e^{-\Delta L/2}, \] (A19) replacing the last factor in Eq. (A18). If one then calculates the efficiency, one finds that it can at most attain 54% for \( \Delta L=2 \), cf. [29]. For the backward propagating mode the achievable memory efficiency is given by, from Eq. (A18), \[ \eta = (1 - e^{-\Delta t})^2 e^{-\gamma/2}, \] (A20) which can be rewritten in terms of the finesse \( F \) and peak absorption \( \alpha \) of the atomic distribution \( n(\delta) \) as [cf. Eq. (5) in paper] \[ \eta = (1 - e^{-\alpha L/F})^2 e^{-\gamma/2}= (1 - e^{-\alpha L/F})^2 e^{-\gamma/2}. \] (A21) There is a tradeoff between absorption (favoring small \( F \)) and dephasing (favoring large \( F \)); however, for large enough \( \alpha L \) and optimized \( F \) the efficiency can be made arbitrarily close to 100% (cf. Figs. 2 and 3 in paper). 5. Phase due to frequency offset Here we will comment on the phase of the output field as a function of the relative frequency detuning between the carrier frequency and the frequency of the peak in the AFC (any of them), cf. Eq. (5) in the paper. If the atomic distribution \( n(\delta) \) is replaced by \( n(\delta-\Delta) \), corresponding to a small frequency offset, then the Fourier transform of \( n(t) \) acquires a phase factor \( e^{i\Delta \delta} \), which leads to a supplementary phase factor \( e^{i2\pi n_L/\Delta} \) for the re-emitted field, cf. Eq. (A18). Note that this phase is modulus the peak separation \( \Delta \). For the rare-earth-doped materials considered here the optical and spin inhomogeneous broadenings are generally uncorrelated. If the physical system would contain correlations between these broadenings, however, there could be a comb structure also on the spin transition.
Incorrectness Logic PETER W. O’HEARN, Facebook and University College London, UK Program correctness and incorrectness are two sides of the same coin. As a programmer, even if you would like to have correctness, you might find yourself spending most of your time reasoning about incorrectness. This includes informal reasoning that people do while looking at or thinking about their code, as well as that supported by automated testing and static analysis tools. This paper describes a simple logic for program incorrectness which is, in a sense, the other side of the coin to Hoare’s logic of correctness. CCS Concepts: · Theory of computation → Programming logic. Additional Key Words and Phrases: Proofs, Bugs, Static Analysis ACM Reference Format: 1 INTRODUCTION When reasoning informally about a program, people make abstract inferences about what might go wrong, as well as about what must go right. A programmer might ask “will the program crash if we give it a large string?”, without saying which large string. In this paper we investigate the hypothesis that reasoning about the presence of bugs can be underpinned by sound techniques in a principled logical system, just as reasoning about correctness (absence of bugs) has been demonstrated to have sound logical principles in an extensive research literature. We also consider the relationship of the principles to automated reasoning tools for finding bugs in software. We explore our hypothesis by defining incorrectness logic, a formalism that is similar to Hoare’s logic of program correctness [Hoare 1969], except that it is oriented to proving incorrectness rather than correctness. Hoare’s theory is based on specifications of the form \[ \{\text{pre-condition}\} \text{code} \{\text{post-condition}\} \] which say that the post-condition over-approximates (describes a superset of) the states reachable upon termination when the code is executed starting from states satisfying the pre-condition (the so-called strongest post). Conversely, we use a specification form \[ [\text{presumption}] \text{code} [\text{result}] \] which says that the post-assertion result be an under-approximation (subset) of the final states that can be reached starting from states satisfying the presumption. The under-approximate triples were studied (with a different but equivalent definition) previously by de Vries and Koutavas [2011] in their reverse Hoare logic, which they used to specify randomized algorithms. Incorrectness logic adds post-assertions for errors as well as for normal termination, and these assertions describe erroneous states that can be reached by actual program executions. Dijkstra [1976] famously remarked that “testing can be quite effective for showing the presence of bugs, but is hopelessly inadequate for showing their absence,” and he made this remark while arguing for the use of mathematical proof to show that bugs don’t occur. Here we obtain a logic where instead one can prove the presence of bugs but not their absence: Because of under-approximation, reasoning is arranged to avoid false positives (bug suggestions that are not true). We will attempt to show that the resulting logic has principles relevant to pragmatic issues in the design of reasoning tools. The simple shift from over to under has a significant impact on what specifications mean. The post-condition in correctness logic constrains what happens, ruling out anything that doesn’t satisfy it, where the result assertion in incorrectness logic indicates the positive fact that certain states, at least those satisfying it, can occur. But the result assertion does not rule out other final states, or even that a pre-state might have no successors (i.e., divergence). As a picture: If the code might be applied to any state satisfying the presumption, then we will be able to reach any state in the result assertion. Or more briefly, from the presumption we achieve the result. In colloquial terms we might say that Hoare triples speak the whole truth, where the under-approximate triples speak nothing but the truth. Incorrectness logic is so basic that it could have been defined and studied immediately after or alongside the fundamental works of Floyd [1967] and Hoare [1969] on correctness in the 1960s. It is the intervening developments in the science and, especially, the engineering of reasoning tools that motivated us to do so. The work in this paper arose as part of an attempt to re-imagine how static reasoning about programs might be done, taking the perspective of bug catching instead of (only) proving absence of bugs. It was motivated, in particular, by work at Facebook on static analysis [Distefano et al. 2019]. Informal, abstract reasoning about the presence of bugs is a fundamental part of communication between people during the code review process, and in their deployment at Facebook mechanized reasoning tools act as bots participating in these conversations: in these deployments they often use symbolic reasoning to identify regressions rather than to prove than none can occur, just as human reviewers frequently do. The paper was also inspired by the use of symbolic execution for testing [Cadar and Sen 2013]. More generally, many practical tools use symbolic reasoning for bug catching, but few of them are accompanied by soundness arguments, and they have sometimes been considered as unprincipled. We suggest that static bug catchers could in future be cast in terms of finding logical proofs of under-approximation in a formal system, analogously to how correctness-oriented tools can be thought of as finding proofs. While we appeal to tool-based considerations as we go along, we attempt to keep the presentation self contained. We give suggestive examples and comments on relevance to automatic program analysis problems, but don’t delve into any specific analyses or tools. 2 UNIFIED PICTURE Although our technical focus in this article is on incorrectness, it will be useful first to describe correctness and incorrectness reasoning in a way that emphasizes their relationship to one another. Readers who prefer seeing examples first can safely skip forward to the next section. Figure 1 depicts the two triples. *Predicates* in the diagram represents the set of subsets of a collection of program states, and the arrows are binary relations. The relation \([-]c[-]\) relates any pair \((p, q)\) of predicates when \([p]c[q]\) holds, and similarly for \([-]c[-]\). \(post(c)\) is actually a function (a single-valued relation), which maps each input predicate to the set of those states reachable upon termination; the others are non-functional relations. The picture is a commuting diagram in the category of sets and binary relations: i.e., \([-]c[-] = post(c)\); \(\supseteq\) and \([-]c[-] = post(c)\); \(\subseteq\), where ‘;’ is sequential composition of binary relations. The diagram can be taken to define \([-]c[-]\) and \([-]c[-]\) in terms of \(post(c)\). A rigorous semantics of these notions will be given later in Section 5. \(post(c)p\) is often called the “strongest” post-condition, because it is the smallest set of states amongst those \(q\) satisfying \([p]c[q]\). This nomenclature reflects the historical accident of focus on the top triangle, and not the equally (we shall attempt to show) natural bottom. \(post(c)p\) is also the largest \(q\) satisfying \([p]c[q]\), what we might call the “weakest under-approximate post”. Below the diagram we list several principles. The under-approximate triple part of \(\land \lor\) symmetry is central: it supports sound reasoning covering fewer than all the paths in a program. The correctness version of the symmetry is true in our framework but the \(\Rightarrow\) implication has sometimes been denied in correctness logics (e.g., \([\text{Gotsman et al. 2011}]\)). Both parts of the \(\uparrow \downarrow\) symmetry are important: these are “rules of consequence” which allow specifications to be adapted to broader contexts. To understand the Principles of Agreement and Denial is it helpful fo appeal to testing terminology. In this picture the regions labelled $u$ and $u'$ represent assertions in an under-approximate triple $[u]c[u']$ and the horizontal lines show the transition relation of the program. We think of the post-condition $o'$ as the “test oracle” in a putative Hoare triple $\{o\}c(o')$. If the question “is this a member of $o'$?” fails for a final state obtained by executing the program from a start state satisfying $o$, then the correctness triple is false. Denial says, as in this picture, that if we have an under-approximate triple taking a subset $u$ of $o$ to $u'$, and part of $u'$ lies outside of $o'$, then our test oracle will fail on it, denying the putative triple; i.e., $\neg \{o\}c(o')$. Agreement gives conditions under which the oracle will be happy: the picture would adjust so that $u'$ was contained in $o'$. Note that Agreement and Denial are logically equivalent. Traditional program testing corresponds to when $u$ and $u'$ are both singleton sets describing a test run. Incorrectness logic uses predicates to describe bigger sets, while remaining under-approximate. In this paper we won’t study correctness and incorrectness triples together, and will use a program statement `error()` to give the capability of test/verification oracles. This is to keep the paper contained; ultimately, it does make sense for them to be used together. There has been important work which uses logical reasoning to help generate test cases [Cadar and Sen 2013]. Property-based testing uses assertions as test oracles [Claessen and Hughes 2000], but as in the discussion above of Agreement and Denial, this is essentially as in Hoare logic: the assertions over-approximate the expected. But, logical principles for showing the presence of bugs have not been as extensively studied as those for showing their absence. Using logic for incorrectness potentially has many of the same benefits as it does for correctness. The essential point is that symbolic, logical reasoning can cover many states at once, even many program paths. While this does give the alluring in-principle ability to cover all paths, to prove the absence of errors, even when fewer than all are covered major advantages can accrue; in particular, it can be the case that symbolically approximating many states can be done more compactly, and efficiently, than enumerating the individual states, and this is the case whether or not we are in the, in practice, comparatively rare situation that every possible state and path is covered. Incorrectness logic is also relevant to specifying interfaces. In the ideal case, assertions describing correctness conditions at exit points in a program (post-assertions) should be over-approximate, while for incorrectness they should be under-approximate. It is important to note that the exact reasoning of the middle line of the diagram is definable mathematically but not computable (unless highly incomputable formulae are used to describe the post). Approximating in either direction provides a way to escape undecidability. Over-approximate reasoning can prove the absence of errors [Cousot and Cousot 1977]: if an over-approximation claims there are no errors, then (modulo assumptions) there will be none when a program is executed. Tools based on over-approximation suffer from false positives, reports of bugs that cannot happen; a state satisfying a post-condition might not be reachable, and apparent errors that follow from it can be false positives. On the other hand, under-approximation is relevant to guaranteeing the presence of errors: if a state leads to an error, and satisfies an assertion describing an under-approximation of the reachable program states, then it can occur in a real execution. Under-approximation removes false positives, but opens the way to false negatives (missed bugs). Finally, the reader might be wondering, why do we need incorrectness reasoning? Can’t we just negate correctness reasoning? That might be the possible in an ideal world where full formal specifications were written for all software beforehand, and where there were no decidability or efficiency issues to contend with. But, the inability to prove an over-approximate spec (whether found by a tool or specified by a human) does not imply an error in a program, and neither does not having found a bug imply that there are none: thus, the need for dedicated techniques for each. 3 BEGINNING EXAMPLES Incorrectness logic provides a perspective on reasoning about programs that, based on our experience describing it to people, appears to take some getting used to. So, we start with an informal warm up session before moving on to the formal development. 3.1 Under-approximating Triples In examples we will use “presumes” to identify an incorrectness logic pre-assertion and “achieves” to identify a post-assertion. This is by analogy with the use of “requires” and “ensures” in some tools for correctness reasoning (e.g., https://en.wikipedia.org/wiki/Java_Modeling_Language). Note that we are not making a concrete recommendation that “presumes” and “achieves” be used in a specification language: these terms are used in code mainly to help us explain examples as we explore the theory. Consider this program, together with the presumption and result. ```c /* presumes: [z == 11] */ if (x is even) { if (y is odd) { z = 42; } } /* achieves: [z == 42] */ ``` Question: is the assertion `z == 42`, the result, an under-approximation of the states reachable by executing this code starting from the presumption? We have found that people very often answer yes, initially. Then we point out, it is not. The reason is that the assertion `z == 42` is satisfied by states where `x` is odd or `y` is even. E.g., the state `[z: 42, x: 1, y: 2]` satisfies `z == 42`, but is not reachable starting from the pre. So, we would say that this is a false under-approximate triple, but that ```c /* presumes: [z == 11] */ if (x is even) { if (y is odd) { z = 42; } } /* achieves: [z == 42 && (x is even) && (y is odd)] */ ``` is a true under-approximate triple. (Similar issues come up for post-conditions associated with errors cause by `error()` statements, by division by 0, by use-after-free, etc. The question arises: what is the post-state when the error occurs?) You might also wonder: why did we include `z == 11` as the pre in the first triple? What if we replaced it with `true`. Would `z == 42` on its own then be a true under-approximation of the post? The answer is yes. At this point folks have exclaimed: What is going on? People are sometimes led to an initial “yes” answer to the question above because they are unwittingly applying the rule of weakening the post-condition. This lets us make an inference like \[ \frac{\{p\} C (q \land r)}{\{p\} C (q)} \] which drops conjuncts. You just can’t do that soundly when reasoning about under-approximation. In fact, there is a fundamental logic for reasoning about under-approximation. Above, when concluding a correct under-approximate post-assertion for our program, you might have noticed that the post-assertion corresponds to only one path through the program: it doesn’t cover them all. We (silently) applied the incorrectness logic part of the principle of \( \land \lor \) Symmetry from before. Not only does incorrectness logic deny weakening the post-condition, it supports other rules like \[ \frac{\{p\} C (q_1 \lor q_2)}{\{p\} C (q_1)} \] which allow us to focus on fewer than all the paths, a feature which is a hallmark of under-approximation. What is more, soundly dropping disjuncts is a useful capability which can be called upon in order to help a reasoning tool scale. ### 3.2 Specifying Incorrectness We can reason about errors by distinguishing result-assertion forms, for normal and erroneous or abnormal termination. For example, consider the following program, which is a variant of one used to illustrate buffer overflows by One [1996]. ```c 1 void foo(char* str) 2 { /* presumes: [*str[]]==s */ 3 achieves: [er:*str[]==s && length(s) > 16 ] */ 4 { char buf[16]; 5 strcpy(buf,str); 6 } 7 } 8 int main(int argc, char *argv[]) 9 { foo(argc[1]); } ``` The specification for `foo()` says that if the length of the input string is greater than 16 then we can get an error (in this case a buffer overflow). (There, we are writing `*str[]==s` to indicate that sequence `s` held as a null-terminated string starting at address `str`.) Remark: it is not necessary that a segmentation fault must occur in C when a buffer overflows (worse can happen). Incorrectness is an abstraction that a programmer or tool engineer decides upon to help in engineering concerns for program construction. Logic provides a means to specify these assumptions, and then to perform sound reasoning based on them, but it does not set the assumptions. ### 3.3 Under-approximate Success Even if we were mainly interested in incorrectness, under-approximate result assertions describing successful computations can help us soundly discover bugs that come after a procedure is called. In particular, if we were to have over-approximate assertions only for successful computations, then our reasoning could go wrong, as the following example illustrates. ```c 1 void mkeven() 2 { /* presumes: [true], wrong achieves: [ok: x==2 || x==4] */ 3 { x=2; } 4 } 5 void usemkeven() 6 { mkeven(); if (x==4) { error(); } } ``` We use ok: before an assertion to indicate that it describes a result for normal, not exceptional, termination of a program. The achieves assertion mkeven() describes an over-approximation of what the procedure produces, including a possibility (x==4) than cannot occur. If we were to use this wrong achieves assertion in usemkeven() to conclude that an error is possible then this would be a false positive warning. For this reason, our formalism will include under-approximate achieves-assertions for both successful and erroneous termination. mkeven() achieves “ok: x==2”, not “ok: x==2 | | x==4”. The possibility of divergence gives rise to many more such examples. If we consider a version of mkeven() with body while (true){}; x=2, then x=4 is an over-approximate post-condition, and it lines up perfectly with the condition to trip the error, but this would again be a false positive. Reasoning about termination is needed to be under-approximate; but, as we shall see, what is needed is not the same as showing termination on all inputs. 4 PROOF SYSTEM We will use a language for simple imperative programs in which a statement error() halts execution and raises a particular error signal, er. error() can be used to define an assert(B) statement that allows correctness (and hence, incorrectness) conditions to be written, in the same way that assert() is defined in terms of abort() in the C programming language. The error() statement leads to abnormal termination, where control never returns to the statement following it. E.g., in \[ x=1; \text{error(); } x=42 \] we know that x=42 will not be executed, and so x will be 1 in the final “abnormal” state. Abnormal control flows impact reasoning about sequential composition, and a standard approach to these flows is to associate assertions with different exit conditions [Clint and Hoare 1972]. Let \( e \) range over a collection of ‘exit conditions’ (or exceptions), to include at least ok (for normal termination) and er (caused by error()). We will consider a specification form \[ [p]C[e;q] \] q under-approximates the states when C exits via e starting from states in p. In this paper we are going to concentrate on a single kind of error, er, arising from error(). This is to concentrate on the essential technical issues. Obviously we could consider and distinguish different kinds of error (say, for division by zero, null pointer exceptions, etc). We treat the assertions, the p, q in \([p]C[e;q]\), semantically in this paper. That is, an assertion is assumed to be a subset of \( \Sigma \), and we don’t fix a language for describing these subsets. The concept of a free variable referred to in proof rules is treated semantically by saying that \( x \) is free in \( p \) if \( p \) is invariant under changing \( x \): i.e., \( \sigma \in p \iff \forall v. (\sigma| x \mapsto v) \in p \), where \( (\sigma | x \mapsto v) \) for the function like \( \sigma \) except that \( x \) maps to \( v \). We sometimes equivalently say that \( p \) is independent of \( x \). Substitution, \( p[e/x] \), is also understood in the evident way as \( \{ (\sigma | x \mapsto [e]\sigma) | \sigma \in p \} \) where \( [e]\sigma \) is the value of expression \( e \) in state \( \sigma \). We use standard logical notation to refer to the complete Boolean algebra structure of the powerset \( P(\Sigma) \) – \( \wedge \) is intersection, \( \vee \) is union, \( \Rightarrow \) is subset inclusion, \( \exists \) is existential quantification, etc. By treating assertions semantically we are essentially appealing to mathematics (or set theory) as an oracle in our proof theory when we use \( \Rightarrow \) in proof rules. We sometime write a quadrule \[ [p]C[ok;q][er;r] \] as shorthand for \([p]C[ok;q]\) and \([p]C[er;r]\) We often write result assertions for normal termination in green and abnormal in red. In cases where the result could be either, as in \([p_i]C[e;q_i]\) we keep the more neutral blue. It’s important to note that the existence of a (consistent) error assertion does not indicate a definite bug in a program. Consider a procedure \( f(x) = \{ \text{assert}(x! = \emptyset); \ldots \} \), with error spec A tool would often choose not to flag an error in \( f() \), instead warning at call sites that supply 0. We don’t expect error specs necessarily to be ephemeral, to be removed as bugs are fixed: a spec like this could be kept in cache, even when part of a complete program that is error free, to be reused to help protect against future regressions when the program is changed. We give two sets of proof rules. Those in Figure 2 are generic ones that we expect to be valid in many models, allowing for different models of states or commands themselves. Two such models (based on traces and on separation) are mentioned in the last section of the paper. Figure 3 contains rules which assume that the states are functions of type Variables → Values. Instead of considering while loops and if statements, we have Kleene iteration $C^*$, assume statements, and nondeterministic choice (+); these let us encode while and if. Kleene iteration does zero or more iterations of $C$ before exiting, behaving as the recursive equation $C^* \equiv \text{skip} + C; C^*$. In the assume(B) statement B is a Boolean expression, which we allow can be built up using the primitives in an otherwise-unspecified first-order logic signature. The commands overall are those built up from primitive commands using choice, iteration and sequential composition. We use the notation $x = e$ for assignment and $e = e'$ for equality. $\text{Mod}(C)$ is the set of variables modified by assignment statements in $C$, and $\text{Free}(r)$ is the set of free variables in an assertion $r$. Normal assignment $x = e$ and $x = \text{nondet}()$ are distinct syntactic forms. In the former, $e$ is an expression built up from a first-order logic signature, can appear within assertions, and is side-effect free. $\text{nondet}()$ does not appear in assertions. Incorrectness logic uses Floyd’s forward-running assignment axiom (see Figure 3) rather than Hoare’s backwards-running one. We actually cannot use Hoare’s, which substitutes into the pre as $[p[e/x]]x = e[ok:p]$, because it is unsound here; for example, in $[42 == y]x = 42[ok: x == y]$ the post-assertion does not under-approximate the states reachable from the pre: a non-reachable state satisfying $x == y$ is one where both $x$ and $y$ denote 3. The axioms for assume and skip give the expected assertions for normal termination, but specify false (the empty set of states) for abnormal. false is a valid result assertion for either normal or abnormal termination, for any program, and we have included an axiom to that effect. Incorrectness logic’s rule of consequence lets us enlarge (weaken) the pre and shrink (strengthen) the post-assertion. As we indicated earlier, this lets us drop disjuncts from the post, using the implication $q \Rightarrow q'$. Conversely, we can drop conjuncts in the pre: $$ [p_1 \land p_2]C[e; q] \\ [p_1]C[e; q] $$ Enlarging the pre was used in the Abductor tool ([Calcagno et al. 2011]), which led to Facebook Infer, when guessing pre-conditions in programs with loops. This operation was unsound in the over-approximating logic used there, and was one of the reasons for a re-execution step which filtered out unsound pre-conditions. This step would be sound in incorrectness logic. The first rule for sequencing is for short-circuiting, when error() happens within the first statement, and the second covers sequencing when the first command terminates normally. The Iterate zero rule corresponds to immediate exit from the loop. It shows that any assertion is a valid under-approximate invariant for Kleene iteration; loop invariants don’t play a central role in under-approximate reasoning like they do for over-approximate. The Iterate non-zero rule uses $C^*; C$ rather than $C; C^*$ to help reasoning about cases where an error is thrown inside an iteration: In that case some number of successful iterations will occur, and the error will be thrown on the last iteration. To reason about such cases you can first find a result assertion for normal termination, the “frontier” before then error-throwing iteration, and then reason about errors that flow from the frontier in the next step. An example showing this capability will be used in Section 6.1, and this reasoning pattern will be used in the completeness proof in Section 5.1. We can derive useful rules for choice and iteration using the disjunction rule. <table> <thead> <tr> <th>Derived Unrolling Rule</th> <th>Derived Rule of Choice</th> </tr> </thead> <tbody> <tr> <td>$[p]C^i[e; q_i], \text{ all } i \leq \text{bound}$</td> <td>$[p]C_1[e; q_1] \land [p]C_2[e; q_2]$</td> </tr> <tr> <td>$[p]C^* e; \bigvee_{i \leq \text{bound}} q_i$</td> <td>$[p]C_1 + [p]C_2[e; q_1 \lor q_2]$</td> </tr> </tbody> </table> In the Unrolling Rule $C^i$ is the $i$-fold sequential composition, where $C^n = \text{skip}$ and $C^{n+1} = C; C^n$. The rule says that one of the things that iteration can do is execute its body $i$ times. The Unrolling rule states that the states are functions of type Variables → Values. Rule gives us a capability similar to symbolic bounded model checking [Clarke et al. 2004]. It is a simple and surprisingly effective way to discover some post-conditions for a loop, but in general stronger reasoning is needed (as provided by the Backwards Variant rule). An important point is that $[\text{presumption}]c[e: \text{result}]$ expresses a reachability property that involves termination. Every state in the result is reachable from some state in the presumption. This reachability property does not imply that a loop must terminate on all executions. Instead, it establishes that enough paths terminate to cover all the states in the result assertion, while allowing that other paths might lead to divergence. The Backwards Variant proof rule is designed with this in mind. $p(\cdot)$ in the rule is a parametrized predicate (a function from expressions to predicates). The requirement that $n$ be fresh in the rule means that it is a variable not free in $C$ or $p(\cdot)$. The rule is similar to proof rules for proving program termination which appeal to a “variant” that decreases on each loop iteration [Apt 1981; Harel 1980], except that it reflects the backwards nature of this property: the variant, the parameter to $p$, goes down when executing backwards rather than forwards. A forwards variant of the rule is possible to formulate, but is not very useful in incorrectness logic, since $[\exists n.p(n) \land \text{nat}(n)]C^{*}[ok:p(0)]$ is automatically true without any premises: from a state satisfying the post we can get back to the pre by choosing zero iterations and using 0 to witness $\exists n$. Section 6.1 shows reasoning about a loop which contains both terminating and non-terminating executions using the Backwards Variant rule. The reachability property is intuitively related to “liveness”, which says that “something (good) will eventually happen” [Lamport 1977]. Entertainingly, in our case the “good” might be a bug. We can cast the property as stated in terms of something happening by reading a spec backwards: for every state in the result, it is possible to eventually reach a state in the pre by executing backwards. Reading forwards is trickier, but possible: if we explore executions from all the start states described by a pre, then eventually any given state in the result will be encountered. This exploration could be relative to an oracle to enumerate the pre-states, and it would dovetail and backtrack executions on the different states so divergence or nondeterminism from one state does not block other explorations. Note that the “eventually” here does not concern all paths, and appears related technically to what is known as an “existential liveness property” [Manolios and Trefler 2001]. In contrast, the over-approximate triple $[\text{pre}]C[\text{post}]$ describes a safety property, that “nothing bad will happen”, where “bad” is delivering a final state outside the post, and this does not require termination of any paths. The Iterate zero rule can be derived from the Backwards Variant rule together with Consequence and Empty under-approximates by choosing using $p(\cdot)$ of the form $\lambda n.\text{if } n > 0 \text{ then false else } p$. We have not attempted to formulate a minimal set of proof rules, but in Section 5.1 we shall prove a completeness theorem indicating that no proof rules are missing. A version of the Backwards Variant rule is also present in reverse Hoare logic [de Vries and Koutavas 2011], as are most of our other rules for ok termination. They use a language with an infinitary syntax, and include an infinitary version of the disjunction rule. While we have not included an infinitary rule, the expressive power of infinite disjunctions is essentially used in selecting a variant assertion in the proof of completeness (Theorem 6). We do not include the dual of the disjunction rule, the rule with $\land$ in place of $\lor$, because it is unsound for under-approximation. For the program $$C = (\text{assume } x==1 ; x = 88) + (\text{assume } x==2 ; x = 88)$$ we have \([x == 1]C[ok: x == 88]\) and \([x == 2]C[ok: x == 88]\), but the conjunction \(x == 1 \land x == 2\) is \textit{false}, and we don’t have \([false]C[ok: x == 88]\) because \textit{false} is the post of \(C\) applied to \textit{false}, and \(x == 88\) is not a subset of \textit{false}. The rules of \textit{Substitution} and \textit{Constancy}, as well as \textit{Consequence}, are important for adapting specifications for use in different contexts, as will be seen in examples in Section 6.4. The Local Variable rule is similar to one from Hoare logic [Apt 1981], except that we have \(\exists y\) in the post-assertion where the Hoare rule omits the \(\exists y\) while requiring \(y \notin \textit{Free}(q)\). In over-approximate reasoning one can move from \(q\) to \(\exists y.q\) using the rule of Consequence, but that step is not available in under-approximate reasoning. If we did not include \(\exists y\) then the rule would be too weak in many examples. The simple \begin{align*} \text{Derived Local Variable Rule} \\ [p]C[e: q] \quad \exists x.p \quad \exists x.q \\ \exists x.C[e: \exists x.q] \end{align*} comes in handy. It can be derived using the Local Variable rule, Consequence, and Substitution I. We finish this section with an exercise: deriving an axiomatic treatment of \texttt{assert} statements based on the encoding in Figure 2. The rule for + gives us these two quadruples: \begin{align*} [p \land B]\texttt{assert}(B)[ok: (p \land B)][er: false] \\ [p \land \neg B]\texttt{assert}(B)[ok: false][er: p \land \neg B] \end{align*} For example, \begin{align*} [x \text{ is even}]\texttt{assert}(x \text{ is even})[ok: x \text{ is even}][er: false] \\ [x \text{ is odd}]\texttt{assert}(x \text{ is even})[ok: false][er: x \text{ is odd}] \end{align*} In a symbolic execution tool, these sorts of axiom might be used in case we wish to call a theorem prover at branch points of if statements, in order to prune paths in the search for bugs. A different derived axiom might be useful in some circumstances, in case we wish to postpone the theorem prover call. Namely, suppose we have a presumes assertion before an \texttt{assert} statement \begin{align*} [p]\texttt{assert}(B)[??] \end{align*} and we don’t know if \(p\) implies \(B\) or \(\neg B\). We can push information to the result assertions, as follows: \begin{align*} [p]\texttt{assert}(B)[ok: (p \land B)][er: p \land \neg B]. \end{align*} For example, \begin{align*} [true]\texttt{assert}(x \text{ is even})[ok: x \text{ is even}][er: x \text{ is odd}]. \end{align*} 5 SEMANTIC FOUNDATION We provide a semantic foundation for the above. Readers who are more interested in seeing the proof rules in action can skip forward to the examples in the next section. 5.1 Relations We presume we are given a set \(\Sigma\) of states, and predicates \(p, q, \) etc denote subsets of \(\Sigma\). Much of our development works for arbitrary \(\Sigma\), but to interpret the assignment statement we consider states to be of the form \(\Sigma = [\textit{Variables} \rightarrow \textit{Values}]\) where a state maps variables to values. To reason about termination we further assume that \textit{Values} contains the set of natural numbers. Generic Semantics for arbitrary state sets \( \Sigma \) \[ [C]\epsilon \subseteq \Sigma \times \Sigma \] \[ [B] : \Sigma \rightarrow \text{Bool} \] \[ [\text{skip}]\text{ok} = \{(\sigma, \sigma) \mid \sigma \in \Sigma\} \] \[ [\text{skip}]\text{er} = \emptyset \] \[ [\text{error()}]\text{ok} = \emptyset \] \[ [\text{error()}]\text{er} = \{(\sigma, \sigma) \mid \sigma \in \Sigma\} \] \[ [\text{assume } B]\text{ok} = \{(\sigma, \sigma) \mid [B]\sigma = \text{true}\} \] \[ [\text{assume } B]\text{er} = \emptyset \] \[ [C^*]\epsilon = \bigcup_{i \in \text{Nat}} [C^i]\epsilon \] \[ [C_1; C_2]\epsilon = \{(\sigma_1, \sigma_3) \mid \exists \sigma_2. (\sigma_1, \sigma_2) \in [C_1]\text{ok} \text{ and } (\sigma_2, \sigma_3) \in [C_2]\epsilon\} \] \[ \bigcup \left( \text{if } (\epsilon = \text{ok}) \text{ then } \emptyset \text{ else } ((\sigma_1, \sigma_2) \mid (\sigma_1, \sigma_2) \in [C_1]\text{er}) \right) \] Semantics of mutation and local variables \[ \Sigma = \text{Variables} \rightarrow \text{Values} \] \[ [e] : \Sigma \rightarrow \text{Values} \] \[ [x = e]\text{ok} = \{(\sigma, (\sigma \mid x \mapsto [e]\sigma)) \mid \sigma \in \Sigma\} \] \[ [x = e]\text{er} = \emptyset \] \[ [x = \text{nondet()}]\text{ok} = \{(\sigma, (\sigma \mid x \mapsto v)) \mid \sigma \in \Sigma, v \in \text{Values}\} \] \[ [x = \text{nondet()}]\text{er} = \emptyset \] \[ [\text{local } x. C]\epsilon = \{(\sigma \mid x \mapsto v), (\sigma' \mid x \mapsto v)) \mid (\sigma, \sigma') \in [C]\epsilon, v \in \text{Values}\} \] Fig. 4. Relational Denotational Semantics **Definition 1 (Post and Semantic Triples).** For any relation \( r \subseteq \Sigma \times \Sigma \) and predicate \( p \subseteq \Sigma \) define - The post-image of \( r \), \( \text{post}(r) \in P(\Sigma) \rightarrow P(\Sigma) \): \[ \text{post}(r)p = \{\sigma' \mid \exists \sigma \in p. (\sigma, \sigma') \in r\} \] - The under-approximate triple: \[ [p]r[q] \text{ is true } \text{ iff } \text{post}(r)p \supseteq q \] - The over-approximate triple (Hoare triple): \[ [p]r[q] \text{ is true } \text{ iff } \text{post}(r)p \subseteq q \] First, we remark that this semantics validates the discussion in Section 2. **Theorem 2.** All of the listed properties in Figure 4 are true of this semantics. There is an alternate characterization of under-approximate triples in terms of the previously-stated reachability property, which is in fact an equivalence that is useful when doing semantic calculations. **Lemma 3 (Characterization).** The following are equivalent: 1. \([p]r[q] \text{ is true}\) 2. Every state in the result is reachable from some state in the pre: \( \forall \sigma_q \in q. \exists \sigma_p \in p. (\sigma_p, \sigma_q) \in r \) De Vries and Koutavas [2011] take (2) in this lemma as the semantics of triples, rather than the equivalent from Definition 1. Relations give a particularly simple denotational (i.e., compositional) semantics of programs, as in Figure 4. In this semantics each program \( C \) is associated with two relations, \([C]\text{ok}\) and \([C]\text{er}\), describing state transitions for successful and erroneous computations. The semantics of $C^*$ is not literally compositional as presented, but $[C^*]$ is defined in terms of $[C]$ so it expands to a compositional definition. $[C^*]$ can also be presented as the least fixed-point of a function of the form $\lambda C.\text{skip} + C$; $r$ using lattices of relations ordered by graph inclusion. This relational semantics treats divergence in an implicit way, in that there are no explicit $\perp$’s. An always-divergent program such as while(\text{true}) do \text{skip} denotes the empty relation, and the semantics satisfies the identity $C = C + \text{diverge}$. For readers familiar with subtleties that arise in the semantics of nondeterminism [Apt and Plotkin 1986; Cousot 2002], particularly when reasoning about the liveness property of total correctness (over-approximation plus termination), it might be surprising that we can use such a simple semantics. The relational semantics is known to work well for partial correctness, and it turns out that it is also suitable for studying the reachability property of under-approximate triples. We can connect the relational semantics to the proof system of incorrectness logic by interpreting the proof-theoretic specifications in terms of the semantic triples. **Definition 4 (Interpretation of Specifications).** $[p]C[e;q]$ is true iff the semantic triple $[p][([C]e)q]$ holds. The proofs for the ok cases in the following soundness and completeness results can be as in reverse Hoare logic [de Vries and Koutavas 2011], and most can also be obtained from arguments in dynamic logic [Harel 1979]. We will briefly sketch some of these cases along with the er ones to keep the paper contained. **Theorem 5 (Soundness).** The relational semantics in Figure 4 validates all the rules in Figures 2 and 3: each axiom is true and each inference rule preserves truth. **Proof:** The soundness of the first two iteration rules follow from the true equivalence $C^* \equiv \text{skip} + C^*; C$. For the Backwards Variant rule we will use the Characterization Lemma. Assuming we have $$\sigma$$ satisfying $\exists n.p(n)$ we wish to show that there is $\sigma'$ satisfying $p(0)$ which $(C)^*$ transforms to $\sigma$ Starting from $\sigma$, let $j$ be a value of $n$ which witnesses the existential. If $j = 0$ we are done, we can choose zero iterations of $(C)^*$. Otherwise, the premise of the rule says that applying $C$ once backwards gives us at least one $\sigma_0$ satisfying $p(j - 1)$. If $j - 1$ is 0 then we are done. Else, we repeat this step and iterate again backwards from $\sigma_0$ to obtain some $\sigma_1$ where $p(j - 2)$ holds. Continuing this process will eventually in a finite number of steps deliver $p(0)$. Amongst the variable rules we give the proof for the Local Variable rule; our rule, which follows Apt [1981], is slightly different from the one in reverse Hoare logic, which relies on alpha-renaming bound variables. Suppose $[p]C(y/x)[e;q]$ and $(\sigma_q \mid x \mapsto v, y \mapsto v_y) \in \exists y.q$. Then $(\sigma_q \mid x \mapsto v, y \mapsto v_2) \in q$ for some $v_2$. We execute $C(y/x)$ backwards and get $(\sigma_p \mid x \mapsto v, y \mapsto v_1) \in p$ by the Characterization Lemma. Since $p$ is independent of $y$ we can set $y$ back to $v_y$ and it will still be in $p$: $(\sigma_p \mid x \mapsto v, y \mapsto v_y) \in p$. This sequence of steps can be mimicked in the semantics of local x.C, stepping from $(\sigma_q \mid x \mapsto v, y \mapsto v_y)$ via backwards finalization to $(\sigma_q \mid x \mapsto v_2, y \mapsto v_y)$, then backwards via $C$ to $(\sigma_p \mid x \mapsto v_1, y \mapsto v_y)$, and then via backwards initialization to $(\sigma_p \mid x \mapsto v, y \mapsto v_y)$. We already argued above that $(\sigma_p \mid x \mapsto v, y \mapsto v_y) \in p$, so this gives us the truth of $[p]\text{local x.C}[e;3y.q]$ by the Characterization Lemma. The argument for the other variable rules similarly appeals to the Characterization Lemma. The arguments for + and ; are immediate from the semantic definitions. For assignment soundness follows from the fact that Floyd’s axiom expresses the strongest post-condition, which is therefore also an under-approximation. Similar is true for skip, error( ), x=nondet( ) and assume(B). Next we need a condition on predicates. A subset $p \subseteq \Sigma(=\text{Variables} \rightarrow \text{Values})$ might depend on all variables, but we need to be able to select a fresh variable $y$ not in a given assertion in order to apply the Local Variable rule in the proof of completeness. So, suppose that Variables is countably infinite, and define a predicate $p$ to be finitely-supported if it is independent of all but a finite number of variables. Typically in applications, assertions will be written syntactically as finite expressions involving finitely many variables, so being finitely-supported is not a drastic restriction. **Theorem 6 (Completeness).** Every true triple involving finitely-supported predicates is provable. This theorem relies on us using semantic (subset of $\Sigma$) rather than syntactic predicates, with an oracle to decide implications. It does not contradict undecidability results, but rather confirms a sense in which no proof rules for programs are missing. [To cognoscenti: semantic predicates let us assume (or dodge the issue of) “expressiveness” [Cook 1978] used in completeness for Hoare logics, and requiring that Values contains the natural numbers builds in the “arithmetical” interpretation idea used in arguments for liveness proof rules [Harel 1979]. Our use of semantic predicates has precedent, e.g., in the metatheory of separation logic [Calcagno et al. 2007; Yang 2001] and embeddings of program logics in proof assistants [Nipkow 2002].] **Proof:** We need to show that $[p]C[e;q]$ is provable on the assumption that it is true, and we do this by induction on the structure of $C$. The base cases for assignment, error and assume follow at once using the rule of consequence and the fact that the axioms express strongest post-conditions. For choice, if $[p]C_1 + C_2[e;q]$ is true then we know that $q$ is a subset of $\text{post}(\llbracket C_1 + C_2 \rrbracket e)p$, which is equal to $\text{post}(\llbracket C_1 \rrbracket e)p \lor \text{post}(\llbracket C_2 \rrbracket e)p$. By induction we know that each $[p]C_i[e;\text{post}(\llbracket C_i \rrbracket e)p]$ is provable, and so the provability of $[p]C_1 + C_2[e;q]$ follows by the disjunction rule and consequence. For sequencing, in case $e = ok$ the result follows by induction using the first sequencing rule, consequence, and that $\text{post}(\llbracket C_1; C_2 \rrbracket ok)p = \text{post}(\llbracket C_2 \rrbracket ok)\text{post}(\llbracket C_1 \rrbracket ok)p$. In case $e = er$ we use induction, consequence and the rule of disjunction together with the equality $\text{post}(\llbracket C_1; C_2 \rrbracket er)p = (\text{post}(\llbracket C_2 \rrbracket er)\text{post}(\llbracket C_1 \rrbracket ok)p) \lor \text{post}(\llbracket C_1 \rrbracket er)p$. For iteration first we do the proof for $e = ok$. Supposing $[p](C)^* [ok; q]$ is true, we define $p(n) = \{\sigma \mid \text{you can get back from } \sigma \text{ to some state in } p \text{ by executing } C \text{ backwards } n \text{ times}\}$. Note that $p(0) = p$ by this definition. From the definition of $p(n)$ it is evident that $[p(n) \land \text{nat}(n)]C[ok; p(n + 1) \land \text{nat}(n)]$ is true, and hence it is provable by induction hypothesis. We apply the Backwards Invariant rule and then Consequence using $q \Rightarrow \exists n.p(n)$, which is a true implication because of the Characterization lemma. This shows that $[p](C)^* [ok; q]$ is provable. (We use $n$ to describe the number of iterations in a similar way to Harel [1979], except that he appeals to Gödel encoding, and to de Vries and Koutavas [2011], who use an infinitary disjunction.) Now, for $e = er$ we use the idea is that if an error is thrown then some number of successful iterations happens first, followed by error happening on thenext (last) iteration. We use the rule Iterate non-zero to deal with this case. So, suppose $[p](C)^* [er; q]$ is true and define frontier to be the reachable states for normal termination; i.e., $\text{frontier} = \text{post}(\llbracket C \rrbracket ok)p$. By the just-proven completeness case for iteration and normal termination, we know that $[p](C)^* [ok; \text{frontier}]$ is provable. Now, $[\text{frontier}]C[er; q]$ must be true (note the absence of $\ast$), or else the beginning assumption that $[p](C)^* [er; q]$ could not be. By induction hypothesis we know $[\text{frontier}]C[er; q]$ is provable, and we can use Sequencing (normal) and Iterate non-zero to conclude that $[p](C)^* [er; q]$ is provable. Our final case is local variables. Suppose \([p]_{\text{local}} x.C[e;q]\) is valid. We pick \(y\) independent of \(p\) and not free in \(C\) (\(p\) being finitely supported guarantees \(y\) exists), and claim that (*) \(q \subseteq \exists y. \text{post}(\llbracket C(y/x) \rrbracket e)p\). Postponing proof of (*), \([p]C(y/x)[e; \text{post}(\llbracket C(y/x) \rrbracket e)p]\) is provable by induction hypothesis, and then we can use the Local Variable Rule together with (*) and the rule of Consequence to conclude that \([p]_{\text{local}} x.C[e;q]\) is provable. [Note: induction hypothesis does not literally apply because \(Apt\ 1981\) is valid. We pick \(Dijkstra\ 1976\) means that there exists \(Apt\ 1981\); were not needed for the completeness \(\])\]. We are left to prove (*). If \(q\) is empty we are done. If \(q\) is nonempty then the validity of \([p]_{\text{local}} x.C[e;q]\) means that there exists \((\sigma_p \mid x \mapsto v_0, y \mapsto v), (\sigma_q \mid x \mapsto v_0, y \mapsto v) \in \llbracket \text{local } x.C \rrbracket\) with \((\sigma_p \mid x \mapsto v_0, y \mapsto v) \in p\) and \((\sigma_q \mid x \mapsto v_0, y \mapsto v) \in q\). This transition is witnessed (for some \(v_1, v_2\)) by the steps in the semantics of \(\text{local } x.C\) from \[ (\sigma_p \mid x \mapsto v_0, y \mapsto v) \text{ via initialization to } (\sigma_p \mid x \mapsto v_1, y \mapsto v), \text{ via } C \text{ to } (\sigma_1 \mid x \mapsto v_2, y \mapsto v), \text{ and via finalization to } (\sigma_q \mid x \mapsto v_0, y \mapsto v). \] Since \((\sigma_p \mid x \mapsto v_0, y \mapsto v) \in p\) and \(p\) is independent of \(y\) we also have \((\sigma_p \mid x \mapsto v_0, y \mapsto v_1) \in p\), mimicking the initialization step above. We can mimic the remaining steps by moving from \[ (\sigma_p \mid x \mapsto v_0, y \mapsto v_1) \text{ via } C(y/x) \text{ to } (\sigma_q \mid x \mapsto v_0, y \mapsto v_2) \in \text{post}(\llbracket C(y/x) \rrbracket e)p. \] This shows \((\sigma_q \mid x \mapsto v_0, y \mapsto v) \in \exists y. \text{post}(\llbracket C(y/x) \rrbracket e)p\), and (*) follows. The rules of Substitution and Constancy from Figure 3 were not needed for the completeness proof. They are used in Section 6.4 to adapt specifications to calling contexts. The substitution rules are suitable for use with parameterless procedures, but additional rules are needed to deal with parameters. This has been a notoriously subtle problem-area in Hoare logics [Apt 1981; Cook 1978], and a thorough treatment of incorrectness logic with procedures would be worthwhile. 5.2 Predicate Transformers Predicate transformers, functions that map predicates to predicates, are a fundamental semantic tool in program logic and analysis. In this section we find that: 1. forwards transformers, which form the basis for program verification and (especially) program analysis tools, are well behaved in incorrectness logic; 2. backwards transformers, which have been used extensively in tools and in program refinement [Back and von Wright 1998; Dijkstra 1976], do not always exist for incorrectness logic (at least in standard forms). Forwards Transformers. The post-condition operator \(\text{post}(r)p\) can be given an alternate characterization as the strongest predicate satisfying the Hoare triple \([p]r[q]\). This is usually called the strongest post-condition, but we will call it strongest-over-approximate post to distinguish from the opposite notion, the weakest under-approximate post. **Definition 7.** For \(r \subseteq \Sigma \times \Sigma\): - **StrongestOverPost**(\(r\))\(p = \bigwedge\{q \mid [p]r[q] \text{ holds}\} - **WeakestUnderPost**(\(r\))\(p = \bigvee\{q \mid [p]r[q] \text{ holds}\} **Proposition 8.** **StrongestOverPost**(\(r\)) = **WeakestUnderPost**(\(r\)) = \(\text{post}(r)\) This proposition gives a starting point for defining under-approximating program analyses. We explain this in the key cases of iteration and choice, which encapsulate the issues of undecidability and path explosion that program analyses need to deal with. The strongest post for iteration can be defined by appeal to loop invariants. \[ \text{post}(\llbracket C^* \rrbracket \mathbf{ok}) p = \land \{ I \mid p \Rightarrow I \land (I \models C[I] \text{ is true}) \} \] This equation can be proven, in the left-to-right direction, from soundness of the Hoare proof rule for invariants, and from right-to-left by selecting \( I \) to be the set of all states reachable in some number of executions of \( C \) from \( p \). A different definition is possible with under-approximate triples. \[ \text{post}(\llbracket C^* \rrbracket \epsilon) p = \lor_{i \in \text{Nat}} \{ q \mid [p]C^i[q] \text{ is true} \} \] That this equation is true can be proven by selecting \( q = \{ s \} \) for each of the reachable states \( s \), and observing that when \( s \) is reachable we must get there by some number \( i \) of iterations. These two (equivalent) definitions of the iteration predicate transformer present different compromise possibilities that reasoning tools can take in the face of undecidability. For over-approximation, if we discover a loop invariant then the first equation tells us that we will over-approximate the post [Cousot and Cousot 1977]. This is nontrivial, and tends to require the invention of remarkable abstract domains and widening operators which are generally not yet available in every situation. For under-approximation, the second equation tells us that the simple option of limiting the loop unrolls can be used \[ \text{post}(\llbracket C^* \rrbracket \epsilon) p = \lor_{i \leq \text{bound}} \{ q \mid [p]C^i[q] \text{ is true} \} \] This is an alternate predicate transformer semantics where the calculated post is a subset of the exact one. While blunt, this approach does not require human invention for every new analysis problem, and presents less of a bottleneck as regards the availability of possibly scarce human expertise. The idea that you can under-approximate via bounded loop unrolls is well known. We have made these points only to exemplify how incorrectness logic’s principles fit well with (under-approximate) reasoning intuition, in a complementary way to how Hoare logic fits for correctness. Turning now to nondeterministic choice, we have \[ \text{post}(\llbracket C_1 + C_2 \rrbracket \epsilon) p = \text{post}(\llbracket C_1 \rrbracket \epsilon) p \lor \text{post}(\llbracket C_2 \rrbracket \epsilon) p \] Even if loops are bounded to remove infinite executions, we can still obtain an explosion of paths when + is used to model conditionals. A standard technique in program analysis is to avoid disjunctions by keeping a single or few abstract states at each program point. Theoretically, this can be seen as selecting a “join operator” \( \lor \) that over-approximates disjunction: \( p \lor q \Rightarrow p \lor q \). For under-approximate reasoning we need to do the reverse: consider \( \lor \) where \( p \lor q \Rightarrow p \lor q \). Then, we can define \[ \text{post}(\llbracket C_1 + C_2 \rrbracket \epsilon) p = \text{post}(\llbracket C_1 \rrbracket \epsilon) p \lor \text{post}(\llbracket C_2 \rrbracket \epsilon) p \] The general point is that a predicate transformer semantics \text{post} with just these clauses in place of the standard ones produces correct under-approximate post-states. Often in program analysis a set of abstract states is used to represent a disjunction, and a representation of the disjunction of two of the sets is their union. In this case, a valid implementation of \( \lor \) is simply to trim the resulting union so that it stays smaller than a given threshold. That is the approach taken in Infer.Pulse, a program analyzer for object lifetimes in production at Facebook. There is much more to producing a program analysis than changing the predicate transformer semantics in this way. In particular, compositional reasoning, where pre- as well as post-assertions are inferred, is important for scalability and incrementality [Calcagno et al. 2011; Distefano et al. 2019; O’Hearn 2018]. We will not define a compositional analysis method in this paper, but will comment on the connection between under-approximate triples and the concept of procedure summary during our discussion in the next section. Backwards Transformers. Where the forwards transformers for under-approximation are similarly well behaved as their over-approximate cousins, the same is not true for backwards. **Fact 9.** Valid presumptions need not exist: Given a relation $r$ and assertion $q$, there need not exist any $p$ such that $[p]r[q]$. For example, there is no $p$ making $[p]x = 41[\text{ok}; \text{true}]$ hold. One might try to remedy this problem by adding a special predicate (say, $\top$) to assign as the pre when no appropriate state set exists. However, this simple tack is not enough: even when valid presumptions exist, there need not be a smallest (strongest) one. The example $C = (\text{assume } x = 1 ; x = 88) + (\text{assume } x = 2 ; x = 88)$ from earlier has $x = 1$ as $x = 2$ are valid pre’s for result $\text{ok} : x = 88$, but their conjunction is not. While strongest under-approximate presumptions do not exist in general, this does not mean that backwards reasoning is impossible to use. We can use standard backwards transformers, which were designed to discover over-approximate triples, to generate pre-assertions, and then reason forwards to generate sound under-approximate post-assertions. We illustrate with an example in Section 6.3. ### 5.3 Other Characterizations We described the under-approximate triple directly using predicate transformers, and gave an equivalent characterization which we called the reachability property. de Vries and Koutavas go the other way around and take the reachability property as the definition [de Vries and Koutavas 2011]. Other equivalent characterizations are possible using a number of logical theories that have been developed over the years. Relational and Kleene Algebra. We can describe the under-approximate triple using the theory of binary relations, and the dual of an encoding of over-approximate triples suggested by Hoare in work on Concurrent Kleene Algebra [Hoare et al. 2011]; he suggested to read $\{p\}r\{q\}$ as $p; r \subseteq q$, and we will reverse $\subseteq$. Instead of working at the algebraic we will stick with the particular model of relations. To formulate the connection we use the following mapping of predicates to binary relations. **Definition 10.** If $p \subseteq \Sigma$ then let $\text{make}(p) = \{(\sigma, \sigma') | \sigma' \in p\}$. **Fact 11.** Let “;” denote composition of binary relations in diagrammatic order. Suppose $r \subseteq \Sigma \times \Sigma$ is a relation and $p, q \subseteq \Sigma$ are predicates. - $(p)r[q]$ holds iff $\text{make}(p); r \subseteq \text{make}(q)$. - $[p]r[q]$ holds iff $\text{make}(p); r \supseteq \text{make}(q)$. Based on this characterization we can make a further connection to the theory of Kleene Algebra with Tests (KAT, [Kozen 2000]). A model of KAT is an algebraic structure (an idempotent semiring with additional axioms) including operations for sequential composition and nondeterministic choice, and equipped with an embedding of a Boolean algebra that sends disjunction to $+$ and conjunction to sequential composition. A standard model of KAT takes binary relations on a state space $\Sigma$ as the carrier of the algebra, and embeds the Boolean algebra $P(\Sigma)$ into it via a mapping $\text{assume}(\cdot)$ that sends a predicate $p$ to the subset of the identity relation with domain $p$. Then $\text{make}(p)$ corresponds to the sequential composition $\top; \text{assume}(p)$, where $\top$ is the everywhere-true binary relation. The under-approximate triple can then be represented in KAT as $\top; \text{assume}(p); r \supseteq \top; \text{assume}(q)$, where $a \supseteq b$ is defined as $a + b = a$. Dynamic Logic. Dynamic logic is a modal logic with an operator \(\langle C\rangle p\) which says that, from the current state, it is possible to transition via program \(C\) to a state satisfying \(p\) [Harel et al. 2000]. The dual, \([C]p\), says that all ways of transiting via \(C\) satisfy \(p\). In terms of our relational semantics: **Definition 12.** Suppose \(r \subseteq \Sigma \times \Sigma\) is a relation and \(p \subseteq \Sigma\) is a predicate. - \(\langle r\rangle p\) is true in state \(\sigma\) iff \(\exists \sigma' \in p. (\sigma, \sigma') \in r\). - \([r]p = \neg \langle r\rangle \neg p\). - \(r^{-1}\) denotes the reversal of relation \(r\). \(r^{-1}\) gives us an alternate way to describe the \(\text{post}(\cdot)\) predicate transformer, and this provides another way to describe the over-approximate and under-approximate triples. **Fact 13.** - \(\langle r^{-1}\rangle p = \text{post}(r)p\) - \([p]r[q]\) holds iff \(q \subseteq \langle r^{-1}\rangle p\) holds (iff \(p \Rightarrow [r]q\) holds) - \([p]r[q]\) holds iff \(q \Rightarrow \langle r^{-1}\rangle p\) holds Dynamic logic is a general logic that includes negation, conjunction, nestings of modal operators, etc. The principles of Figure 1 can be seen as true formulae of dynamic logic. There has been work on reasoning about incorrectness using dynamic logic [Rümmer and Shah 2007], but it is quite different to that here. They focus on disproving total correctness statements for deterministic programs, which is to say proving formulae of the form \(\neg (\text{pre} \Rightarrow \langle r\rangle \text{post})\), rather than on under-approximation and on the connection to problems of program analysis. It seems likely that most if not all of our proof rules for \(\text{ok}\) termination, as well as soundness and completeness results (and incidentally those of de Vries and Koutavas [2011]), could be derived by embedding into dynamic logic. In particular, dynamic logic gives a pleasant explanation for the backwardness in the proof rule for variants. Harel [1979] formulates existential reasoning with formulae like \(p(n+1) \land \text{nat}(n) \Rightarrow \langle r\rangle p(n) \land \text{nat}(n)\). In terms of the encoding of total correctness for deterministic programs as \(\text{pre-cond} \Rightarrow \langle r\rangle \text{post-cond}\), this describes how a variant decreases on each forwards loop iteration. But if we replace the \(r\) by \(r^{-1}\), and regard the left-hand side of the implication as the result assertion and the right as the presumption, then the formula for decreasing \(n\) is equivalent to the premise of the Backwards Variant rule. Harel [1979] does not include \(r^{-1}\), but it is studied elsewhere where it is called the “converse” operator [Harel et al. 2000]. From this perspective, the main technical contribution of the present article would seem to be the treatment of error assertions. Of course, the larger contribution is conceptual, involving the relevance to proving the presence of bugs as well as connections to principles in static analysis tools, including the work in the next section. ### 6 REASONING WITH THE LOGIC In this section we investigate reasoning patterns that can be expressed with incorrectness logic. We consider examples motivated by existing tools such as DART, KLEE, CBMC and Infer, as well as ones that might lead in future to increased expressiveness or efficiency in reasoning. We stress, though, that we are not claiming at this time that incorrectness logic leads to better practical results than these mature tools; this is an exploration to give insight into the theory, and a basic test of a potential foundational formalism is how it expresses a variety of patterns that have arisen naturally. We do not include a formal treatment of procedures in this paper, but we will use the proof system in a way that lets us reason from hypotheses for parameterless procedures, as in \([p]\text{foo}()\text{[ok q][er s]} \leftarrow [p']C\text{[ok q'][er s']}\) where calls to \text{foo}() can occur within \(C\). Where we reason about the body of \text{foo}() to establish a spec, we don’t need to revisit its body at call sites. This principle of reuse is fundamental in program logics, and also in summary-based program analysis [Reps et al. 1995]. (To people with a program analysis background, when you see a presumes/achieves spec you might think: “summary”!) 6.1 Reasoning about Loops Figure 5 contains several loops, and client programs that use them. The first loop, loop0(), is a variant on an example testme_1nf of Cadar and Sen [2013], which was used there to demonstrate a loop with an indeterminate number of iterations. When we omit mention of a presumes assertion, as throughout this figure, the understanding is that it defaults to true. We have given an achieves result for loop0(). Postponing for a moment discussion of how we can actually prove this result assertion, we can use it during reasoning about client0(). Immediately after the call to loop0() on line 14 we use incorrectness logic’s rule of consequence with an implication backward from the if condition \[ \text{[true]} \text{loop0()} \text{[ok: } x >= 0 \] } \quad x >= 0 \iff x == 2,000,000 \] and we use the sequencing rule to conclude that an error is reachable, which is recorded in the achieves of client0() at line 13. But how can we obtain the spec of loop0()? It is very easy: we unwind the loop once. Here is the unrolling, with assertions at intermediate points to hint at how to construct a proof. 1 \[ x == 0 \] 2 \[ \text{if (n > 0) } 3 \quad \text{[true]} \quad x == 0 \land n > 0 \quad x = x + n; \quad n = \text{nondet}(); \quad [x > 0] 4 \) \[ \] \[ \text{else} 5 \quad \text{[true]} \quad x == 0 \land n <= 0 \quad \text{skip}; 6 \] 7 \[ \quad [x > 0] \land [(x == 0 \land n <= 0) \quad \text{assume (n <= 0)}; 8 \] \[ \] \[ \quad \text{(x > 0 \land n <= 0) } \land [x == 0 \land n <= 0)\] 9 \[ \text{[true]} \quad \text{loop0()} [ok: x >= 0] 10 \] \[ \quad [ok: x >= 0 \land n <= 0] \] The disjunction at line 9 of this proof outline contains one assertion for each branch of the if, and the assertions at lines 9 and 10 are logically equivalent; they follow the condition for loop exit at line 8. If we put this together with the first two statements in loop0(), then existentially quantify \( n \) using the local variable rule, we obtain the triple \([true]\text{loop0()} [ok: x >= 0]\) using the Unrolling Rule plus plus the Rule of Consequence to strip \( 3n \). Now, incorrectness logic tells us that \([ok: x >= 0]\) is a correct under-approximate result, but how do we know how many paths our reasoning covers? After all, we only considered one loop unrolling before reaching our conclusion. In this case, we happen to be in the lucky situation where the post-assertion is also true for over-approximation. That is, we have \[ [true]\text{loop0()} [ok: x >= 0] \quad \text{and} \quad [true]\text{loop0()} [ok: x >= 0] \] and it would not be difficult for a tool to discover an invariant \( x >= 0 \) sufficient to prove the over-approximate triple. So, the under-approximate result assertion covers all terminating paths. Cadar and Sen [2013] use this example to illustrate the challenge of needing to cover potentially infinitely many paths, and they rightly say “In practice, one needs to put a limit on the search, e.g., a timeout, or a limit on the number of paths, loop iterations, or exploration depth.” Interestingly, for this example we have shown a precise sense in which we can get a post that is as general as can be by reasoning in incorrectness logic with one loop unrolling (though we do appeal to over-approximate reasoning to confirm that this general assertion does indeed cover all paths). ```c int x; void loop0() /* (default presumes is "true" when not specified) achieves: [ok: x>=0 ] */ { int n = nondet(); x = 0; while (n > 0) { x = x+n; n = nondet(); } } void client0() /* achieves: [err: x==2,000,000 ] */ { loop0(); if (x==2,000,000) {error();} } void loop1() /* achieves1: [ok: x==0 || x==1 || x==2 || x==3 ] achieves2: [ok: x>=0] */ { x = 0; Kleene-star{ x = x+1; } } void client1() /* achieves: [err: x==2,000,000 ] */ { loop1(); if (x==2,000,000) {error();} } void loop2() /* achieves: [err: x==2,000,000 ] */ { x = 0; Kleene-star{ if (x==2,000,000) {error();} x = x+1; } } ``` Fig. 5. Iteration Examples We can’t always be so lucky as to get such a general result after one iteration. Consider loop1() in the figure, which starts with x=0 and then increments x an arbitrary number of times before exiting. We use Kleene-star( . ) instead of the ( . )* notation when showing code. There are infinitely many paths through loop1(), and the loop is not guaranteed to terminate. Using the Unrolling rule we can obtain post-conditions for any of the finite unrollings of the program. achieves1 shows the obtained result for three unrollings. While it does not cover all of the behaviours of the program, it is indeed a sound under-approximation. We can think of the pair true/achieves1 as a procedure summary for loop1(). This way of reasoning about individual paths to obtain an under-approximate assertion is related to the method of Godefroid [2007] to produce procedure summaries for the purpose of scaling symbolic execution. Next let’s consider the function client1() that calls loop1(). The assertion achieves1 is not enough to prove that an error can occur. We could boundedly unroll the loop 2,000,000 times to prove the bug in client1(), but then this unrolling would not cover a different client program where the bug happens at 4,000,000. If, however we are lucky enough to have the more general achieves: \([\text{ok}: x \geq 0]\) for \(\text{loop1}()\), then we can strengthen it using the implication \(x = 2,000,000 \implies x > 0\), as we did with \(\text{client0}()\) above, to prove the error. We can obtain the better under-approximate assertion \(x \geq 0\) for \(\text{loop1}()\) using the following instance of the Backwards Variant rule where \(p(n)\) is \(x = n\). \[ \frac{[x = n \land \text{nat}(n)]x = x + 1[\text{ok}: x = n + 1 \land \text{nat}(n)]}{[x = 0](x = x + 1) \ast [\text{ok}: \exists n. x = n \land \text{nat}(n)]} \] \(n\) fresh The premise can be derived using the assignment axiom and the rule of consequence. The use of the result assertion achieves to prove \(\text{client1}()\) is related to the use of under-approximation to obtain faster counterexamples in CBMC [Kroening et al. 2015]. The Backwards Variant rule does not describe cases where an error occurs during execution of a loop body. But, as describe before, we can use it to describe the “frontier”, the states obtained by some number of iterations before a last, erroneous, one, and then use the Iterate non-zero. For example, suppose we move the assert statement inside the loop, as in the function \(\text{loop2}()\) in Figure 5. We can prove this in two stages. First, we show \[ [x = 0](\text{Body}) \ast [\text{ok}: x = 2,000,000]. \] This can be proven using the Backwards Variant rule taking \(p(n)\) to be \(0 \leq x \leq 2,000,000 \& \& x = n\). We then use the rule of consequence to shrink the post-assertion, giving \[ [x = 0](\text{Body}) \ast [\text{ok}: x = 2,000,000]. \] Next, the assert rule plus the short-circuiting rule for Sequencing give us \[ [x = 2,000,000] \text{Body}[\text{er}: x = 2,000,000]. \] These specs line up for sequential composition, to give us \[ [x = 0](\text{Body}) \ast \text{Body}[\text{er}: x = 2,000,000] \] and then Iterate non-zero yields \[ [x = 0](\text{Body}) \ast [\text{er}: x = 2,000,000]. \] This proves \(\text{loop2}()\) from Figure 5. Reasoning with loop variants sometimes allows more compact and general under-approximate assertions to be derived than would be obtained by taking posts for each of many individual paths. ### 6.2 Conditionals, Expressiveness and Pruning Conditional statements cause challenges for reasoning tools. The use of Boolean conditions that are difficult for current theorem provers to deal with causes expressiveness issues, and the number of paths that can occur through the code, even without loops or recursion, can lead to inefficiency. **Conditions that are Difficult for Symbolic Reasoning.** Consider the code for \(\text{client}()\) in Figure 6. The function \(\text{difficult}()\) is assumed to be difficult for a reasoning tool to treat precisely. Cadar and Sen [Cadar and Sen 2013] present an example using multiplication, which goes beyond the decidable subsets of arithmetic encoded in automatic theorem provers. Other examples might be hash functions, unknown or binary code, or code that is obfuscated in a way that purposely makes automated analysis difficult. How can we obtain a correct under-approximate post? Dynamic symbolic execution, as represented by DART, EXE, and KLEE [Cadar and Sen 2013], takes a particularly pragmatic approach based on the principle: when symbolic reasoning is difficult, replace a symbolic variable with a concrete value. In the example above, let’s consider replacing \(x\) by the number 7. By this tack, we can obtain achieves1: \([y = 49 \& \& x = 1]\), and we do this by shrinking the post-assertion. That is, the assume statement corresponding to the true branch ```c int x, y; int difficult(int y) { return (y*y); /* or, return hash(y) ... or, unknown code */ } void client() { /* achieves1 : [ok: y==49 && x==1] */ achieves2: [ok: exists z. (y==difficult(z)& x==1)||(y!=difficult(z)& x==2)] achieves3: [ok: x==1 || x==2] /* { int z = nondet(); if (y == difficult(z)) { x=1; } else { x=2; } } */ { client(); if (x==1 || x==2) { error(); } } } void test1() { /* achieves2 : [ok: exists z. (y==difficult(z)& x==1)||(y!=difficult(z)& x==2)] */ { client(); if (x==1 || x==2) { error(); } } } void test2() { /* achieves3 : [ok: x==1 || x==2] */ { client(); if (x==2) { error(); } } } ``` Fig. 6. Conditional Examples of the if statement is \(y==\text{difficult}(z)\) with post-assertion \(y==z*z\), and we have an implication \(y == z * z \iff y == z * z \land z == 7\) so using the incorrectness logic consequence rule we obtain a post with \(y == 49\). Thus, the logical principle of \textit{shrinking the post} gives us sound triples corresponding to the pragmatic analyzer principle of \textit{concretizing symbolic values}. Another sound approach to difficult-to-reason-about Booleans is to record information lazily, in the post-assertion, in the hopes that the code might be used in contexts where the difficulty is immaterial. achieves2 on line 47 does this, and can be used in test1() to prove an error. A final approach is to record disjuncts for both branches while discarding the difficult bits, as in achieves3. This is unsound: we need to keep information correlating \(y\) with \(x\) as, e.g., the final state \((x \mapsto 1, y \mapsto 3)\) is not reachable but satisfies \(x==1 || x==2\). Further, if we use achieves3 when reasoning about test2, then we would wrongly conclude that there could be an error. Though unsound, this approach has been used for pragmatic reasons in SMART [Godefroid 2007], descendant of DART and a precursor of SAGE [Godefroid et al. 2008] at Microsoft, and in Infer.RacerD, a data race detector in production at Facebook [Blackshear et al. 2018]. SMART trips a flag indicating this unsoundness when it occurs, and then uses procedure summaries that no longer under-approximate when generating further test cases. Overall soundness is rescued by appeal to concrete execution. RacerD on the other hand adjusts its soundness claim [Gorogiannis et al. 2019]: it is an under-approximation of an over-approximation, where the over-approximation arises by replacing Booleans it doesn’t understand with nondeterministic choice. So the reasoning is sound when \textbf{if} is replaced by +. It seems as if the same under-of-over approach could be taken theoretically to prove an additional result about SMART’s summaries. So, an unsound choice, achieves3, is not unreasonable. Localized unsound decisions might be made by a tool, which represent assumptions that can be used as input to further sound steps which are justified by logic. From this perspective, the role of logic is not to produce iron-clad unconditional guarantees, but is to clarify assumptions and their role when making sound inferences. **Dropping disjuncts.** We have described earlier how removing a disjunct is a sound step in incorrectness logic. Infer.Pulse takes the blunt approach of having two limits, the number of loop unrollings and the number of disjunctions; it simply drops disjuncts when they exceed the limit. Jules Villard communicated a recent example of running Pulse on a C++ codebase inside Facebook with 100s of thousands of lines, comparing a 20 disjunct limit against 50 disjuncts; in both cases with the unrolling limit was set to 5. The result was that the 20 disjuncts case was $\sim 2.75x$ wall clock time faster, $\sim 3.1x$ user time faster, and it found 97% of the issues that the 50 disjuncts case found. The point is that engineering and not only philosophical considerations are relevant to the question of when it is worth the energy cost, computer time or human time to address the other 3%. The choice is not a binary one between fast and slow; e.g., we might deploy them at different times, the fast as part of code review and the slow later in the software development process (and run less frequently). The specific numbers such as $\sim 2.75x$ are not important, and we caution the reader not to read too much into them. But, the method of dropping disjuncts should not be dismissed as unprincipled; it gives engineers a knob to turn when considering how and when to deploy a tool. While setting a limit can be useful, sometimes one can manage to always keep exactly one disjunct, obtained in a smarter way than by pruning. Our looping examples earlier did this for specific programs, by manually-provided assertions that cover infinitely many paths. Automatic reasoning in over-approximate tools often aim for a join operator that produces a single state over-approximates a disjunction. The Infer.RacerD data race detector [Blackshear et al. 2018] has an example for under-approximate joining. RacerD assumes that the code it runs on will mostly use locking and unlocking in a bracketed way. It exploits this by keeping track of the number of times a (re-entrant) lock has been locked, and then taking the maximum of lock counts at join points (e.g., at the end of conditionals). This decision leads to false negatives, missing bugs when code of the form `maybe_lock; write(x)` can race with `lock; read-or-write(x)`, but it does not lead to false positives. An example like this is in Figure 7. There, the achieves of `maxing()` is such that reasoning with it will not reveal the error in `false_negative()`, but it is sufficient to find the error in `true_positive()`. We can obtain the achieves assertion instead of `[locked==0 || locked==1]` using the typical incorrectness logic reasoning that shrinks the result assertion. Aside: While the ability to drop disjuncts allows one of the practical difficulties of over-approximate reasoning – the need to cover all paths – to be avoided, one might wonder whether the converse inability to drop conjuncts when reasoning along a path might lead to practical difficulties. This is a legitimate question, but there are a number of remediations. First, localization via the Constancy and Local Variable rules lets us limit the information in the post. This is (implicitly) used in SMART, where under-approximate summaries are represented concisely by tracking modified values without explicitly writing the full post. Second, one can consider doing under-approximation after an over-approximation step, as in RacerD and Infer.Pulse. Over lets you ignore values, and then reason under, leading to underapproximate-modulo-assumptions. The theoretical restriction on dropping information along a path is not an ultimate blocker for under-approximate reasoning. ### 6.3 Symbolic Reasoning and Flaky Tests A “flaky test” is one that, due to nondeterminism, can give different answers on different test runs. Conversely, we call a test “sturdy” if gives the same answer on all runs of a program. Flakiness ```c int locked; void maxing() /* achieves: [ok: locked==1] */ { int z=nondet(); if (z) { locked=0; } else { locked=1; } } void false_negative() /* achieves: [er: false] and [ok: locked==1] */ { maxing(); if (locked==0) { error(); } } void true_positive() /* achieves: [er: locked==0] */ { maxing(); if (locked>0) { locked=locked-1;}; if (locked==0) { error(); } } ``` Fig. 7. Maxing Out ```c void foo() /* sturdy presumes [x is even] , sturdy achieves [er: x is even],[ok: false] flaky presumes [x is odd] , flaky achieves [er: x is odd],[ok: x is odd] */ { if (x is even) { error();} else { if (nondet()) { skip;} else {error();} } void flaky_client() /* flaky achieves: [er: x==3 || x==5] */ { x = 3; foo(); x = x+2; assert(x==4); } ``` Fig. 8. Sturdy and Flaky is increasingly considered to be a problem in deployments of testing in industry [Harman and O’Hearn 2018]. We develop an example illustrating a logical account of sturdy and flaky tests. We are going to use classic notions from backwards reasoning. If $\pi$ is a path in a program, then - $wp(\pi)q$ describes states for which execution of $\pi$ is guaranteed to terminate and satisfy $q$; - $wpp(\pi)q$ describes states for which execution of $\pi$ is possible to terminate and satisfy $q$. $wp$ is Dijkstra’s weakest pre-condition [Dijkstra 1976]. $wpp$ is the weakest possible pre-condition, a predicate transformer described by Hoare [1978] for what he referred to as “possible correctness”. (Note: $wp$ cannot be defined using the relational model of this paper.) We will use these ideas to obtain pre-assertions, followed by forwards reasoning to obtain under-approximate post-assertions. Procedure foo() in Figure 8 contains three paths, and $wp(\text{assume x is even})true$ for the path prefix of the first of them gives us an input condition which forces execution to reach error() on line... 4. We install this as the (sturdy) presumes. Forward reasoning obtains this as the under-approximate error post as well. The sturdy presumes assertion catches one bug but misses two others: the second error() statement at line 5 in foo(), and the assert at line 14 in flaky_client(). The other two paths in in Figure 8 end in skip and error(), and each has a prefix \( \pi \) equivalent to assume(x is odd); b = nondet(); assume b for a variable b considered local to the trace. wp(\( \pi \))true is false, indicating that there is no input state which can force execution down either path. So, we appeal to the weakest possible pre-condition, which describes the pre-states that can possibly lead to the post, and we find that wpp(\( \pi \))true = x is odd. We install this as what we label the flaky pre, and forwards reasoning then gives us the two achieves assertions. The flaky error assertion reveals the potential bug of the second error() in foo(), and the ok assertion is used in flaky_client() to reveal that the assert statement can fail. Note that even though we started reasoning backwards from true, we did not keep true as the achieves assertion (the post). The reason is that true is not a sound under-approximate post. The effect of this could be seen if we replaced the statement assert(x==4) by assert(x==5) and simultaneously the flaky achieves [ok: x is odd] with [ok: true]. Then, we would wrongly conclude that assert(x==5) in the altered flaky_client() could fail. When we use backwards reasoning to generate a pre starting from a given post, we need also to be careful to update that post if we are to re-use the reasoning in other contexts. Test runs starting from inputs satisfying the flaky presumes are not reproducible, unless our testing engine were to record all nondeterministic choices; an expensive matter for a testing tool. From a logical point of view there is an interesting possibility: even if we have nondeterminism at runtime, a proof of incorrectness can be checked again and again in a deterministic fashion. We wonder whether symbolic proofs of bugs might help with the practical problem of flaky tests. 6.4 Composition and Procedural Abstraction This section discusses reasoning that chains several procedure calls together. If we have a path without procedure calls – say a sequential composition of assignment, assume and assert statements – then we can perform strongest post-condition reasoning, which is also therefore under-approximate. Collecting together such pre/post pairs for a number of paths can allow us to form an under-approximate summary for a procedure. But then reasoning with a path containing a procedure call should use these summaries, and there is subtlety in doing so soundly. We illustrate with the specs in Figure 9. \( x>0 \) is the strongest post of \( x=x+1 \) given \( x>=0 \), and so is therefore under-approximate too. Let’s try to reason about the sequential composition in client() using \( \text{presumes1/achieves1} \) from line 2. In Hoare logic we could do this with the rule of Consequence and \( x > 0 \Rightarrow x >= 0 \), giving \( \{x>=0\text{inc()}\text{; inc()}\{x > 0 \} \). The post here is a correct over-approximation, but it is not the strongest post of the sequential composition, and it is not a correct under-approximation. If we were to use this wrong achieves 1 at line 9 while reasoning about test() then we would wrongly conclude that an error is possible. What is happening here is that there is a discrepancy between the strongest post-condition of the code for inc();inc() and what can be inferred from the specs, even though achieves1 at line 2 is the strongest post of a single call. That is, wrong achieves1 is the strongest post for the composition \( r;r \) for greatest relation \( r \) satisfying \( \{i>=0\}r\{x > 0 \} \), but it is not for \( x=x+1 \): the greatest relation, what we know from the spec, does not under-approximate the code for inc(). The moral of this story is that when proving that bugs can occur we need to be careful about what strongest post-condition reasoning gives us in the presence of procedures. Incorrectness logic provides this care. When faced with the above scenario, it tells us not to make the problematic inference, that we should insist instead on an implication in the reverse direction. That is, we ask for \( x > 0 \iff x >= 0 \) and when we see it is false, we block reasoning about the sequential composition. So, incorrectness logic prevents the unsound (for bug catching) inference. Furthermore, it shows that we need a different spec to draw useful conclusions about the composition. A different spec of inc(), given by presumes2/achieves2 on line 3, lets us reason about the composition inc();inc() in client() more positively, to obtain presumes2/achieves2 as stated for client() on line 10. The reasoning leading to these specs uses the rules of Substitution and Constancy from Figure 3. Note that to apply these rules, a procedure spec or summary should carry information about free variables and modified – here, that x is both free and modified, and that m is not free in the procedure body (m functions as a “logical variable” or a “ghost variable”). An instance of Substitution I, substituting m + 1 for m, is \[ \begin{align*} [i == m & m > 0] & \text{inc}() [ok: i == m + 1 & m > 0] \\ [i == m + 1 & m + 1 > 0] & \text{inc}() [ok: i == m + 1 + 1 & m + 1 > 0] \end{align*} \] Next, we apply Constancy using m > 0 as the invariant, to give us \[ \begin{align*} [i == m + 1 & m + 1 > 0 & m > 0] & \text{inc}() [ok: i == m + 1 + 1 & m + 1 > 0 & m > 0] \end{align*} \] and this is equivalent to \[ \begin{align*} [i == m + 1 & m > 0] & \text{inc}() [ok: i == m + 2 & m > 0] \end{align*} \] Now we have a triple for inc() whose pre exactly matches the given achieves2 for inc() on line 3 in Figure 9, and we can use the sequencing rule to infer i == m + 2 & m > 0 as the result assertion for inc();inc() and the achieves2 for client() at line 10. When reasoning about test() using this spec we will not wrongly trip the assertion at line 20 because the Boolean condition x>=2 does not imply the post-assertion false for the call to client() at line 19. There is a general pattern to this reasoning. Let's say that a symbolic state is of the form \[ x_1 == m_1 & \cdots & x_k == m_k \land F \] where the m_i are “logical variables”, variables that do not occur in any program, and F is expressed in terms of logical variables only. We can make the pre-assertion of one procedure imply the Fig. 9. Specs for Composition post-notification of another by using the Substitution I together with conjoining the $F$ parts using Constancy. Patterns of this form could be taken advantage of in automated tools. Finally, the reader might have recognized a lack of generality of the specs given in examples previously, e.g., for the loops in Figure 5. There, we used $true$ for the (default) presumes assertions, and this prevents reasoning about programs that chain several calls together. If we try to reason about $\text{client1(); client1()}$ then because the pre of the second call does not imply the post of the first we have a problem. The reader might enjoy adjusting the specs to allow such reasoning. 7 CONTEXT The ideas leading to this paper have been stewing for some time. Since the Infer tool was deployed at Facebook in 2014 it has seen over 100,000 reported issues fixed by developers before reaching production [Distefano et al. 2019]. This impact is based on two factors. First, Infer uses a compositional algorithm that is crucial to its deployment on a rapidly changing codebase with tens of millions of lines. Second, it is used to find regressions on code modifications as part of the code review process. The theory Infer was based on originally [Calcagno et al. 2011] gave rise to the compositional algorithm, but was formulated as a correctness theory that does not match its use to find bugs rather than to prove their absence. This mismatch led to a focus on under-approximation in the design of the RacerD program analyzer in work with Sam Blackshear, Nikos Gorogiannis and Ilya Sergey [Blackshear et al. 2018], an idealized version of which enjoyed a “no false positives theorem” [Gorogiannis et al. 2019]. By this point the author was becoming convinced that, perhaps contrary to prevailing opinion, design decisions favouring reduction of false positives over false negatives could be taken in a principled way, not based only on heuristics such as alarm filtering. These considerations led to the decision to base a new analyzer – Pulse, developed principally by Jules Villard – on the idea: “what if we go back to the original design of Infer, but take bug-catching instead of proving absence as the aim?”. Discussions between Jules and the author led to design decisions that were incompatible with the over-approximate theory of the original Infer: - bound loops to escape the quagmire of over-approximating loops (i.e., depending on “magical” abstract domains that do not yet and may never exist, e.g., for memory properties); - be disjunctive to enable precision, but prune disjuncts to maintain scalability. Yes, it would be wonderful to have the magical abstract domains capable of automatically proving absence of all bugs in large codebases (e.g., linux, the 100s of millions of LOC at Facebook [Distefano et al. 2019], the billions of LOC at Google [Potvin and Levenberg 2016]), while also keeping up with the rapid pace of change of such codebases. No such domains have been demonstrated as of yet, so bug catching remains important. Next, in a discussion in Lisbon at POPL’19, Derek Dreyer and Ralf Jung suggested that the aims of Pulse might be understood in terms of a logic for proving presence of faults. At that time Derek coined the term “incorrectness logic”. They proposed a model of triples with finding faults in mind, but it turned out not to fit with Pulse (e.g., it did not allow dropping disjuncts). Then, based on my extended ruminations on under-approximation, I discovered the under-approximate triples, and was surprised to find a smooth proof theory for them. It was clear that the ideas were much more general than the specific analysis problems that prompted them and I decided to try to develop the simplest version of the theory I could think. I toyed with the name “under-approximation logic”, but Derek’s term “incorrectness logic” has a nice ring so I used it (with his permission). After completing the work in the paper, but fortunately before publication, I learned of the paper of de Vries and Koutavas [2011] on reverse Hoare logic (thanks to Emanuele D’Osualdo for pointing this out). They include a proof system and completeness theorem for normal termination for what I call under-approximate triples, and I was amazed to see that they had almost the same rules for triples with \( ok \) conclusions. This coincidence suggests that the rules are natural or perhaps even inevitable. They do not include error specs or make the connection to proving the presence of bugs, the main topic of the present paper. But, I acknowledge the priority of de Vries and Koutavas in their discovery of the under-approximate triple. I also acknowledge that many if not all the rules for triples with \( ok \) post-assertions can be obtained via compilation into dynamic logic; see Section 5.3. There has been important related research on test-case generation by symbolic execution, as in the pioneering work of King [1976]. This whole area (see Cadar and Sen [2013] for a survey) provided inspiration for the current article. We were particularly motivated by compositional methods for symbolic execution [Godefroid 2007], which shows cases where under-approximate summaries can be computed in a way that helps the reasoning to scale to larger programs. The concept of necessary precondition [Cousot et al. 2013] is related. A necessary precondition for a program is a predicate which, whenever falsified, leads to divergence or an error, but never to successful termination. If \( p \) is a necessary pre-condition, then \( \neg p \) need not be a presumption which leads to an error in incorrectness logic, because the possibility of divergence from a necessary pre-condition leads to false positives. Additionally, when [presumption] \( C[er: \text{result}] \) holds it can be that \( C \) delivers successful states as well as erroneous ones when starting from the presumption. Finally, there are programs for which no non-trivial necessary pre-condition exists (e.g., \( \text{skip + error()} \)), but where perfectly fine presumptions exist for incorrectness logic. Another related work is on the Thresher tool [Blackshear et al. 2013], which includes a proof system for refuting spurious counterexamples. They have a reversed rule of consequence but their post-assertions do not under-approximate, allowing for unreachable states. Where our triple is defined by under-approximating the strongest postcondition, theirs can be thought of as over-approximating the weakest possible precondition \( wpp(C)q \), which describes the states that can possibly lead to \( q \) (i.e., \( \langle C \rangle q \) in dynamic logic). Thresher makes use of the capability of enlarging the pre-assertion, by dropping conjuncts in a bid to over-approximate a loop going backwards, and it may be that such a facility could prove useful for incorrectness logic as well. Another backwards transformer, the weakest liberal precondition \( wlp(C)q \) (‘liberal’ allowing for divergence), can be used to characterize Hoare’s triple: \( p \subseteq wlp(C)q \) and \( post(C)p \subseteq q \) give equivalent characterizations of \( \langle p \rangle C\langle q \rangle \). Curiously, flipping the subset relation gives two inequivalent notions, \( p \supseteq wlp(C)q \) and \( post(C)p \supseteq q \). Replacing \( wlp \) with the weakest possible precondition \( wpp(C)q \) leads to a relationship \( p \supseteq wpp(C)q \) which is as in Thresher and in necessary preconditions, the difference being that in Thresher \( q \) describes error states where Cousot et al. [2013] use \( q \) to describe success states. I am grateful to Benno Stein for discussions on Thresher, necessary preconditions, and \( wpp \). 8 CONCLUSION AND OPEN PROBLEMS Techniques for reasoning about program correctness have been extensively developed. Turing [1949], used logical assertions to reason about a particular program. and in the 1960s Floyd [1967] and Hoare [1969] created systematic methods for reasoning about classes of programs. In all these cases the assertions were arranged to over-approximate the reachable program states. Further developments in verification, including temporal logic [Pnueli 1981] and separation logic [O’Hearn 2019; Reynolds 2002], have expanded the techniques available for proving absence of errors. In this paper we have suggested that reasoning about program incorrectness (or, the presence of bugs) can be placed on a logical footing, related to but different from the well developed foundations for showing correctness (or, the absence of bugs). Each form of reasoning is as fundamental as the other, they just have different principles, as illustrated by the following fundamental duality which has been highlighted in the paper. For correctness reasoning, you get to forget information as you go along a path, but you must remember all the paths. For incorrectness reasoning, you must remember information as you go along a path, but you get to forget some of the paths. In the paper we: (1) described how the under-approximate triple is relevant to proving the presence of bugs, and why assertions covering successful termination are needed even if our concern is with errors; (2) designed a specific logic, which we called incorrectness logic, along with a semantics and proof theory; (3) explored reasoning idioms, including making connections to concerns in automatic program analysis. We have tried to argue and show via the examples that the principles exposed in (1) and (2) are germane to the problem of proving the presence of bugs. There are many problems for further work, including the following. **Other Models.** There are models worth exploring other than where states denote functions from variable to values and where commands denote relations. Particularly important are models taking into account executions and not only initial and final states. The model in this paper describes existence of executions leading to errors, but not the traces themselves. An interesting proposal in this direction has been made by Hoare (see, e.g., [Hoare et al. 2011]). He describes an approach to over-approximating triples, where $[p]c[q]$ is interpreted as $q \supseteq p; c$, and it makes sense as well to interpret the under-approximate triple $[p]c[q]$ as $q \subseteq p; c$. In Section 5.3 we considered such an interpretation when $p$, $c$ and $q$ denote relations, but Hoare envisages a wider range of models, including ones where they denote sets of traces. The Hoare triple can be read as saying that $q$ over-approximates the composition of program $c$ with an assertion describing traces up to the point before the program starts. Likewise, it would be appealing to consider a traces model of incorrectness logic and show that it forms a useful basis for (especially, automatic) reasoning. The conceptual appeal of a traces model is possibly even stronger for under-approximating than over-approximating logic: the traces would show actual executions, leading to actual bugs. In order to reason about pointer manipulation, one might consider an under-approximate version of separation logic. This extension is not at all trivial, as the standard heap model of separation logic does not mesh well with under-approximation (separation logic’s frame rule can become unsound), but in work with colleagues at MPI-SWS and Facebook we have shown that local reasoning based on the frame rule can be preserved in an alternate model; investigations continue. **Concurrency.** Correctness logics for concurrency attempt to go beyond the method of enumerating interleavings to obtain more efficient means of program proof [Brookes and O’Hearn 2016; Hayes and Jones 2017]. Techniques that they use (e.g., resource invariants) were designed with over-approximation in mind, and do not immediately carry over to under-approximation. RacerD [Blackshear et al. 2018; Gorogiannis et al. 2019] gives one pragmatic example of what a concurrency logic for under-approximation might seek to cover or explain. **Compositional and Incremental Static Bug Catching.** The theory of summary-based and compositional program analysis has assumed over-approximation [Calcagno et al. 2011; Cousot and Cousot 2001; Reps et al. 1995]. But, often, tools whose architecture resembles that prescribed by theory are deployed as bug catchers [Blackshear et al. 2018; Bush et al. 2000; Distefano et al. 2019; McPeak et al. 2013]. Some tools borrow ideas from interprocedural static analysis, but fall back on concrete execution for their soundness [Godefroid 2007]. It would be worthwhile to adapt the analysis that led to Facebook Infer [Calcagno et al. 2011], and the recent bounded version [Santos et al. 2019], to refer to under-approximation. Pulse is one attempt in this direction. In addition to providing a foundation for further development of static and mixed static/dynamic bug catchers, it is hoped that theory can help expand the effectiveness of such tools. **Termination Proving.** The under-approximate triple \([p]c[q]\) does not guarantee termination on all inputs, but nevertheless guarantees existence of some terminating paths. A variety of techniques have been developed for automatically inferring loop variants and other forms of termination argument [Cook et al. 2011]. We speculate that such techniques might be brought to bear on automatic reasoning about incorrectness, both to accelerate reasoning techniques within one procedure and to infer more general summaries for under-approximate inter-procedural analysis. **Abstract Interpretation.** Abstract interpretation is a general theory of semantics which can in principle be used to describe under-approximation as well as over [Cousot and Cousot 1977]. There have been papers on under-approximation (e.g., [Ranzato 2013; Rival 2005; Schmidt 2007]), but the vast majority of work has concentrated on over-approximation. We hope that incorrectness logic can be neatly characterized in abstract interpretation terms, perhaps adapting the account for over-approximate logics of Cousot [2002]. More generally, we expect that abstract interpretation can eventually play a guiding and explanatory role for a wide range of static and dynamic under-approximate tools for bug catching, similar to what it already does for over-approximate analyses. **Testing.** We described the relationship with testing at a high level in the discussion of the Principle of Denial in Section 2. We wonder whether logic might be used to make testing faster, perhaps in a similar way to how symbolic model checking achieved striking gains over explicit state [Burch et al. 1992]. Another avenue to explore is to attack the problem of flaky tests using logic. Generally, it seems that there is much more that can be done to exploit logic in program testing. In summary, there is a rich variety of problems for both experimental and theoretical work to bring the foundations of reasoning about program incorrectness onto a par with the extensively developed foundations for correctness. ACKNOWLEDGMENTS I’m sure that I would never have developed incorrectness logic were it not for the experience of moving from academia to Facebook engineering [Constine 2013]: trying to deploy reasoning to production forced me to grapple with problems I otherwise wouldn’t have encountered. I’m indebted both to my teammates on the Infer team and to the engineers in the product teams we serve for teaching me so much about applying reasoning tools in real world. Special thanks to Mark Harman and Tony Hoare for discussions on the specific content and the broader picture for this work. Finally, thanks to all the colleagues mentioned in Section 8 for discussions that influenced my thinking. REFERENCES
Effective polyploidy causes phenotypic delay and influences bacterial evolvability Lei Sun†‡, Helen K. Alexander‡*, Balazs Bogos1, Daniel J. Kiviet2,3, Martin Ackermann2,3, Sebastian Bonhoeffer1* 1 Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland, 2 Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zürich, Switzerland, 3 Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland ‡ These authors share first authorship on this work. * seb@env.ethz.ch Abstract Whether mutations in bacteria exhibit a noticeable delay before expressing their corresponding mutant phenotype was discussed intensively in the 1940s to 1950s, but the discussion eventually waned for lack of supportive evidence and perceived incompatibility with observed mutant distributions in fluctuation tests. Phenotypic delay in bacteria is widely assumed to be negligible, despite the lack of direct evidence. Here, we revisited the question using recombineering to introduce antibiotic resistance mutations into E. coli at defined time points and then tracking expression of the corresponding mutant phenotype over time. Contrary to previous assumptions, we found a substantial median phenotypic delay of three to four generations. We provided evidence that the primary source of this delay is multifork replication causing cells to be effectively polyploid, whereby wild-type gene copies transiently mask the phenotype of recessive mutant gene copies in the same cell. Using modeling and simulation methods, we explored the consequences of effective polyploidy for mutation rate estimation by fluctuation tests and sequencing-based methods. For recessive mutations, despite the substantial phenotypic delay, the per-copy or per-genome mutation rate is accurately estimated. However, the per-cell rate cannot be estimated by existing methods. Finally, with a mathematical model, we showed that effective polyploidy increases the frequency of costly recessive mutations in the standing genetic variation (SGV), and thus their potential contribution to evolutionary adaptation, while drastically reducing the chance that de novo recessive mutations can rescue populations facing a harsh environmental change such as antibiotic treatment. Overall, we have identified phenotypic delay and effective polyploidy as previously overlooked but essential components in bacterial evolvability, including antibiotic resistance evolution. Author summary What is the time delay between the occurrence of a genetic mutation in a bacterial cell and manifestation of its phenotypic effect? We show that antibiotic resistance mutations in *Escherichia coli* show a remarkably long phenotypic delay of three to four bacterial generations. The primary underlying mechanism of this delay is effective polyploidy. If a mutation arises on one of the multiple chromosomes in a polyploid cell, the presence of nonmutated, wild-type gene copies on other chromosomes may mask the phenotype of the mutation. We show here that mutation rate estimation needs to consider polyploidy, which influences the potential for bacterial adaptation. The fact that a new mutation may become useful only in the “great-great-grandchildren” suggests that preexisting mutations are more important for surviving sudden environmental catastrophes. **Introduction** As genetic mutations appear on the DNA, their effects must first transcend the RNA and protein levels before resulting in an altered phenotype. This so-called “phenotypic delay” in the expression of new mutations could have major implications for evolutionary adaptation, particularly if selection pressures change on a timescale that is short relative to this delay, as may be the case for selection by antibiotics. The duration of phenotypic delay is an old but nearly forgotten question in microbiology[1–3]. Luria and Delbrück were interested in the delay because they expected it to affect the mutant distribution in the fluctuation test in their seminal work on the random nature of mutations [1]. They argued that if a mutant clone expressed its phenotype after $G$ generations, then phenotypic mutants should be observed in populations in groups of $2^G$. Frequent observations of single-mutant populations, however, suggested $G \approx 0$. They therefore concluded that the phenotypic delay is negligible [1,3,4]. This has remained the modus operandi [4], despite the fact that molecular cloning protocols imply a significant delay because they require a waiting time typically longer than a bacterial generation to express new genetic constructs [5]. To quantify the phenotypic delay more directly, the time point of occurrence of a mutation in a cell needs to be known, which has only become possible with modern methods of genetic engineering. Here, we use a recombineering approach to introduce mutations in *E. coli* within a narrow time window and find a remarkable phenotypic delay of three to four generations for three antibiotic resistance mutations. We identify the underlying mechanism as effective polyploidy, which reconciles the long phenotypic delay with Luria and Delbrück’s observations. Investigating the consequences of effective polyploidy and phenotypic delay, we find that mutation rate estimates need to be adjusted for ploidy. Moreover, resistance mutations that occur after exposure to antibiotics are much less likely to survive due to the multigenerational phenotypic delay, while preexisting mutations become a much more important contributor to survival. **Results** **Mutations in bacteria exhibit multigenerational phenotypic delay** To quantify phenotypic delay, we introduced each of four mutations at a specified time point in *E. coli* with an optimized recombineering protocol (Materials and methods), in which a single-stranded DNA (ssDNA) oligonucleotide carrying the point-specific mutation is transformed into bacteria by electroporation [6]. The ssDNA then binds reverse complementarily to its target on the bacterial genome as part of a lagging strand in an open replication fork [6], thereby introducing the mutation. Three mutations confer antibiotic resistance to rifampicin, nalidixic acid and streptomycin, respectively (RifR, NalR, and StrepR) [7]; the fourth mutation enables lactose prototrophy (lac+ [8] (S1 Table). After introduction of the mutations, the cells grew continuously without selection and were sampled over time. Sampled cells were subjected to “immediate” versus “postponed” selection to quantify, respectively, the frequencies of current phenotypic mutants and of genotypic mutants (that contain at least one mutant gene copy and eventually have some phenotypic mutant descendants), with their ratio called phenotypic penetrance (Fig 1). Phenotypic delay is quantified as the time in bacterial generations to reach 50% phenotypic penetrance. Surprisingly, all three resistance mutations showed significant phenotypic delay at two selective concentrations of their respective antibiotic (Fig 2A). Reaching 50% phenotypic penetrance required five to six generations of postrecombineering growth. The frequency of genotypic mutants increased over the first one to two generations but eventually declined (Fig 2C). The transient increase may reflect the time window of introduction of the mutations. Discounting the first two generations, a phenotypic delay of three to four generations remains to be explained. **Effective polyploidy is the primary source of phenotypic delay** Phenotypic delay could result from multiple factors. Firstly, it could arise from the gradual replacement of wild-type proteins by mutant proteins following mutagenesis. Time may be required for sufficient protein turnover before the mutant phenotype can manifest. Another possibility is that cells are effectively polyploid due to multifork replication [9,10]. Recombineering incorporates the mutation into only one or some of the chromosomes starting from a single-strand mutant DNA [6], comparable to the occurrence of natural mutations. This yields effectively heterozygous cells that could produce both wild-type and mutant proteins from different chromosomes, which may prevent the onset of the mutant phenotype. Three generations could be the minimal time needed for a cell with one mutant copy out of eight chromosomes (comparable to previous estimates [9]) to produce the first homozygous mutant carrying only mutant alleles. Effective polyploidy is also compatible with the observed decline in genotypic mutant frequency (Fig 2C) because heterozygous mutants produce both mutant and wild-type descendants, such that the frequency of cells carrying at least one mutant gene copy will decline until all cells are homozygous. To quantify the contribution of effective polyploidy, we used a lacZ reporter assay to visualize heterozygous mutants. We constructed three reporter strains with a disrupted lacZ gene inserted close to each resistance target gene and restored it through recombineering. Fig 2. Phenotypic delay in E. coli. (A) Phenotypic penetrance (mean ± SE; n = 6) over time for three antibiotic resistance mutations. Gray dashed lines: time at 50% penetrance. (B) Frequency of homozygous mutants among all mutants (orange) for the three resistance mutations assessed by lacZ reporter constructs (rpoB-lacZ, gyrA-lacZ, rpsL-lacZ), overlaid with their respective penetrance. (C) Genotypic mutant frequency for the resistance mutations. (D) Phenotypic penetrance of the lactose prototrophy (rpsL-lacZ). (E) Colonies founded by homozygous (blue) and heterozygous (sectored) lac+ mutants. The numerical data for panels A to D can be found in S1 Data. MIC, minimum inhibitory concentration. https://doi.org/10.1371/journal.pbio.2004644.g002 Genotypic mutants were visualized by plating on indicator media where lac⁺ and lac⁻ cells become blue and white, respectively. Heterozygous mutants generate sectored colonies, while homozygous mutants generate blue colonies, thus indicating the frequency of homozygous mutants amongst all genotypic mutants (Fig 2E). Comparing the estimated proportion of homozygous reporter mutants with the corresponding phenotypic penetrance of the resistance mutation reveals that phenotypic delay can be fully explained by effective polyploidy for NalR at 2x minimum inhibitory concentration (MIC) and for RifR (Fig 2B). Homozygosity precedes phenotypic penetrance by about 0.5 generations for NalR at 8x MIC and one generation for StrepR, suggesting that here, additional protein turnover may be involved. These results also imply that these resistance mutations are genetically recessive to antibiotic sensitivity, which has also been described in previous studies based on co-expression assays [11,12]. The recessive nature of these antibiotic resistance alleles stems from their molecular mechanism: when the antibiotic molecule binds to its target protein, the resulting complex is capable of damaging the cell even in small quantities, essentially acting as toxins. As a result, the gene dosage of wild-type targets is critical. For instance, nalidixic acid-bound gyrase proteins can introduce DNA double-stranded breaks [13]. In particular, bacteria that overexpress gyrase become even more sensitive to quinolone antibiotics [14]. Although the exact killing mechanism of streptomycin remains a subject of debate, it is generally accepted that streptomycin-bound ribosomes damage the cell via mistranslation [15]. Finally, rifampicin-bound RNA polymerase appears to blockade the DNA, thereby preventing transcription even by drug-resistant RNA polymerases [12]. Although dominant RifR mutations have also been described [16], the mutation we tested here appears to be recessive. In the case of lacZ mutations, we scored the frequency of lac⁺ phenotypic mutants on lactose-limited media. The ability to metabolize lactose is dominant to its inability [8]. Because any cell containing a lac⁺ allele can metabolize lactose and eventually form a colony, phenotypic penetrance, as expected, was always at 100% (Fig 2D), indicating that the observed phenotypic delay of resistance mutations is not an artifact of our protocol. **Effective polyploidy causes asymmetrical inheritance of mutations** A further testable prediction of effective polyploidy is that inheritance of mutant alleles is asymmetrical: heterozygous mutations are expected to produce both wild-type and mutant offspring. For mutations with intermediate dominance, offspring progressing towards mutant homozygosity should show an increasingly mutant phenotype, while others show a transient phenotype because they inherit no mutant genes and their mutant proteins are diluted over subsequent divisions. Phenotypic delay would manifest as the time such mutations need to reach full phenotypic expression. To test this prediction, we repaired a disrupted YFP gene with recombineering, creating fluorescent mutants where the fluorescence intensity depends on the number of functional copies of this gene. We then tracked fluorescence as an intermediate-dominant phenotypic trait using single-cell imaging. As expected, we observed fully, transiently, and non-fluorescent offspring lineages from recombineering-treated cells (Fig 3A–3C, S1 Movie), consistent with effective polyploidy. Furthermore, fluorescence in mutant lineages increased monotonically and reached maximal intensity almost two generations after forming homozygous mutants (Fig 3C). This additional delay could be due to protein folding [17]. In total, we found 34 homozygous mutant lineages in 25 microcolonies. Six microcolonies spawned multiple, separate homozygous mutant lineages, thus corroborating previous findings that recombineering may modify multiple genome copies in one cell [18]. Overall, a median of five generations was required to form homozygous mutants, consistent with our Fig 3. Single-cell analysis of fluorescent mutants. (A) Overlay of phase-contrast and fluorescence images showing a microcolony containing fluorescent mutants (see also S1 Movie). Yellow arrow: the first cell showing significantly higher fluorescence than background in the given frame. Accounting for the time required for YFP protein folding and maturation, the ssDNA integration is estimated to have happened before the first division of the labeled cell. (B) Genealogy of the aforementioned microcolony. The yellow arrow indicates the cell in A, while the remaining arrows indicate three lineages in which fluorescence was quantified. (C) YFP expression history of three lineages in B showing fully, transiently, and non-fluorescent phenotypes (green, blue, and red, respectively). Yellow dashed line: onset of fluorescence. Black and grey dashed lines correspond to the black and grey arrows in B. Black: emergence of the first homozygous mutant; grey: its first division. (D) Distribution of time to form 34 homozygous mutant lineages from 25 microcolonies. The data are obtained by directly analyzing genealogies as in B and compiled from two separate experiments. The dashed grey line indicates the estimated generations to form half of the homozygous mutant lineages. (E) Photo of a microcolony with one filamentous fluorescent cell. (F) The distribution of number of generations to form homozygous mutant lineages sorted by the presence/absence of filamentation. The numerical data for panels C, D, and F can be found in S1 Data. ssDNA, single-stranded DNA; YFP, yellow fluorescent protein. https://doi.org/10.1371/journal.pbio.2004644.g003 lacZ reporter assay results (Fig 3D). These results provide direct visual support that effective polyploidy underlies phenotypic delay. A similar pattern has been observed previously in E. coli with fimbrial switching, a genetic modification that involves inversion of a promoter sequence on the bacterial genome [19]. Electroporation, as used in the recombineering protocol, may cause bacteria to form filaments due to stress [20]. Filamentation might exacerbate phenotypic delay by increasing the intracellular genome copy number. Our single-cell experiment revealed that filamentation was indeed frequent (Fig 3E). By directly observing the cell shape and the time point for onset of fluorescence, we estimated that 18 out of 34 homozygous mutant lineages incorporated the ssDNA mutation into a filamentous ancestor cell. Strikingly, lineages initiated by filamentous cells showed a distinctly different distribution of time to form the first homozygous mutant than nonfilamentous lineages (Fig 3F). Nonfilamentous lineages showed a median of 4 generations until homozygosity, as would be required for cells that incorporated the mutation in 1 out of 16 DNA single strands (i.e., 8 chromosomes) in less than 1 generation post recombineering. In contrast, filamentous lineages showed a median of 6.5 generations, and all lineages requiring more than 6 generations were filamentous. In conclusion, both filamentous and nonfilamentous cells exhibit a multigenerational phenotypic delay. Filamentation, however, can exacerbate phenotypic delay presumably by increasing the number of chromosome copies within a cell, explaining particularly long delays of 5 or more generations sometimes observed in our experiments. Effects of chromosomal location on mutagenesis and delay Because phenotypic delay arises from effective polyploidy, one would expect genes further from the replication origin with lower ploidy than origin-proximal genes to show shorter phenotypic delay. However, we observed a similar phenotypic delay and distribution of time until homozygosity for all three tested genes (Fig 2) despite different distances from the origin. Further analysis revealed a strong negative correlation between distance to origin and the initial frequency of genotypic mutants induced by recombineering (Fig 4A and 4B). We hypothesized that these observations reflect the mechanism of mutagenesis by recombineering. Because open replication forks are required for recombineering, mutations could only be introduced during DNA replication [21]. The probability of successful mutagenesis on at least one open chromosomal target increases with ploidy, which itself increases during DNA replication. Therefore, we hypothesized that instead of mutating at low ploidy and thereby exhibiting shorter phenotypic delay, most of our observed origin-distal mutations were generated when their targets transiently reached higher ploidy either during normal DNA replication or due to cell filamentation. Therefore, consistent with our observations so far, origin-distal mutations would show phenotypic delay similar to origin-proximal mutations but reduced recombineering efficiency because origin-distal genes are less accessible for mutagenesis. To further test this hypothesis, we inferred a minimal ploidy of the aforementioned target sites at the precise time point of ssDNA integration with an adapted lacZ reporter assay that measured the fraction of mutant cells in mutant colonies directly after recombineering (Materials and methods). Overall, the distributions of ploidy were similar for the three tested chromosomal locations at 5.5%, 9.7%, and 34.2% genome distance from the origin (Fig 4C). This result potentially explains why we observed no effect of chromosomal location on phenotypic delay. Furthermore, this principle should apply not only to recombineering but also to natural mutations that arise during DNA replication. Effective polyploidy and phenotypic delay affect mutation rate estimation Fluctuation tests are widely used to estimate bacterial mutation rates by counting mutants exhibiting a selectable phenotype. Selection is typically applied to stationary phase cells [23], which are expected to be polyploid [10,22]. That polyploidy should affect the appearance of mutants in the fluctuation test was already pointed out quite early in the literature [24,25], but subsequently this consideration largely fell by the wayside. When a mutation arises in an effectively polyploid cell, the first homozygous mutant descendant must appear as a single cell in the population (Fig 5). Therefore, in contrast with earlier interpretations [1], the frequent observation of singletons in the mutant distribution does not invalidate the existence of a substantial phenotypic delay. Furthermore, because heterozygous cells carrying recessive mutations do not exhibit the mutant phenotype, i.e., cannot form colonies on selective plates in the fluctuation test, these unobserved mutants should result in an underestimation of the mutation rate. Incidentally, the phage or antibiotic resistance mutations typically used in fluctuation tests are recessive [11,12,26]. The impact of polyploidy on mutation rate estimation from fluctuation tests using the modern “gold standard” maximum likelihood method [23] has not been examined. Although one recent study considered the “segregation lag” for recessive mutations resulting from polyploidy [27], corrections to mutation rate estimators were only derived for two simpler methods with limited range of accuracy and low statistical efficiency relative to the maximum likelihood method [23]. Furthermore, these derivations neglected the key point that not all descendants of heterozygous mutants will be mutants themselves. We investigated the effect of polyploidy on observed mutant distributions, and thus estimated mutation rates, for both dominant and recessive mutations by simulating fluctuation tests. Our simulation model assumed fixed effective ploidy at the target by doubling and symmetrically dividing chromosome copies upon division according to a model of segregation that is justified for E. coli (Materials and methods). Importantly, this model leads to the shortest possible time to homozygosity and thus a conservative estimate of lag; however, other Fig 5. Reconciling Luria-Delbrück fluctuation test with phenotypic delay by effective polyploidy. (A) The original Luria-Delbrück mutation model disregards polyploidy. For instance, a phenotypic delay of two generations results in four mutants appearing at once. (B) The observation of many one-mutant (“singleton”) populations was interpreted as evidence against the existence of a delay [1,3]. (C) With polyploidy considered, cells with four genome copies require two divisions to generate a homozygous mutant that expresses a selectable recessive phenotype. Therefore, a delay of two generations can generate just one mutant. (D) Heterozygous cells containing recessive mutations will not survive selection, leading to an underestimation of mutational events. https://doi.org/10.1371/journal.pbio.2004644.g005 models of segregation in bacteria and archaea are possible [27,28]. From simulated cultures, we counted phenotypic mutants given either a completely dominant or a completely recessive mutation, assuming instant protein equilibration, and estimated mutation rates using standard maximum likelihood methods [23,29,30]. Other than polyploidy and dominance considerations, all modelling assumptions are the same as the standard approach (Materials and methods), allowing us to isolate the effect of ploidy. Under our model, ploidy $c$ has two effects relative to monoploidy: (i) it increases the number of mutation targets and thus the per-cell mutation rate by a factor $c$, and (ii) it generates initially heterozygous mutants that, after a delay of $\log_2 c$ generations, produce one out of $c$ homozygous mutant descendants (S1 Fig). The mutation rate estimate at the mutational target can be compared to the actual per-copy rate $\mu_c$ and per-cell rate $c \mu_c$ used in the simulations (Fig 6A and 6B). When $c = 1$ (monoploidy), as the standard method assumes, the estimate indeed reflects the per-copy or (equivalently) per-cell rate. For $c > 1$, the estimate is higher for dominant than for recessive traits. Surprisingly, for recessive traits, the estimate tends to coincide with the per-copy rate $\mu_c$ regardless of ploidy. For dominant traits, the estimate lies between the per-copy and per-cell rates, with confidence interval size increasing with ploidy. These patterns are robust across a range of parameter values (S2 Fig). In fact, these effects have a precise mathematical explanation (S1 Text section 2.2): the distribution of mutant counts in a polyploid population turns out to match the standard (monoploid) model with rescaled mutational influx in the case of a recessive trait (Fig 6C and S3A Fig) but fundamentally differs for a dominant trait (Fig 6D and S3B Fig). Therefore, for more commonly used recessive traits, estimates reflect mutation rates per target copy, which can be scaled up to per genome copy. This could explain why per-nucleotide mutation rates estimated from different targets do not differ significantly, despite differences in target location that potentially influence their copy number [31]. We then asked whether effective polyploidy impacts mutation rate estimates based on whole-genome sequencing (WGS) as well as fluctuation tests. WGS is typically conducted on evolved populations from mutation accumulation (MA) assays, which use single-cell bottlenecking to minimize selection [31]. Under the simplifying assumptions of fixed generation time and no cell death, we modeled an MA assay by tracking the single lineage that passes through each bottleneck and is ultimately sampled for sequencing (S1 Text section 3 and S4 Fig). Accounting for polyploidy, the per-cell mutation rate is $c \mu_g$, where $\mu_g$ is the per-genome-copy mutation rate. However, due to asymmetric inheritance, only a fraction $1/c$ of descendants from a mutant progenitor will eventually become homozygous mutants. Therefore, only a fraction $1/c$ of mutations arising in the focal lineage will ultimately be sampled, leaving the per-genome copy rate $\mu_g$ as the inferred mutation rate (S1 Text section 3). We therefore conclude that neither the fluctuation test nor WGS methods can accurately capture the per-cell mutation rate. Therefore, as the typical assumption is one genome per cell, neglecting polyploidy underestimates the total influx of de novo mutations in bacterial populations, which is relevant for adaptation. **Polyploidy and phenotypic delay impact bacterial evolvability under selection** Effective polyploidy has important consequences for evolutionary adaptation, both through the aforementioned increased influx of mutations and the masking of recessive mutations’ phenotype. Masking of deleterious recessive mutations is expected to increase their frequency in the standing genetic variation (SGV) and yield transiently lower, but eventually higher, mutational load in a fixed environment [28,32]. This higher standing frequency could promote adaptation to new environments should these mutations become beneficial. However, in an environment where mutations are beneficial, masking their effects should hinder adaptation. Previous theoretical studies addressing these conflicting effects of ploidy on adaptation [32,33] have not been linked to bacteria, nor have they specifically considered the chance of evolutionary rescue, i.e., rapid adaptation preventing extinction under sudden harsh environmental change (e.g., antibiotic treatment). Rescue mutations may preexist in the SGV and/or arise de novo after the environmental shift during residual divisions of wild-type cells. The source of rescue mutations has implications for the optimal approach to drug treatment [34] and the preservation of genetic diversity. following rescue [35]. To address the impact of effective polyploidy on rescue from SGV and de novo mutations, we developed a mathematical model of replication, mutations, and chromosome segregation in polyploid bacterial cells (Fig 7 and S1 Text section 4). We first derived the frequency of mutants in the SGV at mutation–selection balance in the "old" environment, where mutations continually arise at rate $\bar{m}$ per chromosome copy per replication and, if expressed, carry a fitness cost $s$ (S1 Text section 4.2). This yielded analytical expressions confirming that polyploidy increases the total frequency of a recessive mutant allele by masking its cost in heterozygotes. In contrast, the total mutant allele frequency is independent of ploidy if the mutation is dominant (Table 1 and S5 Fig). Next, we considered the fate of the population upon shifting to a new, harsh environment (e.g., antibiotic treatment), where phenotypically wild-type ("sensitive") cells have a low probability of successfully dividing while phenotypically mutant ("resistant") cells have a higher probability. The population may already contain heterozygous and homozygous mutants in the SGV and additionally give rise to de novo mutants stochastically according to a Poisson process. We developed a branching process model to evaluate the probability that such mutations escape stochastic extinction, accounting in particular for the multiple cell divisions required until mutations segregate to homozygosity, with probabilities of successful division depending on whether these mutations are recessive or dominant. Finally, combining these model components yielded expressions for the probability of population rescue from SGV, $P_{SGV}$, and from de novo mutations, $P_{DN}$ (S1 Text section 4.3). These rescue probabilities depend strongly on ploidy, dominance, and other model parameters (Fig 8, S6, S7, S8 and S9 Figs). In the recessive case, if phenotypically wild-type cells cannot divide in the new environment (e.g., a perfectly effective antibiotic), then $P_{SGV}$ is independent of ploidy, reflecting the constant frequency of preexisting phenotypically mutant homozygotes (Table 1). This result is consistent with our above findings for fluctuation tests. If division of wild-type cells is possible (e.g., imperfect antibiotic efficacy), then $P_{SGV}$ increases with ploidy because heterozygotes may produce additional homozygous mutant descendants. On the other hand, $P_{DN}$ decreases with ploidy because de novo mutations require more cell divisions until segregation is complete and the mutant phenotype is expressed, which turns out to outweigh the increase in mutational influx (S1 Text). Therefore, although the overall probability of rescue remains similar as ploidy increases, rescue is increasingly from SGV rather than de novo mutations (Fig 8A and 8B). These qualitative patterns are robust to variations in the model parameters (S6 and S8 Figs). For dominant mutations, on the other hand, both $P_{SGV}$ and $P_{DN}$ increase with ploidy, and their relative contributions can show more complex patterns (Fig 8C and 8D, S7 and S9 Figs). In general, SGV makes a relatively larger contribution when the mutation has a low cost in antibiotic-free conditions (small $s$) and when the antibiotic is highly effective (low $p_S$), in agreement with previous findings in the evolutionary rescue literature [36]. **Discussion** The phenotypic effect of a bacterial mutation cannot manifest instantaneously. Here, we therefore asked two questions: how large is this phenotypic delay, and what is its primary cause? We found a delay of three to four generations in the expression of three recessive antibiotic resistance mutations in *E. coli* and provided evidence that effective polyploidy is its primary cause. --- **Table 1. Approximate mutant frequencies at mutation–selection balance.** Ploidy is $c = 2^n$ ($n \geq 1$) in the polyploid cases, $\tilde{\mu}_i$ is the per-copy mutation rate, and $i$ is the cost of the mutation in homozygotes (in heterozygotes, the cost is masked in the recessive case but expressed in the dominant case). <table> <thead> <tr> <th></th> <th>Monoploid</th> <th>Polyploid recessive</th> <th>Polyploid dominant</th> </tr> </thead> <tbody> <tr> <td>Freq. of heterozyg. mutant cells (2$^i$ mutant chroms., 0 $\leq$ i $\leq$ n - 1)</td> <td>$-\tilde{\mu}_i$</td> <td>$2^{-i}\tilde{\mu}_i$</td> <td>$(1 - s)^i2^{-i}\tilde{\mu}_i$</td> </tr> <tr> <td>Freq. of homozyg. mutant cells (2$^n$ = c mutant chroms.)</td> <td>$\tilde{\mu}_i/s$</td> <td>$\tilde{\mu}_i/s$</td> <td>$(1 - s)^n\tilde{\mu}_i/s$</td> </tr> <tr> <td>Total freq. of mutant allele</td> <td>$\tilde{\mu}_i/s$</td> <td>$(n - 1)\tilde{\mu}_i + \tilde{\mu}_i/s$</td> <td>$\tilde{\mu}_i/s$</td> </tr> </tbody> </table> Abbreviation: Freq., frequency. https://doi.org/10.1371/journal.pbio.2004644.t001 Polyploidy is often regarded as a transient property limited to fast-growing bacteria, but this view has been challenged in recent years. Though ploidy tends to be higher during exponential growth (up to eight or 16 partial chromosome copies) [9], even during stationary phase, *E. coli* cells contain typically four and up to eight complete chromosome copies [10]. Environmental stresses can also induce multinucleated, polyploid cell filaments [37], in which adaptive mutations must overcome phenotypic delay before allowing population survival in deteriorating environments. A recent study exposing bacteria to low doses of the antibiotic ciprofloxacin showed that resistant bacteria can only emerge from mononucleated offspring. **Fig 8. Impact of effective polyploidy on the probability of evolutionary rescue.** (A, C) The probability that at least one mutation from the SGV survives in the new environment (*P*<sub>SGV</sub>; linear scale) and (B, D) the probability that at least one mutation arises in the new environment and survives (*P*<sub>DN</sub>; log scale), plotted as a function of ploidy, for a recessive mutation (A, B) or a dominant mutation (C, D). The different colored curves indicate probability of division before death of phenotypically wild-type (sensitive) cells in the new environment, *p*<sub>D</sub>, varying from 0 (black) to 0.45 (magenta) in increments of 0.05. The remaining parameters are fixed: probability of division before death of phenotypically mutant (resistant) cells, *p*<sub>R</sub> = 0.9; mutational cost in the old environment, *s* = 0.1; population size at the time the environment changes, *N* = 2 × 10<sup>8</sup>; and per-copy mutation rate, *μ*<sub>c</sub> = 3 × 10<sup>-10</sup>. This figure can be reproduced using code deposited on Dryad (http://dx.doi.org/10.5061/dryad.87233). SGV, standing genetic variation. https://doi.org/10.1371/journal.pbio.2004644.g008 cells that bud off from a long multinucleated cellular filament [37]. This observation can be explained by masking of the mutant phenotype in polyploid, heterozygous cells. Furthermore, obligate polyploid bacterial species ranging from free-living bacteria to clinically relevant pathogens have been discovered across six phyla [22,38,39]. This has, for instance, been recognized as a confounding factor in metagenomic studies of bacterial community structure by marker gene–based analysis [38]. Even within the same bacterial species, ploidy may vary in response to selection, as shown in a previous study that E. coli with resistance to camphor vapor also showed increased ploidy [40]. Therefore, we argue that polyploidy is broadly relevant for bacteria and will generally result in phenotypic delay of recessive mutations. Dominance and polyploidy (whether effective or obligate) together affect the number of mutants observed in fluctuation tests and thus require reinterpretation of mutation rate estimates. Fluctuation tests typically use recessive antibiotic resistance mutations. Encouragingly, we found that the resulting estimates accurately reflect the per–target copy mutation rate, regardless of ploidy. Therefore, studies using fluctuation tests to compare per–target copy mutation rates across different conditions, e.g., [41], remain valid. Similarly, we showed that sequencing-based methods of mutation rate estimation from MA assays reflect per-genome copy rates. Therefore, effective polyploidy does not appear to explain the up to 10-fold difference in mutation rate estimates [31,42] obtained using these two different methods. Importantly, however, neither method reflects the per-cell mutation rate and thus the total mutational influx in the population, which is proportional to ploidy. Indeed, our models suggest that fluctuation tests with recessive mutations or sequencing-based methods leave no detectable signal of ploidy in the data: that is, a polyploid population is indistinguishable from a monoploid population in these assays, even though their total mutational influx differs by a factor equal to the ploidy. Meanwhile, dominant mutations lead to fundamentally different mutant distributions in the fluctuation test, and neither the per-copy nor the per-cell mutation rate is accurately estimated. In conclusion, mutation rate estimates must be interpreted with caution, regardless of the method used. The effects of polyploidy on number of mutational targets and phenotypic delay influence the evolutionary potential of populations to escape extinction under sudden environmental change such as antibiotic treatment. In particular, we showed that recessive rescue mutations are increasingly likely to come from the SGV as ploidy increases. This is due to the dual effects of masking the fitness cost of these mutations in the old (antibiotic-free) environment while decreasing the chance that de novo mutations survive in the new (antibiotic) environment until their beneficial phenotype is expressed. Our novel results for rescue are broadly in line with previous theoretical findings on the role of ploidy for adaptation [32] and highlight the point that these considerations are relevant to bacteria as well as eukaryotes. Our theoretical results rest on several simplifying assumptions. Firstly, we examined only the cases of complete dominance or complete recessivity. More generally, gene dosage effects could result in intermediate dominance; in this case, we expect the effects on mutation rate estimation and rescue probability to be intermediate between the two extremes considered here. Secondly, while we examined rescue via single mutations, if multiple mutations with different dominance were available, populations at different ploidy levels may tend to evolve via different pathways [43]. Furthermore, while we exclusively considered chromosomal mutations, mutations on plasmids, particularly those with high copy number [44], should show similar effects, although segregation patterns and thus time to achieve homozygosity are likely to differ. Finally, models developed thus far have assumed constant ploidy, whereas future modeling efforts could incorporate the dynamically changing and environment-dependent nature of bacterial ploidy. Given the manifold implications of a multigenerational phenotypic delay, we argue that effective polyploidy and the resulting phenotypic delay are essential factors to consider in future studies of bacterial mutation and adaptation. Materials and methods Bacterial strains, antibiotics, and media All experiments were performed with strains derived from the wild-type *E. coli* MG1655 strain. A complete list of strains can be found in S2 Table. Cells were grown at 30˚C in LB or in M9 media with 0.4% lactose. Antibiotics were purchased from Sigma-Aldrich. To prepare stocks, rifampicin was dissolved in DMSO to 100 mg/ml; nalidixic acid was dissolved in 0.3 M NaOH solution to 30 mg/ml; streptomycin and ampicillin were dissolved in MilliQ water to 100 mg/ml and filter sterilized. Rifampicin, streptomycin, and ampicillin stocks were kept at −20˚C, while nalidixic acid was kept at 4˚C. Ampicillin 100 mg/L was used for maintaining the pSIM6 recombineering plasmid. All antibiotic agar plates were prepared fresh before every experiment. MIC determination The MICs of rifampicin, streptomycin, and nalidixic acid were determined by broth dilution method in LB and found to be 12 mg/L, 12 mg/L, and 6 mg/L, respectively. High-efficiency recombineering Our recombineering protocol was adapted from previous studies [6,21]. To ensure reproducibility, a detailed step-by-step protocol is provided in S1 Text section 1. In brief, *E. coli* harboring pSIM6 plasmids were grown into early exponential phase before heat activation at 43˚C for 10 minutes to express the recombineering proteins. Activated cells were then repeatedly washed in ice-cold MilliQ water to remove residual salts. Concentrated salt-free cell suspension 50 μl was then mixed with approximately 200 ng of ssDNA before electroporation at 1.8 kV/mm. Immediately after, electroporation cells were resuspended in LB and recovered for 30 min at 30˚C. After this initial recovery, cells were pelleted, then resuspended in fresh LB to continuously grow at 30˚C for subsequent phenotyping. Quantification of phenotypic delay of resistance mutations From the resuspended population, approximately 2% of cells were sampled hourly for the first 10 hours and then at 24 hours. A time point at 48 hours was also included to control for factors that potentially prevent phenotypic penetrance from ever reaching 100%, such as low establishment probability of mutant cells. The sampled populations were appropriately diluted for optimal plating onto selective and nonselective plates. Total population size and thus generations elapsed in the sampled cultures was estimated from colony-forming units (CFU) on nonselective plates. To score the frequency of genotypic mutants, we replica-plated all colonies from the nonselective plates to selective plates for each tested time point. The frequency of genotypic mutants, *Fg*, was determined by the fraction of colonies from nonselective plates that could grow after postponed replica plating onto selective plates. The frequency of phenotypic mutants, *Fp*, was determined by the ratio of CFU from immediate plating on selective plates versus CFU on nonselective plates. Phenotypic penetrance was defined as \[ P = \frac{F_p}{F_g} \] Phenotypic delay was then quantified as the time point at which phenotypic penetrance reaches 50%. Quantification of homozygosity To quantify mutant homozygosity, i.e., the fraction of homozygous mutants among all genotypic mutants, we developed a lacZ-based visual assay. We constructed bacterial strains with a lacZ gene disrupted by a nonsense point mutation (E461X) [8] and inserted the broken lacZ within 5 kb of each antibiotic resistance target gene. These strains were subjected to recombineering with an ssDNA carrying the reverse point mutation (X461E) that restored the lac+ phenotype. The resulting phenotypic mutants were selected on M9-lactose media. Phenotypic mutants become blue on permissive media containing 1 mM IPTG and 40 μg/ml X-gal [5]. Heterozygous mutants with mixed lac+/lac− alleles form blue-/white-sectored colonies, whereas homozygous mutants form entirely blue colonies (Fig 2E). Plates with colonies were left at 4˚C for 1 week to allow sufficient development of the blue color but before the blue pigment spreads too far to obscure sectored colonies. Counting sectored (s) and nonsectored (n) blue colonies, we determined mutant homozygosity as $f_{\text{hom}} = n/(s+n)$. Comparing $f_{\text{hom}}$ to the phenotypic penetrance $P$ thus indicates to what extent phenotypic delay is attributable to effective polyploidy. Colony counting was performed using CellProfiler [45]. Single-cell observations We constructed a strain with a constitutively expressed YFP gene disrupted by 3 consecutive stop codons. Recombineering corrected the stop codons. After electroporation and 30 min recovery at 30˚C, 1 μl of appropriately diluted cell suspension was pipetted onto a small 1.5% UltraPure Low Melting Point agarose pad. After drying the pad for 1 minute, it was deposited upside down in a sealed glass-bottom dish (WillCo Wells, GWST-5040). Time-lapse microscopy was performed with a fully automated Olympus IX81 inverted microscope, with 100X NA1.3 oil objective and Hamamatsu ORCA-flash 4.0 sCMOS camera. For fluorescent imaging, we used a Lumen Dynamics X-Cite120 lamp and Chroma YFP fluorescent filter (NA1028). The sample was maintained at 30˚C by a microscope incubator. Phase-contrast and yellow fluorescence images were captured at 5-minute intervals for 16 hours. The subsequent image analysis was performed with a custom-made MATLAB program (Vanellus, accessible at: http://kiviet.com/research/vanellus.php). Assessing minimal ploidy We performed the lacZ reporter assay, as described above, for three strains with lacZ gene juxtaposed to each of the antibiotic resistance target genes. After the 30-min recovery following recombineering (before extensive growth), cells were plated directly onto LB agar with IPTG and X-gal. After 24 hours of incubation at 30˚C, entire mutant colonies that contained blue color were picked. We started from colonies closest to the center of each agar plate and expanded outwards to eliminate picking bias. The picked colonies were diluted $10^4$- to $10^5$-fold in PBS before plating on average about 500 CFUs on fresh LB agar with IPTG and X-gal to infer the fraction of mutant cells in the given colony. This fraction was then used to deduce the minimal ploidy at the time of ssDNA integration based on a previous study [46]: a colony with one-quarter mutant cells, for instance, has minimal ploidy of 2 because it could have resulted from mutagenesis on 1 out of 4 DNA single strands. Actual ploidy may be higher if, for instance, 2 out of 8 single strands mutated in a cell of ploidy 4. Ploidy and chromosome segregation model For simplicity, we assumed every cell has the same effective ploidy, i.e., copies of the gene of interest, over the relevant timescale. At each generation, chromosomes must therefore undergo one round of replication and be evenly divided between the two daughter cells. In *E. coli*, chromosomes appear to progressively separate as they are replicated and detach last at the terminus [9]. We therefore assumed segregation into daughter cells occurs at the most ancestral split in the chromosome genealogy. This assumption is conservative because it implies that mutant chromosomes always remain together, resulting in the fastest possible approach to homozygosity and thus the shortest phenotypic delay. Under this model, ploidy must take the form $c = 2^n$ (for $n = 0, 1, 2, \ldots$), among which the number of mutant copies is $j = 0$ or $2^i$ ($0 \leq i \leq n$), while the remaining $c-j$ copies are wild type. Note that other models of segregation are possible, e.g., random segregation in highly polyploid Archaea [28], which would lead to slower approach to homozygosity and corresponding effects on the evolutionary model results. **Simulated fluctuation tests** All simulations and inference were implemented in R. We wrote our own code to account for polyploidy, but in the future, our methods could potentially be integrated into recently published R packages for fluctuation analysis [47,48]. We simulated culture growth in nonselective media with stochastic appearance of spontaneous de novo mutations (for details see S1 Text section 3.1). We assumed a fixed per-copy mutation rate of $\mu_c$ per wild-type cell division, such that the per-cell mutation rate is $\mu = c\mu_c$ for effective ploidy $c$. We neglected the chance of more than one copy mutating simultaneously, i.e., mutants always arose with the mutation in a single chromosome copy. Although natural mutations may initially arise in either single- or double-stranded form (for instance, mismatches versus indels following double-strand breaks), to be consistent with the standard model, we assumed mutations arose in double-stranded form (see discussion in S1 Text sections 2.1 and 2.3). The descendants of each de novo mutant were tracked individually, with mutant chromosomes segregating as described above and interdivision times either drawn independently from an exponential distribution or constant. We assumed no fitness differences between wild-type and mutant in nonselective media. In the case of $c = 1$ and exponential interdivision times, our model corresponds to the standard “Lea-Coulson” model [23,30], which is also the basis of the widely used software FALCOR [49]. Each simulated culture was initiated with 1,000 wild-type cells, and—after 20 wild-type population doublings—the culture growth phase ended and phenotypic mutants were counted under the assumption of either complete recessivity (requiring all $c$ chromosomes to be mutant) or complete dominance (requiring at least one mutant chromosome). Assuming (as standard) 100% plating efficiency and no growth of phenotypically wild-type cells under selective conditions, the number of colonies formed on selective plates equals the number of phenotypic mutants in the final culture. The mutant colony counts from 50 simulated parallel cultures were then used to obtain a maximum likelihood estimate (MLE) $\hat{\mu}$ and 95% profile likelihood confidence intervals of mutation rate under the standard model, which in particular assumes that a de novo mutant and all its descendants are immediately phenotypically mutant. The best-fitting distribution of mutant counts was calculated from the standard model with mutation rate equal to $\hat{\mu}$. While we implemented these calculations in R (code available on Dryad: http://dx.doi.org/10.5061/dryad.8723t), calculation of the likelihood under this model has been previously described [29,50] and has also been implemented in FALCOR [49]. **Mutation–selection balance** We considered a population with effective ploidy $c$, in which mutations arise (again, in double-stranded form) in a proportion $\mu = c\mu_i$ of offspring in each generation. The definition of mutation rate used in the population genetics literature is subtly different from that used in fluctuation analysis and thus given different notation here (see S1 Text section 4.2). The mutation has relative fitness cost $s$ in homozygotes, with the cost either completely masked (if recessive) or equal (if dominant) in heterozygotes. We extended deterministic genotype frequency recursions to incorporate chromosome segregation as described above and solved for the equilibrium frequencies of all heterozygous and homozygous mutant types (S1 Text section 4.2). **Evolutionary rescue** We modeled the fate of a population shifted to a harsh new environment, i.e., either extinction or rescue by mutants, stochastically using a multitype branching process. Unlike in the fluctuation test simulations, where we neglected the chance that wild-type cells produce surviving lineages in the new environment, here we allowed a probability $p_S \leq \frac{1}{2}$ that a phenotypically wild-type cell successfully divides before death to produce 2 offspring, while phenotypically mutant cells have corresponding probability $p_R > \frac{1}{2}$. Therefore, phenotypically wild-type cells cannot sustain themselves but have a nonzero chance of producing phenotypically mutant descendants either by segregation of mutant alleles in the SGV (modeled by mutation–selection balance as above) or de novo mutations during residual divisions in the new environment. We derived analytical approximations (S1 Text section 4.3) for the probability of rescue from SGV ($P_{SGV}$) or from de novo mutations ($P_{DN}$), which are not mutually exclusive. All data were deposited in the Dryad repository (http://dx.doi.org/10.5061/dryad.8723t) [51]. **Supporting information** S1 Text. Supplementary text with detailed recombineering protocol, model descriptions, and mathematical results. (PDF) S1 Table. List of mutations in this study. (DOCX) S2 Table. List of bacterial strains used in this study. (XLSX) S3 Table. List of oligonucleotides used in this study. (XLSX) S1 Data. Numerical values underlying the graphs in Figs 2, 3 and 4 and S10 Fig. (XLSX) S1 Fig. Schematic of cell lineage dynamics in a mutant clone. In this illustration, generation times are constant (synchronous division) for simplicity; ploidy $c = 4$ and a mutation arose in one copy. The existence of polyploidy implies that phenotypic mutants initially appear as singletons. For recessive traits, there is a delay of $\log_2 c$ generations after the de novo mutation until a single phenotypic mutant appears, then the number of phenotypic mutants doubles in each subsequent generation. For dominant traits, a single phenotypic mutant appears in the generation that the de novo mutation occurs but remains a singleton for $\log_2 c$ additional generations before the number of phenotypic mutants begins to double. In both cases, in the long term, a fraction $1/c$ of descendants are expected to be homozygous mutants and the rest wild type. (TIF) S2 Fig. Mutation rate estimates from simulated fluctuation tests. For various per-copy mutation rates $\mu_c$ (columns), for either constant (top row of each panel) or exponentially distributed (bottom row) interdivision times, and for each ploidy level $c$, 50 parallel cultures were simulated to make up one experiment. From each simulated culture, phenotypic mutants were counted assuming either (A) a recessive or (B) a dominant trait. This was repeated for two independent experiments (square and triangle symbols) for each parameter set. The MLE of mutation rate and 95% profile likelihood confidence intervals are plotted as a function of ploidy. In each panel, the lower solid black line indicates the actual per-copy mutation rate ($\mu_c$) and the upper black dashes indicate the per-cell mutation rate ($c\mu_c$). The results from the first simulated experiment with $\mu_c = 3 \times 10^{-10}$ and constant interdivision times correspond to the main text Fig 6A and 6B. This figure can be reproduced using code and simulated data deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). MLE, maximum likelihood estimate. (TIF) S3 Fig. Mutant count distributions from simulated fluctuation tests. At each ploidy level, assuming the trait is either recessive (A) or dominant (B), the observed mutant count across 50 simulated parallel cultures is plotted as a histogram. The simulated data are the same as that used in S2 Fig for the first experiment with per-copy mutation rate $\mu_c = 3 \times 10^{-10}$ and constant interdivision times. The distribution predicted by the standard model, parameterized by the maximum likelihood estimated mutation rate, is also plotted for comparison (connected points). The plots for ploidy $c = 4$ correspond to the main text Fig 6C and 6D. This figure can be reproduced using code and simulated data deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). (TIF) S4 Fig. Model of a MA experiment. (A) In an MA experiment, a bacterial population evolves for thousands of generations with single-colony bottlenecking every 25 to 30 generations. However, we track only the lineage of direct ancestors leading to the ultimately sampled single cell. (B) In a polyploid cell, acquiring a mutation yields a heterozygous mutant cell. For this mutation to fix in the sampled lineage and be detected by WGS, the daughter cell inheriting the mutant copies must be chosen at each cell division for further propagation in the sampled lineage. (C) Asymmetric inheritance caused by polyploidy reduces the fixation probability of mutations because the daughter cell inheriting the mutation may not be sampled. MA, mutation accumulation; WGS, whole-genome sequencing. (TIF) S5 Fig. Mutant allele frequency at mutation–selection balance. The frequency of the mutant allele is plotted as a function of its cost $s$, in the case of a completely recessive (A) or completely dominant (B) allele. In this example, ploidy $c = 2^n = 8$ and per-copy mutation rate $\bar{\mu}_c = 3 \times 10^{-10}$. The contribution to this frequency made by each cell type (given by $(2i/2^n)x_i^u$ in cells containing $2i$ mutant chromosomes) is represented by the shaded area between two curves, working up from the bottom through heterozygotes ($0 \leq i \leq n-1$) and then homozygotes ($i = n$). This figure can be reproduced using code deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). (TIF) S6 Fig. Probability of rescue with a recessive mutation as a function of probabilities of cell division before death. From left to right: probability of rescue from SGV, $P_{\text{SGV}}$; from de novo mutations, $P_{\text{DN}}$; from either or both, $P_{\text{tot}}$; and the ratio of probabilities, $P_{\text{SGV}}/P_{\text{DN}}$ (on log scale). The missing values (white) occur where $P_{DN} = 0$ and the ratio is undefined. All quantities are plotted as functions of the probabilities of division before death of sensitive cells ($p_S$; horizontal axis) and resistant cells ($p_R$; vertical axis). Ploidy ($c$) varies by row as indicated. Additional model parameters $s = 0.1$ and $m = 0.06$ are fixed. This figure can be reproduced using code deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). SGV, standing genetic variation. **S7 Fig.** Probability of rescue with a dominant mutation as a function of probabilities of cell division before death. All plotting parameters are identical to S6 Fig. This figure can be reproduced using code deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). **S8 Fig.** Probability of rescue with a recessive mutation as a function of mutational influx and cost. From left to right: probability of rescue from SGV, $P_{SGV}$; from de novo mutations, $P_{DN}$; from either or both, $P_{tot}$; and the ratio of probabilities, $P_{SGV}/P_{DN}$ (on log scale). All quantities are plotted as functions of the base-10 log of mutational influx ($\log_{10}(m) = \log_{10}(N\mu_i)$; horizontal axis in each plot) and the cost of the mutation in the old environment ($s$; vertical axis in each plot). Ploidy ($c$) varies by row as indicated. Additional model parameters $p_S = 0.2$ and $p_R = 0.9$ are fixed. This figure can be reproduced using code deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). SGV, standing genetic variation. **S9 Fig.** Probability of rescue with a dominant mutation as a function of mutational influx and cost. All plotting parameters are identical to S8 Fig. This figure can be reproduced using code deposited on Dryad (http://dx.doi.org/10.5061/dryad.8723t). **S10 Fig.** An example of a growth curve from the phenotypic delay experiments. The illustrated growth curve is from the Rif recombineering experiment. Sampling occurred during the first 10 hours after recombineering, with the first sample taken at 0.5 h immediately after recovery from electroporation. Population doublings, expressed in number of generations after the first sampling time point, is calculated based on CFU counts at each sampling time. Red dots indicate individual data points from each of six replicates sampled at each time. The black line shows a linear regression of how generation time depends on real time expressed in hours, fitted through the mean of the replicates at each time point. The numerical values can be found in S1 Data. CFU, colony-forming unit. **S1 Movie.** Time-lapse film of the bacterial microcolony shown in Fig 3A. **Acknowledgments** We thank Erik Wistrand-Yuen, Erik Lundin, and Gerrit Brandis from the groups of Dan I. Andersson and Diarmaid Hughes at Uppsala University for kindly gifting us some bacterial strains and plasmids. We also thank Sébastien Wielgoss, Gabriel Leventhal, Andrew Read, and Min Wu for helpful discussions. **Author Contributions** Conceptualization: Lei Sun, Helen K. Alexander, Martin Ackermann, Sebastian Bonhoeffer. Formal analysis: Lei Sun, Helen K. Alexander, Balazs Bogos, Daniel J. Kiviet. Funding acquisition: Martin Ackermann, Sebastian Bonhoeffer. Investigation: Lei Sun, Helen K. Alexander, Balazs Bogos, Daniel J. Kiviet. Methodology: Lei Sun, Helen K. Alexander, Balazs Bogos, Daniel J. Kiviet. Project administration: Sebastian Bonhoeffer. Supervision: Martin Ackermann, Sebastian Bonhoeffer. Writing – original draft: Lei Sun, Helen K. Alexander, Sebastian Bonhoeffer. Writing – review & editing: Lei Sun, Helen K. Alexander, Balazs Bogos, Daniel J. Kiviet, Martin Ackermann, Sebastian Bonhoeffer. References
Abstract User documentation for developers using X DevAPI. For legal information, see the Legal Notices. For help with using MySQL, please visit the MySQL Forums, where you can discuss your issues with other MySQL users. Document generated on: 2022-03-23 (revision: 72434) # Table of Contents Preface and Legal Notices ........................................................................................................... v 1 Overview ...................................................................................................................................... 1 2 Connection and Session Concepts .............................................................................................. 3 2.1 Database Connection Example ............................................................................................. 3 2.2 Connecting to a Session ........................................................................................................ 4 2.2.1 Connecting to a Single MySQL Server ........................................................................ 4 2.2.2 Connection Option Summary ..................................................................................... 5 2.2.3 Connection Attributes ............................................................................................... 5 2.3 Working with a Session Object ............................................................................................ 6 2.4 Using SQL with Session ....................................................................................................... 7 2.5 Setting the Current Schema ............................................................................................... 7 2.6 Dynamic SQL ..................................................................................................................... 8 3 CRUD Operations ....................................................................................................................... 9 3.1 CRUD Operations Overview ............................................................................................... 9 3.2 Method Chaining .................................................................................................................. 10 3.3 Parameter Binding ............................................................................................................... 10 3.4 MySQL Shell Automatic Code Execution ......................................................................... 11 4 Working with Collections ......................................................................................................... 15 4.1 Basic CRUD Operations on Collections .............................................................................. 15 4.2 Collection Objects ............................................................................................................... 16 4.2.1 Creating a Collection ................................................................................................. 16 4.2.2 Working with Existing Collections ......................................................................... 16 4.3 Collection CRUD Function Overview ............................................................................... 16 4.4 Indexing Collections ......................................................................................................... 23 4.5 Single Document Operations ............................................................................................ 26 4.6 JSON Schema Validation ................................................................................................... 27 5 Working with Documents .......................................................................................................... 29 5.1 Creating Documents ........................................................................................................... 29 5.2 Working with Document IDs ............................................................................................ 29 5.3 Understanding Document IDs ......................................................................................... 31 6 Working with Relational Tables ............................................................................................... 33 6.1 Syntax of the SQL CRUD Functions .................................................................................. 33 7 Working with Relational Tables and Documents ..................................................................... 37 7.1 Collections as Relational Tables ........................................................................................ 37 8 Statement Execution ................................................................................................................ 39 8.1 Transaction Handling ......................................................................................................... 39 8.1.1 Processing Warnings ................................................................................................. 40 8.1.2 Error Handling ......................................................................................................... 41 8.2 Working with Savepoints .................................................................................................. 42 8.3 Working with Locking ....................................................................................................... 43 8.4 Working with Prepared Statements ................................................................................... 44 9 Working with Result Sets ......................................................................................................... 47 9.1 Result Set Classes ............................................................................................................... 47 9.2 Working with AUTO_INCREMENT Values ....................................................................... 48 9.3 Working with Data Sets ..................................................................................................... 48 9.4 Fetching All Data Items at Once ....................................................................................... 49 9.5 Working with SQL Result Sets ........................................................................................ 50 9.6 Working with Metadata .................................................................................................... 52 9.7 Support for Language Native Iterators ............................................................................ 52 10 Building Expressions ............................................................................................................. 55 10.1 Expression Strings ........................................................................................................... 55 Preface and Legal Notices This is the X DevAPI User Guide for MySQL Shell in JavaScript mode. 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Chapter 1 Overview This guide explains how to use the X DevAPI and provides examples of its functionality. The X DevAPI is implemented by MySQL Shell and MySQL Connectors that support X Protocol. For more background information and instructions on how to install and get started using X DevAPI, see Using MySQL as a Document Store. For quick-start tutorials introducing you to X DevAPI, see JavaScript Quick-Start Guide: MySQL Shell for Document Store and Python Quick-Start Guide: MySQL Shell for Document Store. In addition to this documentation, there is developer documentation for all X DevAPI methods in the API references, available from Connectors and APIs. This section introduces the X DevAPI and provides an overview of the features available when using it to develop applications. The X DevAPI wraps powerful concepts in a simple API. - A new high-level session concept enables you to write code that can transparently scale from single MySQL Server to a multiple server environment. See Chapter 2, Connection and Session Concepts. - Read operations are simple and easy to understand. - Non-blocking, asynchronous calls follow common host language patterns. The X DevAPI introduces a new, modern, and easy-to-learn way to work with your data. - Documents are stored in Collections and have their dedicated CRUD operation set. See Chapter 4, Working with Collections and Chapter 5, Working with Documents. - Work with your existing domain objects or generate code based on structure definitions for strictly typed languages. See Chapter 5, Working with Documents. - Focus is put on working with data via CRUD operations. See Section 3.1, “CRUD Operations Overview”. - Modern practices and syntax styles are used to get away from traditional SQL-String-Building. See Chapter 10, Building Expressions for details. Chapter 2 Connection and Session Concepts Table of Contents 2.1 Database Connection Example ................................................................. 3 2.2 Connecting to a Session ........................................................................... 4 2.2.1 Connecting to a Single MySQL Server ........................................... 4 2.2.2 Connection Option Summary ......................................................... 5 2.2.3 Connection Attributes ................................................................. 5 2.3 Working with a Session Object ............................................................... 6 2.4 Using SQL with Session .......................................................................... 7 2.5 Setting the Current Schema .................................................................... 7 2.6 Dynamic SQL ........................................................................................... 8 This section explains the concepts of connections and sessions as used by the X DevAPI. Code examples for connecting to a MySQL Document Store (see Using MySQL as a Document Store) and using sessions are provided. An X DevAPI session is a high-level database session concept that is different from working with traditional low-level MySQL connections. Sessions can encapsulate one or more actual MySQL connections when using the X Protocol. Use of this higher abstraction level decouples the physical MySQL setup from the application code. Sessions provide full support of X DevAPI and limited support of SQL. For MySQL Shell, when a low-level MySQL connection to a single MySQL instance is needed this is still supported by using a ClassicSession, which provides full support of SQL. Before looking at the concepts in more detail, the following examples show how to connect using a session. 2.1 Database Connection Example The code that is needed to connect to a MySQL document store looks a lot like the traditional MySQL connection code, but now applications can establish logical sessions to MySQL server instances running the X Plugin. Sessions are produced by the mysqlx factory, and the returned sessions can encapsulate access to one or more MySQL server instances running X Plugin. Applications that use Session objects by default can be deployed on both single server setups and database clusters with no code changes. Create an X DevAPI session using the mysqlx.getSession(connection) method. You pass in the connection parameters to connect to the MySQL server, such as the hostname and user, very much like the code in one of the classic APIs. The connection parameters can be specified as either a URI type string, for example user:@localhost:33060, or as a data dictionary, for example {user: myuser, password: mypassword, host: example.com, port: 33060}. See Connecting to the Server Using URI-Like Strings or Key-Value Pairs for more information. The MySQL user account used for the connection should use either the mysql_native_password or caching_sha2_password authentication plugin, see Pluggable Authentication. The server you are connecting to should have encrypted connections enabled, the default in MySQL 8.0. This ensures that the client uses the X Protocol PLAIN password mechanism which works with user accounts that use either of the authentication plugins. If you try to connect to a server instance which does not have encrypted connections enabled, for user accounts that use the mysql_native_password plugin authentication is attempted using MYSQL41 first, and for user accounts that use caching_sha2_password authentication falls back to SHA256_MEMORY. Connecting to a Session The following example code shows how to connect to a MySQL server and get a document from the `my_collection` collection that has the field `name` starting with `L`. The example assumes that a schema called `test` exists, and the `my_collection` collection exists. To make the example work, replace `user` with your username, and `password` with your password. If you are connecting to a different host or through a different port, change the host from `localhost` and the port from `33060`. ```javascript var mysqlx = require('mysqlx'); // Connect to server on localhost var mySession = mysqlx.getSession( { host: 'localhost', port: 33060, user: 'user', password: 'password' } ); var myDb = mySession.getSchema('test'); // Use the collection 'my_collection' var myColl = myDb.getCollection('my_collection'); // Specify which document to find with Collection.find() and // fetch it from the database with .execute() var myDocs = myColl.find('name like :param').limit(1). bind('param', 'L%').execute(); // Print document print(myDocs.fetchOne()); mySession.close(); ``` 2.2 Connecting to a Session There are several ways of using a session to connect to MySQL depending on the specific setup in use. This section explains the different methods available. 2.2.1 Connecting to a Single MySQL Server In this example a connection to a local MySQL Server instance running X Plugin on the default TCP/IP port `33060` is established using the MySQL user account `user` with its password. As no other parameters are set, default values are used. ```javascript // Passing the parameters in the { param: value } format var dictSession = mysqlx.getSession( { host: 'localhost', 'port': 33060, user: 'user', password: 'password' } ) var db1 = dictSession.getSchema('test') // Passing the parameters in the URI format var uriSession = mysqlx.getSession('user:password@localhost:33060') var db2 = uriSession.getSchema('test') ``` The following example shows how to connect to a single MySQL Server instance by providing a TCP/IP address “localhost” and the same user account as before. You are prompted to enter the user name and password in this case. ```javascript // Passing the parameters in the { param: value } format // Query the user for the account information print("Please enter the database user information."); var usr = shell.prompt("Username: ", {defaultValue: "user"}); var pwd = shell.prompt("Password: ", {type: "password"}); // Connect to MySQL Server on a network machine ``` Connection Option Summary When using an X DevAPI session the following options are available to configure the connection. <table> <thead> <tr> <th>Option</th> <th>Name</th> <th>Optional</th> <th>Default</th> <th>Notes</th> </tr> </thead> <tbody> <tr> <td>TCP/IP Host</td> <td>host</td> <td>-</td> <td>localhost, IPv4 host name, no IP-range</td> <td>localhost, IPv4 host name, no IP-range</td> </tr> <tr> <td>TCP/IP Port</td> <td>port</td> <td>Yes</td> <td>33060</td> <td>Standard X Plugin port is 33060</td> </tr> <tr> <td>MySQL user</td> <td>dbUser</td> <td>-</td> <td></td> <td>MySQL database user</td> </tr> <tr> <td>MySQL password</td> <td>dbPassword</td> <td>-</td> <td></td> <td>The MySQL user's password</td> </tr> </tbody> </table> Supported authentication methods are: - PLAIN - MYSQL 4.1 URI elements and format. **Figure 2.1 Connection URI** ``` ConnectURI1::= 'dbUser' ':' 'dbPassword' '@' 'host' ':' 'port' ``` 2.2.3 Connection Attributes **Connection attributes** are key-value pairs that application programs can pass to the server during connection time to be stored in the PERFORMANCE_SCHEMA tables `session_account_connect_attrs` and `session_connect_attrs`. There are two different kinds of connection attributes: - Client-defined attributes are reserved key-value mappings implicitly encoded by a client. The set of client-defined attributes differ from client to client—see the X DevAPI references of you client for details. The client-defined attributes are sent to the server by default. - User-defined attributes are key-value mappings provided by the user or application. X DevAPI supports MySQL connection attributes through the connection parameter `connection-attributes` (`xdevapi.connection-attributes` for Connector/J), set through the `getSession()` and `getClient()` methods. Here are the different ways to use the parameter: - These settings for the parameter are equivalent to the default behavior (that is, sending client-defined attributes) when the parameter is not used: • **connection-attributes** • **connection-attributes=** • **connection-attributes=true** • **connection-attributes=[]** • **connection-attributes=false** prevents any connection attributes to be sent, including the client-defined ones. • **connection-attributes=[key1=value1, key2=value2, ...]** sends user-defined connection attributes as key-value pairs alongside the client-defined connection attributes. When a value is missing from a key-value pair, a null value is set for the attribute. The following is a generic example of a connection string that configures the connection attributes: ``` mysqlx://user:password@localhost:33060?connection-attributes=[key1=value1, key2=value2, key3=] ``` ### 2.3 Working with a Session Object All previous examples used the `getSession()` or `getDefaultSchema()` methods of the Session object, which return a Schema object. You use this Schema object to access Collections and Tables. Most examples make use of the X DevAPI ability to chain all object constructions, enabling you to get to the Schema object in one line. For example: ``` schema = mysqlx.getSession(...).getSchema(); ``` This object chain is equivalent to the following, with the difference that the intermediate step is omitted: ``` session = mysqlx.getSession(); schema = session.getSchema(); ``` There is no requirement to always chain calls until you get a Schema object, neither is it always what you want. If you want to work with the Session object, for example, to call the Session object method `getSchemas()`, there is no need to navigate down to the Schema. For example: ``` session = mysqlx.getSession(); session.getSchemas(); ``` In this example the `mysqlx.getSession()` function is used to open a Session. Then the `Session.getSchemas()` function is used to get a list of all available schemas and print them to the console. ```javascript // Connecting to MySQL and working with a Session var mysqlx = require('mysqlx'); // Connect to a dedicated MySQL server using a connection URI var mySession = mysqlx.getSession('user:password@localhost'); // Get a list of all available schemas var schemaList = mySession getSchemas(); print('Available schemas in this session: '); // Loop over all available schemas and print their name for (index in schemaList) { print(schemaList[index].name + 'n'); } ``` 2.4 Using SQL with Session In addition to the simplified X DevAPI syntax of the Session object, the Session object has a `sql()` function that takes any SQL statement as a string. The following example uses a Session to call an SQL Stored Procedure on the specific node. ```javascript var mysqlx = require('mysqlx'); // Connect to server using a Session var mySession = mysqlx.getSession('user:password@localhost'); // Switch to use schema 'test' mySession.sql("USE test").execute(); // In a Session context the full SQL language can be used mySession.sql("CREATE PROCEDURE my_add_one_procedure " + " (INOUT incr_param INT) " + " BEGIN " + " SET incr_param = incr_param + 1;" + " END;").execute(); mySession.sql("SET @my_var = ?;`).bind(10).execute(); mySession.sql("CALL my_add_one_procedure(@my_var);`).execute(); mySession.sql("DROP PROCEDURE my_add_one_procedure;`).execute(); // Use an SQL query to get the result var myResult = mySession.sql("SELECT @my_var").execute(); // Gets the row and prints the first column var row = myResult.fetchOne(); print(row[0]); mySession.close(); ``` When using literal/verbatim SQL the common API patterns are mostly the same compared to using DML and CRUD operations on Tables and Collections. Two differences exist: setting the current schema and escaping names. 2.5 Setting the Current Schema A default schema for a session can be specified using the `schema` attribute in the URI-like connection string or key-value pairs when opening a connection session. The `Session` class `getDefaultSchema()` method returns the default schema for the `Session`. If no default schema has been selected at connection, the `Session` class `setCurrentSchema()` function can be used to set a current schema. ```javascript var mysqlx = require('mysqlx'); // Direct connect with no client-side default schema specified var mySession = mysqlx.getSession('user:password@localhost'); mySession.setCurrentSchema("test"); Notice that `setCurrentSchema()` does not change the session's default schema, which remains unchanged throughout the session, or remains `null` if not set at connection. The schema set by `setCurrentSchema()` can be returned by the `getCurrentSchema()` method. An alternative way to set the current schema is to use the `Session` class `sql()` method and the `USE db_name` statement. 2.6 Dynamic SQL A quoting function exists to escape SQL names and identifiers. `Session.quoteName()` escapes the identifier given in accordance to the settings of the current connection. **Note** The quoting function must not be used to escape values. Use the value binding syntax of `Session.sql()` instead; see Section 2.4, “Using SQL with Session” for some examples. ```javascript function createTestTable(session, name) { // use escape function to quote names/identifier quoted_name = session.quoteName(name); session.sql("DROP TABLE IF EXISTS " + quoted_name).execute(); var create = "CREATE TABLE "; create += quoted_name; create += " (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT)"; session.sql(create).execute(); return session.getCurrentSchema().getTable(name); } var mysqlx = require('mysqlx'); var session = mysqlx.getSession('user:password@localhost:33060/test'); var default_schema = session.getDefaultSchema().name; session.setCurrentSchema(default_schema); // Creates some tables var table1 = createTestTable(session, 'test1'); var table2 = createTestTable(session, 'test2'); ``` Code that uses X DevAPI does not need to escape identifiers. This is true for working with collections and for working with relational tables. Chapter 3 CRU Operations Table of Contents 3.1 CRUD Operations Overview ................................................................. 9 3.2 Method Chaining ........................................................................... 10 3.3 Parameter Binding .......................................................................... 10 3.4 MySQL Shell Automatic Code Execution ....................................... 11 This section explains how to use the X DevAPI for Create Read, Update, and Delete (CRUD) operations. MySQL’s core domain has always been working with relational tables. X DevAPI extends this domain by adding support for CRUD operations that can be run against collections of documents. This section explains how to use these. 3.1 CRUD Operations Overview CRUD operations are available as methods, which operate on Schema objects. The available Schema objects consist of Collection objects containing Documents, or Table objects consisting of rows and Collections containing Documents. The following table shows the available CRUD operations for both Collection and Table objects. <table> <thead> <tr> <th>Operation</th> <th>Document</th> <th>Relational</th> </tr> </thead> <tbody> <tr> <td>Create</td> <td>Collection.add()</td> <td>Table.insert()</td> </tr> <tr> <td>Read</td> <td>Collection.find()</td> <td>Table.select()</td> </tr> <tr> <td>Update</td> <td>Collection.modify()</td> <td>Table.update()</td> </tr> <tr> <td>Delete</td> <td>Collection.remove()</td> <td>Table.delete()</td> </tr> </tbody> </table> Database Object Classes Figure 3.1 Database Object - Class Diagram 3.2 Method Chaining X DevAPI supports a number of modern practices to make working with CRUD operations easier and to fit naturally into modern development environments. This section explains how to use method chaining instead of working with SQL strings of JSON structures. The following example shows how method chaining is used instead of an SQL string when working with Session objects. The example assumes that the test schema exists and an employee table exists. ```javascript // New method chaining used for executing an SQL SELECT statement // Recommended way for executing queries var employees = db.getTable('employee'); var res = employees.select(['name', 'age']). where('name like :param'). orderBy(['name']). bind('param', 'm%').execute(); // Traditional SQL execution by passing an SQL string // It should only be used when absolutely necessary var result = session.sql('SELECT name, age ' + 'FROM employee ' + 'WHERE name like ? ' + 'ORDER BY name').bind('m%').execute(); ``` 3.3 Parameter Binding Instead of using values directly in an expression string it is good practice to separate values from the expression string. This is done using parameters in the expression string and the bind() function to bind values to the parameters. Parameters can be specified in the following ways: anonymous and named. <table> <thead> <tr> <th>Parameter Type</th> <th>Syntax</th> <th>Example</th> <th>Allowed in CRUD operations</th> <th>Allowed in SQL strings</th> </tr> </thead> <tbody> <tr> <td>Anonymous</td> <td>?</td> <td>'age &gt; ?'</td> <td>no</td> <td>yes</td> </tr> <tr> <td>Named</td> <td>:&lt;name&gt;</td> <td>'age &gt; :age'</td> <td>yes</td> <td>no</td> </tr> </tbody> </table> The following example shows how to use the bind() function before an execute() function. For each named parameter, provide an argument to bind() that contains the parameter name and its value. The order in which the parameter value pairs are passed to bind() is of no importance. The example assumes that the test schema has been assigned to the variable db and that the collection my_collection exists. ```javascript // Collection.find() function with fixed values var myColl = db.getCollection('my_collection'); var myRes1 = myColl.find('age = 18').execute(); // Using the .bind() function to bind parameters var myRes2 = myColl.find('name = :param1 AND age = :param2').bind('param1','Rohit').bind('param2', 18).execute(); // Using named parameters myColl.modify('name = :param').set('age', 55). bind('param', 'Nadya').execute(); // Binding works for all CRUD statements except add() var myRes3 = myColl.find('name like :param'). bind('param', 'R%').execute(); ``` Anonymous placeholders are not supported in X DevAPI. This restriction improves code clarity in CRUD command chains with multiple methods using placeholders. Regardless of the `bind()` syntax variant used there is always a clear association between parameters and placeholders based on the parameter name. All methods of a CRUD command chain form one namespace for placeholders. In the following example, `modify()` and `set()` are chained. Both methods take an expression with placeholders. The placeholders refer to one combined namespace. Both use one placeholder called `:param`. A single call to `bind()` with one name value parameter for `:param` is used to assign a placeholder value to both occurrences of `:param` in the chained methods. ```javascript // one bind() per parameter var myColl = db.getCollection('relatives'); var juniors = myColl.find('alias = "jr"').execute().fetchAll(); for (var index in juniors){ myColl.modify('name = :param'). set('parent_name',mysqlx.expr(':param')). bind('param', juniors[index].name).execute(); } ``` It is not permitted for a named parameter to use a name that starts with a digit. For example, `:1one` and `:1` are not allowed. ### Preparing CRUD Statements Instead of directly binding and executing CRUD operations with `bind()` and `execute()` or `execute()` it is also possible to store the CRUD operation object in a variable for later execution. The advantage of doing so is to be able to bind several sets of variables to the parameters defined in the expression strings and therefore get better performance when executing a large number of similar operations. The example assumes that the `test` schema has been assigned to the variable `db` and that the collection `my_collection` exists. ```javascript var myColl = db.getCollection('my_collection'); // Only prepare a Collection.remove() operation, but do not run it yet var myRemove = myColl.remove('name = :param1 AND age = :param2'); // Binding parameters to the prepared function and .execute() myRemove.bind('param1', 'Leon').bind('param2', 39).execute(); myRemove.bind('param1', 'Johannes').bind('param2', 28).execute(); // Binding works for all CRUD statements but add() var myFind = myColl.find('name like :param1 AND age > :param2'); var myDocs = myFind.bind('param1', 'L%').bind('param2', 20).execute(); var MyOtherDocs = myFind.bind('param1', 'J%').bind('param2', 25).execute(); ``` ### 3.4 MySQL Shell Automatic Code Execution When you use X DevAPI in a programming language that fully specifies the syntax to be used, for example, when executing SQL statements through an X DevAPI session or working with any of the CRUD operations, the actual operation is performed only when the `execute()` function is called. For example: ```javascript var result = mySession.sql('show databases').execute() var result2 = myColl.find().execute() ``` The call of the `execute()` function above causes the operation to be executed and returns a Result object. The returned Result object is then assigned to a variable, and the assignment is the last operation Automatic Code Execution executed, which returns no data. Such operations can also return a Result object, which is used to process the information returned from the operation. Alternatively, MySQL Shell provides the following usability features that make it easier to work with X DevAPI interactively: - Automatic execution of CRUD and SQL operations. - Automatic processing of results. To achieve this functionality MySQL Shell monitors the result of the last operation executed every time you enter a statement. The combination of these features makes using the MySQL Shell interactive mode ideal for prototyping code, as operations are executed immediately and their results are displayed without requiring any additional coding. For more information see MySQL Shell 8.0. **Automatic Code Execution** If MySQL Shell detects that a CRUD operation ready to execute has been returned, it automatically calls the `execute()` function. Repeating the example above in MySQL Shell and removing the assignment operation shows the operation is automatically executed. ```bash mysql-js> mySession.sql('show databases') mysql-js> myColl.find() ``` MySQL Shell executes the SQL operation, and as mentioned above, once this operation is executed a Result object is returned. **Automatic Result Processing** If MySQL Shell detects that a Result object is going to be returned, it automatically processes it, printing the result data in the best format possible. There are different types of Result objects and the format changes across them. ```bash mysql-ja> db.countryInfo.find().limit(1) [ { "GNP": 828, "IndepYear": null, "Name": "Aruba", "_id": "ABW", "demographics": { "LifeExpectancy": 78.4000015258789, "Population": 103000 }, "geography": { "Continent": "North America", "Region": "Caribbean", "SurfaceArea": 193 } ]``` "government": { "GovernmentForm": "Nonmetropolitan Territory of The Netherlands", "HeadOfState": "Beatrix" } Chapter 4 Working with Collections Table of Contents 4.1 Basic CRUD Operations on Collections .......................................................... 15 4.2 Collection Objects ............................................................................................ 16 4.2.1 Creating a Collection .................................................................................. 16 4.2.2 Working with Existing Collections ............................................................. 16 4.3 Collection CRUD Function Overview .............................................................. 16 4.4 Indexing Collections ......................................................................................... 23 4.5 Single Document Operations ........................................................................... 26 4.6 JSON Schema Validation .................................................................................. 27 The following section explains how to work with Collections, how to use CRUD operations on Collections and return Documents. 4.1 Basic CRUD Operations on Collections Working with collections of documents is straightforward when using X DevAPI. The following example shows the basic usage of CRUD operations (see Section 4.3, “Collection CRUD Function Overview” for more details) when working with documents: After establishing a connection to a MySQL Server instance, a new collection that can hold JSON documents is created and several documents are inserted. Then, a find operation is executed to search for a specific document from the collection. Finally, the collection is dropped again from the database. The example assumes that the test schema exists and that the collection my_collection does not exist. ```javascript // Connecting to MySQL Server and working with a Collection var mysqlx = require('mysqlx'); // Connect to server var mySession = mysqlx.getSession({ host: 'localhost', port: 33060, user: 'user', password: 'password' }); var myDb = mySession.getSchema('test'); // Create a new collection 'my_collection' var myColl = myDb.createCollection('my_collection'); // Insert documents myColl.add({name: 'Laurie', age: 19}).execute(); myColl.add({name: 'Nadya', age: 54}).execute(); myColl.add({name: 'Lukas', age: 32}).execute(); // Find a document var docs = myColl.find('name like :param1 AND age < :param2').limit(1). bind('param1','L%').bind('param2',20).execute(); // Print document print(docs.fetchOne()); // Drop the collection myDb.dropCollection('my_collection'); ``` 4.2 Collection Objects Documents of the same type (for example users, products) are grouped together and stored in the database as collections. X DevAPI uses Collection objects to store and retrieve documents. 4.2.1 Creating a Collection In order to create a new collection call the `createCollection()` function from a Schema object. It returns a Collection object that can be used right away to, for example, insert documents into the database. ```javascript // Create a new collection called 'my_collection' var myColl = db.createCollection('my_collection'); ``` 4.2.2 Working with Existing Collections In order to retrieve a Collection object for an existing collection stored in the database call the `getCollection()` function from a Schema object. ```javascript // Get a collection object for 'my_collection' var myColl = db.getCollection('my_collection'); ``` The `createCollection()`, together with the `ReuseExistingObject` field set to true, can be used to create a new collection or reuse an existing collection with the given name. See Section 4.2.1, “Creating a Collection” for details. Note In most cases it is good practice to create database objects during development time and refrain from creating them on the fly during the production phase of a database project. Therefore it is best to separate the code that creates the collections in the database from the actual user application code. 4.3 Collection CRUD Function Overview The following section explains the individual functions of the Collection object. The most common operations to be performed on a Collection are the Create Read Update Delete (CRUD) operations. In order to speed up find operations it is recommended to make proper use of indexes. Collection.add() The `Collection.add()` function is used to store documents in a collection, similar to the `INSERT` statement for a SQL database. It takes a single document or a list of documents as its argument, and is executed by the `execute()` function. The collection needs to be created with the `Schema.createCollection()` function before documents can be inserted. To insert documents into an existing collection use the `Schema.getCollection()` function to retrieve the Collection object. The following example shows how to use the `Collection.add()` function. The example assumes that the test schema exists and that the collection `my_collection` does not exist. ```javascript // Create a new collection var myColl = db.createCollection('my_collection'); // Insert a document myColl.add( {name: 'Laurie', age: 19 } ).execute(); // Insert several documents at once ``` Collection.find() myColl.add([ {name: 'Nadya', age: 54 }, {name: 'Lukas', age: 32 } ] ).execute(); See also CollectionAddFunction for the syntax of add() in EBNF. Collection.find() The find() function is used to search for documents in a collection, similar to the SELECT statement for a SQL database. It takes a search condition string (SearchConditionStr) as a parameter to specify the documents that should be returned from the database. The execute() function triggers the actual execution of the find() operation. The SearchConditionStr can be in one of these forms: - If no SearchConditionStr is specified, the find() operation returns all the documents in the collection. ```java // Get a collection var myColl = session.getSchema("world_x").getCollection("countryinfo"); // To return all documents in world_x: myColl.find().execute(); ``` - The most common form for a SearchConditionStr is: JSON-path [ operator { value | JSON-path} ] Here are some explanations for the different parts of a SearchConditionStr: - JSON-path: A JSON path identifies an element in a JSON document; see JSON Path Syntax for details. Here is a short summary of the JSON path syntax: - A JSON path starts with a scope: in MySQL's JSON document implementation, the scope of the path is always the document being operated on, represented as $, which is always implicitly assumed, so it can be skipped in most cases (except when, for example, the ** wildcard is used; see the discussion on wildcards below). For example, the path $.geography.Region is equivalent to geography.Region. - After the scope, a path consists of one or more path legs. A path leg leads from one level of the JSON tree down to the next, and consecutive paths are separated by a period (.). For example: myColl.find("geography.Continent = 'Africa'") finds all documents that have the value Africa for the field Continent under the field geography. - Elements in arrays are represented by [N], where N is an array index, which has to be a non-negative integer. ```java myColl.add({name:'John', favorNums: [1, 3, 5, 7, 9]}).execute(); myColl.find("favorNums[0] = 1").execute(); //Returns the document just added ``` - The wildcard tokens * and ** can be used in JSON paths as follows: - object.* represents the values of all members under the member object. For example, in the countryinfo collection in the sample world_x schema, geography.* represents all members under the object geography, and myColl.find("'Africa' in geography.*") returns all documents that have the value Africa in any of the members under geography. - array[*] represents the values of all elements in an array. For example: myColl.add({name:'John', favorNums: [1, 3, 5, 7, 9]}).execute(); myColl.add({name:'Jane', favorNums: [2, 4, 6, 8, 10]}).execute(); myColl.find("1 in favorNums[*]").execute(); //Returns the first document added above myColl.find("2 in favorNums[*]").execute(); //Returns the second document added above - \[prefix\]**\[suffix\] represents all paths under the document \[prefix\] that end with \[suffix\], regardless of the depth of the path. The following examples illustrate how ** can be used to return different results: ```javascript mySql> myColl.find().execute(); { "a": "bar", "b": { "b1": 6, "b2": 7, "b3": { "b1": 99, "b2": 98, "b3": { "b1": 999, "b2": 998 } } }, "_id": "000061313aa10000000000000001" } { "a": "baz", "b": { "b1": 1, "b2": 7 }, "_id": "000061313aa10000000000000002" } { "a": "bbr", "c": 37, "_id": "0000613247ed000000000000000001" } 3 documents in set (0.0007 sec) mySql> myColl.find("$**.b2").execute(); { "a": "bar", "b": { "b1": 6, "b2": 7, "b3": { "b1": 99, "b2": 98, "b3": { "b1": 999, "b2": 998 } } }, "_id": "000061313aa10000000000000001" } { "a": "baz", "b": { "b1": 1, "b2": 7 }, "_id": "000061313aa10000000000000002" } ``` The following requirements apply when using the ** wildcard: - **prefix** should be $ or an element that is a document itself. - **suffix** should be a path leg and is always required (that is, a path expression may not end in **). - A path expression may not contain the sequence ***. - **value** is a value to be compared to an element on the JSON-path. The % and _ wildcard characters can be used in value with the LIKE operator, just like in a MySQL WHERE clause. For example: ```javascript myColl.find("Name LIKE 'Austra%'") myColl.find("geography.Continent LIKE 'Asi_'") ``` - **operator**: The following operators can be used in a SearchConditionStr: OR (||), AND (&&), XOR, IS, NOT, BETWEEN, IN, LIKE, OVERLAPS, !, <, >, >=, <, <=, & | <<, >>, !, ~, and %. Here are some examples for using the operators: ```javascript myColl.find("Name = 'Australia'") myColl.find("demographics.Population >= 1000000") myColl.find("demographics.LifeExpectancy BETWEEN 50 AND 60") myColl.find("government.HeadOfState = 'Elizabeth II' AND geography.Region = 'Caribbean'") ``` If no operator and subsequent JSON path is supplied, find() returns all documents for which the JSON path supplied points to some non-null elements. For example: ```javascript myColl.find("demographics.Population").execute(); ``` Returns all documents that have a demographics.Population element: ```javascript { "GNP": 828, "_id": "000005de917d80000000000000000000", "Code": "ABW", "Name": "Aruba", "IndepYear": null, "geography": { "Region": "Caribbean", "Continent": "North America", } The code snippet demonstrates how to use the `Collection.find()` method in a MongoDB query. The query is tailored to find specific documents in a collection. The output shows the structure of the documents found, including metadata like `SurfaceArea`, government details (`HeadOfState`, `GovernmentForm`), and demographics (`Population`, `LifeExpectancy`). Additionally, the code includes a warning about evaluating a JSON value in SQL boolean context, suggesting the use of `JSON_VALUE RETURNING` to avoid such pitfalls. Use the `IN` operator in the `SearchConditionStr` to check for a value within all the members covered by a wildcard: ```javascript mysql-js> myColl.find("**.b1").execute(); { "a": "bar", "b": { "b1": 6, "b2": 7, "b3": { "b1": 99, "b2": 98, "b3": { "b1": 999, "b2": 998 } } }, "_id": "000061313aa10000000000000001" } { "a": "baz", "b": { "b1": 1, "b2": 7 }, "_id": "000061313aa100000000000000002" } 2 documents in set, 1 warning (0.0012 sec) ... mysql-js> myColl.find("99 IN **.b1").execute(); { "a": "bar", "b": { "b1": 6, "b2": 7, "b3": { "b1": 99, "b2": 98, "b3": { "b1": 999, "b2": 998 } } }, "_id": "000061313aa10000000000000001" } ``` This example showcases how to filter documents based on specific conditions within nested JSON structures. The `OVERLAPS` operator compares two JSON fragments and returns true (1) if the two fragments have any values in any key-value pair or array element in common. For example: ```javascript mysql-js> myColl.find("list").execute(); { "_id": "1", "list": [ 1, 4 ] } { "_id": "2", "list": [ 4, 7 ] } 2 documents in set, 1 warning (0.0010 sec) ``` ```javascript mysql-js> myColl.find("[1,2,3] OVERLAPS $.list") { "_id": "1", "list": [ 1, 4 ] } 1 document in set (0.0006 sec) ``` Several methods such as `fields()`, `sort()`, `skip()`, and `limit()` can be chained to the `find()` function to further refine the result. For example: ```javascript myColl.find("Name LIKE 'Austra%'") myColl.find("geography.Continent LIKE 'A%'") ``` Parameter binding using `bind()` is also supported. The following example illustrates the use of `bind()` with `find()`: ```javascript // Use the collection 'my_collection' var myColl = db.getCollection('my_collection'); // Find a single document that has a field 'name' that starts with 'L' var docs = myColl.find('name like :param').limit(1).bind('param', 'L%').execute(); print(docs.fetchOne()); // Get all documents with a field 'name' that starts with 'L' docs = myColl.find('name like :param').bind('param','L%').execute(); var myDoc; while (myDoc = docs.fetchOne()) { print(myDoc); } ``` See also `CollectionFindFunction` for the syntax of `find()` in EBNF. Collection.modify() Figure 4.1 Collection.modify() Syntax Diagram Collection.remove() The Collection.remove() function is used to remove documents in a collection, similar to the DELETE statement for a SQL database. It takes a search condition string (SearchConditionStr) as a parameter to specify the documents that should be removed from the collection (a detailed explanation of the SearchConditionStr can be found in Collection.find()). remove() returns an error if no search condition string is provided, or if an empty string is provided. All documents in the collection are removed if any expression that evaluates to true without matching any document (for example, "true" or "_id IS NOT NULL") is passed as the search condition string. The following methods can be chained to the remove() method to configure the deletion: - limit(int): Limits the number of documents to be deleted to int. - sort(sortCriteriaList): Sort the order in which documents are to be deleted according to sortCriteriaList, which is either a comma-separated list or an array of sortCriteria. Each sortCriteria consists of a component name and a search order (asc for ascending, or desc for descending). For example: - sort('name asc', 'age desc') - sort(['name asc', 'age desc']) The method is usually used in combination with the limit() method to determine which of the documents matched by the search condition string are to be deleted. Parameter binding using bind() is also supported, and the execute() function triggers the actual execution of the remove operation. The following example shows how to use the Collection.remove() function. It assumes some documents have been added to the collection as illustrated by the code example in Collection.add(): --- Collection.modify() 4.4 Indexing Collections To make large collections of documents more efficient to navigate you can create an index based on one or more fields found in the documents in the collection. This section describes how to index a collection. Creating an Index Collection indexes are ordinary MySQL indexes on virtual columns that extract data from the documents in the collection. Because MySQL cannot index JSON values directly, to enable indexing of a collection, you provide a JSON document that specifies the document's fields to be used by the index. You pass the JSON document defining the index as the `IndexDefinition` parameter to the `Collection.createIndex(name, IndexDefinition)` method. This generic example (actual syntax might vary for different programming languages) shows how to create a mandatory integer type index based on the field `count`: ``` myCollection.createIndex("count", {fields: [{field: ".count", type: "INT", required:true}]}) ``` This example shows how to create an index based on a text field: a zip code in this case. For a text field, you must specify a prefix length for the index, as required by MySQL Server: ``` myCollection.createIndex("zip", {fields: [{field: ".zip", type: "TEXT(10)"}]}) ``` See Defining an Index for information on the format of `IndexDefinition` and on the supported field types for indexing. The `Collection.createIndex()` method fails with an error if an index with the same name already exists or if the index definition is not correctly formed. The name parameter is required and must be a valid index name as accepted by the SQL statement `CREATE INDEX`. To remove an existing index use the `collection.dropIndex(string name)` method. This would delete the index with the passed name, and the operation silently succeeds if the named index does not exist. The indexes of a collection are stored as virtual columns. To verify a created index use the `SHOW INDEX` statement. For example to use this SQL from MySQL Shell: ``` session.runSql('SHOW INDEX FROM mySchema.myCollection'); ``` Defining an Index To create an index based on the documents in a collection you need to create an `IndexDefinition` JSON document. This section explains the valid fields you can use in such a JSON document to define an index. To define a document field to index a collection on, the type of that field must be uniform across the whole collection. In other words, the type must be consistent. The JSON document used for defining an index, such as `{fields: [{field: ".username", type: "TEXT"}]}, can contain the following: Defining an Index - **fields**: an array of at least one `IndexField` object, each of which describes a JSON document field to be included in the index. A single `IndexField` description consists of the following fields: - **field**: a string with the full document path to the document member or field to be indexed - **type**: a string for one of the supported column types to map the field to (see Field Data Types). For numeric types, the optional `UNSIGNED` keyword can follow. For the `TEXT` type you must define the length to consider for indexing (the prefix length). - **required**: an optional boolean that should be set to `true` if the field is required to exist in the document. Defaults to `false` for all types except `GEOJSON`, which defaults to `true`. - **options**: an optional integer that is used as a special option flag when decoding `GEOJSON` data (see the description for `ST_GeomFromGeoJSON()` for details). - **srid**: an optional integer to be used as the `srid` value when decoding `GEOJSON` data (see the description for `ST_GeomFromGeoJSON()` for details). - **array**: (for MySQL 8.0.17 and later) an optional boolean that is set to `true` if the field contains arrays. The default value is `false`. See Indexing Array Fields for details. Important For MySQL 8.0.16 and earlier, fields that are JSON arrays are not supported in the index; specifying a field that contains array data does not generate an error from the server, but the index does not function correctly. - **type**: an optional string that defines the type of index. Value is one of `INDEX` or `SPATIAL`. The default is `INDEX` and can be omitted. Including any other fields in an `IndexDefinition` or `IndexField` JSON document which is not described above causes `collection.createIndex()` to fail with an error. If index type is not specified or is set to `INDEX` then the resulting index is created in the same way as it would be created by issuing `CREATE INDEX`. If index type is set to `SPATIAL` then the created index is the same as it would be created by issuing `CREATE INDEX` with the `SPATIAL` keyword, see SPATIAL Index Optimization and Creating Spatial Indexes. For example: ```javascript myCollection.createIndex('myIndex', { // fields: [{field: '$.myGeoJsonField', type: 'GEOJSON', required: true}], type: 'SPATIAL' }) ``` Important When using the `SPATIAL` type of index the `required` field cannot be set to `false` in `IndexField` entries. This is an example to create an index based on multiple fields: ```javascript myCollection.createIndex('myIndex', { // fields: [{field: '$.myField', type: 'TEXT'}, {field: '$.myField2', type: 'TEXT(10)'}, {field: '$.myField3', type: 'INT'}] }) ``` The values of indexed fields are converted from JSON to the type specified in the `IndexField` description using standard MySQL type conversions (see Type Conversion in Expression Evaluation), except for the `GEOJSON` type, which uses the `ST_GeomFromGeoJSON()` function for conversion. That means when using a numeric type in an `IndexField` description, an actual field value that is non-numeric is converted to 0. The options and srid fields in IndexField can only be present if type is set to GEOJSON. If present, they are used as parameters for ST_GeomFromGeoJSON() when converting GEOJSON data into MySQL native GEOMETRY values. Field Data Types The following data types are supported for document fields. Type names are case-insensitive when used in the type field. • INT [UNSIGNED] • TINYINT [UNSIGNED] • SMALLINT [UNSIGNED] • MEDIUMINT [UNSIGNED] • INTEGER [UNSIGNED] • BIGINT [UNSIGNED] • REAL [UNSIGNED] • FLOAT [UNSIGNED] • DOUBLE [UNSIGNED] • DECIMAL [UNSIGNED] • NUMERIC [UNSIGNED] • DATE • TIME • TIMESTAMP • DATETIME • TEXT(length) • GEOJSON (extra options: options, srid) Indexing Array Fields For MySQL 8.0.17 and later, X DevAPI supports creating indexes based on array fields by setting the boolean array field in the IndexField description to true. For example, to create an index on the emails array field: ```javascript collection.createIndex("emails_idx", // {fields: ["$.emails", "type":"CHAR(128)", "array": true}])); ``` The following restrictions apply to creating indexes based on arrays: • For each index, only one indexed field can be an array • Data types for which index on arrays can be created: • Numeric types: INTEGER [UNSIGNED] (INT is NOT supported) Single Document Operations - Fixed-point types: `DECIMAL(m, n)` (the precision and scale values are mandatory) - Date and time types: `DATE`, `TIME`, and `DATETIME` - String types: `CHAR(n)` and `BINARY(n)`; the character or byte length `n` is mandatory (`TEXT` is NOT supported) ### 4.5 Single Document Operations The CRUD commands described at Section 4.3, “Collection CRUD Function Overview” all act on a group of documents in a collection that match a filter. X DevAPI also provides the following operations, which work on single documents that are identified by their document IDs: - `Collection.getOne(string id)` returns the document with the given `id`. This is a shortcut for `Collection.find("_id = :id").bind("id", id).execute().fetchOne()`. - `Collection.replaceOne(string id, Document doc)` updates or replaces the document identified by `id`, if it exists, with the provided document. - `Collection.addOrReplaceOne(string id, Document doc)` adds the given document; however, if the `id` or any other field that has a unique index on it already exists in the collection, the operation updates the matching document instead. - `Collection.removeOne(string id)` removes the document with the given `id`. This is a shortcut for `Collection.remove("_id = :id").bind("id", id).execute()`. Using these operations you can reference a document by its ID (see Section 5.2, “Working with Document IDs”), making operations on single documents simpler by following a "load, modify, and save" pattern such as the following: ```javascript doc = collection.getOne(id); // Load document of the specified id into a temporary document called doc doc["address"] = "123 Long Street"; //Modify the "address" field of doc collection.replaceOne(id, doc); // Save doc into the document with the specified id ``` ### Syntax of Single Document Operations The syntax of the single document operations is as follows: - `Document getOne(string id)`, where `id` is the document ID of the document to be retrieved. This operation returns the document, or `NULL` if no match is found. Searches for the document that has the given `id` and returns it. - `Result replaceOne(string id, Document doc)`, where `id` is the document ID of the document to be replaced and `doc` is the new document, which can contain expressions. If `doc` contains an `_id` value, it is ignored. The operation returns a `Result` object, which indicates the number of affected documents (1 or 0, if none). Takes in a document object which replaces the matching document. If no matches are found, the function returns normally with no changes being made. - `Result addOrReplaceOne(string id, Document doc)`, where `id` is the document ID of the document to be replaced and `doc` is the new document, which can contain expressions. If `doc` contains an `_id` value, it is ignored. This operation returns a `Result` object, which indicates the number of affected documents (1 or 0, if none). Adds the document to the collection. If `doc` has a value for `_id` and it does not match the given `id` then an error is generated. If the collection has a document with the given document ID then the collection is checked for any document that conflicts with unique keys from `doc` and where the document ID of conflicting documents is not `id` then an error is generated. Otherwise the existing document in the collection is replaced by `doc`. If the collection has any document that conflicts with unique keys from `doc` then an error is generated. Otherwise `doc` is added to collection. - **Result removeOne(string id)**, where `id` is the document ID of the document to be removed. This operation returns a **Result** object, which indicates the number of removed documents (1 or 0, if none). **Important** These operations accept an explicit `id` to ensure that any changes being made by the operation are applied to the intended document. In many scenarios the document `doc` could come from an untrusted user, who could potentially change the `id` in the document and thus replace other documents than the application expects. To mitigate this risk, you should transfer the explicit document `id` through a secure channel. ## 4.6 JSON Schema Validation Starting from version 8.0.21, collections can be configured to verify documents against a JSON schema. This enables you to require that documents have a certain structure before they can be inserted or updated in a collection. You specify a JSON schema as described at [http://json-schema.org](http://json-schema.org). Schema validation is performed by the server starting from version 8.0.19, which returns an error message if a document in a collection does not validate against the assigned JSON schema. For more information on JSON schema validation in MySQL, see [JSON Schema Validation Functions](#). This section describes how to configure a collection to validate documents against a JSON schema. To enable or modify JSON schema validation, you supply to a collection a `validation` JSON object like the following: ```json { validation: { level: "off|strict", schema: "json-schema" } } ``` Here, `validation` is a JSON object that contains the keys you can use to configure JSON schema validation. The first key is `level`, which can take the value `strict` or `off`. The second key, `schema`, is a JSON schema, as defined at [http://json-schema.org](http://json-schema.org). If the `level` key is set to `strict`, documents are validated against the `json-schema` when they are added to the collection or, if they are already in the collection, when they are updated by some operations. If a document does not validate, the server generates an error and the operation fails. If the `level` key is set to `off`, documents are not validated against the `json-schema`. ### Creating a Validated Collection To enable JSON schema validation when you create a new collection, supply a `validation` JSON object as described above. For example, to create a collection that holds longitude and latitude values and require validating those values as numbers: ```javascript var coll = schema.createCollection("longlang", { validation: { level: "strict", schema: { "id": "http://json-schema.org/geo", "$schema": "http://json-schema.org/draft-06/schema#", "description": "A geographical coordinate", "type": "object", } } }); ``` Modifying Collection Validation You can modify a collection to control the JSON schema validation of documents. For example, you can enable or disable validation, or change the JSON schema that documents are validated against. In order to modify the JSON schema validation of a collection, supply a validation JSON object when calling the `Collection.modify()` method. For example, to modify a collection to disable JSON schema validation, the validation object would be: ```json { "validation": { "level": "off" } } ``` When modifying the JSON schema validation, you can supply the `level` option alone to change just the level of schema validation. For example, pass the JSON object shown above to disable JSON schema validation. This makes no change to the JSON schema previously specified and does not remove the JSON schema from the collection. Alternatively, you can modify the schema only by passing just a new JSON schema object. Chapter 5 Working with Documents Table of Contents 5.1 Creating Documents ................................................................. 29 5.2 Working with Document IDs ...................................................... 29 5.3 Understanding Document IDs .................................................... 31 5.1 Creating Documents Once a collection has been created, it can store JSON documents. You store documents by passing a JSON data structure to the `Collection.add()` function. Some languages have direct support for JSON data, others have an equivalent syntax to represent that data. MySQL Connectors that implement X DevAPI aim to implement support for all JSON methods that are native to the Connectors' specific languages. In addition, in some MySQL Connectors the generic `DbDoc` objects can be used. The most convenient way to create them is by calling the `Collection.newDoc()`. `DbDoc` is a data type to represent JSON documents and how it is implemented is not defined by X DevAPI. Languages implementing X DevAPI are free to follow an object-oriented approach with getter and setter methods, or use a C struct style with public members. For strictly-typed languages it is possible to create class files based on the document structure definition of collections. MySQL Shell can be used to create those files. <table> <thead> <tr> <th>Document Objects</th> <th>Supported languages</th> <th>Advantages</th> </tr> </thead> <tbody> <tr> <td>Native JSON</td> <td>Scripting languages (JavaScript, Python)</td> <td>Easy to use</td> </tr> <tr> <td>JSON equivalent syntax</td> <td>C# (Anonymous Types, ExpandoObject)</td> <td>Easy to use</td> </tr> <tr> <td>DbDoc</td> <td>All languages</td> <td>Unified across languages</td> </tr> <tr> <td>Generated Doc Classes</td> <td>Strictly typed languages (C#)</td> <td>Natural to use</td> </tr> </tbody> </table> The following example shows the different methods of inserting documents into a collection. ```javascript // Create a new collection 'my_collection' var myColl = db.createCollection('my_collection'); // Insert JSON data directly myColl.add({_id: '8901', name: 'Mats', age: 21}).execute(); // Inserting several docs at once myColl.add([ {_id: '8902', name: 'Lotte', age: 24}, {_id: '8903', name: 'Vera', age: 39} ]).execute(); ``` 5.2 Working with Document IDs This section describes what a document ID is and how to work with it. Every document has a unique identifier called the document ID, which can be thought of as the equivalent of a table's primary key. The document ID value is usually automatically generated by the server when the document is added, but can also be manually assigned. The assigned document ID is returned in the `generatedIds` property of the `Result` (`AddResult` for Connector/J) object for the `collection.add()` operation and can be accessed using the `getGeneratedIds()` method. See Section 5.3, “Understanding Document IDs” for more background information on document IDs. The following example in JavaScript code shows adding a document to a collection, retrieving the added document's IDs and testing that duplicate IDs cannot be added. ```javascript mysql-js > var result = mycollection.add({test:'demo01'}).execute() mysql-js > print(result.generatedIds) [ "00006075f6810000000000000006" ] mysql-js > var result = mycollection.add({test:'demo02'}).add({test:'demo03'}).execute() mysql-js > print(result.generatedIds) [ "00006075f6810000000000000007", "00006075f6810000000000000008" ] mysql-js > mycollection.find() { "_id": "00006075f6810000000000000006", "test": "demo01" } { "_id": "00006075f6810000000000000007", "test": "demo02" } { "_id": "00006075f6810000000000000008", "test": "demo03" } 3 documents in set (0.0102 sec) mysql-js > var result = mycollection.add({_id:'00006075f6810000000000000008', test:'demo04'}).execute() Document contains a field value that is not unique but required to be (MySQL Error 5116) ``` As shown in the example above, the document ID is stored in the `_id` field of a document. The document ID is a `VARBINARY()` with a maximum length of 32 characters. If an `_id` is provided when a document is created, it is honored; if no `_id` is provided, one is automatically assigned to the document. The following example illustrates how the `_id` value can either be provided or autogenerated. It is assumed that the `test` schema exists and is assigned to the variable `db`, that the collection `my_collection` exists and that `custom_id` is unique. ```javascript // If the _id is provided, it will be honored var result = myColl.add( { _id: 'custom_id', a : 1 } ).execute(); var document = myColl.find("a = 1").execute().fetchOne(); print("User Provided Id:", document._id); // If the _id is not provided, one will be automatically assigned result = myColl.add( { b: 2 } ).execute(); print("Autogenerated Id:", result.getGeneratedIds()[0]); ``` Some documents have a natural unique key. For example, a collection that holds a list of books is likely to include the International Standard Book Number (ISBN) for each document that represents a book. The ISBN is a string with a length of 13 characters, which is well within the length limit of 32 characters for the `_id` field. ```javascript // using a book's unique ISBN as the object ID myColl.add( { _id: "978-1449374020", title: "MySQL Cookbook: Solutions for Database Developers and Administrators" }); ``` Use `find()` to fetch the newly inserted book from the collection by its document ID. ```javascript var book = myColl.find('_id = "978-1449374020"').execute(); ``` Currently, X DevAPI does not support using any document field other than the implicit `_id` as the document ID—there is no way to define another key to perform the same function. ## 5.3 Understanding Document IDs This section describes in detail how document IDs are generated and how to interpret them. X DevAPI relies on server-based document ID generation, added in MySQL version 8.0.11, which results in sequentially increasing document IDs across all clients. *InnoDB* uses the document ID as a primary key, resulting in efficient page splits and tree reorganizations. This section describes the properties and format of the automatically generated document IDs. ### Document ID Properties The `_id` field of a document behaves in the same way as any other fields of the document during queries, except that its value cannot be changed once it has been inserted to the collection. The `_id` field is used as the primary key of the collection. It is possible to override the automatic generation of document IDs by manually including an ID in an inserted document. **Important** X Plugin is not aware of the data inserted into the collection, including any manual document IDs you use. When using manual document IDs, you must ensure that they do not clash with any IDs that might ever be generated automatically by the server (see Document ID Generation for details), in order to avoid any errors due to primary key duplication. Whenever an `_id` field value is not present in an inserted document, the server generates an `_id` value. The generated `_id` value used for a document is returned to the client as part of the `Result` object of the `add()` operation. If you are using X DevAPI on an InnoDB Cluster, the automatically generated `_id` must be unique within the whole cluster. By setting the `mysqlx_document_id_unique_prefix` to a unique value per cluster instance, you can ensure document IDs are unique across all the instances. The `_id` field must be sequential (always incrementing) for optimal InnoDB insertion performance (at least within a single server). The sequential nature of `_id` values is maintained across server restarts. In a multi-primary Group Replication or InnoDB Cluster environment, the generated `_id` values of a table are unique across instances to avoid primary key conflicts and minimize transaction certification. ### Document ID Generation This section describes how document IDs are formatted. The format of automatically generated document ID is: <table> <thead> <tr> <th>unique_prefix</th> <th>start_timestamp</th> <th>serial</th> </tr> </thead> <tbody> <tr> <td>4 bytes</td> <td>8 bytes</td> <td>16 bytes</td> </tr> </tbody> </table> Where: • `unique_prefix` is a value assigned by InnoDB Cluster to the instance, which is used to make the document ID unique across all instances from the same cluster. The range of `unique_prefix` is from 0 to $2^{16} - 1$, which is hex encoded. Default value is 0, if it is neither set by InnoDB Cluster nor by the `mysqlx_document_id_unique_prefix` system variable. • `start_timestamp` is the time stamp of the startup time of the server instance, which is hex encoded. In the unlikely event that the value of `serial` overflows, the `start_timestamp` is incremented by 1 and the `serial` value then restarts at 0. • `serial` is a per-instance automatically incremented integer serial number value, which is hex encoded and has a range of 0 to $2^{64} - 1$. The initial value of `serial` is set to the `auto_increment_offset` system variable, and the increment of the value is set by the `auto_increment_increment` system variable. This document ID format ensures that: • The primary key value monotonically increments for inserts originating from a single server instance, although the interval between values is not uniform within a table. • When using multi-primary Group Replication or InnoDB Cluster, inserts to the same table from different instances do not have conflicting primary key values, as long as the instances have the `auto_increment_offset` and the `auto_increment_increment` system variables configured properly (see descriptions of the variables for details). Chapter 6 Working with Relational Tables Table of Contents 6.1 Syntax of the SQL CRUD Functions ................................................................. 33 The X DevAPI SQL CRUD functions allow you to work with relational tables in manners similar to using traditional SQL statements. The following code sample shows how to use the add() and select() methods of the X DevAPI SQL CRUD functions, which are similar to running INSERT and SELECT statements on a table with a SQL client. Compare this with the examples found in Section 4.3, “Collection CRUD Function Overview” to see the differences and similarities between the CRUD functions for tables and collections in the X DevAPI. ```javascript // Working with Relational Tables var mysqlx = require('mysqlx'); // Connect to server using a connection URL var mySession = mysqlx.getSession({ host: 'localhost', port: 33060, user: 'user', password: 'password' }) var myDb = mySession.getSchema('test'); // Accessing an existing table var myTable = myDb.getTable('my_table'); // Insert SQL Table data myTable.insert(['name', 'birthday', 'age']). values('Laurie', mysqlx.dateValue(2000, 5, 27), 19).execute(); // Find a row in the SQL Table var myResult = myTable.select(['_id', 'name', 'birthday']). where('name like :name AND age < :age'). bind('name', 'L%').bind('age', 30).execute(); // Print result print(myResult.fetchOne()); ``` 6.1 Syntax of the SQL CRUD Functions The following SQL CRUD functions are available in X DevAPI. **Table.insert()** The `Table.insert()` method works like an `INSERT` statement in SQL. It is used to store data in a relational table in the database. It is executed by the `execute()` function. The following example shows how to use the `Table.insert()` function. The example assumes that the `test` schema exists and is assigned to the variable `db`, and that an empty table called `my_table` exists. ```javascript // Accessing an existing table var myTable = db.getTable('my_table'); // Insert a row of data. myTable.insert(['id', 'name']). values(1, 'Imani'). values(2, 'Adam'). ``` Table.select() The `Table.select()` method works like a SELECT statement in SQL. Notice that `Table.select()` and `collection.find()` use different methods for sorting results: `Table.select()` uses the method `orderBy()`, reminiscent of the ORDER BY keyword in SQL, while the `sort()` method is used to sort the results returned by `Collection.find()`. Table.update() The `Table.update()` method works like an UPDATE statement in SQL. **Table.delete()** The `Table.delete()` method works like a `DELETE` statement in SQL. **Figure 6.4 Table.delete() Syntax Diagram** ![Syntax Diagram](image) Chapter 7 Working with Relational Tables and Documents Table of Contents 7.1 Collections as Relational Tables ................................................................. 37 After seeing how to work with documents and how to work with relational tables, this section explains how to combine the two and work with both at the same time. It can be beneficial to use documents for very specific tasks inside an application and rely on relational tables for other tasks. Or a very simple document only application can outgrow the document model and incrementally integrate or move to a more powerful relational database. This way the advantages of both documents and relational tables can be combined. SQL tables contribute strictly typed value semantics, predictable and optimized storage. Documents contribute type flexibility, schema flexibility and non-scalar types. 7.1 Collections as Relational Tables Applications that seek to store standard SQL columns with Documents can cast a collection to a table. In this case a collection can be fetched as a Table object with the Schema.getCollectionAsTable() function. From that moment on it is treated as a regular table. Document values can be accessed in SQL CRUD operations using the following syntax: ``` doc->'$.field' ``` `doc->'$.field'` is used to access the document top level fields. More complex paths can be specified as well. ``` doc->'$.some.field.like[3].this' ``` Once a collection has been fetched as a table with the Schema.getCollectionAsTable() function, all SQL CRUD operations can be used. Using the syntax for document access, you can select data from the Documents of the Collection and the extra SQL columns. The following example shows how to insert a JSON document string into the `doc` field. ```javascript // Get the customers collection as a table var customers = db.getCollectionAsTable('customers'); customers.insert('doc').values({"_id": "001", "name": "Ana", "last_name": "Silva"'}).execute(); // Now do a find operation to retrieve the inserted document var result = customers.select(['doc->'$.name', 'doc->'$.last_name']).where("doc->'$._id' = '001'").execute(); var record = result.fetchOne(); print ("Name : " + record[0]); print ("Last Name : " + record[1]); ``` Chapter 8 Statement Execution Table of Contents 8.1 Transaction Handling ............................................................................................................ 39 8.1.1 Processing Warnings .................................................................................................... 40 8.1.2 Error Handling ............................................................................................................. 41 8.2 Working with Savepoints ..................................................................................................... 42 8.3 Working with Locking ......................................................................................................... 43 8.4 Working with Prepared Statements ..................................................................................... 44 This section explains statement execution, with information on how to handle transactions and errors. 8.1 Transaction Handling Transactions can be used to group operations into an atomic unit. Either all operations of a transaction succeed when they are committed, or none. It is possible to roll back a transaction as long as it has not been committed. Transactions can be started in a session using the `startTransaction()` method, committed with `commitTransaction()` and cancelled or rolled back with `rollbackTransaction()`. This is illustrated in the following example. The example assumes that the `test` schema exists and that the collection `my_collection` does not exist. ```javascript var mysqlx = require('mysqlx'); // Connect to server var session = mysqlx.getSession( { host: 'localhost', port: 33060, user: 'user', password: 'password' } ); // Get the Schema test var db = session.getSchema('test'); // Create a new collection var myColl = db.createCollection('my_collection'); // Start a transaction session.startTransaction(); try { myColl.add({name: 'Rohit', age: 18, height: 1.76}).execute(); myColl.add({name: 'Misaki', age: 24, height: 1.65}).execute(); myColl.add({name: 'Leon', age: 39, height: 1.9}).execute(); // Commit the transaction if everything went well session.commit(); print('Data inserted successfully.'); } catch (err) { // Rollback the transaction in case of an error session.rollback(); // Printing the error message print('Data could not be inserted: ' + err.message); } ``` 8.1.1 Processing Warnings Similar to the execution of single statements committing or rolling back a transaction can also trigger warnings. To be able to process these warnings the replied result object of `Session.commit()`; or `Session.rollback()`; needs to be checked. This is shown in the following example. The example assumes that the test schema exists and that the collection `my_collection` does not exist. ```javascript var mysqlx = require('mysqlx'); // Connect to server var mySession = mysqlx.getSession( { host: 'localhost', port: 33060, user: 'user', password: 'password' }); // Get the Schema test var myDb = mySession.getSchema('test'); // Create a new collection var myColl = myDb.createCollection('my_collection'); // Start a transaction mySession.startTransaction(); try { myColl.add({ 'name': 'Rohit', 'age': 18, 'height': 1.76 }).execute(); myColl.add({ 'name': 'Misaki', 'age': 24, 'height': 1.65 }).execute(); myColl.add({ 'name': 'Leon', 'age': 39, 'height': 1.9 }).execute(); // Commit the transaction if everything went well var reply = mySession.commit(); // handle warnings if (reply.warningCount){ var warnings = reply.getWarnings(); for (index in warnings){ print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n'); } } print ('Data inserted successfully.'); } catch(err) { // Rollback the transaction in case of an error reply = mySession.rollback(); // handle warnings if (reply.warningCount){ var warnings = reply.getWarnings(); for (index in warnings){ var warning = warnings[index]; print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n'); } } // Printing the error message print ('Data could not be inserted: ' + err.message); } ``` By default all warnings are sent from the server to the client. If an operation is known to generate many warnings and the warnings are of no value to the application then sending the warnings can be 8.1.2 Error Handling When writing scripts for MySQL Shell you can often simply rely on the exception handling done by MySQL Shell. For all other languages either proper exception handling is required to catch errors or the traditional error handling pattern needs to be used if the language does not support exceptions. The default error handling can be changed by creating a custom SessionContext and passing it to the mysqlx.getSession() function. This enables switching from exceptions to result based error checking. The following example shows how to perform proper error handling. The example assumes that the test schema exists and that the collection my_collection exists. 8.2 Working with Savepoints X DevAPI supports savepoints, which enable you to set a named point within a transaction that you can revert to. By setting savepoints within a transaction, you can later use the rollback functionality to undo any statements issued after setting the savepoint. Savepoints can be released if you no longer require them. This section documents how to work with savepoints in X DevAPI. See SAVEPOINT for background information. Setting a Savepoint Savepoints are identified by a string name. The string can contain any character allowed for an identifier. To create a savepoint, use the `session.setSavepoint()` operation, which maps to the SQL statement `SAVEPOINT name;`. If you do not specify a `name`, one is automatically generated. For example by issuing: ```javascript session.setSavepoint() ``` a transaction savepoint is created with an automatically generated name and a string is returned with the name of the savepoint. This name can be used with the `session.rollbackTo()` or `session.releaseSavepoint()` operations. The `session.setSavepoint()` operation can be called multiple times within a session and each time a unique savepoint name is generated. It is also possible to manually define the name of the savepoint by passing in a string `name`. For example issuing: ```javascript session.setSavepoint('name') ``` results in a transaction savepoint with the specified `name`, which is returned by the operation as a string. The `session.setSavepoint('name')` operation can be called multiple times in this way, and if the `name` has already been used for a savepoint then the previous savepoint is is deleted and a new one is set. Rolling Back to a Savepoint When a session has transaction savepoints, you can undo any subsequent transactions using the `session.rollbackTo()` operation, which maps to the `ROLLBACK TO name` statement. For example, issuing: ```javascript session.rollbackTo('name') ``` rolls back to the transaction savepoint `name`. This operation succeeds as long as the given savepoint has not been released. Rolling back to a savepoint which was created prior to other savepoints results in the subsequent savepoints being either released or rolled back. For example: Releasing a Savepoint To cancel a savepoint, for example when it is no longer needed, use `releaseSavepoint()` and pass in the name of the savepoint you want to release. For example, issuing: ```javascript session.releaseSavepoint('name') ``` releases the savepoint `name`. Savepoints and Implicit Transaction Behavior The exact behavior of savepoints is defined by the server, and specifically how autocommit is configured. See autocommit, Commit, and Rollback. For example, consider the following statements with no explicit `BEGIN`, `session.startTransaction()` or similar call: ```javascript session.setSavepoint('testsavepoint'); session.releaseSavepoint('testsavepoint'); ``` If autocommit mode is enabled on the server, these statements result in an error because the savepoint named `testsavepoint` does not exist. This is because the call to `session.setSavepoint()` creates a transaction, then the savepoint and directly commits it. The result is that savepoint does not exist by the time the call to `releaseSavepoint()` is issued, which is instead in its own transaction. In this case, for the savepoint to survive you need to start an explicit transaction block first. 8.3 Working with Locking X DevAPI supports MySQL locking through the `lockShared()` and `lockExclusive()` methods for the `Collection.find()` and `Table.select()` methods. This enables you to control row locking to ensure safe, transactional document updates on collections and to avoid concurrency problems, for example when using the `modify()` method. This section describes how to use the `lockShared()` and `lockExclusive()` methods for both the `Collection.find()` and `Table.select()` methods. For more background information on locking, see Locking Reads. The `lockShared()` and `lockExclusive()` methods have the following properties, whether they are used with a Collection or a Table. - Multiple calls to the lock methods are permitted. If a locking statement executes while a different transaction holds the same lock, it blocks until the other transaction releases it. If multiple calls to the lock methods are made, the last called lock method takes precedence. In other words `find().lockShared().lockExclusive()` is equivalent to `find().lockExclusive()`. - `lockShared()` has the same semantics as `SELECT ... LOCK IN SHARE MODE`. Sets a shared mode lock on any rows that are read. Other sessions can read the rows, but cannot modify them until your transaction commits. If any of these rows were changed by another transaction that has not yet committed, your query waits until that transaction ends and then uses the latest values. - `lockExclusive()` has the same semantics as `SELECT ... FOR UPDATE`. For any index records the search encounters, it locks the rows and any associated index entries, in the same way as if you issued an `UPDATE` statement for those rows. Other transactions are blocked from updating those rows, from doing `SELECT ... LOCK IN SHARE MODE`, or from reading the data in certain transaction isolation levels. Consistent reads ignore any locks set on the records that exist in the read view. Old versions of a record cannot be locked; they are reconstructed by applying undo logs on an in-memory copy of the record. - Locks are held for as long as the transaction which they were acquired in exists. They are immediately released after the statement finishes unless a transaction is open or autocommit mode is turned off. Both locking methods support the `NOWAIT` and `SKIP LOCKED` InnoDB locking modes. For more information see Locking Read Concurrency with NOWAIT and SKIP LOCKED. To use these locking modes with the locking methods, pass in one of the following: - `NOWAIT` - if the function encounters a row lock it aborts and generates an `ER_LOCK_NOWAIT` error - `SKIP_LOCKED` - if the function encounters a row lock it skips the row and continues - `DEFAULT` - if the function encounters a row lock it waits until there is no lock. The equivalent of calling the lock method without a mode. ### Locking considerations When working with locking modes note the following: - `autocommit` mode means that there is always a transaction open, which is committed automatically when an SQL statement executes. - By default sessions are in autocommit mode. - You disable autocommit mode implicitly when you call `startTransaction()`. - When in autocommit mode, if a lock is acquired, it is released after the statement finishes. This could lead you to conclude that the locks were not acquired, but that is not the case. - Similarly, if you try to acquire a lock that is already owned by someone else, the statement blocks until the other lock is released. ### 8.4 Working with Prepared Statements *Implemented in MySQL 8.0.16 and later:* X DevAPI improves performance for each CRUD statement that is executed repeatedly by using a server-side prepared statement for its second and subsequent executions. This happens internally—applications do not need to do anything extra to utilize the feature, as long as the same operation object is reused. When a statement is executed for a second time with changes only in data values or in values that refine the execution results (for example, different `offset()` or `limit()` values), the server prepares the statement for subsequent executions, so that there is no need to reparse the statement when it is being run again. New values for re-executions of the prepared statement are provided with parameter binding. When the statement is modified by chaining to it a method that refines the result (for example, `sort()`, `skip()`, `limit()`, or `offset()`), the statement is reprepared. The following pseudocode and the comments on them demonstrate the feature: Working with Prepared Statements ```javascript var f = coll.find("field = :field"); f.bind("field", 1).execute(); // Normal execution f.bind("field", 2).execute(); // Same statement executed with a different parameter value triggers statement preparation f.bind("field", 3).execute(); // Prepared statement executed with a new value f.bind("field", 3).limit(10).execute(); // Statement reprepared as it is modified with limit() f.bind("field", 4).limit(20).execute(); // Reprepared statement executed with new parameters ``` Notice that to take advantage of the feature, the same operation object must be reused in the repetitions of the statement. Look at this example: ```javascript for (i=0; i<100; ++i) { collection.find().execute(); } ``` This loop cannot take advantage of the prepared statement feature, because the operation object of `collection.find()` is recreated at each iteration of the `for` loop. Now, look at this example: ```javascript for (i=0; i<100; ++i) { var op = collection.find() op.execute(); } ``` The repeated statement is prepared once and then reused, because the same operation object of `collection.find()` is re-executed for each iteration of the `for` loop. Prepared statements are part of a `Session`. When a `Client` resets the `Session` (by using, for example, `Mysqlx.Session.Reset`), the prepared statements are dropped. Chapter 9 Working with Result Sets Table of Contents 9.1 Result Set Classes .................................................................................................................. 47 9.2 Working with AUTO_INCREMENT Values .................................................................................. 48 9.3 Working with Data Sets .......................................................................................................... 48 9.4 Fetching All Data Items at Once ............................................................................................. 49 9.5 Working with SQL Result Sets ............................................................................................... 50 9.6 Working with Metadata ........................................................................................................... 52 9.7 Support for Language Native Iterators ................................................................................... 52 This section explains how to work with the results of processing. 9.1 Result Set Classes All database operations return a result. The type of result returned depends on the operation which was executed. The different types of results returned are outlined in the following table. <table> <thead> <tr> <th>Result Class</th> <th>Returned By</th> <th>Provides</th> </tr> </thead> <tbody> <tr> <td>Result</td> <td>add().execute(),</td> <td>affectedRows, lastInsertId,</td> </tr> <tr> <td></td> <td>insert().execute(),...</td> <td>warnings</td> </tr> <tr> <td>SqlResult</td> <td>session.sql()</td> <td>affectedRows, lastInsertId,</td> </tr> <tr> <td></td> <td></td> <td>warnings, fetched data sets</td> </tr> <tr> <td>DocResult</td> <td>find().execute()</td> <td>fetched data set</td> </tr> <tr> <td>RowResult</td> <td>select.execute()</td> <td>fetched data set</td> </tr> </tbody> </table> The following class diagram gives a basic overview of the result handling. 9.2 Working with **AUTO_INCREMENT** Values **AUTO_INCREMENT** columns can be used in MySQL for generating primary key or **id** values, but are not limited to these uses. This section explains how to retrieve **AUTO_INCREMENT** values when adding rows using X DevAPI. For more background information, see Using **AUTO_INCREMENT**. X DevAPI provides the `getAutoIncrementValue()` method to return the first **AUTO_INCREMENT** column value that was successfully inserted by the operation, taken from the return value of `table.insert()`. In the following example it is assumed that the table contains a column for which the **AUTO_INCREMENT** attribute is set: ```java res = myTable.insert(['name']).values('Mats').values('Otto').execute(); print(res.getAutoIncrementValue()); ``` This `table.insert()` operation inserted multiple rows. `getAutoIncrementValue()` returns the **AUTO_INCREMENT** column value generated for the first inserted row only, so in this example, for the row containing “Mats”. The reason for this is to make it possible to reproduce easily the same operation against some other server. 9.3 Working with Data Sets Operations that fetch data items return a data set as opposed to operations that modify data and return a result set. Data items can be read from the database using `Collection.find()`, `Table.select()` and `Session.sql()`. All three methods return data sets which encapsulate data... items. `Collection.find()` returns a data set with documents and `Table.select()` respectively `Session.sql()` return a data set with rows. All data sets implement a unified way of iterating their data items. The unified syntax supports fetching items one by one using `fetchOne()` or retrieving a list of all items using `fetchAll()`. `fetchOne()` and `fetchAll()` follow forward-only iteration semantics. Connectors implementing the X DevAPI can offer more advanced iteration patterns on top to match common native language patterns. The following example shows how to access the documents returned by a `Collection.find()` operation by using `fetchOne()` to loop over all documents. The first call to `fetchOne()` returns the first document found. All subsequent calls increment the internal data item iterator cursor by one position and return the item found making the second call to `fetchOne()` return the second document found, if any. When the last data item has been read and `fetchOne()` is called again a NULL value is returned. This ensures that the basic while loop shown works with all languages which implement the X DevAPI if the language supports such an implementation. When using `fetchOne()` it is not possible to reset the internal data item cursor to the first data item to start reading the data items again. An data item - here a Document - that has been fetched once using `fetchOne()` can be discarded by the Connector. The data item's life time is decoupled from the data set. From a Connector perspective items are consumed by the caller as they are fetched. This example assumes that the test schema exists. ```javascript var myColl = db.getCollection('my_collection'); var res = myColl.find('name like :name').bind('name','L%').execute(); var doc; while (doc = res.fetchOne()) { print(doc); } ``` The following example shows how to directly access the rows returned by a `Table.select()` operation. The basic code pattern for result iteration is the same. The difference between the following and the previous example is in the data item handling. Here, `fetchOne()` returns Rows. The exact syntax to access the column values of a Row is language dependent. Implementations seek to provide a language native access pattern. The example assumes that the test schema exists and that the employee table exists in myTable. ```javascript var myRows = myTable.select(['name', 'age']).where('name like :name').bind('name','L%').execute(); var row; while (row = myRows.fetchOne()) { // Accessing the fields by array print('Name: ' + row['name'] + ' '); // Accessing the fields by dynamic attribute print('Age: ' + row.age + ' '); } ``` ### 9.4 Fetching All Data Items at Once In addition to the pattern of using `fetchOne()` explained at Section 9.3, “Working with Data Sets”, which enables applications to consume data items one by one, X DevAPI also provides a pattern using `fetchAll()`, which passes all data items of a data set as a list to the application. The different X DevAPI implementations use appropriate data types for their programming language for the list. Because different data types are used, the language's native constructs are supported to access the list elements. The following example assumes that the test schema exists and that the employee table exists in myTable. ```javascript var myResult = myTable.select(['name', 'age']). where('name like :name').bind('name','L%'). execute(); var myRows = myResult.fetchAll(); for (index in myRows) { print (myRows[index].name + " is " + myRows[index].age + " years old."); } ``` When mixing `fetchOne()` and `fetchAll()` to read from one data set keep in mind that every call to `fetchOne()` or `fetchAll()` consumes the data items returned. Items consumed cannot be requested again. If, for example, an application calls `fetchOne()` to fetch the first data item of a data set, then a subsequent call to `fetchAll()` returns the second to last data item. The first item is not part of the list of data items returned by `fetchAll()`. Similarly, when calling `fetchAll()` again for a data set after calling it previously, the second call returns an empty collection. The use of `fetchAll()` forces a Connector to build a list of all items in memory before the list as a whole can be passed to the application. The life time of the list is independent from the life of the data set that has produced it. Asynchronous query executions return control to caller once a query has been issued and prior to receiving any reply from the server. Calling `fetchAll()` to read the data items produced by an asynchronous query execution may block the caller. `fetchAll()` cannot return control to the caller before reading results from the server is finished. 9.5 Working with SQL Result Sets When you execute an SQL operation on a Session using the `sql()` method an SqlResult is returned. Iterating an SqlResult is identical to working with results from CRUD operations. The following example assumes that the users table exists. ```javascript var res = mySession.sql('SELECT name, age FROM users').execute(); var row; while (row = res.fetchOne()) { print('Name: ' + row['name'] + ' '); print(' Age: ' + row.age + ' '); } ``` SqlResult differs from results returned by CRUD operations in the way how result sets and data sets are represented. A SqlResult combines a result set produced by, for example, `INSERT`, and a data set, produced by, for example, `SELECT` in one. Unlike with CRUD operations there is no distinction between the two types. A SqlResult exports methods for data access and to retrieve the last inserted id or number of affected rows. Use the `hasData()` method to learn whether a SqlResult is a data set or a result. The method is useful when code is to be written that has no knowledge about the origin of a SqlResult. This can be the case when writing a generic application function to print query results or when processing stored procedure results. If `hasData()` returns true, then the SqlResult origins from a `SELECT` or similar command that can return rows. A return value of true does not indicate whether the data set contains any rows. The data set can be empty, for example it is empty if `fetchOne()` returns NULL or `fetchAll()` returns an empty list. The following example assumes that the procedure `my_proc` exists. var res = mySession.sql('CALL my_proc()').execute(); if (res.hasData()){ var row = res.fetchOne(); if (row){ print('List of rows available for fetching. do { print(row); } while (row = res.fetchOne()); } else{ print('Empty list of rows.'); } } else { print('No row result.'); } It is an error to call either fetchOne() or fetchAll() when hasResult() indicates that a SqlResult is not a data set. function print_result(res) { if (res.hasData()) { // SELECT var columns = res.getColumns(); var record = res.fetchOne(); while (record){ for (index in columns){ print (columns[index].getColumnName() + ': ' + record[index] + '\n'); } // Get the next record record = res.fetchOne(); } } else { // INSERT, UPDATE, DELETE, ... print('Rows affected: ' + res.getAffectedItemsCount()); } } print_result(mySession.sql('DELETE FROM users WHERE age < 30').execute()); print_result(mySession.sql('SELECT * FROM users WHERE age = 40').execute()); Calling a stored procedure might result in having to deal with multiple result sets as part of a single execution. As a result for the query execution a SqlResult object is returned, which encapsulates the first result set. After processing the result set you can call nextResult() to move forward to the next result, if any. Once you advanced to the next result set, it replaces the previously loaded result which then becomes unavailable. function print_result(res) { if (res.hasData()) { // SELECT var columns = res.getColumns(); var record = res.fetchOne(); while (record){ for (index in columns){ print (columns[index].getColumnName() + ': ' + record[index] + '\n'); } // Get the next record record = res.fetchOne(); } } 9.6 Working with Metadata Results contain metadata related to the origin and types of results from relational queries. This metadata can be used by applications that need to deal with dynamic query results or format results for transformation or display. Result metadata is accessible via instances of Column. An array of columns can be obtained from any RowResult using the getColumn() method. For example, the following metadata is returned in response to the query SELECT 1+1 AS a, b FROM mydb.some_table_with_b AS b_table. ``` Column[0].databaseName = NULL Column[0].tableName = NULL Column[0].tableLabel = NULL Column[0].columnName = NULL Column[0].columnLabel = "a" Column[0].type = BIGINT Column[0].length = 3 Column[0].fractionalDigits = 0 Column[0].numberSigned = TRUE Column[0].collationName = "binary" Column[0].characterSetName = "binary" Column[0].padded = FALSE Column[1].databaseName = "mydb" Column[1].tableName = "some_table_with_b" Column[1].tableLabel = "b_table" Column[1].columnName = "b" Column[1].columnLabel = "b" Column[1].type = STRING Column[1].length = 20 (e.g.) Column[1].fractionalDigits = 0 Column[1].numberSigned = TRUE Column[1].collationName = "utf8mb4_general_ci" Column[1].characterSetName = "utf8mb4" Column[1].padded = FALSE ``` nextResult(). In addition to the unified API drivers should implement language native iteration patterns. This applies to any type of data set (DocResult, RowResult, SqlResult) and to the list of items returned by fetchAll(). You can choose whether you want your X DevAPI based application code to offer the same look and feel in all programming languages used or opt for the natural style of a programming language. Chapter 10 Building Expressions Table of Contents 10.1 Expression Strings ........................................................................................................ 55 10.1.1 Boolean Expression Strings ........................................................................ 55 10.1.2 Value Expression Strings ............................................................................ 55 This section explains how to build expressions using X DevAPI. When working with MySQL expressions used in CRUD, statements can be specified in two ways. The first is to use strings to formulate the expressions which should be familiar if you have developed code with SQL before. The other method is to use Expression Builder functionality. 10.1 Expression Strings Defining string expressions is straightforward as these are easy to read and write. The disadvantage is that they need to be parsed before they can be transferred to the MySQL server. In addition, type checking can only be done at runtime. All implementations can use the syntax illustrated here, which is shown as MySQL Shell JavaScript code. ```javascript // Using a string expression to get all documents that have the name field starting with 'S' var myDocs = myColl.find('name like :name').bind('name', 'S%').execute(); ``` 10.1.1 Boolean Expression Strings Boolean expression strings can be used when filtering collections or tables using operations, such as `find()` and `remove()`. The expression is evaluated once for each document or row. The following example of a boolean expression string uses `find()` to search for all documents with a “red” color attribute from the collection “apples”: ```javascript apples.find('color = "red"').execute() ``` Similarly, to delete all red apples: ```javascript apples.remove('color = "red"').execute() ``` 10.1.2 Value Expression Strings Value expression strings are used to compute a value which can then be assigned to a given field or column. This is necessary for both `modify()` and `update()`, as well as computing values in documents at insertion time. An example use of a value expression string would be to increment a counter. The `expr()` function is used to wrap strings where they would otherwise be interpreted literally. For example, to increment a counter: ```javascript // the expression is evaluated on the server collection.modify('true').set("counter", expr("counter + 1")).execute() ``` If you do not wrap the string with `expr()`, it would be assigning the literal string "counter + 1" to the "counter" member: Value Expression Strings // equivalent to directly assigning a string: counter = "counter + 1" collection.modify('true').set("counter", "counter + 1").execute() Chapter 11 CRUD EBNF Definitions Table of Contents 11.1 Session Objects and Functions ................................................................. 57 11.2 Schema Objects and Functions ................................................................. 59 11.3 Collection CRUD Functions ....................................................................... 61 11.4 Collection Index Management Functions .................................................... 64 11.5 Table CRUD Functions ............................................................................... 64 11.6 Result Functions ......................................................................................... 66 11.7 Other EBNF Definitions ............................................................................. 69 This chapter provides a visual reference guide to the objects and functions available in the X DevAPI. 11.1 Session Objects and Functions Session The syntax for this object shown in EBNF is: ``` Session ::= '.getSchema(' StringLiteral ') | '.getSchemas()' | '.createSchema(' StringLiteral ') | '.dropSchema(' StringLiteral ') | '.getDefaultSchema()' | '.startTransaction()' | '.commit()' | '.rollback()' | '.setSavepoint()' | '.setSavepoint(' StringLiteral ') | '.releaseSavePoint(' StringLiteral ') | '.rollbackTo(' StringLiteral ') | '.close()' SExecute ``` SqlExecute The syntax for this function shown in EBNF is: ``` SqlExecute ::= '.sql(' SqlStatementStr ')' ( '.bind(' Literal (',' Literal)* ')')* ( '.execute()' )? ``` SQLPlaceholderValues The syntax for this function shown in EBNF is: The syntax for this function shown in EBNF is: ``` SQLPlaceholderName ::= '?' ``` **Figure 11.4 SQLPlaceholderName** --- **SQLLiteral** The syntax for this function shown in EBNF is: ``` SQLLiteral ::= '"' StringLiteral '"' | Number | Document ``` **Figure 11.5 SQLLiteral** --- ### 11.2 Schema Objects and Functions **Schema** The syntax for this function shown in EBNF is: ``` Schema ::= '.getName()' | '.existsInDatabase()' | '.getSession()' | '.getCollection(' StringLiteral ')' | '.getCollections()' | '.getCollectionAsTable(' StringLiteral ')' | '.dropCollection(' StringLiteral ')' | '.getTable(' StringLiteral ')' | '.getTables()' | '.createCollection(' StringLiteral ') ``` Collection The syntax for this function shown in EBNF is: ``` Collection ::= '.getSchema()' | '.getName()' | '.getSession()' | '.existsInDatabase()' | '.replaceAll('DocumentId','DocumentOrJSON')' | '.addOrReplaceOne('DocumentId','DocumentOrJSON')' | '.findOne('DocumentId')' | '.removeOne('DocumentId')' | CollectionFindFunction | CollectionModifyFunction | CollectionAddFunction | CollectionRemoveFunction | CollectionCreateIndex | Collection DropIndex ``` Figure 11.6 Schema Figure 11.7 Collection Table The syntax for this function shown in EBNF is: Table ::= ".getSchema()" | ".getName()" | ".getSession()" | ".existsInDatabase()" | ".isView()" | TableSelectFunction | TableUpdateFunction | TableInsertFunction | TableDeleteFunction 11.3 Collection CRUD Functions CollectionFindFunction The syntax for this function in EBNF is: CollectionFindFunction ::= ".find(' SearchConditionStr? ' ) ( ".fields(' ProjectedDocumentExprStr ' )" )? | ( ".groupBy(' SearchExprStrList ' )")? ( ".having(' SearchConditionStr ' )")? | ( ".sort(' SortExprStrList ' )")? ( ".limit(' NumberOfRows ' ) ( ".offset(' NumberOfRows ' )")? | ( ".lockExclusive(' LockContention ' ) | ".lockShared(' LockContention ' )")? | ( ".bind(' PlaceholderValues ' )")? | ( ".execute()" )? The syntax for this function shown in EBNF is: ``` CollectionModifyFunction ::= '.modify(' SearchConditionStr ')' ( '.set(' CollectionField ',' ExprOrLiteral ')' | '.unset(' CollectionFields ')' | '.arrayInsert(' CollectionField ',' ExprOrLiteral ')' | '.arrayAppend(' CollectionField ',' ExprOrLiteral ')' | '.arrayDelete(' CollectionField ')' | '.patch(' DocumentOrJSON ')') )* ( '.sort(' SortExprStrList ')' )? ( '.limit(' NumberOfRows ')' )? ( '.bind(' PlaceholderValues ')' )? ( '.execute()' )? ``` CollectionAddFunction The syntax for this function shown in EBNF is: ```plaintext CollectionAddFunction ::= ( '.add(' ( DocumentOrJSON | '[' DocumentOrJSON ( ',' DocumentOrJSON )* ']' )? ')' )+ ( '.execute()' )? ``` Figure 11.11 CollectionAddFunction CollectionRemoveFunction The syntax for this function shown in EBNF is: ```plaintext CollectionRemoveFunction ::= '.remove(' SearchConditionStr ')' ( '{'.sort(' SortExprStrList ')'}? ( '{'.limit(' NumberOfRows ')'}? ( '{'.bind(' PlaceholderValues ')'})* ( '{'.execute('}') )? ``` 11.4 Collection Index Management Functions Collection.createIndex() Function The syntax for this function shown in EBNF is: ``` CollectionCreateIndex ::= '.createIndex(' StringLiteral ',' DocumentOrJSON ')' ``` CollectionDropIndex The syntax for this function shown in EBNF is: ``` CollectionDropIndex ::= '.dropIndex(' StringLiteral ')' ``` 11.5 Table CRUD Functions TableSelectFunction `Table.select()` and `collection.find()` use different methods for sorting results. `Table.select()` follows the SQL language naming and calls the sort method `orderBy()`. `Collection.find()` does not. Use the method `sort()` to sort the results returned by `Collection.find()`. Proximity with the SQL standard is considered more important than API uniformity here. The syntax for this function shown in EBNF is: ``` TableSelectFunction ::= '.select(' ProjectedSearchExprStrList? ')' ( '.where(' SearchConditionStr ')' )? ( '.groupBy(' SearchExprStrList ')' )? ( '.having(' SearchConditionStr ')' )? ( '.orderBy(' SortExprStrList ')' )? ( '.limit(' NumberOfRows ')' ( '.offset(' NumberOfRows ')' )? ( '.lockExclusive(' LockContention ')' | '.lockShared(' LockContention ')' )? ( '.bind(' ( PlaceholderValues ) ')' )* ( '.execute()' )? ``` TableInsertFunction The syntax for this function shown in EBNF is: ``` TableInsertFunction ::= '.insert(' ( TableFields )? ') ( '.values(' Literal (',' Literal)* ')' )+ ( '.execute()' )? ``` Figure 11.16 TableInsertFunction TableUpdateFunction The syntax for this function shown in EBNF is: ``` TableUpdateFunction ::= '.update()' ( '.set(' TableField ',' ExprOrLiteral ')' )+ '.where(' SearchConditionStr ') ( '.orderBy(' SortExprStrList ')' )? ( '.limit(' NumberOfRows ')' )? ( '.bind(' ( PlaceholderValues ) ')' )* ( '.execute()' )? ``` 11.6 Result Functions Result The syntax for this function shown in EBNF is: \[ \text{Result} ::= \text{.getAffectedItemsCount()}' | \text{.getAutoIncrementValue()}' | \text{.getGeneratedIds()}' | \text{.getWarningCount()}' | \text{.getWarnings()}' \] The syntax for this function shown in EBNF is: ``` DocResult ::= '.getWarningCount()' | '.getWarnings()' | '.fetchAll()' | '.fetchOne()' | ``` The syntax for this function shown in EBNF is: ``` RowResult ::= '.getWarningCount()' | '.getWarnings()' | '.fetchAll()' | '.fetchOne()' | '.getColumns()' | ``` **Column** The syntax for this function shown in EBNF is: ``` Column ::= '.getSchemaName()' 'getTableName()' 'getTableLabel()' 'getColumnName()' 'getColumnLabel()' 'getType()' 'getLength()' 'getFractionalDigits()' 'isNumberSigned()' 'getCollationName()' 'getCharacterSetName()' 'isPadded()' ``` **SqlResult** The syntax for this function shown in EBNF is: ``` SqlResult ::= '.getWarningCount()' '.getWarnings()' '.fetchAll()' '.fetchOne()' '.getColumns()' '.getAutoIncrementValue()' '.hasData()' ``` 11.7 Other EBNF Definitions SearchConditionStr The syntax for this function shown in EBNF is: ``` SearchConditionStr ::= ""' Expression '"' ``` SearchExprStrList The syntax for this function shown in EBNF is: ``` SearchExprStrList ::= '[' '"' Expression '"' ( ',' '"' Expression '"' )* ']' ``` ProjectedDocumentExprStr The syntax for this function shown in EBNF is: ``` ProjectedDocumentExprStr ::= ProjectedSearchExprStrList | 'expr("' JSONDocumentExpression '")' ``` ProjectedSearchExprStrList The syntax for this function shown in EBNF is: \[ \text{ProjectedSearchExprStrList} ::= \[ \text{Expression} ( \text{AS} \text{ Alias}?)? \] \right\} \text{Expression} ( \text{AS} \text{ Alias}?)? \} \right]* \right]\] SortExprStrList The syntax for this function shown in EBNF is: \[ \text{SortExprStrList} ::= \[ \text{Expression} ( \text{ASC}\mid\text{DESC}?)? \] \right\} \text{Expression} ( \text{ASC}\mid\text{DESC}?)? \} \right]* \right]\] ExprOrLiteral The syntax for this function shown in EBNF is: \[ \text{ExprOrLiteral} ::= \text{expr}('\text{Expression} \text{''}) \mid \text{Literal} \] ExprOrLiterals The syntax for this function shown in EBNF is: \[ \text{ExprOrLiterals} ::= \text{ExprOrLiteral} \left( \text{','} \text{ExprOrLiteral} \right)* \] ExprOrLiteralOrOperand The syntax for this function shown in EBNF is: ``` ExprOrLiteralOrOperand ::= ExprOrLiteral ``` Figure 11.31 ExprOrLiteralOrOperand PlaceholderValues The syntax for this function shown in EBNF is: ``` PlaceholderValues ::= '{' PlaceholderName ':=' ExprOrLiteral '}' ``` Figure 11.32 PlaceholderValues PlaceholderName The syntax for this function shown in EBNF is: ``` PlaceholderName ::= NamedPlaceholderNotQuestionmarkNotNumbered ``` Figure 11.33 PlaceholderName CollectionFields The syntax for this function shown in EBNF is: ``` CollectionFields ::= ( '[' CollectionField ( ',' CollectionField )* ']' ) ``` Figure 11.34 CollectionFields CollectionField The syntax for this function shown in EBNF is: ``` CollectionField ``` DocPath The syntax for this function shown in EBNF is: ``` DocPath ::= ( '[' | ( '[' Index ']' ) | '.*' | ( '.' StringLiteral ) | '**' )+ ``` Figure 11.36 DocPath Literal The syntax for this function shown in EBNF is: ``` Literal ::= "" StringLiteral '"' | Number | true | false | Document ``` Figure 11.37 Literal Expression ``` Expression ::= Literal ``` Expression An API call expecting a JSON document allows the use of many data types to describe the document. Depending on the X DevAPI implementation and language any of the following data types can be used: - String - Native JSON - JSON equivalent syntax - DbDoc - Generated Doc Classes All implementations of X DevAPI allow expressing a document by the special DbDoc type and as a string. The syntax for this function shown in EBNF is: ``` Document ::= JSONDocument | JSONEquivalentDocument | DbDoc | GeneratedDocumentClasses ``` JSONExpression The syntax for this function shown in EBNF is: ``` JSONExpression ::= JSONDocumentExpression | '[' Expression (',' Expression)* '] ``` Figure 11.40 JSONExpression JSONDocumentExpression The syntax for this function shown in EBNF is: ``` JSONDocumentExpression ::= '{' StringLiteral ':' JSONExpression (',' StringLiteral ':' JSONExpression)* '} ``` Figure 11.41 JSONDocumentExpression FunctionName The syntax for this function shown in EBNF is: ``` FunctionName ::= StringLiteral | StringLiteral '.' StringLiteral ``` Figure 11.42 FunctionName DocumentOrJSON The syntax for this function shown in EBNF is: ``` DocumentOrJSON ::= Document | 'expr("" JSONDocumentExpression ")' ``` Figure 11.43 DocumentOrJSON TableField The syntax for this function shown in EBNF is: ``` TableField ::= ( StringLiteral '.' )? ( StringLiteral '.' )? StringLiteral ( '@' DocPath )? ``` Figure 11.44 TableField TableFields The syntax for this function shown in EBNF is: ``` TableFields ::= [ '{' TableField ( ',' TableField )* '}' ] ``` Figure 11.45 TableFields Chapter 12 Expressions EBNF Definitions This section provides a visual reference guide to the grammar for the expression language used in XDevAPI. ident ident ::= ID | QUOTED_ID Figure 12.1 ident schemaQualifiedIdent schemaQualifiedIdent ::= ( ident_schema '.' )? ident Figure 12.2 schemaQualifiedIdent columnIdent columnIdent ::= ( ident '.' ( ident '.' )? )? ident ( ( '->' | '->>' ) "'" '$' documentPath "'" )? Figure 12.3 columnIdent documentPathLastItem documentPathLastItem documentPathItem \[::= \[\]\] \[\[' INT ']\] \['.'\] documentPathMember Figure 12.4 documentPathLastItem ![Diagram](image) documentPathItem \[::=\] documentPathLastItem \[**\] Figure 12.5 documentPathItem ![Diagram](image) documentPath \[::=\] documentPathItem* documentPathLastItem Figure 12.6 documentPath ![Diagram](image) documentField \[::=\] fieldId documentPath* \['$'\] documentPath Figure 12.7 documentField ![Diagram](image) argsList \[ \text{argsList} ::= \text{expr} \ (',\ \text{expr})^* \] Figure 12.8 argsList lengthSpec \[ \text{lengthSpec} ::= '(', \text{INT})' \] Figure 12.9 lengthSpec castType \[ \text{castType} ::= 'SIGNED' 'INTEGER'* \\ | 'UNSIGNED' 'INTEGER'* \\ | 'CHAR' lengthSpec* \\ | 'BINARY' lengthSpec* \\ | 'DECIMAL' ( lengthSpec | '(', \text{INT},',', \text{INT})')? \\ | 'TIME' \\ | 'DATE' \\ | 'DATETIME' \\ | 'JSON' \] Figure 12.10 castType Figure 12.11 functionCall placeholder ::= ':' ID groupedExpr \[ \text{groupedExpr} ::= ( \text{expr} ) \] Figure 12.13 groupedExpr unaryOp \[ \text{unaryOp} ::= ( \text{'!' | '~' | '+' | '-' } ) \text{atomicExpr} \] Figure 12.14 unaryOp literal \[ \text{literal} ::= \text{INT} \mid \text{FLOAT} \mid \text{STRING}_\text{SQ} \mid \text{STRING}_\text{DQ} \mid \text{'NULL'} \mid \text{'FALSE'} \mid \text{'TRUE'} \] jsonKeyValue \[ \text{jsonKeyValue} ::= \text{STRING_DQ} ': ' \text{expr} \] Figure 12.16 jsonKeyValue jsonDoc \[ \text{jsonDoc} ::= '{' ( \text{jsonKeyValue} ( ',', \text{jsonKeyValue} )* )* '}' \] Figure 12.17 jsonDoc jsonarray \[ \text{jsonArray} ::= '[' ( \text{expr} ( ',', \text{expr} )* )* '] \] atomicExpr atomicExpr ::= placeholder | columnOrPath | functionCall | groupedExpr | unaryOp | castOp Figure 12.19 atomicExpr intervalUnit INTERVAL_UNIT ::= 'MICROSECOND' | 'SECOND' | 'MINUTE' | 'HOUR' | 'DAY' | 'WEEK' | 'MONTH' | 'QUARTER' | 'YEAR' Figure 12.20 INTERVAL_UNIT interval interval ::= 'INTERVAL' expr INTERVAL_UNIT Figure 12.21 interval intervalExpr intervalExpr ::= atomicExpr ( { '+' | '-' } interval )* Figure 12.22 intervalExpr mulDivExpr mulDivExpr ::= intervalExpr ( { '*' | '/' | '%' } intervalExpr )* Figure 12.23 mulDivExpr addSubExpr addSubExpr ::= mulDivExpr ( { '+' | '-' } mulDivExpr )* Figure 12.24 addSubExpr shiftExpr shiftExpr bitExpr $$\text{bitExpr ::= addSubExpr \ ( ( '<' | '>' ) addSubExpr )^*}$$ **Figure 12.25 shiftExpr** ![Diagram](image) bitExpr $$\text{bitExpr ::= shiftExpr \ ( ( '&' | '|' | '^' ) shiftExpr )^*}$$ **Figure 12.26 bitExpr** ![Diagram](image) compExpr $$\text{compExpr ::= bitExpr \ ( ( '>=' | '>' | '<=' | '<' | '=' | '<>' | '!=' ) bitExpr )^*}$$ **Figure 12.27 compExpr** ![Diagram](image) ilriExpr $$\text{ilriExpr ::= compExpr IS 'NOT'\* \{ 'NULL' | 'TRUE' | 'FALSE' \} | compExpr 'NOT'\* 'IN' \{ 'argsList' \})' | compExpr 'NOT'\* 'IN' compExpr}$$ 86 \textbf{andExpr} \begin{equation} \text{andExpr} \::= \text{ilriExpr} \ ( ( \&\& \ | \ \text{'AND'} ) \text{ilriExpr} )^* \end{equation} \textbf{Figure 12.29 andExpr} \textbf{orExpr} \begin{equation} \text{orExpr} \::= \text{andExpr} \ ( ( \mid \ | \ \text{'OR'} ) \text{andExpr} )^* \end{equation} expr \[ expr ::= orExpr \] Figure 12.30 orExpr DIGIT \[ DIGIT ::= '0' - '9' \] Figure 12.32 DIGIT FLOAT \[ FLOAT ::= DIGIT* '.' DIGIT+ ( 'E' ( '+' | '-' )* DIGIT+ )* \\ | DIGIT+ 'E' ( '+' | '-' )* DIGIT+ \] Figure 12.33 FLOAT INT INT ::= DIGIT+ Figure 12.34 INT QUOTED_ID QUOTED_ID ::= """" ID """" | """" ( ~"""" | """""""" )* """" Figure 12.35 QUOTED_ID ID ID ::= ( 'a' - 'z' | 'A' - 'Z' | '_' ) ( 'a' - 'z' | 'A' - 'Z' | '0' - '9' | '_' )* Figure 12.36 ID WS WS ::= [ \t\n]+ Figure 12.37 WS SCHAR ::= \u0020\u0021\u0023\u0024\u0025\u0026\u0028-\u005B\u005D-\u007E} Figure 12.38 SCHAR **STRING_DQ** STRING_DQ ::= "" ( SCHAR | "" | ESCAPE_DQ )* "" Figure 12.39 STRING_DQ **STRING_SQ** STRING_SQ ::= "" ( SCHAR | "" | ESCAPE_SQ )* "" Figure 12.40 STRING_SQ Chapter 13 Implementation Notes Table of Contents 13.1 MySQL Shell X DevAPI extensions ................................................................. 93 13.1 MySQL Shell X DevAPI extensions MySQL Shell deviates from the Connector implementations of X DevAPI in certain places. A Connector can connect to MySQL Server instances running X Plugin only by means of X Protocol. MySQL Shell contains an extension of X DevAPI to access MySQL Server instances through X Protocol. An additional ClassicSession class is available to establish a connection to a single MySQL Server instance using classic MySQL protocol. The functionality of the ClassicSession is limited to basic schema browsing and SQL execution. See MySQL Shell 8.0, for more information.
Urban-focused satellite CO2 observations from the Orbiting Carbon Observatory-3: A first look at the Los Angeles megacity Matthäus Kiel, Annmarie Eldering, Dustin D. Roten, John C. Lin, Sha Feng, Ruixue Lei, Thomas Lauvaux, Tomohiro Oda, Coleen M. Roehl, Jean-François Blavier, et al. To cite this version: HAL Id: insu-03231646 https://insu.hal.science/insu-03231646 Submitted on 21 May 2021 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution 4.0 International License Urban-focused satellite CO₂ observations from the Orbiting Carbon Observatory-3: A first look at the Los Angeles megacity Matthäus Kiel a,*, Annmarie Eldering a, Dustin D. Roten d, John C. Lin d, Sha Feng b, j, Ruixue Lei b, Thomas Lauvaux c, Tomohiro Oda e, f, g, Coleen M. Roehl h, Jean-Francois Blavier a, Laura T. Iraci j a Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA b Laboratoire des Sciences du Climat et de l’Environnement, CEA, CNRS, UVSQ/IPSL, Université Paris-Saclay, Orme des Merisiers, Gif-sur-Yvette, France c Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA d Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, PA, USA e Laboratoire des Sciences du Climat et de l’Environnement, CEA, CNRS, UVSQ/IPSL, Université Paris-Saclay, Orme des Merisiers, Gif-sur-Yvette, France f Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT, USA g Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT, USA h Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT, USA i Goddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD, USA j Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA k NASA Ames Research Center, Moffett Field, CA, USA l Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA A R T I C L E I N F O Keywords: Greenhouse gas emissions Carbon dioxide Anthropogenic Fossil fuel Los Angeles Megacity Remote sensing OCO-3 TCCON WRF-Chem X-STILT A B S T R A C T NASA’s Orbiting Carbon Observatory-3 (OCO-3) was designed to support the quantification and monitoring of anthropogenic CO₂ emissions. Its Snapshot Area Map (SAM) and target mode measurements provide an innovative dataset for carbon studies on sub-city scales. Unlike any other current space-based instrument, OCO-3 has the ability to scan large contiguous areas of emission hot spots like cities, power plants, and volcanoes. These measurements result in dense, fine-scale spatial maps of column averaged dry-air mole fractions of carbon dioxide (X CO₂). For the first time, we present and analyze X CO₂ distributions over the Los Angeles megacity (LA) derived from OCO-3 SAM and target mode observations. Urban X CO₂ enhancements range from 0 – 6 ppm (median enhancements ≃ 2 ppm) relative to a clean background and show excellent agreement with nearby ground-based TCCON measurements of X CO₂. OCO-3’s dense observations reveal intra-urban variations of X CO₂ over the city that have never been observed from space before. The spatial variations are mainly driven by the complex fossil fuel emission patterns and meteorological conditions in the LA Basin and are in good agreement with those from co-located TROPOMI measurements of co-emitted NO₂. Differences between measured and simulated X CO₂ enhancements from two models (WRF-Chem and X-STILT) are typically below 1 ppm with larger differences for some sub regions. Both models capture the observed intra-urban X CO₂ gradients. Further, OCO-3’s multi-swath measurements capture about three times as much of the city emissions compared to single-swath overpasses. OCO-3’s frequent target and SAM mode observations will pave the way to constrain urban emissions at finer, sub-city scales. 1. Introduction Urban areas account for more than 70% of the global anthropogenic CO₂ emissions to the atmosphere. The largest emitters are megacities, large urban systems with 10 million or more inhabitants (United Nations Department of Economic and Social Affairs, 2019). The megacities’ rapid growth in population and economic power results in increasing carbon emissions which impact the composition of the atmosphere and the climate on a global scale. For example, the world’s 33 megacities emit more than 20% of the global anthropogenic fossil fuel CO₂ emissions, but cover only about 3% of the Earth’s land surface (Stocker et al. 2013). The Los Angeles megacity (LA) is one of the five largest fossil fuel CO₂ emitters in the world (≈13.5 million inhabitants, ±196.5 ± 43.7 * Corresponding author. E-mail address: matthaeus.kiel@jpl.nasa.gov (M. Kiel). https://doi.org/10.1016/j.rse.2021.112314 Received 31 August 2020; Received in revised form 7 January 2021; Accepted 22 January 2021 Available online 1 March 2021 0034-4257/© 2021 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). MtCO$_2$/year; Moran et al. 2018). It is an international aviation and intermodal transportation hub, including the Los Angeles International Airport, the Port of Los Angeles, and a vast network of interconnected freeways for transportation. Further, large parts of the California oil and gas industry are concentrated primarily in the Greater LA Basin. The city has an extensive oil drilling infrastructure, with several local oil refineries and storage facilities (Chilingar and Endres 2005). The city’s administration has set aggressive goals for a sustainable future. For example, the LA Green New Deal Plan aims to reduce greenhouse gas emissions by 65% by 2035 from 2008 baseline levels, reaching carbon neutrality by 2045 (https://plan.lamayor.org/). To achieve these ambitious goals, it is important to monitor and report anthropogenic carbon sources regularly. In addition to reporting emissions on a voluntary basis or under climate action activities, atmospheric observations of greenhouse gases provide independent measurements that can help to monitor carbon sources as anthropogenic emissions are reflected in atmospheric CO$_2$ concentrations. Several studies used atmospheric observations of CO$_2$ over LA to characterize fossil fuel emissions (Wunch et al. 2009; Brioude et al. 2013; Newman et al. 2013; Hedelius et al. 2018). Typically, urban emissions create persistent and localized CO$_2$ domes over and downwind of large cities that can be detected from space (Idso et al., 1998; Newman et al. 2013). For example, Kort et al. (2012) analyzed CO$_2$ measurements over LA derived from observations collected by the Greenhouse gases Observing Satellite (GOSAT) (Yokota et al. 2009; Kuze et al. 2009). They found statistically significant CO$_2$ enhancements of ≥ 3 parts per million (ppm) compared to measurements over a nearby desert-like background site. Schwander et al. (2017) analyzed single nadir track measurements over LA from NASA’s Orbiting Carbon Observatory-2 (OCO-2; Crisp et al., 2017; Eldering et al., 2017) and found that anthropogenic XCO$_2$ enhancements peak over the urban core (≤ 4–6 ppm) and decrease through suburban areas to rural background values more than 100 km away. Recent studies examined the utility of CO$_2$ data collected from OCO-2 to constrain whole city scale urban emissions including LA (Wu et al. 2018; Wu et al., 2020; Ye et al., 2020). However, the OCO-2 type sampling has difficulties yielding information at sub-city scales. OCO-2 has a long revisit cycle of ∼ 16 days and a narrow swath of ≤ 10.3 km. This only allows a small portion of urban emissions to be detected during a single overpass if the meteorological conditions are favorable. Also, OCO-2 follows a sun-synchronous orbit, meaning that all observations are temporally limited to local afternoon. NASA’s Orbiting Carbon Observatory-3 (OCO-3) includes an observation mode specifically designed to measure anthropogenic emissions and overcome some of the above mentioned limitations. NASA launched the OCO-3 instrument on May 4, 2019 from Kennedy Space Center to the International Space Station (ISS). OCO-3 has the ability to cover large contiguous areas (approximately 80 × 80 km$^2$) on a single overpass over emission hotspots like cities, power plants, or volcanoes. These observational modes are called Snapshot Area Map (SAM) and target mode and collect fine-scale spatial maps of XCO$_2$ unlike what can be done with any other current space-based instrument (Eldering et al. 2019). For example, due to its agile 2-axis pointing mirror assembly (PMA), OCO-3 can measure XCO$_2$ over the entire LA Basin during the span of only two minutes by collecting multiple swaths of data, providing information about XCO$_2$ distributions on sub-city scales. In addition, if the ISS orbit geometry is favorable, OCO-3 can collect SAM or target mode observations over the same area within several days and at different times of the day, giving insights into day-to-day and diurnal variations of intra-urban XCO$_2$ distributions. Here, we present and analyze the very first sub-city scale XCO$_2$ distributions over LA derived from target and SAM mode observations collected by OCO-3 in October 2019 and February 2020. We use data from nearby Total Carbon Column Observing Network (TCCON, Wunch et al. 2011a) stations to validate the OCO-3 measurements over parts of LA and to calculate urban XCO$_2$ enhancements. The dense, high resolution OCO-3 observations reveal intra-urban variations of XCO$_2$ over LA that have never been observed from space before. We relate the observed variations to the underlying meteorological conditions and colocated NO$_2$ measurements from the TROPospheric Monitoring Instrument (TROPOMI). Further, we compare the XCO$_2$ enhancements observed by OCO-3 with simulated values from two independent models that can resolve XCO$_2$ variations across the city: an Eulerian, gridded approach (WRF-Chem) and a time-inverted Lagrangian approach based on air parcels (X-STILT). Finally, we demonstrate the advantage of OCO-3’s multi-swath measurement approach to capture large parts of city emissions compared to single-swath overpasses. 2. Datasets 2.1. OCO-3 XCO$_2$ data The OCO-3 instrument is currently mounted to the Japanese Experimental Module - Exposed Facility (JEM-EF) on board of the ISS and collects solar radiance spectra over the sunlit hemisphere in four observational modes: nadir, glint, target, and SAM. In SAM mode, OCO-3’s agile 2-axis PMA is commanded to collect nearly adjacent swaths of data, resulting in a small map of measurements spanning approximately 80 × 80 km$^2$, collected over a time span of approximately two minutes. During target mode observations, OCO-3 collects a series of relatively long segments (usually 5 or 6 segments) resulting in a sequence of overlapping along-track swaths. Similar to OCO-2, OCO-3’s target mode observations provide the primary dataset for validation of the XCO$_2$ product and are typically taken over sites that operate ground based TCCON instruments (Wunch et al. 2011a, 2017). The overlapping swaths can cover an area of up to ∼ 20 × 80 km$^2$ (compared to 20 × 20 km$^2$ for OCO-2), also creating small maps of XCO$_2$ over TCCON city sites. OCO-3 has also a slightly larger footprint size compared to OCO-2. The OCO-3 along track footprint size is ≤ 2.2 km at nadir and the cross-track footprint size is ≤ 1.6 km, resulting in a slightly larger footprint area (3.5 km$^2$) compared to OCO-2 (3 km$^2$). In this study, we focus on the first XCO$_2$ SAM and target mode observations taken by the OCO-3 instrument over LA in October 2019 and February 2020. We use the OCO-3 vEarly product which is publicly available through the NASA Goddard Earth Science Data and Information Services Center (GES DISC) for distribution and archiving (http://disc.sci.gsfc.nasa.gov/). This product uses the newest Atmospheric Carbon Observations from Space (ACOS, O’Dell et al. 2018) build 10 (b10) software suite using an early Ancillary Radiometric Product (ARP). The vEarly quality filtered and bias corrected XCO$_2$ dataset shows reasonable performance for all viewing modes over land. As described in Taylor et al. (2020), the OCO-3 vEarly data contains time dependent residual pointing errors that occasionally exceed OCO-3’s footprint size, especially for large azimuth and elevation positions of the PMA. The team is currently investigating possible error sources (including timing errors, mounting angles, PMACal correction table updates) to reduce pointing errors in the next reprocessing campaign. For our analysis, we carefully checked the OCO-3 target and SAM mode data for possible pointing errors by investigating radiances levels of OCO-3’s O$_2$ A-band data from coastline crossing. The pointing error in the data analyzed here appears to be below OCO-3’s footprint size and the data is well suited for investigations of city scale XCO$_2$ gradients. A detailed description of the OCO-3 vEarly XCO$_2$ data product and its data quality is given in (Taylor et al. 2020; Osterman et al. 2020). 2.2. TCCON XCO$_2$ data The TCCON is a global network of high-resolution ground-based Fourier Transform Spectrometers that record solar spectra in the near-infrared region. It provides measurements of column-averaged abundances of CO$_2$ and other atmospheric gases such as CH$_4$ and CO. TCCON is the primary validation source for the OCO-3 XCO$_2$ data product and has been used to validate data from multiple satellites, e.g. OCO-2, GOSAT, TROPOMI, and MOPITT (Wunch et al. 2011b; O’Dell et al. 2018; Borsdorf et al., 2018; Kiel et al. 2019; Hedelius et al. 2019). Here, we use the GGS2014 dataset (Wunch et al. 2015) from two TCCON sites in and outside of LA: \( X_{\text{CO}_2} \) data from the Caltech TCCON instrument located in Pasadena, CA (Wennberg et al. 2014), a city northeast of LA which is part of the greater LA metropolitan area, and \( X_{\text{CO}_2} \) data from the TCCON instrument at NASA’s Armstrong Flight Research Center (AFRC, Iraci et al. 2016), located about \( \approx 100 \) km north of LA near Edwards, CA (see Fig. 1). We use the Caltech TCCON data to validate OCO-3 \( X_{\text{CO}_2} \) measurements over the northern part of LA and the TCCON AFRC \( X_{\text{CO}_2} \) dataset to derive background \( X_{\text{CO}_2} \) estimates for each OCO-3 overpass. The AFRC instrument is separated from the greater LA metropolitan area by the San Gabriel mountains which form a natural border between the sparsely populated area around Edwards and LA (see Fig. 1). It is located about 25 km west-southwest of the Mojave desert, one of the driest deserts on Northern America. The biosphere around ARFC consists of cacti and succulents. Both city and background observations are affected similarly by large scale \( \text{CO}_2 \) transport but the AFRC site is impacted minimally by local fluxes. At times the AFRC site is directly downwind of Bakersfield, measurements might be contaminated by anthropogenic \( \text{CO}_2 \) emissions and therefore not suitable as clean \( X_{\text{CO}_2} \) background values. HYSPLIT (Stein et al. 2016) back trajectory calculations indicate that this is not the case for the analyzed days here. ### 2.3. Surface wind data The meteorological conditions in the LA Basin are complex due to local topography and the city’s proximity to the coast. The wind experienced at any given location is highly variable in time and affects the spatiotemporal distribution of \( X_{\text{CO}_2} \) over LA. Typical day time circulations show onshore winds from south-west direction with low wind speeds (\( \approx 2 \) m/s), but circulations can change dramatically from day to day, for example during Santa Ana events when strong easterly winds (\( \approx 8 – 13 \) m/s) travel from the desert into the LA Basin (Rolsinski et al. 2019). We include hourly wind measurements (speed and direction) from the National Centers for Environmental Prediction (NCEP) ADP Global Surface Observational Weather Data in our analysis (NCEP 2004). The data are composed of surface weather reports operationally collected by NCEP and include land and marine surface reports. We use data from eight stations in and around the LA Basin in our study. In addition, we use hourly wind data from seven surface measurement stations operated by the South Coast Air Quality Management District (SCAQMD). An overview of the station locations is given in Fig. 1. ### 2.4. WRF-Chem model simulations Our Weather Research and Forecasting model with chemistry (WRF-Chem) setup and parameterizations follow the best combination concluded by Feng et al. (2016). The innermost domain (1.3 km spatial resolution in latitude and longitude) fully covers the OCO-3 SAM and target mode observations over LA. We choose the ERA5 reanalysis (Hersbach et al. 2020) for the meteorological initial and lateral boundary conditions and nudge the WRF-Chem transport to ERA5 through Four Dimensional Data Assimilation (Deng and Stauffer 2006). This modification offers better constraints to the model transport compared to the setup used in Feng et al. (2016). We use monthly \( 1 \times 1 \) km\(^2\) fossil fuel emission estimates from the Open-source Data Inventory for Atmospheric Carbon dioxide (ODIAC) Version 2019 (ODIAC2019, Oda et al. 2018) with refined point source information in and around LA. The \( \text{CO}_2 \) mole fractions at each model grid represent fossil fuel \( \text{CO}_2 \) mole fractions (note that we do not add background or biogenic \( \text{CO}_2 \) mole fractions because we are only interested in \( \text{CO}_2 \) enhancements over LA). Finally, we apply OCO-3’s pressure weighting functions (PWF) and averaging kernels (AK) to the model data following Rodgers and Connor (2003). ### 2.5. X-STILT simulations We carry out simulations using the column-averaged Stochastic Time-Inverted Lagrangian Transport (X-STILT) model to generate grid-averaged \( \text{CO}_2 \) values at column receptors separated by \( \approx 0.02^{\circ} \) latitude and \( \approx 0.02^{\circ} \) longitude across the LA Basin. From each receptor, an ensemble of air parcels is tracked backwards in time for \( \approx 24 \) h from discretized values within the column, all other model parameters are identical to the setup used in Wu et al. (2018). The PWF and AK are applied to the discretized release points within the column-receptor using values from the nearest available OCO-2 sounding (Wu et al. 2018). The air parcels follow three-dimensional wind fields provided from NOAA’s High Resolution Rapid Refresh (HRRR) system (Alexander et al. 2010). The locations and amount of time that parcels spent within the planetary boundary layer are used to calculate the influence footprint, indicating the influence that a particular source region has on the downwind column-receptor (Lin et al. 2003; Fasoli et al. 2018). Each influence footprint is convolved with the monthly ODIAC emissions (Oda and Maksyutov 2011; Oda et al. 2018) to determine the spatially resolved upwind contributions (in ppm) to the column-receptor location. Identical to our WRF-Chem model setup, we use the ODIAC2019 emission inventory with refined point source information in and around LA. ### 2.6. TROPOMI \( \text{NO}_2 \) data The TROPOspheric Monitoring Instrument (TROPOMI) on board of the Copernicus Sentinel-5 Precursor (SSP) satellite was launched in 2017 and measures tropospheric column densities of several key atmospheric species. The spatial resolution is \( \approx 3.5 \times 5.5 \) km\(^2\) (from August 2019 onward) and provides almost daily global coverage before filtering soundings that are contaminated by clouds (Veeckind et al. 2012). NO₂ can serve as an independent tracer of atmospheric pollution. It is simultaneously emitted with CO₂ into the atmosphere as part of anthropogenic activities like fossil fuel combustion and biomass burning. Due to the short lifetime of NO₂ (∼ hours), the pollutant typically remains close to the emission source and measured column densities can easily exceed NO₂ background concentrations by several orders of magnitude, making it a suitable proxy of co-emitted CO₂ from combustion sources. A single TROPOMI overpass can be sufficient to identify strong NO₂ point sources. Reuter et al. (2019) showed that TROPOMI NO₂ measurements can help to identify urban CO₂ plumes. To better characterize the spatiotemporal variability of X_CO₂ over LA, we relate X_CO₂ from OCO-3 to co-emitted NO₂ concentration as observed by TROPOMI. We use the SSP offline Level 2 version 1.03.02 NO₂ data product (van Geffen et al. 2019). We filter for data with quality values below 0.5 which indicate soundings that are contaminated by clouds (Veefkind et al. 2012). For the target observations, we observe similar X_CO₂ passes. We aggregate target mode data into 0.02° longitude grid cells for better visualization of the overlapping swaths. The median X_CO₂ averaged over all swaths is 415.66 ± 2 hours of the OCO-3 overpass (see Table 1). The target mode observations cover an area of approximately 20 × 40 km² which we divide into three regions: 1) suburban: mainly residential areas including the Caltech TCCON site in Pasadena; 2) urban: a dense network of manufacturing factories and roads for transportation; and 3) coastal: a major shipping and industrial hub including multiple petroleum refineries supplying the Los Angeles International Airport and Port of Los Angeles. In addition, the SAM observation on February 24, 2020 extends to the San Fernando Valley, an urbanized valley north of the larger, more populous LA Basin. An illustration of the different regions covered by each overpass is given in Fig. A.11. For all days, the X_CO₂ values as a function of time are shown in Fig. 2. For the target observations, we observe similar X_CO₂ variations for each overlapping swath. The median X_CO₂ averaged over all swaths is 410.57 ± 1.14 ppm on October 7, 2019, 408.68 ± 0.73 ppm on October 11, 2019, and 410.51 ± 0.86 ppm on October 15, 2019. For the SAM on February 24, 2020, the X_CO₂ distribution varies for the adjacent swaths because each swath covered a different area over LA. The median X_CO₂ averaged over all swaths is 415.66 ± 2.18 ppm. ### 3.1. OCO-3 target and SAM measurements We focus on three OCO-3 target mode overpasses and one SAM observation over LA in 2019 and 2020. The three target mode measurements were taken on October 7, 2019 at 12:50 local time (UTC + 7), October 11, 2019 at 11:12 (UTC + 7), and October 15, 2019 at 9:35 UTC + 7. The SAM observation took place on February 24, 2020 at 12:00 UTC + 8. The scanning time of each observation took approximately two minutes. A total of five to six overlapping swaths were recorded in target mode and six adjacent swaths in SAM mode. We only include measurements over land in our analysis. All four overpasses took place under clear-sky conditions leading to several hundred good soundings (N_valid) per overpass after quality filtering (see Table 1). The target mode observations cover an area of approximately 20 × 40 km² which we divide into three regions: 1) suburban: mainly residential areas including the Caltech TCCON site in Pasadena; 2) urban: a dense network of manufacturing factories and roads for transportation; and 3) coastal: a major shipping and industrial hub including multiple petroleum refineries supplying the Los Angeles International Airport and Port of Los Angeles. In addition, the SAM observation on February 24, 2020 extends to the San Fernando Valley, an urbanized valley north of the larger, more populous LA Basin. An illustration of the different regions covered by each overpass is given in Fig. A.11. For all days, the X_CO₂ values as a function of time are shown in Fig. 2. For the target observations, we observe similar X_CO₂ variations for each overlapping swath. The median X_CO₂ averaged over all swaths is 410.57 ± 1.14 ppm on October 7, 2019, 408.68 ± 0.73 ppm on October 11, 2019, and 410.51 ± 0.86 ppm on October 15, 2019. For the SAM on February 24, 2020, the X_CO₂ distribution varies for the adjacent swaths because each swath covered a different area over LA. The median X_CO₂ averaged over all swaths is 415.66 ± 2.18 ppm. ### Table 1 Summary of the OCO-3 target and SAM observations over LA. <table> <thead> <tr> <th>Date</th> <th>Time (local)</th> <th>Mode</th> <th># Swaths</th> <th>N_valid</th> <th>Covered Area</th> </tr> </thead> <tbody> <tr> <td>Oct. 7, 2019</td> <td>12:50</td> <td>target</td> <td>5</td> <td>465</td> <td>≤ 20 × 40 km²</td> </tr> <tr> <td>Oct. 11, 2019</td> <td>11:12</td> <td>target</td> <td>5</td> <td>519</td> <td>≤ 17 × 40 km²</td> </tr> <tr> <td>Oct. 15, 2019</td> <td>09:35</td> <td>target</td> <td>6</td> <td>442</td> <td>≤ 20 × 40 km²</td> </tr> <tr> <td>Feb. 24, 2020</td> <td>12:00</td> <td>SAM</td> <td>5</td> <td>659</td> <td>≤ 2300 km² (total)</td> </tr> </tbody> </table> ### 3.2. Urban X_CO₂ enhancements To derive X_CO₂ enhancements for each overpass, we subtract the background measurements taken by the AFRC TCCON instrument from the OCO-3 observations over LA. The difference provides the additional X_CO₂ within the LA Basin mainly due to local emissions. We average AFRC TCCON X_CO₂ values within ±1 h of the OCO-3 mean overpass times to estimate a clean X_CO₂ background. Then, we subtract the background from the OCO-3 X_CO₂ to calculate enhancements over the city for each day. We expect that the calculated enhancements are mainly driven by anthropogenic emissions. Several studies show that the solar-induced chlorophyll fluorescence signal is low over the Greater LA Basin during the time period of the OCO-3 target and SAM observations (Frankenberg et al. 2011; Sun et al. 2018; Yu et al. 2019). Kort et al. (2012) showed that enhancements over LA are a robust feature of the region attributable to anthropogenic emissions and not affected by seasonally varying changes in biospheric fluxes. Here, we assume that the city and background are similarly impacted by biospheric fluxes such that the calculated differences mainly represent enhancements due to local city emissions. The X_CO₂ background values and calculated city enhancements are shown in Fig. 2. We estimate similar background X_CO₂ values of 408.35 ± 0.22 ppm, 408.52 ± 0.25 ppm, and 408.72 ± 0.35 ppm for October 7, October 11, and October 15, 2019, respectively. On February 24, 2020, we estimate a background value of 413.55 ± 0.29 ppm. The reported errors represent the variance of the TCCON X_CO₂ values within ±1 h of the OCO-2 mean overpass time. On three days (October 7, October 15, 2019, and February 24, 2020), the OCO-3 instrument measured X_CO₂ abundances over LA (mainly outside the urban core) that match the X_CO₂ background. On October 11, 2019, for large parts of the city, the X_CO₂ background is higher than the observed X_CO₂, however, in good agreement with the background values on October 7 and 15, 2019. X_CO₂ differences between the background and city can become negative due to local meteorological conditions, e.g., Santa Ana winds. Santa Ana winds are strong katabatic winds arising in higher altitudes and blowing down towards sea level, traveling from the east into the city (Rolinski et al. 2019). The AFRC TCCON measurements are minimally impacted by these events due to its remote location. However, Santa Ana winds ventilate the LA Basin and push urban emissions over the Pacific Ocean, leading to small or negative differences between background and city observations. ### 3.3. Intra-urban variability of X_CO₂ enhancements Fig. 3 shows X_CO₂ enhancements over LA for the four OCO-3 overpasses. We aggregate target mode data into 0.02° × 0.02° latitude-longitude grid cells for better visualization of the overlapping swaths. The observed X_CO₂ enhancements over LA show different spatial distributions on all four days. In the following, we describe the observed intra-urban variability of X_CO₂ enhancements over LA sorted by complexity (simple to complex). Unless otherwise stated, we propagate the variability of the OCO-3 X_CO₂ values within each sub region (defined in Fig. A.11) and the TCCON X_CO₂ background uncertainty to calculate X_CO₂ enhancement uncertainties. On October 15, 2019, X_CO₂ enhancements over LA are on average 1.79 ± 0.80 ppm, with the largest enhancements over the industrial coastal area (2.71 ± 0.71 ppm). SCAQMD and NCEP stations measured onshore winds (coming from west-south-west direction) with moderate wind speeds of 2–3 m/s within ±2 hours of the OCO-3 overpass (see Fig. 4). On February 24, 2020, the wind stations measured slightly larger wind speeds (3–4 m/s), pushing airmasses (volumes of air) from the coast towards the southern urban city core, where the average enhancement is 2.88 ± 1.11 ppm with single sounding X_CO₂. enhancements of up to 6 ppm. The average enhancement over the valley is $1.39 \pm 1.23$ ppm and $1.82 \pm 0.77$ ppm over the suburbs. On October 7, 2019, $X_{CO_2}$ enhancements are on average $1.72 \pm 0.88$ ppm over the entire city. The largest enhancements occur over the suburban area with individual measurements reaching enhancements of up to $6.37 \pm 0.59$ ppm. Similar to the overpasses on October 15, 2019 and February 24, 2020, the surface wind stations measured onshore winds but with wind speeds partially exceeding 6 m/s. We assume that the strong onshore winds push airmasses from the coastal and urban areas towards the suburbs where the San Gabriel Mountains form a natural barrier and atmospheric $CO_2$ accumulates. On October 11, 2019, $X_{CO_2}$ enhancements are on average $0.21 \pm 0.59$ ppm over LA with the highest enhancements near the coast ($1.09 \pm 0.69$ ppm) and negative enhancements over large parts of the city (e.g. as low as $-0.89 \pm 0.41$ ppm for individual measurements over the suburbs). As discussed in the previous section, wind data from the NCEP and SCAQMD ground based networks indicate Santa Ana like conditions with the wind traveling from east to west and wind speeds exceeding 10 m/s, pushing airmasses out of the LA Basin over the Pacific Ocean. HYSLPLIT model runs indicate that the easterly winds push clean air from higher altitudes (up to 1500 m a.s.l.) into the LA Basin which causes negative $X_{CO_2}$ enhancements (not shown here). ### 3.4. Comparisons to co-located TROPOMI $NO_2$ measurements Multiple studies demonstrated the usefulness of regionally co-located satellite observations of $NO_2$ and $X_{CO_2}$ (Reuter et al. 2014; Hakkarainen et al. 2019). For example, Reuter et al. (2019) used TROPOMI’s $NO_2$ data to identify OCO-2 $X_{CO_2}$ enhancements of localized (up to city-scale) emissions. Here, we relate $X_{CO_2}$ from OCO-3 measurements to co-emitted $NO_2$ concentration as observed by TROPOMI to verify that the observed $X_{CO_2}$ distributions represent a true signal that is driven by local emissions. The TROPOMI instrument collected data over LA within three hours of the OCO-3 overpass on three days analyzed here. On October 7, 2019 the TROPOMI overpass was $\pm 1$ h after the OCO-3 overpass, and on October 11, 2019, $\pm 3$ h after the OCO-3 overpass. On February 24, 2020, the TROPOMI overpass took place $\pm 25$ min after the OCO-3 overpass. There is no co-located data within five hours of the OCO-3 overpass on October 15, 2019. A direct comparison between data from both instruments is challenging due to the short lifetime of $NO_2$ and the temporal mismatch (in addition to instrumental differences and sensitivities), however, the spatial distribution of TROPOMI’s $NO_2$ over LA is similar to the spatial distribution of $X_{CO_2}$ measured by OCO-3: higher $NO_2$ concentrations over the suburbs to the northeast on October 7, 2019; low $NO_2$ concentrations over large parts of the city on October 11, 2019; and enhanced $NO_2$ concentration over the urban core on February 24, 2020 (see Fig. 5). TROPOMI’s wide-swath $NO_2$ measurements help to set the $X_{CO_2}$ city enhancements into context. TROPOMI $NO_2$ measurements are taken in the UV-visible spectral region (425–465 nm) and are less sensitive to clouds and aerosols compared to OCO-3. The observed spatial correlation between both datasets suggests that the observed $X_{CO_2}$ enhancements over LA are dominated by local $X_{CO_2}$ emissions and are less likely due to remaining artifacts in the OCO-3 vEarly $X_{CO_2}$ data product. ### 3.5. Summary Our derived $X_{CO_2}$ enhancements of 0 – 6 ppm (with median enhancements under 2 ppm) over LA are in good agreement with previous studies (Wunch et al. 2009; Kort et al. 2012; Wong et al. 2015; Hedelius et al. 2018). On three days, the OCO-3 target and SAM observations capture $X_{CO_2}$ values that are comparable to background $X_{CO_2}$ values measured at the AFRC TCCON site. This demonstrates that OCO-3’s multi-swath measurement approach reasonably captures city enhancements and background values at the same time on a single overpass. Moreover, OCO-3 measurements reveal fine-scale, intra-urban $X_{CO_2}$ variations over LA with unprecedented spatial coverage. Comparisons to data from NCEP and SCAQMD wind stations show that these fine-scale, intra-urban $X_{CO_2}$ variations are highly sensitive to the underlying complex meteorological conditions in the LA Basin. Further, the observed intra-urban $X_{CO_2}$ variations are in good agreement with co-located TROPOMI $NO_2$ data. Data from both instruments show similar spatial distributions over LA. ### 4. Validation against TCCON TCCON is the primary validation source for the OCO-3 $X_{CO_2}$ data product. Here, we compare OCO-3 $X_{CO_2}$ data collected during the target and SAM measurements over LA with coincident TCCON $X_{CO_2}$ data from the Caltech instrument located in Pasadena. The instrument is located in the suburbs north-east of the urban city center, an area that was sampled by OCO-3 during all four overpasses (see Fig. 3). For our analysis, we include OCO-3 soundings within $\pm 0.1^\circ$ in latitude and longitude (an area of approximately $20 \times 20$ km$^2$) around the Caltech TCCON instrument. In the following, we compare absolute $X_{CO_2}$ values rather than $X_{CO_2}$ enhancements. Fig. 3. OCO-3 $X_{\text{CO}_2}$ enhancements over LA for the three target mode measurements in October 2019 and the SAM observation on February 24, 2020. The target mode measurements extend from the suburbs through the urban to the coastal area. In addition, the SAM observation collects data over the Valley. The markers indicate the Caltech TCCON instrument (⋆1), Downtown LA (⋆2), the Los Angeles International Airport (⋆3), and the San Fernando Valley (⋆4). Target mode data is aggregated into 0.02° × 0.02° latitude-longitude grid cells for better visualization of the overlapping swaths. Fig. 4. Wind rose diagrams for October 7, 2019 (upper left), October 11, 2019 (upper right), October 15, 2019 (lower left), and February 24, 2020 (lower right) using data from NCEP and SCAQMD surface wind stations within the LA Basin. Shown are wind directions and wind speeds within ±2 h of the OCO-3 overpass times. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) We take TCCON data into account within ±30 min of the OCO-3 overpass time for all days except for October 11, 2019 when we expand the time window to ±2 h due to a limited number of TCCON measurements. To further improve our co-location criterion, we only take OCO-3 soundings into account along the line of sight (LOS) of the TCCON instrument. We apply an averaging kernel correction following O’Dell et al. (2018) and convolve the TCCON retrieved CO₂ profile with the OCO-3 column AK before comparing to OCO-3 data. The magnitude of the AK correction is on average 0.16 ppm. Finally, we calculate the median XCO₂ value for each OCO-3 overpass and co-located TCCON data. On all four days, the XCO₂ values are in excellent agreement with the TCCON data (see Table 2). The comparisons indicate a root mean square error (rmse) of 0.23 ppm and a nearly perfect correlation between both data sets (see Fig. 6). This comparison shows that OCO-3’s target and SAM observations capture the day to day variability of several ppm in XCO₂ as seen by the TCCON instrument over Pasadena. 5. Model comparison 5.1. Sampling of model output We choose the model output closest to the OCO-3 overpass time on each day and sample the modeled XCO₂ enhancements at the location of each OCO-3 footprint. For target overpasses we aggregate the sampled model data into 0.02° × 0.02° latitude-longitude grid cells. The median XCO₂ enhancements for each model and region are summarized in Fig. 7. Maps of the modeled XCO₂ enhancements, in native resolution and sampled at the location of the OCO-3 footprints, as well as the differences between modeled and OCO-3 XCO₂ enhancements are depicted in Fig. 8 for WRF-Chem and Fig. 9 for X-STILT. Unless otherwise stated, we use the median of all soundings that fall into the valley, coastal, urban, and suburban region (see Fig. A.11) to describe enhancements and differences between model and observation. The reported uncertainties represent the variability of the modeled XCO₂ values within each sub region. 5.2. Comparison between modeled and observed intra-urban variability of XCO₂ On October 7, 2019, modeled XCO₂ enhancements agree within the calculated errors over the suburbs. OCO-3 observed median XCO₂ enhancements of 3.07 ± 1.08 ppm. The WRF-Chem median enhancement is 2.30 ± 0.36 ppm over the suburbs and 1.84 ± 0.60 ppm for X-STILT over the same region (see Figs. 8 and 9). In contrast to the OCO-3 observations, the median enhancement from X-STILT is larger over the urban area than over the suburbs or coastal region. Over the same region near the coast, WRF-Chem enhancements are significantly smaller (0.35 ± 0.16 ppm) compared to OCO-3 (1.86 ± 0.65 ppm). Nonetheless, the modeled enhancements capture most of the observed intra-urban variability. The full domain of the WRF-Chem model run (see Fig. 8, upper left) indicates a latitudinal and longitudinal shift (in south-east direction) between model and observation. This shift, which is likely driven by a combination of model transport errors and potential errors and biases in the emission inventory, demonstrates the model’s ability to capture intra-urban XCO₂ gradients: larger XCO₂ enhancements over the suburbs and decreasing through the urban core to the coast (see Fig. 7). The same holds for the X-STILT model run where a longitudinal shift (in north direction) is apparent between the modeled and observed XCO₂ enhancement maps (see Fig. 9, upper left). On this day, wind stations measured onshore winds within ±1 h of the OCO-3 overpass, whereas HYSPLIT back trajectory calculations up to 6 h prior to the OCO-3 overpass indicate complex circular winds, attesting the highly variable meteorological conditions in the LA Basin. On October 11, 2019, both modeled XCO₂ enhancements are in good agreement with the space-based observations. The largest differences occur near the coast where OCO-3 enhancements (1.09 ± 0.69 ppm) appear higher than both models (WRF-Chem: 0.20 ± 0.12 ppm; X-STILT: 0.41 ± 0.08 ppm; see Fig. 7). The simulated full domains of both models indicate that the strong easterly winds carry urban emissions out over the Pacific Ocean. On October 15, 2019, modeled XCO₂ enhancements agree well over the urban region (OCO-3: 1.91 ± 0.70 ppm; WRF-Chem: 1.84 ± 0.53 ppm; X-STILT: 1.95 ± 0.63 ppm). Over the coastal region, both modeled XCO₂ enhancements are biased low against the observation. On this day, the OCO-3 overpass took place in the morning (≈ 9:35 PDT). For LA, the marine boundary layer traps nighttime emissions in the basin for several hours until the Planetary Boundary Layer (PBL) collapses after the sun heats up the surface and speeds up the vertical mixing. This usually happens around local noon (Feng et al. 2016). Simulating the correct PBL height is challenging for many models. Moreover, the full domain of the X-STILT simulation (see Fig. 9, third row left) shows individual XCO₂ plumes near the coast that are directed towards the Pacific Ocean. This is in contrast to the surface wind measurements that suggest onshore winds during the time of the overpass. This indicates a wind direction bias between the driving HRRR meteorological fields and the SCAQMD and NCEP surface measurements and is likely to cause lower than observed XCO₂ enhancements over the suburbs and near the coast. On February 24, 2020, both models underestimate the observed enhancements over the entire scene (OCO-3: 2.11 ± 1.28 ppm; WRF-Chem: 1.06 ± 0.53 ppm; X-STILT: 0.89 ± 0.77 ppm). The largest bias is over the urban and coastal areas with modeled XCO₂ enhancements lower than the observation. The same holds for the suburbs and valley but with smaller differences between model and observation. Even though both models underestimate the absolute observed XCO₂ enhancements, they capture the relative spatial variability over LA as observed by OCO-3: low XCO₂ enhancements over the suburbs and increasing through the urban core to the coastal area and, as expected, smaller enhancements in the less populated valley. 5.3. X-STILT-based emission source attribution Here, we use the X-STILT model to allocate observed XCO₂ enhancements to surface-based sources. These sources, represented by ODIAC2019, have the potential to contribute to modeled XCO₂ enhancements. Using X-STILT’s unique backwards-in-time approach, contributing surface sources are identified for each modeled XCO₂ value at each receptor in the domain (see Fig. 9, left column). After sampling this domain at individual OCO-3 sounding locations (i.e., receptors), associated surface contributions are summed for each receptor, and then divided by the number of receptors within the domain. Fig. 10 shows the spatially resolved XCO₂ enhancements due to the various emission sources across LA for the suite of OCO-3 measurement receptors, on average. In the three target mode cases, the contributing surface sources lie directly below the OCO-3 track. CO₂ emitted from these sources has little time to undergo advective transport. Thus, anthropogenic sources in these regions will contribute the most to observations. Surface emissions from the 24 h period leading up to the overpass time are also included. The lower surface CO₂ emissions to the northwest and southeast demonstrate the complex meteorology associated with the LA Basin. The effects of the Santa Ana winds are also evident in surface contributions. On two occasions (October 7, 2019 and October 15, 2019), surface contributions originate from the San Fernando Valley to the northwest and along the coast to the southeast. The wind fields on both days appear relatively calm, however, on October 11, 2019, the surface CO₂ contribution arrives predominantly from the east of the target overpass. This corresponds to strong easterly Santa Ana winds. These winds minimize CO₂ from the San Fernando Valley and coastal region. The three target observations demonstrate that even though space-based XCO₂ measurements are collected in consistent geographic regions, the sources of XCO₂ enhancements are highly variable. Expanding beyond target observations, the unique SAM mode that OCO-3 offers sees more surface CO₂ emissions than alternative sampling modes. The SAM mode case included in Fig. 10 collects higher magnitudes of surface emissions over larger areas than target mode observations. These larger areas are useful for measuring rural-to-urban and sub-city gradients in addition to XCO₂ regional background values. Further, we analyze how much more of the CO₂ surface emissions are captured by OCO-3’s SAM measurements compared to a single nadir Fig. 8. WRF-Chem $X_{CO_2}$ enhancements over LA on October 7, 2019 (first row), October 11, 2019 (second row), October 15 (third row), and February 24, 2020 (fourth row). Shown are the simulated $X_{CO_2}$ enhancements over the Greater LA Metropolitan Area in native spatial resolution (left column), sampled at the OCO-3 footprint locations (center column), and the difference between WRF-Chem and observed OCO-3 $X_{CO_2}$ enhancements ($\Delta X_{CO_2}$ defined as model minus observation, right column). Data is aggregated into 0.02° × 0.02° latitude-longitude grid cells for target mode observations. Markers represent the same locations as in Fig. 3. Fig. 9. Same as Fig. 8 for the X-STILT model. Fig. 10. Surface-based sources of CO₂ contributing to modeled XCO₂ values, as informed by X-STILT and ODIAC. Shown are the averaged contributions (in ppm) contributing to the overall mean of the modeled XCO₂ in the domain. Values are gridded at the resolution of the ODIAC emission inventory (1 × 1 km²). The white polygons indicate the position of the OCO-3 footprints (receptors). 5.4. Discussion The magnitude of the observed $X_{CO_2}$ enhancements over LA is in good agreement with modeled enhancements from WRF-Chem and X-STILT. Median $X_{CO_2}$ differences between model and observation are typically below 1 ppm over LA, with larger differences for some sub regions. The uncertainty spread is larger for OCO-3 than for both models and, in general, largest when $X_{CO_2}$ enhancements are large as well. Model transport errors can result in latitudinal and longitudinal shifts between modeled and observed $X_{CO_2}$ maps. Nonetheless, both models are able to capture intra-urban $X_{CO_2}$ gradients similar to the OCO-3 observations. The spatial distribution of $X_{CO_2}$ over LA is caused by a combination of different meteorological conditions (wind speed, wind direction, PBL height, vertical mixing, etc.) over a time span of hours. It is challenging to fully capture these complex conditions by models. For example, even small biases in the modeled wind speeds and wind directions can result in differences between model and observation of the order of several ppm (Feng et al. 2016). As discussed in Sect. 3.2, the underlying biospheric fluxes are small for the area and time period analyzed here. However, this is not necessarily true during the height of the growing season (May-July). During this time, a potential biospheric uptake outside of the urban region might lower the background $X_{CO_2}$ and urban enhancements may appear larger. Further, we assume that both city and background are affected similarly by biospheric activity. On the other hand, a study analyzing flask samples of isotopic $^{13}$CO2 in the LA Basin indicates that biospheric fluxes can contribute to surface CO2 enhancements by up to 20%, especially during the northern hemisphere winter season (Miller et al. 2020). In the future, continuous measurements of urban biosphere fluxes are needed to further study the impact of lawns, parks, or golf courses in the city on anthropogenic emission signals. On all four days, both models tend to underestimate the observed $X_{CO_2}$ enhancements near the coast where most of the point sources are located. We cannot rule out that a small portion of the model-observation differences are driven by potential biases in emission estimates and spatial distributions in the ODIAC2019 emission inventory (Gurney et al. 2019; Oda et al. 2019). In this study, we use monthly ODIAC2019 fossil fuel emission estimates without hourly scaling (Nassar et al. 2013). Emissions in megacities typically have two peaks during the morning and afternoon traffic and a daytime minimum around local noon. However, this effect is rather small and contributes minimally ($\approx 0.2$ ppm) to the model-observation differences. The lack of explicit traffic emissions in the ODIAC2019 inventory is also unlikely to cause the observed differences. We do not see significant intra-urban scale differences particularly due to traffic when we compare WRF-Chem simulation over LA using ODIAC2019 and Hestia (Oda et al., 2021, not shown here). In general, model-observation differences can be due to the errors in the transport, emissions, and observation itself, or all combined and will be investigated in future studies. Analyzing X-STILT’s source-receptor sensitivities, the sensitivity of downwind CO2 variations to upwind fluxes, show that OCO-3’s SAM observations capture about three times as much of the city emissions compared to single-swath overpasses. Future studies using OCO-3 target and SAM observations will help to constrain city emissions on sub-city scales and offer insights to examine potential errors and biases in emission inventories. 6. Summary OCO-3’s multi-swath measurement approach allows collection of dense maps of $X_{CO_2}$ over emission hot spots and is potentially able to capture intra-urban $X_{CO_2}$ variations from space with unprecedented spatial resolution. Here, we presented and analyzed $X_{CO_2}$ distributions over LA derived from target and SAM mode observations taken by OCO-3. The observed $X_{CO_2}$ distributions over LA are highly sensitive to the underlying, complex meteorological conditions. $X_{CO_2}$ measurements capture about three times as much of the city emissions as clean background values. Our derived enhancements of 0–6 ppm are in good agreement with previous studies. On three days, the OCO-3 target and SAM observations were not only able to reveal unique intra-urban $X_{CO_2}$ distributions over LA, but also captured $X_{CO_2}$ values that agree with background concentration measured by the AFC TCCON instrument. This demonstrates that OCO-3’s multi-swath measurement approach is able to capture city enhancements and background values at the same time on only one single overpass. Comparisons of the observed and modeled $X_{CO_2}$ enhancements from two independent models (WRF-Chem and X-STILT) show an overall good agreement. Median $X_{CO_2}$ differences between model and observation are typically below 1 ppm over LA with larger differences over some sub regions. Both models are able to capture the observed intra-urban $X_{CO_2}$ gradients. Analyzing X-STILT’s source-receptor sensitivities, we found that OCO-3’s SAM observations capture about three times as much of the city emissions compared to single-swath overpasses. The source-receptor sensitivity study also shows that even though space-based $X_{CO_2}$ measurements are collected over the same region, the sources of $X_{CO_2}$ enhancements are highly variable. OCO-3’s SAM and target mode measurements provide an innovative dataset for carbon studies on sub-city scale. The emission coverage by OCO-3 will help to constrain urban emissions at finer spatiotemporal scales, especially in regions with limited ground-based monitoring capabilities. This work shows that future wide-swath CO2 missions with OCO-3 type dense sampling and short revisit times, for example GeoCarb (Moore III et al. 2018), AimNorth (Nassar et al. 2019), or CO2M (Sierk et al. 2019), can play a major role in quantifying enhancements over urban areas, potentially monitoring the effectiveness and progress of localized CO2 emission reduction policies. Author contributions M.K.: Conceptualization, Methodology, Formal analysis, Investigation, Software, Validation, Visualization, Writing - original draft; Writing - review & editing; A.E.: Conceptualization, Methodology, Project administration, Supervision, Writing - review & editing; D.D.R.: Formal analysis, Investigation, Visualization, Writing - review & editing; J.C.L.: Conceptualization, Methodology, Supervision, Writing - review & editing; S.F.: Conceptualization, Methodology, Supervision, Writing - review & editing; R.L.: Formal analysis, Investigation, Visualization, Writing - review & editing; T.L.: Conceptualization, Methodology, Supervision, Writing - review & editing; T.O.: Conceptualization, Methodology, Supervision, Writing - review & editing; C.M.R.: Resources, Data curation, Writing - review & editing; J.F.B.: Resources, Data curation, Writing - review & editing; L.T.I.: Resources, Data curation, Writing - review & editing. Declaration of Competing Interest We declare no conflicts of interest with this research. Acknowledgements We thank Paul O. Wennberg for contributions, guidance, and support of the Caltech TCCON measurements. We thank James Podolske for contributions and technical support of the AFRC TCCON instrument. Part of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA) [prime contract number 80NM0018D0004]. D.D.R. and J.C.L. were supported by the NASA base grant no. 80NSSC19K0196. S.F. and R.L. have been funded jointly by the NASA grant no. 80NSSC18K1313 (subcontracted from the Universities Space Research Association #05783–01 to Penn State). T.L. was supported by the French research program Make Our Planet Great Again (Project CIUDAD). T.O. was supported by the NASA Carbon Cycle Science Program (grant no. NNX14AM76G) and the Orbiting Carbon Observatory mission (grant no. 80NSSC18K1313). C.M.R. was supported by NASA’s Carbon Cycle and Ecosystems research program (grant no. NNX17AE15G). Sentinel-5 Precursor is a European Space Agency (ESA) mission on behalf of the European Commission (EC). The TROPOMI payload is a joint development by ESA and the Netherlands Space Office (NSO). The Sentinel-5 Precursor ground-segment development has been funded by ESA and with national contributions from the Netherlands, Germany and Belgium. Contains modified Copernicus Sentinel data 2019–2020. Appendix A. Additional figures ![Fig. A.11: Different regions of the LA megacity covered by the OCO-3 target and SAM observations for all four days.](image-url) Borsdorff, T., aan de Brugh, J., Hu, H., Hasekamp, O., Sussmann, R., Rettinger, M., Brie, J., Angevine, W.M., Ahmadov, R., Kim, S.W., Evan, S., McKeen, S.A., Hsie, E.Y., Chilingar, G.V., Endres, B., 2005. Environmental hazards posed by the Los Angeles basin center swath of the same SAM observation mimicking a single nadir track over the LA megacity. The relative surface influence values add up to 100% for the SAM and ≃32% for the single nadir track. Values are gridded at the resolution of the ODIAC emission inventory (1×1 km2).
To Be a Woman in a Man's World: Gender and National Identity in Aidoo's Changes: A Love Story Fawohodie: Ghanaian symbol for independence, freedom and emancipation Stephanie Holmgren # Table of Contents **Introduction** 1 Gender & Gender Identity 3 Gender Theory 3 Gender Identity 4 Nation & National Identity 5 Nation 5 National Identity 5 **Analysis** 8 Gender Identity in Changes 8 National Identity in Changes 14 Gender and Nation in Changes 17 Theoretical background 17 Analysis 21 *Biological reproduction* 21 *Cultural reproduction* 24 *Symbolical reproduction* 26 **Conclusion** 28 **Works Cited** 31 Introduction ‘Leave one man, marry another. Esi, you can. You have got your job. The government gives you a house. You have got your car. You have already got your daughter. You don’t even have to prove you are a woman to any man, old or new. You can pick and choose. But remember, my lady, the best husband you can ever have is he who demands all of you and all of your time. Who is a good man if not the one who eats his wife completely, and pushes her down with a good gulp of alcohol? In our time, the best citizen was the man who swallowed more than one woman, and the more, the better. So our warrior and our kings married more women than the other men in their communities. To prove that they were, by that single move, the best in the land. (109) This quote is taken from Changes: a Love Story, the novel dealt with in this essay, and it represents just one of many contending views on gender identities the novel deals with. It also gives us a hint of a different way of seeing nationality, and that gender relations are closely connected to national identity. In the novel the author Ama Ata Aidoo presents the problem of negotiating gender identity in a postcolonial setting, more precisely in contemporary Ghana. Reading the novel we meet a number of people with different approaches to surviving in a society that has failed to merge tradition and modernity. The novel’s main character, Esi Sekyi, is one of the women who has profited from the modern educational programs that the country’s first president Kwame Nkrumah instigated when he first led the new nation of Ghana to independence in 1954. With a master’s degree in statistics and a well paid government job, Esi tries to combine her career with her role as a wife and mother, but feels trapped by her husband’s expectations on her of subordinance and adherence to traditional norms. In search of independence she leaves her husband and enters into a polygamous marriage with another man, Ali Kondey. Although Esi’s air of independence is what attracts Ali to her, it is still he who is in control in their relationship. Esi is once again subject to a man, and in her quest for independence she ends her romantic relationship with Ali as well. As Esi’s story develops throughout the novel we meet other women and men and are invited to share their struggle to unite competing femininities/masculinities with a sense of national belonging in their young nation. Many of these will be discussed in the following analysis in which I will argue that the formation of gender identity and national identity is intertwined and co-dependent. Through my analysis I aim to show the intersections of the two identities in the novel and with that claim that the novel is a strong plea to people in West Africa, as well as the rest of Africa and the world, to recognize that women have always been active agents of nation building and therefore should have equal right to reap the benefits from that strife, as well as equal power to define national identities as their male fellow citizens have. In this endeavor I will apply theoretical perspectives on gender and nation presented in detail further on in this introduction. To my aid I will also have articles and essays by critics such as Elisabeth, Jane Bryce, Maria Olaussen and Tuzyline Jita Allan who deal with the works of Aidoo. All of the above deal with Changes in their writings, some exclusively and others within the context of her other works. Much of the critical analyses on Aidoo deal with her entire authorship and not single works; and where the focus is on a single work it is usually on her first novel: Our Sister Killjoy: or, Reflections from a Black-Eyed Squint. Why there seems to be a larger critical response on Our Sister Killjoy than on Changes is probably because the prior was published fourteen years earlier and thus has been exposed to criticism much longer. Another reason could be that some critics found Our Sister Killjoy controversial in its “pointed attacks against the Western world” in a way that Changes is not (“Aidoo, Ama Ata.”). Analyses concerned with Aidoo’s authorship as a whole deals with themes ranging from her narrative technique to her inevitable political feminism; with the greater part of the analyses discussing various African feminist issues. It has thus not been an altogether easy task to find critical texts that concern nationalism and national identity in regard to Changes. It has also been somewhat difficult to come across discussions of gender and nation within the context of the novel. The only exception is the text by Willey that I will be using. Although a lot of critical work has been done to explore the women’s conditions in the novel, not much (or even any?) deal with the situation of the men. While the lack of criticism on aspects mentioned above presents a challenge it also gives an opportunity to investigate previously unexplored areas and hopefully add new perspectives on both the novel and the theoretical perspectives used in the analysis. Over all, Aidoo has received mostly positive response to her literary achievements, however she has, according to Tuzyline Jita Allan encountered a good deal of opposition and patronizing attitudes from predominantly African male literary critics and fellow scholars who believe that feminism is a threat to African nationality (171-72). Having given this introduction I will now move on to the theoretical background in which I explore and develop the ideas of gender and nation with their subcategories of gender identity and national identity. With that I will give a basis to the subsequent analysis of Changes. **Gender & Gender Identity** **Gender Theory** The word gender may be found in many different contexts. It may relate to gender in language or simply denote the biological sex of animals or humans, but often it is defined as the social equivalent of biological sex, that is, the practices we engage in in order to express our sex. Forthwith I will use the term ‘gender’ to exclusively denote the social dimension of sex to avoid the confusion that appears when the word is used as a synonym to the term ‘biological sex’. To divide humans into female and male based on biological sex creates a binary structure of opposites. According to Anne Cranny-Francis et al. (1) there is a general agreement that sex is binary and that its two sides, female and male, define each other. This notion is problematized, both by the authors above and by Suzanne J. Kessler and Wendy McKenna in *Gender: An Ethnomethodological Approach*, with the example of children born with both female and male genitals. The example of transsexualism¹ is also put forth in this context (viii). But, all the same, the thought of sex as binary is heavily rooted in Western tradition. According to Toril Moi, the feminist theorist Hélène Cixous claims that the binary pair of male/female is the prototype of all other binary pairs, such as high/low, light/dark, true/false and so on, where the positive half of the pair is associated with the male and the negative with the female. This creates a hierarchical structure in which men are the privileged norm by which everything is measured. This hierarchy creates an unbalance between women and men where the men wield the power (Moi 211). However, this Western male dominated paradigm does not remain uncontested, and its most successful adversary is the feminist movement. ¹ A transsexual person is someone who identifies with the opposite sex instead of with the sex it was assigned at birth (“Transsexualism”). With feminist thought the concept of gender enters into the discourse of relations between the sexes. Cranny-Francis et al. define gender as “a set of meanings that sexes assume in particular societies” (3). These meanings are organized into femininity or masculinity and are attached to biological females and males, assigning certain behavior to a certain sex. **Gender Identity** Gender is thus the practices and behaviors a person uses to identify her/himself as either female or male to her/his surroundings. These notions of femininity and masculinity are, according to social constructionists, learned from the social or cultural environment, and they may vary between different social and cultural contexts. Accordingly, gender is constructed, that is, what is seen as feminine in one culture may be seen as masculine in another. An example of this is the occurrence of men holding hands. In most contemporary Western societies this is seen as something unmasculine, but in countries in the Middle East this is completely acceptable behavior for men. It was also acceptable behavior in 19th century England, which shows that notions of gender also change over time, and consequently puts concepts of innate gender practices and essentialist theories into question (Cranny-Francis et al. 3). This social constructionist perspective is, as already mentioned, a reaction and a resistance against patriarchal dominance and the essentialist notion that gender is fixed and unalterable. Essentialist scholars, on the other hand claim, that gender is a biological production, that is, biological females “produce feminine behaviors” and thus a female identity, and consequently biological males produce masculine identity and behaviors. Accordingly gender is innate and inextricably linked to biological sex. A child is born with an essence of femaleness or maleness; these essences making the different sexes naturally suited to perform different tasks in society. In this manner an essentialist view on gender is an excellent tool to maintain the status quo of the gender dynamics in an unequal male dominated society (Cranny-Francis 3). There are of course many different theories about gender, ranging from essentialist to social constructionist where those in between are more or less influenced by the two poles. The most essentialist theorist would claim that gender is purely a biological production, and the most constructionist theorist would maintain that gender is an entirely social or cultural construction. Judith Butler, who puts forth a theory on gender as performative, is such a theorist. She argues that gender is totally separated from the body and that the production of gender sets in when we label a newborn as a girl or a boy (Pilcher 41). I believe, as Simone de Beauvoir, that “one is not born, but rather becomes, a woman” (qtd. in Cranny-Francis et al. 5), that one learns from society and family how to behave in order to be a “proper” woman or man. I also believe that this is culturally defined, and may even differ within a culture, which leads me to argue that there may be multiple femininities/masculinities at work simultaneously. Nation & National Identity Nation The concept of nation is, as most concepts are, a disputed one. According to Nira Yuval-Davies (15) there are theorists (such as Pierre van den Berghe) that view the nation as a natural phenomenon that stems from the family and kinship relations. In their eyes the family is, in Yuval-Davies’ words, “based on natural sexual divisions of labour, in which men protect the ‘womenandchildren’” (15). By basing the concept of nation on the family the nation “inherits” the value of something natural and, thus something eternal and universal. As an antithesis to the above, Benedict Anderson, according to John McLeod, paints a picture of the nation as an “imagined political community” (qtd. in McLeod 68). It is “imagined” because the members of a nation think that they are a part of a community and that they share “a deep, horizontal comradeship” (qtd. In McLeod 69); they cannot be sure of this since it is not possible for all members of a nation to know or even hear of each other (69). McLeod argues, basing his argument on theories by Ernest Gellner and Benedict Anderson, that nations are “fabrications” and claims that the nation is an idea, a Western construction developed alongside Western capitalism and industrialization (McLeod 68). The idea of the nation was spread through imperialism and colonization, and was later adopted and used for their own purposes by many nationalist movements in the struggle for independence from the colonial powers (75). National Identity I will now revisit Benedict Anderson and his “imagined community”, as it is presented by John McLeod, and from there pursue the thought of national identity as it trails ahead. In Anderson’s “imagined community” the members of the nation depend on the feeling of “deep horizontal comradeship” (69). This emotion of community and belonging is central to the idea of the nation, and has to be reinforced by “narratives, rituals and symbols” in order to form a national identity (69). Notions of a shared history and common origins are also important elements in the forging of a national identity according to McLeod, who here recounts theories by Eric Hobswam (69). McLeod specifically refers to Hobswam’s concept “invention of tradition”, a concept which all nations engage in (70). The national anthem and national flag are examples of such traditions, as well as holidays with reference to events that are considered important to a nation. A shared historical narrative, which is one of the stepping stones to a national identity, is created through presenting one single account of history and then adhering to it (70). In addition to this, Anderson (referred to in McLeod) mentions another central characteristic of a nation’s identity formation, namely language. A national language that everybody understands unifies the nation and helps create a sense of “we-ness” (72). John McLeod presents yet another necessary feature for the formation of national identity: the construction of otherness. The national self is defined in relation to what it is not, that is the other, drawing imaginary borders between the people of the nation and the ones outside (74). In National Identity and Democracy in Africa Mai Palmberg puts forth Anthony Smith’s ideas of national identity which are quite similar to Anderson’s which she also discusses. Both Smith and Anderson declare that national elites are tools used to produce true feelings of national identity (12). The elites are meant to create new symbols out of imagined common roots; they are supposed to be “the inventors of tradition”. Palmberg also calls attention to the fact that the modern nations that were once colonies have the borders they have as a result of colonial gamble for power. When borders were drawn they were drawn with no regard to existing ethnic groups, and communities were often either divided or shattered into pieces, or bundled together with other ethnic groups (11). During the time of oppression under their colonial masters the colonized elite in many colonies found the concept of nation and national identity very useful as a tool to unite the masses in anti-colonial movements. Since many of the colonies were a mishmash of tribes or ethnic groups that often did not feel much loyalty towards each other, the colonial representation of the nation was the only unifying force available (McLeod 75-76). The nationalist movements’ endeavors were now to use the colonizer’s tool to create a national identity strong enough to subvert the colonial power and achieve independence. Léopold Senghor’s and Aimé Césaire’s *Negritude* and Frantz Fanon’s work on national culture were two such endeavors\(^2\) (76). So was the Ghanaian Kwame Nkrumah’s theories on an *African personality*, and I will devote a few lines to describe his philosophy, seeing as this essay deals with a work by a Ghanaian author. Nkrumah and his political party were the leaders of the elite and the dominating voice in the ongoing debate of national identity in Ghana during much of the decolonization and post-independence period until 1966 when Nkrumah was ousted in a coup d’état (7). According to Elizabeth Willey, Aidoo claims that these leaders were the decision makers of the whole community. She also calls in question the elite’s power to define and impute the African Personality on the people (7). Nkrumah’s theories of the African Personality had, as mentioned earlier, its origins in the desire to form a national identity that had roots that ploughed deep in the denigrated soil of African history. He wanted to retell the narrative of history from an African perspective, where Africa has an active history long before European adventurers happened to stumble across the African continent. Nkrumah also advocated the view that Africa used to be a single community and that there could and should be such a thing as a Pan-African political unity. His choice to name the country ‘Ghana’ at independence, instead of the Gold Coast as the former colony had been called, mirrors his Pan-Africanist view of history. The name Ghana was taken from the 11\(^{th}\) and 12\(^{th}\) century empire of Ghana, which was a prosperous and powerful kingdom in what is now Mali and Mauritania and had no connection to the present day Ghana and its people other than being situated on the same continent (7-8). In his strife for African unity and promotion of the African Personality, Nkrumah, overlooked and ignored the diversities within Ghana, both the ones of ethnicity and of gender (9-10). Palmberg acknowledges these diversities and points out several more, among them education. She states that: “education abroad or in an educational system modelled on foreign ideals provide further sets of identities that compete with or colour the formation of national identity” (14). Thus, national identity competes with the very tool meant to promote it, and instead of improving an already confused social situation education with foreign influence exacerbates it. Gender identity and national identity are sometimes also in opposition, just as \(^2\) However, Fanon was critical to the Negritude movement because he “rejected the call for nostalgic celebration of a mythic African past central to Negritude writings”, and because he saw the danger in that “the native intellectual” of the Negritude movement might identify more with the colonizer than the indigenous people he was meant to serve (McLeod 84-85). the others mentioned. However that relationship will be dealt with more deeply later in the analysis since that is my field of study. Having introduced the two theoretical perspectives of my study I will now move on to the analysis. In the two first parts, *Gender Identity in Changes* and *National Identity* *in Changes*, I deal with how the two perspectives are represented in the novel respectively. In the third and last part, *Gender and Nation in Changes*, I explain how the two identities intersect, both in theory and in the novel. **Analysis** *Gender Identity in Changes* The novel deals with many different representations of gender identity, many different femininities and masculinities which either endorse traditional values or try to negotiate traditional and modern standards into a new equitable approach. It is not possible to analyze each one of these representations in depth in this limited space, I will therefore touch briefly on some and analyze others more deeply while others have to be left without discussion. I will examine the different views of femininity represented and how they interact with each other but also how they interact with notions of masculinity put forth in the novel. The femininity represented by Esi stands out in comparison to other notions of femininity put forth by the other characters. Formed by an education with influences that do not seem to agree with the society she lives in she is forced to compromise her ideals with reality. Her ideal is to be able to have a career and a family without being looked upon as less of a woman or an unfit mother just because she brings work home and travels a lot. Clearly her ideals are not shared by her first husband, Oko, with whom she has constant fights concerning her work and her role as a wife. Although he loves her very much he cannot handle her independence in relation to him. He wants her to spend more time at home with him and their daughter and to be more like a traditional woman, that is, a woman whose first priority is to take care of the household and to serve her husband and family. As Esi does not fulfill these requirements Oko feels neglected and also hurt because his love for her is unrequited. Contemplating their marriage Oko is thinking: “…what had he got out of it? Little. Nothing. No affection. Not even plain warmth. Nothing except one little daughter!...He wanted other children…a boy if possible” (8). According to him “Esi definitely [puts] her career well above any duties she [owes] as a wife” and this makes him look bad (8). He complains to Esi that her behavior makes his friends laugh at him for not being man enough to control his woman. However, I believe the main reason for his discontentedness is due to the fact that he is unclear about his role in their relationship. He has been taught that it is the man who is head of the house and who is the main, if not sole, breadwinner of the family. In his and Esi’s relationship she earns more than him and the house they live in is a fringe benefit from Esi’s job. From his perspective Esi must seem like an usurper trying to claim the power rightfully belonging to him, the male; and in an attempt to regain dominance and self-respect he rapes her. The fact that Esi defines Oko’s advance as marital rape instead of thinking of it as him exercising his right as a husband suggests an unsubmissive spirit. While resenting Oko’s assault she also ponders the fact that there is no word equivalent to “marital rape” in her native language, nor in any other African language she knows of. She thus identifies a rift between her world and the world of her “mothers”. I will return to this rift and discuss it further later in the analysis. However, choosing to call Oko’s action a rape is critical point to Esi’s because in choosing to do so she takes an active approach towards a new and improved understanding her own femininity. As Esi divorces Oko she continues her quest to live a full life and ends up in a relationship with Ali, a man who is already married. Choosing to enter a relationship with a married man indicates a negotiation from Esi’s point of view. She has already tried marriage but it failed on the grounds of her husband demanding too much of her time. However, being divorced and having no man in her life becomes too lonely. Esi’s solution is thus to have a extramarital relationship thinking that Ali will demand less of her than Oko did, since Ali already has a wife and children to devote his time to. Esi is finally free to dispose of her time as she wishes, and in control of her life. But she soon realizes that her relationship with Ali is under his control; he decides when to come to her house and when to go home to his wife and children. Ali also divulges a desire to control Esi by asking her to marry him, to become his second wife, instead of remaining his mistress. In this instance we can see a relapse to a traditionalist pattern, or rather a sexist pattern, when Ali, though admiring her independence, wants to mark Esi as occupied territory and claim ownership of her. Answering Ali’s proposal with a “Must I?”, Esi reveals her ambivalence about accepting it (86). However, she does accept it despite her own apprehensions of looming complications as well as her mother’s and grandmother’s advice against the marriage. This decision seems to go directly contrary to Esi’s independence and the only clues we get to why she agrees to marry Ali is that the idea of a polygamous marriage fascinates her greatly, and that she likes the fact that he is an only child with no interfering relatives near by. The solution to the riddle might lie in Esi’s almost desperate proclamation to Okopuya that “monogamy is so stifling” (98). By choosing a form of marriage that resembles a “real” (that is, monogamous) marriage the least she hopes to avoid some of the unpleasantries she had with Oko and his, in her eyes, interfering family. Another explanation of her consent to the marriage may simply be that she is in love with Ali, and that she is afraid that he will not want to continue their relationship unless they marry. Whatever the case may be Esi is compromising her ideal of autonomy nonetheless by agreeing to the marriage, because her first choice would have been to stay unmarried. Some of the reasons to why she, and her likes, cannot stay unmarried will be dealt with further ahead in the analysis. Upon hearing of Esi divorcing Oko her mother and grandmother are wondering whether Esi has gone completely crazy. To them it is pure madness to have let go of a good husband such as Oko. Esi’s argument that he demanded too much of her time is stricken down by her grandmother, Nana, retorting: “…doesn’t a woman’s time belong to a man? My lady Silk, that one is a very new and golden reason for leaving a man, if ever there was one …. The best husband you can ever have is he who demands all of you and all of your time” (109). When the question of Esi becoming Ali’s second wife comes up she questions the idea of exchanging one man for another. As far as she is concerned Esi had the best husband she could ever have, and if he did not satisfy her no man ever will. Esi’s mother, Ena, does not like Esi’s divorce or marriage to Ali at all on the grounds that with such an education as Esi’s she deserves better than being somebody’s second wife. Both Ena and Nana were raised in societies where polygamy was common and are thus used to the concept. They are also aware of the hierarchies in such a society, hierarchies that Esi seems oblivious of. To Esi’s mother her choice to trade a husband of her own for a husband to share is a step down in that hierarchy. Ena’s dislike does not emanate in the fact that it is a polygamous marriage, but that Esi is the second wife and not the first. In her view the first wife is the “proper” wife, and in renouncing that place she is also renouncing the power it entails to be the senior wife. For Esi this is a deliberate choice, because in renouncing that power she also believes she avoids the obligations that accompany that role. She believes that Fusena, Ali’s first wife, will fill the needs Ali has that Esi did not want to fill for Oko, and that she, Esi, can get away with being the “bonus wife”. What she does not take into consideration is the fact that Ali feels somehow indebted to Fusena for sacrificing her career as a teacher to stay home while Ali educated himself, acquiring one degree after another. Besides the feeling of indebtedness Ali loves Fusena and tries not to “hurt her deliberately” by flaunting his love affairs or acting in a manner that would “leave her feelings unnecessary bruised” (78). The obligations Ali has as a husband and father thus compete with time he spends at work and with Esi. In this lottery, where the prize is Ali’s loyalty and presence, Esi inevitably draws the shortest straw. As mentioned earlier Esi is at first not at all discontented with the fact that Ali is not with her all the time. In fact, in the following passage her feelings seem contrary: “…her basic hopes for marrying a man like Ali had been fulfilled. Ali was not on her back every one of every twenty-four hours of every day. In fact, he was hardly ever near her at all. In that sense she was extremely free and extremely contented” (137-38). However, as time passes, a feeling of dissatisfaction comes stealing up on Esi. She is lonely and she starts examining the nature of her marriage to Ali. The fact that she is in love with him (with Oko she had felt only gratitude) complicates her situation further. Tuzyline Jita Allan writes: “As Esi gets entangled in love, her sturdy independence begins to turn flabby, leaving her enervated almost to the point of a nervous breakdown” (183). When Esi hears of Ali’s new secretary and his habit of driving her home every day she does not like it at all. While Ali’s phone calls and visits grow sparse his gifts and souvenirs for Esi come more frequently. After three years of marriage, a marriage of constant waiting and uncertainty when to expect Ali, Esi is finally fed up with it. She is fed up with receiving gifts as substitutes for Ali’s presence and thus ends their relationship, although they formally stay married. Esi concludes that she believes Ali loves her, in his own way, but that “his fashion of loving [has] proved quite inadequate for her” (Aidoo 166). As stated in the confession/apology preceding the first page of the novel, Esi is “a somewhat privileged young woman” (n. pag.). Although this short introductory paragraph is without a doubt highly ironic the previously quoted phrase is essentially true. Compared to many of her fellow “countrywomen” Esi is indeed privileged. It is only when her life is put in juxtaposition to the life of a man that she seems much less privileged all of a sudden. I have briefly dealt with some of the women in Esi’s vicinity who think and act differently than her, those being Nana, Ena and Fusena. What unites these women is that they conform to the conventional way of living, accepting an inferior position in relation to their husbands and other men. They are not so much interested in altering their position towards men as they are in creating a position for themselves in relation to other women, because they feel, unlike Esi, that it is a lost cause. One of the beauties with the novel is that these women are not depicted as primitive subdued women that uphold ancient values for their own sake, but as intelligent women conforming (sometimes with hidden resistance) to a male dominated world in order to survive (Olaussen 65). Most of them do not have the means to break free, for as Nana intimates to Esi, there are certain variables needed in order to escape male dominion. “You have got your job. The government gives you a house. You have got your car. You have already got your daughter. You don’t even have to prove you are a woman to any man, old or new. You can pick and choose” (Aidoo 109). Esi’s independence is not granted any of the women mentioned above, mostly because they do not have the same degree of financial freedom she has, but it seems as if they also lack the desire or courage to effectuate a change in their situation. Or perhaps what is mistaken for lack of courage is really a sense of pragmatism. Maybe these women just have a different approach than Esi. As Maria Olaussen writes “Their strength lies in their resignation and their power in their cynicism that makes it possible for them to pay lip service to high ideals while gaining what they may from any form of double morality and duplicity” (Olaussen 65). This statement is seconded by Fusena’s relatives realizing that “it [is] a man’s world. You only [survive] if you [know] how to live in it as a woman.” (Aidoo 107). In this quote it is made clear that women and men have different roles in society, and that it is essential to now how to play the part. It is also shows the advantage of power men have over women, the men being the ones who define the world. A character I have left without discussion thus far is Esi’s best friend Okopuya with whom Esi discusses the demands on and possibilities available to the modern African working woman. My choice to deal with Okopuya so late in the analysis does not reflect any lack of importance; on the contrary she is central in the novel. Okopuya’s function is to be somewhat of a mediator between rebellion and conformity; she stands somewhere in between Esi and Fusena in that respect. Just as Esi and Fusena, Okopuya is an educated woman. She has worked as a state registered nurse and midwife for fifteen years and contributes to the household income. Despite this she chooses a different path in the encounter with marriage and the expectations of it compared to the two other women. While Fusena very reluctantly conforms to a more conventional and traditional lifestyle in which her husband wields the power, and Esi decides to rather stand outside of marriage than to conform, Okopuya accepts the rules and roles of marriage to some extent but also, in her own way, tries to resist them. Okopuya’s role towards Esi is somewhat double-faced. While agreeing with Esi in theory on the topics of their discussions, that is, marriage, divorce, motherhood, independence and career ambitions, in practice Okopuya is more realistic and pragmatic. When Esi tells her about the divorce Okopuya is as shocked as Esi’s mothers concerning her reasons for the break-up, but mostly she is shocked by Esi’s childishness. When Esi complains about Oko craving too much of her attention Okopuya asks her to be realistic and realize that it is normal for a man to want to be with the woman he loves as much as possible, even to the extent that he wants her to change her job. As they go on to talk about women’s independence and intelligence and men’s demands on them Okopuya says: “men are not really interested in a woman’s independence or her intelligence. The few who claim they like intelligent and active women are also interested in having such women permanently in their beds and in their kitchens” (45). They both agree that this is a contradiction and feels the hopelessness of the situation. The choice for the educated intelligent woman is either to succumb to the demands of marriage and motherhood, or to stay alone. After Esi’s assertion that she will stay alone unless she meets a man who will accept her lifestyle, Okopuya is once again the realistic one and retorts: “You just can’t have everything your way, and not expect to be lonely, at least some of the time….No matter what anybody says, we can’t have it all. Not if you are a woman. Not yet” (49). The passages above show a side of Okopuya that is complying with, yet not agreeing with the conventional way of thinking. However, as I mentioned earlier, she also acts out some kind of resistance, although she chooses her battles. When, at an early stage in the novel, we get to know Okopuya we learn that, after the birth of her fourth child, she decides that that is enough and has a tubal ligation. According to Juliana Makuchi Nfah-Abbenyi this operation is something very few African women would willingly submit themselves to whether they are educated or not. The reason is that African women often view their womanhood as almost interchangeable with motherhood, and sterilization would thus mean a loss of femaleness (285). This conflation of motherhood and womanhood is an excellent example of how gender is constructed on the basis of specific tasks assigned to women in a society. Despite this view on femininity, Okopuya goes through with the operation, and in this way shows great independence from existing notions of gender. Another instance of deliberate resistance is Okopuya’s constant quarrels with Kubi about the car. According to Olaussen sexuality and mobility are connected. She writes: “the men in control of the cars are usually also the ones who control the women’s sexuality” (67). Throughout the novel cars represent freedom of movement for the women, and, to take Olaussen’s view on it, cars would thus also represent sexual freedom. Whether or not this is the case for Okopuya, it is quite clear that by buying Esi’s old car when she gets a new one from Ali she gains some kind of autonomy, and takes control over yet another part of her life. In this first part of the analysis I have established that there are several types of gender identities at work at the same time in Ghanaian society. I have also exposed the inequalities within this society where men wield the power and exercise control over women; it is in deed “a man’s world” (Aidoo 107). As women like Esi and Okopuya resist male control and try to form new ideas of femininity they are confronted with a refusal to accept these from both men and other women. Another thing that becomes clear is that the struggle for female autonomy is not a one (wo)man enterprise, but a task for a whole nation. **National Identity in Changes** An analysis of national identity in this novel is by necessity of a somewhat different kind than the one on gender identity that we just have dealt with. This is due to the fact that the theme of national identity is treated in a lesser extent and much less obvious in the novel than that of gender. I will therefore focus on Esi and the fact that education plays an important part in her life and the lives of so many other Ghanaians and Africans. I will also deal with Ali and his sense of belonging in regards to nationality. Some space will also be devoted to how ethnical identities of people, such as Fusena and Okopuya, sometimes stand in opposition to national identities. As I have mentioned earlier, Benedict Anderson and other theorists on national identity have claimed that a nation is built by its intellectual elite, relying on them to negotiate traditional and modern values and shape new national ideals. In post-colonial nations the intellectuals are educated in an educational system built up by their former colonizers. Based on different ideas and values than those of the indigenous peoples this system brings a foreign influence to the ones undergoing this education, and as Esi they become “fundamentally changed by [their] education” (109). For Esi this is a problem that turns into a crisis. Being an intellectual it is her duty to “invent tradition”, but as someone having been fundamentally changed by her education she finds no bond to her roots strong enough to do this. That this bond is weakened becomes painfully clear to her when she overhears her mother and grandmother talking about her and her impending marriage to Ali. The conversation between them reveals a closeness and the following quote makes Esi’s feelings clear to us: “She could never be as close to her mother as her mother was to her grandmother. Never, never, never. And she knew why” (114). She continues with asking herself: “Why had they sent her to school? What had they hoped to gain from it? What had they hoped she would gain from it? Who had produced the educational system that had produced her sort?” (114). Further on we learn that entering into the world of education had meant for her to be sent to one boarding school after another and losing touch with her mother and her first language. Thus she is “only equipped to go and roam in strange and foreign lands with no hope of ever meaningfully re-entering her mother’s world” (114). The bond between herself and her origin being cut presents her with difficulties to perform her task as nation builder because the gap between her schooling and tradition is so great. As Esi realizes that “all this [is] too high a price to pay to achieve the dangerous confusion she [is] now in and the country [is] now in”, she also understands that she alone will not come up with the answers to all the “serious personal, and not so personal, questions” this confusion gives rise to and hopes that “a whole people [will] soon have answers for them” (115). Further more I have discussed in this essay the fact that most post-colonial nations consist of more than one ethnic group and that ethnic identity often compete with national identity. In an endeavor to unite Ghana, Kwame Nkrumah advocated a stance towards national identity including his philosophy on the African Personality with which he meant to deemphasize the ethnic differences within the country. That the college where Ali and Fusena study before they get married bears traces of this endeavor becomes clear in the following passage: “The college was one of those that had been almost deliberately placed in confluent towns of Ghana to attract aspiring teachers from the dominant ethnic groups in equal proportions” (57). However, the attempt to make the students socialize over the ethnical lines is not very successful, neither at the campus in Atebubu where Ali and Fusena are at, nor at the others. The fact that most of the students keep to their ethnic groups indicates that the ethnical affiliation is stronger than the sense of being a Ghanaian, or an African for that matter. Another sign that might lead us to conclude that ethnicity has precedence of national identity is that both Fusena and Ali are referred to as belonging to a part of the country or the sub-continent by reference to the vegetation. Ali is called a “man from the Grasslands” by Nana (111), and when Fusena feels displaced in rainy London she thinks of herself as a “daughter of the dry savannahs” (66). Even Okopuya’s worries about Kubi’s safety may be seen as an expression of the importance ethnical affiliation has in the novel. Her husband’s safety is vital to her because he is her “excuse” for living in Accra, that is, in his part of the country. She has lived away from her own region since she was about fourteen, always living among Kubi’s people. Still, without Kubi she does not really belong in his part of the country, and she is as good as a stranger in her own part. If Kubi would die she would have to stay in the city, “a native of nowhere” (56). Hence we may conclude that a sense of belonging is important, and to Okopuya the feeling of belonging is primarily connected to being a part of a geographical or ethnical group, not to a nation. Ali is somewhat of a puzzle in regard to nationality and national identity. With a tradesman as a father he has traveled the whole sub-continent of West Africa as a child, and as an adult he continues to do so through his own business. Born and brought up in Bamako he decides that this is home, and: having settled the question for the convenience of his heart, he had proceeded to claim the entire Guinea Coast, its hinterland and the Sub-Sahel for his own. In any case, since he had learned that his grandfather’s house had stood on the exact spot where Burkina Faso, Ghana and Togo met, he had assumed the nationalities of Ghana, Benin, Côte d’Ivoire, Burkina Faso, Niger, Mali, Nigeria and Togo. Naturally, he carried a passport to prove the genuineness of each (23-24). Ali thus has the freedom to choose which country to belong to, and what nationality to assume, and somehow the idea of national identity does not seem important to him. In the quote above he decides that Bamako is home, not Mali. This decision is based on the fact that Bamako is the place he was born, but also because it is where Mma Djanuma, his aunt who raised him, lives. In this manner, his feeling of belonging is first and foremost to his family and the city he was born in, not to the nation. As for regional borders and nation lines he ignores them and goes on “to claim the entire Guinea Coast, its hinterland and the Sub-Sahel for his own” (23). In her article, Jane Bryce suggest that Ali’s character might question “the whole idea of nation, of ethnic affiliation, identity tied to place, home, country” (n. pag.). This thought resembles Nkrumah’s pan-Africanist aspirations, although he considers the African continent to have been a single community before colonial influence and hence he must believe in some kind of continental identity. Elizabeth Willey holds the view that Aidoo, through the novel, maintains Nkrumah’s idea that “the answer to ideological disruption in African societies lies in the community not the individual”, which indicates that Bryce might be right (24). However, one thing Ali promises himself early in his traveling life is that he will always live in the zongo of the cities he stays in. The reason Ali gives himself for this promise is that the zongo is the only place in the southern cities where he can be sure to get the kind of food specific to the region where he grew up. Although this seems a simple enough explanation, I believe there is more to his wish to live in the zongo than this. Being brought up a Muslim, Ali feels at home in the zongo surrounded with Muslim culture; this is --- 3 Bamako is the capital of Mali. 4 Zongo is a “West African term for a ghetto of northern peoples in southern cities. Most people who live in zongos are presumed to be Islamic” (Aidoo 167). his home away from home. Therefore the total disclaim from all kind of cultural affiliation we seem to get from Ali in his claim to be a West African has a hollow ring to it. Although he wants to think of himself as a man of the world, a collector of nationalities, he is not a collector of cultures. He is still undeniably marked by his own culture, and does not wish to relieve himself of it or add to it from other cultures. This does not entirely negate the question posed by Bryce when she wonders if not Ali’s character rebels against the concept of identity connected to nation, ethnicity and geography, but neither does this affirm it. He does in deed mock the notion of nation and does not show any signs of national identity towards any one of his nations, nor does he contribute to the formation of a Ghanaian national identity or any other national identity for that matter. He is a free-floating collector who collects nationalities as well as women, but does not commit very strongly to neither of the categories. At the same time he cares about his Muslim heritage, and acknowledges his feeling of connectedness to the peoples of the zongos. However, the fact that Ali’s house is located in the very outskirts of Nima, the zongo of Accra, is symptomatic of Ali’s unwillingness to commit, even to his own culture. As he picks and chooses which boundaries and traditions to ignore and which to uphold, Ali remains an enigma when it comes to national identity. With this section of the analysis I have brought to light that there seems to be a problem with the concept of national identity with regards to once colonized nations such as Ghana. While we see how attempts to unite the different ethnicities in the country are made by the leaders, as with the location of the teacher’s training college of Ali and Fusena; we also see how they miserably fail. I have also shown the difficulty it entails for Esi to be an educated woman and a Ghanaian woman at that, a difficulty bringing with it a state of confusion about her role in the nation building process. Meanwhile, Ali has the freedom to choose whichever national identity he likes. There is thus a difference between the possibilities women and men have to engage in the formation of a national identity. **Gender and Nation in Changes** **Theoretical background** I will now deal with the intersection of gender identity and national identity, and shed some light on how these two fields overlap and constitute each other. The fact that there is an intersection of gender identity and national identity is quite obvious, since most, if not all, people have been assigned both a gender and a nationality. These two aspects of identity are only part of what constitutes a person’s full identity, but they are none the less important. As mentioned in earlier sections of this essay gender identity is constituted largely by cultural norms of femininity/masculinity. As these norms are repeated they reproduce culturally specific norms and behaviors which help create and recreate the identity of the entire nation (Mayer 5). With the help of Otto Bauer, Tamar Mayer puts forth the idea that “the nation is bound up with ‘ego’”, i.e. the “ego” of a single person is inseparable from the “ego” of the nation the person belongs to. The “ego” of the nation helps the individual create her/his own identity. With this she explains the male hegemony in the discourse and practice of nation building, since the concept of nation was produced by heterosexual males. Their “egos” constructed the norms of the nation (6). The two concepts of gender and nation have both been used as repressive tools to subjugate women by denying diversity in gender identities and national identities according to Tamar Mayer (1). She also claims that the concept of nation is gendered, i.e. women and men tend to have different roles in the production and reproduction of a nation, and that “through control over reproduction, sexuality and the means of representation the authority to define the nation lies mainly with men” (2). In this way men become the active agents and protectors of the nation, while women reproduce it, biologically, culturally and symbolically (Mayer 6, Yuval-Davis 2). Nira Yuval-Davis similarly claims that the reproduction of a nation is gendered. She questions the idea that national identities are reproduced by bureaucrats and intellectual elites only and claims that women “reproduce nations, biologically, culturally and symbolically” (2). She brings forth that many scholars in the field of nationalism and nation building are blind to, or at least fail to acknowledge, the fact that national identity is reproduced both in the domestic sphere (which is traditionally assigned to women) and the public sphere (which is conventionally occupied by men) (1). She even leans towards professing that women are the sole reproducers of the nation, but in the end leaves that with a question mark (2). I believe what she is reaching for with that claim is to reveal that women actually are a part of reproducing national identity, and because of that women should be acknowledged as active agents and given equal power in constructing nations and reaping the benefits from them. This scenario has not been a reality, and is still not fully accomplished in most parts of the world. Yuval-Davis shows this by pointing to several areas where women and nation meet, in which women are used as tools of patriarchy, reproducing male ideals and male “egos”. Some of these areas I have mentioned in passing, namely the areas of biological, cultural and symbolical reproduction, and below I will explain them briefly. Writing about women as biological reproducers of the nation Yuval-Davis, according to McLeod, refers to the fact that it is women who give birth to new members of the national collective. This fact has been used to make women believe that it is their duty to produce children to ensure the nation’s survival (McLeod 116) and to secure the ethnic purity of the nation, controlling it by marriage and procreation between women and men who both belong to the proper ethnic group (Yuval-Davis 22, McLeod 116). Women also function as cultural reproducers by way of being “the primary educators” of the nation’s children and responsible for teaching them traditional norms and values (McLeod 116). Women are thus cultural transmitters who reproduce a specific set of norms preferred by the “ego” of the nation. Lastly, women serve as symbolical reproducers, or as Armstrong puts it “border guards” (qtd. in Yuval-Davis 23) between “us” and “them”, that is, the nation and “the other”. The division between categories is upheld by symbols that are supposed to signify the culture that is being reproduced. Such symbols are closely connected to specific cultural codes, ways of dressing and culturally specific behavior, but also to notions of femininity/masculinity and gendered relations of power adhered to in the nation (23). As symbolical reproducers women are often iconized as the image of the nation and, as I mentioned earlier, they are represented as passive and in need of heroic men to protect them and defend their honor (McLeod 114). However, it is of importance to note that even though women have been seen, and to a large extent still are seen, as passive reproducers and not as active agents of the nation and creation of national identity, women are producers of cultural and moral codes which are defended against those outside the cultural collective. They also partake in exerting power and control over “the Other” (Mayer 6). Yuval-Davis also holds the view that women in some cases wield a similar power over fellow women and people outside the collective as men wield over them. She argues that it is especially older women that are given the power to decide what is to be considered appropriate behavior or deviant behavior (Yuval-Davis 37). In order to be classified as “the other” it is enough to fail to live up to the standards set up by the collective. When it comes to gender women are the ones represented as “the other” because of the male hegemony in most societies, and thus “feminine” and “other” have in some respects become mutually exchangeable. Consequently, what fails to live up to male standards is considered feminine. This conflation of feminine and “the other” has metastasized to the relationship between imperial powers and their colonies. The colonizing nation is in power and therefore the one who sets the standards and puts up the normative fence that keeps the colonized people at a distance, maintaining their “otherness”, assigning them femininity. The connection between femininity and the colonized is explained by Ania Loomba with this passage quoted from Helen Carr: in the language of colonialism, non-Europeans occupy the same symbolic space as women. Both are seen as part of nature, not culture, and with the same ambivalence: either they are ripe for government, passive, child-like, unsophisticated, needing leadership and guidance, described always in terms of lack – no initiative, no intellectual power, no perseverance; or on the other hand, they are outside society, dangerous, treacherous, emotional, inconstant, wild, threatening, fickle, sexually aberrant, irrational, near animal, lascivious, disruptive, evil, unpredictable. (159) In the passage above colonized and women are said to “occupy the same symbolic space”; they are both declared “the other” in relation to something, namely the male norm. For colonized men this “otherness” has sometimes meant a depiction of themselves as men with deviant sexuality, and with all the lusts and forbidden desires that the colonizers tried to repress within themselves. That which was unbecoming to a man was attributed to the colonized (Loomba 155-156). In the same spirit colonized women were also depicted as lascivious and full of promise for the colonizing male’s sexual fantasies (McLeod 175), that is, the opposite to the “goddess” or “angel” the colonizer kept in his own home. The feminization and marginalization of colonized men had as one consequence out of several the effect that they became more tyrannical at home, that is, to their women (Loomba 168). According to McLeod, Kirsten Holst Petersen and Anna Rutherford thus claim that women have undergone a double colonization. They suggest that women are colonized “by colonialist realities and representations, and by patriarchal ones too” (McLeod 175), that is, women have been suppressed by being assigned certain gender identities shaped both by colonial influence and by patriarchal dominance. In both colonial and postcolonial theories on nationalism and national identity women have been portrayed as “the moral barometers of a nation” to use the words of Willey, instead of being seen as the “active participants in the nation” they really are (3). Analysis In once colonized countries such as Ghana, colonial powers have influenced national identity and thus also gender identity. By reproducing the notion of nation and national identity, ideas of foreign gender identities are also reproduced and incorporated in a new set of gender roles. That is why resistance to male dominance has to include opposition to existing norms of national identity. But before I begin to describe how the opposition against the male hegemony in both gender identities and national identities shows itself in Changes, I will find and analyze examples in the novel of where these two areas intersect. In order to locate these intersections I will use Nira Yuval-Davis’ previously mentioned classification of women as biological, cultural and symbolical reproducers of the nation and national identity. Although this perspective inevitably has its focus on women it will undoubtedly reveal a lot about men as well. In the following sections I will describe how Yuval-Davis’ three areas of intersection are represented in the novel. I will also deal with the resistance showed by various characters to each of the areas, in order to analyze how this resistance and the ‘dangerous confusion’ Esi speaks of, affect the various people involved. Biological reproduction As biological reproducers women are expected to marry and have children. This view is endorsed by several of the novel’s characters, for example Fusena’s mothers who scolds her harshly when she refuses to marry the “alhaji” at the age of twenty-six but is contented later when she marries Ali. The mothers finds it unbearably stupid to turn down such a rich and prominent man as the “alhaji”, especially as Fusena will no doubt have problems finding a man who would have her at her age. The questions her mother poses to the “mallam” shows the gravity these matters bear for her. “Was [Fusena] ever going to [get married]?....when that time comes, would she not be too old to have children?....How many children would she have?” (59). The fact that both Ali’s and Fusena’s families insist on that --- 5 Alhaji: “is a term of respect used to address a Muslim man who has completed one of the Five Pillars of Islam by going on the Hajj, or religious pilgrimage to Mecca” (“Alhaji”). 6 Mallam: I cannot find any definition of the word, but judging from the context it appears in in the novel I would interpret the term as a West African word for mullah. A mullah is part of the Islamic clergy, the equivalent of a Christian priest (“Mullah”). In any case it seems like a mallam is some kind of a holy and/or wise man. Fusena should become pregnant before Ali leaves for England also indicates the importance of child bearing. Nana’s attitude towards marriage does also advocate the view that the first and foremost duty of women is to procreate. This is evident in Nana’s answer to Esi’s question about what some of the reasons for marrying are. She says: “Esi we know that we all marry to have children…” (42). In this conversation between grandmother and granddaughter Esi questions Nana and the essentiality of marriage when she replies that “[c]hildren can be born to people who are not married” (42). This way Esi takes procreation out of the realm of marriage, and thus implies that marriage is old-fashioned and unnecessary. Nana’s second argument in favor of marriage is that it is a means of increasing the amount of people to share a sense of belonging with. This argument resembles Yuval-Davis’ claim that production of children is a way to ensure the survival of the nation, and can hence be seen as a nationalistic argument. It also goes hand in hand with Benedict Anderson’s thoughts on imagined communities, which share a sense of belonging, as it creates national identity. Therefore, in questioning Nana’s view of marriage, Esi is also challenging her view of the nation. When Esi and Okopuya are at the Hotel Twentieth Century talking about the impossible situation for single women, they swiftly identify the oppressive mechanism in the fact that single women are invisible in their society. As women situated outside of marriage single women cannot/are not allowed to procreate, and are thus not fulfilling their duties as biological reproducers. Okopuya expresses this well as she says: “…our societies have had no patience with the unmarried woman. People thought her single state was an insult to the glorious manhood of our men” (48). As she continues she describes the circumstances that put Esi in the predicament of not being able to stay unmarried after her divorce from Oko. Here Esi and Okopuya fill in each other’s sentences speaking of how people treat the unmarried woman. ‘So they put as much pressure as possible on her – ’ ‘ – until she gave in and married or remarried, or went back to her former husband.’ ‘And of course if nothing cured her they ostracised her and drove her crazy.’ ‘And then soon enough, she died of shame, loneliness and heartbreak.’ (48) A woman’s alternative to the role of biological reproducer is thereby nonexistent. As I have mentioned earlier in this analysis Nfah-Abbenyi claims that African women’s sense of womanhood is contingent on motherhood. The example of Okopuya and her choice to have a tubal ligation, which I have dealt with earlier, is still valid and worth mentioning in this context. Her choice is a deliberate resistance to the simplistic view of women’s role as biological reproducers. She firmly believes that she is no less of a woman despite the fact that she no longer can have children. Just as Okopuya claims that their society has had no patience with unmarried women Oko shows a lack of patience towards Esi when she does not fulfill her role as child bearer. He feels that Esi neglects her duties as a wife when she decides to use contraceptives. He is eagerly supported by his mother and sisters who suggest that Oko should “make some other children ‘outside’”, that is, outside his and Esi’s marriage (8). But no matter how much Oko tries to persuade Esi to give up “those dreadful birth control things: pills, loops or whatever” she will not part with the sense of autonomy it gives her to be in control of her own body (8). And that is why Oko’s violation is so severe. For women like Nana and Ena, Oko’s actions that morning when he raped Esi do not seem very grave. In their minds Oko was in his full right to do what he did. “Sex is something a husband claims from his wife as his right. Any time. And at his convenience” (12). But for Esi with her “new and foolish ideas”, which Fusena’s mother calls “a sickness that so many educated people seem to suffer permanently from”, the rape is a violation on her self-determination and independence in a way her mothers would never understand (60). There is thus, as I have mentioned before, a rift between Esi’s world and the world of her mothers, or the greater part of Esi’s contemporary society for that matter. This rift is being epitomized in Esi’s realization that the term she uses to describe Oko’s violation, that is “marital rape”, does not exist in her native language or any other African language she knows of. In her choice to name the incident rape she deliberately takes a step away from her mothers’ world and moves towards an alternative world view in which, as Bryce puts it, “[t]raditional rules have been superseded, but not replaced” (n. pag.). With this action Esi has freed herself from the restraints of an oppressive role as merely a biological reproducer, but what she becomes conscious of throughout the novel is that there are no new roles ready-made to put on for her. Esi’s liberation consequently results in confusion of how to define herself and how to create a new form of female identity, since she is counteracted in this task by both women and men. **Cultural reproduction** To act as the primary educators of children is another task that has been given to women, and this is what makes Yuval-Davis define them as cultural reproducers. This role is closely connected to the function of biological reproducer; women produce children whom they then stay at home to raise. Here, as well as in the previous section on biology, the roles are used as tools to construct national identity. This is done by stressing, as Nana does, that we marry to produce children and to give these a home in order “to help them grow up well”, that is, to foster them to become good citizens of the nation (42). That this is a role that should be assigned to women seems to be quite obvious to among others Ali. He gladly goes off to England to study, leaving Fusena in Ghana to give birth to and to raise their first child. It is only after three years has passed that he sends for her and their son. As Fusena comes to London and becomes a housewife, Ali does not reflect on that she might want more. To him it goes without saying that she will give birth to his children and be at home to take care of the household. Fusena accepts this, but to a limited extent. After spending some time in London, isolated in their home doing housework and caring for their children, she contemplates her situation. She realizes that she, by marrying Ali has traded a friend for a husband. By agreeing to marry Ali she gives up her independence and her ability to make decisions about her own life, but this is something she realizes only when it is too late. This realization is shown in the passage below. …there was no chance of her getting back her friend [Ali] if she left or divorced Ali the husband. She would only have an estranged husband….she kept telling herself that given the position of women in society, she would rather be married than not, and rather to Ali than anyone else. (66-67) Just as Esi and Okopuya, Fusena is painfully aware of the inequalities in marriage and society as a whole, but unlike Esi, and to some extent Okopuya, she does not take action to fight them. She stays married to Ali, becomes the perfect housewife, and in exchange Ali gives her a kiosk to manage. As most West African women Fusena has been brought up to work and the kiosk is Ali’s concession to her wish to go back to work after staying at home for five years bringing up children and minding the household. Ali’s reason for buying her a kiosk instead of letting her go back to teaching is because it is “a more lucrative job [she] could do and still have time to look after the children” (67). This is an outstanding example of how Ali, and with him the major part of society, limits the women and prevents them from moving out of the domestic sphere. Ali has no problem with having Fusena work, as long as she performs her duties as wife and mother as well, that is, acts as a biological and cultural reproducer. The same applies for Oko in his relationship with Esi. He knows when he marries her that she will have a high education and be well suited for a prominent job. What he probably does not expect is that Esi will not give up her career to have children and play house with him. As for Esi, she most likely believes, at least in the beginning of her marriage, that Oko shares her ideals of a modern marriage and that she can have both a career and a family. As we know she proves to be wrong. Oko demands that her time should be spent more on their home and less on her work. Just as he feels that Esi does not fulfill her duties as a wife when she uses contraceptives he also feels that she neglects her role as a mother and primary educator when she is away from the house so much. In a sense Oko is right, and that is part of Esi’s sacrifice to reach a higher, and to her an acceptable, level of autonomy. Another sacrifice she is forced to make is the one of leaving her daughter Ogyaanowa to live with Oko’s mother. Thus the repressive system forces Esi to give up her daughter in order for her to be able to compete with her male colleagues in her work life. Esi is by no means alone with this problem, and Okopuya makes sure to remind her of that when she complains about how her male colleagues are given promotions while she is passed over time after time. Okopuya herself struggles to combine her work as a nurse and midwife with being a wife and mother and consequently has experiences of her own in that field. In contrast to Esi, Okopuya has managed to keep her marriage, but only through neglecting herself. Her reaction to Esi’s suggestion that she should have “a proper drink” when they met at the Hotel Twentieth Century is evidence to that. Okopuya claims that alcohol makes her sleepy and makes her want to go to bed too early in the evening, and that a drink would be absolutely out of the question. When Esi ask why sleeping early would be bad Okopuya answers that that would not do at all. She continues to think: “How could she, Okopuya Dakwa, sleep anytime she felt like it? With a fully grown man, a young growing woman and three growing boisterous boys to feed?” (34). Here Okopuya’s demands on herself reveal that she, although resisting oppressive gender roles in some instances, also feels that she is not performing her roles as woman and mother properly if she does not take care of her home and family. She is judging herself with measures she does not really believe in, making herself slide into roles she does not want to play, and is thus upholding male norms of femininity. This brings us to the third and final area of reproduction, namely the symbolical one. 25 Symbolical reproduction As symbolical reproducers women are supposed to reproduce culturally specific behavior and cultural norms of gender, just as Okopuya does in the example above. They are seen as ambassadors or representatives of what the nation stands for with all its attributes inherent in them. Another instance of Okopuya as symbolical reproducer is when Esi tells her about the engagement to Ali. Upon hearing all about it, Okopuya remarked that if she were a white woman, she would have fainted away. But as an African woman, she could only do her thing, which was exclaiming ‘Ei, ei’ several times over, marching up and down the length of the sitting room, and finally taking hold of Esi’s hand, having a proper look at it and asking whether she was sure of what she was saying. (93-94) Here Okopuya expresses that there is a difference between African women and “other” women. She creates a national “us” (or rather a “continental us” since she is talking about African and not Ghanaian women) by contrasting herself and her fellow African sisters against a “them” of “white women” with unidentified national or continental affiliation. In this way Okopuya expresses some sort of national identity with the help of her own gender identity. What also becomes clear in this passage is the mechanism of making “the other” inferior. As I have mentioned earlier “the other” has been classified as feminine, that is as inferior and weak, in relation to the strong superior “us”. I have also mentioned that women in some cases also exert power over other women or people outside the collective. This is exactly what Okopuya does in the passage above. She constructs African women as strong active agents in contrast to the weak white women who cannot handle the pressure of strong feelings. Being the nation incarnate, women are often represented as weak and in need of male protection. Just as single women are seen as an insult to “the glorious manhood” of men, women have to be represented as weak in order for men to feel strong, and this is exactly what Ali does after he first meets Esi. According to Nfah-Abbenyi, Ali’s fear that “the threatening storm might sweep that woman and her car away” indicates that he sees Esi as a woman in need of protection (Aidoo 4). In his eyes both the car and Esi looks frail (Nfah-Abbenyi 284- 85). Ali thus uses Esi’s womanhood and alleged frailness as a tool to create his manhood and masculinity. However, when Oko tries to assess his masculinity the same way he fails because of Esi’s independence towards him. It makes him feel like less of a man. Her independence lies in that she has control of her biological reproduction, that she prioritizes her career and that she travels a lot with work and as a consequence has an unusual freedom of mobility. All of the above leads Oko to ask the question if Esi really is an African woman. In his eyes her independence invalidates all the norms of femininity he is accustomed to. Nevertheless, he is not blind to the fact that there are alternative femininities at work in his society, because he answers his own question with a yes. Not only is Esi an African woman, “but there are plenty of them around these days…these days…these days” (Aidoo 8). The problem for Oko seems to be that he is not willing to let go of the privileges and comfort it brings to hold on to his old set of gender roles in order to embrace new ones. Esi’s alternative assertive femininity also invalidates his role as protector and renders him useless. She does not need him and he is thus made passive, while she is active. Esi recognizes, just as the mothers of Nima, that it is “a man’s world”, but instead of accepting that “[y]ou only [survive] if you knew how to live in it as a woman” Esi chooses to act as if the fact that she is a woman does not matter (107). That choice has severe repercussions for her since the society she lives in has no place for a woman acting as if she were a man. The result is once again a state of confusion and a sense of rootlessness. In the analysis above I have established that some of the female characters accept the roles as biological, cultural and symbolical reproducers of prevailing gender identities and national identities, and play the part without a battle. Others resist some or all of these roles on the grounds that they confine them to a narrow world of passiveness. These women know that they are more than reproducers, they are producers and constructers of gender identities and national identities, albeit that these identities do not necessarily converge with the ones based on male ideas. However, in their strife to evade male control and gain recognition as active agents of the nation their subversion of existing gender roles has brought with it a state of confusion. As they contribute to the society just as much as men, and maybe even more, their demand is to be recognized and rewarded as producers and not only as reproducers. This is a demand yet to be granted, since the male hegemony in society is reluctant to make the adjustments needed for this to happen. Conclusion My aim with this essay has been to point to the intersections between gender identity and national identity in *Changes* and by that theoretically prove what the novel claims, namely that women are producers, not just reproducers, of the identities in question; and as producers and active agents of nation building women should be awarded for their work with the power to define national identities on the same terms as men. With my theoretical background on gender identity and national identity I have laid bare principles that govern society such as power relations between men and women as well as between nations. Such principles are the processes of identification which are the same in the formation of both gender identity and national identity and are based on the binary pair of “the Self” and “the Other”. In the first part of the analysis I have examined how gender is portrayed in the novel. What I have found is that there are multiple gender identities at work simultaneously in a society weighed down with inequalities between women and men. In a society controlled by men, femininities that resist male dominance, such as the ones of Esi and Okopuya, are met with opposition both from men and from other women. Another matter that becomes clear is the problem to redefine gender roles. It becomes apparent that in order to bring about a change of women’s conditions there must be a transformation of the society as a whole. The second section has had its focus on national identity and how this concept is contended by other influences, such as education, ethnicity and also gender. The belief that education and mingling of ethnicities will promote a national identity is proven wrong with the example of the teacher’s training college of Ali and Fusena which was meant to make different ethnicities come together but did not succeed in doing so. I have shown that while education is of good it may in some cases, as the case with Esi, bring with it confusion about national identity. The fact that Ali does not experience the same confusion as Esi drives me to the conclusion that there is a difference between the possibilities that women and men have to define national identity. In the third and last part of the analysis I introduce and explain the intersection of gender identity and national identity both in theory and in the novel. This intersection of the two identities lies in that they constitute each other. Ideas of gender identities help form national identities which in their turn consolidate and reproduce gender identities. This relationship has its grounds in that national identity and the nation has its roots in gender identity and the family. Power relations between men and women that stem from the family are reproduced in the nation and thus constitute national identity, and the gender inequalities in the former are therefore also present in the latter. With the help of Nira Yuval-Davis’ classification of women as biological, cultural and symbolical reproducers of prevailing gender identities and national identities I have analyzed the novel. In that analysis I have established that these traditional roles confine women to be passive reproducers while men remain active producers. Yet, the novel shows that women not only are reproducers but also producers of both gender identities and national identities and accordingly contribute to the creation of the nation and national identity. As such they should be rewarded with the same benefits as men, but due to cemented gender roles invented by a male dominated society they are not allowed to do so. While some of the female characters conform to these traditional roles, others resist them with more or less perseverance. When trying to claim their right to the benefits just mentioned they are forced to break traditional gender roles of femininity, and since there is not room for more than one “legitimate” femininity they are seen as unfeminine or, as Esi and Okopuya state as the case for unmarried women, they become invisible. The problem however does not lie in the actual opposition but in the confusion that comes with it, a confusion that emanates from the fact that there is no room in society for other gender roles than those produced by the male “ego”. My conclusion is thus that the novel shows that in a nation such as Ghana, women and men have very different possibilities to define gender identities and national identities, and women have little or no chances to define themselves as active subjects, both as women and as Ghanaians. I hold that this is due to the fact that women are welcome to contribute to the society on a level of reproduction but barred from the public sphere where norms of gender identities and national identities are formed. Furthermore I maintain that the novel claims that women’s struggle towards autonomy is hampered by the state of confusion that arises when women are prevented from redefining the old roles they have superseded. However, despite this dreary depiction of the lives of African women I discern a ray of hope that their situation can be bettered in the speech that Nana holds to Esi. As an answer to her own rhetorical question if the gender dynamics and political dynamics always have to remain as they are Nana says: Certainly not. It can be changed. It can be better…. But it would take so much. No, not time. There has always been enough time for anything anyone ever really wanted to do. What it would take is a lot of thinking and a great deal of doing. But one wonders whether we are prepared to tire our minds and our bodies that much. Are we human beings even prepared to try? ‘Otherwise, it is very possible for life on this earth to be good for us all. My lady Silk, everything is possible.’ (111) Although this passage contains a speck of doubt whether Nana’s scenario ever will take place it also holds a hope and a possibility that it will, if people are willing to try. Works Cited Primary Source Secondary Sources http://lit.enotes.com/contemporary-literary-criticism/aidoo-ama-ata/introduction
<table> <thead> <tr> <th>Section</th> <th>Title</th> </tr> </thead> <tbody> <tr> <td>Instructions for use</td> <td>Lower Devonian Crinoid Pernerocrinus from the Southern Kitakami Mountains, N.E. Japan</td> </tr> <tr> <td>Author(s)</td> <td>Minoura, Nachio</td> </tr> <tr> <td>Citation</td> <td>北海道大学理学部紀要 = Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy, 22(2): 337-355</td> </tr> <tr> <td>Issue Date</td> <td>1987-08</td> </tr> <tr> <td>Doc URL</td> <td><a href="http://hdl.handle.net/2115/36754">http://hdl.handle.net/2115/36754</a></td> </tr> <tr> <td>Type</td> <td>bulletin (article)</td> </tr> <tr> <td>File Information</td> <td>22_2_p337-355.pdf</td> </tr> </tbody> </table> Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP LOWER DEVONIAN CRINOID PERNEROCRINUS FROM THE SOUTHERN KITAKAMI MOUNTAINS, N.E. JAPAN by Nachio Minoura (with 4 text-figures, 2 tables and 3 plates) Abstract Three species of Crotalocrinitidae crinoids, Pernerocrinus hayasakai (Minato and Minoura), P. perforatus sp. nov. and P. sp. are described. All these species came from the lower part of the Ohno Formation (Lower Devonian) of the southern Kitakami Mountains. The first species was previously described as a tabulate coral, Ohnopora hayasakai gen. et sp. nov., belonging to the family Syringolithidae. Robust construction of the Pernerocrinus is interpreted to be especially well adapted to reef environment and its occurrence is strictly confined, at present, to the Lower Devonian. Introduction One of the crinoids described in this article was collected by the late Prof. M. Minato of Hokkaido Univ. in 1950, at Ohno, type locality of the Lower Devonian Ohno Formation in the southern Kitakami Mountains. At first it was taken to be as a Thecostegites (Minato et al., 1959), but was later described as a new tabulate coral Ohnopora hayasakai, belonging to the family Syringolithidae (Minato and Minoura, 1977). All the specimens available then were fragmental molds with no original calcite skeletons left. Some were interpreted as molds of fragmental colonial corallites and others as tabulae and walls replaced by silica. Two tubes, parallel to the walls and penetrating the tabulae, and tubules connecting these tubes (Minato and Minoura, 1977) are so strikingly unusual in tabulate coral that Hill (1981, F558) expressed strong doubts for including it in the family Syringolithidae. Thus, she stated “systematic position problematical; horizontal canals in tabulae otherwise unknown in the Tabulata”. Meanwhile, several additional specimens were found in 1981 and 1982 at a few localities close to Ohno, and although all this new material also is fragmental, none being complete, preservation of some is such that the original calcite skeletons are partially undissolved with evident echinodermata microstructure. Accordingly, transfer of Ohnopora from Coelentrata to Echinodermata became necessary, and its close resemblance to Pernerocrinus was pointed out (Minato et al., 1982). Detailed examination and comparison of all the specimens reveals that they are generically identical to peculiar Crotalocrinitidae crinoid Pernerocrinus Bouška (1946), known from the lower Devonian of Bohemia (Bouška, 1946) and of Australia (Bates, 1972). Detailed comparison with Pernerocrinus and other allied genera highlighted such morphological characteristics as more regularly arranged alternating brachia and Contribution from the Department of Geology and Mineralogy, Faculty of Science, Hokkaido University, No. 1929. heteromorphic columns in the Japanese specimens. Consequently, *Ohnopora* is now believed to be a junior synonym of *Perneroocrinus*. One specimen, included in the new material, is nearly identical to *P. hayasakai* in general morphology. Nevertheless, rather large interarticular canals, sporadically and transversely penetrating the entire depth of preserved brachial disc of this specimen, is significant to establish a new species, *Perneroocrinus perforatus*. This paper deals with the description of these two peculiar crinoid species and an undeterminable form, *P. sp.* **Systematic description** Class Crinoidea Miller, 1821 Subclass Inadunata Wachsmuth and Springer, 1885 Order Cladida Moore and Laudon, 1943 Suborder Cyathocrinina Bather, 1899 Superfamily Gasterocomacea Roemer, 1854 Family Crotalocrinidae Bassler, 1938 Genus *Perneroocrinus* Bouška, 1946 *Type species* (by original designation): *Perneroocrinus paradoxus* Bouška 1946 *Diagnosis*: “Large, thick walled crinoid composed of massive element. Crown heavy, low and broad. The plates of cup and column are extremely elongate in transverse direction. Arms constructed similarly as in crotalocrinitid but without meshes. The brachials are in firm contact laterally both within the rays and between adjacent rays. The tegmen consists of a large number of small, thick plates which are unequal in shape and size. Column short, broad, joined inconspicuously to the cup. Root heavy with long branching appendages” (Bouška, 1950) Some of the supplementary statements given by Bates (1972) are as follows: tube-like column with very wide lumen; arms fused into a solid subhorizontal disc pierced by large axial canals and bearing on its upper surface adoral grooves; no anal plate. Subhorizontal and thick discoid crown is quite characteristic for this peculiar crinoid. Even fragmental molds of disc, frequently found in the Ohno Formation, are at least generically identifiable by “appearance of *Favosites* structure” as mentioned by Bouška (1950). *Discussion*: The taxonomic relationships between *Perneroocrinus* and such other Crotalocrinidae genera as *Crotalocrinites, Enalloocrinus* and *Syndetocrinus* has been sufficiently discussed by Bouška (1950) and by Bates (1972). But whereas the present writer fully agrees with their suggestions, it is to be noted that interarticular canals found in *P. perforatus* superficially recall the net-work structure of the arms of *Crotalocrinites*, although the function or the morphological details of these canals are still unknown. *Included species:* *Perneroocrinus paradoxus* Bouška, 1946, Koneprusy, Central Bohemia; Lower Devonian. *Paraperneroocrinus sibiricus* Yakovlev, 1949, Northern Ural, USSR; Coblenzian. *Perneroocrinus discus* Bates, 1972, Lilydale Ls., Victoria, Australia; Siegenian-Emsian. **Perneroocrinus hayasakai** (Minato and Minoura), 1977, Ohno Formation; Lower Devonian **Perneroocrinus perforatus** Minoura, 1987, Ohno Formation; Lower Devonian **Perneroocrinus hayasakai** (Minato and Minoura) (Pl. 1, figs. 1-3; Pl. 3, fig. 1; Text-figs. 1, a-c; 3, a; 4, a-d) 1959 *Thecosregire* sp., Minato et al., p. 75 (listed only) 1977 *Ohnopora* hayasakai Minato and Minoura, p.560, pl. 3, figs. 1,2. 1979 *Ohnopora* hayasakai, Minato et al., p.62, pl. 8, figs. 1-4, pl. 9. 1982 *Ohnopora* sp., Minato et al. p.773, pl. 1, fig. 1; non figs. 2-4. **Material:** Partial inner mold (UHR 30190-3 = Holotype of *O. hayasakai*); Outer mold of partial disc (UHR 30189 = Paratype of *O. hayasakai*); Partial disc (UHR 30669); Outer mold of partial disc and column (UHR 30668); Outer mold of partial disc (UHR 30672). **Locality and horizon:** No less than 20 fragmental specimens are known from Oh1 and Oh2 Members designated by S. Haga (1978, M.S.: in Minato et al., 1979) of the Ohno Formation. Specimens herein described and figured are collected from the following localities, all in Ohfunato City, Iwate Pref.; UHR 30189 and UHR 30190: Ohno, Hikoroichi, coll. by M. Minato; UHR 30668 and UHR 30672: Namerishi*, Hikoroichi, coll. by S. Haga; UHR 30669: Eastern Ridge at Ohfunezawa, Okusakamotozawa, Hikoroichi, coll. by H. Yokoyama. **Description:** Column is estimated to be circular and its outside diameter attains 45 mm, slightly tapers distally to about 35 m, large lumen occupies more than 80 percent of the outside diameter of the column (Text-fig. 4, d). Internal surface of the lumen appears to be heteromorphic, at least partially, formed of lower (0.8-1.0 mm), and higher (1.8-2.0 mm) columnals. These two types of columnals, longitudinally alternate with each other, and have vertical seams, which in the former are 1 mm and in the latter 2-4 mm apart (pl. 2, figs. 1a,b; Text-fig. 3, a). Details of the other part of the column and presence of root are unknown due to poor or no preservation. Plate arrangement of the crown except that of brachials is not observable. Uniserial brachia, bifurcate isomorphously at repeated intervals of every 5-10 brachials, are in firm contact with each other, laterally fused into a solid subhorizontal disc (Text-fig. 1, a-c). Brachials are extremely deep, more than 10 times deeper than the height, pierced by axial canals at about two-third depth from the adoral surface where deep U-shaped adoral grooves are present. Brachial articulation is syzygial. Between successive brachials exist a central and two lateral canals vertically connecting the adoral groove and the axial canal (pl. 1, figs. 2,3b). Laterally fused arms are alternately arranged, giving most brachials flattened hexagonal shape both in dorsal and ventral outlines (Text-fig. 1). Width of the brachial is 1.5-2.1 mm, height is 1.2-1.7 mm. **Comparison:** This species is slightly larger than *P. discus* and having more regularly alternating brachia, if not entirely so. Heteromorphic column of the present form, though observed only in a rather ill preserved specimen, is entirely unknown in other species. *P. sibiricus* and *P. perforatus* are of nearly the same size as this species. * Practically same locality to Ohno. Text-fig. 1 Brachial plate arrangement of *Pternocrinus hayasakai* (Minato and Minoura) (scale-bar is 10 mm). a: Ventral surface drawn from the photo shown as plate 1, fig. 1a. b: Dorsal surface from plate 1, fig. 1b. c: Ventral side from Plate 1, fig. 3a. However, lateral canals are absent in the former species and interarticular canals are present in the latter form. *P. paradoxus* is extremely large in size in comparison with all other species, and has characteristic rolled-up free arms. **Perneroocrinus perforatus** sp. nov. (Pl. 2, figs. 1-3; Text-figs. 2, a-b; 3, b-c; 4, e) 1982 *Ohnopora* sp., Minato et al. p.773, pl. 1, figs 2-4; non fig. 1. **Derivation of the specific name:** Interarticular canals appear as if they are perforating the disc. **Material:** The material (Holotype, UHR 30671), consists of slightly deformed partial column and disc, was originally found in a hand specimen (pl. 2, figs. 2a,b). **Locality and horizon:** Only one specimen here described is known from the lower part of the Ohno Formation at Ohfunezawa, Okusakamotozawa, Hikoroichi, Ohfunato City, Iwate Pref., coll. by H. Yokoyama. **Specific diagnosis:** *Perneroocrinus* with interarticular canals. **Description:** Although its preservation is the best of all the Japanese material of *Perneroocrinus*, both adoral and aboral surfaces are lacking probably due to the abrasion before being entrapped in the sediment. Further, no more than half a millimeter of the specimen was ground before removing surficial matrix. Column is also slightly ground down, thus no more than a millimeter is lost except lower several millimeters of the column, where a few millimeters are ground to attempt observing the columnal outer surface (pl. 2, figs. 2a,b). Although less than half a disc is preserved, its diameter is estimated to be no less than 65 mm and reconstructed to be 100–110 mm. Maximum depth of the preserved brachial is 14 mm. Width attains 1.5 and 1.8 mm on preserved dorsal and ventral sides, respectively. Height is no more than 1.5 mm. Arm branching is isomorphous and its alternate arrangement (Text-fig. 2, a,b) is not so significant as that of *P. hayasakai*. And brachial plate arrangement at proximal dorsal side seems rather irregular, therefore, brachials at this portion may be vertically twisted. Plate arrangement at calyx is unknown. No adoral groove is preserved. Axial canals, oval in ventrodorsal cross section and 0.5–0.6 × 0.8 mm in size penetrate the brachials. Between each brachial, a central canal, less than half a millimeter diameter, and two lateral canals, smaller than the former are present, though not always they are visible in lateral view (pl. 2, fig. 1b). Two to five rather thick interarticular canals, 0.5–1.0 mm in diameter, exist between each brachia (pl. 2, figs. 1a,b; Text-fig. 2, a,b). None is seen in proximal 10–12 brachials, but they appear at preserved 13–15th brachial, and further distally in intervals of every 3–5 brachials. They penetrate entire depth of preserved brachial disc, e.g. below the level of axial canals aborally. Although detail of these interarticular canals are unknown, they are not gonioporoid exospires. Since their distribution is too irregular and sporadic, and they seem much larger than ordinary exospires. Although morphologically they are quite different with each other, superficially these canals Text-fig. 2 Brachial plate arrangement of *Perneroocrinus perforatus* sp. nov. (scale-bar is 10 mm). a: ventral side drawn from photo shown as plate 2, fig. 1a. b: dorsal side from plate 2, fig. 1b. Axial canals are stippled and interarticular canals are diagonally ruled. rather recall net-work structure of *Crotalocrinites*, whose arms are believed to be more or less flexible. Column is estimated to be circular and slightly tapers distally (Text-fig. 4, e). External diameter at proximal portion and length preserved are about 40 and 50 mm, respectively. Diameter of the lumen at proximal portion is 23 mm and slightly tapers distally to 20 mm. Height of proximal columnals is 2.5 mm, gradually decreases to 1.1 mm at distal edge (pl.2, figs. 3a,b, Text-fig. 3, c). Thickness of the columnal wall is about 4–5 mm but its external surface is not exactly known, since outer surface of the column is full of numerous facets for the reception of roots. These are round, hexagonal or octagonal in shape, 3–6 mm in diameter, and centers are pierced by central canals, of oval or kidney-bean shape (pl. 2, figs. 2a,b, Text-fig. 3, b). These central canals internally appear, on the facets of every or every other columnal, as if aligned along longitudinal rows 6–8 mm apart (Text-fig. 3, c). At least several proximal col- Text-fig. 3 Sketch showing the plate arrangement of column. (scale-bar is ca. 10 mm) a: internal surface of the lumen of *Pernerosocrinus hayasakai* (Minato and Minoura) drawn from photo shown as plate 3, fig. 1a. b: Weathered external surface of column of *Pernerosocrinus perforatus* sp. nov. from plate 2, fig. 3b. c: internal surface of the lumen of *Pernerosocrinus perforatus* sp. nov. from plate 2, figs 3a, b. umnals seem to have longitudinal or sinuous seams in random interval. Thus internally ground surface of the lumen appears as if layers of bricks with many vertically aligned black spots between the layers (Text-fig. 3, b,c). No distinct root is preserved, but numerous roots are apparently suggested by numerous facets, and they probably attach even at proximal column. **Comparison:** Size and shape of this species closely resemble those of *P. hayasakai*. Interarticulcral canals sporadically develop at relatively distal part of the brachial disc constituting most significant character of the present species, entirely unknown in any other species. **Perneroocrinus sp.** (Pl. 3, figs. 2a-c; Text-fig. 4f) **Material:** Partial outer mold of a disc with tegmen and branching roots (UHR 30670) **Locality and horizon:** Oh1 Member of the Ohno Formation at Nameriishi, Ohmorizawa, Hikoroichi, Ohfunato City, Iwate Pref. coll. by S. Haga. **Description:** Brachial disc preserved is no more than one fourth of an individual, and its total height is 92 mm. Accordingly, it is reconstructed to be 240 mm in original diameter. Brachials appear, though very few can be observed, as flattened hexagonal in outline, by which alternate arrangement of brachia is suggested (pl. 3, fig. 2b). Depth of brachial reaches at least 20 mm, height and width are 1.8 mm and 2.2–2.4 mm, respectively. This extremely deep brachial is pierced by an axial canal, at 2/3 to 3/4 depth from the adoral surface, where deep U-shaped adoral groove presents. Width of the axial canal, judged from its mold, is 1.1–1.5 mm in diameter, and that of the groove is 1/2 to 1/3 of that of the brachial. The former is wider and the latter is slightly narrower than those of the other species. Extremely thin, less than 0.4 mm wide and 0.8–1.0 mm high, slit-like structures vertical to the both sides of the groove probably are mold of the facets for covering plates (pl. 3, fig. 2c). Central canals, connecting the groove and the axial canal, are present between successive brachials. Although several molds of wall-like structures are apparent along the central canals, and they are suggestive of lateral canals, no obvious one is recognizable. Isotomous bifurcation of brachia occurs less frequently than in the other species. It means that interval of the bifurcation seems longer in this species than in the other species. Several tegminal plates barely visible are small, 1.5–1.8 mm in diameter, irregular, and appear pentagonal, hexagonal, or octagonal in shape (pl. 3, fig. 2a). Beneath the proximal tegmen opening of adoral grooves and axial canals are seen. Then, thickness of the tegmen is estimated to be 5–6 mm. The lateral extent of the tegmen, which is estimated to be slightly domed centrally, is not exactly known. Nevertheless it may reach more than half the preserved disc (pl. 3, fig. 2a). Three fragmental roots, of which two are apparently branching, are preserved directly on the dorsal side of the disc, circular, in cross section, 7–8 mm wide and at maximum 25 mm long, slightly tapers distally (pl. 3, fig. 2b). These roots are composed of ossicles, about 2 mm high, and are pierced by 2–2.5 mm wide axial canals. No column is preserved. Discussion All the material available in this study is not only more or less deformed and fragmental, but is also mostly poorly preserved outer or silicified inner mold. At best half a disc and partial column of an individual are obtained. Although no less than 20 fragmental specimens, identifiable as Perneroocrinus by its characteristic shape of the mold are known from various localities, only a few are preserved well enough to be determined specifically with some reliability. Reconstructed vertical profile, with some amount of interpretation and extrapolation (Text-fig. 4), would reveal that both P.hayasakai and P. perforatus are nearly identical in outer shape and size. Disc diameter in these two species is estimated to be 130–110 mm and 122 mm, respectively. And column diameter of P. hayasakai is 45 mm (UHR 30668), while that of P. perforatus is 40 mm (UHR 30671). Measurable thickness of columnal wall is 4 mm in the former species and 5 mm in the latter species. Variation in outer shape is rather apparent in the former species as steep (UHR 30668) and gentle (UHR 30189) curvature of the proximal ventral profile. Size and shape variations found in P. hayasakai and P. perforatus are much less significant than those in P. discus described by Bates (1972). Column diameter of P. discus ranges from 18 to 40 mm. Thickness of the columnal wall ranges from 1.7 to 3.8 mm. Disc is basically subhorizontal on a vertical column, but an umbrella-like convex one, irregularly sloping away from the central tegmen, and a shallow bowl-shaped concave one, are mentioned for the Australian form (Bates, 1972, p. 333). Size of skeleton in various species of Perneroocrinus is indeed quite variable. Actually column diameter in various forms of the genus ranges from 18 to 100 mm or more, of which the largest one has been suggested as one of the widest fossil crinoidal column (Ubaghs 1978, T63). Nevertheless, no detailed size comparison has been made yet for the genus. Based on descriptions and measurements on illustrations, various sizes of most specimens described and figured are tabulated (Table 1) to delineate different specific characters of Perneroocrinus. Included are those of allied genus Paraperneroocrinus Yakovlev 1949, which is a junior synonym of Perneroocrinus, as mentioned elsewhere. Since plate size is so variable even in a specimen, as axillary is sometimes nearly two times wider than that of brachial, it is, calculated in such a manner that several plates are measured together at a time. This procedure is repeated on as many portions of a specimen as possible and then averaged. Even disc diameter has not been described, it is easily measurable on the illustrations if distal edge of the disc is preserved. Unfortunately, all Perneroocrinus described and illustrated are fragmental and none is complete. Accordingly, it is not directly measurable on the illustrations. Disc diameters in Table 1, therefore, are estimated after such a rather lengthy discussion as follows: *P. paradoxus* is reconstructed to have rolled-up free arms all around its distal edge (Bouška, 1950, Text-fig. 4), though no specimen with free arms directly attached to the disc is known but based on separately found fragmental rolled arms. This fact may suggest that the fragmentation is most susceptible at or close to the distal edge of the disc, if flexible arms are present. On the Australian specimens no such free arms are suggested, because distal edge of some specimens is rounded and no fragment of rolled-up portion of arms is found (Bates 1972, p.333). Although distal parts of all the Japanese specimens are missing due to fragmentation and presence or absence of free arm is unknown, no fragment suggesting rolled portion of the arms is found. In an arm of an Australian specimen which its distal edge seems rounded (pl. 58, fig. 9), 22 brachials, at maximum, are counted. Bifurcation in this arm is four. In the Japanese specimens, 24 brachials with 4 bifurcations at maximum are preserved in an arm of UHR 30671 (Text-fig. 2, a). Table I Size of specimens of *Penerocrinus* in mm, except width of adoral groove and axial canal which are indicated by ratio to width of brachial. Depth of adoral groove also is ratio to width of adoral groove. Disc diameters in parentheses are calculated values by the following equations, as discussed in the text: D = 28 x h x 2 + C.W. (Japanese specimens) D = 25 x h x 2 + C.W. (Australian specimens) where h is height of a brachial; C.W. is column diameter. v. and d. at top of the column denote measurements on ventral and dorsal surfaces, respectively. * Value originally described but differs from the measurement on illustrations. <table> <thead> <tr> <th>Specimens</th> <th>Brachials</th> <th>Column (als)</th> <th>Lumen</th> <th>Disc</th> <th>Adoral groove</th> <th>Canal</th> </tr> </thead> <tbody> <tr> <td></td> <td>height n</td> <td>width n</td> <td>depth</td> <td>width</td> <td>height</td> <td>thickness</td> </tr> <tr> <td>UHR30668</td> <td>v. 1.51 25</td> <td>2.06 9</td> <td>15.4</td> <td>45-35</td> <td>2, 1</td> <td>4-3</td> </tr> <tr> <td>UHR30669</td> <td>v. 1.67 95</td> <td>1.75 70</td> <td>26</td> <td>15+</td> <td>80+</td> <td>2/3</td> </tr> <tr> <td>d. 1.66 23</td> <td>1.43 32</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>UHR30189</td> <td>v. 1.41 35</td> <td>2.04 31</td> <td>13</td> <td>30</td> <td>207</td> <td>71+(109)</td> </tr> <tr> <td>d. 1.18 25</td> <td>2.06 29</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>UHR30672</td> <td>v. 1.36 67</td> <td>1.49 65</td> <td>14+</td> <td>40-25</td> <td>2.5-1.1</td> <td>5-4</td> </tr> <tr> <td>d. 1.47 45</td> <td>1.77 38</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>pl.3, fig.1</td> <td>v. 1.84 12</td> <td>2.17 12</td> <td>20</td> <td>190+</td> <td>1/3</td> <td>1.5</td> </tr> <tr> <td>d. 1.84 12</td> <td>2.17 37</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>pl.3, fig.2</td> <td>v. 1.34 5</td> <td>5.29 10</td> <td>36</td> <td>100</td> <td>1.83</td> <td>15</td> </tr> <tr> <td>d. 2.84 6</td> <td>6.32</td> <td>10</td> <td>31</td> <td>95+</td> <td>3/4</td> <td>1/3</td> </tr> <tr> <td>pl.4, fig.1</td> <td>v. 2.30 34</td> <td>2.65 21</td> <td>15.6</td> <td>100</td> <td></td> <td></td> </tr> <tr> <td>d. 2.30 34</td> <td>2.65 15</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>pl.4, fig.4</td> <td>d. 2.30 34</td> <td>2.65 21</td> <td>15.6</td> <td>100</td> <td></td> <td></td> </tr> <tr> <td>pl.4, fig.4</td> <td>d. 2.30 34</td> <td>2.65 21</td> <td>15.6</td> <td>100</td> <td></td> <td></td> </tr> <tr> <td>pl.4, fig.4</td> <td>d. 2.30 34</td> <td>2.65 21</td> <td>15.6</td> <td>100</td> <td></td> <td></td> </tr> <tr> <td>P 26707</td> <td>d. 1.26 33</td> <td>1.24 36</td> <td>9.6</td> <td>27</td> <td>3</td> <td>21</td> </tr> <tr> <td>P 26699</td> <td>v. 1.69 84</td> <td>2.41 37</td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>P 26696</td> <td>v. 1.71 15</td> <td>1.40 3</td> <td>7.9-4.4</td> <td>1</td> <td>44+</td> <td>1/2</td> </tr> <tr> <td>d. 1.71 15</td> <td>1.40 3</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>P 26695</td> <td>v. 1.82 32</td> <td>2.22 20</td> <td>8.5-5</td> <td>20</td> <td>42+(67)</td> <td>1/3</td> </tr> <tr> <td>d. 1.82 32</td> <td>2.22 20</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>P 26691</td> <td>v. 0.94 15</td> <td>1.96 35</td> <td>1.96 35</td> <td>29</td> <td>3.5</td> <td>22</td> </tr> <tr> <td>d. 0.98 12</td> <td>1.96 35</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </tbody> </table> Rigid construction of completely fused brachial disc of this genus *Pernerocrinus* may allow an assumption that abrasion by current action is more or less limited and possibly occur concentrically. Actually, fragmental specimens of not only some of the Australian but also the Japanese forms retain somehow circular lateral outline at preserved distal edges, which suggests that the above assumption is not too absurd, if not very precise. Then the above maximum number of brachial plates preserved in both the Australian as well as the Japanese specimens can be considered to denote not very far from the distal edge of the disc. This means less than 25 brachials, with some allowance, may limit the distal edge of arms of the Australian specimens. In the same way, less than 28 plates are considered to characterize the Japanese specimens. Once distal edge of the disc is defined as above, disc diameter can be calculated simply, by multiplying the average height of brachial plate, number of plates and two, added to the column diameter. Although this estimation is based on quite an arbitral assumption applied to the Australian and the Japanese specimens only, profiles of the Japanese material thus obtained show similarity to both Bohemian and Australian species. This would suggest certain amount of reliability for the procedure of the reconstruction. As above measured and estimated, size of the skeleton is extremely variable as apparent in Table 1. Also plate size is quite variable even within a species. Nevertheless, two groups can be easily discriminated by size of disc and column. One is larger, having column and/or disc diameters more than 90 mm and 200 mm, respectively. The other is smaller less than 45 mm and 130 mm. The larger group includes such species as *P. paradoxus* and *P.* spp. of Bates and of this study. The smaller group includes *P. discus*, *P. hayasakai* and *P. perforatus*. Although size difference seems to be gradual and no critical limit is apparent, *P. hayasakai* and *P. perforatus* are considered to be slightly larger than *P. discus*, even thecal plates of these three species seem in a same size range as a whole. Since, column and disc of *P. hayasakai* and *P. perforatus* can be in a same size range, but are slightly larger than those of *P. discus*. Besides, brachials are much deeper in the former two species with 13–15 mm, than those of the latter which measures 7–10 mm. Accordingly, although not so apparent in appearance, *P. discus* is judged to be smaller than the former two species. *Parapernerocrinus sibiricus* Yakovlev 1949 is apparently in the same size-range of the smaller species, in column diameter, wall thickness and plate size, though some wide brachials are figured (Yakovlev, 1949, pl. 1, figs. 7,8; pl. 2, fig. 1), and exact disc diameter is unknown. On this point, together with very slight morphological distinction, the author quite agrees with Bates (1972, p.333) to include this species in the genus *Pernerocrinus*. Although the larger species can be grouped as having extremely large disc, which ranges from 200 to 300 mm or more, thecal plates of these species are extremely variable in size. Those of *P. paradoxus* are quite large, nearly twice as large as those of the smaller species in every dimension. Those of *P.* spp. of Bates and of this study, are approximately same size-range to those of the other smaller species (Table 1). Significance of this relatively small plates of these two species is not well understood. but will be later discussed briefly. As above mentioned, even great size variability is characteristic in the genus *Pernerocrinus*, all species can be arranged in such an order from small to large, as *P. discus*, *P. hayasakai*, *P. perforatus*, *P. sibiricus*, *P. sp.* of this study, *P. sp.* of Bates and *P. paradoxus*. Distinction between the smallest *P. discus* and the largest *P. paradoxus* by size is a matter of evidence. Size difference of the smaller four species is so gradual and sometimes overlaps that no significant limit is appreciable. Nevertheless, presence or absence of certain skeletal elements is so significant that specific distinction among these four species is readily made. Lateral canals develop in *P. discus*, *P. hayasakai* and *P. perforatus*. Interticular canals are restricted in *P. perforatus*. Heteromorphic column is known only in *P. hayasakai*. Further differences are as follows: Adjacent arms of *P. hayasakai* and *P. sibiricus* are mostly alternate with each other thus brachials are mostly hexagonal shape both in ventral and dorsal outlines. Cup plates of *P. sibiricus* and columnar plates of *P. perforatus* are, at least partially, sinusuous in outline. Adoral grooves of *P. sibiricus* is described as isosceles triangle shape in cross-section while those of other species are U-shaped. Key to discriminate the species of the genus *Pernerocrinus* is briefly tabulated in Table 2. Among the larger three species, *P. paradoxus*, *P. sp.* of Bates and of this study, the first species is quite distinct in having rolled-up free arms, extremely large skeletal plates consisting the disc, and axial canals penetrate at relatively close to the dorsal surface. Distinction between the latter two species is more or less vague in many aspects. Disc diameter and size of the skeletal plates are nearly compatible between these two species (Table 1). Axial canals are relatively larger than those of the other species. Root system of the Australian specimen is directly attached to cup and disc, without intervening stem, while fragmental roots are preserved directly on the dorsal side of the disc, even column is unknown, in the Japanese specimen. Furthermore, lateral canals are apparently not developed in the Australian form, while those of the Japanese form <table> <thead> <tr> <th>species</th> <th>size</th> <th>arm alternation</th> <th>lateral canal</th> <th>interarticular canal</th> <th>movable arm</th> <th>root</th> </tr> </thead> <tbody> <tr> <td><em>P. paradoxus</em></td> <td>large</td> <td>slightly</td> <td>no</td> <td>no</td> <td>present</td> <td>many</td> </tr> <tr> <td><em>P. discus</em></td> <td>small</td> <td>partly</td> <td>present</td> <td>no</td> <td>no</td> <td>many</td> </tr> <tr> <td><em>P. sibiricus</em></td> <td>medium</td> <td>mostly</td> <td>no</td> <td>no</td> <td>unknown</td> <td>unknown</td> </tr> <tr> <td><em>P. hayasakai</em></td> <td>medium</td> <td>mostly</td> <td>present</td> <td>no</td> <td>unknown</td> <td>unknown</td> </tr> <tr> <td><em>P. perforatus</em></td> <td>medium</td> <td>mostly</td> <td>present</td> <td>present</td> <td>unknown</td> <td>many</td> </tr> <tr> <td><em>P. sp.</em>, Bates</td> <td>large</td> <td>partly</td> <td>no</td> <td>no</td> <td>unknown</td> <td>many</td> </tr> <tr> <td><em>P. sp.</em>, Minoura</td> <td>large</td> <td>mostly</td> <td>unknown</td> <td>no</td> <td>unknown</td> <td>many?</td> </tr> </tbody> </table> are unknown. Although these similarities are suggestive that these two specimens are specifically identical, no confirmation is presently possible. Since both materials are fragmental and detailed comparison is impossible. More material is needed to solve the above problem. **Environmental and geologic implication** Reefal habitat of *Pernerocrinus* is well established both on the Bohemian and the Australian species. Extremely wide stem with complex root system and compactness of the brachial disc of the genus are interpreted for this genus to be highly adapted to reef environment (Bouška, 1949, p.21). Some Australian specimens which are fragmental and embedded in matrix further provide evidences of rolling and abrasion by turbulent current in the reef (Bates, 1872, p.329). In this manner, both the Bohemian and the Japanese specimens also are apparently fragmental and embedded in matrix. Actually, all the Japanese specimens are fragmental and found in hand specimens in which numerous fragmental crinoids and corals are scattered, though very few of them are identifiable. It is quite reasonable to consider, therefore, that the Japanese species also are reef dweller and rolled and abraded before incorporated in sediments. Although no reefal or biohermal structure has been precisely investigated in the Ohno Formation, of which pyroclastic sediments prevailed, lenticular and patched limestones commonly develop in this formation and have been believed as representing small reefs or reef debris. In this way, although not abundant, common occurrence of *Pernerocrinus* from various localities of the Ohno Formation is quite a definite evidence of reef environment. Although *P. paradoxus* and *P. discus* are reported to be from Lower to Middle Devonian by Bates (1972, p.326), the horizon of the former species is described as "Lower Devonian, Barrande’s étage —F-f2—" (Bouška, 1950, p.11) which is correlative to Siegenian. For *P. discus* is described, "the material comes from the lower Devonian Lilydale Limestone, probably upper Siegenian or lower Emsian in age" (Bates, 1972, p.326). Also, the horizon of *P. sibiricus* is "Coblenzian" (Yakovlev, 1949, p.19). Accordingly it is evident that the genus *Pernerocrinus* is restricted to the Lower Devonian. This geologic range of the genus is very well in accordance with the Ohno Formation from which the Japanese specimens are found. Conformably overlying the Silurian Kawauchi Formation, the Ohno Formation is --- **Explanation of Plate 1** scale-bars are 10 mm, a: axial canal, ad: adoral groove, c: central canal, l: lateral canal. Figs. 1-3 *Pernerocrinus hayasakai* (Minato and Minoura) Fig. 1a: Outer mold of partial disc showing ventral surface. Paratype UHR 30189. Fig. 1b: Same as above specimen showing dorsal surface. Fig. 2: Silicified internal mold of partial disc viewed from dorsal side. Holotype UHR 30190-3. Fig. 3a: Partial brachial disc viewed from ventral side. Central canals are not always distinct. UHR 30669. Fig. 3b: Same as above specimen viewed from the distal side. mainly composed of tuffs, and is subdivided into three members, Oh1, Oh2, and Oh3, in ascending order (Haga, 1978 M.S.: in Minato et al., 1979). Although occurrence of megafossils is rather scarce, and none has been described, the following corals are known from the lower two members, Oh1 and Oh2, of the Ohno Formation: This fauna is closely related to “Coblenzian” corals of Europe and Australia and, as a whole, denotes the Lower Devonian. Although the uppermost Oh3 member is barren of megafossils the entire Ohno Formation is interpreted to be deposits ranging from Gedinnian to Emsian, since in addition to the above Lower Devonian fauna, Oh3 member is conformably overlain by Nakazato Formation which yields “Eifelian” to Givetian fauna (Kato and Minato, 1979; Kato et al. 1980). **Acknowledgments** This article is dedicated to the Late Professor Masao Minato of Hokkaido University, who brought the writer’s attention to this peculiar fossil when he jointly worked with him, as a junior author, to describe this material as *Ohnopora hayasakai* in 1977. The writer is extremely grateful to Prof. M. Kato of Hokkaido Univ., without whose kind suggestions, encouragements and criticisms, this article would not have been completed. Prof. R.K. Goel of the University of Roorkee, India, critically read the manuscript and is sincerely acknowledged. The treated material was collected through a long period of more than 20 years by various geologists. Among them Messrs. S. Haga and H. Yokoyama are especially acknowledged who willingly placed their specimens for this study. **References** **Explanation of Plate 2** scale-bars are 10 mm, a: axial canal, c: central canal, i: interarticular canal, l: lateral canal. **Figs 1-3 Pernicerinus perforatus** sp. nov. Holotype UHR 30671 Fig. 1a: Partial disc viewed from ventral side. Central and interarticular canals are distinct, while lateral canals are not visible. Fig. 1b: Same as above specimen viewed from dorsal side. Axial and interarticular canals are tangentially cut, while lateral canals are only sporadically visible. Fig. 2a: Partial disc and column showing specimen before cut into two pieces. Fig. 2b: Opposite side of 2a showing numerous facets for roots. Fig. 3a: Partial column obliquely viewed showing internal surface of the lumen and weathered external surface. Oval black dots are axial canals of roots. Fig. 3b: Distal edge of the internal surface of the lumen showing much lower columnals than the proximal ones. (Manuscript received on April 10, 1987; and accepted on June 11, 1987). --- **Explanation of Plate 3** scale-bars are 10 mm, r: root, s: slit-like structure. **Fig. 1:** *Penerocrinus hayasakai* (Minato and Minoura) UHR 30668. Fig 1a: Internal surface of outer mold of partial column which apparently is heteromorphic. Fig 1b: Artificial cast of the above mold showing nearly same portion and proximal disc. **Fig. 2:** *Penerocrinus* sp. UHR 30670. Fig 2a: Artificial cast after outer mold of partial disc showing ventral side. Fig 2b: As above showing dorsal side. Fragmental roots are faintly visible. Fig 2c: Oblique view of the outer mold showing mold of adoral grooves and slit-like structure.
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“What happens to country” in *Blood Meridian* *Jay Ellis* *University of Colorado* “You wouldn't think that a man would run plumb out of country out here, would ye?” —Toadvine, *Blood Meridian* (285) “I don’t know what happens to country.” —John Grady Cole, *All the Pretty Horses* (299) Twenty years after its appearance, Cormac McCarthy’s *Blood Meridian* inscribes an enduring delineation in his work of now nine novels. The fifth book’s title, and its dense Epilogue contributing to the rich ambiguities of “meridian,” now resonate against a new novel, *No Country for Old Men*. McCarthy’s latest book begins as a West Texas noir, boiling with enough violence to remind the reader of milder passages from *Blood Meridian*. But ultimately, the new book simmers down into the bitterness of an old man’s jeremiad: the good days of riding and justice are gone, and violence seems a thing of youth. This is ironic, though, as most of *Blood Meridian* describes a space devoid of law and morality, and it tests the reader, and its protagonist, with the severity of its violence. Early on, the narrator divulges the book’s central problem: “not again in all the world’s turning will there be terrains so wild and barbarous to try whether the stuff of creation may be shaped to man’s will or whether his own heart is not another kind of clay” (4-5). Toward the novel’s end, one answer to this problem is given by judge Holden: “If war is not holy man is nothing but antic clay” (307). Holden’s position—indeed, the preponderance of the novel’s structure and force—demands a space for unbridled war, for violence unconstrained by pity. One definition of the book’s “meridian,” then, might be this: the line in history before which the problem of the human heart’s will was tried in the fire of pure war. Beyond that line, history takes over: the possibilities of the heart are indeed become molded like clay, fired in killing, and now cracked in guilt. In the Epilogue of *Blood Meridian*, McCarthy ultimately renders space into place through enigmatic yet historical details, describ- ing the coterminous lines of three salient events in the West: the nearly complete genocide of a people, the nearly complete extermination of an animal, and the realization (in carefully mechanical enlightenment terms) of an abstraction bringing space into the order of place. The nostalgic last image of *No Country for Old Men*, of a father carrying fire in a horn and riding into the darkness of the past, then, seems less Jungian and more recent. Heroic as this image may seem within that book, the terrain of this dream image remains startlingly safe compared to any of the country in *Blood Meridian*. Located firmly this side of the blood meridian, then, this image of patriarchal authority more readily recalls the country just lost in the popular *All the Pretty Horses*, whose action begins fifty years after the time of *Blood Meridian*’s Epilogue. The ideal Western myth has always been hard to pin down inside of a range of some ten years of historical reality that barely occurred. A return to *Blood Meridian*’s Epilogue will remind us that the golden time longed for at the end of McCarthy’s latest book—if it ever existed—was purchased with the blood of thousands of people and animals, and at the price of inscribing across the vast spaces of the American West the rectilinear constraints that only civilized humans could dream up, and that only barbarous humans could enforce. This does not mean, of course, that McCarthy’s best work can be reduced to the level of suasion. Along with an absence of families, nothing is so persistent in all McCarthy’s books as the idea that violence is timeless. But the wistfulness and regret that color McCarthy’s later novels, as well as the temptation to nostalgia—even as his best writing always indicates the inefficacy of that nostalgia—only heighten our sense, since *Blood Meridian*, that something has happened to country, and that whatever has happened is more complex than the mere loss of some better time. Widely read as an antinomian revel, *Blood Meridian* rather eventually describes a shift in time; although most of its story details the lawless violence of a roaming gang, the book includes the story of their inevitable constraint and defeat (with the notable exception of the judge, dancing forever). Beyond the line indicated by the book’s title, something indeed happens to country: antinomian space becomes historical place. And with that shift comes the burden of memory, loss, and even the sentimentality that overtakes McCarthy’s latest novel. That sentimentality usually remains at the convincing level of buried sentiment, and it is easiest to see in two relations: one between the son and the father (and this has been usually so deeply buried, yet so acrimonious, as to seem like anything but sentiment); the other between McCarthy’s heroes and their physical settings. Because the second is the most obvious, McCarthy’s more widely-noted achievement is to capture that feeling for space in terms that resonate with readers beyond those caught up in mere cowboy mythology, or in the earlier versions of male wandering that attract many young male readers. This second relation, between his heroes and their “natural” surroundings, is universally powerful enough in McCarthy’s work to have attracted a much broader audience, and increasing scholarship. He catches us trying to have our spaces without them turning into other people’s places. We want, each of us alone, to have our “country” as a field of movement that is nevertheless secure, our own place within unlimited possible space. McCarthy avoids direct psychology, and his characters live at the opposite end of the conscious/self-conscious spectrum from those characters of, for instance, Henry James. Nonetheless, reasonable inferences about McCarthy’s young men (always men), assure us that they assume those aspects of “country” suggesting limitless possibility at best, antinomian bloodbaths at worst. This transformation of “country,” from space to place, enacts a parallel movement in the book from philosophy to history. That central question about the human heart’s ability to transform “the stuff of creation” cannot be fully answered in the affirmative if history is to have any say at all at the end of the experiment; indeed, such an experiment would necessarily continue indefinitely, and so it is that the judge has his answer in music, in dance, in eternity. Yet, even a partial answer that yes, that heart has that power, will present itself on one level in not only the vague terms of myth, but also in the particular terms of history. So it is that the Epilogue demands both a mythic, and a historical, interpretation. The judge may go on dancing, but the rest of us are left to clean up the mess and mourn the dead. *Blood Meridian*’s plot hangs on history: the novel follows a character named “the kid” alongside the Glanton Gang, scalp hunters for hire to Mexican principalities in 1849. In this sense, the novel is true to a generic trope of the Western: lawless men (or lawful men in a lawless space) enact the violent subjugation of space until it becomes a place so constrained that it can no longer tolerate their inclusion. The Glanton Gang is based on historical figures indiscriminate in whom they scalped (their victims often included mestizo peasants), yet who were part of the official attempt to eradicate Native American Indians for the sake of Mexican townships. McCarthy makes it clear that we should not read this story merely as the specific history of manifest destiny in the American West and Mexican North; among the novel’s epigraphs, after all, he includes that *Yuma Daily Sun* item describing anthropological evidence of scalping in what is now Ethiopia—300,000 years ago. Nonetheless, *Blood Meridian* ends at a line in history beyond which the ageless violence of the gang will no longer be possible on the scale at which we find it. In many ways, the central figure of the novel is less the kid than Holden, the mysterious “judge” in name and in practice an immortal force of darkness rivaling both Ahab and the whale. Of what he is a judge, and by what authority beyond his own, we must puzzle over. Holden wants the kid under his wing, and he argues by a darker line Krishna’s position with Arjuna, that if the kid failed full participation in war, he failed his proper nature in a universe whose meaning is illusional. Holden spouts Nietzsche before Nietzsche’s time, insisting on the creative regeneration of human identity through bloodshed. This giant, an altogether hairless (like a malevolent outsized infant) enlightenment polymath who molests and murders children and drowns puppies, sits in judgment on the kid: “You sat in judgement on your own deeds. You put in your own allowances before the judgements of history and you broke with the body of which you were pledged a part and poisoned it in all its enterprise. Hear me, man. I spoke in the desert for you and you only and you turned a deaf ear to me. If war is not holy man is nothing but antic clay” (307). The judge’s use of the word “history” is larger than mine, of course: he means that passage of time comprehensible only at the scale of wheeling stellar bodies—and his immortal dancing form. What he certainly does not indicate is that constantly revised human attempt to agree on what happened, and why—let alone as part of some moral project. In fact, the latter is what the judge is accusing the kid of doing. Yet, for all the philosophical force embodied by the judge, he is based on a historical account of a “judge Holden” in Samuel Chamberlain’s My Confessions, a memoir that includes a stint with the real Glanton gang. Like the rest of the book, then, we must read him simultaneously in historical and ahistorical terms. The gang, the kid, and the judge are therefore the perfect historical test for the country in Blood Meridian—perhaps apart from whatever we might make of their common philosophical problem. The book is too violent to be boiled down to revisionist history, yet too complex to be, as one particularly ideological scholar would have it, a Reaganesque romp in American colonial killing (Beck). No matter how we read it, on moral matters, it remains thick and dark. But on what happens to country, we may get clearer as the end of the book’s main action gives way to the Epilogue. In the culmination of that action, the Glanton Gang is indeed run to ground, after much time and blood. Having avoided settling down but tracked by the forces of the very governments that once hired them, they uncharacteristically take over a fort, only to suffer a quick massacre by Yuma Indians. Those gang members that survive end up on the run, with less room to run in. It is then that a member of the gang named Toadvine is asked where he might go, and he complains, “You wouldn’t think that a man would run plumb out of country out here, would ye?” (285). A similar complaint ends McCarthy’s All the Pretty Horses. A hundred years after the Glanton Gang runs amok, John Grady Cole returns from his own violent trip to Mexico. Though his errands are remarkably less bloody and primitive than those of the previous book, they depend no less on his assumption of an open “country.” Like Toadvine and “the kid” he might be speaking for, John Grady depends on a sense of “country” as possibility. When his friend Lacey Rawlins suggests that, having come back with his dreams turned into nightmares, he might stay with him in Texas and get a job on an oilrig, his reaction indicates the persistence of the myth of Western space. With that hundred years passed since the Gang’s fenceless homicidal wandering, John Grady is no less possessed of that horse culture sense of limitless space in which to roam, even as he is puzzled by the limits he keeps seeing in it. His friend argues, “This is still good country.” John Grady replies, “Yeah. I know it is. But it aint my country.” Asked, “Where is your country?” John Grady can only reply, “I dont know…. I dont know where it is. I dont know what happens to country” (299). What do Toadvine and John Grady mean by “country”? One definition, the *American Heritage*, particularly suits McCarthy characters: “[a] region, territory, or large tract of land distinguishable by features of topography, biology, or culture.” This order is evident in these novels, though the last feature is initially marginal, at best: as *Blood Meridian*’s Judge Holden would have it, culture exists only as a flim-flam, as biology manifested in blood. To Holden, the more salient aspect of the country is a sense of space before it is rendered into “place”—before it can circumscribe what the heart might “try.” It is therefore necessary that McCarthy’s frequent and now famous descriptions of the country they cross indicate something apart from human comprehension, let alone human control. *Blood Meridian*’s gang traverses a mute cinder of a planet, something we hardly have language for. Even the mere “topo” in the above definition reflects our need to make spaces into places. As we see in the Epilogue, the enigmatic ending of *Blood Meridian* concerns itself with just this activity in the country. Comparing another repetition between these fifth and sixth novels, we add to our sense of “what happens to country.” Traveling across the desert in *Blood Meridian*, the kid finds human babies “hung [by Indians] from the broken stobs of a mesquite” tree (57). A hundred years later, John Grady rides across what could be the same territory and finds birds, impaled by the wind on the thorns of “roadside cholla” (73). From babies to birds: the violence is still there, but stepped down a few notches. We may continue to theorize “frontera,” and indeed see the continuing flux of claims and mix of cultures across the American West and Mexican North. But the contests are not so bloody there, not now, as they had been. Country, then, means the same thing across these novels in terms of potential space rendered into limiting places. Yet, the degree of violent freedom in that country has narrowed. So what has happened to effect this change? John Wegner points to war; the meanderings of McCarthy’s characters back and forth across the border between the United States and Mexico imply serious lack of historical knowledge on the part of those gringos (“Whose Story”; Overcoming). The sheer military force of our country—as a nation-state—effected much change in the more general “country” of McCarthy’s characters. (In his weaker moments, McCarthy gives us Mexican lecturers on this throughout The Border Trilogy.) Finally, however, Blood Meridian’s enigmatic Epilogue deepens our understanding of “what happens to country” to include a larger war against space and the freedom of all its inhabitants. The Epilogue is only half a page long. It begins, “In the dawn there is a man progressing over the plain by means of holes which he is making in the ground. He uses an implement with two handles and he chucks it into the hole and he enkindles the stone in the hole with his steel hole by hole striking the fire out of the rock which God has put there” (337). Harold Bloom reads the fire in this mysterious Epilogue as Promethean. Prompted by Peter Josyah to consider this action as “a process of digging holes, of setting dynamite to build a fence: the closing in of the West,” Bloom responds: No, no, no, that’s a very bad interpretation. That two-handed implement is, as I say, doing one thing and one thing only: it is striking fire which has been put into the rock, clearly a Promethean motif, and he is clearly contrasted with creatures who are either goulish [sic] human beings, if they are human beings, or already are, in fact, shades, looking for bones for whatever nourishment that might bring about…. I cannot see that as any kind of allegory of anything that has happened to the American West. (qtd. in Josyah 14-15) But the tool must be a post-hole digger, as McCarthy, or any reader acquainted with manual labor must recognize. And given the dual trajectories of the philosophical question of the heart’s will (particularly given the judge’s answer to it) and the historical movement that both informs the plot and is described by it, I see no reason not to read this passage in both mythic, and historical, terms. What Bloom is objecting to is the hitching of this Epilogue to a political plow; he rightfully sees that the sharpest edges of books are sullied and dulled by such treatment. Yet, claiming a mythic meaning for a passage does not preclude one from simultaneously, or at least alternatively, finding a historical moment that informs that passage—especially if the cumulative weight of that moment only adds to the larger significance of what is represented. The first part of Bloom’s interpretation derives soundly from the phrase “the fire out of the rock which God has put there” (337; my emphasis). That is fine, but a reader who has wielded a post-hole digger—which is a two-handed implement for digging holes—for more than a few minutes could not fail to connect this description of McCarthy’s with the simple act of digging holes for fence posts, or some other placement, such as a marker. (Sensibility, that ultimate requirement for good close reading, does not suffer from physical experience.) We need not choose between historical and mythical readings of McCarthy: he works in both areas, and the links between things that have indeed “happened to the American West” and the older stories echoing in McCarthy’s imagery simply add to the power, to the fullness and scope, of his achievement. It is regularly McCarthy’s practice to build onto history stories whose meanings reach a mythic level. Until some speeches in The Crossing hit the reader over the head a few times with their historical foundations, however, they usually reveal themselves in sufficiently opaque language that it would be ridiculous to then rule out mythic or other symbolic readings. We may return to the passage, then, with an eye toward both levels of meaning. The historical references in this passage are nothing if not Promethean, even as their evidence adds to Wegner’s point that history exerts unseen forces in McCarthy’s work. The activity described in the Epilogue refers to historical aftermath, however—to the culmination of years of violence, especially around ten years leading up to 1883 (although the Glanton Gang will have started much of it earlier). Because of the rapid temporal movement in the end of the main narrative, and details in the cryptic Epilogue itself, we can reasonably infer that the action of the Epilogue itself—the movement of its figures—takes place around 1883. That would be fifty years following the birth of “the kid,” and fifty before the birth of John Grady Cole. This Epilogue, then, hangs over all McCarthy’s work as a significant historical “meridian.” Before it, the Glanton Gang has wandered on horseback unconstrained by fences, across a largely pre-nomian space not even altered enough to warrant the cultural baggage of the term “wilderness.” The Gang’s massacres of peaceful Tigua Indians, as well as their assaults on small Mexican towns, certainly gives evidence of scattered forms of civilization. Indeed, in these acts the Gang performs an antinomian function. But Judge Holden’s regular arguments, quoting Nietzsche right and left, as well as the ease with which the Gang wanders, suggests that Gang’s movements constitute a last hurrah in this territory for blood unstaunched by even the most primitive codes of conduct. Other figures follow this man across the ground. They are “the wanderers in search of bones and those who do not search”—two groups behind the man digging holes. The first group is easily identified as gatherers of buffalo bones. The kid’s (or as the book calls him this late, “the man’s”) recent encounter with “bonepickers” (317) bolsters this identification. Indeed, Elrod, the doppelgänger whom the kid kills just before he finds the judge (and his death) in Griffin, is among these bonepickers. These “wanderers” (bonepickers) constitute the first group. The second group are either running new fence lines, or surveying the landscape. If fencing, they are working with fence posts enabled by the man digging; if surveying, they are placing some similar posts as markers. Either way, they accomplish this through the work of the first figure’s hole digging. (It is unnecessary to narrow our interpretation to fencing or surveying or even both; both have their evidence and both contribute to the same implications.) As for fencing, the meridian of the American West—in the sense of its division by fencing—occurred too chronologically close to the killing off of most of the American bison not to associate the two actions. As for surveying, that can enable fencing. In any case, this second group (“those who do not search”) has gone altogether missing in Bloom’s otherwise insightful reading. These men move haltingly in the light like mechanisms whose movements are monitored with escapement and pallet so that they appear restrained by a prudence or reflectiveness which has no inner reality and they cross in their progress one by one that track of holes that runs to the rim of the visible ground and which seems less the pursuit of some continuance than the verification of a principle, a validation of sequence and causality as if each round and perfect hole owed its existence to the one before it there on that prairie upon which are the bones and the gatherers of bones and those who do not gather. (337) Could these not then be surveyors? Whether they are leaving behind a visible demarcation across the land is debatable, though likely. A post-hole digger wrings a substantial amount of sweat from a man merely putting down markers, so a fence—something permanent to show for that labor—is more likely. As should become clear soon, though, such fencing may be running just apace of actual land grants and deeds; certainly it would be done according to a plan (or plat) and even something more conceptually important than the mere realization of a plat: “the verification of a principle.” Beneath the mythic meridian that is indeed quite compelling—of a Promethean figure stealing God’s fire—lies the bloodier meridian realized through historical operations: the gathering of the bones of exterminated buffalo, and the reckoning of the plats first imagined in the Land Ordinance of 1785, with a man now marking off the land. Whether through fencing or not, space is being turned into place. The first appearance of barbed wire in the West led to an astonishingly rapid change, not only in ranching practices, but in conflicts between large and small ranchers, ranchers and sheep herders, and ranchers and farmers (Milner 264-265; cf. McCallum, Webb). Partitioning off the land certainly could take place more easily after the elimination of animals that, in a fast-moving herd unaccustomed to being constrained in their movements, might wreck such fencing. Railroads paid for buffalo killing, and the government subsidized the killing of this animal so crucial to the lives of Plains Indians. Partitioning the land, however, is crucial to everyone attempting to take it from those Indians. Some hundred years earlier, a “West” divided into six-square mile portions of land was no longer confined to the imaginations of Eastern politicians; ranges and townships across the West were quickly set up along the plans imagined in the Land Ordinance of 1785.¹ Indeed, those “who do not gather” proceed behind the hole-digger in “less the pursuit of some continuance than the verification of a principle, a validation of sequence and causality as if each round and perfect hole owed its existence to the one before it” (337). What “validat[es]” this “sequence and causality”? The regular spacing of the holes. What “principle” is here “verifi[ed]”? That the space of the America West can indeed be transformed from the “embarrassment” referred to in one resolution by the Continental Congress, into a demarcated set of places.² The setting here is simply noted as “the plain.” That is not a desert, but more likely some place in the space of grassy plains extending from Canada all the way South toward the Texas Gulf: grass all along this area, with wells dug into the Ogallala Aquifer (which runs from North Texas to South Dakota), allowed cattlemen the food and water necessary for herds and farmers the water necessary for crops. This was the land settled most of all by fencing, and it was the first of the “frontier” to be planned out in the principled imagination of the Land Ordinance. The language of the Ordinance even suggests the mechanistic metaphors of McCarthy’s Epilogue, with its attention to temporal and spatial order. Here is the description in 1785 of the process by which marking off the land must attempt an accord with the theoretical division of that land by meridians and base lines: The lines shall be measured with a chain; shall be plainly marked by chaps on the trees and exactly described on a plat; whereon shall be noted by the surveyor, at their proper distances, all mines, salt springs, salt licks and mill seats, that shall come to his knowledge, and all water courses, mountains and other remarkable and permanent things, over and near which such lines shall pass, and also the quality of the lands. (Indiana Historical Bureau) In the description of the Epilogue, there are no trees to “chap,” nor any “mountains” to interrupt the progress of these workers. This would make it all the more likely that the work of surveyors would proceed with a delicate reckoning between sight and imagination, between the “principle” and the actual holes being dug in the ground. Whether or not the holes being dug will be filled with fence posts, the only way to mark a landscape bereft of trees with any reliable “lines” is to put holes in it. In the most open land, little in the way of “remarkable and permanent” variations could “come to [the] knowledge” of a surveyor; rather, the surveyor is freer to bring his “knowledge”—his false ordering of nature—to the ground. Would not Judge Holden be pleased at this? The killing of the American bison by private hunters and those contracted by the railroads resulted in their near extinction by 1883 (Milner 152). If a roof had been built over the southern plains in the early 1870’s, the American zoologist William Hornaday wrote, it would have been “one vast charnel-house.” During the fall of 1873 the corpses, stinking and rotting in the sun, lay in a line for forty miles along the north bank of the Arkansas River. William Blackmore, an English traveler, counted sixty-seven bodies in a space not covering four acres. The bodies were those of bison. (White 237; my emphasis) The year before the introduction of barbed wire, a buffalo hunter named George Reighard killed, on average, one hundred buffalo every day of his employment with an outfit hired for this purpose. This hunting trip took place in the Texas panhandle, in 1872: “Asked, years later, whether he felt pity for the animals as day after day he dropped his hundred, he replied no, he did not. ‘It was a business with me. I had my money invested in that outfit…. I killed all that I could’” (White 237). Recording this point of view in his chronicle of the slaughter, “Animals and Enterprise,” Richard White is understandably unable to avoid imposing just the kind of retrospection of regret that McCarthy generally avoids: Money and pity, these are the words that mark a great divide in the history of the American West. Reighard stood at a point where animals were only dollars on a hoof; those who later asked him about pity regarded animals as being worthy of concern within a human moral universe. (237; my emphasis) White’s “divide” suggests a line has been crossed, a meridian between what we like to think of as our more subtle moral order, and a more primitive one behind us. White also reminds us that another line existed in 1872, one less temporal than spatial, between two peoples: one people to whom animals are commodities, and another people to whom animals were equals. The Plains Indians, as well as the animals they depended on, were driven to near extinction within a decade of 1872. Much of the work toward this eradication was accomplished in the American Southwest well before the remains of Northwestern Lakota Sioux were rounded up into reservations such as Pine Ridge, South Dakota: the site of the Wounded Knee massacre. The intentional large-scale killing in the Southwest had begun almost half a century earlier, with the Glanton gang notable in the enterprise. It would be a mistake to suggest here that McCarthy’s novel is intended to evoke “pity,” to use Richard White’s word, over these events. Yet the realization of the imagined grid organizing the frontier, the advent of barbed wire to enclose portions of that grid, and the eradication (sometimes undifferentiated in the execution and more so in the results) of both the American bison and the American Indians, are coeval, as suggested by McCarthy’s language. Joseph Farwell Glidden patented barbed wire on October 27, 1873. By 1876—only three years after its introduction—2.84 million pounds of the stuff had been produced, and within four more years, that production had been dwarfed by 80.5 million pounds. “With barbed wire and the railroads, the cowboy’s days were numbered” (New Encyclopedia of the American West 80). Not only to cowboys still accustomed to open range ranching, but presumably more so to anyone on horseback riding in attempted disregard for the new order being set out on the land, barbed wire became known as “the Devil’s Rope” (Evan 72). Where, then, and when, do we locate the blood meridian—this singular circumscription presiding over McCarthy’s book? I have attempted to position several meridians, lines both philosophical and historical, abstract and visible, as likely referents: like suspects in a line-up, they seem to me to have had suspicious contact with one another. And I have also suggested that a chronological division operates here as well, dividing McCarthy’s books, and indeed significant moments in American history. What happens to country in Blood Meridian echoes in the books to follow, and in this country. What happens to country is that history constrains both its violence and its freedom. Perhaps this is why McCarthy, in one of only two interviews, sounds a bit like he’s complaining: There’s no such thing as life without bloodshed…. I think the notion that the species can be improved in some way, that everyone could live in harmony, is a really dangerous idea. Those who are afflicted with this notion are the first ones to give up their souls, their freedom. Your desire that it be that way will enslave you and make your life vacuous. (Woodward 31) The kid in Blood Meridian is born in 1833, John Grady Cole (and Cormac McCarthy) in 1933. The kid seems, at first, able to roam where he pleases, until the massacre of the filibusterers. From that point on, the Glanton gang rides on and on through a free arc of antinomian violence, until the external pressures of enclosing civilized authority, the natural boundaries even of the wide open west, and their own ironically persistent human tendency toward settling down lead them to “run plumb out of country” (285). Key coeval developments in fencing, plotting, extermination, and eventual settlement (or conquest) of the Southwest cluster around the ten years leading up to 1883—fifty years between the births of the kid and his much milder twentieth-century cousin, John Grady Cole. Perhaps, then, McCarthy closes his Blood Meridian at a line of division between a world without pity and a world consumed in it, yet nonetheless persistently cruel. Still, a more proper closing is less ambitious in its false orders, more poetic, and mysterious; McCarthy’s image alone: “He strikes fire in the hole and draws out his steel. Then they all move on again” (337). Notes 1 The Land Ordinance of 1785 was signed into law eleven years later, by George Washington, as the Land Act of 1796. As Rod Squires argues, “The Ordinance of 1785 has, rightly, been given importance as the first piece of legislation that addressed the question of how should a nation proceed to subdivide the land surface. But the provisions of the Ordinance were very limited, in terms of the area it affected and in terms of many of the characteristics so familiar to land surveyors. When a new government was established the Ordinance had no legal effect. The public land surveys were continued only after Congress enacted a Land Act in 1796, legislation that should be accorded more attention.” In the spirit of abstraction that caused those insisting on “ideal lines” no “embarrassment,” I will nonetheless refer to the original Ordinance. My point is that geometry ruled the geography. As McCarthy’s practice also sets up striking chronological divisions, it seems fitting—because ironic—that by merely fudging a couple of years, I can here point to the Land Ordinance as preceding McCarthy’s Epilogue by some hundred years. 2 While the revolution was still in progress, wrangling over western lands persisted, as states that had extensive grants from Great Britain wanted to keep them, while states such as Maryland lacked such grants and therefore wanted a more equitable division through the new Federal government. Maryland’s reluctance to sign the Articles of Confederation led the Continental Congress to a resolution urging these states to remove the “embarrassment respecting the western country.” That “embarrassment” has everything to do with the move in 1785, and more forcefully in 1796, away from the vissicitudes of land ownership according to precedents and grants arising without a larger organizing feature: divide things up neatly ahead of time and you might expect less wrangling over the spoils (September 6, 1780 resolution qtd. in Goble). Works Cited ---. “Whose Story Is It?: History and Fiction in Cormac McCarthy’s *All the Pretty Horses*.” *Southern Quarterly* 36.2 (Winter 1998): 103-110.
Distal-less and Dachshund Pattern both Plesiomorphic and Apomorphic Structures in Chelicerates: RNA Interference in the Harvestman Phalangium opilio (Opiliones) Citation Permanent link http://nrs.harvard.edu/urn-3:HUL.InstRepos:10512167 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#OAP Share Your Story The Harvard community has made this article openly available. Please share how this access benefits you. Submit a story. Accessibility Distal-less and dachshund pattern both plesiomorphic and apomorphic structures in chelicerates: RNA interference in the harvestman Phalangium opilio (Opiliones) Prashant P. Sharma\textsuperscript{1,2,4}, Evelyn E. Schwager\textsuperscript{2}, Gonzalo Giribet\textsuperscript{1,2}, Elizabeth L. Jockusch\textsuperscript{3}, Cassandra G. Extavour\textsuperscript{2} \textsuperscript{1}Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, United States \textsuperscript{2}Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, United States \textsuperscript{3}Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road, Storrs, CT 06269, United States \textsuperscript{4}Corresponding author. Email: psharma@fas.harvard.edu Abstract The discovery of genetic mechanisms that can transform a morphological structure from a plesiomorphic (=primitive) state to an apomorphic (=derived) one is a cardinal objective of evolutionary developmental biology. However, this objective is often impeded for many lineages of interest by limitations in taxonomic sampling, genomic resources, or functional genetic methods. In order to investigate the evolution of appendage morphology within Chelicerata, the putative sister group of the remaining arthropods, we developed an RNA interference (RNAi) protocol for the harvestman *Phalangium opilio*. We silenced the leg gap genes *Distal-less (Dll)* and *dachshund (dac)* in the harvestman via zygotic injections of double-stranded RNA, and used *in situ* hybridization to confirm RNAi efficacy. Consistent with the conserved roles of these genes in patterning the proximo-distal axis of arthropod appendages, we observed that embryos injected with *Dll* dsRNA lacked distal parts of appendages and appendage-like structures, such as the labrum, the chelicerae, the pedipalps, and the walking legs, whereas embryos injected with *dac* dsRNA lacked the medial podomeres femur and patella in the pedipalps and walking legs. In addition, we detected a role for these genes in patterning structures that do not occur in well-established chelicerate models (spiders and mites). *Dll* RNAi additionally results in loss of the preoral chamber, which is formed from pedipalpal and leg coxapophyses, and the ocularium, a dorsal outgrowth bearing the eyes. In one case, we observed that an embryo injected with *dac* dsRNA lacked the proximal segment of the chelicera, a plesiomorphic podomere that expresses *dac* in wild type embryos. This may support the hypothesis that loss of the cheliceral *dac* domain underlies the transition to the two-segmented chelicera of derived arachnids. Keywords: Gene silencing; RNAi; Arachnida; Chelicerata; arthropod leg; leg gap genes Introduction The diversity of arthropod appendages has prompted an historic, fascinating series of debates that span the homology of various appendage types (Snodgrass 1938; Boudreaux 1987; Boxshall 2004), the fate of Cambrian arthropods’ “great appendages” (Weber 1952; Rempel 1975; Scholtz 1997, 2001; Budd 2002; Maxmen et al. 2005; Jager et al. 2006; Brenneis et al. 2008), the nature of the mandible (Anderson 1973; Manton 1977; Boudreaux 1987), and the implications of all of these for arthropod phylogeny. In complement to paleontology and morphology, gene expression and function data have become integral to deciphering arthropod evolution. Specifically, the suite of genes that patterns the proximo-distal axis of appendages (Distal-less [Dll], dachshund [dac], and the cofactors homothorax [hth] and extradenticle [exd]—commonly referred to as “leg gap” genes) has been utilized as an independent body of evidence for testing evolutionary hypotheses pertaining to appendages (reviewed by Angelini and Kaufman, 2005). In several cases, studies of leg gap gene expression and/or function have supported earlier hypotheses based on morphological evidence, such as the gnathobasic nature of the mandible (Panganiban et al. 1994, 1995; Scholtz et al. 1998; Prpic et al. 2001), the ancestral bipartite structure of the arthropod leg (González-Crespo and Morata 1996; Dong et al. 2001; Abzhanov and Kaufman 2000; reviewed by Angelini and Kaufman 2005; Janssen et al. 2010), and the serial homology of mandibulate head appendages (Rieckhof et al. 1997; Dong et al. 2001, 2002; Ronco et al. 2008). In other cases, typified by the dispute over the nature of the labrum, leg gap gene data do not unambiguously favor one hypothesis over another (Popadić et al. 1998; Scholtz 1997; reviewed by Scholtz and Edgecombe 2006). The leg gap genes serve to regionalize the arthropod leg, conferring proximal (hth and exd), medial (dac), and distal (Dll) identities (Sunkel and Whittle 1987; Cohen and Jürgens 1989; Mardon et al. 1994; González-Crespo and Morata 1996; Lecuit and Cohen 1997; Rieckhof et al. 1997;dong2001;dong2002;ronco2008). However, these genes also play a role beyond patterning the PD axis. For example, *Dll* is known to have additional roles in patterning sensory organs and bristles (Sunkel and Whittle 1987; Cohen and Jürgens 1989; Mittmann and Scholtz 2001; Williams et al. 2002), sexually dimorphic non-appendage outgrowths (Moczek and Nagy 2005; Moczek et al. 2006; Moczek and Rose 2009), and even antero-posterior gap gene function in spiders (Pechmann et al. 2011). Similarly, *dac* patterns elements of the central nervous system, particularly photoreceptors of insect compound eyes (Mardon et al. 1994). Nevertheless, barring *Dll*, evolutionary inference of leg gap gene activity remains limited by the concentration of functional analyses within hexapods. For example, while *dac* orthologues are inferred to pattern the medial regions of legs of all panarthropods based on expression domains (Janssen et al. 2010), *dac* knockdown phenotypes have only been observed in a handful of winged insects. Chelicerales, the putative sister group to the remaining arthropods (mandibulates), is a diverse lineage that includes Arachnida (e.g., spiders, mites, scorpions), Merostomata (horseshoe crabs and the extinct sea scorpions [Eurypterida]), and possibly Pycnogonida (sea spiders). Due to the phylogenetic significance of chelicerates, developmental processes in chelicerate model organisms are greatly relevant to evolutionary inference. For example, the retention of the chelicerate deutocerebral appendage, demonstrated in the mite *Arachozetes longisetosus* and the spider *Cupiennius salei*, has supported a particular interpretation of arthropod segmental homologies (Damen and Tautz 1998; Telford and Thomas 1998; Hughes and Kaufman 2002; Scholtz and Edgecombe 2006). Investigation of the *Notch* pathway in the spider *Cupiennius salei* has similarly demonstrated conservation of pathways in segmentation processes of both the body and the appendages (Stollewerk et al. 2003; Prpic and Damen 2009). Four of the 12 extant orders of euchelicerates (Xiphosura + Arachnida) have been studied with respect to leg gap genes: horseshoe crabs (Xiphosura), mites (Acari), spiders (Araneae), and harvestmen (Opiliones). Horseshoe crabs are the least studied in this regard: only protein expression of Dll is known in *Limulus polyphemus* (Mittmann and Scholtz 2001). In mites, leg gap gene data are limited to expression and function of Dll (Thomas and Telford 1999; Khila and Grbic 2007). Dll acts as a typical leg gap gene in *Tetranychus urticae*: a parental knockdown of Dll results in the truncation of appendages due to the loss of distal leg structures, as in insects (Dong et al. 2001; Rauskolb 2001; Khila and Grbic 2007). The expression of all four leg gap genes has been profiled in multiple spider species (Abzhanov and Kaufman 2000; Schoppmeier and Damen 2001; Prpic et al. 2003; Prpic and Damen 2004; Pechmann and Prpic 2009; reviewed by Pechmann et al. 2010). As with mites, functional data in the spider *Cupiennius salei* (obtained via zygotic RNAi) have focused on the activity of Dll, demonstrating the conserved role of this gene in appendage axis formation (Schoppmeier and Damen 2001). Additionally, parental RNAi in another spider species, *Parasteatoda tepidariorum*, has demonstrated an intriguing novel role for Dll as an anterior-posterior axis gap gene that regulates the segmentation of the body (Pechmann et al. 2011). Specifically, a parental knockdown of Dll results in the loss of one to two body segments (bearing the first walking leg pair or the first and second walking leg pairs). In contrast to these multiple studies of the role of Dll, no functional data are available for dac, hth, or exd in any chelicerate. The most recent addition to the suite of chelicerate study organisms is the harvestman *Phalangium opilio*, for which we previously profiled the expression domains of the leg gap genes (Sharma et al. 2012b). These data demonstrated that leg gap gene expression in the harvestman is largely comparable to that of the spider. Harvestmen may be considered to represent a lineage of “primitive” arachnids (like scorpions), as they bear a number of plesiomorphic structures not observed in spiders or mites. Their early appearance in the fossil record and placement in most chelicerate phylogenies enables phylogenetic polarization of developmental data observed in the other chelicerate models (Dunlop 2010; reviewed in Giribet and Edgecombe 2012; Sharma et al. 2012a) (Fig. 1A). Several harvestman structures that express leg gap genes do not occur in spiders or mites. First, the preoral chamber is formed from the pedipalpal and first leg pair endites, and is exclusive to harvestmen and scorpions (although the preoral chambers of scorpions also include the endites of the second walking legs). This structure facilitates manipulation of food particles. In contrast to derived arachnids, scorpions and harvestmen do not have suctorial mouthparts; they feed using the proximal-most parts of their limbs, the coxapophyses (coxal endites) of the pedipalps and first pair of walking legs (Fig. 1B, 1C). Previously, we reported that these two pairs of endites express Dll in *P. opilio* prior to outgrowth (Sharma et al. 2012b), in a manner comparable to the spider “maxilla” (a structure formed from the pedipalpal coxal endites, which also express Dll and are retained in adults [Schoppmeier and Damen 2001; Pechmann et al. 2010]), the gnathendites of crustacean mandibles (which are also used in feeding; Panganiban et al. 1995; Scholtz et al. 1998), and the labial and maxillary endites of insects (Giorgianni and Patel 2004; Jockusch et al. 2004; Angelini et al. 2012a). These data suggest that Dll is involved in coxal endite outgrowth in both chelicerates and pancrustaceans. Second, the ocularium is a dorsal mound that bears the single pair of eyes in Phalangida (the non-cyphophthalmid harvestmen; Giribet et al. 2010) (Fig. 1B). This structure is postulated to result from coalescence of a pair of Dll domains in the eye fields (specifically, the semilunar grooves; Sharma et al. 2012b). Eye mounds have evolved independently in several chelicerate lineages, such as pycnogonids and harvestmen. The outgrown nature of the ocularium suggests cooption of Dll to the development of this structure, given that in other arthropods, Dll patterns non-appendage outgrowths of the body wall, such as beetle horns (Moczek and Nagy 2005; Moczek et al. 2006; Moczek and Rose 2009). Third, harvestmen bear a three-segmented chelicera, which occurs in a grade of chelicerate orders leading to Arachnida (e.g., Xiphosura, Eurypterida, Pycnogonida), as well as some extant arachnid orders (e.g., Scorpiones, Opiliones; reviewed by Sharma et al. 2012b) (Fig. 1B). This disposition of cheliceral types has resulted in the reconstruction of the three-segmented chelicera as a symplesiomorphy (Dunlop 1996; Wheeler and Hayashi 1998; Giribet et al. 2002; Shultz 2007). The proximal segment of this appendage strongly expresses dac in the harvestman. In contrast, dac is not expressed in the chelicerae of spiders, which are two-segmented (as in most derived arachnids). Based on these observations, we previously postulated that a loss of the dac domain could represent the genetic mechanism for the evolutionary transition from the three- to the two-segmented cheliceral type (Sharma et al. 2012b). To date, the functional significance of the expression domains of Dll and dac in chelicerate orders with the plesiomorphic cheliceral type has not been tested. Functional genetic testing is infeasible in many of these groups, which may either lack structures of interest (e.g., horseshoe crabs do not have a preoral chamber) or are intractable for reasons pertaining to life history (e.g., scorpions give live birth after a gestation period lasting several weeks to months). However, the recently established harvestman model organism P. opilio possesses all aforementioned structures of interest, and is tractable for laboratory studies (Sharma et al. 2012a, b). Here we describe methods for gene silencing in Phalangium opilio via zygotic injection of double stranded RNA (dsRNA). We report the conserved functions of Dll and dac as canonical leg gap genes in the pedipalps and legs. We additionally observe that knockdown of Dll interferes with the development of the preoral chamber’s coxal endites and the ocularium. In a single embryo, we observe that a knockdown of dac results in a two-segmented chelicera lacking the proximal segment, suggesting that the evolutionary transition from the three- to the two-segmented chelicera is achieved by the loss of the dac domain, and thus, of the proximal segment. Materials and Methods Embryo collection and preparation Adults of Phalangium opilio (Arachnida, Opiliones, Eupnoi, Phalangiidae) were hand collected between 9:00 PM and 3:00 AM from various sites in Weston, Massachusetts, and Storrs, Connecticut, USA in June through August of 2012. Adults were maintained and embryos collected as previously described (Sharma et al. 2012a). Embryo preparation for RNAi followed a modified protocol for the spider C. salei (Prpic et al. 2008). After 3-4 days of development, a clutch of embryos was dechorionated in 50% bleach solution and arranged into 8 × 8 grids on an agar dish. Glass cover slips (22 mm × 22 mm), previously coated with “heptane glue” (made by dissolving double-sided Scotch brand adhesive tape into heptane) and dried to create a layer of adhesive, were lowered onto each grid. In this manner, each clutch was approximately divided into three groups: 60% of the clutch was designated for injection with dsRNA for the gene of interest, 20% for injection with dsRNA for DsRed (exogenous dsRNA), and 20% for uninjected controls. This experimental design loosely follows that of Schoppmeier and Damen (2001). Like spider embryos, harvestman embryos contract 3-7 days after egg laying, forming a peri-vitelline space filled with peri-vitelline fluid (Juberthie 1964). Embryos were allowed to develop in deionized water until the peri-vitelline space was observed. Embryos with a clear peri-vitelline space were immediately prepared further for injection (see below). Gene identification, cloning, and synthesis of dsRNA Identification of Po-Dll and Po-dac using a developmental transcriptome of P. opilio was previously described (Sharma et al. 2012b). Templates for dsRNA synthesis were generated from cDNA as follows: Both genes were amplified by PCR using gene-specific primers (GSP) with an added linker sequence (these primers were previously used for riboprobe synthesis; sequences published in Sharma et al. 2012b). PCR products were cloned using the TOPO® TA Cloning® Kit with One Shot® Top10 chemically competent E. coli (Invitrogen, Carlsbad, CA, USA), following the manufacturer’s protocol, and their identities verified by sequencing. dsRNA synthesis was conducted with the MEGAscript® T7 kit (Ambion/Life Technologies, Grand Island, NY, USA) from amplified PCR product (above), following the manufacturer’s protocol. The synthesis was conducted for 4h, followed by a 5 min cool-down step to room temperature. A LiCl precipitation step was conducted, following the manufacturer’s protocol. dsRNA quality and concentration were checked using a Nanodrop-1000 spectrophotometer (Thermo Scientific, Wilmington, DE, USA) and the concentration of the dsRNA was subsequently adjusted to 3.85-4.00 µg/µL. **Embryo injection** Upon the appearance of the perivitelline space, embryos were dehydrated at room temperature for 30 min. Subsequently, embryos were immersed in halocarbon oil 700 (Sigma-Aldrich, St. Louis, MO, USA). For injection, food-grade green dye was added to the dsRNA at a 1:20 dilution in order to visualize insertion of dsRNA. Microinjection needles were prepared from glass capillaries (1/0.58mm, 1B100F-4, World Precision Instruments, Sarasota, FL) using a micropipette puller (P-97, Sutter Instruments Co., Novato, CA, USA), and were backloaded with tinted dsRNA solution. Microinjections were performed on a Lumar stereomicroscope (Zeiss, Oberkochen, Germany) equipped with a micromanipulator (MMO-202ND, Narishige, Tokyo, Japan) coupled to a microinjection unit (IM 300, Narishige, Tokyo, Japan). dsRNA was injected into the peri-vitelline space. Optimal pressure and injection time were empirically determined. Because harvestman embryos are under high internal pressure, injected solution is frequently ejected from the embryos upon the retraction of the capillary. However, pre-injection dehydration greater than 30 min often leads to embryonic death. Consequently, our injection technique exploits a particular feature of eupnoid harvestman embryos: the eggs of *P. opilio* grow in size during development, requiring contact with a hydrated surface to do so (Gnaspini 2007). Therefore, injections were performed so as to leave a droplet of dsRNA solution immediately outside the embryo, in contact with the injection site. In 1-2 days, the embryos were observed to absorb more of the solution than could initially be injected into the peri-vitelline space, as inferred from the increasing intensity of green color in the yolk of the embryos and the decreased size of the droplets. *Embryo hatching and imaging* Following injection, embryos were allowed to develop at 28 °C. To remove oil and glue, embryos were washed with heptane. To investigate gene expression, embryos were fixed and *in situ* hybridization was performed as previously described (Sharma et al. 2012a). Embryos were counterstained with Hoechst 33342 1 µg/ml (Sigma-Aldrich, St. Louis, MO, USA). Images were captured using an AxioCam HrC and an AxioZoom V16 stereomicroscope driven by Zen 2011 (Zeiss, Oberkochen, Germany). Leg mounts were imaged using an AxioImager compound microscope driven by AxioVision v 4.8.2 (Zeiss, Oberkochen, Germany). Embryos were induced to hatch by washing briefly in heptane and subsequently with deionized water. Embryos injected with $DsRed$-dsRNA were allowed to hatch normally. Embryos with severe $Dll$ knockdown phenotypes were artificially hatched by manual dissection, using the position of the eyes and the degree of sclerotization (in comparison with control embryos) as indicators of completion of embryonic development. Live hatched embryos were immediately fixed in 96% EtOH. Images were captured using an HrC AxioCam and a Lumar stereomicroscope driven by AxioVision v. 4.8.2 Zeiss (Oberkochen, Germany). Results RNAi in *Phalangium opilio* Eight clutches (n = 710 viable embryos) were subjected to the procedures described above and injected with tinted *DsRed*-dsRNA in order to optimize the injection protocol. Embryos injected with tinted dsRNA solution were observed to absorb the color, which concentrated in the yolk. Those embryos that survived the injection procedure (see below) developed normally until hatching (data not shown), showing that neither the injection procedure, nor exogenous nucleic acids, nor the buffer used for the solution impeded normal development. Subsequent to protocol optimization, an additional five clutches (n = 454 viable embryos) were subsequently used in RNAi experiments (Table S1). Zygotic injections induced significant mortality in *P. opilio* embryos, with survivorship ranging from 45-59% in various experimental treatments (Fig. 2; Table S1). However, survivorship of uninjected embryos glued to cover slips under oil was also variable (46% in *Dll* experiments; 87% in *dac* experiments). This may be attributable to intrinsic variability in clutch quality (some clutches of wild caught *P. opilio* have smaller eggs and high mortality rates even without dechorionation, with clutch quality declining markedly toward the end of the season; data not shown). This variance may also reflect our accruing experience with handling *P. opilio* embryos, although the experiments were conducted in parallel. RNAi of *Po-Dll* *In situ* hybridizations for *Dll* on embryos with strong *Dll* loss of function phenotypes (described below) showed no *Dll* expression in any of the wild type domains (Fig. 3A), confirming that our RNAi treatment effectively abrogated Dll transcript accumulation. Of the embryos that survived injections of Dll dsRNA, 45% (n = 27) underwent a dramatic reduction in length of multiple prosomal appendages. In 89% of embryos with phenotypes (n=24), all prosomal appendages were shortened or nearly missing, retaining only the coxa, or the coxa and some of the trochanter (Fig. 4C, 4D). No labrum was observed in these embryos (Fig. 3B). We interpret these phenotypes as strong loss of function phenotypes of Dll. In the remaining 11% (n=3) of embryos with phenotypes, we observed a weak (or mosaic) phenotype, wherein only some appendages were shortened, typically only on one side (Fig. 5B, 5C). Among severe Dll RNAi phenotype embryos, in contrast to endites in DsRed-dsRNA injected embryos (Fig. 4B), the pedipalpal and L1 endites did not undergo proximodistal elongation. As a result, the mouth was exposed, and the preoral chamber did not form (Fig. 4D, S1). In DsRed-dsRNA injected embryos, outgrowths of these endites formed a wild type preoral chamber (Fig. 4B). In addition, embryos with strong phenotypes featured a reduction of the ocularium, in contrast to DsRed-dsRNA injected embryos, which bore a prominent ocularium (Fig. 4A). In the most extreme case, the eyes were disposed flatly onto the prosomal dorsal scutum (Fig. 4C). In wild type P. opilio embryos, dac is expressed at early stages in the central nervous system and posterior terminus, and at later stages in the trochanter and femur of the pedipalps and legs, and the proximal chelicera (Sharma et al. 2012b; Fig. 5A). In contrast, in Dll-RNAi embryos, dac was either absent (presumably due to the absence of appendage tissue; Fig. 5B) or, in those truncated appendages that did form, expressed in the distal-most portion, i.e., in the trochanter (Fig. 5B, arrowhead). In limbs that lacked the trochanters and thus consisted only of the coxa, dac expression was not observed in the appendages at all (Fig. 5B; non-specific staining in the termini of the coxae is due to cuticle deposition, but dac is not expressed in this region in earlier stages, as in the pedipalpal coxae in Fig. 5B). Non-appendage dac domains, including in the central... nervous system and the posterior growth zone, were not affected (Fig. 5B). In embryos with weak phenotypes, *dac* was consistently expressed in the medial appendage segments (Fig. 5C, 5D). **RNAi of Po-dac** In order to verify *dac* knockdown, we performed *in situ* hybridizations for *dac* on embryos injected with *dac* dsRNA (Fig. 6). Like uninjected embryos, *DsRed*-dsRNA injected embryos displayed the previously reported (Sharma et al. 2012b) *dac* expression domains in the nervous system, growth zone, and proximal chelicera, and the trochanter, femur, and proximal patella in legs and pedipalps. In contrast to *DsRed*-dsRNA injected embryos (Fig. 6A), *dac*-RNAi embryos typically lacked *dac* expression in the walking legs and pedipalps. However, some embryos retained *dac* expression in the pedipalps (Fig. 6C), and all embryos examined showed *dac* expression in the proximal segment of the chelicerae at levels comparable to those in control chelicerae, even when *dac* expression domains were disrupted or lost in other appendages (Fig. 6B, 6C). Of the embryos that survived injections of *dac* dsRNA, 24 % (n = 16) underwent loss of one or more segments in the legs and pedipalps (Fig. 7). Determination of segmental identity was based on the shape of the podomeres, as follows. The trochanter is a short podomere with the length approximately equal to the width. The femur is an elongated (i.e., high length-to-width ratio) segment that is wider distally than proximally. The patella of the legs is the only podomere that has a curvature in its shape, forming the “double knee” characteristic of arachnids. The tibia is of approximately cylindrical shape, with its greatest width in the center of its length. The metatarsus and tarsus are the narrowest of all podomeres, and the tarsus is differentiated by the distal tarsal claw and being the longest podomere. We note that the segmental identities are inferences based on shape and on *dac* expression in wild type embryos; presently, segment-specific markers are not known for embryonic appendage segments in harvestmen. In two of these 16 embryos (12.5%), we observed that legs were missing a single segment corresponding to the patella, and the pedipalpal patella was either missing or reduced. We interpret this as a weak *dac* loss of function phenotype (Fig. 7E-F). In the remaining 14 embryos (87.5%) the legs and pedipalps lacked two segments, corresponding to the patella and femur; we interpret this as a strong *dac* loss of function phenotype (Fig. 7H-I). The total length of each appendage is reduced as a consequence of these losses, with dramatic shortening of pedipalps and all legs (Fig. 7, S2). Among the legs of embryos that showed strong phenotypes, the observed length difference (with respect to the length of the segments inferred to be missing) corresponded approximately to the combined length of the femur and patella (deviation from expected length difference: 2-15%). Among the pedipalpi of both strong and weak phenotype embryos, the reductions varied much more from expected length differences (up to 60%), which could be attributable to incomplete podomere deletions (e.g., reduced/fused patella in Fig. 7E; possible retention of portion of patella at the distal end of the tibia in Fig. 7H). Fifteen of the 16 embryos (93.8%) with segmental losses in other appendages bore a three-segmented chelicera comparable to control chelicerae (Fig. 7, compare A and D). However, in a single embryo (6.2%) with a strong *dac* loss of function phenotype, the chelicerae symmetrically lacked the proximal segment and were shorter in length (Fig. 7D, compare A and G). Discussion Two motivations underlie the recent pursuit of *Phalangium opilio* as a system for evolutionary developmental study: taxon sampling and character sampling. First, studies of chelicerate development have largely emphasized two orders: spiders and mites. These lineages have enabled comparisons of developmental mechanisms with the other rami of the arthropod tree of life (pancrustaceans and myriapods) (e.g., Prpic et al. 2003; Prpic and Damen 2009; Janssen et al. 2010), but do not suffice to enable polarization of characters within Chelicerata. Study of a member of the chelicerate orders displaying plesiomorphic characters (e.g., book gills, three-segmented chelicerae), and attendant determination of ancestral states, is of particular interest in cases where (1) only one of the two current model lineages demonstrates an unusual developmental trait, exemplified by the role of *Dll* as a gap gene in a spider, but not in a mite (Khila and Grbic 2007; Pechmann et al. 2011); and (2) when both spiders and mites (as well as other derived orders) share a state that is not observed in other chelicerate orders, exemplified by the two-segmented chelicera that lacks a *dac* domain (Prpic and Damen 2004; Pechmann and Prpic 2009; Sharma et al. 2012b). Second, *P. opilio* has several morphological characters that do not occur in well-established chelicerate species, but are of biological interest. These include the greatly elongated walking legs characteristic of many Opiliones; the numerous tarsomeres (tarsal articles) that subdivide the tarsi, enabling prehensility and grasping; sexually dimorphic cheliceral armature (which also occurs in many non-model spider species); and repugnatorial glands for repelling potential predators. Allometric growth of the appendages is of particular interest in the context of developmental genetics (see for example Mahfooz et al. 2004, 2007). In the present study, we thus endeavored to develop functional genetic techniques in *P. opilio* for evolutionary inference and study of development in chelicerates. We utilized *Dll* and *dac* as case studies for testing the effectiveness of RNAi and demonstrate both conserved and derived roles of leg gap genes in this group. **Conserved roles of Dll and dac as leg gap genes** Truncation of the distal limb is the archetypal *Dll* phenotype in arthropods, and this has been corroborated in chelicerates (Cohen and Jürgens 1989; Beermann et al. 2001; Prpic et al. 2001; Schoppmeier and Damen 2001; Khila and Grbic 2007). However, identities of deleted segments in the chelicerate leg can only be inferred from spider data, based on embryonic gene expression patterns. In the spider, zygotic knockdown of *Dll* results in the loss of the leg distal to the trochanter, as inferred from the expression of *dac* in *Dll* knockdown embryos (Fig. 4 of Schoppmeier and Damen, 2001). Consistent with these data, we obtained harvestman *Dll* RNAi phenotypes with severe truncations in the distal limbs. As we were able to rear these embryos past the point of podomere formation, and even to assisted hatching, we were able to observe that only the coxa, or sometimes the coxa and trochanter, were retained in limbs with the strongest phenotypes. The loss of the femur and other distal podomeres is consistent with the expression of *Po-Dll* in both spiders and harvestmen. Furthermore, the loss of the trochanter, which does not express *Dll* in later stages, suggests that our RNAi experiments disrupted *Dll* activity at an earlier stage in development. Consistent with this interpretation, *dac* expression in appendages of *Dll* RNAi embryos is restricted to the trochanter (where it is normally expressed) when this segment is retained. In severe phenotypes wherein trochanter outgrowth is lost, *dac* expression is not observed in the appendages at all, suggesting that RNAi in these embryos disrupted Dll activity and prevented outgrowth prior to the regionalization of the appendages (Fig. 5B, left side of embryo). The expression of dac in wild type early stage embryos of both spiders and harvestmen was reported to be restricted to the trochanter and femur (Abzhanov and Kaufman 2000; Prpic and Damen 2004; Pechmann and Prpic 2009; Sharma et al. 2012b). However, in later stages of development, we observed that P. opilio embryos expressed dac in the proximal patella of all legs and the pedipalp as well (Fig. 5A). This expansion of the dac domain into the patella was previously overlooked in the harvestman, as only earlier developmental stages (comparable to the spider embryos in studies discussed above) were investigated (Sharma et al. 2012b). The overlap between the Dll and dac domains is therefore more extensive than previously thought. Consistent with these expression patterns, weak dac RNAi phenotypes exhibit a loss of the patella in the legs and pedipalp, whereas strong phenotypes exhibit a loss of both the patella and the femur in these appendages (Fig. 7). Our determinations of which segments were lost in dac phenotypes are inferences based on the shape of the podomeres and the reduced total length of the appendage, the latter disfavoring an alternative explanation based exclusively on segmental fusions. Nevertheless, the assignations of segmental identity would benefit from corroboration by gene expression studies. One way to test the identities of the podomeres would be to utilize exd, which is expressed as a distal ring in the patella of wild type embryos, as a marker for this segment; however, we were unable to perform this test due to limitations in obtaining P. opilio embryos. We presently do not know of other appendage patterning genes that would serve as reliable markers of segmental identity in the harvestman. Moreover, because spiders possess two paralogs of hth and exd, each of which has a unique suite of expression domains (reviewed by Pechmann et al. 2010), the spider model may be of greater utility for this purpose. Sharma et al. Page 18 of 39 This study nonetheless demonstrates two curious aspects of dac activity in the harvestman leg. First, a significant portion of the Dll domain overlaps the dac domain in the harvestman. Second, this overlap is dynamic, as the dac domain expands into the patella in later stages, a new observation not described earlier in chelicerates. A similar case has been reported in the beetle Tribolium castaneum, which bears two rings of dac in the legs (Prpic et al. 2001). In early stages, a single Tc-dac domain is proximal to the Tc-Dll domain and corresponds to the more proximal of the two dac rings. Later in development, the distal ring of Tc-dac expression arises within the Tc-Dll domain. Upon completion of appendage formation, the distal Tc-dac domain becomes significantly larger and overlaps with the Tc-Dll domain. Prpic et al. (2001) contended that the distal domain of dac comprised the primordia of the femur and tibiotarsus, and the proximal domain of dac likely comprised the coxal primordium. Knockdown phenotypes of T. castaneum at metamorphosis (Suzuki et al. 2009; Angelini et al. 2012b) show that strong dac phenotypes have appendages with deletions of the distal femur, the entire tibia, and the proximal tarsomeres, which correspond to the distal embryonic dac domain described previously (Prpic et al. 2001). However, the proximal segments coxa and trochanter are not affected even in severe dac phenotypes, suggesting that the proximal dac domain in T. castaneum is not required for metamorphic appendage patterning. Moreover, strong Tc-Dll RNAi phenotypes also undergo severe truncations of the limb, up to the proximal part of the femur; the Tc-Dll RNAi deletion domain overlaps the entire distal Tc-dac domain, which does act as a leg gap gene (Angelini et al. 2012b). Functional data for dac activity in embryos of the milkweed bug Oncopeltus fasciatus are comparable to those of metamorphic Tribolium: knockdown of Of-dac results in the loss of the tibia and truncation of the femur in severe phenotypes, whereas knockdown of Of-Dll results in the loss of all structures distal to the femur (Angelini and Kaufman 2004). Thus, in both the beetle and the hemipteran, the domain deleted in response to RNAi targeting *dac* lies almost entirely within the domain deleted in response to *Dll* knockdown, as in *P. opilio*. We thus observe similarities in *dac* activity in beetles, true bugs, and harvestmen. However, we note that limitations in taxonomic sampling make inferences of *dac* domain evolution across arthropods tenuous: aside from *P. opilio*, functional data on *dac* function in arthropod appendage development are available only from the winged insects (*D. melanogaster, O. fasciatus, T. castaneum*, and onthophagine beetles; Moczek and Rose 2009). Nevertheless, our data support the conserved roles of *Dll* and *dac* as leg gap genes during limb development in *P. opilio*. *Dll functions in development of the preoral chamber in the harvestman* We previously reported expression domains of *Dll* in the pedipalpal and L1 endites in *P. opilio* and speculated that *Dll* was required to form the preoral chamber (Sharma et al. 2012b). The present study supports this hypothesis, as we observed that individuals with severe *Dll* RNAi phenotypes lacked the preoral chamber. These *Dll* domains are comparable to spider *Dll* domains in the pedipalpal endites (Schoppmeier and Damen 2001), which were previously hypothesized to be involved in forming the spider’s “maxilla” (Prpic and Damen 2004; Pechmann et al. 2010). *Dll* expression in endites has been reported in various mandibulates (e.g., Panganiban et al. 1995; Williams 1998; Abzhanov and Kaufman 2000; Rogers et al. 2002; Giorgianni and Patel 2004; Jockusch et al. 2004). Among chelicerates, *Dll* expression has also been reported in the pedipalpal endites of the mite (thought to form the subcapitulum [the inferior part of the gnathosoma], the rutellum [a limb-like projection], and/or the corniculus [a typically horn-like process]; Evans 1992; Thomas and Telford 1999), and in the pedipalpal and all leg endites of horseshoe crabs (Mittmann and Scholtz 2001). Schoppmeier and Damen (2001) illustrated images of severe phenotypes in spider Dll RNAi embryos, which seem to show the loss of the pedipalpal endites (Figs. 4B, 5B in Schoppmeier and Damen 2001), but the focus of the authors was on the distal parts of the limbs. Similarly, in RNAi experiments with the mite Tetranychus urticae, Khila and Grbic (2007) observed reduction of the pedipalpal lobes (endites) in a particular class of Dll phenotypes, in which the limbs were truncated and antibody staining confirmed effective Dll knockdown. Our data, in conjunction with those of Schoppmeier and Damen (2001) and Khila and Grbic (2007), further support the hypothesis that Dll is involved in the growth of chelicerate pedipalpal endites (previously discussed by Prpic and Damen 2004 and Pechmann et al. 2010). These data also suggest that the spider “maxilla” and possibly the mite subcapitulum (and its projections, the rutellum and corniculus) are both homologous to the anterior part of the preoral chamber of harvestmen and scorpions. As with the gnathobases of the last pair of walking legs in the horseshoe crab (Manton 1977; Wyse and Dwyer 1973), all of these structures are involved in feeding. It is therefore tempting to reconstruct an evolutionary history of chelicerates that is characterized by progressive reduction in the number of outgrown endites, with mouthparts becoming increasingly specialized (e.g., suctorial and piercing mouthparts of derived arachnids). However, paleontological data disfavor a progressive reduction in endite number across the chelicerate tree (Weygoldt, 1998). Moreover, the placement of several orders, both extinct and extant, in chelicerate phylogeny is not definitive (Shultz, 2007; Dunlop 2010; Dunlop et al. 2012; Giribet and Edgecombe 2012). Further study is therefore required both for understanding how endites are formed in the mouthparts of the various arachnid orders and for inferring character evolution of the mouthparts based on a resolved arachnid phylogeny. Dll is required for the growth of the ocularium in the harvestman We previously postulated that pronounced *Dll* domains in parts of the eye fields (the semilunar lobes) of the harvestman could be involved in patterning the ocularium (Sharma et al. 2012b). However, this hypothesis was speculative, given that *Dll* domains occur in head lobes of other chelicerates that do not form eye mounds, where these domains are often associated with sensory structures (Thomas and Telford 2000; Abzhanov and Kaufman 2000; Mittmann and Scholtz 2001; Schoppmeier and Damen 2001). Here we observed that in *P. opilio* *Dll* RNAi embryos that developed to the normal hatching time, the ocularium was completely absent, with the eyes developing flatly on the prosomal carapace. We presently do not have the toolkit to investigate neurogenetic defects resulting from knockdown of *Dll*, as little is known about harvestman neurogenesis. However, future studies should investigate the role of *Dll* in chelicerate neurogenesis, given that *Dll* has been previously implicated in patterning chelicerate sensory structures and *Dll* domains have been reported in the head lobes of every chelicerate order studied (Mittmann and Scholtz 2001; Schoppmeier and Damen 2001; Khila and Grbic 2007). The involvement of *Dll* in forming the ocularium demonstrates another case of cooption of leg gap genes to form non-appendage outgrowths, exemplified by the sexually dimorphic horns of onthophagine beetles (Moczek and Nagy 2005; Moczek et al. 2006; Moczek and Rose 2009). Among harvestmen, the ocularium is sexually dimorphic in some species and of highly variable morphology in multiple unrelated harvestman families (Giribet et al. 2010; Sharma and Giribet 2011). The genetic basis for the sexual dimorphism is unknown, and we are presently unable to investigate it further here, because the structure is not sexually dimorphic in *P. opilio*. **Dll in the labrum** As mentioned previously, the nature of the labrum is controversial (Popadić et al. 1998; Budd 2002; Kimm and Prpic 2006; reviewed by Scholtz and Edgecombe 2006; Posnien et al. 2009). Consistent with data reported in other chelicerates (Thomas and Telford 1999; Abzhanov and Kaufman 2000; Schoppmeier and Damen 2001; Pechmann and Prpic 2009; Khila and Grbic 2007), the labrum of *P. opilio* strongly expresses *Dll* and *Dll* RNAi embryos lack the labrum. However, *Dll* (as well as other leg gap genes) is also involved in the development of non-appendage derived structures, (e.g., bristles and sensory structures; Sunkel and Whittle 1987; Cohen and Jürgens 1989; Williams et al. 2002). Inversely, some appendage-derived structures do not express *Dll* (e.g., insect mandibles, spider book lungs), making this gene an unreliable marker for limb homology. Consequently, our data can neither support nor disfavor the homology of the labrum and arthropod limbs. **dac and the three-segmented chelicera** Wild type *P. opilio* display a three-segmented chelicera that expresses *dac* in the proximal segment, consistent with the hypothesis that the deutocerebral appendage possessed a tripartite domain structure in the last common ancestor of arthropods (Sharma et al. 2012b). Among the 16 *dac* RNAi embryos displaying pedipalp and walking leg phenotypes, a single embryo was observed with a pair of identical two-segmented chelicerae, which were morphologically similar to the chelicerae observed in such chelicerate orders as Solifugae and Pseudoscorpiones (Fig. 5G) (Sharma et al. 2012b). In this phenotype, the decreased length of the appendage and the presence of a chela are consistent with the loss of the proximal segment, wherein *dac* is strongly expressed in wild type embryos (Sharma et al. 2012b). These data, albeit limited, are consistent with our previously proposed hypothesis on the mechanism of the evolutionary transition from the three- to the two-segmented cheliceral type (Sharma et al. 2012b). The mechanism for the evolutionary transitions between cheliceral types is of great interest due to the recent discovery of a fossil synziphosurine (stem xiphosuran) with elongated, antenniform chelicerae (*Dibasterium durgae*; Briggs et al. 2012). At least four distinct segments were reported in the chelicera of this fossil chelicerate species, and the flexion of the appendage suggests numerous cheliceral articles, possibly comparable to antennules in crustacean antennae. In extant chelicerates, members of a paraphyletic group at the base of Chelicerata (e.g., sea spiders, horseshoe crabs, scorpions, and harvestmen) bear three-segmented chelicerae (called chelifores in sea spiders; four-segmented chelifores also occur in some extant species [members of the genera *Achelia*, *Ammothella*, and *Eurycyde*], and the fossil sea spider *Palaeoisopus problematicus* putatively bears five-segmented chelifores; Arango 2002), whereas the members of derived arachnid orders (e.g., Tetrapulmonata) bear two-segmented chelicerae (reviewed by Sharma et al. 2012b). This hypothesis of a reductive trend in the chelicera has been previously proposed and formally treated in phylogenetic analyses (Dunlop 1996; Wheeler and Hayashi 1998; Giribet et al. 2002; Shultz 2007). The trend has been extended to the “great appendages” of Cambrian fossil arthropods, which some authors have treated as homologous to chelicerae owing to the inclusion of chelate podomeres (Chen et al. 2004; Haug et al. 2012). However, homology of the Cambrian “great appendage” and the deutocerebral appendage of extant arthropods is controversial, as the former is alternatively interpreted to be protocerebral in origin, whereas the chelicerae of extant Chelicerata are demonstrably deutocerebral (Telford and Thomas 1998; Budd 2002; Jager et al. 2006; Brenneis et al. 2008). In addition, chelate appendages have evolved convergently several times in many extant arthropods (e.g., pedipalps of scorpions, pseudoscorpions and ricinuleids; great chelae of malacostracan crustaceans and many crustacean pereiopods; the first walking legs of dryinid wasps), disfavoring homology statements based on the chelate condition. Finally, the evidence of a reductive trend has not been conclusively demonstrated even within Early Cambrian arthropods by Chen et al. (2004) or Haug et al. (2011), insofar as these appendages have not been mapped onto a numerical (i.e., cladistic) phylogenetic tree, but rather a non- analytical hypothetical scenario of cheliceral evolution based largely on cheliceral segment number. In any case, inasmuch as developmental genetics (let alone functional studies) are not feasible in extinct Early Cambrian arthropods, neither the homology statement between appendage types nor the mechanism of reduction in these appendages can be tested. By contrast, the incidence of more than three segments in the chelifores of fossil and extant pycnogonids, the antenniform chelicera of *Dibasterium*, and the disposition of cheliceral morphology across the phylogeny of arachnids are all analytically consistent with a reductive trend in the chelicera (phylogenetic analyses of Dunlop 1996; Wheeler and Hayashi 1998; Arango 2002; Giribet et al. 2002; Shultz 2007; Briggs et al. 2012). If the portion of the chelicera basal to the chela—the distal-most pair of segments, which are articulated to form a pincer—is homologous among the chelicerates and has undergone progressive reduction, then this putative trend may explain the remarkable morphological disparity between the mandibulate antenna and the chelicera, which are both appendages of the deutocerebral segment (Telford and Thomas 1998; Brenneis et al. 2008). Consequently, the proximal cheliceral segment of such lineages as harvestmen, horseshoe crabs, and sea spiders may represent the remnant of the elongate, flexible portion of the chelicera present in stem Merostomata, such as *Dibasterium*. However, as the expression of leg gap genes in a three-segmented chelicera has only been observed in the harvestman to date, it remains to be tested whether the proximal segment(s) is consistently associated with *dac* expression in other chelicerate lineages, i.e., whether *dac* is a reliable marker for proximal segment identity in the chelicera. Although our sample size was limited (n = 16 embryos with *dac* phenotypes) due to the difficulties of obtaining large numbers of embryos during the *P. opilio* breeding season, it is nevertheless surprising that only one embryo was obtained with a cheliceral phenotype, whereas the other limbs reliably underwent deletions of one or more segments. This apparent dichotomy may be attributable to incomplete knockdowns of dac. In situ hybridizations of dac RNAi embryos with a dac probe showed that whereas dac expression in the legs was reliably disrupted or entirely inhibited by injection of dac dsRNA, expression in the chelicerae was always observed (and sometimes in the pedipalps as well; 6B, C). Correspondingly, embryos exhibiting dac phenotypes in the legs and pedipalps also formed wild type chelicerae in which the proximal segment retained dac expression, even when dac was disrupted in the other appendages (Fig. 6B). Our sample sizes for the dac experiments do not suffice to examine why dac is not easily knocked down in the chelicerae. It may be, for example, that severe dac phenotypes missing a portion of the chelicera also undergo neurogenetic defects that limit survivorship. Although we report it here and score it as a “strong” cheliceral phenotype, we are unable to rule out injection artifacts and thus cannot interpret this datum unambiguously. We note, however, that the symmetry of the phenotype (a pair of two-segmented chelicerae) disfavors the possibility of an injection artifact. Furthermore, no such teratology has been reported in any other Opiliones (Juberthie, 1964), lending support to our interpretation that loss of dac function was responsible for the loss of a cheliceral segment in our experiments. As P. opilio is a wild-caught and seasonal species, the corroboration of this result requires future experiments. The function of dac should also be investigated in other lineages with three- and four-segmented chelicerae (e.g., horseshoe crabs, pycnogonids). If our model were correct, dac will be expressed in the proximal cheliceral segments and abrogation of dac expression in such lineages would also result in the formation of a two-segmented chelicera. Investigation of the four-segmented condition of some pycnogonids’ chelicerae may also elucidate how the proximal region elongates and adds segments in these lineages. This may constitute an exciting avenue for discovery of the developmental basis of the antenniform chelicera, providing a link between the disparate deutocerebral appendages of mandibulatates and chelicerates. Acknowledgments We are indebted to Nikola-Michael Prpic for helpful advice on RNAi techniques in spiders. Discussions with Ward C. Wheeler refined some of the ideas presented. Frank W. Smith, Devin O’Brien, and Taylor Ferguson provided training and/or facilitated injecting techniques. Funding for this work was provided by an EDEN fellowship (NSF IOS- 0955517) to PPS. EES was supported by DFG fellowship SCHW 1557/1-1. This work was partially supported by NSF grant IOS- 0817678 to CGE, internal MCZ funds to GG, and internal University of Connecticut funds to ELJ. Editor Lisa Nagy and two anonymous reviewers improved an earlier version of the manuscript. References Sharma et al. Page 30 of 39 Sharma et al. Page 33 of 39 Suzuki, Y., Squires, D. C., and Riddiford, L. M. 2009. Larval leg integrity is maintained by *Cladistics* 14: 173-192. into proximal and distal domains by Homothorax and Distal-less. *Development* 126: 109– 117. **Figure legends** **Fig. 1** (A) Phylogeny of Chelicerata indicating topological placement of harvestmen and spiders, the sole chelicerate orders wherein expression domains are known for all four leg gap genes. Topology derived from Giribet et al. (2001), Shultz (2007), and Giribet and Edgecombe (2012). (B) Diagram of adult male *Phalangium opilio*, lateral view of prosoma. (C) Diagram of adult male *Phalangium opilio*, ventral view of prosoma. Coxal apophyses of the pedipalp (Cxa Pp) and first walking leg (Cxa L1) form the preoral chamber (POC). Labels in boldface text in (B) and (C) indicate structures of relevance to the present study. Ch = chelicera; Cx 1-4 = coxa 1-4; Oc = ocularium; Pp = pedipalp; lb = labrum. **Fig. 2** Percentage distribution of phenotypes upon injection of *Dll*-dsRNA (left) and *dac*-dsRNA (right); see Table S1 for numerical breakdown. Phenotypes are color coded as indicated in the legend. **Fig. 3** Expression of the *Phalangium opilio Distal-less* gene in controls and *Dll* RNAi embryos. (A) Stage 17 embryo injected with DsRed-dsRNA. *Po-Dll* is expressed in the distal parts of the chelicerae, pedipalps, and legs. Additional *Dll* domains include the labrum, the pedipalpal and L1 endites (arrowheads), and the central nervous system of the prosoma (arrowheads). (B) Stage 17 embryo injected with *Dll*-dsRNA (strong phenotype). Expression of *Po-Dll* is not observed. Note loss of the chelicerae and labrum, revealing the mouth. Pedipalpal and L1 endites form, but do not form outgrowths in later stages (arrowheads). Pedipalps and legs lack all podomeres except for the coxae. (A’-B’) Counterstaining of embryos shown in (A-B) with Hoechst 33342. Scale bars for all figures are 200 µm. L1-4: leg 1-4; other abbreviations as in Fig. 1. **Fig. 4** Distal-less RNAi disrupts formation of the ocularium and preoral chamber of *P. opilio*. (A) Hatchling injected with *DsRed*-dsRNA, in lateral view. Bracket indicates the ocularium, a dorsal outgrowth bearing the eyes. (B) Same hatchling as in (A), in ventral view, showing components of a wild type preoral chamber. Dotted lines indicate outlines of the left pedipalpal and L1 coxae. Black arrows indicate outgrown L1 endites. (C) Hatchling injected with *Dll*-dsRNA, in lateral view. Note the absence of the ocularium, with the eyes flush with the scutum. (D) Hatching injected with *Dll*-dsRNA, in ventral view. Dotted lines indicate outlines of the left pedipalpal and L1 coxae. Note absence of outgrown endites and exposed mouth. Scale bar for all figures are 200 µm. Abbreviations as in Figs. 1, 3. **Fig. 5** Expression of the *Phalangium opilio dachshund* gene in strong and weak *Dll* RNAi phenotypes. (A) Stage 17 embryo injected with *DsRed*-dsRNA showing wild type expression domains of *dac*. Brackets indicate expression domain of *Po-dac* in the proximal part of the patella in pedipalps and walking legs. (B) Stage 19+ embryo injected with *Dll*-dsRNA (strong phenotype), in ventral view. *Po-dac* is expressed in the head, in the nervous system, and in the posterior terminus. *Po-dac* is also expressed in the single remaining trochanter of the right L4 (arrowhead). Asterisks indicate non-specific staining due to cuticle deposition at the termini of the coxae, as observed in previous studies (Sharma et al. 2012a, b). (C) Stage 13 embryo injected with *Dll*-dsRNA (weak phenotype), in ventral view. In this weak phenotype, all appendages except for the right L4 are truncated to some degree, with more consistent truncations on the left side. Note the retention of the labrum and one of the chelicerae. *Po-dac* is expressed in the medial regions of appendages. (D) Same embryo as in (C), in lateral view. In truncated appendages, *Po-dac* is expressed in the distal-most part of the remaining appendage. Scale bars for all figures are 200 µm. Abbreviations as in Figs. 1, 3. **Fig. 6** Expression of the *Phalangium opilio dachshund* gene. (A) Stage 12 embryo injected with *DsRed*-dsRNA in lateral view, showing wild type expression domains of *dac* in appendages. Asterisks indicate non-specific staining due to cuticle deposition in the tips of the chelicerae. (B) Dissected stage 12 embryo injected with *dac*-dsRNA. *dac* expression is observed in the chelicera and pedipalp (arrowheads) and in part of the opisthosomal ventral ectoderm, but not in the legs. (C) Stage 18 embryo injected with *dac*-dsRNA. *dac* is expressed in the proximal segment of the chelicera (bracket) and in the eye fields, in spite of disrupted expression in the pedipalps. Scale bars for all figures are 200 µm. Ef = eye field; other abbreviations as in Figs. 1, 3. **Fig. 7** Appendage mounts of stage 20 control (A-C) and *dac*-dsRNA (D-I) injected embryos. Weak *dac* phenotypes are characterized by the reduction or loss of the patella in the pedipalp (E) and leg (F). Strong *dac* phenotypes are characterized by the loss of the patella and femur in the pedipalp (H) and leg (I). A single embryo bore a two-segmented chelicera (G), in contrast to the three-segmented chelicera observed in remaining RNAi embryos (D) and controls (A). Arrowheads denote locations of segment boundaries. Scale bars for all figures are 50 µm. Chela = union of secondary and mobile segments; Fe = femur; Mt = metatarsus; Pa = patella; Pr = proximal segment; Ta = tarsus; Ti = tibia; Tr = trochanter. **Fig. 8** Summary of RNAi phenotypes in the appendages of *P. opilio*. Top: Functional domains of *Dll* and *dac* in the walking leg. Gradient of *dac* expression in the patella indicates late stage onset of expression. Lighter shading of *Dll* in trochanter indicates retention of this segment in some embryos scored as having a strong phenotype. Note that *dac* is expressed in the trochanter, but this segment is not lost in *dac* RNAi phenotypes. Middle: Functional domains of *Dll* and *dac* in the pedipalp. These are identical to their respective domains in the walking leg. Bottom: Functional domains of *Dll* and *dac* in the chelicera. Lighter shading of *Dll* in proximal part of proximal segment indicates in retention in some embryos scored as having a strong phenotype. A possible role for dac function in the chelicera is discussed in the text. Px = proximal segment; Sa = secondary article; Da = distal article. Fig. S1 Detail of ventral prosomal complex of Dll-dsRNA injected embryos. (A) Strong phenotype with retention of coxae only (dotted lines). Note absence of coxal apophyses and exposure of the oral cavity (M). (B) Strong phenotype with retention of coxae (dotted lines) and trochanters (brackets for two legs on the right side of the embryo). Note retention of basal-most part of chelicerae, absence of coxal apophyses, and exposure of the oral cavity. Scale bars for all figures are 200 µm Fig. S2 First walking leg (L1) mounts of stage 20 control (A) and dac dsRNA (B, C) injected embryos. Arrowheads denote locations of segmental boundaries. Table S1 Raw data of distribution of phenotypes upon injection of Dll-dsRNA and dac-dsRNA. Sharma et al., Figure 4 **DsRed-dsRNA (Control)** **DII-dsRNA** (A) Image showing the control group with DsRed-dsRNA. (B) Image showing the experimental group with DII-dsRNA, highlighting the L1 and Pp regions. (C) Close-up of the control group highlighting the L1 region. (D) Close-up of the experimental group, showing the L1 and Pp regions. Scale bars are present in all images. Sharma et al., Figure 5 DsRed-dsRNA (Control) DII-dsRNA A S17 B S19+ C S13 D S13 A' S17 B' S19+ C' S13 D' S13 L1 L2 L3 L4 Pp Ch Ia dac dac dac dac A' L1 L2 L3 L4 Pp Ch Ia B' Pp L1 L2 L3 L4 Ch Ia C' Pp L1 L2 L3 L4 Ch Ia D' Ch L1 L3 L4 Ia Pp L2 S17 S19+ S13 S13 Sharma et al., Figure 6 **A** and **A′**: Images of embryos treated with DsRed-dsRNA (Control). **B** and **B′**: Images of embryos treated with dac-dsRNA. **C** and **C′**: Additional images showing specific regions labeled with arrows and asterisks. Sharma et al., Figure 8 LEG PEDIPALP CHELICERA CX Tr Fe Pa Ti Mt Ta dac DII CX Tr Fe Pa Ti Ta dac DII dac? Da Px Sa DII Sharma et al., Figure S2 **DsRed-dsRNA Control** **dac-dsRNA Weak phenotype** **dac-dsRNA Strong phenotype** Table S1 <table> <thead> <tr> <th></th> <th>Normal</th> <th>Dead</th> <th>Strong phen.</th> <th>Weak phen.</th> <th>Non-spec.</th> <th>Total</th> </tr> </thead> <tbody> <tr> <td>Distal-less</td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td>19</td> <td>22</td> <td>0</td> <td>0</td> <td>0</td> <td>Uninjected 41</td> </tr> <tr> <td></td> <td>17</td> <td>18</td> <td>0</td> <td>0</td> <td>4</td> <td>DsRed-dsRNA 39</td> </tr> <tr> <td></td> <td>24</td> <td>72</td> <td>24</td> <td>3</td> <td>9</td> <td>Dll-dsRNA 132</td> </tr> <tr> <td>dachshund</td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td>40</td> <td>6</td> <td>0</td> <td>0</td> <td>0</td> <td>Uninjected 46</td> </tr> <tr> <td></td> <td>28</td> <td>25</td> <td>0</td> <td>0</td> <td>8</td> <td>DsRed-dsRNA 61</td> </tr> <tr> <td></td> <td>33</td> <td>67</td> <td>14</td> <td>2</td> <td>19</td> <td>dac-dsRNA 135</td> </tr> </tbody> </table>
Separate Space and Shared Space in Post-Apartheid South Africa Anthony Lemon Oxford University* Apartheid represented an ambitious but doomed attempt to remould South Africa’s human geography. Attempts to reform the system but preserve white control in the 1980s were the precursor of fundamental political and constitutional change in the early 1990s. Change in the social and economic spheres is fundamentally constrained by the apartheid heritage. This is explored here in relation to two key spatial issues: sharing the land and sharing the cities. The context and problems of sharing the land are considered, paying particular attention to local complexity and community participation. Post-apartheid policies and legislation concerning the ‘three Rs’—restitution, redistribution and reform of land tenure—are described and assessed in relation to their intended aims of social justice, the alleviation of poverty, national reconciliation and economic growth. The sharing of urban space is similarly constrained by the apartheid heritage, especially the effects of legally imposed racial segregation and racially discriminatory influx controls. Issues considered here include the extent, patterns and consequences of residential desegregation, and the influence of planning policies including land zoning and acquisition on urbanization, informal settlement and the spatial form of the post-apartheid city. The government’s response to these problems, including its Urban Development Strategy, is discussed. Keywords: Apartheid, land reform, restitution, land tenure, desegregation, urbanization, urban development. SEPARATE SPACE: APARTHEID AS (MIS)APPLIED GEOGRAPHY Apartheid represented an ambitious but doomed attempt to remould the social, political and economic geography of South Africa (Lemon, 1976, 1987; Smith, 1982). Ostensibly intended to minimize friction between peoples regarded as incompatible, apartheid was intended to provide a philosophically justifiable rationale for a system which would entrench white power and economic privilege in the core areas of the South African space economy, including commercial farming areas. It sought to create separate social and political spaces for white, black, colored (mixed-race) and Indian South Africans at three spatial scales: the micro-scale of facilities and amenities, or ‘petty apartheid’, the meso-scale of urban residential and commercial segregation, and the macro-scale of national government or ‘grand apartheid’ (Christopher, 1994). * School of Geography, Oxford University, Mansfield College, Oxford, OX1 3TF, U.K. Geography Research Forum • Vol. 18 • 1998:1-21 Practicalities dictated that the official fourfold racial classification of the population was only imposed at the meso-scale, principally through the Group Areas Acts of 1950 and 1966. ‘Petty apartheid’ normally distinguished only between whites and ‘non-whites’, whilst macro-scale apartheid created ten ‘homelands’ or bantustans for blacks but found no spatial solution for the highly urbanized Indian and colored groups. It resorted instead to the policy of ‘parallelism’ which created colored and Indian political institutions responsible for running purely domestic affairs of coloreds and Indians within the framework of ‘separate development’ (Rhoodie, 1973; Lemon, 1987:265–7). It did, however, seek to restrict the inter-provincial movement of Indians until 1975, and to exclude Indians altogether from the Orange Free State until 1985, whilst preference was given to colored over black labor in the Western Cape between 1962 and 1985. Parallelism reached its logical(?) conclusion in the 1984 constitution which created a tricameral parliament with separate houses responsible for the ‘own affairs’ of Indians, coloreds and whites. Blacks who constituted nearly three-quarters of South Africa’s population were excluded, as they were regarded as citizens of the homelands or ‘national states’, four of which—Transkei, Bophuthatswana, Venda and Ciskei—were officially ‘independent’ by 1981. The dilemma of ‘parallelism’ symbolized the larger problem of increasing economic integration and urbanization which haunted the apartheid project from the start. State attempts to reverse these processes through ‘influx control’ of blacks caused much misery but ultimately failed, leaving large numbers of ‘illegals’ in the cities and displacing much black urbanization across homeland boundaries, leading to spatially dispersed apartheid cities which pushed the poor to the periphery, forced to become ‘frontier commuters’ to distant jobs (Lemon, 1982). More than five million black ‘insiders’ retained legal rights to reside in the cities (Bekker and Humphries, 1985). In the homelands, overcrowding was increased both by population growth and forced resettlement from ‘white’ towns and farms. Remittances from migrant laborers were much more important than agriculture in sustaining families at low levels of living (Cobbett, 1987). From the 1960s onwards, however, the transition to monopoly capitalism led to the adoption of more capital-intensive production techniques using a smaller labor force of semi-skilled and skilled black workers, whilst economic stagnation from the mid-1970s also reduced demand for labor (Keenan, 1984; Pickles, 1991). In these conditions the homelands largely ceased to function as labor reserves, and became dumping grounds for surplus blacks. Forced resettlement from urban areas and from rural ‘black spots’ which contradicted the apartheid map were perhaps the most widely publicized aspects, but attempts to eliminate various forms of labor tenancy were more significant numerically, probably affecting at least 2 million people between the 1950s and the 1980s (Platzky and Walker, 1985), whilst many more black laborers on white farms fell victim to mechanization. The state attempted through industrial decentralization to change the distribution of economic activity so as to underpin its desired racial distribution of population, but even with some of the most generous incentives in the world in the 1980s its success was very limited (Wellings and Black, 1986; Maasdorp, 1990). Official modification of the apartheid spatial system characterized the ‘reform’ years in the mid- and late 1980s, in the misguided belief that the essence of the system could be preserved with a degree of acquiescence from those blacks benefiting materially from visible changes in township services and infrastructure, housing, and education (Lemon, 1995). Racially discriminatory influx control was abolished in 1986, although attempts to guide and channel black movement continued (Mabin, 1989). Industrial decentralization incentives were reformulated on less overtly political lines in 1991 (Black and Roux, 1991). Within the cities, market pressures began to undermine legally imposed residential segregation, leading to the emergence of ‘grey areas’ in some legally white neighborhoods. Legal recognition of a few ‘Free Settlement Areas’ in 1988 was accompanied by futile attempts to hold the line everywhere else (Lemon, 1991). Total repeal of Group Areas legislation soon followed in 1991. The emergence of racially mixed residential areas led to pressure for educational desegregation which received only a cautious official response in the early 1990s, when other aspects of the system were being dismantled, revealing a continuing determination to preserve white privilege (Lemon, 1994). Repeal of the Land Acts in 1991 removed restrictions on black purchase of white land, but in itself offered no radical change as little de facto redistribution is likely to occur through purely market mechanisms. Most of the legislation underpinning the apartheid spatial system (including its keystone, racial classification) had thus been dismantled prior to the formal ending of apartheid as a political system in 1994. The reincorporation of the homelands soon followed, reuniting South African political space. The critical question for political geographers is the extent to which these essentially political and legislative measures will lead to a genuine sharing of social and economic space in post-apartheid South Africa. Can a separation which was politically imposed be politically dismantled, or will the process of change merely continue that fueled by economic forces in the 1980s? In the short term the effectiveness of political action is weakened by the administrative complexities attendant upon the redrawing of the apartheid political map within a new constitutional structure (which changed again, although less fundamentally, with the replacement of the interim constitution with a permanent constitution in 1997). The functions of the four old provinces, nine homeland governments and three ‘own affairs’ houses of parliament under the tricameral system have been redistributed to nine new provinces. This has necessitated the redeployment of the personnel concerned and their integration into new structures. The provincial administration for the Northern Transvaal, for instance, must bring together the former administrations of Venda, Lebowa and Gazankulu, part of the administration of the former Transvaal province, and elements of departments of the three former ‘own affairs’ administrations responsible for matters which are now provincial responsibilities. Changes in the structures and boundaries of the local state have been even more complex, with a three-stage model of transition from the racialized structures of apartheid to pre-interim, interim and, after the coming into force of the new national constitution, final phases, all within less than five years (Cloete, 1995; Lemon, 1996a). Such administrative complexities at both provincial and local levels have inevitably hindered the implementation of redistributive and developmental policies, and in many cases even the administration of existing services has suffered. The genuine sharing of space is hindered more fundamentally by the apartheid heritage. Whereas the passage of apartheid laws was followed, often swiftly, by forceful implementation, their repeal is essentially passive and permissive, occurring in the context of socio-economic structures moulded by over four decades of apartheid and a much longer period of segregative practice hitherto. The extent to which the state can or should intervene actively to accelerate the sharing of socio-economic space is a crucial question for the new government. The possibilities and the problems are explored here in relation to two key spatial issues: sharing the land and sharing the cities. SHARING THE LAND: CONTEXT AND PROBLEMS Nowhere is the apartheid heritage more starkly seen than on the land. The former political boundaries of the homelands continue to mark the division between commercial agriculture and farming which for most of its practitioners falls far below the needs of subsistence. The contrast in land use and population density is, in the words of Nattrass (1981:99), 'almost like stepping through a time warp'. The ten former homelands accounted for some 13 percent of South Africa's land, or 16 percent of its 106 million hectares of agricultural land, but in 1991 they were home to about 45 percent of South Africa's 38 million people. Some 7-8 million blacks in former homelands—a little less that half their total population—depend to some degree on the land (Hanekom, 1997a), though most have access to less than two hectares, compared with an average white landholding of 1,570 hectares. There are also an estimated 200,000 labor tenants and 1 million farm workers on white farms, with an estimated 4.5 million dependants. The number of white farmers declined from 119,000 in the early 1950s to 60,000 in the early 1980s, as market forces encouraging concentration received legislative reinforcement (Beinart, 1994). Numbers increased to 67,000 in the late 1980s, in part because of increasing numbers of part-time farms, especially close to towns. In 1997 there were an estimated 55,000 commercial farmers, 97 percent of whom were white (de Wet, 1997). One quarter of these white farmers produce three-quarters of all marketable surpluses. The inefficiency of many white farmers has long been recognized: as long ago as 1970, the Du Plessis Commission found that the bottom third of white farmers produced only 3 percent of total output, and concluded that they should be encouraged to leave the land (South Africa, 1970). It was only in the 1980s, however, that the government began to reduce levels of support for white farmers; they still received over R4 billion in subsidies between 1980 and 1991 (Williams, 1996), but found their political influence diminishing as the government sought resources... to fund the ‘reform’ of apartheid. Farmers were simultaneously confronted with rising input costs, higher interest rates, mounting debts, worsening terms of trade in domestic markets, intense competition in export markets, and severe and extended drought (Francis and Williams, 1993). The resultant crisis has encouraged a process of agricultural restructuring which is long overdue; insolvency has forced many farmers out of business, especially in the summer grain areas of the southern Transvaal, northern Free State and parts of Natal, and the wool-producing Karoo (de Klerk, 1993). Accompanying shifts in land use (Table 1) generally represent a more efficient use of economic resources, although the shift to stock farming has reduced employment. Many farmers have stabilized their incomes by taking part-time, non-farm employment, often devolving day-to-day management to black employees and renting out some of their land. This creates the potential for the phased emergence of black farmers into independent production, probably through share tenancy, which could contribute in a small way to the wider restructuring which is needed (de Klerk, 1993). Beinart (1994) notes that the relatively high turnover of white land—some 4 percent p.a., much of it outside family transactions—is also conducive to market-led reforms. Table 1: Changes in agricultural land use since 1980 (%). <table> <thead> <tr> <th>Year</th> <th>Field crops</th> <th>Livestock</th> <th>Horticulture</th> </tr> </thead> <tbody> <tr> <td>1980</td> <td>nearly 50</td> <td>35</td> <td>15</td> </tr> <tr> <td>1990</td> <td>35</td> <td>45</td> <td>20</td> </tr> <tr> <td>Soon</td> <td>30</td> <td>45</td> <td>25</td> </tr> </tbody> </table> Source: de Klerk, 1993:375. With the passing in 1991 of the Abolition of Racially Based Land Measures Act the National Party government repealed the 1913 and 1936 Land Acts, but in terms which left property rights and social relations intact, and which continued to regulate the use and division of land in the name of conservation and commercial development. The 1992 White Paper on land reform claimed that the Act ensured equal access to land, but this meant little for the vast majority of blacks who lacked resources to purchase land on the open market. The ANC’s Reconstruction and Development Programme (RDP) aims to transfer 30 percent of land in historically white farming areas to black smallholders within five years. This is clearly not possible: in the first three years, only 900,000 hectares of private and state land has been identified for eventual transfer (Hanekom, 1997a). The RDP figure originated in a report of the World Bank (1993), where it appeared in an indicative model which was not intended to be used as a target (Williams, 1996). The Bank estimated the public costs of settling over 600,000 smallholdings on 30 percent of the land (24 million hectares) in four selected zones—periurban areas, summer grain regions, the Eastern Cape and the Western Cape wine farms—would be R3.5 billion p.a. over five years. Such a costing inevitably depends on assumptions about land prices, yields, crop prices and target incomes; it also underestimates administrative costs and fails to realize the higher costs of research, extension and technical assistance to small farms (Williams, 1996). Such World Bank approaches are also open to the objection that they constitute, without saying so, a vast resettlement project (Murray and Williams, 1994). Such a project would be open (for participants or those displaced, such as farm workers and their dependents) to all the risks identified by Cernea (1996) in his ethnography of resettlement and displacement worldwide, namely landlessness, joblessness, homelessness, economic marginalization, food insecurity, morbidity, and social disarticulation. De Wet (1994) considers seven different resettlement scenarios and concludes that all too often disruption of people’s socio-economic relationships and changes in their access to resources have left many people vulnerable and at risk of impoverishment; their coping strategies are restricted in the early years while they are finding their feet, and their problems may be accentuated by an inflexible settlement regime. Even return to lands originally occupied (see below) has its problems: ‘We should have no illusion that this is a second move—albeit a return home—and that in a sense a previously broken leg is being broken a second time in order to set it properly for recovery’ (de Wet, 1994). In the extensive academic literature on the land question in South Africa, two themes recur again and again: local complexity and community participation. Both argue against the imposition of inflexible policies from above, whether or not they constitute resettlement schemes. The importance of local variations cannot be over-emphasized: Matters of land and agricultural production are always particular and never general. (Williams, 1996:166) Restructuring needs to be informed by a sense of the complex, ambiguous and antagonistic nature of the discourses that shape rural struggles on the ground. (du Toit, 1994:378) Analysis of the potential for land reform should remain sensitive to local ecological and economic conditions and to the current strategies of both [white] farmers and the dispossessed. (Beinart 1994:389) The debate on land and agrarian policy is being concluded in an environment of great ignorance regarding what is really happening on the ground. (Levin and Weiner, 1993:36) Reforms which concentrate on national divisions between black and white while ignoring local divisions between black and black will ultimately fail. (Buckle, 1995:83) National agendas of reconstruction that are not rooted in the complexities of local geographies and histories, will be roundly rejected by millions of rural poor in the bantustans and on white-owned farms. (Crush and Jeeves, 1993, 354) Questions about land are also questions about gender relations, generational differences, labor and employment, access to markets, and rural-urban interaction (Murray and Williams, 1994). People want land in South Africa, in both urban and rural areas, not only to graze livestock or to grow crops, but as a place to return to in old age or unemployment, and as a security which they can rent, sell or bequeath to their children. Land is much more than a means of production: it is variously a source of security, status and power. Buckle (1995), investigating the communities of Mgwali and Lesseyton in the eastern Cape, found that differential patterns of land tenure remained critical to societal differentiation in the absence of production, as there had been little agriculture in either community in the 1980s. Demands for land ownership were prompted by considerations often far removed from production, and the attitudes of the most needy in some respects contributed to their own marginalization. Such studies underline the need for negotiation with those on the land to avoid irreversible mistakes, and for education concerning the options and problems of entering new tenurial and social relationships. Research agendas themselves need to be truly participatory (Levin and Weiner, 1993), and policy implementation is unlikely to succeed without such involvement. This is, however, far from simple. National and provincial governments are rightly keen to respond as speedily as possible to widespread demands for land, but participatory research and policy implementation require time, resources and infinite patience and sensitivity. Both local government structures and the institutions of civil society—trade unions, women’s organizations, farmers’ associations, church bodies, and other local associations—are weakly developed in rural South Africa, especially in the former homelands, where local government and civil society are complicated by the continuing importance of traditional authorities (Christiansen, 1995; Nthai, 1995). In their study of commercial smallholder development in the former KaNgwane homeland, McIntosh and Vaughan conclude that Where a wealthy class of independent farmers with similar interest to, and partly intersecting, the local and regional government authorities co-exists with a large impoverished and landless population without the resources around which to mobilize effectively, the formal trappings of democracy might not be sufficient to ensure meaningful participation in the body politic. (McIntosh and Vaughan, 1995:123–4) Such conclusions could equally apply to those who work on white-owned farms. With their families, they constitute just under one-third of South Africa’s rural population, yet they have so far been ‘oddly peripheral to the current land debate’ (du Toit 1994:375). These people too have their local practices and institutions, their localized struggles with distinctively detailed textures. South Africa's ANC-dominated government has adopted a land reform policy which is intended to redress the injustices of apartheid, foster national reconciliation and stability, underpin economic growth, and alleviate poverty (Hanekom, 1997b). It has three main components: restitution, land tenure reform and redistribution, each of which will now be briefly reviewed, together with measures affecting the welfare of farm workers. The de Klerk government made a very tentative start on restitution in 1991 by establishing an Advisory Committee on Land Allocation whose job was to identify state land for restoration to victims of forced removals. In 1993 it proposed to give the committee powers rather than simply to advise the government. The new government has gone much further by passing the Restitution of Land Rights Act in 1994 and appointing both a Land Commission and a Land Claims Court in 1995. Claims are restricted to compensation (in land or money) for acts of dispossession since the passing of the Native Land Act in 1913, and all claims have to be submitted by the 30 April 1998.4 The inability of the majority of the population to furnish written evidence makes this option feasible for only a small part of the population in practice (Hanekom, 1997b), but some 17,000 claims had been registered by August 1997. Claims go first to the Commission and then to the Court for approval of agreements or, if necessary, adjudication. Progress is painfully slow, and by August 1997 only one claim had been fully processed, and fifteen placed before the Court (Business Day, 1997a). To speed up this cumbersome procedure the Land Restitution and Reform Laws Amendment Bill (1997) provides a means of circumventing the Court where agreement is reached, or, in certain cases, for claimants to bypass the Commission and take claims directly to the Court. Both restitution and redistribution are expensive for the state, because compensation must be paid either to claimants or to whites whose land is expropriated. The constitution allows expropriation only for public purposes or in the public interest, provided that legally approved compensation is paid. The ANC argues that this need not equal the full market value if the land was acquired very cheaply from the state, whilst the Pan Africanist Congress argues that compensation should only be payable for improvements made (Kotze and Basson, 1994). White farmers not surprisingly demand the full market value of their land. Levin and Weiner (1994) regard the constitutional position as unduly favorable to white property rights rather than the rights of those who have suffered under colonialism and apartheid. The government has, however, made it clear that it does not intend to follow the current example of President Mugabe in Zimbabwe. To do so would undermine both the spirit of national reconciliation which President Mandela has tried so hard to forge, and the foreign investment which his government is working so hard to attract. As mentioned earlier, the ANC's initial approach to redistribution was directly influenced by the World Bank proposals. Accordingly, the Department of Land Affairs began by setting up pilot land reform projects and planning a land reform strategy. However, administrative and fiscal realities forced the Department to scale down the World Bank proposals dramatically. It has also been motivated by a concern to maintain public confidence in the land market, which could be undermined by policies involving large-scale expropriation of white-owned land. Instead of what amounted to an extensive resettlement program, the government's main instrument of land redistribution is the offer of individual Land Settlement/Acquisition Grants of R15,000 (equivalent to the National Housing Subsidy available in urban areas to eligible beneficiaries). This grant was subsequently increased to R17,500. The program targets labor tenants, farmworkers, women and emergent farmers. The green paper promises that by 2006, rights in land will be secured for a large proportion of those eligible (South Africa, 1996). The South African Agricultural Union, representing white farmers, has criticized the grant as inadequate to establish black farmers, arguing that the policy will lead to mass dumping grounds for rural people and expressing its concern about the loss of agricultural land (Business Day, 1996a, 1997b). The government naturally wishes to help as many people as possible, and envisages people coming together in small-scale settlement schemes which depend on the pooling of the grant to obtain land. This is indeed happening, but the hope that the grants would leverage funds from private and other sources has not materialized, which is restricting the scope of the program; the Land Bank is likely to play a critical role in achieving such leverage as it expands to serve black as well as white farmers (Duncan, 1997). There is clearly a danger that the viability of projects will be undermined if collective purchase leads to overcrowding. Restricted access to loan financing has reportedly forced people to sell livestock, an important source of income, to raise the finance for land acquisition in projects in the Natal Midlands (Business Day, 1996b). The pattern of Land Reform Projects so far approved is summarized in Table 2. The slow start in 1994 and 1995 is apparent, but what is more disturbing is the decrease in the number of approvals between 1996 and 1997, which is equally reflected in data for households affected and the area of land involved; in terms of eventual transferal, this seems likely to impact on performance in 1998 and possibly 1999 (Land Update, 1997). The 1997 figures may, however, be incomplete, as the Minister of Agriculture and Land Affairs claimed at the end of November 1997 that 380 projects had been approved to date—133 more than the overall figure in Table 2 (Hanekom, 1997b). Some 50,000 households will benefit from projects so far approved, sharing just under 500,000 hectares. Three provinces—KwaZulu-Natal, Gauteng and the Eastern Cape—account for two-thirds of all the households affected, which means that the impact of land reform is so far minimal in other provinces, with the exception of the sparsely populated Northern Cape. If problems can be surmounted and progress accelerated, the redistribution policy does have considerable merits. It avoids the pitfalls of resettlement and the inflexibility of imposed top-down policies, allowing local initiatives to succeed. It opens space for gradual acquisition, under secure forms of tenure. It targets disadvantaged Table 2: Number of land reform projects approved, designated and transferred, 1994–97. <table> <thead> <tr> <th></th> <th></th> <th></th> <th></th> <th></th> </tr> </thead> <tbody> <tr> <td></td> <td>A</td> <td>D</td> <td>T</td> <td>A</td> </tr> <tr> <td>Cape</td> <td>1</td> <td>5</td> <td>2</td> <td>13</td> </tr> <tr> <td>Free State</td> <td>-</td> <td>3</td> <td>-</td> <td>27</td> </tr> <tr> <td>Gauteng</td> <td>-</td> <td>1</td> <td>-</td> <td>15</td> </tr> <tr> <td>KwaZ/Natal</td> <td>5</td> <td>12</td> <td>5</td> <td>30</td> </tr> <tr> <td>N Cape</td> <td>-</td> <td>1</td> <td>-</td> <td>9</td> </tr> <tr> <td>Northern</td> <td>6</td> <td>1</td> <td>-</td> <td>6</td> </tr> <tr> <td>North West</td> <td>-</td> <td>5</td> <td>-</td> <td>5</td> </tr> <tr> <td>Mpumalanga</td> <td>-</td> <td>8</td> <td>1</td> <td>8</td> </tr> <tr> <td>WCape</td> <td>-</td> <td>13</td> <td>-</td> <td>23</td> </tr> <tr> <td>TOTAL</td> <td>12</td> <td>48</td> <td>8</td> <td>6</td> </tr> </tbody> </table> Terminology Approved (A) refers to the stage in the Redistribution Project Cycle when a project has been approved by the Provincial Project Approval Committee. This implies commitment of the Settlement Planning Grant (9% of the R15,000 Settlement Land Acquisition Grant). Designation (D) means that identified land has been designated for settlement by the Minister of Land Affairs. Transfer (T) means that land rights have been registered in the name of the beneficiaries of a land Reform Project. Grand total: Approved—247, Designated—110, Transferred—63. groups, although not, at the moment, those in the former homelands owing to confusion over land rights (Cross, 1997; see below). It goes some way to meeting a very widespread demand for small amounts of land: in a recent survey two-thirds of those wanting land (or more land) for farming said they wanted only 1.2 hectares or less.6 The Department of Land Affairs has adopted a ‘rights-based’ approach to land tenure reform which parallels, in its emphasis on flexibility, the redistribution policy. Its policy makes no fundamental distinction between tribal authority areas (in the former homelands) and the rest of the country, but allows for the retention of communal tenure where this is the wish of those involved.7 The new policy seeks to confirm in law whatever rights and interest in respect of land tenure people already had on the ground, including farm workers, labor tenants and women (for all of whom recognition of interest is potentially crucial). It therefore involves finding ways of transforming de facto relationships to land into formal rights. It also seeks to address the relationship between group rights and individual rights and to ensure that each is legally protected. The policy is intended to give people the right to make decisions about their own tenure system. The problem, once again, is the time taken to implement such policies community by community—twenty years has been suggested. Cross (1997) argues in relation to tribal authority areas (former homelands) that legislation has to stay minimal and flexible, meeting the needs of those near towns who tend to want more individualization as well as those in more remote areas who prefer to retain communal tenure. Informal land transactions, already widespread in tribal authority areas, need to become legal, with written security. The role of the government would essentially be one of providing the rules for economic transactions, and doing so in a way which allows intensive community participation. It is encouraging that the government is trying to improve the lot of farm workers and labor tenants. The former did not even receive the limited protection of the Basic Conditions of Employment Act or the Unemployment Insurance Act until 1992, with the former’s provisions subsequently incorporated into a new Agricultural Labor Relations Act in 1994, conferring basic rights and provision for collective bargaining. In practice extreme dependence on employers and the impracticability of collective action frequently mean that labor relations remained little changed in many areas. The new government has attempted to improve security of tenure for both farm workers and labor tenants. Correctly anticipating that the imminence of new measures could lead to evictions, the government passed the Informal Protection of Land Rights Act in 1996; in practice, however, evictions did increase substantially in the months before more permanent legislation came on to the statute book and were often carried out very harshly. Large informal settlements of sacked and evicted farm workers who are living in extreme poverty are growing around the towns in rural areas (Greenberg, 1997). Informal land rights were legally recognized in the Upgrading of Land Tenure Rights Amendment Act of 1996, as a precursor to granting formal rights. The Land Reform (Labor Tenants) Act of 1996 provided for labor tenants and their families to acquire land and security of tenure in their places of residence. Most importantly, the Extension of Security of Tenure Act of November 1997 (and in theory retrospective to February) attempts to improve tenure security for 6 million rural people. The National Land Committee, an NGO fighting for black land rights, has welcomed the Act but pointed to its conservatism in key respects (Business Day, 1997c). Overall, the government has shown both energy and resolution in relation to land tenure issues, and it may well be, when the record of these early years is examined by historians, that tenure reforms will be seen to have brought tangible benefits to more people than either the restitution or redistribution programs. SHARING THE CITIES South African cities have reflected white dominance in the social formation since colonial times. Until at least the 1950s, they shared many characteristics of other African and colonial cities (Simon, 1984). In the absence of significant indigenous urbanism, whites came to regard the cities as their cultural domain, treating blacks only as temporary sojourners whose role in the city was to provide ‘labor power without laborers’ (Maylam, 1990). Such attitudes led in the present century to controls on black migration to the cities and to segregation. Segregationist policies, embodied in the Natives (Urban Areas) Act of 1923, were in turn succeeded by the more rigid and far-reaching policy of urban apartheid, symbolized above all by the Group Areas Acts of 1950 and 1966. No other country has embarked on so thorough a reorganization of its urban space for the purposes of segregation (Lemon, 1991). The architects of apartheid did so in the realization that social relations are ‘both space forming and space contingent’ (Western, 1981), seeking through the regulation of urban space to minimize social contact and maximize white minority control of the social formation. Despite such fundamental urban restructuring, the apartheid city cannot be cut off from its roots. If many elements of earlier phases have survived the ruthless restructuring of apartheid (Christopher, 1983), who can doubt Wills’ (1991) contention that ‘the shadow of apartheid planning will be evident in the geography of the city for years to come’? The repeal of the Group Areas Act in 1991 may be compared with the repeal of the Land Acts: both are essentially passive and permissive, occurring in the context of socio-economic structures moulded over four decades of apartheid and a much longer period of segregative practice hitherto. The processes and patterns of change in post-apartheid cities offer a rich research field for urban, social and political geographers. They present the opportunity to monitor and measure the process of residential desegregation and its consequences; to assess planning policy changes including land zoning and acquisition which affect urbanization, informal settlement and the spatial form of the post-apartheid city; and to assess the degree to which changes in the provision of housing, transport and services are improving conditions for those who were formerly living under apartheid (Lemon, 1996b). This paper seeks no more than to raise some of the major questions and make brief reference to the government’s Urban Development Strategy (South Africa, 1995). Smith (1994) is almost alone in raising the issue of restitution in relation to urban land confiscation under Group Areas legislation. Such confiscation should be thoroughly recorded, making restitution considerably easier than in rural areas, but it does not appear to be on the agenda of South Africa’s first post-apartheid government. Such restitution has taken place in post-socialist Eastern Europe, but it would appear that the complexity and the cost, in view of the numbers involved, have deterred the ANC from tackling such a potentially sensitive and explosive issue. Geographers made an important and distinctive contribution to the measurement of both segregation and the beginnings of desegregation in the apartheid years (Christopher, 1989, 1990, 1991; Rule, 1988, 1989; Simon, 1989; Bernstein and McCarthy, 1990; Saff, 1990, 1991; Elder, 1990; Lemon, 1991). Perhaps surprisingly, there has been far less concern to monitor change since the removal of legislative controls. This may reflect recognition that, in the foreseeable future, residential desegregation will affect only a small minority of the population, but the signifi- cance of desegregation goes beyond numbers. Not only does it offer the chance to compare South African experience with that of other societies, but in South Africa itself desegregation is a necessary (but not sufficient) prerequisite of improved mutual tolerance, understanding and (more distantly) a degree of social integration. This is particularly important in relation to whites, who, given the demographic arithmetic and the desirability of their suburbs, will be much the most affected by desegregation. Hart (1989) argues that segregation in South African cities, freed from legal enforcement, will not disappear but will rather follow the American experience of tipping points, blockbusting and ghettoization. Experience in Harare, Windhoek and many areas in South Africa suggest otherwise, pointing to a model of (largely) peaceful co-existence. Hart’s model appears to be based very much on areas such as Hillbrow in inner-city Johannesburg, and may prove applicable to some inner areas of other South African cities. For most blacks, and many Indians and colored people, if sharing the city is to mean anything it will be the sharing of urban resources and the services they provide under the nonracial local authorities elected in 1995 and 1996. The apartheid heritage is again a constraint, given the grossly skewed distribution of resources in favor of former white areas. White fears of the consequences of sharing resources and the potential burdens of large townships and informal settlements were clearly shown in arguments over the boundaries of the new authorities, for example in Johannesburg and Cape Town (Lemon, 1996a). The whole problem of urban service provision is made more difficult by the continuing culture of non-payment which stems from the years of anti-apartheid resistance, but has now become a habit and even spread to the white population to some degree. The state’s Masakhane campaign to persuade people to pay rents and service charges has largely failed. Urbanization levels in South Africa are characterized by marked racial disparities. Indians are the most urbanized, with 88 percent living in the greater metropolitan areas, compared with 66 percent of whites, 56 percent of colored people, and 37 percent of Africans (Calitz, 1996). A further 16 percent of Africans live in other towns, though half of these are in smaller towns which might reasonably be considered part of ‘rural’ South Africa. Only 800,000 whites and coloreds, and virtually no Indians, live in truly rural areas, compared with some 16 million Africans. There is thus scope for massive further African urbanization. During the apartheid period African urbanization was not so much prevented as displaced across the borders of nearby homelands—Bophuthatswana for Pretoria, KwaZulu for Durban and Pietermaritzburg, Ciskei for East London, for example. If these homeland townships and informal settlements are included in figures for ‘functional urbanization’, the levels were increasing steadily even before the formal ending of racially discriminatory influx control in 1986. Thereafter there was some acceleration in black urbanization, and also a degree of spatial shift, with some opportunities to settle informally within black townships or on white-owned land; however many of those taking these opportunities were moving out of overcrowded township living conditions rather than migrating from rural areas (Crankshaw, 1993). The alternatives were in any case still limited, as group areas legislation still applied and the amounts of land in or close to the cities released for informal settlement were small. People were freer to move to the cities, but where were they to live? This problem has by no means disappeared in practice with the ending of apartheid, and there has been no sudden explosion of black urbanization since the political transition in 1994. However continued increase is certain, as well as continued spatial re-sorting of the black urban population now that more alternatives are open to them. Just what alternatives depends on provincial and local planning approaches. For many authorities the temptation must be to build on land already bought contiguous to former group areas and townships, and to service it inexpensively by expanding existing reticulation networks, rather than to ‘crack the racial mould’ (Pirie, 1991). The government has inherited 92,000 serviced sites based on apartheid planning, which it feels constrained to use (Business Day, 1997d). What is needed ideally is large supplies of well located, affordable land to house poor people closer to workplaces and services than in apartheid cities which relegated the poor to the periphery. This raises many questions: should planners seek to increase densities in the more affluent suburban areas, in the interest of a more compact city? Should a graduated land tax encourage such a process? Should the ‘buffer strips’ between former group areas be used for residential development? How far is it politically feasible to locate the poor adjacent to middle-class suburbs? How and where can the recreational needs of township populations be better served by the provision of parks and sports facilities? And, given that the land market is clearly going to remain essentially capitalist, what manner and degree of intervention to bring land on the market is appropriate? The Development Facilitation Act of 1995 aims to create a ‘fast track’ option for land development as an alternative to existing legislation. By reducing developers’ land holding costs the Act may also reduce land prices. In addition, by relaxing zoning regulations and allowing some mixed zoning of residential and non-residential uses, the Act aims to encourage a more compact city with higher-density suburbs. Progress towards these aims is bound to be slow, however. Distant settlements across former homeland boundaries will remain home to large numbers of people; as some manage to move closer to the city and perhaps obtain formal housing, other households are likely to take their place. The persistence of these vast settlements raises major questions about allocation of resources: how far should money be spent improving conditions for ‘South Africa’s hidden urbanites’ in sub-optimal locations such as the Winterveld, former KwaNdebele and Ciskei, and the more remote industrial growth points created by apartheid? (CDE, 1996). Similarly, the high levels of bus and rail commuter subsidy made necessary by this apartheid planning are a problem: bus subsidies amounted to R693m. in 1995–6, while the total subsidy allocated to rail commuter services in 1996–7 was R1.4 billion (SAIRR, 1997a). This is an unproductive use of resources, but the withdrawal of subsidies would be disastrous for many commuters whose long journey to work is a consequence of inherited apartheid settlement geography. The government is seeking to address inherited inequalities through subsidizing housing and service provision for the poor. Housebuilding got off to a very slow start, and by September 1997, after three and a half years, only 36.2 percent of the government’s promised million houses in five years had been built, but 673,188 household housing subsidies had been approved (SAIRR, 1997b). More than two-thirds of the state housing subsidy goes to households earning less than R1,500 per month. The provincial funding formula is also weighted in favor of rural populations by a factor of 1.25, and provisions concerning the housing subsidy of R15,000 are particularly generous for migrant laborers, allowing a choice between work location and permanent home, and, if the latter, additional subsidy for improving single quarters. Whilst the focus on those most discriminated against in the past is laudable, this effectively endorses the urbanization policies of apartheid, and may ultimately prejudice rural Africans who later wish to move permanently to the cities (Crankshaw and Parnell, 1996). South Africa currently lacks a real urbanization strategy. Its draft Urban Development Strategy (South Africa, 1996) shows a metropolitan bias, failing to realize the need to focus on the entire urban hierarchy, including secondary cities and smaller towns, using the investment made in the their schools, facilities and infrastructure; it also pays too little attention to rural-urban linkages (Lemon, 1999; CDE, 1996). It lacks investment criteria relating to resettled and displaced people, and has no clear prioritization apart from an emphasis on rebuilding the townships which receives no detailed justification. It is silent on such vital issues as urban employment creation, crime prevention, and continued non-payment of rents and service charges. It has also been strongly criticized for its marked departures from the Reconstruction and Development Programme—the omission of community organizations, women’s and other groups, lower service standards, an emphasis on cost-recovery instead of subsidization, and an excessively pro-business orientation (Bond et al., 1996). It is symptomatic of the present inadequacies of urban strategic planning that the Ministry of Housing has been entrusted with managing the Urban Development Task Team (CDE, 1996); this is likely to continue present preoccupation with such issues as housing delivery and the roles of the state and private sector in low-cost housing provision rather than the development of a true urbanization strategy (Crankshaw and Parnell, 1996). CONCLUSION If we look back to the late 1980s, before transition in eastern Europe and the Soviet Union, change in South Africa seemed inevitable but by no means round the corner. After the disaster of President P. W. Botha’s ‘Rubicon’ speech in November 1985, some white business leaders took the then remarkable step of meeting ANC leaders. They emerged with some optimism about ANC ‘moderation’ in government, but we may presume that no detailed discussions of policy took place. Let us imagine, however, that the white side had put to the ANC a program for sharing the land and sharing the cities along similar lines to those actually being pursued in 1998. There is little doubt that the ANC, even at its most diplomatic, would have rejected much of the program as too supportive of white interests, insufficiently redistributive, insufficiently interventionist and allowing too great a role for private capital. Such policies would have been condemned as falling far short of the radical restructuring and revolutionary transformation which the organization demanded. To say this is in no way to suggest that the ANC has betrayed its ideals. There is always an inevitable gap between rhetoric and reality, as the experience of ZANU-PF in Zimbabwe and SWAPO in Namibia shows only too clearly, but in the South African case the reality was changing too: the global environment, in a post-Communist era, was utterly different from that in which the ANC had conducted the liberation struggle. Its policies since coming into power clearly reflect appreciation of new global realities and their implications for aid, investment, and also for domestic relations between state and capital. Inevitably this has led to fierce criticism from radicals, though perhaps more from academics than politicians. More importantly, the limited degree to which the government has so far delivered on its promises of redistribution has inevitably caused widespread disappointment. The publication by the Department of Finance in June 1996 of its strategy for Growth, Employment and Redistribution clearly signaled a shift in emphasis from redistribution to growth. Formerly white political parties and their supporters must be relieved that their fears have not been realized, but they naturally find plenty to criticize in the policies being pursued: if they did not, there would be real cause to worry. The richness of debate is itself encouraging evidence of the strength of civil society in South Africa, and in a situation of one-party dominant democracy (Southall 1994) it is vitally important that the state shows itself responsive to the organs of civil society, sufficiently secure to recognize its errors, and prepared to modify policies in the light of experience. No one doubts the complexity and scale of South Africa’s reconstructive task. There are no easy or ideal solutions to its problems, many of which arise from the tensions implicit in trying to achieve non-material goals, such as justice and reconciliation, with limited material resources (de Wet, 1997). Current policies which seek to deal with the sharing of the land and the sharing of the cities are certainly and inevitably flawed, but they do represent a serious start to the task of improving the conditions of life for millions of people. NOTES 1. These terms, denoting officially classified ‘racial’ groups in the apartheid era, are still in widespread use in South Africa, although since the repeal of the Population Registration Act in 1991 they have no longer been used for official data collection purposes. 2. Labor tenants work part-time on white farms in return for the use of a plot of land. 3. Approximately £0.75 million in terms of the fluctuating exchange rates of the 1980s; the current rate is £1=R8. 4. It is likely that this date will be extended. Cases of unfair dispossession not addressed by the Act, including those dispossessed before 1913, are to be prioritized by the land reform program. 5. US$1=R5 approximately. 6. The survey was carried out by the Land and Agricultural Policy Center among people in tribal authority areas, townships and informal settlements and on farms. It is reported in Land Update, 44, Jan/Feb 1996, p.8. 7. Cross (1992) argues that communal tenure is a misnomer. Not only is the use of arable land individual, but in many areas this is increasingly true of ownership. The community retains a right of oversight rather than shared ownership. This effectively counters the often-used argument that communal tenure lowers productivity because it hinders individual initiative and enterprise. In his study of four Eastern Cape villages with different tenure systems, Mini (1995) actually found that far more people in Mbongweni, the village with communal tenure, were cultivating their land than in the other areas. 8. The ‘Rubicon’ speech was widely expected to announce fundamental change—the crossing of the Rubicon—but failed to do so. This led Chase Manhattan and other banks to refuse to roll over short-term loans to South Africa, and resulted in a net outflow of capital from the country in the late 1980s. REFERENCES —. (1996b) Land reform stocktaking. 27 November. —. (1997b) Settlement act creates poverty traps, says SAAU. 30 October. —. (1997c) Fears of white farmers ‘nursed for too long by ANC govt’. 26 February. —. (1997d) Urban framework to promote vision of sustainable cities. 14 November. Anthony Lemon
On The Homology Spectral Sequence For Topological Hochschild Homology Thomas J. Hunter Swarthmore College, thunter1@swarthmore.edu Follow this and additional works at: https://works.swarthmore.edu/fac-math-stat Part of the Mathematics Commons Let us know how access to these works benefits you Recommended Citation https://works.swarthmore.edu/fac-math-stat/62 This work is brought to you for free by Swarthmore College Libraries’ Works. It has been accepted for inclusion in Mathematics & Statistics Faculty Works by an authorized administrator of Works. For more information, please contact myworks@swarthmore.edu. ON THE HOMOLOGY SPECTRAL SEQUENCE FOR TOPOLOGICAL HOCHSCHILD HOMOLOGY THOMAS J. HUNTER ABSTRACT. Marcel Bökstedt has computed the homotopy type of the topological Hochschild homology of $\mathbb{Z}/p$ using his definition of topological Hochschild homology for a functor with smash product. Here we show that easy conceptual proofs of his main technical result of are possible in the context of the homotopy theory of $S$-algebras as introduced by Elmendorf, Kriz, Mandell and May. We give algebraic arguments based on naturality properties of the topological Hochschild homology spectral sequence. In the process we demonstrate the utility of the unstable "lower" notation for the Dyer-Lashof algebra. 1. Introduction The aim of this paper is to provide a first tool for calculating the homology of the topological Hochschild homology, $\text{thh}(R)$, of a commutative $S$-algebra spectrum $R$. The interest in this calculation lies in the close relation between topological Hochschild homology and algebraic $K$-theory. Throughout this paper, unless we mention otherwise, $p$ is an odd prime. Our main theorem states that in the spectral sequence calculating the mod $p$ homology of $\text{thh}(R)$ the first canonically possible differential is a certain primary operation. Here, $HZ/p$ is a cell $S$-algebra (in the sense of [5, VII]) representing reduced homology modulo $p$, and $R$ represents any $q$-cofibrant $S$-algebra. We will now state this theorem and give a brief proof. The rest of the paper will be devoted to providing the necessary definitions and proofs of statements made during this proof. The properties of the Hochschild homology spectral sequence which we shall use are enumerated in Theorem 8. In Section 7 we state how these properties are contained in [5]. Theorem 1. Let $R$ be a $q$-cofibrant $S$-algebra. Suppose $x \in (HZ/p)_n R$ with $n$ odd and positive. Then in the spectral sequence $$\text{HH}^*(HZ/p) R \Rightarrow (HZ/p)_* \text{thh}(R)$$ $\gamma^p_x [x]$ lives to $E_{p-1}$ and $$d_{p-1}(\gamma^p_x [x]) = [c\beta^{n+1} x] \gamma^p_{x-p}[x]$$ for some nonzero $c \in \mathbb{Z}/p$. Received by the editors October 14, 1994. 1991 Mathematics Subject Classification. Primary 55S12, 19D55. Here $\text{HII}_*$ denotes Hochschild homology, the square brackets are standard bar construction notation, $\gamma_{p^k}[x]$ denotes the $p^k$-th divided power of $[x]$, the $Q^i$ are Steinberger’s Dyer-Lashof operations, and the spectral sequence referred to is given by [5, IX.2.8]. Marcel Bökstedt obtained this result for $R$ a commutative functor with smash products in [1]. **Remark 2.** In Section 6 we show that the theorem also holds for odd negative $n$ given one further assumption about the Hochschild homology spectral sequence. **Remark 3.** In particular $HZ/p$ is a $q$-cofibrant $S$-algebra and given any $S$-algebra $A$ there is a weak equivalence $\Lambda A \to A$ of $S$-algebras with $\Lambda A$ $q$-cofibrant. See [5, VII] for details. Once one accepts the properties of the category of spectra our proof of this more general result is also technically simpler. In fact, the proof consists of observing the necessary naturality, identifying a universal example, and making the calculation for the universal example. **Proof.** As constructed in [5], $HZ/p \wedge_S R$ is weakly equivalent to the usual smash product. Hence, we may represent $x$ by a map $S^n \to (HZ/p) \wedge_S R$. $(HZ/p) \wedge_S (-)$ is also the left adjoint to the forgetful functor from $HZ/p$ algebras to $S$-algebras, so we can extend this to a map of $HZ/p$-algebras (that is to say $S$-algebras under $HZ/p$) $$ \begin{array}{ccc} HZ/p & \xrightarrow{=} & HZ/p \\ \downarrow & & \downarrow \\ (HZ/p) \wedge_S C(\Sigma^\infty S^n) & \xrightarrow{f} & (HZ/p) \wedge_S R \end{array} $$ by adjointness. Here $C$ is the left adjoint constructed in [5, II.4.1]. By the results of Section 2, $(HZ/p)_* f$ is a map of algebras over the Dyer-Lashof algebra which takes $\tau_n$ to $x$ and by the properties listed in Section 3 $f$ induces a map of spectral sequences. In Sections 4 and 5 the formula for $d^{p-1}$ is proved for $(HZ/p) \wedge_S C\Sigma^\infty(S^n)$. The theorem follows. **Acknowledgment.** I would like to thank Jim McClure for introducing thh to me, Frank Peterson for introducing the Adem relations to me, and everyone involved with this project for their patience. 2. **Naturality of the Dyer-Lashof Operations** We now remark that the Dyer-Lashof operations are natural transformations with the appropriate domain. Dyer-Lashof operations are defined in the homology of $H_{\infty}$-spectra in [2]. Since $S$-algebras are $E_\infty$ spectra by [5, II.4.6] and $E_\infty$ spectra are automatically $H_{\infty}$ spectra by neglect of structure, these operations are also defined in the homology of $S$-algebras. The following result is a restatement of part of McClure’s Lemma [2, IX.1.3] as it applies to his definition (in [2, IX.1]) of Dyer-Lashof operations in the homology of $H_{\infty}$ ring spectra. Let $C$ be the full subcategory of $H_{\infty}$ spectra under $HZ/p$ generated by objects of the form $(HZ/p) \wedge X$ for $X$ an $H_{\infty}$ spectrum. **Lemma 4 (McClure).** The Dyer-Lashof operations are natural operations $\pi_i \to \pi_j$ of functors from $C$ to the category of Abelian groups. We note here that with almost no extra effort, the restriction to a full subcategory in McClure's definition may be dropped yielding a definition which is both simpler and more general. In the following lemma and discussion, we freely use the notation of [2, IX.1]. **Lemma 5.** Fix a given $H_\infty$ spectrum, $E$. Given any $e \in E_m(D_pS^n)$, there is a natural transformation $Q_e : \pi_n \to \pi_m$ of functors from the category of $H_\infty$ spectra under $E$ to the category of Abelian groups. The restriction of these operations to the full subcategory $C$ of objects of the form $E \wedge X$ gives McClure's operations. **Proof.** If $e$ is represented by $g : S^m \to E \wedge D_pS^n$ and $x \in \pi_nA$ is represented by $f : S^n \to A$, we define $Q_e x$ to be represented by the following composite. $$ S^m \xrightarrow{g} E \wedge D_pS^n \xrightarrow{E \wedge D_pf} E \wedge D_p(E \wedge X) \xrightarrow{E \wedge \xi} E \wedge (E \wedge X) $$ Naturality is immediate, and agreement with McClure's definition when $A = E \wedge X$ follows from the commutativity of the following diagram which is a consequence of the definitions in [2, I]. $$ S^m \xrightarrow{g} E \wedge D_pS^n \xrightarrow{E \wedge D_pf} E \wedge D_p(E \wedge X) \xrightarrow{E \wedge \xi} E \wedge (E \wedge X) $$ Here the composite of the upper row with the right hand column is our definition and the composite of the left hand and bottom maps give McClure's. **Remark 6.** Since any $HZ/p$-algebra is an $H_\infty$ spectrum under $HZ/p$ by neglect of structure, the Dyer-Lashof operations are also natural transformations of the functors $\pi_n$ from $HZ/p$-algebras to Abelian groups. 3. **HOCHSCHILD HOMOLOGY** In this section we recall the definition of Hochschild homology and state those properties of topological Hochschild homology which we shall use in our arguments. Suppose that $C$ is a symmetric monoidal category with product $\wedge : C \times C \to C$ and unit $U \in \text{obj} C$. Write $A^k$ for the $k$-fold product $A \wedge \cdots \wedge A$ and $A^0$ for $U$. We will often abuse notation by omitting mention of the natural isomorphisms making $\wedge$ associative and unital. **Definition 7.** Let $A$ be a monoid in $(C, \wedge)$ with structure maps $\mu : A \wedge A \to A$ and $\epsilon : U \to A$. Let $M$ be a left and right (unital) $A$ module with structure maps $\mu_L : A \wedge M \to M$ and $\mu_R : M \wedge A \to M$. We define the cyclic bar construction $\text{CB}_k(A; M)$ to be the simplicial object with $k$-simplices $\text{CB}_k(A; M) = M \wedge A^k$, face maps $d_i : \text{CB}_k(A; M) \to \text{CB}_{k-1}(A; M)$, and degeneracy maps $s_i : \text{CB}_k(A; M) \to$ CB_{k+1}(A; M) defined by the following equations in which we have repeatedly suppressed mention of the identity maps for A and M. \[ d_0 = \mu_R : (M \wedge A) \wedge A^{k-1} \to M \wedge A^{k-1}, \] \[ d_i = \mu : M \wedge A^{i-1} \wedge (A \wedge A) \wedge A^{k-i-1} \to M \wedge A^{k-1} \quad (0 < i < k), \] \[ d_k = T \circ \mu_L \circ T : M \wedge A^{k-1} \wedge A \xrightarrow{\approx} A^{k-1} \wedge (A \wedge M) \to A^{k-1} \wedge M \xrightarrow{\approx} M \wedge A^{k-1}, \] \[ s_i = \epsilon : M \wedge A^i \wedge A^{k-i} \to M \wedge A^i \wedge A \wedge A^{k-i} \quad (0 \leq i \leq k). \] When C is the category of graded modules over a ring k, CB_\bullet is a simplicial graded vector space and we recover the usual Hochschild homology \( HH_\bullet(A; M) = \pi_\bullet(CB_\bullet(A; M)) \). When \( M = A \) we omit it in this and similar notation, so, for example \( HH_\bullet(A) = HH_\bullet(A; A) \). When C is the category of S-modules (or \( HZ/p \)-modules) \( CB_\bullet(A; M) \) is the simplicial S-module (or \( HZ/p \)-module) underlying the definition of thh (or thh_{HZ/p} given in [5, IX.2.1]. We now list the properties of thh which we will use to obtain our results. The proofs all are in or follow fairly quickly from [5] and are given in Section 7. Write \( \cdot \to \cdot \) for the category with two objects and one non-identity map between them and write \( A^S \) for the category of functors from B to A. Write \( E \) for the category of S-algebras constructed in [5] and \( E_{HZ/p} \) for the comma category of maps \( HZ/p \to B \). In other words, \( E_{HZ/p} \) is the category of \( HZ/p \)-algebras. Recall that for any space X equivalent to a CW-complex we have an equivalence \( C_+^X \simeq \Sigma^\infty X \). Whenever Y is a based space, we will write \( HZ/p_* Y \) as an abbreviation for \( HZ/p_* \Sigma^\infty Y \). **Theorem 8** (Elmendorf, Kriz, Mandell and May). For each object \( HZ/p \to A \to B \) in \( E_{HZ/p}^\rightarrow \), there is a spectrum \( \text{thh}_{HZ/p}(A; B) \) and a spectral sequence converging to \( \pi_* \text{thh}_{HZ/p}(A; B) \) with the following properties. We will call the spectral sequence the mod p Hochschild homology spectral sequence and we will call \( \text{thh}_{HZ/p}(A; B) \) the mod p topological Hochschild homology of A with coefficients in B. 1. \( \pi_1 \text{thh}_{HZ/p} \) and the mod p Hochschild homology spectral sequence are functors with domain the category \( E_{HZ/p}^\rightarrow \). 2. When \( A \to B \) is a map in \( E \) and A and B are q-cofibrant \( HZ/p \)-algebras, the mod p Hochschild homology spectral sequence for \( HZ/p \wedge_S A \to HZ/p \wedge_S B \) has \( E_2^{*,*} = HH_\bullet(HZ/p_* A; HZ/p_* B) \). 3. If \[ HZ/p \xrightarrow{=} \xrightarrow{=} HZ/p \] \[ \downarrow \quad \downarrow \] \[ C_1 \xrightarrow{f} \xrightarrow{=} C_2 \] \[ \downarrow \quad \downarrow \] \[ D_1 \xrightarrow{g} \xrightarrow{} D_2 \] is a map in \( E_{HZ/p}^\rightarrow \) with f and g weak equivalences and with \( C_1, D_1, C_2 \) and \( D_2 \) all q-cofibrant \( HZ/p \)-algebras, then the map induced on \( E_2 \) terms in the mod p Hochschild homology spectral sequence is an isomorphism and therefore \( \text{thh}_{HZ/p}(f; g) \) is also a weak equivalence. The mod p Hochschild homology spectral sequence is a spectral sequence of algebras. (5) Write $E_{**,}^k$ for the mod p Hochschild homology spectral sequence for the identity map on $HZ/p \wedge_S \Sigma^\infty S^n$ so we have $$E_{**,}^2 = HH_*(HZ/p_* \Sigma^\infty S^n; HZ/p_* \Sigma^\infty S^n) \Rightarrow \pi_\ast \text{thh}^{HZ/p}(HZ/p \wedge_S \Sigma^\infty S^n; HZ/p \wedge_S \Sigma^\infty S^n).$$ Let $E_{**,}^k$ be the usual bar construction spectral sequence with $$E_{**,}^2 = \text{Tor}^{HZ/p_*, QS^n}(\mathbb{Z}/p, \mathbb{Z}/p) \Rightarrow HZ/p_* QS^{n+1}.$$ Then there is an isomorphism of spectral sequences $$E_{**,}^k \cong HZ/p_* QS^n \otimes \mathbb{Z}/p \ E_{**,}^k.$$ 4. A CONVENIENT FORMULA FOR $HZ/p_* CX$ A formula for $HZ/p_* CX$ where $X$ is a unital spectrum and $C$ is Steinberger's construction [7] is given in IX.2.1 of [2]. This formula provides the necessary input to our spectral sequences because [5] shows that $C(X \vee S^0)$ is weakly equivalent to $CX$. In this section we recall this formula and introduce some notation making it easier to manipulate. We will use “lower index” notation for the Dyer-Lashof algebra in order to deal conveniently with excess and admissibility conditions. Up to a multiplicative constant this is a reindexing of the same lower notation as in [2] and in the unstable case in [4] and [9]. Rather than stabilizing the unstable formulae from the earlier references we will base all our definitions and formulae on [2]. **Definition 9.** Let $p$ be an odd prime and $x \in HZ/p_* E$ with $E$ an $E_\infty$ spectrum. For any $j \in \mathbb{Z}$ define $$Q_j x = \begin{cases} Q^{|x|+j}/2 x & \text{when } (|x| + j)/2 \text{ is an integer,} \\ Q_j x = 0 & \text{otherwise.} \end{cases}$$ The following observations are immediate from this definition and the properties listed in Theorem [2, III.1.1.7]. $(Q_j x) = p|x| + (p-1) j \equiv |x| \pmod{2}$ so $Q_j Q_k x = 0$ unless $j \equiv k \pmod{2}$ and $Q_j Q_k = 0$ unless $j \equiv k + 1 \pmod{2}$. Furthermore, $Q_j Q_k x$ is admissible for $x$ of any degree if and only if $j \leq k$ and $Q_j Q_k x$ is admissible if and only if $j \leq k - 1$. $Q_0 x = x^p$ and $Q_j x = 0$ if $j < 0$. (Note, of course, that the $Q_j$ may lower degree.) When $p$ is odd statements (3) and (4) of Theorem [2, III.1.1.7] imply the following statement about the instability of the action of the Dyer-Lashof algebra on the homology of $H_\infty$ spectra. $$Q^I x = 0 \text{ if } 2(p_1 - e_1) - |Q^I| < |x|$$ where $Q^I = \beta^e_1 Q^{i_1} \beta^e_2 Q^{i_2} \ldots \beta^e_n Q^{i_n}$. Letting $Q^I = \beta^e_1 Q^{i_1} Q^{i_2}$ we may rewrite this as the unstable condition: $Q^{i_1} Q^{i_2} x = 0$ if $2i_1 < |Q'|$ and $\beta Q^{i_1} Q^{i_2} x = 0$ if $Q^{i_1} Q^{i_2} x = (Q')^p$. Hence if $Q^I x = Q^{i_1} Q^{i_2} \ldots \beta^e_n Q^{i_n} x$ then $Q^I x$ may be nonzero only if $i_1 \geq 0$ and $\beta Q^I x$ may be nonzero only if $i_1 > 0$. (The reader may easily check that the same is true when $p = 2$ if we define $Q_j x = Q^{|x|+j} x$. Similarly, simpler versions of all our results involving the Dyer-Lashof algebra hold... when } p = 2 \text{ but we will not mention them further since our application is for odd } p. \text{ } We are now ready to restate Theorem IX.2.1 of [2]. Let } X \text{ be a unital spectrum in which the unit } \eta : \Sigma^\infty S^0 \to X \text{ is an essential map of spectra. Let } v \text{ be a generator of the image of } HZ/p. \eta. \text{ Choose } A \subset HZ/p. X \text{ so that } A \cup \{v\} \text{ is a basis for } HZ/p. X. \text{ Let } CA \text{ be the free commutative algebra generated by the set } \{QIx \mid x \in A\} \text{ where the sequence } I = (\epsilon_1, \ldots, \epsilon_n) \text{ is subject to the following conditions: } \begin{align} &n \geq 0, \\ &0 < i_1 \leq i_2 \leq \cdots \leq i_n, \\ &\epsilon_i \in \{0, 1\}, \\ &i_t \equiv \begin{cases} i_{t+1} \pmod{2} & \text{if } \epsilon_{t+1} = 0, \\ i_{t+1} + 1 \pmod{2} & \text{if } \epsilon_{t+1} = 1, \end{cases} \\ &i_n \equiv |x| \pmod{2}. \end{align} Unless explicitly stated otherwise, when we write } QIx \text{ we will assume that the above conditions hold. Write } \epsilon I = \sum_{i=1}^n \epsilon_i \text{ and } \alpha I = i_1 \text{ unless } n = 0 \text{ in which case } \alpha I = \infty. \text{ As in [2] the } E_\infty \text{ structure of } CX \text{ and the standard inclusion } X \to CX \text{ give a map } \lambda : CA \to HZ/p. CX. \text{ The following theorem is Theorem IX.2.1 of [2].} \textbf{Theorem 10 (McClure). } \lambda \text{ is an isomorphism. } 5. A counting argument for } \Sigma^\infty QS^n_+ \text{ for } n > 0 \text{ } As noted in Assumptions 8, the mod } p \text{ Hochschild homology spectral sequence for } \Sigma^\infty QS^n_+ \simeq C \Sigma^\infty S^n \text{ is just the tensor product of the constant spectral sequence } HZ/p. QS^n_+ \text{ with the usual bar construction spectral sequence } \text{Tor}^{HZ/p. QS^n_+}(\mathbb{Z}/p, \mathbb{Z}/p) \Rightarrow HZ/p. QS^n_+^{n+1}. In this section we give a simple counting argument to find the “first” differential in this spectral sequence. All our other results will follow from this one by naturality arguments. \textbf{Proposition 11. } \text{Let } n \text{ be a positive odd integer and let } i \in HZ/p. QS^n_+ \text{ be the fundamental class. In the bar construction spectral sequence } \text{Tor}^{HZ/p. QS^n_+}(\mathbb{Z}/p, \mathbb{Z}/p) \Rightarrow HZ/p. QS^n_+^{n+1} \text{ the element } [i] \ldots [i] = \gamma_p[i] \text{ lives to } E^{p-1} \text{ and } d^{p-1}\gamma_p[i] = c[\beta Q_l i] \text{ for some nonzero constant } c. \text{ Furthermore } E^2 = E^{p-1}, \text{ } E^p = E^{\infty} \text{ and } d^{p-1} \text{ is given on the algebra generators of } E^{p-1} \text{ by the formula } d^{p-1}\gamma_p[i] = c[\beta Q_l i] \gamma_{p^k-q}[Q_l i] \text{ for any odd dimensional } Q_l i \text{ satisfying the conditions (1).} \textbf{Remark 12. } A chain level argument using [6] giving this result and showing that } c \text{ can be taken to be } 1 \text{ is indicated on page 25 of [4]. Here we show that a much simpler argument may be given in the special case we are interested in and obtain the more general formula (and its extension to } THH \text{ of spectra) by naturality arguments.} \textbf{Proof. } \text{We will use the facts that this spectral sequence is a spectral sequence of Hopf algebras over the Dyer-Lashof algebra and that we know both the } E^2 \text{ term and the object to which the spectral sequence converges.} Write $P(S)$ for the polynomial algebra generated by the set $S$, $E(S)$ for the exterior algebra generated by $S$, $\Gamma(S)$ for the divided polynomial algebra generated by $S$, and $T(S)$ for the polynomial algebra uniformly truncated at height $p$ generated by $S$. Note that $|Q_I x| \equiv \epsilon I + |x| \equiv \alpha I + \epsilon_1 \pmod 2$. Using the formula from Section 4 and the fact that $n$ is odd we get the following formulae in which all congruences are modulo 2. \[(HZ/p)_*QS^n = P(Q_{I+1} \mid \epsilon I \equiv 1) \otimes E(Q_{I+1} \mid \epsilon I \equiv 0),\] \[(HZ/p)_*QS_{n+1}^n = P(Q_{I+1} \mid \epsilon I \equiv 0) \otimes E(Q_{I+1} \mid \epsilon I \equiv 1),\] \[\text{Tor}((HZ/p)_*QS^n S^2 \mid \epsilon I \equiv 0) \otimes \Gamma([Q_{I+1} \mid \epsilon I \equiv 0]).\] Here we are continuing to use the assumption that the conditions (1) hold. We will use these formulae to see where the Hilbert series for the $E^2$ term and the $E^\infty$ term first differ. First, we factor the Hilbert series of each of the terms on the right hand side of equation (2). We factor the exterior term by distinguishing generators by whether or not $\alpha I = 1$. \[h(E([Q_{I+1} \mid \epsilon I \equiv 1]) = h(E([Q_{I+1} \mid \epsilon I \equiv 1, \alpha I > 1]) \cdot h(E([\beta Q_{I+1} \mid \epsilon I \equiv 0, \alpha I > 0))\] We factor the divided power term by using $h(\Gamma(a)) = h(T(a))h(\Gamma(p(a)))$ and distinguishing truncated polynomial generators by the number of 1's in $I$. \[h(\Gamma([Q_{I+1} \mid \epsilon I \equiv 0]) = h(T([Q_{I+1} \mid \epsilon I \equiv 0, \alpha I > 1, i \geq 0]) \cdot h(\Gamma(p|Q_{I+1} \mid \epsilon I \equiv 0, \alpha I > 0))\] From the equality of total degrees $|[Q_{I+1}]| = |Q_{I-\epsilon + I+1}|$ we deduce $|[Q_{I+1}]] = |Q_{I-\epsilon + I+1}|$ when $I = (\epsilon, i_1, \ldots, \epsilon, i_n)$ and $I-1 = (\epsilon, i_1 - 1, \ldots, \epsilon, i_n - 1)$. Furthermore, if $|y| \equiv |x| + 1 \pmod 2$ then $Q_{I-\epsilon + 1}y$ satisfies the conditions (1) if and only if $Q_I x$ satisfies (1) and $\alpha I > 1$. These observations allow us to identify some of the factors as follows. \[h(E([Q_{I+1} \mid \epsilon I \equiv 1, \alpha I > 1]) = h(E(Q_{I+1} \mid \epsilon I \equiv 1)) \cdot h(T([Q_{I+1} \mid \epsilon I \equiv 0, \alpha I > 1, i \geq 0]) \cdot \prod_{i \geq 0} h(T((Q_{I+1})^{b^i} \mid \epsilon I \equiv 0, \alpha I > 0))\] Substituting, we get \[h(\text{Tor}((HZ/p)_*QS^n S^2 \mid \epsilon I \equiv 0) = h((HZ/p)_*QS_{n+1}^n) \cdot h(E([\beta Q_{I+1} \mid \epsilon I \equiv 0, \alpha I > 0)) \cdot h(\Gamma(p|Q_{I+1} \mid \epsilon I \equiv 0, \alpha I > 0))\] In particular, the smallest degree in which $h(\text{Tor}((HZ/p)_*QS^n S^2 \mid \epsilon I \equiv 0)$ differs from $h((HZ/p)_*QS_{n+1}^n)$ is $|[\beta Q_{I+1}]| = p(n+1) - 1$. We deduce there are $r_0$, $s_0$, and $t_0$ such that $s_0 + t_0 = p(n+1)$, $d^r_{s_0,t_0}$ is nonzero, and $d^s_{s,t} = 0$ for any $(r, s, t)$ with $r > 1$ and $s + t < p(n+1)$. Since $E^2_{s+t}$ is a homology spectral sequence of algebras, $d^r_{s_0,t_0}$ annihilates decomposables and $s_0 > 1$. Examination of formula (2) shows that the indecomposables of filtration greater than 1 in total degree \( p(n + 1) \) are a rank one vector space generated by \( \gamma_p[t_n] \). Since there must be a differential in this degree, \( \gamma_p[t_n] \) must support it. Since \( E_{s,*}^p \) is a spectral sequence of coalgebras, \( d^s_{0,t_0} \gamma_p[t_n] \) must be primitive. \( \beta Q_1 t_n \) spans the primitives with total degree \( p(n + 1) - 1 \) so it must be in the image of \( d_{s_0,t_0} \). The formula for \( d^p-1 \gamma_p[t] \) follows. By naturality the formula for \( d^p-1 \gamma_p[x] \) follows for any \( x \) with positive odd degree. The rest of the proposition follows as in [11, 6.10] because the spectral sequence is a spectral sequence of Hopf algebras. By the splitting result in Theorem 8 the formula also holds in the mod \( p \) Hochschild homology spectral sequence for \( \mathbb{C} \Sigma^\infty S^n \) for positive \( n \). This finishes the proofs of the statements used in the proof of Theorem 1 given in Section 1. In fact, we have demonstrated the following more general fact. **Theorem 13.** Let \( A \) be an object in \( \mathcal{E}_{HZ/p} \). Suppose \( x \in \pi_n A \) with \( n \) odd and positive. Then in the spectral sequence \[ \text{HH}_*(\pi_* A) \Rightarrow \pi_* \text{th}^H_{HZ/p}(A) \] \( \gamma_p^k[x] \) lives to \( E^{p-1} \) and \[ d^{p-1}(\gamma_p^k[x]) = [c \beta Q^n \gamma_k x] \gamma_p^{k-p}[x] \] for some nonzero \( c \in \mathbb{Z}/p \). 6. Negative Dimensions More care must be taken when \( n \) is not positive. In general there is no canonically defined coproduct—even in the universal examples—and there may be no bottom dimensional elements. For example the elements \((Q_n)^i t_n \) with \( i \geq 0 \) provide infinitely many elements of degree \( n \) in \( QHZ/p \mathbb{C}S^n \) when \( n \) is not positive, so the rank of the module of indecomposables of the same bidegree as \( \gamma_p[t_n] \) is certainly not one. In this section we note that if there is an appropriate internal action of the Dyer-Lashof algebra on the mod \( p \) Hochschild homology spectral sequence, we can use the Adem relations and this action of the Dyer-Lashof algebra to avoid these difficulties. In [8] Ligaard and Madsen provide an internal action of the Dyer-Lashof algebra in the mod 2 homology bar construction spectral sequence for the homology of the de-looping of an infinite loop space. It is reasonable to hope that similar techniques provide a vertical action in the mod \( p \) Hochschild homology spectral sequence. **Assumption 14.** The columns \( E^r_{s,*} \) in the mod \( p \) Hochschild homology spectral sequence are modules over the Dyer-Lashof algebra. The differentials respect this module structure. The action is determined by the Cartan formula on the cyclic bar construction: \[ Q^i[x_1 | \ldots | x_s] = \sum_{i_1 + \ldots + i_s = i} [Q^i x_1 | \ldots | Q^{i_s} x_s]. \] We record the result of applying this Cartan formula to the divided power generators in the mod \( p \) Hochschild homology spectral sequence in the following corollary. Corollary 15. Let \( x \in A \) be an odd dimensional element in a graded algebra \( A \) on which the Dyer-Lashof algebra acts. Then in \( \text{CB}_*(A; A) \) we have \[ Q^i \gamma_s [x] = \sum_{i_1 + \cdots + i_s = i} [Q^{i_1} x] \cdots [Q^{i_s} x] = \sum_{s_1 j_1 + \cdots + s_t j_t = i} \gamma_{s_1} [Q^{j_1} x] \cdots \gamma_{s_t} [Q^{j_t} x], \] \[ \beta \gamma_s [x] = \sum_{0 \le i < s} (-1)^i [x] \cdots [x] \beta x [x] \cdots [x] = [\beta x] \gamma_{s-1} [x]. \] Proof. This is a straightforward application of the Cartan formula. When using lower index notation in the spectral sequence, we will use total degree to calculate the indices. Thus, for example, \( Q_j [x] = Q_j \gamma_{i+j} [x] = [Q_{i+j}^j x] = [Q_{i+j+1}^j x] \). Despite this shift in dimension inherent in the lower index notation, we will often find it convenient because the formulae for the differentials are simpler in this notation. The following lemma will enable us to extend our theorem to classes in negative dimensions. Lemma 16. If \( x \) is a nonzero element in \( \text{HH}_*(HZ/p_\ast CS^n) \) with \( x \neq 0 \) and \( N \) is an integer there is \( i > N \) with \( Q_i x \neq 0 \). Note that since \( \text{HH}_*(HZ/p_\ast CS^n) = HZ/p_\ast CS^n \otimes \text{Tor}_{s,t}^{HZ/p_\ast CS^n}(Z/p, Z/p) \) it suffices to prove the theorem for \( x \neq 0, 1 \) in \( \text{Tor}_{s,t}^{HZ/p_\ast CS^n}(Z/p, Z/p) \). Before we prove this lemma we will show how it implies Theorem 13 when \( n \) is negative. Proposition 17. Let \( A \) be an object in \( E_{HZ/p} \). Suppose \( x \in \pi_n A \) with \( n \) odd. If there are vertical operations as asserted in Assumption 14 in the spectral sequence \[ \text{HH}_*(\pi_\ast A) \Rightarrow \pi_\ast \text{th}^HZ/p(A) \] then \( \gamma_{p^k} [x] \) lives to \( E^{p-1} \) and \[ d^{p-1}(\gamma_{p^k} [x]) = [c \beta Q^{n+p-1} x] \gamma_{p^{k-p}} [x] \] for some nonzero \( c \in Z/p \). Proof. By our naturality arguments, it suffices to prove the theorem for \( x = \iota_n \in HZ/p_\ast CS^n \). We will proceed by induction on \( k \). First consider the case \( k = 1 \). If \( \gamma_{p} [\iota_n] \) did not live to \( E^{p-1} \) then for some \( j \) with \( 2 \le j < p - 1 \) we would have \( d^j \gamma_{p} [\iota_n] \neq 0 \). By Corollary 15 and Theorem 13 \( Q^i d^j \gamma_{p} [\iota_n] = \gamma_{p} [Q^i p \iota_n] = 0 \) whenever \( |Q^i p \iota_n| > 0 \). This contradicts Lemma 16 so \( \gamma_{p} [\iota_n] \) does live to \( E^{p-1} \). Now let \( d^{p-1} \gamma_{p} [\iota_n] - [\beta Q^1 \iota_n] = u \) and suppose that \( u \neq 0 \). Applying the Cartan formula we get \( Q^1 d^{p-1} \gamma_{p} [\iota_n] = d^{p-1} \gamma_{p} [Q^p \iota_n] = d^{p-1} \gamma_{p} [Q^{p-1} \iota_n] \). Applying the Adem relations (See below for a convenient form.) we get \( Q^1 [\beta Q^1 \iota_n] = [\beta Q^1 Q^{p-1} \iota_n] \). Hence Theorem 13 implies \( Q^1 u = 0 \) for all large enough \( i \), which again contradicts Lemma 16. When \( k > 1 \) the proof is essentially the same, but the applications of Corollary 15 are more complicated. If \( 2 \le j < p - 1 \) Corollary 15 and the inductive hypothesis give \( Q^i d^j \gamma_{p^k} [\iota_n] = d^j \gamma_{p^k} [Q^i p \iota_n] \). Therefore, in order to avoid a contradiction between Theorem 13 and Lemma 16, \( \gamma_{p^k}[t_n] \) must live to \( E^{p-1} \). Similarly, Corollary 15 and the inductive hypothesis also give \[ Q^i(d^{p-1} \gamma_{p^k}[t_n] - [\beta Q_1 t_n] \gamma_{p^k-p}[t_n]) = d^{p-1} \gamma_{p^k}[Q^i/p^k t_n] - \gamma_{p^k-p}[Q^i/p^k t_n]. \] Once again, in order to avoid a contradiction between Theorem 13 and Lemma 16, we deduce \( d^{p-1} \gamma_{p^k}[t_n] = [\beta Q_1 t_n] \gamma_{p^k-p}[t_n] \). This determines the formula on the algebra generators, hence the proof is finished. In order to prove our lemma, we will need to refer to the Adem relations. The Adem relations also take on a simple form in the lower notation. The reindexed Adem relations are given by the following proposition: **Proposition 18.** Whenever \( l > m \) are nonnegative elements of \( \mathbb{Z} \) congruent to the degree of \( x \) modulo 2 we have the following relations. \[ Q_lQ_mx = \sum_{t \equiv x \mod 2} (-1)^{\frac{t-l}{2}} \left( \frac{t-m}{2} - \frac{l-m}{2}, \frac{l-t}{2} \right) Q_{l-p(t-m)}Q_ix, \] \[ Q_l\beta Q_m x = \sum_{t \equiv x \mod 2} (-1)^{\frac{t-l+1}{2}} \left( \frac{t-m}{2} - \frac{l-m-1}{2}, \frac{l-t-1}{2} \right) \beta Q_{l-p(t-m)-1}Q_t x, \] \[ - \sum_{t \equiv x \mod 2} (-1)^{\frac{t-l+1}{2}} \left( \frac{t-m}{2} - \frac{l-m-1}{2} - 1, \frac{l-t-1}{2} \right) Q_{l-p(t-m)}\beta Q_t x. \] **Proof.** The reader may verify that these are literal translations of the relations in [2] III.1.1.7 and III.1.1.8. See also [3], in which a similar formula appears which, if \( p \) is odd, is applicable only when \( x \) is of even degree. It is interesting to note that the degree of \( x \) does not appear in our version of these formulae. **Proof of Lemma 16 for elements of homological degree one.** In this case we have \( x \in QHZ/p_\ast CS^n \). Order the collection of sequences \( I \) first by length \( l(I) \) and then lexicographically from the left ignoring the exponents of \( \beta \). (Except for the possibility of a leading \( \beta \), if \( Q_I \) is nonzero, the exponents of \( \beta \) can be deduced from the parities of the \( i_k \).) This gives a linear ordering of the standard basis for the elements of any degree in \( QHZ/p_\ast CS^n \). In any \( \mathbb{Z}/p \) vector space with an ordered basis we will say that \( y \) has leading term \( y_0 \) if \( x = cy_0 + y \) with \( c \) nonzero in \( \mathbb{Z}/p, y_0 \) a basis element, and \( y \) a linear combination of basis elements smaller than \( y_0 \). We will abuse this language by declaring the leading term of 0 to be less than any basis element. Notice that when \( I \) has \( i_s > i_{s+1} \) for some \( s \) applying the Adem relation for \( Q_{i_s}Q_{i_{s+1}} \) or \( Q_{i_s}\beta Q_{i_{s+1}} \) replaces \( Q_I \) with a linear combination of terms of the form \( Q_J \) with \( J \) less than \( I \). For each admissible sequence \( I = (e_1, i_1 = \alpha I, \ldots, e_t, i_t = \omega I) \) we will define an equivalence class \( f(I) \mod 2p^tI \) such that the following statements hold for any \( x \in QHZ/p_\ast CS^n \) with leading term \( Q_I t_n \). If \( i > p^{I-I} \omega I \) is an integer with \( i \equiv f(I) \mod 2p^tI \) then \( Q_I x \) has leading term \( Q_I Q_i t_n \) for some \( i' \). \( i' \) is the unique integer making \( |Q_I x| = |Q_I Q_{i'} t_n| \). If \( i < p^{I-I} \omega I \) and \( i \equiv f(I) \) then \( Q_i x \) has leading term less than or equal to \( Q_i Q_j t \). If \( i \neq Q(I) \), \( Q_i x \) has leading term less than \( Q_i Q_j t \) for every \( j \). The lemma will follow immediately for the case \( s = 1 \). Define \( f(I) \) by induction on the length of \( I \) as follows: If \( I \leq 0 \), then \( x = Q_I t_n = t_n \). In this case, let \( f(I) = n \). The claimed properties are trivial. If \( I > 0 \), let \( f(I) \) be the unique equivalence class such that \( f(I) = \alpha I + \epsilon_1 \mod(2p) \) and \( \left( \frac{f(I) - \alpha I - \epsilon_1}{p} \right) + \alpha I = f(\epsilon_2, \epsilon_3, \ldots) \mod(2pI^{-1}) \). Inspection of the Adem relations shows that any integer \( f \) such that \( f = \alpha I + \epsilon_1 \mod(2p) \) and \( f \leq \alpha I \) in the expansion \( Qf \beta I Q\alpha I \) is \( \beta I Q\alpha I Q_{I - \alpha I - \epsilon I + \alpha I} \) and for any integer \( f \) such that \( f \neq \alpha I + \epsilon_1 \mod(2p) \) or \( f < \alpha I \) the leading term in the expansion \( Qf \beta I Q\alpha I \) is less than \( \beta I Q\alpha I Q_{I - \alpha I - \epsilon I + \alpha I} \). Therefore the inductive hypothesis implies that \( f(I) \) has the stated property. \[ \square \] **Proof of Lemma 16 for elements of homological degree \( s > 1 \).** Let \( C_* \) be the chain complex underlying the cyclic bar construction, so \( C_n = CB_n(H\mathbb{Z}/p^* CS^n; \mathbb{Z}/p) \), the differential is the alternating sum of the face maps and \[ H(C_*, d) = \text{Tor}^{H\mathbb{Z}/p^* CS^n}(\mathbb{Z}/p, \mathbb{Z}/p). \] Let \[ W_\ast = E ([Q_I t_n] | [Q_I t_n] \text{ is even}) \otimes \Gamma ([Q_I t_n] | [Q_I t_n] \text{ is odd}) \subseteq C_\ast. \] Let \( Z \subset W \) be defined by the same formula as \( W \) but with the added restriction that \( \alpha I > 0 \) for each \( I \) which appears. We have already implicitly used the fact that \( W_\ast \) is a submodule of cycles in \( C_* \) whose inclusion yields an isomorphism upon passing to homology. \( W_\ast \) is visibly a sub-algebra of \( C_\ast \). That it is also closed under the action of the Dyer-Lashof algebra is a consequence of the formulae in Corollary 15. Every term \( [Q_{1t_n} t_n] \ldots [Q_{s, t_n} t_n] \) of any boundary \( y \in W_\ast \) has \( \alpha I_j = 0 \) for some \( j \). Call such a term a term with leading zeros. Now order the standard basis for \( C_s = (H\mathbb{Z}/p^* CS^n)^{\otimes s} \) lexicographically from the left. If \( x \) is a nonzero element of \( C_s \) with leading term \( [Q_{1t_n} t_n] \ldots [Q_{s, t_n} t_n] \) with \( \alpha I_j > 0 \) for each \( j \), then the proof of Lemma 16 in the case of elements of homological degree one asserts there are arbitrarily large \( i \) such that \( Q_i Q_{1t_n} t_n \) has indecomposable leading term \( Q_i Q_{1t_n} t_n \). For such an \( i \), \( Q_{i+s-1} x \) has \( [Q_{I_1} t_n] Q_{I_2} t_n] \ldots [Q_{I_s} t_n] \) as its greatest term with no leading zeros. Hence \( Q_{i+s-1} x \) is not a boundary and the theorem is proved. \[ \square \] 7. Properties of the Hochschild homology spectral sequence We have been as restrictive as possible in our definition of topological Hochschild homology in order to avoid as many technical difficulties as possible. The definition we have given is a specialization of one given in [10]. **Proof of Theorem 8.** The spectral sequence is the homotopy spectral sequence for the simplicial \( H\mathbb{Z}/p \)-module \( CB_\ast(A; B) \). Functionality is clear from this definition. statements (2) and (3) follow from the fact [5, VII.6.5, VII.6.8] that when \( A \) and \( B \) are \( q \)-cofibrant commutative \( H\mathbb{Z}/p \)-algebras \( CB_\ast(A; B) \) is proper. Statement (4) follows because \( \wedge \) is pushout in \( E \) so term by term multiplication yields a map of simplicial spectra \( CB_\ast(C, D) \wedge_{H\mathbb{Z}/p} CB_\ast(C, D) \to CB_\ast(C, D) \). The identification of \( E_2^{\ast, in statement (5) also follows from [5, VII.6.8] because \( H\mathbb{Z}/p \wedge S C^\infty S^n \) is in the collection of \( H\mathbb{Z}/p \)-modules \( \tilde{E}_{H\mathbb{Z}/p} \). To deduce the rest of statement (5), let $K = (HZ/p \wedge_S C \Sigma^\infty S^n)$ and consider the diagram \[ \begin{array}{ccc} HZ/p & \rightarrow & HZ/p \\ \downarrow & & \downarrow \\ HZ/p & \rightarrow & K \\ \downarrow & = & \downarrow \\ K & \rightarrow & K \\ \downarrow & & \downarrow \\ \end{array} \] \[\eta \rightarrow (HZ/p \wedge_S C(\Sigma^\infty *))\] where $\eta$ is induced by the constant map from $S^n$ to the point $*$. Applying the cyclic bar construction at each stage yields a sequence \[(3) \quad CB_\ast (HZ/p; K) \rightarrow CB_\ast (K; K) \rightarrow CB_\ast (K; (HZ/p \wedge_S C(S^0))).\] The usual bar construction spectral sequence mentioned in statement (5) is the homology spectral sequence for the simplicial space $B_\ast (QS^n)$ which in turn is the homotopy spectral sequence for the simplicial spectrum $HZ/p \wedge B_\ast (QS^n)$. (Here $B_\ast$ is the usual bar construction.) The weak equivalences $HZ/p \wedge \Sigma^\infty QS^n_+ \simeq HZ/p \wedge CS^n$ and $HZ/p \simeq (HZ/p \wedge_S \Sigma^\infty *)$ thus induce a level-wise weak equivalence between the third term in the sequence (3) and $HZ/p \wedge B_\ast (QS^n)$. Hence the spectral sequence for the third term in (3) is the usual bar construction spectral sequence. The first term in (3) is the constant simplicial spectrum $(HZ/p \wedge_S C(S^0))$. The first map admits a left inverse by multiplying all the terms together at each level, again using the fact that $\wedge$ is a pushout. The cogroup structure then yields a map from the center term of (3) to the (termwise) coproduct of the outer terms. This last map yields an isomorphism of spectral sequences since it is an isomorphism of $E^2$ terms. (The fact that it is an isomorphism of $E_2$ terms follows from applying the argument just given to the cyclic bar construction $CB_\ast (HZ/p_\ast QS^n_+; HZ/p_\ast QS^n_+)$ in the category of graded $Z/p$ algebras.) Since the middle term in (3) is the Hochschild homology spectral sequence referred to in statement (5) the statement follows. □ **Remark 19.** On $E^2$ terms, we get a split short exact sequence of Hopf algebras \[HZ/p_\ast QS^n_+ \rightarrow HH(HZ/p_\ast QS^n_+; HZ/p_\ast QS^n_+ \rightarrow Tor^{HZ/p_\ast QS^n_+}(Z/p, Z/p).\] In general if $H$ is a unital augmented commutative graded Hopf algebra there is a split short exact sequence of Hopf algebras \[H \rightarrow HH(H; H) \rightarrow Tor^H(Z/p, Z/p).\] However, the splitting map $Tor^H(Z/p, Z/p) \rightarrow HH(H; H)$ is not the usual inclusion. For example, if $\psi x = x \otimes 1 + y \otimes 1 + x \otimes \psi x$ where $x$ and $y$ are polynomial generators, then $\psi [x] = [x] \otimes 1 + y \otimes [y] + [y] \otimes y + 1 \otimes [x]$. Therefore the usual inclusion does not commute with the coproduct. In our case, $HZ/p_\ast QS^n_+$ is a primitively generated free commutative algebra, so we do get the usual inclusion at $E^2$. **References** DEPARTMENT OF MATHEMATICS AND STATISTICS, SWARTHMORE COLLEGE, SWARTHMORE, PENNSYLVANIA 19081 E-mail address: thunter1@swarthmore.edu
On the swimming of a flexible body in a vortex street SILAS ALBEN† School of Mathematics, Georgia Institute of Technology, Atlanta, GA 30332-0160, USA (Received 22 October 2008; revised 22 May 2009; accepted 24 May 2009) We formulate a new theoretical model for the swimming of a flexible body in a vortex street. We consider the class of periodic travelling-wave body motions, in the limit of small amplitude. We calculate the output power provided to the body by thrust forces, and the input power done against pressure forces, as functions of the aspect ratio and strength of the vortex street. We then formulate two optimization problems. In the first, we determine the body wave which provides maximum output power for fixed amplitude. We find a closed-form solution with a transition from power law to exponential decay of output power as the vortex street widens. In the second problem, we incorporate internal viscoelasticity to the swimming body and compute its contribution to the input power. We find the body wave which maximizes efficiency for a given output power. The body shape and resulting efficiency are found in closed form and simple approximate formulas are given. We find that efficiency scales as the inverse of the damping parameter. Finally, we compare our results with previous experiments and simulations. We find agreement in some aspects and disagreement in others. We give physical interpretations for agreements and disagreements in terms of the phase between the body wave and vortex street. 1. Introduction The interaction between solid bodies and vortices is a central component of many instances of locomotion in fluids. In schools of fish (Weihs 1973; Abrahams & Colgan 1987) and flocks of birds (Lissaman & Shollenberger 1970; Weimerskirch et al. 2001) individuals encounter vortical structures created by other individuals, leading to significant changes in the fluid forces they experience. The same phenomenon occurs among the multiple fins of a single swimming fish (Videler 1993; Drucker & Lauder 2001). Tuning the motion of the body in response to oncoming vorticity can lead to significant savings in the energy needed for locomotion. An inviscid model of an important two-dimensional problem was put forwards by Streitlien, Triantafyllou & Triantafyllou (1996). They considered a Joukowski airfoil heaving and pitching in the flow of an alternating (von Kármán) vortex street, which is a classical model for the wake of a body at Reynolds numbers of $O(10^2 - 10^5)$. They formulated a full numerical model, and a simpler linearized model for the limit of small airfoil motions. The numerical model represents each vortex in the street as a cluster of point vortices spread over a small area. At discrete time steps, new point vortices are released near the trailing edge of the airfoil. The strength of these vortices is set to make the flow velocity finite at the trailing edge (a version of the † Email address for correspondence: alben@math.gatech.edu Kutta condition Batchelor 1967). Then they varied heaving and pitching amplitude, frequency and phase parameters, and computed the forces on the airfoil. The analytical model began by computing the instantaneous far-field flow encountered by the airfoil. This flow is the potential flow due to the vortex street at the position of the airfoil, projected onto the centreline between the alternating rows of vortices. This model, related to a model of Wu & Chwang (1975), considers the limit in which the heaving amplitude of the body is small relative to the size and to the vertical and horizontal spacing of the vortices. Their simulations found that Froude efficiency is largest when the phase between the body and the vortices ranges from $0^\circ$ to $45^\circ$. Here $0^\circ$ means that the body reaches its maximum transverse displacement when one of the point vortices is at the same streamwise location. In other words, the zero phase brings the body as close to the point vortices as possible. Based on simulations at eight phases and at eight points in the six-dimensional parameter space, they indicated that input power and thrust are also largest for phases between $0^\circ$ and $45^\circ$. However, when the body is closest to the clusters of point vortices, the error in representing a real viscous vortex by such a cluster becomes significant. In the linearized model, they found that the optimal efficiency phase ranged from $0^\circ$ down to about $-90^\circ$ as they varied the strength of the vortex street. The same phenomenon was studied experimentally by Liao et al. (2003). They produced a von Kármán street using a steady flow past a D-shaped cylinder, and placed a rainbow trout in the wake of the flow. They found that the trout maintained its streamwise position relative to the cylinder while ‘slaloming’ in between the vortices. When a given vortex approached, the trout swam around it, moving transversely away from the vortex. This motion, which was presented as the characteristic swimming motion for the trout in the vortex street, corresponded to a range of phase differences between different points on the fish body and the vortex street. The phases ranged from $\pi/2$ at the head to near $3\pi/2$ at the tail. They also found a decrease in muscle activity during the motion, supporting the notion of an increased efficiency. This experiment indicates that an actual fish may swim with a phase relative to the vortex street which is very different from the optimal phases of Streitlien et al. (1996). In general, the trout moves transversely away from the vortices while the simulations show that a motion towards the vortices is better. A more extensive study appeared in Beal et al. (2006), which interpreted the thrust gain in terms of body-vortex interactions. Also relevant are two studies of passive body motions near vorticity: Eldredge & Pisani (2008) studied computationally the passive motion of a linked rigid body in the viscous wake of a cylinder, and Kanso & Oskouei (2008) studied the passive motion of a rigid ellipse near two oppositely signed point vortices. Here we propose a new theoretical model of a body swimming in a vortex street, different from the model studied by Streitlien et al. (1996) and amenable to analytical calculation. Analytical methods are made possible by restricting to the limit where the amplitude of body motion is small relative to the streamwise and transverse spacing of the vortex street. By considering a periodic body, we avoid free distributions of vorticity shed from the body and the complications inherent in their simulation using the Kutta condition (Shukla & Eldredge 2007; Alben & Shelley 2008). We use the Hilbert transform to obtain the power output and efficiency as approximate or exact functions of the dimensionless parameters. Like previous models of this problem, ours assumes a two-dimensional inviscid flow. Flexible body swimming in a vortex street 2. Periodic flexible body in a vortex street We consider a periodic flexible body in a periodic von Kármán vortex street. The street consists of two alternating rows of vortices (see figure 1). The top row has identical point vortices, each with circulation $\Gamma$, at the points $\{ml + id/2, m \in \mathbb{Z}\}$. The bottom row has vortices with circulation $-\Gamma$ located at the points $\{(m + 1/2)l - id/2, m \in \mathbb{Z}\}$. The spacing between neighbouring vortices in a row is then $l$, and the Figure 1. The parameters for a body swimming with amplitude $h(x,t)$ in a vortex street with width $d$, horizontal spacing between vortices $l$. A background flow velocity $Ue_x$ is assumed. An outline of subsequent sections of the paper is as follows. In §2, we derive the leading-order modification to the flow due to the swimming body, which is the same as that due to a horizontal sheet. The effect is to uniformly speed up the reverse von Kármán vortex street and to slow down the regular von Kármán street. In §3 we derive analytical formulas for the leading-order vorticity distribution and pressure jump along the body, and the resulting input and output power needed to maintain a given swimming motion. We use these formulas to find optimal swimming motions for two simple problems in §4. In the first problem, we find the travelling-wave motion which maximizes output power among motions with a fixed amplitude. This identifies a particular shape of the body which produces large thrust. The optimal shape is simply proportional to the first derivative of the pressure distribution. The output power can be found exactly, and shows a transition from a power law behaviour for narrow vortex streets to an exponential behaviour for wide vortex streets. The phase difference between the optimal shape and the vortex street varies smoothly from $0^\circ$ in the limit of zero vortex street width to $90^\circ$ (saturation) at an intermediate vortex street width. The Froude efficiency is found to be the same for all travelling-wave shapes with the same spatial and temporal frequency as the vortex street. For a reverse von Kármán street, weaker and wider vortex streets allow for higher efficiencies. Stronger and narrower streets yield higher efficiencies for the regular von Kármán street, up to a limiting vortex strength. We also consider another measure of efficiency, which is the amount of vortex street energy recovered by a foil per unit time. This efficiency turns out to be proportional to output power for travelling-wave shapes. In the second problem, we include internal damping due to Kelvin–Voigt viscoelastic behaviour. Optimal efficiency shapes are smoothed versions of the pressure profile, and efficiency shows an algebraic dependence on the damping parameter, and an exponential decay for wider vortex streets relative to the undamped efficiency. In §5 we make some comments on the body’s effect on stability of vortex streets. Finally, §6 compares our main results with those of previous experiments and simulations. width of the vortex street is \( d \). For the regular von Kármán street, \( \Gamma < 0 \), while for the reverse von Kármán street, \( \Gamma > 0 \) (positive \( \Gamma \) corresponds to counterclockwise rotation). We assume that the point vortices are superposed on a background flow with uniform speed \( U \). Such is the case when vortices are shed from a stationary body in a uniform stream, or from a body swimming at constant speed through quiescent fluid. In the latter case the background flow velocity is the negative of the body velocity, when we view the vortex street in a reference frame translating with the swimming body. In the unbounded plane, the vortex street translates with uniform velocity \( U_c e_x \) given by Saffman (1992): \[ U_c = U + (\Gamma/2l) \tanh(\pi d/l). \] (2.1) We now introduce a flexible body in the form of an infinite sheet along the midline between the two alternating rows of vortices. The sheet executes small-amplitude displacements \( h(x, t) \) transverse to the mid-line, and thus has complex position \( x + \text{i}h(x, t), |h/l| \ll 1 \). We consider first the undeflected ‘base state’ in which the infinite flexible solid sheet lies exactly along the \( x \)-axis. The condition that fluid does not penetrate the body can be satisfied by posing a vortex sheet, or equivalently a jump in tangential velocity, across the body. The strength distribution of the vortex sheet is set to cancel the vertical velocity along the body induced by the translating vortex street. We shall determine the strength of the vortex sheet in the base case, which is accurate up to \( O(|h/l|, |\partial_x h|) \) in an expansion in powers of \( |h/l| \) and \( |\partial_x h| \). We shall also show that it modifies the velocity of the vortex street uniformly to a new constant velocity \( U_c e_x \). Let us first consider the flow induced by the von Kármán street alone. At the instant when one of the vortices in the top row lies on the \( y \)-axis, the flow has the following complex velocity potential (Saffman 1992): \[ w = Uz + \frac{-\text{i}\Gamma}{2\pi} \log \left( \sin \left( \frac{\pi}{l} \left( z - \frac{\text{i}d}{2} \right) \right) \right) + \frac{\text{i}\Gamma}{2\pi} \log \left( \sin \left( \frac{\pi}{l} \left( z + \frac{l}{2} + \frac{\text{i}d}{2} \right) \right) \right). \] (2.2) The complex–conjugate velocity is \[ u - \text{i}v = \frac{dw}{dz} = U - \frac{\text{i}\Gamma}{2l} \cot \left( \frac{\pi}{l} \left( z - \frac{\text{i}d}{2} \right) \right) + \frac{\text{i}\Gamma}{2l} \cot \left( \frac{\pi}{l} \left( z + \frac{l}{2} + \frac{\text{i}d}{2} \right) \right). \] (2.3) Evaluating (2.3) at \( z = x \) and simplifying, we find that the conjugate flow velocity on the \( x \)-axis is \[ u|_{y=0} = U - \frac{\text{i}\Gamma}{l} \frac{\cosh(\pi d/l)}{\sin(2\pi x/l) - \text{i} \sinh(\pi d/l)}. \] (2.4) Separated into real and imaginary parts, (2.4) reads \[ u|_{y=0} = U - \frac{\text{i}\Gamma}{l} \frac{\sinh(\pi d/l) \cosh(\pi d/l)}{\sin^2(2\pi x/l) + \sinh^2(\pi d/l)}, \] (2.5) \[ u|_{y=0} = \frac{\text{i}\Gamma}{l} \frac{\sin(2\pi x/l) \cosh(\pi d/l)}{\sin^2(2\pi x/l) + \sinh^2(\pi d/l)}. \] (2.6) In what follows it is convenient to write \( v \) in (2.6) as a sine series: \[ u|_{y=0} = \frac{\Gamma}{l} \sum_{k=1}^{\infty} v_k \sin(2\pi k x/l). \] (2.7) It turns out that only odd-\( k \) coefficients are non-zero in (2.7). The vertical velocity induced by the vortices is cancelled by the vertical velocity \(-v\) due to the vortex sheet along the horizontal body \(\gamma(x)\), which satisfies (Batchelor 1967): \[ -v = \frac{1}{2\pi} \int_{-\infty}^{\infty} \frac{\gamma(x') \, dx'}{x - x'} = \frac{1}{2} H(\gamma). \tag{2.8} \] Here \(H\) denotes the Hilbert transform. Using the identity \[ H(e^{ikx}) = -i \text{sign}(k) e^{ikx}, \tag{2.9} \] the \(\gamma\) in (2.8) corresponding to \(v\) in (2.7) is \[ \gamma = \frac{-2\Gamma}{l} \sum_{k=1}^{\infty} v_k \cos(2\pi k x/l) = \frac{-2\Gamma}{l} \frac{\cos(2\pi x/l)\sinh(\pi d/l)}{\sin^2(2\pi x/l) + \sinh^2(\pi d/l)}. \tag{2.10} \] The last expression in (2.10) is obtained by explicitly evaluating the cosine series using the coefficients for \(v_k\) from (2.6) and (2.7) and trigonometric identities. This distribution of vorticity induces a velocity at the point vortices. This velocity is a contour integral: \[ u(x, y) - iv(x, y) = \frac{1}{2\pi i} \int_{-\infty}^{\infty} \frac{\gamma(x') \, dx'}{x + iy - x'} \tag{2.11} \] \[ = \left(-\frac{2\Gamma/l}{2\pi i}\right) \sum_{k=1}^{\infty} v_k \int_{-\infty}^{\infty} \frac{\cos(2\pi k x'/l) \, dx'}{x + iy - x'}. \tag{2.12} \] Each integral in the sum (2.12) is a standard contour integral in the residue theory of complex integration (Ahlfors 1979). The integral is evaluated using separate contours when the target point is in the upper half-plane \((y > 0)\) and when the target point is in the lower half-plane \((y < 0)\). Each contour is closed, and consists of a long segment of the real axis \((-N < x < N, N \gg 1)\) joined to a large semicircle in the upper half-plane (when \(y > 0\) in (2.12)) or lower half-plane (when \(y < 0\) in (2.12)). Taking the limit \(N \to \infty\), the result is \[ u(x, y) - iv(x, y) = \frac{\Gamma}{l} \sum_{k=1}^{\infty} v_k e^{i2\pi k(x + iy)/l}, \quad y > 0 \tag{2.13} \] \[ = -\frac{\Gamma}{l} \sum_{k=1}^{\infty} v_k e^{-i2\pi k(x + iy)/l}, \quad y < 0. \tag{2.14} \] For the upper row of vortices \(x + iy = ml + id/2, m \in \mathbb{Z}\), while for the lower row of vortices \(x + iy = (m + 1/2)l - id/2, m \in \mathbb{Z}\). The velocity induced by the vortex sheet (defined in (2.14)) is the same at all point vortices, and is \[ U_{\text{ind}} = \frac{\Gamma}{l} \sum_{k=1}^{\infty} v_k e^{-\pi kd/l}. \tag{2.15} \] $U_{\text{ind}}$ can be written as the value of an analytic function at $z = id/2$: $$U_{\text{ind}} = f(z)|_{z = id/2},$$ \hfill (2.16) $$f(z) = \frac{\Gamma}{l} \sum_{k=1}^{\infty} v_k e^{2\pi iz/l},$$ \hfill (2.17) $$= \frac{\Gamma}{l} \sum_{k=1}^{\infty} v_k (\cos(2\pi k z/l) + i \sin(2\pi k z/l)).$$ \hfill (2.18) We already have an expression for $f(z)$ restricted to the real line $z = x$. The imaginary part of $f(x)$ is given by (2.6) and (2.7), and the real part is given by (2.10). Then $f(z)$ is the unique analytic extension of $f(x)$ to its maximum domain of analyticity (Ahlfors 1979). Inserting $z$ for $x$ in $f(x)$, and evaluating the result at $z = id/2$, we obtain $$U_{\text{ind}} = \frac{\Gamma}{l} \frac{1}{\sinh(2\pi d/l)}.$$ \hfill (2.19) Since $U_{\text{ind}}$ is a constant, the infinite horizontal sheet simply adds a uniform horizontal velocity to the vortex street but does not alter its spatial structure. The sheet adds negative horizontal velocity to the regular von Kármán street and positive horizontal velocity to the reverse von Kármán street; the velocity increment has the same sign as that induced by the point vortices on each other. Thus with the speed of the vortex street given by $$U_s = U_c + U_{\text{ind}} = U + \frac{\Gamma}{2l} \tanh(\pi d/l) + \frac{\Gamma}{l} \frac{1}{\sinh(2\pi d/l)},$$ \hfill (2.20) $$= U + \frac{\Gamma}{2l} \coth(\pi d/l),$$ \hfill (2.21) we obtain a self-consistent base state for the vortex street motion about a body on the horizontal axis. The velocity of the vortex street diverges as $d/l \to 0$, because in this limit $\gamma$ in (2.10) tends to a sequence of sharp peaks of vorticity, adjacent to and opposite in sign to the point vortices in the street. The speed of a pair of oppositely signed distributions of vorticity diverges as they approach one another. As $d/l \to \infty$, the vortex street speed converges to $U_s = U + \Gamma/2l$. This is the same as the speed of the vortex street in the absence of the horizontal sheet as $d/l \to \infty$. We have so far given all flow variables as functions of $x$ and $z$, which holds only at the instant when a vortex from the top row coincides with the $y$-axis. Because the point vortices translate horizontally with speed $U_s$, the flow variables $u$, $v$ and $\gamma$ are travelling waves with $x$ changed to $x - U_s t$ in the expressions given so far (setting the temporal phase so that a vortex from the upper street crosses the $y$-axis at time $t = 0$). The unsteadiness of the flow affects the pressure, as we show in the next section. 3. Pressure force, input power and output power Given the base state in which the body lies on the horizontal axis and the vortex street translates with velocity $U_s$ given by (2.21), we now consider prescribed motions of the body and calculate the resulting thrust force per unit length on it. First, because we are interested in body motions with the same length scale as the spacing between neighbouring vortices, we assume that the motion has the same spatial period as the vortex street ($l$). We make the further simplifying assumption – in agreement with Streitlien et al. (1996) and Liao et al. (2003) – that the body motion Flexible body swimming in a vortex street is a travelling wave moving with the speed of the vortex street $U_s$. When viewed in the rest frame of the vortex street, the body thus takes a constant shape. We now make the assumption that the body executes small-amplitude motions $h(x, t)$, so that $|h| \ll l$, $|\partial_i h| \ll 1$. Then we can proceed to compute the pressure jump [p] across the body, accurate to $O(|h|/l, |\partial_i h|)$, as simply that across the undeflected sheet. This provides the leading-order term in expansions of the power output $P_{out}$ due to thrust forces on the body, and the power input $P_{in}$ due to the work done by the body against fluid pressure forces. We now compute the leading-order terms in [p], $P_{out}$ and $P_{in}$. 3.1. Pressure jump We begin by noting that for transverse body motions $h(x, t)$, the velocity induced by the point vortices at the body is given by the complex conjugate of (2.3) with $z=x+ih(x, t)$. The component of this velocity normal to the body is given by the real part of its product with the quantity $(-\partial_i h - i)/\sqrt{1 + \partial_i h^2}$. Up to $O(|h|/l, |\partial_i h|)$, the normal component is the same as $v$ in (2.6). The vortex sheet strength $\gamma$ is then computed from the first (2.8) with $x'$ changed to $x' + ih(x', t)$. The result is again (2.10) up to $O(|h|/l|)$. This $\gamma$ is then used in (2.12) to compute the velocity induced by the vortex sheet at the point vortices, with $x'$ changed to $x' + ih(x', t)$. The result is again an $O(|h|/l|)$ correction, so body movements do not alter the motion of the vortex street at $O(1)$. Thus the leading-order contribution to the vortex sheet strength on the body is $\gamma$ from (2.10). We can calculate the pressure jump across a body supporting a vortex sheet in terms of the vortex sheet strength $\gamma$. One writes the Euler equation on both sides of the sheet, and takes the difference of the tangential components of the fluid acceleration terms on the either side of the body. This is done as in Saffman (1992, p. 31). The result is $$\gamma_t + \partial_s((\mu - \tau)\gamma) = \frac{1}{\rho_f} \partial_s[p].$$ (3.1) where $s$ is arclength along the body, $\rho_f$ is the fluid density, $\tau(s, t)$ is the tangential component of the body velocity and $\mu(s, t)$ is the tangential component of the average $w(s, t)$ of the fluid velocities on the two sides of the body at $s$: $$\tau(s, t) = \text{Re}(\partial_t \zeta(s, t) \bar{s}); ~ \mu(s, t) = \text{Re}(w(s, t) \bar{s}).$$ (3.2) Here the body position is the complex-valued function $\zeta(s, t)$. The tangent vector is $$s = (1 + i\partial_s h)/\sqrt{1 + \partial_s h^2}.$$ (3.3) Thus the tangential velocity due to the vertical motion $h(x, t)$ is $\tau = \partial_t h \partial_s h / \sqrt{1 + \partial_s h^2} = O(|\partial_s h|^2)$. The average fluid velocity at the body is horizontal in the base state (where the body is horizontal), and is the expression given in (2.5), a superposition of the background flow speed $U$ plus the contribution from the point vortices: $$\mu = U + \frac{\Gamma}{l} \frac{\sinh(\pi d/l) \cosh(\pi d/l)}{\sin^2(2\pi(x - U_s t)/l) + \sinh^2(\pi d/l)}.$$ (3.4) To order $|\partial_s h|^2$ the $s$ derivatives in (3.1) are $x$ derivatives, and the equation becomes $$\partial_t \gamma + \partial_s(\mu \gamma) = \frac{1}{\rho_f} \partial_s[p].$$ (3.5) Figure 2. (a) The pressure jump profile for five values of $\frac{\pi d}{l} = 0.1, 0.5, 1, 1.5, 5$. The x-axis tick labels are the same as in (b). (b) The optimal swimming shapes $h$ for the same values of $\frac{\pi d}{l}$, given by (4.3). The instant $t = 0$ is assumed for $\gamma$ in (2.10). The time-dependent $\gamma$ is the same but with $x$ replaced by $x - U_\text{st}t$. Because $\gamma$ is a travelling wave, $$\partial_t \gamma = -U_\text{st} \partial_x \gamma.$$ \hfill (3.6) and thus the solution to $[p]$ in (3.5) is $$[p] = \rho_f (\mu - U_\text{st}) \gamma,$$ \hfill (3.7) $$= -\rho_f \frac{l^2}{l^2} \left[ \sinh(\pi d/l) \cosh(\pi d/l) - \coth(\pi d/l) \sin^2(2\pi(x - U_\text{st}t)/l) \right]$$ $$\times \left( \cos(2\pi(x - U_\text{st}t)/l) \sinh(\pi d/l) \right).$$ \hfill (3.8) We note that the pressure jump is independent of the background flow speed $U$ at leading order, unlike in previous studies of slender bodies nearly aligned with flows such as a flapping flag (Shelley, Vandenberghe & Zhang 2005; Alben & Shelley 2008). The reason is that the body is undeflected in the base state, so superposing a horizontal background flow changes the flow velocity and also the fluid pressure equally above and below the body. Hence the difference in pressures is not affected by $U$ at leading order in body deflection. In figure 2(a) we plot $[p]$ for five different values of $d/l$. When the vortices are far from the swimming sheet ($d/l$ is large), the pressure jump profile tends to a cosine function. As $d/l$ decreases, the pressure jump becomes localized as sharp peaks at the horizontal location of the point vortices, and is relatively flat between the peaks. ### 3.2. Input power Motion of the body normal to itself requires an input power per unit area $p_m$ equal to the product of velocity in the normal direction with $[p]$, the force per unit area in the normal direction against which the body works. At a fixed point on the body this is $$p_m = [p] \text{Im} (\partial_t \zeta(s, t) \bar{s}),$$ \hfill (3.9) $$= [p] \partial_s h(x, t)(1 + O(|\partial_s h|^2)).$$ \hfill (3.10) using (3.3). We integrate over the period length \(0 \leq x < l\) to obtain the input power per period length, and per unit width in the third dimension: \[ P_{in} = \int_0^l [p] \partial_x h(x, t) \, dx. \] (3.11) ### 3.3. Output power The thrust force per unit area \(f_{out}\) is given by the negative of the horizontal component of the body normal times the negative of the pressure jump: \[ f_{out} = -[p] \text{Re}(\hat{n} \cdot \hat{e}_x), \] (3.12) \[ = -[p] \partial_x h / \sqrt{1 + \partial_x h^2}, \] (3.13) \[ = -[p] \partial_x h + O(|\partial_x h|^3). \] (3.14) If we consider the problem in the frame in which the background flow is at rest, the body moves upstream at a prescribed velocity \(-Ue_x\). The work done on the body per unit time (power) per unit area in this frame by the thrust force per unit area (3.14) is \(p_{out}\), at leading order: \[ p_{out} = -U \int_0^l [p] \partial_x h(x, t) \, dx. \] (3.15) \[ P_{out} = -U \int_0^l [p] \partial_x h(x, t) \, dx. \] (3.16) \(P_{out}\) is the output power per unit period length, per unit width in the third dimension. Similar expressions for \(P_{in}\) and \(P_{out}\) were used in theoretical studies of fish swimming by Lighthill (1960) and Wu (1961). Because \([p]\) and \(h\) are both travelling waves with the same spatial and temporal period, so are the products in the integrands of \(P_{in}\) and \(P_{out}\). As time evolves, the periodic integrands simply shift within the interval \([0, l]\), so \(P_{in}\) and \(P_{out}\) are constant in time, and thus their time averages are the quantities themselves. We now consider constrained optimization problems which identify optimal swimming motions \(h(x, t)\). ### 4. Optimal motions #### 4.1. Fixed mean square amplitude We first compute the shapes which maximize power output for a given mean square amplitude. This identifies a particular body shape, independent of amplitude, for delivering large thrust. We thus maximize the functional \[ L_1 = P_{out} + \lambda \left( A^2 - \frac{1}{l} \int_0^l h(x', t)^2 \, dx' \right), \] (4.1) where \(P_{out}\) is given by (3.16) and \(A\) is the mean square amplitude. Inserting \(h \sim A\) into (3.16), and examining the form of \([p]\) (defined in (3.8)), we see that \(P_{out}/\rho_f A\) is a function of four parameters: \(\Gamma, l, U, d\). From these we form two dimensionless parameters for this problem: \(\Gamma/lU, d/l\). In the following we shall see that only the dependence on \(d/l\) is non-trivial. Taking the variation of (4.1) with respect to \(h\) and integrating by parts, \[ \delta L_1 = \int_0^l U \partial_x [p] \delta h(x', t) \, dx' - \lambda \left( \frac{1}{l} \int_0^l 2h(x', t) \delta h(x', t) \, dx' \right). \] (4.2) The phase difference is the horizontal distance between a point vortex in the upper row of vortices and the nearest peak in $h(x, t)$ downstream (see figure 2b). In figure 3 we plot the phase difference between the peak of the optimal body shape and the vortex street. We plot the phase difference in degrees, where $360^\circ$ equals one spatial period. The phase difference moves gradually from $0$ when $d/l = 0$ to $90^\circ$ when $d/l = 0.684$. Above this value of $d/l$, the two peaks of $h$ which occur in the range $0 \leq (x - U_s t)/l \leq 1/2$ in figure 2(b) have merged into a single peak at $(x - U_s t)/l = 1/4$. The value of $P_{out}$ generated by the $P_{out}$-maximizing shape (4.3) is $$P_{out} = U A l \sqrt{\frac{1}{l} \int_0^l (\partial_x [p])^2 \, dx}. \quad (4.4)$$ Because $[p]$ in (3.8) is a rational expression of trigonometric functions, so is $h$ in (4.3) and so is the integrand of the maximum output power (4.4). It is possible to compute the maximum output power in closed form using a symbolic integration package. Here we use Mathematica 6. The result is $$P_{out} = \rho f U A \frac{\Gamma^2}{l^2} \sqrt{\frac{\pi(115 + 76 \cosh(4d\pi/l) + \cosh(8d\pi/l))}{\sinh(2d\pi/l)}}. \quad (4.5)$$ In figure 4 we plot $P_{out}$ versus $d/l$. For large $d/l$, the power output decays exponentially: $$P_{out} = \rho f U A \frac{\Gamma^2}{l^2} 2\sqrt{\pi} e^{-d\pi/l} + O(e^{-2d\pi/l}), \quad \frac{d}{l} \to \infty, \quad (4.6)$$ Flexible body swimming in a vortex street While for small \(d/l\) the power out diverges like a power law, as the sheet deformation becomes localized near the point vortices: \[ P_{\text{out}} = \rho_f U A \frac{\Gamma^2}{\pi^2 l^2} \sqrt{\frac{3}{2}} \left( \frac{d}{l} \right)^{-5/2} + O \left( \left( \frac{d}{l} \right)^{-1/2} \right), \quad \frac{d}{l} \to 0. \tag{4.7} \] There is a smooth transition from one regime to the other near \(d = l\). We now consider the question of Froude efficiency. It turns out that all travelling-wave body shapes \(h(x - U_s t)\) have the same Froude efficiency, or else \(P_{\text{in}}\) and \(P_{\text{out}}\) are zero. This follows from the fact that \(\partial_t h = -U_s \partial_x h\). By the definitions of \(P_{\text{out}}\) and \(P_{\text{in}}\), \[ \eta = \frac{P_{\text{out}}}{P_{\text{in}}} = \frac{U}{U_s} = \left( 1 + \frac{\Gamma}{2lU} \coth(\pi d/l) \right)^{-1}. \tag{4.8} \] Because of the travelling-wave form of \(h\) and \([p]\), both \(P_{\text{out}}\) and \(P_{\text{in}}\) are proportional to the correlation between the slope of the body shape wave and the pressure wave. All travelling waves have the same such correlation. In figure 5 we plot contours of constant \(\eta\) in the two-parameter space of reduced vortex circulation and reduced vortex street width, for the case \(\Gamma > 0\). High efficiency... occurs with very weak vortices (small $\Gamma/lU$). Weaker vortices also result in a slower-moving vortex street. Thus the velocity of the body wave is smaller, leading to a smaller $P_{in}$. Conversely, stronger vortices require the body wave to move more quickly, which increases $P_{in}$ (by increasing $\partial_t h$) and decreases the efficiency. Efficiency increases as the vortex street becomes wider, up to a critical value of $d/l$ near 1, where the efficiency approaches a constant limiting value. Our expressions for $[p]$ and $P_{out}$ involve $\Gamma$ only as $\Gamma^2$, and thus are the same for regular and reverse von Kármán streets. Our expression for Froude efficiency (4.8) involves the first power of $\Gamma$, however, and can be greater than 1 for a regular von Kármán street ($\Gamma < 0$), while it is always less than 1 for a reverse von Kármán street ($\Gamma > 0$). When $\Gamma < 0$ Froude efficiencies greater than 1 are common (Streitlien et al. 1996), and the term ‘efficiency’ is perhaps misleading because the body does no work in setting up the vortex street, but gains output power from it. It is then useful to consider an alternative definition of efficiency, which is the amount of kinetic energy in the vortex street recovered by the body per period length, per unit time (Streitlien et al. 1996): $$\eta_1 = \frac{P_{out} - P_{in}}{U \langle D \rangle},$$ (4.9) where $\langle D \rangle$ is the time-averaged drag force on the object which sheds the vortex street. The outward momentum flux due to the point vortices leaving a control volume around the object is used to calculate $\langle D \rangle$ (Saffman 1992): $$\langle D \rangle = \frac{\Gamma^2}{2\pi l} + \frac{\Gamma d}{l} (U - 2U_c).$$ (4.10) Because the body is a travelling wave, $P_{in} = (U_s/U)P_{out}$ and $$\eta_1 = \frac{(U - U_s)P_{out}}{U^2 \langle D \rangle}.$$ (4.11) Maximizing $\eta_1$ is thus equivalent to maximizing $P_{out}$, which we have already done under the constraint of fixed amplitude. 4.2. Maximum efficiency with internal damping Thus far we have considered only the interaction of a flexible surface with an external flow due to a vortex street. We have neglected the internal work required for the body to perform a given motion. The muscles, tissues and organs of the fish body provide considerable resistance to bending (Videler 1993; Long et al. 1996), and evidence exists that the elastic properties of the fish body are tuned to hydrodynamic forces (Long et al. 1996; Wainwright 2000; Beal et al. 2006). One of the most basic ways to consider the effect of the internal resistance to bending is to model the fish as a beam with bending rigidity (Cheng, Pedley & Altringham 1998). Here we incorporate a uniform bending rigidity into our model of the flexible body, and show how the required input power and achievable efficiency is altered. For a periodic beam with uniform flexural rigidity $B$, the stored elastic energy per period length $l$ is $$E_b = \frac{B}{2} \int_0^l (\partial_{xx} h(x', t))^2 \, dx'.$$ (4.12) Because the motion $h(x, t)$ is periodic in time, $E_b$ does not change over one period. Hence bending rigidity alone does not affect the time-averaged input power. However, real elastic structures also have internal damping, which can be modelled as internal viscoelastic behaviour. One of the simplest and most widely used models for this phenomenon is the Kelvin–Voigt model, in which the stress tensor is a linear combination of the strain tensor and the rate-of-strain tensor (Banks & Inman 1991; Cheng et al. 1998). The result is a term proportional to $\partial_{xxxx}h$ in the beam equation (assuming spatially uniform damping): $$\rho \partial_{tt}h + B \partial_{xxxx}h + c \partial_{xxxx}h = f(x, t). \quad (4.13)$$ Here $\rho$ is beam mass per unit length, $c$ is the non-negative damping coefficient, and $f$ is an applied force per unit length: $$f(x, t) = -[p](x, t) + \partial_{xx}M_{\text{int}}(x, t), \quad (4.14)$$ where $[p]$ is the pressure jump (3.8) and $M_{\text{int}}$ is the internal moment which produces the prescribed motion $h(x, t)$. Specifically $M_{\text{int}}(x, t)$ is the moment that material in the interval $\{x' : x' > x\}$ applies to the material in the interval $\{x' : x' < x\}$, in the notation of standard beam theory (Segel 1977). The alternating contraction of muscle fibres on either side of the fish backbone is the source of $M_{\text{int}}$. The sum of kinetic and elastic potential energy of the beam per unit periodic length is $$W(t) = \int_0^l \left( \frac{\rho}{2} (\partial_t h(x', t))^2 + \frac{B}{2} (\partial_{xx} h(x', t))^2 \right) \, dx'. \quad (4.15)$$ The time derivative of $W$ is $$\frac{dW}{dt} = \int_0^l (\rho \partial_{tt} h(x', t) \partial_t h(x', t) + B \partial_{xxxx} h(x', t) \partial_t h(x', t)) \, dx', \quad (4.16)$$ $$= \int_0^l \left[ -c (\partial_{xx} h)^2 - [p] \partial_t h(x', t) \, dx' + \partial_{xx} M_{\text{int}}(x', t) \partial_t h(x', t) \right], \quad (4.17)$$ where we have used (4.13) and integration by parts (with periodic boundary conditions). Because the motion of the beam is periodic, the integral of $dW/dt$ over one temporal period $T$ is zero. Thus, $$\int_0^T \int_0^l \partial_{xx} M_{\text{int}}(x', t') \partial_t h(x', t') \, dx' \, dt' = \int_0^T \int_0^l c (\partial_{xx} h)^2 + [p] \partial_t h(x', t') \, dx' \, dt'. \quad (4.18)$$ The quantity on the left is the time-averaged internal power per spatial wavelength used to maintain the motion $h(x, t)$. We see that it is equal to the negative of the rate of energy dissipation in internal damping plus the time-averaged power applied against fluid pressure. We thus modify the input power in (3.11) to take internal damping into account: $$P'_{\text{in}} = \int_0^l (c (\partial_{xx} h)^2 + [p] \partial_t h(x', t')) \, dx'. \quad (4.19)$$ Equation (4.19) is equal to its time-average, because again we assume $h(x, t)$ is a travelling wave with spatial period $l$. We now maximize the efficiency $$\eta' = P_{\text{out}} / P'_{\text{in}}. \quad (4.20)$$ In the limit where the amplitude of the body wave $\max_x |h(x, t)|/l$ goes to zero, the damping term in (4.19) becomes negligible and we recover the case where all body waves with non-zero power have the same efficiency $U/U_s$. When we constrain the body wave to have a fixed positive power output, a particular body wave maximizes the efficiency $\eta'$. Thus we optimize $$L_2 = \frac{P_{\text{out}}}{P_{\text{in}}'} + \lambda \left( S - \int_0^l -U \partial_x h[p] \, \text{d}x' \right), \quad (4.21)$$ where $S$ is the fixed power output. Taking the variation of $L_2$ with respect to $h$ and integrating by parts yields the equation for $h$: $$\partial_x[p] \left( UP_{\text{in}}' - U_s P_{\text{out}} - \lambda U P_{\text{in}}'^2 \right) = -2P_{\text{out}} c U_s^2 \partial_x h. \quad (4.22)$$ We find that $h$ is proportional to the fifth antiderivative of $[p]$: $$h = c_0 D^{-5}[p], \quad (4.23)$$ where negative powers of $D$ denote antiderivatives, and $c_0$ is a constant to be determined. $D^{-5}$ is a smoothing operator which damps the amplitudes of the cosine components of $[p]$ by wavenumber to the fifth power. Because $[p]$ contains only odd-wavenumber cosines, $h$ is very well approximated by just the first cosine, $\cos(2\pi(x - U_s t)/l)$, scaled by a constant $c_0$ (the amplitude of the next cosine in $[p]$, $k = 3$, is damped by a relative factor of $3^5$). The constant $c_0$ is determined by inserting $h$ into (3.16) and setting the power output equal to $S$: $$c_0 = -S \left( U \int_0^l (D^{-2}[p])^2 \, \text{d}x' \right)^{-1}. \quad (4.24)$$ The power input for the optimum efficiency solution is found by (4.19): $$P_{\text{in}}' = \frac{SU_s}{U} + c \left( \frac{SU_s}{U} \right)^2 \left( \int_0^l (D^{-2}[p])^2 \, \text{d}x' \right)^{-1}. \quad (4.25)$$ The corresponding efficiency is $$\eta' = \frac{U}{U_s} \left( 1 + cSU_s \left( U \int_0^l (D^{-2}[p])^2 \, \text{d}x' \right)^{-1} \right)^{-1}. \quad (4.26)$$ By explicitly separating out the prefactor $\rho_f \Gamma^2/l^2$ from $[p]$ in (3.8), we can express the efficiency as a function of just two dimensionless parameters: $d/l$ and a dimensionless damping constant $\bar{c}$: $$\frac{U}{U_s} \eta' = (1 + \bar{c} f(d/l))^{-1}, \quad (4.27)$$ $$\bar{c} = cSU_s l^4/(U \rho_f^2 \Gamma^4), \quad (4.28)$$ $$f(d/l) = \frac{\rho_f^2 \Gamma^4}{l^4} \left( \int_0^l (D^{-2}[p])^2 \, \text{d}x' \right)^{-1}. \quad (4.29)$$ In the first optimization problem (§4.1) we found that only the dependence on a single parameter $d/l$ was non-trivial. Considering the Froude efficiency (defined in (4.8)) then introduced a non-trivial dependence on a second parameter $\Gamma/U$. By adding the damping constant $c$, we have obtained a third parameter $\bar{c}$ on which solutions depend non-trivially. Because $\Gamma/U$ appears only in $U_s/U$, we have absorbed it into $\eta'$ (4.27) and $\bar{c}$. This allows us to plot solutions in terms of the two remaining parameters $d/l$ and $\bar{c}$. Flexible body swimming in a vortex street The rescaling of efficiency in (4.27) is convenient because the scaling factor is the undamped efficiency $U/U_s$ (defined in (4.8)). Thus we are naturally able to compare the two. In figure 6 we plot contours of constant $\eta' U_s / U$ given by (4.27) versus $d/l$ and $\bar{c}$. The parameter $\bar{c}$ can be interpreted as a ratio of the characteristic input power required to balance internal damping to that required to work against the external fluid, for a body motion which produces output power $S$. First, we find unsurprisingly that $\eta' U_s / U \leq 1$; i.e. damped efficiency is always less than undamped efficiency. We find also that the efficiency decreases with increasing damping, as expected. As $d/l$ exceeds 1, the efficiency decreases exponentially. The reason is that the amplitude of the pressure jump decreases exponentially as $d/l$ exceeds 1. To obtain a fixed output power $S$, the amplitude of the body wave must then increase exponentially with $d/l$. This increases the damping term in $P_{in}$ ((4.19) and (4.20)) at a higher exponential rate in $d/l$ than it increases $P_{out}$. The result is an exponentially decreasing efficiency. Above $\log_{10} d/l = 0.5$, the amplitude $\max|h/l|$ approaches one, so the small-amplitude approximation is no longer valid for the optimal body waves. We can understand the behaviour of optimal efficiency more quantitatively by an approximate analytical solution. We note that the operator $D^{-2}$ also smooths $[p]$ in $\eta'$, though not nearly as much as for $h$. A good approximation to $\eta'$ is obtained when we approximate $[p]$ in (3.8) by its first cosine component. Using Mathematica 6, this component is $$[p] = \sum_{k=1}^{\infty} p_k \cos(2\pi k(x - U_st)/l) \approx p_1 \cos(2\pi(x - U_st)/l), \quad (4.30)$$ $$p_1 = -\frac{2\rho_f \Gamma^2}{l^2} e^{-\pi d/l}. \quad (4.31)$$ Using this approximation for $[p]$ in $c_0$ and $h$, $h$ is approximately given by $$\tilde{h} = \frac{SI^2}{2\pi U \rho_f \Gamma^2} e^{\pi d/l} \sin(2\pi(x - U_st)/l). \quad (4.32)$$ Here the phase difference between the vortex street and the approximate body shape is $\pi/2$, which is the same phase as for the maximum $P_{\text{out}}$ body shape when $d/l$ exceeds 0.684. For the approximate $[p]$, $\eta'$ becomes $$\tilde{\eta}' = \frac{U}{U_s} \frac{1}{1 + (\tilde{c}/4\pi)e^{4\pi d/l}}. \quad (4.33)$$ In figure 7 we plot the relative error in $\tilde{\eta}'$. We see that it is very small except for larger damping and smaller $d/l$. At smaller $d/l$ the pressure peak becomes sharper (see figure 2), and higher frequencies become important. Thus retaining only the first cosine term can incur a significant error in this region. Because the damping constant multiplies the term which is approximated, there can only be a significant error when the damping constant is sufficiently large. For the approximation $\tilde{\eta}'$, we can easily write down the asymptotic behaviour. For small vortex street width, the efficiency approaches a constant: $$\tilde{\eta}' \sim \frac{U}{U_s} \frac{1}{1 + (\tilde{c}/4\pi)}. \quad (4.34)$$ For large vortex street width, the efficiency decays exponentially with $d/l$: $$\tilde{\eta}' \sim \frac{U}{U_s} \frac{4\pi}{\tilde{c}} e^{-4\pi d/l}, \quad d/l \gg 1. \quad (4.35)$$ This gives a quantitative form for the exponential decay described qualitatively below (4.27). 5. Stability In this work we have assumed that the body is periodic on the length of streamwise separation between vortices. Our intent is to model a body with length on the scale Flexible body swimming in a vortex street of the streamwise spacing of vortices. It is also possible to apply our model to the case of a body which extends over a scale of many streamwise vortex spacings, and then it is interesting to consider whether or not such a body can stabilize the von Kármán vortex street through time-periodic motions. We note that in the literature there are relatively few experimental studies or natural observations of bodies of many vortex-spacings in length placed in a vortex street. Some studies have considered the behaviour of a vortex street in proximity to a solid wall (Bearman & Zdravkovich 1978; Zdravkovich 1983). It is known that the von Kármán street is unstable to infinitesimal disturbances at all values of $d/l$ but one, and unstable to finite disturbances at all values of $d/l$. These facts were reviewed by Saffman (1992), who also described models which try to understand why stable von Kármán streets are common at large but finite Reynolds number. It is an interesting topic for future work to determine the effect of an oscillating body on the stability of the von Kármán street. When the vortices are shed from a stationary body, a sufficiently large background flow, relative to the induced flow of the vortex street, i.e. $lU/\Gamma \gg 1$, can make any such instability a convective rather than absolute one. There is some evidence which suggests that certain motions of a body near the centreline of a point-vortex street may stabilize it. Acton & Dhanak (1993) considered a lattice of sources on the midline of the vortex street, with a periodic distribution of source strength which moves downstream together with the vortex street. They motivated this problem as a basic one in flow control by using flow injection along a solid boundary. They found equilibria in which each vortex in the street executes small periodic motions superposed on constant downstream advection. The distribution of point source strength on the midline is chosen to be locked in phase to the periodic streamwise velocity of the vortex street. The combined flow due to the sources, vortex street, and uniform advection leads to a wavy streamline near the midline. This streamline can be interpreted as a ‘virtual body’ because fluid does not penetrate it. Acton & Dhanak (1993) found that when the phase between the virtual body amplitude and the vortex street is $\pi/2$, the combined motion is stable for certain ranges of the other dimensionless parameters. This is the same phase between the body and vortex street that we have found for optimal power output and efficiency in the case of wider vortex streets ($d/l \geq 0.684$) in §4. 6. Comparisons We briefly compare some of our results with those of earlier work. First, our model predicts that $P_{\text{out}}$ is maximized when the phase difference ranges from $0^\circ$ (for small $d/l$) to $90^\circ$ (for large $d/l$). Streitlien et al. (1996) considered a foil performing a combination of heaving and pitching. The trajectory traced by the foil over a time period is very similar to the shape assumed by our flexible sheet. They did not report the values of $d/l$ they used in simulations, but it can be estimated as 0.2 in their figure 4. For this $d/l$ our model predicts an optimal phase of $15^\circ$, while theirs is $20^\circ$–$45^\circ$ (figure 2 of Streitlien et al. 1996) for simulations with $A/d \leq 0.2$, which approximates the small-amplitude limit. The linearized theory of Streitlien et al. (1996) did consider the small amplitude limit of their airfoil model, and the wide vortex street limit $d/l \to \infty$. Theirs was a regular von Kármán street, in which case our model predicts a Froude efficiency given by (4.8) with $\Gamma < 0$. They see an increased efficiency for increasing $\Gamma/lU$ in their figure 3, which is also shown by our model in this case. For rainbow trout swimming in a flow tunnel, Liao et al. (2003) found that the phase differences between the vortex and different locations on the trout body ranged from 90° to 270° (tail). From their PIV in figure 2, \( d/l \) can be estimated as 2/3. In this case, our first optimization predicts maximum \( P_{\text{out}} \) with 90° phase (for both the regular and reverse von Kármán streets), and our second optimization predicts maximum efficiency with the same phase. Our first comment is that the amplitude in the experiment is perhaps outside the small-amplitude limit. However, because the trout body always remains some distance from the vortices, our model is still reasonable. By matching optimal phases of the fish body and our model, our model suggests that the power savings due to the vortex street is more concentrated on the forward half of the trout (where the phase is closer to that of our optimal body shape) than in the posterior region. An alternative interpretation considers the mean phase of the trout, which is 180°. For this phase, our model predicts zero \( P_{\text{in}} \) (or, with damping, minimum \( P_{\text{in}} \)) and zero \( P_{\text{out}} \). However, the trout possesses an additional means of generating thrust which is not present in our model – by shedding free vorticity into the fluid at the tail. With this addition to \( P_{\text{out}} \), we would expect high efficiency at 180° phase. Apart from the free trailing wake, our periodic model also neglects leading-edge suction, and the free-edge boundary conditions appropriate to the edges of a finite swimming body. This work was supported by the National Science Foundation Division of Mathematics Sciences, grant NSF-DMS-0810602. REFERENCES Flexible body swimming in a vortex street
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Burning on the Shore of an Unknowable Void: Nature as Mystical Reality in the Fiction of Cormac McCarthy Skyler Latshaw Grand Valley State University Follow this and additional works at: http://scholarworks.gvsu.edu/theses Recommended Citation http://scholarworks.gvsu.edu/theses/64 This Thesis is brought to you for free and open access by the Graduate Research and Creative Practice at ScholarWorks@GVSU. It has been accepted for inclusion in Masters Theses by an authorized administrator of ScholarWorks@GVSU. For more information, please contact scholarworks@gvsu.edu. Burning on the Shore of an Unknowable Void: Nature as Mystical Reality in the Fiction of Cormac McCarthy Skyler Latshaw A Thesis Submitted to the Graduate Faculty of GRAND VALLEY STATE UNIVERSITY In Partial Fulfillment of the Requirements For the Degree of Master of Arts English Literature August 2013 Abstract Language, spirituality, and the natural world are all prominent themes in the novels of Cormac McCarthy. This thesis examines the relationship between the three themes, arguing that McCarthy empowers the natural world with a spiritual significance that may be experienced by humanity, but not completely understood or expressed. Man, being what Kenneth Burke describes as the “symbol-using” animal, cannot express reality through language without distorting it. Language also leads to the commodification of the natural world by allowing man to reevaluate the reality around him based on factors of his own devising. Many of McCarthy’s protagonists struggle against the rapid urbanization taking place in the majority of his novels in order to find truth not in the words of man but in the animals and landscape of the natural world, rediscovering a spiritual reality that is mystical, powerful, and true. # Table of Contents Abstract 3 Table of Contents 4 Introduction 5 The Spiritual Significance of Nature 10 The Commodification of Nature 19 The Experiential Power of Nature 41 The Redemptive Truth of Nature 72 Bibliography 79 Introduction Cormac McCarthy is a writer with a staunch, unwavering focus on violence, evil, and immorality. He thrusts his readers into the darkest recesses of the human condition, leaving them to stumble through its depths unaided and without guidance. McCarthy’s writing is full of questions and mystery, but answers are sparse. However, at the same time, it is not void of light in the forms of hope and humor. These serve to bring readers back out of the recesses to discover that, confronted with the reality of such evil and despair, they reemerge more thoughtful and aware of the actuality around them. McCarthy’s search for truth and meaning invariably leads him to address spirituality and the supernatural. In *Understanding Cormac McCarthy*, Steven Frye writes, “When reading even the most disturbing of McCarthy’s works, one must understand that the author seeks truth and value” (5-6), and posits that one of the most important questions that McCarthy asks in his works is “the question of God’s existence and nature, his presence in the world, and his role in steering the course of human lives and world history” (111). While these are certainly questions central to his novels, McCarthy refuses to adhere to a particular worldview, leaving readers with more questions than definitive answers. This has understandably caused some readers and critics to cast McCarthy in a postmodern, humanist light, despite his spiritual themes. In the introduction of his book, *Cormac McCarthy and the Myth of American Exceptionalism*, John Cant writes, “McCarthy’s depiction of man in an absurdist universe is the product of a consciousness that has lost its religious belief but retained a religious cast of mind” (15). The presence of spirituality in the dismal worlds of McCarthy’s work, then, would seem a paradox. Spirituality and religious questions exist—even manage to remain relevant—among grotesque postmodern absurdity. Cant’s assertion that McCarthy retains a “religious cast of mind” only scratches the surface of what the author is accomplishing with his purposeful use of religion, spirituality, and nature. The religious flavor and themes of McCarthy’s works are not simply residue caked on his writing, left over from a faith abandoned; rather, spirituality and mysticism are core concepts McCarthy uses to explore the idea of God and the darker areas of the human condition, and are found to be decisively adhered to the natural world that plays an important role in the majority of his novels. The natural world and animals are exalted throughout the fiction of McCarthy, both through the style of writing chosen to describe nature and the unyielding presence nature has in the novels. A contrast is drawn between the natural world and humanity, a separation that endows nature with a mysterious and sacred “otherness” that man cannot completely grasp, not only due to man’s limited understanding, but also his ability to understand at all. The fact that man operates within the symbolic system of language causes his understanding to always be a step removed from the actual or the true. Nature, however, does not rely on language, but represents only what is. In this way, nature is reality, the warder of truth, and man can only access truth through experience in nature. McCarthy is not a nihilist, but a mystic unwilling to define and confine spirituality through religion and language, instead finding truth and spirituality not through the words and revelation of men or gods, but through the individual, mystical experience of the natural world. McCarthy’s treatment of nature and the relationship he creates between nature and man are similar to Gerard Manley Hopkins’ famous poem, “God’s Grandeur.” In the poem, “the world is charged with the grandeur of God” which “will flame out, like shining from shook foil” and “gathers to a greatness, like the ooze of oil/Crushed” (1-4). These lines evoke both power and mystery. There is a power “fueling” the world, moving and gathering in ways that can only be described through simile. While McCarthy does not definitively attribute the power to God, he too evokes a grandeur that moves in the natural world of his novels. Through his writing style, word usage, and beautiful descriptions of landscapes and wildlife, McCarthy makes the natural world a sacred mystery filled with animals that embody a certain wisdom all their own. However, the natural world in Cormac McCarthy’s novels is not always beautiful, with some locations polluted or encroached upon by mankind. The words of “God’s Grandeur” elegantly relate mankind’s negative effect on the world around him: “And all is seared with trade; bleared, smeared with toil;/and wears man’s smudge and shares man’s smell” (6-7). Hopkins is selective in describing man’s effect on the world and nature: “seared,” “bleared,” “smeared,” and “smudged” all describe the interaction between two separate entities without an intermixing taking place. Although “trade” has “smudged” the world and the world bears man’s smell, man and the world are still distinct and separate, like oil in a pool of water or—in imagery more suitable to discussing McCarthy—trash in a flowing river. Despite the power flowing through the natural world, parts of it are found to be dirty and “used.” Mankind has claimed portions of nature, and the damage is irreversible, as suggested by “seared” and “man’s smell.” A branding is not easily removed, and the “man’s smell” may refer to the idea that nature views the smell of human as an absolute “other,” exemplified in the Old Wives’ Tale that a mother bird will reject a baby bird that a human has touched. Mankind is often depicted as destructive of nature in McCarthy’s work, selfishly using the world for its own gain through trade and commerce. Again, McCarthy and Hopkins agree, with trade playing a fundamental role in the “smudging” of the world. In McCarthy’s novels animals are killed for personal gain, land translated into money and power, and urbanization disconnects man from the natural world. Despite the contrasts and complicated relationship that both Hopkins and McCarthy draw between the natural world and the world of man, both also allow for the opportunity of reconciliation. Hopkins claims that even with all the damage mankind does, “nature is never spent;/There lives the dearest freshness deep down things” (9-10). He uses the image of a coming morning to describe nature’s unending abundance, and uses the rising of the sun as the affirmation of the renewing power of the Holy Spirit (12-3). Nature’s power still resonates, and rebirth is possible. The grandeur that charges the world is still present, and the image of the Holy Spirit bent over the world suggests a coming together, a union that recreates and renews. In McCarthy’s novels, characters experience such union with the world and have encounters that can only be described as spiritual and supernatural. When characters choose to commune with the natural world, they are rewarded with a glimpse into a world that they can only experience without completely comprehending, and they often emerge changed or enlightened. “Return to nature” is a theme throughout McCarthy’s work, with his characters sometimes even taking on the sacred role of guardian of nature and animals. Nature is both blessed and burdened with truth; men, being language- and—therefore—symbol-based animals, cannot inherit absolute truth, because we work and live within symbolic languages and constantly reevaluate the world. The natural world’s inability to distort truth causes Cormac McCarthy to describe nature as spiritual and trust it with administrating truth; if God exists, then nature is the only thing righteous enough to reflect Him. These particular ideas are better articulated in the writings of an ancient Christian Father, St. Gregory of Nyssa. His views on the essence of evil and nature are in line with both McCarthy’s and Hopkins: “There is no such thing in the world as evil irrespective of a will,” and evil is not even a “discoverable substance” (12). He claimed that everything made by God is good, but it is the will of man—apart from God’s will—that brought upon evil (12). The depravity of humanity is met with the sacred of the natural world within McCarthy’s novels and his protagonists find kernels of truth within the mystery of the natural world that surrounds them. By relying on experience, man can transcend the distortion of rhetorical language and find shards of reality in the world. In the McCarthy universe, it is only through interaction with and a desire to understand the natural world that an understanding of truth (and, therefore, a God) is possible. Analyzing the roles that nature, animals, and landscape play throughout the body of Cormac McCarthy’s work—as well as their relationship to humanity—reveals how McCarthy is a spiritually charged storyteller, and not simply a “religious writer in a Godless world,” as John Cant believes. Although his novels are fraught with violence, depravity, and greed, these things are rooted in the materialism of human commerce; a seed of mystical truth can always be found in the natural world that is—despite man’s inability to completely understand it—always renewing, and enough to overcome the distorted rhetoric of humanity in order to redeem the deeds of the individual and allow mankind to reunite with a deeper reality than it is accustomed to, albeit one both terrible and awesome. The Spiritual Significance of Nature Nature and landscape take on a life of their own in McCarthy’s novels. The author’s unique style and language often push the backdrops of his novels into the forefront, allowing them to shape the themes and situations of the story as much (if not more) than the characters. Particular writing techniques, such as the frequent use of archaic and esoteric word choices, bestows nature with power. Much of the power is endowed by McCarthy’s style, and the use of certain writing techniques, such as a heavy use of archaic and rarely used words. Some characteristics of his writing—especially the implementation of many conjunctions within a sentence, a rhetorical device known as polysyndeton—are shared with those found in the Christian Bible, giving McCarthy’s descriptions of nature a religious and spiritual tenor to any Western reader. These style choices are coupled with vivid, mystical descriptions of the world through which characters move, and these descriptions often infuse the natural world with a spirituality and otherworldliness absent in the city landscapes of the novel. This combination of style and descriptions makes nature a window through which man can glimpse truth, a conduit that can spark a spirituality not based on knowing and human ritual, but on a primal mystery that must be experienced instead of understood. The stylistic techniques that McCarthy most often uses follow him throughout his career, molding and shaping the landscapes whether it be the Tennessee valleys, the Mexican borderlands, or the dystopian east coast. Only those with the most robust vocabularies can read a McCarthy novel without having a dictionary close by. Words such as “atterdemalion,” “lazarous,” and “enfilade” intermingle seamlessly with more common language and particularly create a stark contrast to the simplistic, regional dialect observed in the character dialogue. Use of such words has divided critics into two camps: those who see the use of these obscure words as a gimmick, a quirk, or pretentious, and those who view them as an element that creates an additional, meaningful layer to the text. It is difficult, however, to not acknowledge that these words are extremely purposeful and well-executed, masterfully altering the reader’s perception to see in a new light what may seem commonplace and mundane. In relation to nature and landscape, the use of these obscure and archaic words certainly heightens the allure and mystery of nature, and the words themselves practically become a fixture of the worlds McCarthy creates. In a pragmatic fashion, the use of words that most readers will not know adds a factor of inaccessibility to the world being described; these words, if unknown to the reader, either require them to try to understand the meaning through the context and their knowledge of etymology, or to consult a dictionary. Regardless, mystery still is present. If readers try to speculate on the meaning based on context or etymology, they will be only making an educated assumption, and the whole of the definition and meaning will still remain beyond them. The same is true for the readers who consult a dictionary; if they find the word in the dictionary, the definition is sure to be complex and multi-layered. These reactions create a tension within the very fabric of sentences, creating dark places in paragraphs that the reader must stumble or feel his or her way through, a purposeful vacuum of meaning that gets at the mystery of nature in a tangible and interactive way. The words themselves embody aspects of what McCarthy perceives in nature as well. These words are out of use and archaic, parts of vocabularies that have been stripped away. Partly this is because they are deemed to no longer hold a function in everyday speech: other, more familiar words and combinations have taken their place as the quantity of words in registers and vocabularies shrinks. As humankind becomes more urbanized, the proximity to the natural world is diminished, and nature is no longer as valued or so frequently thought of. However, McCarthy values these forgotten words, much as his novels value the idea that nature is sacred and meant to be learned from and respected. Just as his archaic words are specific while at the same time endowed with a certain mysticism, so too is nature “the thing,” “the creation,” a reality man is incapable of knowing and understanding in its entirety. Both the archaic words and the mystery of nature take work and perseverance to understand. The archaic words of the novels are tangible grains of salt sprinkled throughout McCarthy’s novels, familiarizing the reader with the taste of mystery and truth that McCarthy weaves into nature. Less tangible (but equally powerful) is the archaic words’ ability to take the usual and ordinary and transform it into something mystical and supernatural. Steven Frye claims that a feature of McCarthy’s style is the “selective placement of obscure, specialized, or archaic words, which serve the purpose of heightening the mysteries of the natural world” (26). Such words create a persona for the elements and animals of nature, providing them with characteristics that differentiate them from the world of man. For example, after Uncle Ather wakes from being knocked unconscious by a falling tree, McCarthy writes that he “heard the rain mendicant-voiced, soft chanting in that dark gramarye that summons the earth to bridehood” (184). “Mendicant”—meaning a beggar or a friar without property—makes the rain something more destitute and spiritual, and provides a more defined role or position for the rain than merely describing the rain as “a beggar” or a “homeless friar” would. “Gramarye”—occult learning or grammar—injects literal supernaturalism into the scene, adds a layer of ancient and Pagan mysticism and magic to the scene, as if Uncle Anther awoke in some fairy world. “Mendicant-voiced” and “gramarye” personify the rain in a way that paradoxically defines the rain’s relationship with its “bride,” the earth, but at the same time shrouds and confuses the rain’s intensions. This single sentence works to create an unknowable truth in the elements of nature: in this passage, within the rain. The rain is not merely a process, but something more, something interconnected with the ground in a ceremonial, religious way. The use of specialized words gives the natural world a soul, makes it and its elements distinct beings with purposes far greater than simply being understood and controlled by man. Instead, their purposes are unknowable, ancient, and true. Along with his word choices, McCarthy’s rhetorical style serves to define nature as spiritual and enlightened. This style is heavily defined by the narrative voice in his novels. In his examination of the narrative voice in The Crossing, Alan Noble distinguishes the narrative voice with two registers: a lower register and a higher register. The lower register is used to “simply describe action,” while the higher register is composed of fantastic or alien similes that mark McCarthy’s “vatic style” (241). Both of these narrative registers use their unique characteristics to elevate the natural world and infuse it with spiritual and mystical connotations. The lower narrative register is often used in passages of description. Descriptions of the landscape receive the most Biblical rhetorical treatment from the author, leaving the natural world charged with a quiet power, much like the world in “God’s Grandeur.” In his overview of the writing styles apparent in All the Pretty Horses, William Spencer claims that the “one overriding, ultimate rhetorical goal” of McCarthy’s writing is to “establish a pervasively mystical style” (“On the Range of Styles” 58). Spencer is referring to “not only [McCarthy’s] repetitions,” but also “the way he combines words and sentences” (59). McCarthy relies heavily on the style techniques of polysyndeton and parataxis in most of his writing, which are respectively the use of several conjunctions used in succession and the placing of clauses one after another. Noble also addresses these techniques in his analysis of the narrative lower register, positing that they tend to distance the narrator from the story and characters and create a narrative that is “sparse, sterile, and empirical, focusing on the details of the action without passing any judgment on them” (241). These techniques—repetition, polysyndeton, and parataxis—are familiar to any Western reader, because they are common techniques used in the Bible. Genesis 7:22-24 provides an example: “And every living substance was destroyed which was upon the face of the ground, both man, and cattle, and the creeping things, and the fowl of the heaven; and they were destroyed from the earth: and Noah only remained alive, and they that were with him in the ark” (*New American Standard Bible*). McCarthy writes many sentences that mimic this style, such as this one from *Suttree*: “All the weeds were frozen up in little ice pipettes, dry husks of seedpods, burdock hulls, all sheathed in glass and vanes and shells of ice that webbed old leaves and held in frozen colloid specks of grit or soot or blacking” (164). The connections between these phrases create what Hebrew scholar Robert Alter labels as “discrete events,” and are a window into the “way the ancient Hebrew writers saw the world, linked events in it, artfully ordered it, and narrated it” (*Genesis* xvii). This ordering and synthesizing of discrete micro-events contributes to the mystical style of McCarthy’s writing. The writing becomes always moving and connecting, creating an almost unconscious and unnoticeable significance to everything, right down to the frozen weeds. Fluidly connecting events and descriptions of nature not only connotes a mystical “oneness” within the natural world, but also allows McCarthy to refocus language on the reality of nature, to speak of it in its own language. Alter, writing in *Pen of Iron* specifically about McCarthy’s *The Road*, proposes that “the basic challenge for [*The Road*] is this: how do you use language to represent an order of reality fundamentally alien to the reality in which and for which our shared language has been framed?” (172). While the post-apocalyptic world of *The Road* is certainly foreign and unlike anything mankind has seen before, the challenge can be applied to most of McCarthy’s novels as they attempt to describe the reality and spirituality within nature that is alien and lost to urbanized mankind. Alter observes that “the stylistic affinity with the language of the Bible, ‘that old tongue, with its clang and its flavor,’ is never entirely separable from an engagement with the ideas and the imperative values of the Bible” (178). The language and style of the Christian Bible inherently invokes ideas of God, spirituality, morality, and the afterlife. McCarthy uses the higher register of the narrative voice to push his style beyond its limits and channel it into the mystic vein of the Bible, thus infusing his writing with both the supernatural and the immortal. The natural world of his novels becomes connected, timeless, and vast, like a bridge between the supernatural and mankind. McCarthy’s treatment of animals especially attests to the idea that nature possesses a spiritual “otherness” that separates it from mankind. These sections are often written in the higher register, which Noble claims is used to suggest “some profound meaning” underlying otherwise mundane action (241). It is as if animals stem from a world set apart from the depravity of the human world, a plane of existence outside the realm of human understanding. One of the most prominent examples is in All the Pretty Horses. As John Grady begins to break a wild stallion, McCarthy writes that John Grady could feel “the hot sweet breath of it flooding up from the dark wells of its nostrils over his face and neck like news from another world” (103). “News from another world” is both mysterious and spiritual; the essence of the horse comes from some other place, and that the breath is described as “news” suggests that it has some purpose for John Grady, that it is something to share with mankind. The spiritual nature of the horse is specifically the subject of several passages within the novel. Luis tells John Grady and the vaqueros that the soul of a horse “could be seen under certain circumstances attending to the death of a horse because the horse shares a common soul and its separate life only forms it out of all horses and makes it mortal” (111). He says that the soul of the horse is “a terrible thing to see” (111), perhaps meaning “terrible” as in invoking fear upon coming in contact with something so unknowable and beyond man. When John Grady asks if the same is true for the souls of men, Luis states that “among men there was no such communion as among horses” (111). This contrast between the souls of horses and the souls of men is essential to understanding the spiritual truth within horses; there is a connection within the natural world that man does not share in and cannot access. Luis’ use of the word “communion” suggests Holy Communion, which adds a sacred aspect to the souls of horses and further strengthens the idea of a spiritual ritual that takes place between horses that is not practiced between men. Not surprisingly, a similar theme is found in The Crossing, the sequel to All the Pretty Horses. As the novel opens, Billy Parham leaves his bed to witness wolves hunting antelope. The scene is fraught with spiritual significance, as the antelopes’ breath “smoked palely in the cold as if they burned with some inner fire and the wolves twisted and turned and leapt in the silence such that they seemed of another world entire” (4). “Inner fire” suggests a divine spark or breath is within the animal, and is reminiscent of the otherworldly breath of the horse in All the Pretty Horses. That the wolves seem of another world only reinforces the supernatural intonation of this scene, and the language serves to make this hunt a noble and sacred practice, one that has gone on since the dawn of time. Billy’s intrusion upon the scene makes it seem even more sacred. It is as if he stumbled on a new plane of existence and experienced something beyond his normal reality, and it is telling that when he returns home he does not tell his brother what he saw, and McCarthy makes it a point to say that he will never tell anyone (5). Perhaps Billy knows he would not be able to explain the event properly, or believes that the scene was only for him to witness. Billy experiences the otherworldly nature of the wolf again later on in the novel. He wakes one night as he is taking the she-wolf to Mexico, and she watches him as he tends the fire: “When the flames came up her eyes burned out there like gatelamps to another world. A world burning on the shore of an unknowable void” (73). McCarthy invents the word “gatelamps” to describe the eyes, combining the boundary and admission of a gate with the enlightening and guardian characteristics of a lamp. The she-wolf is a signpost for a world that Billy experienced the night the wolves hunted antelope, a world at the fringe of an “unknowable void”—the dark, primal mystery of the universe. This primal mystery is inherent in the world Billy sees in the eye of the wolf, “a world construed out of blood and blood’s alkahest and blood in its core and in its integument because it was that nothing save blood had power to resonate against that void which threatened hourly to devour it” (73-74). Blood represents everything in this other world. Blood is what holds it together, is the answer to everything, and is the only thing there really is. Although this is a rather dark and violent image, in the realm of animals (especially carnivores), blood is existence. It is the essence of life. Blood has always had mystical characteristics throughout the history of man, a fluid long associated with magic, power, mystery, and spirituality. McCarthy writes that blood is the only thing with the power to hold back “the void,” whether it is death, eternity, or something utterly unknowable, and the invocation of the Christian idea of sacrificial blood paying for sin and thwarting death cannot be denied. By looking into the eyes of the wolf, Billy sees into another world, the simple reality by which nature still abides. Billy’s vision of the world within the eye of the she-wolf hints at the complex role nature plays within McCarthy’s work. The use of specific archaic words adds mystery and depth to the natural world. Through his writing style nature is elevated to a spiritual and supernatural level, endowed with the weight, scope, and fluidity of Biblical language. As in “God’s Grandeur,” there is a mystical power at work behind the scenes of the natural world, hinted at through the breath and the eyes of animals. However, just as Hopkins’ poem asks the question, “Why do men now not reck his rod?” (4), Cormac McCarthy addresses the relationship between nature and contemporary man. Although his style and descriptions make nature a sacred mystery, the societies within his novels and most of the characters do not see it that way. McCarthy’s novels suggest that there is a growing disconnection between nature and humankind. Humans cannot fully grasp the reality that is found in nature and animals, but most people have turned away from being able to even experience it, blinded by city streets, trade, and individual concerns. The Commodification of Nature Just as in “God’s Grandeur,” McCarthy’s fiction answers the question of why men do not “reck the rod” of God—or, in other terms, to respect and acknowledge the truth and reality within nature—with “trade.” The landscape may be beautiful and sacred, but it is also being encroached upon by civilization. Many of McCarthy’s novels, such as the aptly named Border Trilogy, take place in “border” locations and time periods that are transitioning from the rural to the urban, or feature locations that are on the border of a city and the wilderness, such as Knoxville in Suttree. The building of cities and fences in itself is not necessarily “evil,” or an affront to the natural word, however; nature, in its immensity and timelessness, is not threatened by the works of man. With urbanization, the party in danger is mankind, whose cities and fences disconnect individuals from the natural world. The food of the individual no longer comes from the land, but the grocer; water, through a faucet; clothing from a tailor. This is all accomplished through trade, and a byproduct of this convenience and efficiency of an urbanized society is that the natural world—although the primary source for all these things—is not acknowledged as such, and man becomes wrapped up in a comforting yet skewed worldview that prevents man from even experiencing or searching for the reality of the natural world. The specific process of trade that causes man to skew reality and reassign values to the goods and resources around him is commodification. Commodification in its simplest definition is the transformation of an entity into a good. Marx defines commodities as “products of labour,” and explains that this quality is an abstraction; commodities are not viewed as the materials that make up the commodity, such as the parts of the chair, or even for its use-value, such as the chair being a comfortable place to sit (38). Instead, the existence of a commodity “as a material thing” is “out of sight,” and all commodities are “reduced to one and the same sort of labour, human labour in the abstract” (38). Commodification, therefore, is an anthropocentric abstraction, reestablishing value based on its tradability with humans in the “currency” of labor. How an entity is commodified is not a universal process, but when it comes to commodifying nature, some processes are more common and heavily relied upon. Geologist and professor Noel Castree, for instance, argues that there is no “single path” to commoditization, that commodification is some combination of six aspects: privatization, alienability, individuation, abstraction, valuation, and displacement (279-82). Of these, individualization, abstraction, and displacement all play a role in severing man’s connection with and understanding of the natural world as a whole by replacing it with a connection and understanding to compartmentalized “pieces” of nature that, without being interconnected to other parts, are not necessarily viewed as part of the natural world by the consumer. Individualization is the act, both representational and physical, “of separating an entity from its supporting context” (280). This allows for the entity to be bought and sold after stripping it of its status as a natural phenomenon and applying “qualitative specificities” to make exchange and the act of assigning monetary value possible (280). Abstraction is the process of taking this now individualized entity and assimilating it to the “qualitative homogeneity of a broader type or process” (281). The individual entity, stripped of its context, is now categorized in a category based on the qualities it has been assigned, which makes it “the same” as anything else within that broad category. Castree exemplifies abstraction with a report about the United States government using the generic category of “wetlands” to label practically every wetland in the country and thus treating them all the same, ignoring much of their unique characteristics and locations (qtd. in Castree 281). An individual wetland is now considered interchangeable with any other, even to the point that the government begins trading off wetlands in some locations for the creation of man-made wetlands elsewhere, “a tradeoff that can be monetarily costed” (qtd. in Castree 281). While individualization strips entities of their context, abstraction strips them of their uniqueness, leaving them only quantifiable by designated characteristics. Displacement Castree defines as “something appearing, phenomenally, as something other than itself,” involving a set of phenomena “manifesting themselves in a way that, paradoxically, occludes them” (282). Displacement is similar to Marx’s idea that the material and physical dimensions of a commodity are “out of sight,” the context of it replaced by its value in human labor. When a commodity is sold by a commodity producer to a commodity consumer, the consumer is “blind” to the connections, context, and individuality that the entity possessed before commodification, and to the effects that producing the commodity may have caused (282). For example, a man buying a diamond ring from a jeweler based on its low price likely will have no idea that that low price is because it is a blood diamond extracted through means harmful both to the environment and to workers. Displacement not only allows but also demands that the consumer be oblivious to the context, individualization, and production of commodities; in relation to the natural world, this means that the natural world either becomes a resource to mine or, more often, is not even considered in daily life since one no longer must rely on it to live, instead relying on society and economics. Mankind’s unique ability to skew and reevaluate the natural world stems from the use of language. This is not simply “communication”; animals besides humans communicate, but in limited and literal terms, generally very simple signals for danger or for food. Language, on the other hand, is complicated and sophisticated enough to allow human beings to reorder events and recalibrate values. This is depicted when the captain in All the Pretty Horses tells John Grady that the Mexican police have the “power to make truth” (168). John Grady’s answer is his mantra throughout the novel: “There aint but one truth,” he says, “The truth is what happened. It aint what come out of somebody’s mouth” (168). He makes a similar point when Mary Catherine asks, “Everything’s talk isn’t it?” and he replies, “Not everything” (28). John Grady’s view of truth being “what happened” is representative of all McCarthy’s novels. As each explores the idea of truth, truth is elevated as something not only rare and fragile, but sacred; the question of whether truth can be articulated or represented becomes an issue not of good or evil, but of man or nature: to distill it further, of symbol or reality. Language may aid man in ordering and explaining the world around him to himself and his fellow man, but it is an articulation that distorts and manipulates that world. The connection between language and truth can be better understood through the work of Michel Foucault and his idea of “the will to truth.” In his lecture “The Discourse on Language,” Foucault finds that the Western world has historically understood the concept of discourse and language as having preexisting meaning by being grounded in nature. He writes, “I am thinking of the way Western literature has, for centuries, sought to base itself in nature, in the plausible, upon sincerity and science—in short, upon true discourse” (219). However, Foucault states that “true discourse” cannot recognize the “will to truth which pervades it” and that “the will to truth, having imposed itself upon us for so long, is such that the truth it seeks to reveal cannot fail to mask it” (219). No matter the purity or basis of the discourse, it must be processed through humanity’s will to truth, which is always and inescapably fueled by desire and power. “Thus,” writes Foucault, “only one truth appears before our eyes: wealth, fertility and sweet strength in all its insidious universality” (220). The “will to truth” turns out not to be the will to the truth, but the will to a truth, a truth that man inevitably makes for his own comfort and gain. Even if nature is the source of discourse, man cannot utter words without them being driven by desire or power. Therefore, the masking of truth in discourse is inevitable. This does not necessarily mean that there is no truth, but that it must be sought through some method other than language. Foucault’s short posits about power, truth, and language connect well with Kenneth Burke’s writing on language and man. Burke perceives language as a rhetorical function, “symbolic means of inducing cooperation in beings that by nature respond to symbols” (A Rhetoric of Motives 43). Burke also saw language as the separating factor between humanity and nature, describing man using the tongue-in-cheek definition of “the symbol-using, (symbol-making, symbol-misusing) animal, inventor of the negative (or moralized by the negative), separated from his natural condition by instruments of his own making, goaded by the spirit of hierarchy (or moved by the sense of order), and rotten with perfection” (“Definition of Man” 507). Burke highlights the negative effects language has on humanity; man alone has the ability to “misuse instruments of his own making” in order to reinvent truth and value. Since man is a “symbol-using” animal and the symbols cannot accurately represent the thing they signify despite man’s “perfectionist principles,” man’s understanding of truth can be (in fact, must be) skewed. If the inherent subjectivity and symbolic nature of language are the great distorters of truth and value that Foucault and Burke make them out to be, then the natural world—being without language—holds the only definitive truth. What is, is, regardless of man’s inability to articulate it in its completeness. Earlier in “Definition of Man” Burke uses the clause “separated from his natural condition by instruments of his own making” to describe man (503). Burke cites inventions and devices as what allows man to somewhat depart from the animalistic/survivalist needs of food, shelter, and sex. However it is language’s role as the backbone of the society that allows for this departure. The languages man has created separate him from “his natural condition,” which can be taken as separation from nature itself. In this way, it is a separation from reality in favor of a “pseudo-reality,” created through the processes of commodification. Trade and commodification are the root of all evil in Cormac McCarthy novels and the cause of much of the violence for which McCarthy is so well known. In *The Orchard Keeper* and *Suttree*, hawks and bats are killed simply for the bounty that has been put on them by the government. In *Blood Meridian*, Native Americans are hunted down for the price their scalps bring. *Blood Meridian* is notorious for being McCarthy’s most mindlessly violent novel, and it is not a coincidence that it is also the novel that centers most on commerce. In *Notes on Blood Meridian*, John Sepich’s excellent guide to McCarthy’s most historical and difficult novel, Sepich describes the Ganton Gang as a “group of businessmen, in this novel of businessmen” (10). Trade is the vehicle of greed and violence in *Blood Meridian*, commodifying the scalps of Native Americans and, in turn, the Native Americans themselves through abstraction and valuation, the redistribution of value and worth. Commodification creates such a powerful contrast between humanity and the natural world because commoditization only exists in the human world. Animals only understand objects, situations, and other animals by their inherent or practical value. As morbid an example as this may seem (and one akin to *Blood Meridian*), a bird could not understand the value of a scalp beyond its practical use, such as the hair being good material for making a nest. There is no recalibration of values, so there is a certain constant “truth” in the workings of the natural world that makes it sacred compared to the arbitrary commodification of human society. This inability of contemporary man to recognize nature as a sacred truth is a theme throughout McCarthy’s fiction, but is most directly addressed in *The Crossing*. Early in the novel Billy learns how to trap wolves from Don Arnulfo. Although the woman tending Don Arnulfo calls him a *brujo*—a warlock—he is better described as a mystic. After Billy explains that he wants to learn a trapping strategy from the old man, they fall into a spiritual and philosophical discussion of the wolf. “*El lobo es una cosa incognoscible,*” Don Arnulfo tells him (45). The wolf is an unknowable thing, and the thing that is caught in the trap is no more than “*dientes y forro*”—teeth and fur (45). There is an essence to the wolf that cannot be accessed, a wolf soul that is more than the sum of its parts, something man forgets or does not know. Arnulfo continues to say that neither the wolf nor what the wolf knows can be realized by man, and that it is like asking to know what the stones know, or the trees, or the world (45). Don Arnulfo is making the point that the world and man operate on different planes of understanding. He is not saying that the wolves know nothing and to ask what they know is like asking what a stone knows. Instead, he is saying that what the wolf knows is as incomprehensible to man as any other element of the world—that nature holds an understanding of truth unknown to man. As Billy struggles to understand, the old man elaborates: McCarthy writes, “[Arnulfo] said the wolf is a being of great order and that it knows what men do not: that there is no order in the world save that which death put there” (45). The wolf understands the reality of the world; there is death and death only to order it. Life is simply the holding back of death and, as Billy will see within the eyes of the she-wolf, it is blood that staves off death and brings meaning to all things. Unlike the wolf, man is preoccupied with other things—elements exclusive to mankind—and misses the literal reality that the natural world holds. Man is distracted by what he perceives and how he perceives it in relation to other men; there is no interspecies communion as there is between the wolf, the stones, and the trees. Don Arnulfo tells Billy that men “see the acts of their own hands or they see that which they name and call out to one another but the world between is invisible to them” (46). In man’s focus on his tangible actions—what he does in the world—and the intangible language he uses, the precise actuality of the world is lost to him. The essences and reality of the world are lost to the “things” of the world, labeled with the language of man, becoming containable and understandable but also becoming something entirely diminished. Arnulfo is aware of this tendency in man, saying to Billy, “Maybe you want the skin so you can get some money. Maybe you can buy some boots or something like that. You can do that. Where is the wolf?” (46). Arnulfo supposes that Billy only sees the wolf in relation to himself, probably as a source of income. In so doing, Billy is not concerning himself with the actual wolf but its defined, commodified parts—parts that he views as valuable because society has deemed them so—and the wolf in its entirety is lost through this commodification. Don Arnulfo suggests here that it is trade and commodification that keeps man from seeing the invisible world of nature; as Marx wrote, the wolf is “out of sight.” Man has difficulty seeing the true reality in nature because he works in a revaluated reality in which nature is redefined in its relation and use to mankind. Don Arnulfo says that the wolf is like a snowflake, and that if Billy catches it, he loses it; he may be able to glimpse the “dechado”—the design, or paragon—but he will not see it in its entirety (46). He may be suggesting that freedom is an essential characteristic of the wolf’s design, but his words also suggest that by trapping the wolf, Billy will “own” the wolf, and by doing so will only be able to see the wolf defined within the “acts of his own hands” or “that which he names”—essentially, within the abstraction and valuation aspects of commodification. In doing so, he misses the “paragon,” or optimal characteristic, of the wolf. The commodification of the natural world essentially reduces it to its components and blinds man from seeing it in its actuality. Although the natural world is too immense for man’s commodification to damage it on the whole, man’s commodification of individual, natural entities surely impacts the entities negatively. When man infringes on nature, something decays on both sides. The orchard in The Orchard Keeper is a representation of this: the neat, organized rows of trees are dying; it is abandoned and in shambles, the limbs of the trees barren of fruit. The workers and owners abandoned the orchard when it was no longer profitable, and with the trees’ fruit taken away and sold there are no seeds to continue the generations of trees. Not only are the trees dead, but there is also a human body in the orchard’s pit, embalmed in water and covered with cedar plank. Nature and man cannot exist together in this environment harmoniously when man only views nature in light of its use value. However, McCarthy takes this point even farther, suggesting that man somehow corrupts nature and has a dark influence upon it. This dark influence is most apparent in the animals of McCarthy’s novels, especially when comparing domesticated and wild. In Animals in the Fiction of Cormac McCarthy, Wallis Sanborn identifies a common formula to organize animals into a hierarchy based on “proximity to and dependence upon man, in conjunction with locus in the natural world” (28). The Orchard Keeper has one of the most prominent: a feline hierarchy. The order is based on how closely tied to humans is each cat, ranging from the domestic housecat to the supernatural wampus cat. What Sanborn finds is that the housecats—which are closest to humans and completely dependent on them—are the sickest, most helpless and suffering of the cats (27). The panther, on the other hand, is the cat that has somehow usurped “a deterministic world where man is the most corrupting influence” (28). The “deterministic world” of man is related to commodification, since part of its process is determining the worth of an entity, and then that worth determining that entity’s fate. This idea is strengthened by the fact that the box of kittens Mr. Eller has in his store represents the most polluted and corrupted feline group in the hierarchy. These kittens—new-borns, surrounded by people the entirety of their short lives—are described as “tottering aimlessly” with “stub legs” and having eyes “closed and festered with mucus as if they might have been struck simultaneously with some biblical blight” (180). They are certainly not healthy, but Mr. Eller alludes to kittens that are even worse off, “ones back in the back propped up with sticks” (180). Sanborn speculates that these propped cats are on display and, therefore, dead, and the lack of a specific modifier suggests that these dead cats are in fact domestic cats, not lynx or bobcats (34). Likely a product of inbreeding, these cats are completely dependent upon humans, and have pitiful, aimless lives. They are described as “lost” and one, slipping in a puddle of tobacco, “offered up to the world his thin wails” (182). This is the epitome of pitiful, an impotent and empty sound the only response this blind animal has to the world that shaped him—the world of humanity. Through this cry, however, Mr. Eller sleeps. Of all the cats they are the most closely associated with trade and commodification, living in Mr. Eller’s store, but the old man is ambivalent about them, and seems to forget they are even there; when Sylder remarks that “A Christian’d of drowned em,” Mr. Eller replies, “What’s that?” even though they were just discussing the kittens. The cats do not claim his interest and are not worth his time. Although it is not apparent whether these cats are for sale or not (the girl coming in and taking them suggests not), they are still treated like a commodity, and a rather worthless one at that; one could imagine Mr. Eller treating in the same way an old rusty trap or a trinket that has been in his store for a long time and not sold. The domestic cat that is periodically mentioned throughout the novel represents the next tier in the feline hierarchy. Her genes impart a history of being close to humans, but she is obviously damaged and unwanted, fending for herself. She finds herself on the brink between humanity and nature, sheltering herself in a dirty outhouse and gnawing at any food she can find. She has a “hunted” look, suggesting an existence of mere running and existing, an unfit life indeed. Not as helpless as the sickly housecats, she manages to make a living for a while. McCarthy’s writing treats her more like a human character in the story, giving her her own sections of narration and even glimpses into her thinking, such as when she gnaws on the side of pork-ribs, “pausing now and again to listen to the silence” (174). As she ekes out a living within the realm of humanity, she also finds her assigned position within nature as the owl swoops down and takes her. It is a sudden and natural end of the cat: prey for a predator. It might not seem fair, but it is the way of nature. Next in the hierarchy is the lynx and the bobcat, free and powerful cats that are completely independent of man. They are, however, not at the top of this hierarchy because although they are independent of man, they are not removed from him. Sanborn acknowledges that they are sought after by men for their coats, which have commodity value. Although they are feral felines, the commodification of the animals makes them prey to men, allowing men to revalue them and dismiss them as cats to be sought only for gain. Unlike the housecats, the bobcat and lynx have not been genetically weakened by man, but instead have lost much of their population and territory to humans. The feline that stands apart from the rest in this hierarchy is undoubtedly the panther. The men in The Orchard Keeper are terrified of the panther, a dangerous cat whose coat is too coarse to be worth the trouble of killing it. Without being able to dominate or commodify the panther, the men are unable to “own” the animal, to diminish it to something less than what it is. It is this inability that causes them to feel such fear for the animal and, instead of diminish it, inflate it into something more than it actually is in order to validate their fears. Uncle Ather tells a story of when an owl’s screeching was mistaken by half the town for the howl of a panther, bringing much fear and worry to many. He says that he knew it was an owl and fooled a few men in the bar, saying that he’d seen the animal, and it was nothing more than “a kitten” (149). They find Uncle Ather’s confidence and lack of fear off-putting. Through their fear, the panther is injected with the supernatural and becomes the wampus cat mentioned throughout the novel, a legendary feline of Anglo and Indian lore (Sanborn 28). Unable to reestablish the inherent value of the panther, man uses language to create a false superstition around the cat. The feline is still made into something that is not, which allows the townsmen to cope with having a predator that they cannot control within their sphere of influence. The folklore does not serve to further separate the natural world from man, but instead creates a closer link between them. One variation of the wampus cat myth explains the cat as “the product of feline and woman,” and there is perhaps no greater connection than sex and offspring. This explanation makes the wampus cat even more sinister, yet at the same time more sympathetic. It serves to fit the panther into a predefined relationship with humanity that the men can understand; they fear the panther not because it is a big dangerous cat, but because there is something supernatural about it. Their fear is validated through their mythmaking. Uncle Ather, however, is immune to this mythmaking due to his respect for and understanding of the panther. This is because Ather not only respects the natural world in general, but he also has had several personal experiences with the panther that have allowed him to see through the myths of the animal and gain an understanding of the animal based on the actual “thing” as opposed to the myth. Ather’s understanding of panthers is foreshadowed by an occurrence that happens in Ather’s younger days, an occurrence that encourages him to view nature as a sacred mystery. He meets a black woman on the road who chants over him and tells him about the wampus cats, that “the night mountains” were walked by them and that they have “great burning eyes” and leave no tracks in the snow. “Aint no signs with wampus cats, she told him, but if you has the vision you can read where common folks ain’t able” (59-60). The description of the cat is something powerful and supernatural, but not necessarily something to be feared. In fact, the woman appears to encourage Ather to seek out the cat with a special vision he either has or she has endowed upon him. This encounter sets Ather up to be somehow connected to the legendary wampus cat and its literal counterpart, the panther, and to view them as something spiritual and awful but, at the same time, real and tangible. Ather’s dreams and nocturnal encounters with panthers is proof that the woman’s prophesy has been fulfilled. The wampus cat is something spiritual and mystic, a supernatural being that roams the hills and haunts Ather’s dreams. It is a knowing specter that watches the old man sleep. The wampus cat represents the mystical spirituality of the natural world. The “painter” is a truth: a terrifying truth, but truth all the same. Sanborn puts the panther on top of his hierarchy not because it is the dominant predator of the southeastern United States, but because it is the only cat that “strikes fear into man” (28). Therefore, the panther is not commodified, and the panther is placed within folklore and legend in order to validate man’s fears of the animal. Even though he cannot commodify the panther, man still reevaluates it and views it as something it is not in an anthropocentric attempt to reorder the world around him. While all humankind is guilty of unintentionally skewing the world around him due to his symbolic interaction with it, the embracing of the power to pervert and reorder the world as one sees fit is perhaps the root of all evil. Indeed, in many myths and religions—including The Fall in Genesis—it is knowledge and the taking upon of wisdom and free will that is the curse of mankind. In the Genesis story, it is the literal taking and devouring of the fruit that—for some mystical reason—was forbidden and led to the eternal human condition. Not only that, but Eve was led astray by the fork-tongued serpent as he convinced her that the apple was not as it seemed. “You will not die,” says the serpent, “for God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil” (Gen 3:4-5). The serpent is lying, a deceit exclusive to language. He is attempting to persuade her that taking this mystery that is not hers to take will empower her to “be like God,” to “know good and evil”; essentially, to be able to recreate, redefine, and revalue reality. It is the perverting power of language that convinces Eve to sin, to take the apple and in so doing to take her own will as her own and fall into the first lie of humanity. In this way, language is endowed with all the creative power of God, while at the same time tainted with the illusionary ability of Satan. One of the most controversial and studied characters in McCarthy’s fiction—if not the most controversial and studied character—perfectly embodies the dichotomy of creator and deceiver that is found in language. Judge Holden, the antagonist of Blood Meridian, has been critiqued in all kinds of ways, from being the true absurd hero of the novel to being Satan incarnate himself. The reason that he is able to put on so many different roles and be read in such varying ways is that he stands for a complex theme: the human condition. Judge Holden is a larger-than-life character that McCarthy uses to play out what would happen if we as humans completely embraced the fall of our race, to not just take a bite or taste of the fruit of knowledge, but to devour and embody what it represented: the yearning for the ability of God to create a reality, but only grasping the ability of Satan to use language and symbol to distort the natural world. The reader is introduced to the judge’s mastery of deceit in the first chapter of *Blood Meridian*, when Judge Holden stands up during a revival and tells the congregation that he knows the reverend preaching and that the reverend is a fraud, imposter, child molester, and guilty of bestiality (7). The reverend denies all this, but the congregation turns on him and presumably shoots him. Afterwards Judge Holden and the gang go to the bar, where after he buys everyone drinks, the Judge is questioned about his relationship to the reverend. “I never laid eyes on the man before today,” he replies. “Never heard of him” (9). In response, the men laugh and buy the judge a drink. The judge is introduced as a ruthless scoundrel, ruining an innocent man’s life for no reason other than that he can. His weapon of choice is simply language; he takes no action other than getting in front of everyone and talking. Of course, this is what the reverend was doing before the judge entered, and the implication of this scene is that words are not only powerful, but manipulative. The revival becomes a battle between two rhetoricians: one a man of God attempting to persuade the people in the tent to see his views, the other a stranger that slanders the reverend out of some form of spite or power-mongering. In this battle of language, it is obvious who the winner is. The judge’s slander easily sways the crowd, even though he has no reputation with those in the revival tent. His false testimony is all that is needed to undo the reputation of the reverend. This is evidence that deceit in language is often more powerful than truth; the snake easily overpowers the word of God. This scene also sets the judge up as an adversary to truth and to God, a theme that follows throughout the novel. This, in turn, makes him an adversary to nature and the reality of the natural world. The judge wants to control the reality around him, to create a reality that exists only through his actions and his words. In order to do this, he attempts to subdue nature and conform it to his own liking. In doing so, the judge becomes one of McCarthy’s most evil and sinister characters, interfering with the only real truth to be found in the McCarthy universe. The judge is not a skeptic attempting to understand the world; he is a cynic who is aware of the reality and immense truth that the natural world has, but instead of attempting to experience this truth, he wishes to manipulate the people around him and Indoctrinate them into his manipulative and skewed worldview in a vain effort to “enslave” nature to his own devices. What makes Holden so heinous is his conscious, driven goal toward deceit and manipulation. While Judge Holden’s initial use of lies is to ruin the life of a complete stranger, he knows the power words have, and uses deceit purposefully throughout the novel. As he introduces Jackson to Spanish-speaking Sergeant Aguilar, he pulls the sergeant aside and quickly tells him a false history of Jackson. The story spans references to Ham and the Israelites, Greek poets, anthropology, and geography (88-9). When Jackson demands that Holden tells him what Holden told the sergeant, the judge simply smiles and tells Jackson that he does not need to “be in possession of the facts” concerning his case, that “his acts will accommodate history” regardless of his understanding what he told the sergeant (89). He goes on to say that Sergeant Aguilar will serve as a third-party witness to “these facts” that Holden has relayed. “Words are things,” the judge claims. “The words he is in possession of he cannot be deprived of. Their authority transcends his ignorance of their meaning” (89). Although the words may not be true, they hold power over the sergeant. Even if he cannot comprehend them, somehow they will live on, disconnected from the actions and reality of Jackson himself; it seems that, in the judge’s mind, this makes them more true than the truth, for it is what this “third party” has been led to believe, and will never have any reason not to believe. Through convincing lies, the judge has altered reality and history and implanted his own variation of truth. Not only is the judge driven to pervert truth and create his own, but also he knows that the source of truth is nature, and manipulates it accordingly. He is not absurdist or faithless: he knows there is an absolute truth, and in knowing this truth means to circumvent it. In a way, he must believe in truth in order to achieve his goal: this makes him perhaps more of a believer than a knower. Tobin recalls a “sermon” that the judge gave at a lava bed: “he concluded with the telling us that our mother the earth as he said was round like an egg and contained all good things within her” (136). The combination of scientific statement—the Earth being round—and mythical statement—the use of “Mother Earth”—is a great representation of the inner workings of the judge who, although a very scientific, educated, and skeptical man, still sees the world through a mystical lens: mother earth still has goodness within her. The twist is that his whole purpose appears to be to undermine that goodness, and to do so with the help of those around him. Tobin says that after the sermon the judge led his horse over the terrain “and us behind him like the disciples of a new faith” (136). The judge is the messiah of a new religion, a new truth he is both a believer and unbeliever in. The judge gives another “sermon” that mixes the scientific and the religious into a mystical understanding of nature that proves that Judge Holden holds nature to be the very pinnacle of truth and reality. After breaking ore samples and talking about geology and the origins of Earth, those around him quote the Bible to refute his “ordering up of eons out of the ancient chaos” (122), and he responds: Books lie, he said. God don’t lie. No, said the judge. He does not. And these are his words. He held up a chunk of rock. He speaks in stones and trees, the bones of things. The squatters in their rags nodded among themselves and were soon reckoning him correct, this man of learning, in all his speculations, in this the judge encouraged until they were proselytes of the new order whereupon he laughed at them for fools. (122-3) The judge may be talking about geology and evolution, but what is really being discussed in this scene is the origin of truth and how it is defined. By saying that books lie, the judge is not specifically talking just about the Bible which the squatters are quoting; he means books in general, compilations of the symbolic words of men, the books of history that—as posited by the aforementioned scene with Jackson—are written by men whose versions of truth and history are easily blemished. The word of man cannot be trusted. However, the unnamed man refutes Holden with the fact that God doesn’t lie, an attempt to give the Bible authority. Holden does not dispute the fact that God does not lie, but instead shifts the word of God from the written pages of the Bible to the rocks on the ground in front of him. God speaks through the natural world, the ever-tangible and experiential world. Fossils and rock serve as evidence of what has come before, and natural laws tell of what is; the ability to experience these things firsthand allows one to experience God and truth, and these things are therefore more of an authority than the words of dead men. This sly manipulation of the judge is effective, and its results are proof of how easily language can steer men toward a comfortable worldview that, while it may not be true, allows them to believe that they have an understanding of the world around them. The squatters change their mind rather quickly and agree with Holden after some encouragement from him, but there is something heinous acting under the surface. After these men become a part of the judge’s “new order,” he laughs at them and thinks them fools for falling for his rhetoric. The judge is not a harbinger of truth, but of lies. He is not interested in bringing enlightenment and truth to anyone, but instead is on a self-proclaimed mission to pull men out of their worldviews and indoctrinate them into his. He did not open the eyes of the squatters and allow them to think for themselves; he expertly pulled them from one worldview based on the words of men into another, based on his own words. He may have argued that God and truth are in the natural world, but that is not what convinced the squatters. The judge’s words—not the experience of nature—are what the men cling to now. The judge knows the inherent truth that can be found in nature, but uses it to his advantage, disproving the views of others with it while indoctrinating them with his own “learned” views. He is not in the business of enlightening men and allowing them to think for themselves. Instead, he indoctrinates them into believing in his words, his religion, thus commanding a power over them that is not as practical as it is metaphysical, an egoistical grasp for symbolic power over those around him. Judge Holden’s desire for symbolic power does not stop at the thoughts of men. He wishes to control the understanding of the world as well. Several times throughout the novel the judge sketches relics into his leather book. He sketches with “a practiced ease,” in “profile and perspective,” pieces of pottery, a scrap of old armor (146). Afterwards, he destroys what he has just sketched. The artifact is no longer part of the natural world, existing only as a two-dimensional symbol kept within the possession of Judge Holden, a part of his collection of knowledge that is not only exclusively his, but also only exists because of him. After sketching several objects then pitching them all in the campfire, the judge “seemed much satisfied with the world, as if his counsel had been sought at its creation” (146). This statement harkens to Genesis 2:19, in which God brings every animal to man “to see what he would call them; and whatever the man called a living creature, that was its name.” However, it is a perverted reenactment of this ritual. It is not a collaboration with God; Judge Holden’s counsel was not sought. Nor is it an act of creation; instead, it is a self-determined reevaluation of the world, a destruction of “the thing” to leave only a lesser, man-made shadow of “the thing” for the judge’s exclusive knowledge. When asked what he is going to do with the sketches, the judge replies that he intends to “expunge them from the memory of man” (147). He is not going to share the sketches, submit them to a museum. The opposite: His book is a graveyard for the history of mankind, where symbols created by the judge are the closest to reality they will get, but they will still not enter the stream of human history. The judge is satisfied with the world because he is actively dismantling and recreating it with his own hand, in his own image, less for his own benefit and more for the rebellious defiance that the cataloging stands for. He is McCarthy’s most notorious villain because he so strongly represents and embraces the evil that is found in all of McCarthy’s work: man’s commodification and reevaluation of the natural world. After pressing leaves and taking notations in his book about local fauna, the judge says that “only nature can enslave man and only when the existence of each last entity is routed out and made to stand naked before him will he be properly suzerain of the earth” (207). He places his hands on the earth saying that it is his “claim” and for it to be his, nothing can live or occur on it without his permission, and that “the man that believes that the secrets of the world are forever hidden lives in mystery and fear,” but the man that tries to see the order in the world and take charge of it can “dictate the terms of his own fate (207-208). The judge views mankind and the natural world in a “enslave or be enslaved” relationship, a struggle of knowledge and influence. Existence outside of the judge’s consent is an insult to him, his authority, and the “claim” he holds on the earth. He does not believe in the sacred mystery that McCarthy endows the natural world with, and that the only option of anyone who does believe in it is to fall into the stupor of superstition. Instead, he believes that everything can be known, the tapestry of life can be unraveled, and it is the responsibility of man to do so. However, the method Judge Holden employs to take control of nature and unravel the tapestry actually proves his method’s fallibility. His ledger is full of shades and symbols created by himself; although he sees this as a triumph over the natural world, in reality it is his downfall. Although he believes he is avoiding the slavery of the natural world by enslaving it, he is actually enslaving himself through his own worldview. He is reordering the world through his own thought, using natural artifacts to create an artificial narrative and then destroying the artifact to make his artificial narrative reality. He is not unraveling the world’s tapestry as much as he is destroying it and weaving his own, consciously embracing the symbolic nature of the human animal. The judge views knowledge as power and the ability to explain and understand is an act of dominance; the belief in mystery and unknowable secrets in the natural world is a sign of ignorance and weakness to him. Judge Holden’s obsession blinds him to another way to interact with nature, one that some of McCarthy’s protagonists—including John Grady, Billy Parham, and Suttree—discover and experience. Instead of viewing the mysteries of nature as completely unknowable and sinking into superstition or treating nature as a powerful enemy that must be overcome through egocentric understanding, these characters experience the mysteries of nature as reality and resist the urge to try to apply manmade meaning or understanding to them. By reveling in the natural world they discover a sacred, almost spiritual truth that they are unable to completely “know” or articulate, yet it still leaves them with an impression of truth and a “oneness” with the natural world that is otherwise lost on humanity. The Experiential Power of Nature Despite mankind’s commodification of the natural world, reconciliation and respect are possible to a certain degree through individuals and their experiences. In fact, people’s relationship with and attitude towards nature may determine how they view and understand themselves more than how they experience the natural world. In What Is Nature?: Culture, Politics, and the Non-Human, Kate Soper defines the term “nature” as “everything which is not human and distinguished from the work of humanity” (15). While this definition may seem rather common and intuitive, the implication is that nature is therefore “opposed to culture, to history, to convention, to what is artificially worked or produced, in short, to everything which is defining of the order of humanity” (15). Nature is not simply an “other” to humanity: it is a force beyond the confines of human order. As Soper points out, components essential to understanding humanity’s story—culture, history, convention—are irrelevant to the story of nature. Although they are separate entities, nature and humanity still interact, however. The defining characteristic of “nature,” being what is void of man and his works, is exactly what man depends on to conceptualize what is “other” to himself and, thus, to define himself. If nature is what humanity uses to conceptualize the other, an individual’s or society’s interpretation of the natural world has a bearing on the individual’s or society’s identity and worldview. Perhaps the most fundamental and influential belief of a society is whether nature should inform humanity or vise versa. In his preface to Lyrical Ballads, Wordsworth defends his choice of everyday situations and rural life as the subjects of his poetry by claiming that in them “the passions of men are incorporated with the beautiful and permanent forms of nature” (265). Wordsworth perceived these subjects as being opposed to “the great national events,” industrial urbanization, and the uniformity of the occupations of city dwellers, all which “blunt the discriminating powers of the mind” and “reduce it to a state of almost savage torpor” (266). Wordsworth believed that the direction society was taking was the wrong one and that poems praising the rural life—a life still connected to the beauty of nature—could redeem humanity and turn it from this path. The Romantics treated nature as a spiritual and redemptive other to mankind. Appearing near the end of the Romantic period, philosopher John Stuart Mill maintained a very different worldview than the Romantics. Embracing utilitarianism, Mill took a detached, scientific approach to nature. Mill defines nature as “what takes place without the voluntary and intentional agency of man,” a definition similar to the one Sofer provides (Three Essays on Religion, 8). However, Mill regarded nature in a negative light, full of irrational, unbridled spontaneity and horrible acts: “[A]ny one who endeavored in his actions to imitate the natural course of things,” writes Mill, “would be universally seen and acknowledged to be the wickedest of men” (65). Inefficient and unruly, nature is not an “other” to imitate or return to, for Mill; instead, it is an other to avoid, and the capable ordering of mankind is what should be embraced. Wordsworth, Mill, and their respective philosophies represent what Sofer labels “nature-endorsing” and “nature-skeptical” responses. Sofer defines the “nature-endorsing” response as viewing nature as what should be sought to bring about in place of “existing actuality” (34). The “nature-skeptical” response promotes cultural determination and views the endorsement of nature as “a dubious move designed to limit and circumscribe the possibilities of human culture” (34). The response that an individual or society subscribes to determines how nature is valued and treated, and whether nature as other is to be emulated or alienated. McCarthy is an author who is acutely aware of how humanity’s response to nature shapes both humanity and nature. His characters can easily be divided by their response to nature. Harrogate and Judge Holden, for example, are representations of the nature-skeptical response, one a selfish and literal rapist of the natural world, representing the ultimate commodification of it, and the other a liar and a prankster, attempting to enslave the natural reality around him. Both characters apply human order to the world, approaching it anthropocentrically, conceptualizing themselves as above nature and the other, losing touch with nature to the point where they do not even interact with nature, let alone experience it. This is also the attitude of the communities in most of McCarthy’s work, illustrated best by the world of *The Border Trilogy*—one of fences and diminishing wilderness, with nearly all the wolves hunted out of the United States and the cowboy an endangered species. Likewise, the slums of McAnally Flats in *Suttree* are torn down to put in an expressway as urbanization continues to detach people from the natural world. The mystery and spirituality that nature possesses is lost on the masses as the “nature-skeptical” response is embraced. Despite the overwhelming push of society against the natural world, McCarthy’s characters still manage to find spirituality and truth within nature, proving that McCarthy subscribes to the nature-endorsing response. Yet again, a parallel can be drawn between McCarthy and Hopkins; the second stanza of “God’s Grandeur” begins “And for all this, nature is never spent” (9). Nature is resilient and abundant, with “dearest freshness” and “deep down things,” invoking a mysterious power of rejuvenation (10). Despite the negative effects of man’s trade and toil, the natural world in Hopkins’ poem is always renewing, thanks to a hidden source of power and the guardian presence of the Holy Spirit. Similarly, nature never loses its mystery and spirituality in McCarthy’s writing, and the truth is always there for individuals to experience it. How exactly the mystery within nature is experienced is, by its very definition, difficult to describe. In *The Spell of the Sensuous*, David Abram claims that civilizations have always had individuals who specialize in connecting with nature on a spiritual level, but Western anthropologists have not always realized the “ecological dimension of the shaman’s craft” (8). Anthropologists, unable to overcome the modern assumption that nature is for the most part determinate, knowable, and methodical, overlooked the possibility that spiritual mystery could be believed to exist in the natural world instead of a supernatural, nonphysical realm (8). If spirituality can be found in nature, then the ability to connect with the spiritual can be a voluntary act of an individual. Abram asserts that the traditional magician “cultivates an ability to shift out of his or her common state of consciousness precisely in order to make contact with the other organic forms of sensitivity and awareness with which human existence is entwined” (9). This parallels what McCarthy describes: in order to glimpse the mystery of nature, man must temporarily shed his own perspectives and come in contact with an element of the natural world. Abram elaborates, writing that not only does the magician slip out of the common state of consciousness, but also out of the boundaries of his or her particular culture (9). In cultures dominated by anti-nature sentiments, McCarthy’s characters certainly fit this definition: Suttree’s spiritual visions in the Smoky Mountains and Uncle Ather’s appreciation for the natural world through his exposure to panthers are examples. The ability to experience the spiritual reality behind nature requires one to view human intelligence as just one of many methods for understanding the world around him or her. Personal, experiential knowledge can provide a proximity to spirituality and truth that is impossible if simply relayed through faulty human language. Not only does language provide the means for commodification and the reevaluation of reality, but it also hinders mankind’s ability to view the mystery of nature and see it as a reflection of spirituality. Abram stresses that the development of the alphabet in particular causes trees to “fall silent” and animals to no longer be viewed as “emissaries from alien zones of intelligence” (130). Mankind no longer experiences nature as expressive or alive because the senses have been “transferred to another medium, another locus of participation” (131). Abram argues that this locus is written text. Mankind finds reality in the written word, in a symbolic alphabet and manmade knowledge. The “magic” that Abram describes is transferred to written text: reading creates visions, voices in one’s head, and vivid experiences. No longer must these visions and experiences come from the reality of the natural world; they are now readily available within the reader’s mind via the ingenuity of mankind. Again, despite this, McCarthy’s characters still find a way to tap into the spiritual mystery of nature. Usually these characters are cultural and social outsiders, if not outcasts, so the influence of society has little sway on them or is outright rejected. This can be as subtle as Billy catching glimpses of wolves hunting at night or as drastic as Suttree’s striking and immediate connection with the earth and landscape in the Smoky Mountains. Whenever this happens the character has his or her perspectives changed, or is put in a vulnerable state wherein nature can break through the character’s state of consciousness and reveal itself. Of McCarthy’s protagonists, John Grady Cole is the most attuned with nature and exemplifies the spiritual experience that can be found in the natural world. It is immediately apparent when reading All the Pretty Horses that John Grady has a way with horses: he talks with them; understands their feelings; is talented at breaking in wild ones. John Grady is also able to sense and appreciate the spiritual quality of horses and the sacredness to be found within them. In his article “In Conflict with Himself: John Grady's Quest in All the Pretty Horses,” Terrell Tebbetts states that for John Grady horses “provide a sanctuary from dispossession and abandonment” (42). Tebbett stresses how important John Grady’s relationship with horses is and how it contrasts with the boy’s human relationships, which only seem to cause him trouble and pain. John Grady possesses the unique ability to not only connect with a non-human animal on a deep level, but to find sanctuary in it, to experience a dark mystery that exists within the natural world. John Grady makes it a priority to stay connected to nature from the very beginning of *All the Pretty Horses*. After his grandfather’s death, John Grady wishes to stay on the ranch and work the land. Unfortunately he is forced off of the ranch because his mother wants to sell it (17). It appears that the time of the Texan rancher has passed; his mother’s lawyer tells John Grady that “not everybody thinks that life on a cattle ranch in west Texas is the second best thing to dyin and going to heaven,” and that it is not a “payin proposition” (17). Nature is not valued at this time in American history, with industrialization blunting society’s view of nature. The way of life John Grady has come to find meaningful and fulfilling is taken from him and fading away, much like the life and legacy of his grandfather: “The Grady name was buried with that old man” (7). Although he cannot completely resurrect the legacy of his grandfather, John Grady still does carry “Grady” as his middle name. Similarly, John Grady carries the legacy of the cowboy and the “nature-endorsing” mentality Soper describes, desiring to remain connected with the land and animals of nature despite the changing world around him. His human relationships have left him wanting. His mother works in San Antonio with little intention of making him part of her life, while his depressed and impotent father is shattered and cannot do anything for him (23). John Grady is heartbroken over Mary Catherine, a girl who apparently chose another boy over John Grady (28). The human world has let him down and he is dispossessed, with no place to call his own anymore, so he decides to leave. When Rawlins asks John Grady if he is really going to run away, he replies, “I’m already gone” (27). John Grady is a social outsider, refusing to give in to the pressures of the present culture, preferring the natural wilderness to the disappointment of human society. John Grady is one of McCarthy’s most sympathetic protagonists, but his dispossession is only part of what makes him so sympathetic. Tebbetts claims that John Grady is “a new kind of McCarthy protagonist” because although he is an uprooted stranger like his predecessors, he is also a “lover” (Tebbetts 37). John Grady has a genuine love for life, people, and animals. McCarthy writes, “What [John Grady] loved in horses was what he loved in men, the blood and the heat of the blood that ran them. All his reverence and all his fondness and all the leanings of his life were for the ardenthearted and they would always be so and never be otherwise” (6). In the beginning of the novel, though, it is difficult to describe anyone in John Grady’s life as ardent. In this context, John Grady’s flight to Mexico can be interpreted as a spiritual quest to reclaim and reestablish his connection with “the ardenthearted,” the true and the real that he experiences in nature and those who appreciate it. The use of the word “blood” to describe what John Grady loves in animals and man is a testament to how connected John Grady is to nature. In *The Crossing*, when Billy looks into the eyes of the she-wolf, he sees an “other world, construed out of blood with blood at its core” (73). Blood is the dark mystery of life, a powerful symbol of what is true yet unknowable in nature and in life. Not only can John Grady sense the “blood” and truth within horses and men alike, but he is also drawn to it and appreciates it for the reality that it is, and loves this reality without being concerned with attempting to completely understand it. It is no coincidence, then, that John Grady is drawn to the wilderness of Mexico. Mexico, in contrast to Texas, is not as developed or established. Upon studying a map of Mexico, Rawlins tells John Grady that “there aint shit down here” (34). This isn’t true, however. What Rawlins means is there are not many cities, towns, and roads. There are vast tracts of wilderness and very large ranches. The wide-open and untamed landscape of Mexico is exactly what John Grady yearns for and greatly contrasts the confining urbanization of the United States, both physicality and the social mindset. John Grady’s journey is a pilgrimage through a raw country where there is room for him to be a cowboy, tend to horses, reconnect with the natural world, and realize his true self; it is a world still dominated by the wild, true spirit of nature. An excerpt from the beginning of the novel sets the tone for the natural spirituality John Grady hopes to find again in Mexico. After his grandfather’s funeral, John Grady rides his horse “where he would always choose to ride,” out where the western fork of the old Comanche road passed through a section of the ranch (5). He would choose to ride “when the shadows were long and the ancient road was shaped before him in the rose and canted light like a dream of the past…. When the wind was in the north you could hear them, the horses and the breath of the horses and the horses’ hooves . . . and above all the low chant of their song which the riders sang as they rode” (5). John Grady chooses to ride along the ancient paths of the Comanche, a people who had a similar affinity and respect for horses, and experienced a similar dispossession. There is also a spiritual aspect to the scene, a harkening to an ancient past and dead people still somehow more alive to John Grady than the living people around him. Edwin Arnold points out in his article “Go to Sleep: Dreams and Visions in The Border Trilogy” that this passage describes “a thing both ancient and otherworldly, and yet McCarthy suggests that this vision is not imagined by the boy or present to him only” (50). Even though John Grady must “turn the pony up onto the plain and homeward,” the “warriors would ride on in that darkness they’d become, rattling past . . . and singing softly in blood and longing south across the plains of Mexico” (McCarthy 6). Again, the use of the word “blood” draws a parallel between John Grady and the Comanche people that came before him. Arnold claims that this passage proves that the vision of the Comanche “exists independent of the boy—these ghostly figures out of the past are still a very real part of the world, whether seen or not, whether ‘alive’ or not. At the moment the boy has the eyes and the spirit to witness them, but they do not depend on his witnessing them for their existence” (Arnold 50). The Comanche have become part of the landscape, part of the nature they communed with, and John Grady is able to connect to them through their mutual love for blood and admiration for the natural world. John Grady’s relationship to the memory of the Comanche in this passage is identical with his relationship to the spirituality of the horses throughout the novel. He possesses the ability to sense what Arnold and *All the Pretty Horses* describe as “ancient and otherworldly,” a reality within the horses and the natural world that is true and independent of John Grady. John Grady experiences this spiritual reality near the end of the novel, in a dream that is as mystic and supernatural as his Comanche vision, but focuses on the differences between nature and humanity. The destiny awaiting mankind is realized: > The horses in his dream moved gravely among the tilted stones like horses come upon an antique site where some ordering of the world had failed and if anything had been written on the stones the weathers had taken it away again…. Finally what he saw in his dream was that the order in the horse’s heart was more durable for it was written in a place where no rain could erase it. (281) This dream suggests that the horse is more permanent than man because it is from or exists in a different place than man. The live horses move among the worn gravestones of deceased men, a site of a failed order of the world; there is not even a trace of it on the writing on the gravestones. This failure of the written word to last is the failure of language, the thing that separates mankind from nature. John Grady realizes that the horse’s heart is “more durable” because it was “written in a place where no rain could erase it,” a mystical way of conveying the spiritual truth that the natural world holds and pointing to the failure of mankind to embrace a reality that will last. The true and the ardent are primarily found in nature, which will endure long after man is gone. As this dream and realization proves, John Grady has a special connection with and understanding of horses and the natural world. He finds connection with the rest of nature through the animal, allowing him to experience the spiritual mystery of the world in a real and emotional way. In his critical essay titled “A Note on Horses in All the Pretty Horses,” Jianqing Zheng writes, “To John Grady, the wild horses symbolize the unfallen spirit in nature that he desires. The description of John Grady’s close relationship with the horses reveals his affinity with nature and the philosophical notion of an essential unity of human beings with the universe that connects the external world and internal emotion.” Zheng’s strong assumptions about John Grady’s connection with horses are supported by a passage near the beginning of All the Pretty Horses. McCarthy describes John Grady by saying that “if he were begot by malice or mischance into some queer land where horses never were he would have found them anyway” (23). It is as if John Grady’s affection for horses is supernatural: “[He] would have known that there was something missing for the world to be right or he right in it and would have set forth to wander wherever it was needed for as long as it took until he came upon one and he would have known that that was what he sought and it would have been” (23). While McCarthy uses this passage to describe just how powerfully John Grady is connected to horses, he leaves as a mystery the reason John Grady would have the ability to sense something was “missing” in a horseless world. Terrell Tebbets argues that John Grady’s connection with horses “stems from his drive to find something in this world adequate to his love” (43). To search for something to pour one’s heart and love into is indeed a spiritual quest, and the fact that nothing but horses is adequate embellishes the idea that the souls of horses and the spirituality of nature are something pure, truthful, and mystical, especially compared to the human depravity that has let John Grady down. Horses are a reflection of distilled goodness, and John Grady has difficulty finding such a reflection in humanity. To John Grady, a world without horses is a world without God, or at least a world without any connection to something higher than man. John Grady’s profound connection with horses is most powerfully apparent after he and Rawlins begin working at Hacienda de Nuestra Senora de la Purisima Conception. He often talks to the horses he rides, reassuring them or calming them. Whether he is aware of it or not, John Grady’s interaction with horses cannot be described as anything less than mystic and supernatural. McCarthy rarely writes what John Grady says to the horses, but it is clear that it is effective and something out of the ordinary. As John Grady begins breaking a colt after arriving at Hacienda de Nuestra Senora de la Purisima Conception, he holds it and tells it “all that he intended to do” and strokes “the terror out” of it (103-4). Although the reader does not know the words that John Grady speaks, their effect is powerful, calming the horse in a way that nobody has seen before, his efforts at breaking the horse drawing a large crowd of onlookers (105). Even on a large Mexican ranch, John Grady’s way with horses and his connection with them are considered extraordinary. Instead of breaking horses through domination, he does so through a deep understanding of and respect for the animal, as if the horse is a partner in this rite. By not allowing the reader to know exactly what John Grady is saying to the horses, McCarthy makes John Grady’s “horsetalk” somewhat of a sacred mystery. The way McCarthy describes John Grady’s horsetalk is similar to Chapter 8 of The Gospel of John. The chapter begins with the story of the Pharisees bringing a woman caught in adultery to Jesus in order to ensnare him in a moral and theological trap. In response, Jesus begins writing on the ground and “when they kept on questioning Him, He straightened up and said to them, ‘Let any one of you who is without sin be the first to throw a stone at her.’ Again he stooped down and wrote on the ground” (New International Version, John 8.7). What Jesus wrote was not recorded, but the fact that He was writing something was; therefore, the act of writing itself is what has an effect on the Pharisees. Although it appears to be Jesus’ spoken words that cause the Pharisees to leave (8.9), the words written played a part as well; perhaps Jesus was writing down their transgressions, something only God could know. The description of John Grady’s horsetalk is similar to Jesus’ writing on the ground. Since the actual words are not recorded, the reader is only allowed to see the results of the act, not the means, and this makes the act something mysterious and supernatural. Although not nearly on the same level as Jesus’ spiritual connection with the people He interacted with, there is a spiritual connection and understanding between John Grady and horses that borders on the supernatural. John Grady does not squander this talent that he possesses for his own gain. He does not talk to horses just to make it easier for them to be broken by men; he views them as having inherent worth as the “ardenthearted” creatures that he loves and respects. Zheng goes so far to say that horses are “like a spiritual bridge between John Grady and nature.” Through the horse John Grady can experience a reality uncontrived by humanity and incomprehensible by humankind. Although John Grady cannot comprehend the truth he loves in horses, he experiences it by breaking, riding, and caring for horses. There are several instances within the novel where John Grady receives a glimpse of the raw spirituality of the natural world through his interactions with horses. After being jailed with Rawlins and Blevins, John Grady has another dream, a dream “of horses in a field on a high plain where the spring rains had brought up the grass and the wild-flowers out of the ground and the flowers ran all blue and yellow far as the eye could see” (161). This idyllic setting, even though it is purely a natural world, has the feeling of being otherworldly. “A high plain” has a heavenly connotation to it, and “as far as the eye could see” suggests that this is a world that goes on into eternity. This is John Grady’s vision of the “other world,” the purely natural world that he only gets glimpses and “news” of through his prophetic experiences with horses. McCarthy writes that “[John Grady] was among the horses running and in the dream he himself could run with the horses” (161). John Grady is not a spectator in this dream world: He is a participant, uninhibited, completely integrated into it. It is a scene of perfection: “…and there was nothing else at all in that high world and they moved all of them in a resonance that was like a music among them and they were none of them afraid horse nor colt nor mare and they ran in that resonance which is the world itself and which cannot be spoken but only praised” (161-2). This is a natural world without the blight of humanity, physically and spiritually in tune with itself. This dream represents what John Grady longs for: oneness with the mysterious truth of the natural world. Although he cannot completely understand or speak of it, he seeks after it and praises it through his connection with and love of horses, and in this particular time of distress, he finds solace in it. Although this dream is ethereal and idyllic, John Grady also has a very down-to-earth and personal connection with the horses he encounters. As he rides away from the ranch for the last time, he talks to his horse and “told it things about the world that were true in his experience and he told it things he thought could be true to see how they would sound if they were said” (242). John Grady is not merely making “conversation” with a horse to pass the time; he is treating the horse as a sounding board to find the truth in his experiences and weed out things that may not be true. John Grady is actively defining himself and his beliefs, conceptualizing himself and using the horse as “the other,” just as Soper’s definition of “Nature” warrants. Instead of commodifying the horse and therefore considering it only based on its value and use to him, John Grady considers the horse as an individual and unique being, a touchstone to help him better understand himself. This idea of the horse as individual may seem to contradict Luis’s proposition of the “common soul” of the horse, but—in actuality—it strengthens it. Luis says, “if a person understood the soul of the horse then he would understand all horses that ever were” (111). He is not suggesting that all horses are identical and if a person understands one, he understands them all; he is saying that they share a soul, and to understand that fact is to understand all horses. There is a truth that is shared in all horses and reflected in each individual, much like Plato’s idea of material and ideal “Forms,” in which the non-material, abstract and perfect Forms are more of a reality than the material forms, which are essentially imperfect or lesser copies of the ideal. The horse is both individual and collective, representing the material, physical horse along with the ideal concept of the horse as a Form, and this “Form” is the collective soul, a mystery that John Grady seems to intuitively sense and experience. The spiritual connection between John Grady and horses is one of the more beautiful aspects of All the Pretty Horses. Despite the upheaval of John Grady’s life by his jaded family, the young boy manages to pursue the truth and reality he has come to know in horses. Through his affection for the animals, he is allowed a glimpse of the “ardenthearted” world that he longs to be a part of. The spiritual and the sacred permeate much deeper than the vocabulary and style of the novel. McCarthy expertly uses the horse to philosophize, contrasting the natural world with the human world in a way that portrays the horse as a true and beautiful thing; the novel lives up to its name. Despite the amount of violence, dispossession, and pain that fills John Grady’s world, he is always able to experience spirituality and truth through horses. Like John Grady, Cornelius Suttree is a McCarthy protagonist who experiences social displacement, turns to a more rural/pastoral lifestyle, and finds truth within the natural world. Unlike John Grady Cole, Suttree is not much of an innocent “lover” who stands up for ideals of justice. Instead, Suttree is a guilt-ridden alcoholic who has willfully alienated himself from his family and is spiritually jaded. Most of the natural world in Suttree reflects Suttree’s disposition as well, polluted and dirty; the Tennessee River and surrounding valley pale in comparison to what they were before the urbanization of Knoxville. Because of the fallen disposition of both Suttree and nature, the spiritual quest that Suttree undergoes is one not only to rediscover something true and beautiful in the mystery of nature, but also to overcome his own demons and rekindle a love for life and the spiritual. For Suttree, the natural world is redemptive, pulling him out of the mire of his own shame and guilt, back into the world of living mystery. Although Suttree’s past is rather shadowy and vague, the decision to alienate himself stems primarily from his family relationships. His choice to leave an upper-crust lifestyle for the poorer, simpler existence of a fisherman on an abandoned houseboat alienates him from his wealthy father. Beyond simple disapproval, his father cannot understand why Suttree would leave. In a letter to Suttree his father writes that if he feels like he’s missing life he can find it “in the law courts, in business, in government” (14). This suggests that Suttree forsook his prestigious upbringing in order to find “life,” to find something more real and meaningful than what he would inherit. Suttree’s reason to hold contempt for his father is apparent when he is talking to his uncle, pointing out that his father “married beneath him,” and therefore Suttree is beneath him as well (19). He believes his father is contemptuous of him because of his mother and her family, that Suttree “was expected to turn out badly” (19). Suttree’s estrangement with and alienation from his father was a complex act of rebellion, a willful search for something “more” in life, and an embrace of the low expectations his father apparently had for him. Suttree’s abandonment of his wife and his son appears to have been a result of similar motives and a source of much shame. A dream Suttree has proves that the contempt and humiliation he feels is shared and intermixed within his relationship to his father and his son. He dreams that a man he took to be his father grabs him in passing, brandishing a knife, but Suttree concludes that “it was not my father but my son who accosted me with such rancorless intent” (28). That the intent was “rancorless” implies that perhaps it is not the son or father that hold power over him, but the guilt and humiliation he feels about abandoning them that makes them accost him in his dreams. There are no details about the circumstances of his leaving his wife and child, however. Only the aftermath is knowable: that he loved his wife and that she and her family hold much grief, pain, and anger over his leaving, expressed when he returns for his son’s funeral. After watching the funeral from a distance, Suttree makes a point to fill in his son’s grave, a meager attempt to do one last thing for his son and the guilt he feels for what he has done. Suttree’s abandonment of his wife and child are a constant weight upon his life and conscience, a weight that causes him embrace the alienation he feels by living in poverty in McAnally Flats. The last familial relationship that causes Suttree guilt is the relationship with someone he never met: his twin brother, who, a breech birth, supposedly died as Suttree kicked him in the head during birth. Already battered by the strained and guilt-ridden relationships with his father, wife, and son, Suttree must ask himself why it was he who unintentionally murdered his “mirror image” (14). The dead twin is another family member whom Suttree betrayed by not living a life worthy of the life given to him. Suttree describes that his brother was the “the ordinary of the second son,” that Suttree “followed him into the world” (14). Suttree grapples with the idea that fate allowed him to live and his brother to die, that perhaps death had chosen incorrectly. The still-born twin still holds so much power over Suttree’s psyche that it is perhaps the shame Suttree feels in simply living that causes him to turn from the prosperous upbringing of his father and seemingly happy marriage with his wife for a life of lonely destitution on the Tennessee River. Although Suttree lives on the river and is routinely traveling into the natural world, his disposition prevents him from having anything resembling a mystical experience. Unlike John Grady’s rancher life that is chosen because of his love for horses, Suttree’s poor fisherman life is one of self-inflicted exile; being an upper-class college boy did not prepare him well for the life he has chosen in the old houseboat. He often catches fewer fish than he would like and has trouble finding buyers in Knoxville. Early in the novel he lies awake and says to himself that in another life he might have been “a fisher of men,” but that “these fish now seemed task enough for him” (14). He is a broken man, out of his element. This fact is apparent to Michael the Indian, who is an excellent fisherman and trapper. Michael tells Suttree that Suttree “won’t stay” on the river (a true prophesy), and when Michael asks Suttree what got him into fishing, Suttree tells him “I sort of inherited my line from another man,” a man that said “not to look for him back” (240). Suttree is living a life of penance in a vocation handed down to him, one not of his choosing. He is not yet seeking truth or pursuing anything within nature; instead, he meagerly subsists off of it, unable to see anything beyond what it can supply to him. However, Suttree’s relationship with the natural world does not remain shallow and stagnant. His spiritual quest begins shortly after he reluctantly helps Leonard perform a burial at sea for Leonard’s father. The fact that Leonard doesn’t even want to “say a few words” over the body bothers Suttree, and after they shove “the thing” into the river, Suttree refuses to make conversation with Leonard (251-252). This death seems to be the grim reminder of mortality that breaks Suttree. The next chapter finds Suttree drunk, stumbling through the Catholic church he attended as a boy. This visit not only provides background for Suttree’s spiritual life, but also serves as the springboard for his spiritual quest, making him restless and reawakening a need for something more than the life he is living. The description of the Church of the Immaculate Conception provides an indication of the spirituality Suttree grew up with and abandoned, a spirituality in stark contrast with the mystical and mysterious spirituality with which McCarthy endows the natural world. McCarthy describes the church as a cold, dead thing: “Beyond the chancel gate three garish altars rose like gothic wedding cakes in carven marble. Crocketed and gargoyleed, the steeples iced with rows of marble frogs ascending” (253). The foliage of the crocket and the frogs are images of nature, but they are part of a showy altar and carved in cold marble, caricatures of the life they represent. The Crucifix is described as “a sallow plaster Christ,” and Mary “treads a snake with her chipped and naked feet” (253). Both descriptions emphasize the hollowness of the statues, mere shadows of the people and the stories they depict. They are worn, manmade icons in a worn, manmade building, with a tabernacle “where the wise high God himself lies sleeping in his golden cup” (253). Even God is a caricature here, dormant, resting in luxury within the church, a deity encompassed by the knowledge of men. He is not a larger-than-life mystery, but a known thing living in space and time, domesticated by man. As Suttree slips into his memories of growing up within this church, he is reminded of the teachers, “grim and tireless in their orthopedic moralizing,” “filled with tales of sin and unrepentant deaths and visions of hell” (254). Suttree associates this church and his religious upbringing with sin, guilt, and hell. Despite the efforts of the priests and teachers, Suttree says that most of the students only managed to learn to read and write, “and that was all”; the religion taught apparently did not take hold, and many, like Suttree, fell away from faith (254). In *The Achievement of Cormac McCarthy*, Vereen Bell writes that Suttree is “left impaled upon the wrong end of a coherent theological dogma in which the world can only be a place of death and suffering and, at best, a dangerous obstacle to salvation” (69). Suttree was taught that the world works in a revealed, logical, and understandable code that leads to redemption, but due to what Bell calls “militant religious instruction,” the redemption is lost in a world of guilt and sin that has imprisoned Suttree. Suttree’s reaction to his schooling has essentially reduced God to the knowable, stripping Suttree’s religion of mystery, leaving only an oppressive shell of regulations and consequences. Despite his drunken state, Suttree’s disdain for his upbringing and the religion that was pushed on him are clear. After a priest wakes Suttree and tells him God’s house is no place for a nap, Suttree responds with the razor-sharp “it’s not God’s house” (255). When the priest begs his pardon, Suttree again states resolutely, “It’s not God’s house” (255). Suttree is aware that the deity sleeping in the golden cup is not God. Spiritually broken and guilt-ridden, Suttree is yearning for some form of redemption, some answer to his life that his past cannot help him with. Shortly after this visit to the church, Suttree goes in search of answers in the present, detaching himself from his life in Knoxville and journeys on a desperate spiritual pilgrimage. He takes a bus to Gatlingburg in late October and hikes into the surrounding Smoky Mountains. This is a different journey than John Grady’s. Although the novel is not explicit, from Suttree’s drunken visit to the church and his wandering of the streets it can be surmised that the guilt, shame, anger and emptiness Suttree feels have intensified to a fever pitch and he is looking for a reprieve, whether it be something that orders his life or something that completely unravels it; Gary Adelman describes Suttree’s mentality well in *Sorrow’s Rigging*, writing that Suttree goes into the mountains “desiring pain, cleansing pain, mortification, to be alone, lost . . . purged of memories, purged of identity” (32). What Suttree needs at this point in the novel is complex and difficult to describe; it could be one or all of the desires Adelman lists. A cleansing and purging of himself is indeed a spiritual and existential desire, and the fact that he leaves human society and treks into the wilderness of the natural world suggests that he is instinctively drawn to it or believes nature will play an essential part in the cleansing process. Suttree’s quest into the mountains is a gradual one, with his perspective shifting as he leaves first the roads and then the trails, making his way deeper into the heart of the mountains. At first he attempts to catch fish to no avail and builds fires where he can, but soon he is starving, eating roots, mushrooms, and whatever he can find. In his starvation, however, his senses begin to awaken. He is surprised to find some small flowers in the woods and “fell into silent studies over the delicate loomwork in the moss” (284). He is beginning to notice the fine, beautiful details in nature—even the fungi on rotting logs—and meditate on them. Thomas Young writes that Suttree “purposefully courts the primitive realms of being” and that the time spent alone puts him in “a state of visionary power that allows him to see the world as it is” (78). Suttree’s state is a shift in perception similar to the ability of the magician that Abram describes, allowing him to experience the natural world outside of societal and human constructs and in a less subjective (albeit not totally objective) light. Despite his newfound reverence for nature, Suttree does not yet feel connected to it. At first he feels alone in the mountains, especially at night: “The cold indifferent dark, the blind stars beaded on their tracks and mitered satellites and geared and pinioned planets all reeling through the black of space” (284). This is the description of an aloof, uncaring world with nothing sentient behind it. The satellites and mechanical word choices of “geared” and “pinioned” make this a world tainted by man and his influence. This bleak outlook on the world does not last, however. After Suttree goes days without food and wrapped only in a shoddy blanket, he stops by a stream for a drink and then slumps down: He looked at a world of incredible loveliness. Old distaff Celt’s blood in some back chamber of his brain moved him to discourse with the birches, with the oaks. A cool green fire kept breaking in the woods and he could hear the footsteps of the dead. Everything had fallen from him. He scarce could tell where his being ended or the world began nor did he care. (286) This is a significant experience for Suttree, one that will prove to be a turning point for his relationship not only with the world around him, but also with his own guilt and shame. Blood again plays a key role in the bridging of the natural and human world, moving Suttree to an even deeper state of visionary power. The Celt blood from his mother’s side is credited with invoking this experience (possibly a reference to Celtic tree worship), connecting Suttree to a tradition ancient and lost, one that—as Abram puts it—still found spirituality and “alien zones of intelligence” within nature. The spiritual, freeing, and whimsical act of speaking with trees comes from his mother and strongly contrasts with the cold, logical, and orderly disposition of Suttree’s father. Suttree thought he was rebelliously embracing his mother’s heritage by being a poor fisherman, but now her true heritage has overcome him, allowing him to connect with the reality of the natural world the way his ancestors did. Divisions dissolve: the division between man and tree; the living and the dead; between Suttree and the world. He lies on the ground, “the earth’s core sucking his bones,” the world pulling him to itself but at the same time giving him the sensation of “falling outward through blue and windy space” (286). Everything in nature has become heightened and more experiential; the woods “looked too green for the season,” and later he envisions a war happening during a storm, with the lightning and smoke “more palpable than wortled bone or plate or pauldron shelled with rot” (287). However, his senses are also confused and indescribable—surely starvation and exposure are at work, but at the same time, Suttree seems insightful throughout this experience, even being able to “feel the oilless turning of the earth beneath him” (286). The word “oilless” is an odd choice here; one would think that the turning of the earth ought be described as “oiled,” fluid and consistent. However, a possible definition may be “not requiring oil,” separating the earth from things mechanical and manmade, which often require oil as lubricant to work. Suttree’s sense of the world turning not only proves how enveloped and in tune he is with the natural world at this point, but also reveals that there is not a “mechanism” operating the world, at least not in the traditional sense of the word. The world turns and it seems it will turn forever, and while the reasons behind it are a mystery, the effect can be felt. The eternal mystery of the ever-turning world is emphasized even more when contrasted with the image of impermanence that Suttree comes upon later that evening: a children’s cemetery next to the ruins of a church. “The stone footings of a church nearby was all the church there was,” writes McCarthy (286). After the previous church scene, it is likely that in this passage “church” signifies “the Church,” and all organized religion, for that matter. The stone footings aren’t just all of the church building there was, it is all of the Church there was; for Suttree, the Catholic Church is not “God’s house,” but an empty façade that, like everything manmade, breaks down and wears away in time. This idea is strengthened by Suttree walking among the children’s graves, “the naked headboards all but perished in the weathers of seasons past,” a precursor to the description of the dream John Grady has with the horses walking among the worn graves of men (286). The lives and works of men—even the revealed theology and work related to the supernatural—all fade away, while the spirituality of nature lasts and endures. As Suttree leaves this scene, the storm that has followed him begins to break and “a drop of rain sang on a stone. Bell loud in the wild silence” (286). Just as the trees “speak,” the rain “sings.” It is not the church bell that tolls for these children anymore, but the “bell” of nature that will forever remember them, much like the horses visiting the graves of men. Although the novel is not explicit, this scene affirms Suttree’s negative views and doubt of organized religion, suggesting that the guilt forced upon him during his childhood was indeed unfounded and that spirituality and truth resides elsewhere, yet everywhere: in the world around him. Along with addressing Suttree’s guilt associated with religion, Suttree’s experience in the wilderness of the natural world also makes him face the existential crisis associated with the death of his twin that he has dealt with all his life. After the children’s graveyard scene, Suttree’s trek in the mountains takes a strange turn, with Suttree seeing extraordinary apparitions including monks, warring armies, and a grotesque carnival. However, the most important apparition is “some othersuttree” that he begins to sense going before him, and fears that if they ended up meeting he would not be “mended or made whole,” but “set mindless to dodder drooling with his ghostly clone” (287). This is not simply a part of Suttree himself, but an eerie doppleganger that clearly represents his dead older brother. The power relationship between Suttree and the doppleganger and Suttree and his dead twin are the same; in both relationships Suttree is the “younger” or the “one behind.” Suttree is also the one without power in the relationship; the doppleganger is the one moving and allowing Suttree to avoid meeting him and making him go mad and, although it is Suttree that kicks his twin to death, the twin now holds power over Suttree in ways unimaginable, through insurmountable guilt, existential crisis, and psychological anguish. Although this doppleganger is an apparition, Suttree’s psyche is manifesting a psychological reality into the natural world, and in doing so reveals a truth that Suttree knows yet has not been able to confront and overcome on a rational, logical level. By manifesting his twin into the natural world Suttree is able to see his problem in a different perspective and to get it out of himself and separate it from himself which, as this scene proves, is extremely important. This is a part of him that needs to be separate; otherwise, he will continue to be driven into madness. Only through isolating himself in the wilderness of the natural world was this possible. The natural world also provides another meaningful vision to Suttree, albeit one less personal. After a storm moves off, he sees a grotesque carnival of trolls and fantasy creatures parading in the rain with an assortment of imprisoned or killed mythical creatures: a caged wivern, skewered chimeras and cacodemons, and “other alchemical game” (287). This vision seems fantastic and nonsensical—and it certainly is—but although Suttree watches it go by “with a half grin of wry doubt,” there is a meaning to the carnival that connects with the spirituality of the natural world and the commodification of nature. The trolls’ casual killing and parading of animals that the average human would consider extraordinary is a satire of Knoxville and, more tangibly, the antics of Harrogate; the killing of dozens and dozens of bats for the sake of coin should hold the same weight as the skewered chimera. Humanity has lost reverence and awe for the natural world, and in that respect, this ghastly carnival is not so fantastical after all; it actually resembles a Mexican carnival McCarthy will later describe in *The Crossing*, in which the shewolf is killed. Just as the eternity of the natural world was heightened by contrasting it with the proceeding scene of the children’s graveyard, the meaning of the carnival is heightened by comparing it with the scene that follows, in which Suttree passes a hunter in a tree stand. The hunter is hunting out of season with a crossbow, a weapon likely illegal to hunt with at all. The hunter waiting in his tree stand to poach deer with an overpowered bow shows little reverence for the animal, and his commodification is made clear when he tells Suttree that the crossbow has “killed more meat than you could bear [emphasis added],” as opposed to “more deer” or “more animals” (289). The hunter also serves as a transition from the mystic natural world that Suttree is leaving to the town that Suttree is about to enter. Suttree thinks that this hunter is just like the carnival: an apparition. Comically, the hunter is not sure what to make of the starved, haggard, half-naked Suttree, either: “What are you?” he asks, to which Suttree laughs and asks his own question: “Are you real?” (288). These questions of identity and reality are the questions that led Suttree into the mountains in the first place, and although they have not been answered, his perspective has been altered as he comes down from the mountain. Self-conceptualization and reality continue to be themes of McCarthy’s novels and are directly linked to first-hand exposure to the natural world. This change in perspective is even more apparent when Suttree finally reaches the town and returns to the things of civilization. What should be the familiar are foreign and unintelligible to him, especially writing. The newspaper is “a rash of incomprehensible events” (292), and the words in a copy of the Book of Mormon he reads “swam off the page eerily” (294). With his perspective still shifted from his time in the mountains, his “sense” for reading and writing has been lost, temporarily transferred to the “language” of the trees and the wilderness. In addition, he comprehends images of nature within society much differently than before. Upon entering a diner he hears “the dull tocking of applewood clockworks,” and he sees a “blackened trout” on a board and an old “naked leather squirrel” taxidermy with “vitreous eyebulbs,” saying that both of these animals “knew not” (292). These are natural elements—both plant and animal—commodified and altered: the tree for function, the trout likely for pride and posterity, and the squirrel for curiosity. All of them are a hybrid of animal and man, and Suttree understands these things as grotesque, and his pointing out that the animals “knew not” insinuates that these animals are nothing now, or gave no consent in their current fates. “From this perspective all nature seems misshapen,” Young states, “reduced to incomprehensible relics by the human appropriation of it” (79). Society’s views of the natural world are misshapen, but Suttree could not see this from his perspective within society; it is only after venturing out, diminishing himself, and experiencing the mystery of nature that he is able to not only see nature for what it is, but also to see how irreverent and disassociated mankind has become with the natural world, symbolized by these human-appropriated “relics.” Suttree’s change in perspective subtly remains throughout the rest of the novel, with him unable to find his way in human society but also struggling to connect with nature again. This change in perspective is the seed of a psychological transformation, but it even has physical ramifications, ramifications not lost on Suttree. At the diner, he cannot eat the food; it gums up in his mouth and he cannot taste anything. “Is there something wrong with me?” he demands, then mutters, “The imago does not eat” (292). “Imago” could either refer to the image of God or the final stage of an insect’s development. The theological definition implies that Suttree either sees himself as a thing false and artificial, unable to perform the natural act of eating and sustaining itself, or that it is as if he has had a supernatural transformation that has made food unnecessary; this is a fitting revelation after a time spent in the reality of the natural world. The biological definition of “imago” acknowledges that Suttree has developed somehow into another stage of being, as if his revelation has led to a psychological and spiritual transfiguration. Despite this acknowledgement, Suttree struggles to live up to such a state throughout the rest of the novel. He eventually reenters human society, joining a family in a musseling business that fails, and having a foray with a prostitute that ends very badly. He fears that these interactions in society have pushed him away from what he found in the wilderness of the Smoky Mountains. At the beginning of his musseling job, he sleeps out in the woods and wakes feeling “alien and tainted” camped out in the wilderness: “As if the city had marked him. So that no eldritch daemon would speak him secrets in this wood” (316). This is an important statement because Suttree not only admits to feeling a duality between the city and nature, but also that he wants to experience that mystical spirituality of the natural world, to again hear the secrets of the wood. Unfortunately, Suttree does not realize that the work he is about to do will be the opposite of communion with nature. In fact, what he experiences is the worst side of commodification and human labor; the camp he works at is incredibly impoverished, the work is hard and unrewarding, and Reese’s management is comically abysmal. One night after a few weeks of work, Reese takes Suttree into town to drink away the little money that they have made. It would be expected that Suttree, a man known to appreciate alcohol, would have at least enjoyed himself that night. Instead, after stumbling into his camp he lies down, too tired to even bathe. Before falling asleep, he looks at the ground he is sleeping on: “My life is ghastly, he told the grass” (348). Suttree is aware that he has fallen into a terrible existence, and looks not to another human being for solace, but to the grass, to nature itself. If his mark prevents the daemon for speaking to him, perhaps his initiation of the conversation—especially in the form of a confession—will be at least a step in the right direction to ridding himself of the city mark. Of course, this mark is really an invention of Suttree’s; it is not an external force alienating him from nature, but his slipping back into his old frame of mind before being able to reconcile the perspective and true vision he experienced in the mountains with the workings of human society that he has returned to. Fortunately Suttree does not remain in this state of irreconcilable limbo; by the end of the novel he has not only overcome much of the guilt and shame from his past but has found an equilibrium between the human world and the natural world. This is all brought about by his return to the houseboat, his own space in the world. The journey Suttree goes on turns out to be a circular one, and it is not until he arrives home and is alone in his riverside house that the experiences he has had come to fruition. He repairs the houseboat, which he finds vandalized and pillaged, and in returning order to his home (or the place he can most call home) he appears to order his thoughts as well. After setting his fishing lines, he eats supper and sits “listening to the river, the newspaper open across his lap, and an uneasy peace came over him, a strange kind of contentment” (413). Here, a symbol of nature (the river) and man (the newspaper) comingle, but it produces a good feeling for Suttree, and puts him in a state of mind to come to terms with reality. He leans back in his chair, a calm and leisurely posture, and starts a question-and-answer session with the orb of lamplight on the ceiling, a stand-in for the world, and possibly God. It is a conversation about death—a subject that has haunted Suttree—and about belief. When he asks himself if he repents of anything, he says he repents for speaking “with bitterness” about his life and for saying he would rally against the “monstrous facelessness” of oblivion and “stand a stone in the very void” so others “would read my name” (414). He repents of trying to fight against the world, to understand it and overcome the immensity of the universe and be remembered for doing so. His journey into the wilderness has proven to him that there is more to the void; there is a mystical spirituality in the natural world, and although the universe is an immense, unfathomable vacuum, it is a reality that can be experienced. The journey also revealed to him that human history and society are temporal compared to nature, and that any headstone erected for him in “the void” would wear and disappear, just like the stones of the children’s graveyard and the stones the horses walk amongst. He has come to terms with these facts, and in so doing, has reconciled himself: “He leaned and blew away the flame, his double, the image overhead” (414). The “othersuttree”—whether it is his twin brother, or the duality that manifested in his mind due to guilt and shame—is gone, finally overcome as Suttree comes to terms with the world. In addition to reconciling with himself and the world, Suttree takes another journey of self-discovery, a more permanent one that ends the novel. After a dead man found in his houseboat is mistaken for Suttree—a strange event that not only conveniently allows Suttree to slip away, but also symbolizes the “death” of his old self—Suttree leaves Knoxville. As he walks down the streets for the last time, “he felt everything fall away from him,” much the way his clothes began to fall from him during his journey into the Smoky Mountains: “There was nothing left of him to shed. It was all gone. No trail, no track” (468). He has “shed” everything to again reach the “imago” stage he experienced in the mountains, but this time it was not an involuntary metamorphosis achieved through starvation and isolation. If the city had left a mark on Suttree, it was gone now, along with everything else he has rid himself of: the sin, the guilt, and the shame. Suttree has also reconciled himself with the city, just as he has with the natural world. As he waits on the side of the road to hitchhike, a construction gang works on the other side of the road, and a young boy with a pail of water offers some to each of the workers. The act is a clear symbol of Communion; McCarthy writes that the workers’ “hands come up from below the rim of the pit in parched supplication” (470). The boy approaches Suttree of his own volition and offers Suttree the dipper, “bright and dripping,” with “water beading coldly on the tin” and drops steaming as they hit the road (470). This is an icy cold cup of water, similar to the cup of water Suttree drinks before his strongest experience in the mountains, water that “lay in his stomach as cold as when he drank it” (286). This water is truth and life: earlier Suttree concludes, “The color of this life is water” (415). Suttree takes and drinks, and then a car is waiting for him, stopped without Suttree’s bidding: similar to the boy approaching Suttree voluntarily. Suttree didn’t even lift a hand for it to stop for him; it is as if fate or something supernatural is watching over him, unfolding this journey for Suttree. It is clear that Suttree is leaving behind the city, the “sad purlieus of the dead immured with the bones of friends and forbearers,” possibly for the less-urbanized west (471). Seeking out the wilderness of the west also coincides with everything that Suttree has experienced in the natural world and what he longs to be a part of. However, where Suttree is going and what he will find there is ultimately a mystery. Young speculates that “Suttree clearly has learned the precept that the outer world is beautiful and real. Whether this can truly be more than precept for him, however, must remain in doubt” (91). While Young’s doubt is certainly understandable during most of the second half of the novel, the ending seems rather hopeful in this regard. It is true that Suttree’s powerful perception wanes after his Smoky Mountains trek, but in the end he learns to accept himself and the world for what it is, a result certainly driven by his experiences and visions in the natural world. This is emphasized by the hound that comes out from the woods and sniffs the spot where Suttree stood, just missing him; the huntsman and his hounds are a symbol of death, and Suttree has just literally escaped death and reconciled himself with the idea of death and the death of his twin. His spiritual experience in the natural world has allowed him to shed his past preoccupation with death for good, to live in the “world of incredible loveliness,” in the psychological sense and—more than likely—the literal sense. The Redemptive Truth of Nature The radical impact nature has on the characters and the plot of McCarthy’s fiction is why examining its role within the novels is essential to understanding the consistent yet ever-evolving philosophical and spiritual questions of his texts and the relationship between man and his “other,” nature. John Grady and Suttree have contrasting—yet complementary—experiences with the natural world. In certain respects, these two protagonists are distinctively different. John Grady is a young, rather innocent youth, especially compared to the baggage the older and jaded Suttree carries with him. John Grady is initially much closer to the natural world, and his abilities and history with horses provide him with a connection to nature; he is already acclimated to it, primed to experience it. Suttree, on the other hand, has no such connection, and his journey towards mystically experiencing nature is a longer, more complicated one. However, what both protagonists do share is a feeling of alienation and a desire for truth—both a glimpse at the “truth of the universe” and the ability stand for what is true and not be complacent with anything else. Despite their different backgrounds and journeys, the natural world helps them both get closer to a true, experiential spirituality. There are several other characters who have similar experiences with and insight into the natural world, and all their journeys fall somewhere between John Grady’s and Suttree’s. Billy Parham’s journey with the shewolf he captures in The Crossing is an example of naïve innocence that allows for insight and a reverence for the natural world. He makes a conscious decision to help the pregnant wolf and return it to “the mountains”—the human-free wilderness—and is asked several times to sell the wolf, but refuses. The shewolf serves as an image of the savage beauty of the natural world, and it is this being isolated with this beauty that causes Billy to decide to release the wolf to the natural world instead of selling her. Unfortunately, he must shoot the wolf out of mercy, as she is painfully and brutally attacked by dogs for the entertainment of a carnival circus. Commodification will take more from him, as he returns home to find his parents murdered for their horses. Billy’s second crossing of the border is again motivated by “doing right” for animals, to retrieve the horses. Although Billy never reaches as personal a connection with the natural world as John Grady or Suttree, he gathers a respect and pity for animals and attempts to right the wrongs of his fellow men. Arthur Ownby is another character that takes on the stewardship role and has a great respect for the natural world. He is the orchard keeper, but also the keeper of a time that is expiring or has expired, before urbanization and industrialization clashed with the natural world. Steven Frye describes this time as “an old order, a time when survival, human happiness, even spiritual sustenance came from cultivating a synergistic relationship with the untamed wilderness” (24). Arthur is the forbearer of what the protagonists of McCarthy’s later novels must rediscover through direct experience with the mystery of the natural world. Arthur relates a past experience with panthers, an animal that he endows with a mystic and supernatural otherness: “They’s painters [panthers] and they’s painters. Some of em is jest that, and then others is right uncommon. That old she-painter, she never left a track one. She wadn’t no common kind of painter” (157). Although this could be discredited as an old man telling tales, the general uneasiness of the men in the town when they mistake the sound of an owl for a panther is telling. Arthur teases them, his personal experience enough to know that it is an owl. The natural world still holds mystery and secrets, regardless of man’s inability to realize it consciously, and this mystery is terrifying and dangerous to those that do not understand it for what it is—a mystery. Arthur embraces nature for its mystery and spirituality, and although he suffers greatly for it, the passing on of his insight to John Rattner—exemplified in Rattner’s attempt to get back the dead hawk he sold to the county—not only makes his suffering for aught, but also sets the stage for the experiential insight and suffering that many of McCarthy’s protagonists will experience in the novels following *The Orchard Keeper*. Like Arthur, there are several secondary characters that are close to the natural world and experience it for what it is. Suttree’s friend Michael, “the Indian,” is one with nature in a way Suttree finds difficult to be, symbolized by the bait Michael uses to catch enormous fish that Suttree cannot stand because of its strong odor (222). Michael lives on a hill in a cave with “a natural terrace,” a home in the very heart of the natural world (239). After he kills a turtle to prepare for dinner, Michael is described as swinging the turtle before him “like a censer,” an image that gives both Michael and his relationship with the natural world a spiritual connotation (234). Later he “crouched like an icon and began to ladle the stew into his jaws”—“icon” is another religious and spiritual image, and the use of “jaws” as opposed to “mouth” is more animalistic than human (240). This is also when he makes the true prophesy that Suttree “wont stay” on the river, making Michael a mystic of the natural world (240). Don Arnulfo is another such mystic, whose life of trapping wolves has made him only respect the wolf and view it as something otherworldly, separate from humans. Although *The Crossing* does not divulge much about Don Arnulfo’s past, the fact that he tells Billy that he “should find the place where acts of God and those of man are of a piece” and has such insight into the differences between nature and man suggests experiential knowledge of the divine and of nature (47). And, like Arthur, Don Arnulfo’s time is past and he is being forgotten: “No one comes to see him,” his caretaker says (47). The industrialized world moves on and leaves men like Don Arnulfo behind, bestowing wisdom and insight on a single member of the next generation. Although the “time” for many of these characters is past as urbanized society loses reverence and connection with the natural world, nature is still there to be experienced—nature is never spent. There is freshness in “deep down things,” things eternal and otherworldly that cannot be completely understood. Despite the coming urbanization of America—ironically and iconically symbolized by the nuclear flash in *The Crossing*—and man’s ability to discern mystery and awe in the natural world as “the last lights off the black West” go, there is something larger than man, animal, or plant at work. Whether McCarthy’s fiction follows parallel with the rest of Hopkins’ poem—that behind the world is the Holy Ghost raising the sun again, issuing in the rejuvenation of nature with “ah! Bright wings”—is an issue that is not answerable (13-14). McCarthy’s novels avoid naming the force behind nature and its mystical “otherworld,” so whether it is the Christian God or not is a mystery; even if it is, the term “Christian God” cannot completely describe or encapsulate this force. Over and over again, McCarthy hints at the mystical otherworld of blood and death, but does not define it; in fact, he often discredits preachers, priests, and laymen that claim with a definite level of exactitude to understand how the spiritual realm operates. However, while this allows for a multitude of possibilities as to what has structured the world, this does not discredit the idea of the Christian God being behind the world as a one of those possibilities. As there are many discredited Christian clergy, so are there many mystical Christian “clergy”—often unofficial, or ex-clergy—that are portrayed as wise and knowing, such as Tobin the ex-priest, the “church custodian” Billy meets in *The Crossing*, and the goatman in *Suttree*. Don Arnulfo and the ragman Suttree befriends also believe in God, albeit untraditionally; the ragman says that although he “always figured” there was a God, he “just never did like him” (147). Even if it is the Holy Ghost that breaths life into nature, that death is inevitable is a fact that plagues the characters in the McCarthy universe, regardless of their experiences with the natural world and tapping into the mystical spirituality of it. Regardless, the natural world is still endowed with a spiritual truth in McCarthy novels, and it is a spiritual truth that can be experienced and learned from by man. Several critics, including Jay Ellis and Edwin Arnold, agree that despite the fact of death that is explored in McCarthy’s work, McCarthy cannot be read as a fundamental nihilist because of the insight that his protagonists acquire through experiencing the natural world and the rare charity of other people. Indeed, when the “otherworld” that is charged with blood and death is glimpsed at by man, it is terrifying and awful in the archaic sense of the word, and death does not seem something to be feared but instead a truth that is powerful and mysterious. In addition, this glimpse is usually paired with a glimpse into the beauty of the world—such as it is with Suttree and his “world of incredible loveliness”—that is so immediately transformational it is as if scales have fallen from the eyes of the man. It is religious in the sense that it is something supernatural that is revealed, and this revelation demands to be acknowledged and enacts change in the individual’s actions or thinking. Although following this revelation often translates into following ideals that lead to imprisonment or death—as is the case with Arthur Ownby, John Grady, and Billy—standing up for these ideals, for the truth found in the natural world, is always described as the correct and heroic thing to do. The nature-endorsing mentality is passed down from generation to generation, from novel to novel, amidst a society of ever-increasing urbanization. The commodification that comes with urbanization is dangerous not only to the natural world but to those without power and wealth, as exemplified by the demolition of the slums in *Suttree* and the scalping and raiding of innocent Native Americans in *Blood Meridian*. The protagonists generally attempt to fight against these forces, or show empathy to the plights of those without power; in the case of Suttree, he gives up a life of wealth to live among the poor and homeless, and the judge labels the kid as mutinous because he reserved “clemency for the heathen” and did not fall in line with the judge’s wishes and worldview (312). Those characters that experience the reality of nature rebel against the commodification and egotistical worldviews of the societies and company they find themselves in. Unfortunately, this rebellion usually leads to suffering and, at times, death for standing up for ideals and morals no longer held sacred. Nature is both reality and mystery to McCarthy, a question that cannot be answered without assuming too much or oversimplifying it, which only results in a pseudo-reality: a lie. From this, more questions are brought about by McCarthy’s work: How mankind can live and remain grounded in the reality of nature that one cannot fathom, and why would man even choose the unanswerable spiritual reality of nature over a smaller, more comfortable worldview—alternatively, how can mankind be content to live in the Garden with the mystery of the forbidden fruit left untasted, undetermined? Steven Frye proposes that the word “mystery” expresses McCarthy’s vision of the human condition as well, with “his renderings of death, fear of cosmic annihilation, and even the confusion that emerges from the diversity of the twentieth-century intellectual climate” (12). The mystery of nature makes the human condition a mystery as well, with death and the immensity of the cosmos the great unknowns behind the “gatelamps” of the natural world, and mankind’s role in all this unknowable on this plane. Frye also articulates well the collision of worldviews apparent in the texts as commoditization and urbanization pull men away from the reality and spirituality of nature and allow them to construct their own realities that ultimately lead to complacent anthropocentrism. Despite its frightening immensity, nature still holds promise in the McCarthy universe for those willing to experience its reality. Without the symbolic nature of language confining reality, man is exposed to the unfathomable mystery of the world but is always driven towards enlightenment and an experiential understanding of the mysterious order of things. Nature is a reality in which the immensity of gods may be fully realized and undistorted, and the spirituality of animals can be rediscovered and intuitively held sacred. As Hopkins beautifully illustrates, nature is the never-ending source of truth and spirituality, charged with a supernatural power beyond the smudging power of mankind and its trade. If God exists, then surely He exists in the realm beyond nature, in the terrifying and awesome vastness that man can only glimpse in the loveliness of a glade, the power of a lightening strike, and the deep, dark eyes of a wolf. Bibliography Spencer, William. “On the Range of Styles in *All the Pretty Horses*.“ *Publications of the*
UV VISIBLE SPECTROSCOPY Yogita B Ade¹ Ramkrashna S Chavan² Rushikesh S Garad³ DR. Santosh Jain⁴ Akhil A Students¹ Student ² Guide³ Principal⁴ Student⁵ ADITYA INSTITUTE OF PHARMACEUTICA BEED DR. BABASAHEB AMBEDKAR TECHNOLOGICAL EDUCATION, LONERA Abstract: Ultraviolet and visible (UV-Vis) absorption spectroscopy is the measurement of the attenuation of a beam of light after it passes through a sample or after reflection from a sample surface. This article uses the term UV-Vis spectroscopy to include a variety of absorption, transmittance, and reflectance measurements in the ultraviolet (UV), visible, and near-infrared (NIR) spectral regions. These measurements can be at a single wavelength or over an extended spectral range. This article provides an overview of the technique and does not attempt to provide a comprehensive review of the many applications of UV-Vis spectroscopy in materials research. In this regard, many of the references were chosen to illustrate the diversity of applications rather than to comprehensively survey the uses of UV-Vis spectroscopy. Rapid and easy analytical methods are needed due to increasing number of multicomponent formulation bio therapeutic product and sample of complex matrix Number of ultraviolet spectrophotometer method use for these purposes. Ultraviolet and visible absorption Spectroscopy is the measurements of the attenuation of a beam of light after reflection from a sample surface. Keywords: Ultraviolet-Visible-near Infrared (UV-VIS-NIR), Ultraviolet-Visible (UV-VIS), Light emitting diode (LED), Transmittance 1) INTRODUCTION: What is UV-Vis spectroscopy? UV-Vis spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample. Ultraviolet-visible (UV-visible) spectrophotometry is primarily a quantitative analytical technique concerned with the absorption of near-UV (180-390 nm) or visible (390-780 nm) radiation by chemical species in solution. Spectroscopy in the ultraviolet (UV), visible (Vis) and near infrared (NIR) region of the electromagnetic spectrum. The Principle of UV-Visible Spectroscopy is based on the absorption of ultraviolet light or visible light by chemical compounds, which results in the production of distinct spectra. Spectroscopy is based on the interaction between light and matter. Spectroscopic investigations of solutions, gas phase crystals usually take place in transmission, but it is very difficult to obtain transparent films of powders (e.g., heterogeneous catalysts), making transmission experiments almost impossible. Alternatively, diffuse reflected light can be collected and this technique has been named diffuse reflectance spectroscopy (DRS) [2]. One of the advantages of DRS is that the obtained information is directly chemical in nature since outer shell electrons of the ions are probed. This provides information about state and coordination environment of ions in catalytic solids. The same holds for the nature species and different hydrocarbon species can be investigated. Furthermore, DRS is quantitative and can be in-situ conditions. The main disadvantage of the technique is that DRS spectra are complex, and usually encompass several broad and overlapping bands. In order to spectral analysis, techniques need to. This is especially important for in-situ time-re-solved DRS studies because of the extensive to be handled. This chapter starts with a short overview of the principles of DRS. Theoretical as well as practical aspects will be discussed. The next section focuses on three examples in order to illustrate the potential and limitations of in situ NIR spectroscopy. UV visible spectroscopy is the classical and the most reliable technique for qualitative and quantitative analysis of organic compounds visible spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample. 2) **PRINCIPLE OF UV VISIBLE SPECTROSCOPY:** When radiation in the wavelength range 10 to 780 nm passes through the solution of the compound electron get excited from lower energy level to higher energy level during this process it absorption some energy to the solution. The difference between the energies of ground state and higher excited state is called as delta E and this energy is equal to the amount of UV radiation absorb by the molecule. UV visible spectroscopy is the most important techniques for qualitative or quantitative analysis it is also called as electronic spectroscopy. The Principle of UV-Visible Spectroscopy is based on the absorption of ultraviolet light or visible light by chemical compounds, which results in the production of distinct spectra. Spectroscopy is based on the interaction between light and matter. When the matter absorbs the light, it undergoes excitation and de-excitation, resulting in the production of a spectrum. When matter absorbs ultraviolet radiation, the electrons present in it undergo excitation. This causes them to jump from a ground state (an energy state with a relatively small amount of energy associated with it) to an excited state (an energy state with a relatively large amount of energy associated with it). It is important to note that the difference in the energies of the ground state and the excited state of the electron is always equal to the amount of ultraviolet radiation or visible radiation absorbed by it. Spectrophotometry is a procedure for determining how much light is reflected by a chemical material by measuring the strength of light as a light beam travels through the sample solution. The fundamental theory is that light is absorbed or emitted over a certain wavelength spectrum by each compound. Spectroscopy is known as the measurement and interpretation of electromagnetic radiation emitted or absorbed, when ions, atoms or molecules of a sample move from one energy state to another energy state. Ultraviolet-Visible spectroscopy UV-Vis spectroscopy is a type of absorption spectroscopy, which utilizes the radiation in the UV range and adjacent visible range of the electromagnetic radiation spectrum. The absorption wavelength mainly ranges from 100-700 nm 3) **ELECTRONIC TRANSITION:** The absorption of ultraviolet or visible radiation generally results from excitation of bonding electron as a consequence, the wavelength of absorption peaks can be correlated with the types of bonds that exist in the species under study. UV visible spectroscopy involve transition of electrons to from lower energy level to higher energy level. When any molecule absorb UV radiation their outermost electrons absorb the radiation and get excited to higher energy level. - **THREE TYPES OF ELECTRON**: 1. **π ELECTRON** 2. **SIGMA ELECTRON** 3. **N-ELECTRON** 1. **π ELECTRON**: Compounds having double and triple bonds undergo this type of transition electron. Example -- Benzene. The bonding molecular orbital component of a pi bond. The orbital of ethylene's carbon-carbon pi bond has two orbital lobes, one above the plane of the atoms, and another below the plane. This is a bonding molecular orbital. The plane containing the atoms is also the pi orbital's one node. 2. **SIGMA ELECTRON**: These electrons present in all single bonded compounds. example-methane, propane. Sigma bonds are the strongest type of covalent chemical bond. They are formed head-on overlapping between atomic orbitals. Sigma bonding is most simply defined for diatomic molecules using the language and tools of geometry groups. 3. **N ELECTRON** (non bonding electron):- These electrons are not involve in bond formation. They are absolutely free or easily available. Example nitrogen oxygen sulfur. Non-bonding orbitals are often designated by the letter n in molecular orbital diagrams and electron transition notations. FOUR TYPES OF ELECTRON TRANSITION :- 1) SIGMA TO SIGMA STAR 2) N TO SIGMA STAR 3) \( \pi \) TO \( \pi \) STAR 4) N TO \( \pi \) STAR 1. SIGMA TO SIGMA STAR :- Saturated compounds undergo this type of transition. Example - methane, propane, ethane. Single bonded compounds. An electronic in a bonding Sigma orbital of a molecule is excited to the corresponding anti- bonding orbital by the absorption of radiation. In ethane, electrons of C-C bond appear to be involved. Because the strength of the C-C bond is less than that of the C-H bond, less energy is required for excitation thus the absorption peaks occurs at a longer wavelengths. 2. N- TO SIGMA STAR :- This type of transition involves compound having at least one hetero atom with lone pair of electron. It is less than sigma to sigma star N to sigma star transition (n→→ 0*) involves saturated compounds with one hetero atom like oxygen, nitrogen, fluorine, chlorine, etc. Normally, saturated halides, alcohols, ethers, aldehyde, ketones, and amines participate in this type of transition. Absorption maxima for the formation of the n. sigma star state tend to shift to shorter wavelengths in the presence of polar solvents such as water or ethanol. 3. N- TO \( \pi \) STAR :- Compounds having double and triple bonds undergo this type of transition. All aromatic compounds. Example - Benzene. These transitions involve moving an electron from a bonding a orbital to an antibonding ** orbital. They tend to have molar absorptivity on the order of 10,000 and undergo a red shift with solvent interactions (a shift to lower energy and longer wavelengths). 4. N TO \( \pi \) STAR :- It involves very less energy as compare to other transition. Compounds having double and triple bonds at least one hetero atom undergo this type of transition. The "n" electrons (or the nonbonding electrons) are the ones located on the oxygen of the carbonyl group of tetraphenylpentadienone. 4) CHROMOPHORE AND AUXOCROME : CHROMOPHORE :- This term used for any group which gives colour to the compound any group which absorb UV and visible radiation and shows pic in this spectrum is called as chromophore. Both organic and inorganic molecules may exhibit absorption and emission of UV-VIS radiation. Molecular groups that absorb visible or UV light are called chromophores. A chromophore group is a functional group, not conjugated with another group, which exhibit a characteristic absorption spectrum in the ultraviolet or visible region. The chromophore is a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum. Visible light that hits the chromophore can thus be absorbed by exciting an electron from its ground state into an excited state. A chromophore is the section of a molecule that causes us to see color. The chromophore portion of the molecule will have alternating double bonds, or conjugated double bonds. For example, beta-carotene, the molecule responsible for the color in carrots, has many double bonds. AUXOCROMES :- Any group which dose not act as chromophore but it's presence shift the absorption maxima towards higher wavelengths. The colour of molecules may be interested by the groups called as auxochromes which generally do not absorb significantly in the 200-800 nm region, but will affect the spectrum of the chromophore to which it is attached. The most important auxochromes groups are OH, NH2, CH3 and NO2 and their properties are acidic or basic. An auxochrome is a functional group of atoms with one or more lone pairs of electrons when attached to a chromophore, alters both the wavelength and intensity of absorption. Four Shifting of Chromophore :- 1) Bathochromic Shift Shifting of absorption maxima towards higher wavelengths due to addition of auxochromes groups is called as BATHOCROMIC shift and also called as red shift. Bathochromic shift is a change of spectral band position in the absorption, reflectance, transmittance, or emission spectrum of a molecule to a longer wavelength. Because the red color in the visible spectrum has a longer wavelength than most other colors, the effect is also commonly called a red shift. Due to the presence of an auxochrome, or solvent effect is called a bathochromic shift or red shift. For example, benzene shows $\lambda_{max}$ 256 nm and aniline shows $\lambda_{max}$ 280nm. 2) Hypsochromic Shift (Blue Shift) :- • Shifting of absorption maxima towards lower wavelengths due to removal of auxo group is called as hypsochromic shift and also called as blue shift. Hypochromic shift is a change of spectral band position in the absorption, reflectance, transmittance, or emission spectrum of a molecule to a shorter wavelength. Because the blue color in the visible spectrum has a shorter wavelength than most other colors, this effect is also commonly called a blue shift. • A hypsochromic shift is the shift of a peak or signal to shorter wavelength (higher energy). Also called a blue shift. For an absorption peak starting at $\lambda_{max} = 550$ nm, a shift to higher wavelength such as 650 nm is bathochromic, whereas a shift to lower wavelength such as 450 nm is hypsochromic. 3) Hyperchromic Shift: Shifting in the intensity of absorption maximum towards higher values of absorbance is called as hyperchromic shift. An increase in the absorption of ultraviolet light by a solution of DNA as these molecules are subjected to heat, alkaline conditions, etc. The shift is caused by the disruption of the hydrogen bonds of each DNA duplex to yield single-stranded structures. The phenomenon of UV absorbance increasing as DNA is denatured is known as the hyperchromic shift. The purine and pyrimidine bases in DNA strongly absorb ultraviolet light. Double-stranded DNA absorbs less strongly than denatured DNA due to the stacking interactions between the bases. 4) Hypochromic Shift:- Shift in the intensity of absorption maxima towards lower absorbance is called as hypochromatic shift. The Hypochromic Effect describes the decrease in the absorbance of ultraviolet light in a double stranded DNA compared to its single stranded counterpart. Compared to a single stranded DNA, a double stranded DNA consists of stacked bases that contribute to the stability and the hypochromicity of the DNA. 5) **BEER-LAMBERT LAW** Beers Lambert's law states that the absorption 'A' of a substance in solution is directly proportional to the concentration of the solution whereas Lambert's law states that each layer of equal thickness of an absorbing medium absorbs an equal fraction of the radiant energy. a) When passing through a transparent cuvette filled with sample solution, the light intensity is reduced proportional to the sample solution concentration. In other words, a higher concentrated sample solution will absorb more light. In addition the reduction the light intensity is also proportional to the length of the cuvette, a longer cuvette will be to a higher absorption of light. b) The Beer-Lambert law states that there is a linear relationship between the concentration and the absorbance of the solution, which enables the concentration of a solution to be calculated by measuring its absorbance. **FIG NO 2: BEER-LAMBERT LAW** ![Image of Beer-Lambert Law](image-url) **FORMULA** \[ A = a \cdot b \cdot e \] Where, - \( A \) = Absorbance - \( a \) = Molecular absorbing coefficient of the species. - \( b \) = Absorbing layer (path length) and - \( C \) = Molecular concentration of the absorbing species. 6) **SPECTROSCOPY** When an electromagnetic radiation is incident on a matter, phenomena like reflection, transmission, absorption are occurring. Spectroscopy is the study of interaction of electromagnetic... radiation with matter based on the Bohr-Einstein Frequency relationship $E = hv$ where $h$ is the proportionality constant called plank's constant and $V$ is frequency. Measurements of radiation intensity as a function of wavelengths is described by spectroscopy. **FIG NO 03: SPECTROSCOPY** Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Spectroscopy is used in physical and analytical chemistry to detect, determine, or quantify the molecular and/or structural composition sample. Each type of molecule and atom will reflect, absorb, or emit electromagnetic radiation in its own characteristic way. Spectroscopy is the study of the absorption and emission of light and other radiation by matter. It involves the splitting of light (or more precisely electromagnetic radiation) into its constituent wavelengths (a spectrum), which is done in much the same way as a prism splits light into a rainbow of colours. **SPECTRUM:** The spectrum is formed by electromagnetic waves and the wavelength is varies. Plural spectra spectra or spectrums.: a continuum of color formed when a beam of white light is dispersed (as by passage through a prism) so that its component wavelengths are arranged inorder. Autism is known as a "spectrum" disorder because there is wide variation in the type and severity of symptoms people experience. When a narrow beam of light is allowed to pass through a prism, grating it is dispersed into seven color from red, violets and band is called spectrum. **Fig.5 : Glass prism dispersion.** When white light is passed through a glass prism it splits into its spectrum of colours (in order violet, indigo, blue, green, yellow, orange and red) and this process of white light splitting intoits constituent colours is termed as dispersion. A word was first used scientifically in optics to describe the rainbow of colours invisible light after passing through a prism as scientific understanding of light advanced it came to apply to the entire electromagnetic spectrum. Colors A rainbow shows up as a spectrum of light: a band of familiar colors that include red, orange, yellow, green, blue, and violet. The name "Roy G. Biv" is an easy way to remember the colors of the rainbow, and the order in which they appear: red, orange, yellow, green, blue, indigo, and violet. This is the order of the wavelengths of visible light starting with red (the longest) and ending with violet (the shortest). It is also the order that colors appear in a rainbow! Rainbows appear when sunlight shines through water droplets suspended in the atmosphere. This is the order of the wavelengths of visible light starting with red (the longest) and ending with violet (the shortest). It is also the order that colors appear in a rainbow! Rainbows appear when sunlight shines through water droplets suspended in the atmosphere. The only difference between UV and IR light versus visible light is the wavelength. UV-VISIBLE SPECTROSCOPY:- Ultraviolet visible spectrum - can be generated when ultraviolet light and visible light (200-900) are absorbed by materials. The spectrum can be used to analyze the composition and the structure of the material. For a particular wavelength in the ultraviolet visible ranges, the absorption degree is proportional to the components of the material. UV spectroscopy or UV-visible spectrophotometry refers to absorption spectroscopy or reflectance spectroscopy in part of the ultraviolet and the full, adjacent visible regions of the electromagnetic spectrum. UV-visible (UV/Vis) spectroscopy is based on the absorption of the electromagnetic radiation in UV/Vis region, with the wavelength ranges of 200-400 nm, called 'ultraviolet spectroscopy, and 400-800 nm, called 'visible spectroscopy. UV-Vis spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample. This property is influenced by the sample composition, potentially providing information on what is in the sample and at what concentration. The Principle of UV-Visible Spectroscopy is based on the absorption of ultraviolet light or visible light by chemical compounds, which results in the production of distinct spectra. Spectroscopy is based on the interaction between light and matter. Ultraviolet-visible (UV-Vis) spectroscopy is a widely used technique in many areas of science ranging from bacterial culturing, drug identification and nucleic acid purity checks and quantitation, to quality control in the beverage industry and chemical research. UV spectroscopy or UV-visible spectrophotometry (UV-Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in part of the ultraviolet and the full, adjacent visible regions of the electromagnetic spectrum. 6) USES OF UV VISIBLE SPECTROSCOPY:- 1. It is used to study aromatic conjugation within molecules also used to differentiate whether the system is aromatic or aliphatic. 2. Used to major multiple bonds within compounds. 3. Used to differentiate alpha, beta, unsaturated compounds. 4. Ultraviolet-visible (UV-Vis) spectroscopy is a widely used technique in many areas of science ranging from bacterial culturing, drug identification and nucleic acid purity checks and quantitation, to quality control in the beverage industry and chemical research. 5. The advantage of an Ultraviolet Visible Light Spectrophotometer (UV-Vis spectrophotometer) is its quick analysis ability and easy to use. In astronomy research, an UV/Vis spectrophotometer helps the scientists to analyze the galaxies, neutron stars, and other celestial objects. 6. For semiconductors, UV-vis spectroscopy offers a convenient method of estimating the optical band gap, since it probes electronic transitions between the valence band and the conduction band. 7. While interaction with infrared light causes molecules to undergo vibrational transitions, the shorter wavelength, higher energy radiation in the UV (200-400 nm) and visible (400-700 nm) range of the electromagnetic spectrum causes many organic molecules to undergo electronic transitions. 8. What this means is that when the energy from UV or visible light is absorbed by a molecule, one of its electrons jumps from a lower energy to a higher energy molecular orbital. 9. UV-Vis spectrophotometers are used in almost every laboratory in the world due to their measurement versatility. This guide is a snapshot of the main spectrophotometer uses, with links to application notes by measurement technique and industry type. 10. UV/VIS spectroscopy is used for the quantitative determination of different substances. 8) INSTRUMENTATION : 1) SOURCES OF LIGHT 2) MONOCHROMATOR 3) SAMPLE SOLUTION IN CUVETTE 4) PHOTO DETECTOR 5) READOUT DEVICES A spectrophotometer is an analytical instrument used for the objective calculation of visible light, UV light, or infrared light emission or reflection. Spectrophotometers measure intensity as a function of the wavelength of the light source. A spectrophotometer measures the number of photons emitted to estimate the intensity of light spectra absorbed and transmitted by a sample. This provides information on the amount of a compound in the sample. Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution. The basic principle is that each compound absorbs or transmits light over a certain range of wavelength. This measurement can also be used to measure the amount of a known chemical substance. A spectrophotometer is an analytical instrument used for the objective calculation of visible light, UV light, or infrared light emission or reflection. Spectrophotometers measure intensity as a function of the wavelength of the light source. A spectrophotometer measures the number of photons emitted to estimate the intensity of light spectra absorbed and transmitted by a sample. This provides information on the amount of a compound in the sample. Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution. The basic principle is that each compound absorbs or transmits light over a certain range of wavelength. This measurement can also be used to measure the amount of a known chemical substance. • SOURCES OF LIGHT :- Radiation sources should be economic. It should be long lasting show should be stable over time. Example - Tungsten lamp, hydrogen discharge lamp, Deuterium lamp, xenon discharge lamp, mercury are - Part of the UV and visible radiation source is Tungsten lamp. A light source is anything that makes light, whether natural and artificial. Natural light sources include the Sun and stars. Artificial light sources include lamp posts and televisions. Tungsten filament incandescent lamps, particularly tungsten halogen lamps, are often used in illumination systems. UV radiation sources is Deuterium or hydrogen lamp. Range of wavelengths 200-400 nm. A deuterium arc lamp is a low-pressure gas-discharge light source often used in spectroscopy when a continuous spectrum in the ultraviolet region is needed. Plasma "arc" or discharge lamps using hydrogen are notable for their high output in the ultraviolet, with comparatively little output in the visible and infrared. MONOCROMATOR :- It is a device that breaks the polychromatic radiation into comments wavelengths. It converts polychromatic light into monochromatic light. A monochromatic is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. See figure- **FIG NO 09: MONOCROMATOR** A monochromatic is an optical instrument which measures the light spectrum. Light is focused in the input slit and diffracted by a grating. In this way, only one color is transmitted through the output slit at a given time. Spectra are then recorded wavelength by wavelength, rotating the grating. There are modified types of monochromatic, for example the Fastie-Ebert monochromator with a common collimator/refocusing mirror, and devices with two gratings for better resolution. The quality of the diffraction grating can be important for the performance: Its diffraction efficiency determines the power losses. - Monochromatic is a mechanism that emits monochromatic light from a light source. A dispersive element, generally a prism or diffraction grating, is used to create the monochromatic light. - There are two types of monochromatic: prisms and grating systems. **THE MONOCROMATOR UNIT CONSISTS OF:-** - **ENTRANCE SLIT :-** Definition narrow beam of radiation from source provide a narrow optical image of the radiation source. A thin slit in an opaque screen by which light enters a spectrometer. The spectrum thus formed is the image of this slit in each wavelength of light present. - **COLLIMATING MIRROR :-** A collimator is a device which narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction, or to cause the spatial cross section of the beam to become smaller. In optics, a collimator may consist of a curved mirror or lens with some type of light source and/or an image at its focus. - **DIFFRACTION GRATING OR PRISM :-** • Make of quartz disperses the light into specific wavelengths. The prism achieves dispersion due to the difference in the material refractive index according to the wavelength. However, the diffraction grating uses the difference in diffraction direction for each wavelength due to interference. - **FOCUSBING MIRROR :-** • Capture the dispersed light and sharpens the same to the sample via exit slit. • A focusing mirror re-form the image of the entrance slit and focuses it onto the exit slit. • Focusing mirrors (concave mirrors) are characterized by one concave surface with a high reflection coating. The reflective coating allows focusing of a light beam. • When parallel light rays fall on the surface of a concave mirror, all the rays after reflection converge (meet) at a single point (focus). Hence, a concave mirror is also called a converging mirror. SAMPLE SOLUTION IN CUVELTE :- - Liquid sample is usually contained in a cell called as cuvette. Fingerprints are droplets of water disrupt light rays during measurements. • Cuvette from Quartz can be used in UV as well as in visible spectroscopy. Cuvette from glass is suitable for visible but not for UV spectroscopy because it absorb UV radiation. - See figure- ![Sample solution in cuvette](image) Often the sample is a solution, with the substance of interest dissolved within. The sample is placed in a cuvette and the cuvette is placed in a spectrophotometer for testing. The cuvette can be made of any material that is transparent in the range of wavelengths used in the test. A cuvette is a type of sample holder for liquid samples. Often, they are made of plastic, borosilicate glass, or quartz. Stellar Net offers glass cuvettes for experiments in the visible or NIR ranges and quartz cuvettes for experiments in the UV range. Cuvettes also come with two or four polished sides. When you rinse the cuvettes with water, the water dilutes the sample (concentration changes). Therefore, you must rinse the cuvettes with the sample (rather than water) so you can avoid changing the concentration of your sample. PHOTO DETECTOR : A photo detector is a semiconductor device which converts light energy to electrical energy. It consists of a sample P-N junction diode and is designed to work in reverse biased condition. The photons approaching the diode are absorbed by the photodiode and current is generated. Photodetectors, also called photo sensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response. ![Photodiode](image) Photodetectors are sensors that can convert the photon energy of light into electrical signal. The photodetector is also called an optical receiver. It converts the variation in optical power into a corresponding variation in the electric current. As compare to the optical transmitter the design of optical receiver is more complicated just because the receiver must detect weak, distorted signals and then make decisions on what type of data was sent based on an amplified version of this totally distorted signal. TYPES OF DETECTOR :- 1. BARRIER LAYER CELL DETECTOR 2. PHOTO TUBE DETECTOR 3. PHOTO MULTIPLIER TUBE DETECTOR 4. SILICON PHOTODIODE DETECTOR 1. BARRIER LAYER CELL DETECTOR : - Barrier layer cell detector is also called as photo volatile cell. It consists of semiconductor (selenium) which is deposited on strong base ion A very thin layer of silver of gold is placed over the surface of semiconductor. - To act as collector electro radiation when falls on the surface electron on produce. Electron are produce and their it is converted into electric current. To dose not required power supply ![Barrier Layer Cell](image) **FIG NO. 12 BARRIER LAYER CELL** A photoelectric detector which is made of iron coated with a semiconductor film when light from 250-750nm hits this cell, you get a current; this is a cell which is mainly good for intense light sources, because there is not a huge signal enhancement. Also known as a self-generating barrier layer cell. A photoelectric detector that converts radiant flux directly into electrical current. Generally, it consists of a thin silver film on a semiconductor layer deposited on an iron substrate. 2. PHOTO TUBE DETECTOR : UV Visible Spectroscopy - Photo tube detector is also called as photo electric cell detector. When the light is incident upon the photo cell it get converted into electric current. - The current which is created in between cathode and anode is regarded as a measure of radiation on the detector. A phototube or photoelectric cell is a type of gas-filled or vacuum tube that is sensitive to light. Such a tube is more correctly called a 'photo emissive cell' to distinguish it from photovoltaic or photoconductive cells. 5) READOUT DEVICES: - The signal from detector is received by recording system. Recording is done by recording pen. The earliest instruments were simple and directly connected the amplifier detector signal to a chart recorder. Nowadays, all experimental settings are controlled by a computer and detector signal are digitized processed and stored. The device used to accept the signal transmitted from the analyzer and display it for use in process operation or other decision making. Displayed as a measured property or concentration in the accepted units of that property or concentration. - Several types of readout devices are used in modern instruments. These devices include Digital Meters, Recorders, Cathode-Ray Tubes, LCD panels, and Computer Displays. This image shows an example of what a readout will look like from the signal processed. It is the expected output for the determination of lead. The process of removing information from an automatic device (such as a computer or sensor) and displaying it in an understandable form. A digital readout (DRO) is a numeric display, usually with an integrated keyboard and some means of numeric representation. Its integral computer reads signals generated by linear encoders or (less frequently) rotary encoders installed to track machine axes, using these measures to keep track of and display to a machine operator the work piece position (e.g., milling machines), or tool position (lathes, grinders, etc.) in space. Digital screen to record an UV spectrograph with absorbance against the wavelengths. Definitions of recording system. Audio system for recording sound. Type of audio system, sound system. A system of electronic equipment for recording or reproducing sound. Signal. Many measuring instruments also record the quantities they measure; see Category: Measuring instruments. Digital recording is the process of storing binary data in the form of a two-level magnetization pattern. Digital recording is also referred to as saturation recording since channel bits are recorded by saturating the media either in the positive or negative direction. 9) TYPES OF SPECTROPHOTOMETER: A spectrophotometer is an analytical instrument used for the objective calculation of visible light, UV light, or infrared light emission or reflection. Spectrophotometers measure intensity as a function of the wavelength of the light source. A spectrophotometer measures the number of photons emitted to estimate the intensity of light spectra absorbed and transmitted by a sample. This provides information on the amount of a compound in the sample. FIG.NO 13: TYPES OF SPECTROPHOTOMETER There are generally two types of spectrophotometers: a single beam, and double beam. Single beam spectrophotometers use a single beam of light - visible or UV- which passes through a sample in a cuvette. According to different wavelengths and application fields, spectrophotometers can be divided into visible spectrophotometer, ultraviolet visible spectrophotometer, infrared spectrophotometer, fluorescence spectrophotometer and atomic absorption spectrophotometer. SINGLE BEAM SPECTROPHOTOMETER: Single beam spectrophotometers determine color by measuring the intensity of the light sources before versus after a test sample is inserted. This light source is modulated (turned on and off) to differentiate the light coming from the light source versus the light coming from the flame. A UV-Vis spectrophotometer is used to determine the absorption of light from a sample and can be used as a detector for HPLC. A sample is placed in the UV/VIS beam and absorbance versus wavelength is measured. UV-visible spectrophotometers have five main components: the light source, monochromator, sample holder, detector, and interpreter. The standard light source consists of a deuterium arc (190-330 nm) and a tungsten filament lamp (330-800 nm), which together generates a light beam across the 190-800 nm spectral range. DOUBLE BEAM SPECTROPHOTOMETER: A double beam spectrophotometer is an instrument that determines the absorption of light in liquid or gas samples in graduated cylinders. Its components are: Monochromator. Detector. Light source. For a double-beam UV/Vis Spectrophotometer: A beam of light from a visible and/or UV light source is separated into its component wavelengths by diffraction grating or monochromator. Each monochromatic (single wavelength) beam in turn is split into two equal intensity beams by a half-mirrored device. An important advantage of a double-beam spectrophotometer over a single-beam spectrophotometer is that a double beam instrument permits compensation for source power fluctuations greatly improving S/N and extension to dilute solution samples and measurements with gases. A typical double beam UV-visible spectrophotometer consists of: A light or energy source, which is typically a lamp. A filter or a monochromator that is attached to the device for the selection of the wavelength of light. A place for cuvettes to read the measurements. 10) APPLICATION OF UV VISIBLE SPECTROSCOPY:- Used to determine impurities Determine double bond and triple bonds. Determine aromatic and aliphatic conjugation Alpha and beta unsaturation. Quantitative and qualitative analysis. Pharmacokinetic properties. Structural elucidation in compound. Ultraviolet-visible (UV-Vis) spectroscopy is a widely used technique in many areas of science ranging from bacterial culturing, drug identification and nucleic acid purity checks and quantitation, to quality control in the beverage industry and chemical research. Growth of metal nanoparticles in polymeric network or growth of polymeric network around metal nanoparticle core can be studied by using UV/Vis spectroscopy. This technique can also be used for investigation of various applications of hybrid materials in catalysis, photonics, and sensing. Spectrophotometry is used for the quantitative determination of a great variety of substances in solution. These range from water and waste water analysis, pharmaceutical quality control and food analysis. UV/Vis molecular absorption is routinely used for the analysis of narcotics and for drug testing. The presence of these drugs can be confirmed from their absorption maxima i.e. Amax or by comparing the UV/visible spectra of these drugs with spectra of authentic sample. Atomic absorption spectroscopy is utilized across many industries and is instrumental in the detection of metals within a sample. As such, this process is commonly utilized in pharmacology, archaeology, manufacturing, mining, and forensics. Besides chemical analysis, there are many physical methods performed to characterize purity and determine the mixture of substances. Even though there are many techniques such as determination of melting point, refractive index, and density. Ultraviolet and Visible light spectroscopy is widely applied in a market segment, research areas, production, and quality control for the classification and study of substances. 11) CONCLUSION: UV-visible spectroscopy is a valid, simple and cost effective method for determining the concentration of absorbing species if applied to pure compounds, and used with the appropriate standard curve. Ultra violet/visible spectroscopy is an analytical technique that is used to determine qualitatively and quantitatively for the estimation of different ions. It is a powerful technique for resolution enhancement when signal overlaps interference occurs. This technique may also be used in many other industries. For example, measuring a colour index is useful for monitoring transformer oil as a preventative measure to ensure electric power is being delivered safely. 12) REFERENCE: 4) Wavelength Accuracy in UV/VIS Spectrophotometry [Internet]. Available from https://www.mt.com/ch/en/home/library/white-papers/lab-analytical- 10) Chatwal GR. Instrumental methods of chemical analysis. Pg. no. 2.116-2.122. 11) Sharma YR. Elementary Organic analysis, Principles and chemical applications. Pg. no.12 -14
Article Towards 6G Satellite–Terrestrial Networks: Analysis of Air Mobility Operations Krishnakanth Mohanta † and Saba Al-Rubaye * † Cranfield University, Bedford MK43 0AL, UK * Correspondence: s.alrubaye@cranfield.ac.uk † These authors contributed equally to this work. Abstract: This paper presents an analytical exploration of sixth-generation (6G) satellite–terrestrial integrated networks, focusing specifically on their applications within air mobility operations, such as those involving unmanned aerial vehicles (UAVs). As the integration of satellite and terrestrial networks promises to revolutionize mobile communication by extending coverage and enhancing connectivity, this study delves into two critical aspects: link budget analysis and handover and mobility analysis for UAVs. The link budget analysis assesses the communication requirements necessary to ensure robust and consistent connectivity between satellites and UAVs, accounting for factors such as path loss, antenna gains, and power transmission. Meanwhile, the handover and mobility analysis investigates the challenges and solutions associated with UAVs transitioning between different network nodes and layers in a dynamic aerial environment. This paper utilizes theoretical models and simulations to provide insights into the design and optimization of these networks, aiming to enhance the reliability and efficiency of UAV operations in the context of the emerging 6G landscape. The findings propose not only technological advancements in network architecture but also practical guidelines for the deployment of UAVs in complex environments, marking a significant step toward the realization of a fully integrated, satellite-terrestrial ecosystem. Keywords: mobility analysis; handover; 6G; satellite–terrestrial networks; link budget 1. Introduction Urban air mobility (UAM) is a subset of advanced air mobility (AAM), and it is defined as safe and efficient air traffic operations for passenger and cargo transport within the urban environment, with an on-board pilot or a remote pilot in command (RPIC) or a completely autonomous unmanned aircraft system (UAS) [1,2]. Such a technological capability requires a robust communication system (among other systems) capable of operating in a congested urban environment. The UAM system demands a communication system that has good availability, integrity, and security for the safety of its operations in the urban environment. In this paper, we study the communication systems requirements to support UAM operations. To do so, existing and potential communication systems for UAM are reviewed; they include 3rd Generation Partnership Project (3GPP) 6G technology [3,4]. LEO constellations will be used to provide reliable and fast broadband services to the public in the future and improve communication capabilities and efficiency in various fields [5]. In future 6G technology, space–ground-integrated-network, low-Earth-orbit satellites will play an especially important role [6,7]. Furthermore, this paper elaborates on a performance analysis of the data link for communication between ground stations to unmanned aerial vehicles (UAVs) using link budget analysis and taking weather attenuation and the Doppler effect into consideration. Additionally, the effect of altitude on the quality of service in terms of latency was studied and is presented. These studies will help design robust communication system architectures for UAVs in remote regions. Urban air mobility (UAM) vehicle operations require specialized communication systems that prioritize robustness and efficiency. Central to these requirements is a resilient command and control (C2) data link, responsible for managing critical flight and safety systems, telemetry data, and communication between the UAM vehicle and the ground station [8–10]. This link must be immune to both unintentional and intentional interference, such as jamming and spoofing, with contingency plans for quick recovery should disruptions occur [11,12]. Additionally, the communication module on the vehicle should be lightweight to conserve energy, thus enhancing the UAV’s range and endurance by allowing more power to be allocated to propulsion systems. UAM communication systems must adapt to the unique challenges posed by the operating environment [13]. They must ensure uninterrupted service across urban [14], rural, or remote terrains at a typical altitude range of 600 to 5000 feet, even necessitating transitions to satellite communications (SATCOM) when terrestrial networks are unavailable [15–17]. Introducing SATCOMs also brings many challenges, including interference management and resource optimization [18–21]. High-speed UAV operation requires the system to accommodate Doppler shifts without failure. Additionally, precise location detection is crucial for collision avoidance, while managing interference is vital to prevent potentially catastrophic failures. To maintain operational efficiency and safety, the system must also support minimal signal losses and low latency, ensuring reliable, real-time communication in urban settings. Satellite–terrestrial networks employ an architecture that merges the extensive reach of satellite systems with the high capacity and low latency of terrestrial networks [22]. This approach facilitates coverage extension to remote areas and significantly enhances the performance capabilities of Internet-of-Things (IoT) applications; therefore, it is positioned as a backbone for future smart ecosystems [23]. However, despite these advancements, the specific deployment and optimization of these networks for UAV operations pose unique challenges, particularly in maintaining reliable connectivity in dynamic aerial environments. Current research has shown that, while theoretical models for network integration exist, practical applications, especially those involving UAVs, often encounter issues with efficient handover mechanisms and robust link budget management [24,25]. Our manuscript extends this discussion by analyzing the link budget and handover and mobility for UAVs within a 6G satellite–terrestrial framework. This study leverages recent advancements and identifies shortcomings in existing systems to enhance both the theoretical understanding and practical implementation of integrated networks. The communication system for UAVs and the data links are visualized in Figure 1 below. The introduction of satellite–terrestrial networks could enhance the range of operations of UAVs, especially in remote regions. Whitworth et al. [26] carried out link budget analysis for 5G communication systems, considering only ground base stations. This paper further extends their study by introducing satellite networks. The contributions of this paper are as follows: - A detailed link budget analysis for UAV communication within satellite–terrestrial networks. This analysis considers unique factors such as UAV altitude adjustments and atmospheric conditions, which are crucial for ensuring reliable and robust communication links. - The paper proposes a handover strategy that facilitates seamless network transitions for UAVs. - Utilizing theoretical models and simulations, the study evaluates the performance of satellite network under various weather scenarios. Choosing link budget and handover performance analysis for 6G satellite–terrestrial networks targeting UAV operations addresses crucial connectivity needs. Link budget analysis ensures that communication links between UAVs and satellites have adequate signal strength for effective communication, which is crucial for UAVs operating at various altitudes and speeds. Handover performance analysis maintains continuous service as UAVs travel through their designated path, which is crucial for minimizing disruptions during transitions. These areas are interlinked, as a robust link budget underpins stable connections essential for smooth handovers, thus improving network reliability and service continuity for UAVs in dynamic environments. Figure 1. Communication system for UAM. 2. System Architecture The proposed system architecture integrates 6G satellite and terrestrial networks to support unmanned aerial vehicles (UAVs) in a range of operational scenarios, from commercial deliveries to emergency services. This architecture is designed to leverage the strengths of both satellite and terrestrial technologies, ensuring seamless connectivity, high throughput, and low latency. It includes several key components: a satellite constellation, terrestrial base stations, UAVs as mobile nodes, and a network management system. The system has the following components: - **Satellite constellation**: A constellation of low-Earth-orbit (LEO) satellites provides wide coverage and high-bandwidth communication links. These satellites are equipped with advanced beamforming capabilities to dynamically focus connectivity on specific areas or UAVs, enhancing signal strength and reducing interference [27–30]. - **Terrestrial network**: Comprising 6G base stations, this network layer offers high-speed, low-latency connections in urban and suburban areas [29]. The terrestrial network serves as the primary means of communication where available, with the capability of handing over to the satellite layer when UAVs move out of terrestrial coverage [31]. - **UAVs as mobile nodes**: UAVs are equipped with dual-mode communication systems capable of connecting to both satellite and terrestrial networks. These systems automatically switch between satellite and terrestrial links based on the signal quality, network load, and predefined operational parameters. - **Network management system (NMS)**: This central system coordinates between the satellite and terrestrial networks. It manages resource allocation, monitors network health, and orchestrates handovers between satellites and terrestrial nodes. The NMS uses predictive algorithms to optimize routes and connectivity for UAVs based on their flight plans and network conditions [32]. 2.1. System Design The system design focuses on the following key aspects: 1. **Link budget analysis**: The link budget is analyzed to determine the maximum range and data throughput achievable under various conditions, including altitude, speed, and weather. This analysis informs the selection of communication technologies and antenna configurations. 2. Signal handover strategy: An effective signal handover strategy is developed to ensure seamless communication continuity as UAM vehicles transition between base-station coverage areas. The entropy method is used to evaluate signal parameters and determine the optimal handover point. 2.2. Testing and Evaluation The proposed system will be thoroughly tested and evaluated in a simulated environment before deployment in a real-world UAM ecosystem. The testing will focus on the following aspects: 1. Link Performance: Link performance will be measured under various conditions to validate the link budget analysis and ensure that data transmission meets the requirements. 2. Handover Performance: Handover success rate will be evaluated to ensure seamless communication continuity during vehicle transitions. 3. Link Budget Analysis A link budget analysis is performed to evaluate the feasibility and reliability of the communication system. This analysis involves calculating all the gains and losses encountered along the transmission path to determine whether the signal strength is sufficient for effective communication. This assessment takes into account various factors such as distance, frequencies, antenna gains, weather, and signal losses. [33] This research explores the following: - An evaluation of path losses in different weather conditions. - The effect of altitude on the QoS parameters of the UAV communication system. The system parameters considered for the study are tabulated below in Table 1. <table> <thead> <tr> <th>System Parameters</th> <th>Specification</th> </tr> </thead> <tbody> <tr> <td>Operating (center) frequency</td> <td>3.5 GHz</td> </tr> <tr> <td>Antenna gain (drone-mounted)</td> <td>10 dBi</td> </tr> <tr> <td>UAM vehicle velocity</td> <td>45 m/s</td> </tr> <tr> <td>Polarization</td> <td>VV (Vertical)</td> </tr> <tr> <td>Transmitter cable and connector loss</td> <td>3 dB</td> </tr> <tr> <td>Receiver antenna diameter</td> <td>1.5 m</td> </tr> <tr> <td>Antenna efficiency</td> <td>75%</td> </tr> <tr> <td>Base station power</td> <td>38 dBm (6G ground station)</td> </tr> <tr> <td>Noise temperature</td> <td>300 K</td> </tr> <tr> <td>Rain rate</td> <td>80 mm/h</td> </tr> <tr> <td>Specific attenuation (k)</td> <td>2 dB/km</td> </tr> <tr> <td>Polarization constant (a) (for vertical polarization)</td> <td>0.07</td> </tr> <tr> <td>Specific attenuation for dry air (τd)</td> <td>0.08 dB/km</td> </tr> <tr> <td>Specific attenuation for water vapor (τw)</td> <td>0.5 dB/km</td> </tr> <tr> <td>Minimum required C/N</td> <td>−120 dB (for 6G)</td> </tr> <tr> <td>Satellite altitude</td> <td>800 km</td> </tr> </tbody> </table> The values considered for the analysis were assumed based on a literature review, as no standards have been established for 6G yet [34,35]. 3.1. Link Margin The link margin represents the excess power available, calculated as the difference between the received power ($P_{RX}$) and the minimum power required for the receiver’s reliable communication, known as receiver sensitivity (RS). A positive link margin is essential for the effective establishment of a communication system. The formula for determining the link margin is outlined in Equation (1) $$LM = P_{RX} - RS$$ (1) 3.2. Link Budget Equation The general link budget equation is shown below (Equation (2)): \[ P_{RX} = P_{TX} + G_{TX} - L_{TX} - L_{FS} - L_{M} + G_{RX} - L_{RX} \] (2) where the following applies: \( P_{RX} \): received power (dBm). \( P_{TX} \): transmitter output power (dBm). \( G_{TX} \): transmitter antenna gain (dBi). \( L_{TX} \): transmitter losses in dB. \( L_{FS} \): free space path loss in dB. \( L_{M} \): other losses in dB. \( G_{RX} \): receiver antenna gain (dBi). \( L_{RX} \): receiver losses in dB. For the given Equation (2), the transmitter power (\( P_{TX} \)), transmitter loss (\( L_{TX} \)), and receiver antenna gain (\( G_{RX} \)) are given in Table 1. To calculate the transmitter gain, the following Equation (3) is used: \[ G_{TX} = 10 \log \left( \eta \times \left( \frac{\pi D}{\lambda} \right)^2 \right) \] (3) where the following applies: \( \eta \): antenna efficiency. \( D \): antenna diameter. \( \lambda \): wavelength. 3.3. Attenuations The communication system is expected to experience attenuation losses due to the various factors outlined below: - **Free space path loss**: An essential component of the link budget analysis, the free space path loss (FSPL) quantifies the reduction in signal strength as it travels through open space unimpeded by any obstacles or interference. The formula for calculating the free space loss (\( L_{FS} \)) is presented in Equation (4). \[ 20 \log \left( \frac{4\pi d}{\lambda} \right) = 20 \log(d) + 20 \log(f) + 20 \log(4\pi/c) \] (4) where \( d \) represents the distance between the base station/satellite and the UAS. - **Doppler effect**: Given that the UAS will be moving at some speed, the Doppler effect must be considered when determining the received power (\( P_{RX} \)). This consideration is incorporated into the formula as depicted in Equation (5), as all the variables in the equation are expressed in dB. \[ P_{RX} = P_{TX} + G_{TX} - L_{TX} - L_{FS} - L_{M} + G_{RX} - L_{RX} \pm 10 \log(f_{ds}) \] (5) where \( f_{ds} \) is the shift in the Doppler effect given in Equation (6): \[ f_{ds} = v_{rel} \frac{f}{c} \] (6) \( v_{rel} \) is the relative velocity of the UAV with respect to the base station/satellite. In the case of satellites, the relative velocity is considered to be the orbit velocity of the satellite. In Equation (5), the \( \pm \) symbol indicates the direction of travel of the UAV—whether it is moving towards or away from the base station. For this particular scenario, it is assumed that the UAV is departing from the base station; therefore, the ‘−’ sign is applied. - Atmospheric attenuation: Atmospheric attenuation, mainly due to atmospheric gases, significantly influences the link budget of communication systems, particularly at higher frequencies. This type of attenuation adds to the total path loss and impacts the strength of the signal that is received. The attenuation, represented as $\gamma$ (dB/km), is determined using the formula shown in Equation (7). $$\gamma = \gamma_o + \gamma_w$$ \hspace{1cm} (7) In this context, $\gamma_o$ represents the specific attenuation due to dry air, and $\gamma_w$ signifies the specific attenuation due to water vapor. The attenuation of the signal caused by the atmosphere is determined by multiplying the overall specific attenuation, $\gamma$, by the distance, $d$, that the signal travels through the gas. Therefore, the power loss from gas attenuation, denoted as $L_{atm}$, can be computed using Equation (8). $$L_{atm} = \gamma d$$ \hspace{1cm} (8) - Rain attenuation: Rain attenuation is the decrease in signal strength that occurs due to rain in the path of communication. It is a crucial consideration in link budget analysis, particularly for AAM communication systems that operate at frequencies prone to signal weakening caused by rain. Rain attenuation is expressed in the following formula (refer to Equation (9)): $$A_{rain} = kR^\alpha$$ \hspace{1cm} (9) In this equation (9), the following applies: - $R$ represents the rain rate in mm/h. - $k$ denotes the specific attenuation measured in dB/km. - $\alpha$ is the polarization constant, which can differ, based on the polarization orientation. $k$ and $\alpha$ are considered to be $k_V$ and $\alpha_V$ for vertical polarization. The scenario presented considers vertical polarization only. The impact of this attenuation on signal losses due to rain can be calculated as shown in the next equation, where $v$ is the vertical component of the distance from the UAV to the base station. $$L_{rain} = A_{rain} * v$$ \hspace{1cm} (10) In the case of satellite communications, the rain and atmospheric attenuations are limited to a certain altitude. The rain attenuation happens below the clouds, and the atmospheric attenuation significantly drops beyond the stratosphere. This can be visualized using Figure 2. Figure 2. Attenuation limits along the signal path. 3.4. Total Path Loss The path loss model encompasses all signal losses incurred during propagation from the transmitter to the receiver, essentially aggregating all individual losses. For the specific scenario in question, the path loss can be computed using the following formula: \[ Path \ Loss = FSPL - 10 \log(f_{ds}) - L_{gas} - L_{rain} \] (11) In addition to received power, two additional metrics that can be utilized to assess the link budget analysis include the following: - The carrier-to-noise ratio: This ratio, represented in Equation (12), measures the received carrier strength to the received noise. This is also called the signal-to-noise ratio (SNR). \[ SNR = \frac{P_{RX}}{\text{Noise \ Power} \ (N)} \] (12) - Latency Latency denotes the delay that signals encounter as they pass through a communication system. Although latency is not usually included in standard link budget analyses, it plays a critical role in the planning and performance assessment of communication frameworks, particularly in situations requiring an immediate or time-sensitive exchange of data. The formula for latency \(t\) is given in Equation (13). \[ t = \frac{\text{Distance} \ (d)}{c} \] (13) The latency equation presented does not factor in the UAV's speed. However, in practical scenarios, it would likely be influenced by the processing times at both the transmitter and receiver ends. Since we lack specific data regarding this, we assume that processing occurs instantaneously, without any delay. These equations are applied to perform the link budget analysis for the given scenario. 4. Communication Handover Handover refers to the mechanism through which mobile devices transition between networks. In this research, the focus is on UAVs as moving devices. As a UAV travels along its route, it must switch from one network tower (or base station) to another as it enters and exits the coverage areas of these stations. Handovers can be a switching of networks between the same type of network (horizontal handover) or to a different type of network (vertical handover). Vertical handovers also include handovers to non-terrestrial networks like satellite networks and high-altitude platforms (HAPs) to ensure reliable and robust data links with flights and UAVs traveling above remote areas [4,36]. This process is illustrated in Figure 3. There are many handover strategies discussed and studied for satellites. One of the strategies proposed is by Deng et al. [37], by whom an assisted soft handoff algorithm was introduced, building on the WCDMA system’s soft handoff approach and using location information to calculate the residence time. However, this method was proposed for GEO satellites. For LEO satellite-based communication systems, Wu et al. proposed handovers based on a ‘potential game’ for mobile terminals [38]. There are other strategies for handovers that use the tracking time, signal quality, and maximum separation angle as the decision parameter [39]. While there are multiple handover strategies, entropy-based handovers are preferred for urban air mobility applications [40]. This is because of the following reasons: - Entropy-based methods can dynamically adjust to changes in various link parameters like the received signal strength, latency, capacity of satellite, etc., reducing the likelihood of dropped connections. • UAM vehicles, such as drones and air taxis, move at high speeds and altitudes, which require rapid adjustments in network connections. Entropy-based systems can handle these dynamics more effectively than traditional methods [41]. • This method is scalable. When more satellites or parameters are introduced, appropriate weights can be designated for them. Figure 3. Visualization of handovers. Entropy-Based Handover Entropy-based handover calculates the entropy of various handover criteria—such as the signal strength, network load, and user mobility—to determine their respective variability and impact on the network. Criteria with lower entropy (less variability) are considered more stable and are given a heavier weight in the decision-making process. This weighting helps in prioritizing handover targets based on a comprehensive, data-driven evaluation. The entropy weight method is employed to evaluate the spread of values across various criteria or indices. It quantifies the level of differentiation among these criteria, allocating increased weights to indicators that show more significant dispersion [41]. The mathematical formulation of the entropy method, essential for decision-making in signal handover strategies, is detailed in Equations (14) and (18), as per [40]. The criteria for a handover are as follows: \[ P_{\text{new}} > P_{\text{old}} + \text{Entropy} \] (14) Here, \((P_{\text{new}})\) and \((P_{\text{old}})\) represent the power from the new and the old base stations, respectively. The term ‘Entropy’ in this context is derived from the entropy weight method, illustrated in Equation (15): \[ E_i = -\frac{\sum_{j=1}^{n} p_{ij} \cdot \ln p_{ij}}{\ln n} \] (15) In this equation, \(p_{ij}\) stands for the normalized values for the \(i^{th}\) indicator and \(j^{th}\) sample, defined as follows: \[ p_{ij} = \frac{x_{ij}}{\sum_{j=1}^{n} x_{ij}} \] (16) For the analysis, three ground base stations and one satellite were considered. Given that there are four base stations in total \((n = 4)\), the specific entropy for signal strength is given as follows: \[ E_i = -\frac{\sum_{j=1}^{4} p_{ij} \cdot \ln p_{ij}}{\ln(4)} \] (17) Entropy = $-\sum (p(x)^* \log_4 (p(x)))$ \hspace{1cm} (18) In this analysis, for simplicity, we consider just one indicator, namely the received signal strength (RSS), and with three samples from three base stations. This assumption was made since the study was done for a single satellite. The introduction of new satellites or a constellation of satellites would require inputs of other indicators like the capacity, remaining service time, and satellite load (capacity). The weights for other indicators are not considered, thereby simplifying the weighted entropy method to a basic entropy calculation. The standardized values of RSS are computed as follows: $$p_j = \frac{RSS_j}{\sum_{j=1}^{4} RSS_j}$$ \hspace{1cm} (19) This study aimed to develop a signal handover strategy for drones, focusing solely on RSS. The network conditions before and after handovers are illustrated, along with the corresponding signal strengths. The assumptions for the study include the following: - A drone travels in a straight flight path along the X-axis. - The rain and gas attenuation are considered. - A constant UAV altitude and a velocity of 45 m/s are involved. - The satellite is on the XY plane - The drone has an elevation mask of 60°, as shown in Figure 4. Figure 4. Visualization of the elevation mask on the drone. 5. Results Using the methods discussed in the previous section, the link budget analysis and mobility-and-handover analysis were carried out by simulating the provided problem statement in MATLAB R2024a. The results are discussed below: 5.1. Link Budget There are four studies that were done on link budget analysis, which are mentioned below: - The effect of weather attenuation on the received power at different elevation angles of a UAV receiver: Weather attenuation significantly impacts the quality of the com- munication link. By evaluating how weather conditions affect the received power at different elevation angles, the research provides insights into the robustness of the communication link across diverse atmospheric conditions. This is essential for designing UAV communications that remain reliable in adverse weather. - The effect of the altitude of a UAV on the link parameters: The altitude of a UAV directly influences several link parameters, such as the path loss, delay, and signal strength. Higher altitudes may facilitate a better line of sight with satellites, but they could also result in increased path losses with terrestrial base stations, as reported in [26]. Evaluating this effect allows for the optimization of UAV operating altitudes to balance the benefits of improved satellite visibility against the potential disadvantages of increased path losses with terrestrial links. - Path loss vs. elevation angle: The path loss varies with the elevation angle due to the changing distance and propagation environment between the transmitter and receiver. This evaluation helps in understanding how the geometric configuration of a satellite and a UAV impacts the efficiency of the communication link. Optimizing the elevation angle can minimize the path loss, thereby enhancing the overall performance of the network. - Link margin vs. elevation angle: The link margin, the difference between the received signal strength and the minimum required signal strength for acceptable performance, is a critical parameter in ensuring communication reliability. By studying how the link margin varies with elevation angle, research can determine the most reliable operational angles for UAVs. This is crucial for ensuring that UAVs maintain sufficient link margins to handle unexpected variations in signal strength due to dynamic changes in their operating environment. 5.1.1. Effect of Weather Attenuation or Received Power To study the effect of attenuation due to weather, the received signal was analyzed for a fixed-point drone. The received signal strength is noted for every elevation angle the satellite achieves with the drone. This can be visualized using Figure 5. ![Figure 5. Visualization of analysis setup.](image) This analysis was carried out for three cases, namely the following: - Free space. - Atmospheric attenuation only. - Atmospheric and rain attenuation. For this analysis, the UAV was considered to be at a height of 500 meters above the Earth’s surface. The power received for each of the three cases mentioned above at different elevation angles from the drone can be seen in Figure 6. Since the drone has an elevation mask of 60°, the elevation angle varied from 60° to 120°. From Figure 6, it can be inferred that the received power is reduced significantly due to atmospheric attenuation compared to the one received in free space. Rain attenuation further reduces the received power. There is a negligible loss in signal strength without attenuations, and hence, the received power is approximately constant with varying elevation angles. Similarly, the carrier-to-noise ratio or SNR variation due to various attenuation is shown in Figure 7. From the results, we can infer that weather effects significantly impact the signal quality. Bad weather may result in a lower range for the satellite. The signal quality would be best when the elevation angle would be 90 degrees, i.e., the satellite, the UAV, and the center of the Earth would fall in a straight line. Latency and FSPL do not vary with the attenuation. This is because these parameters are functions of distance only. The distance between the UAV and the satellite would vary with changes in the elevation angle. The plots showing their variation with the elevation angle are shown in Figures 8 and 9, respectively. **Figure 6.** Received power with various attenuation. **Figure 7.** C/N vs. horizontal distance for different attenuations. **Figure 8.** Latency vs. horizontal distance. Figure 9. FSPL vs. horizontal distance. 5.1.2. Effect of Altitude of UAV on Link Parameters at a Given Speed As discussed in the introduction, UAM requires communication systems at different altitudes. The link parameters and quality of service vary with changes in altitude. The analysis below was done while considering the power received via the UAV after rain attenuation. The link parameters vs. the distance curves at various altitudes with the UAV traveling at 45 m/s are shown in the figures below. The Doppler effect was considered when evaluating the drone’s relative velocity, considering the satellite’s orbit velocity. Figure 10 shows the variation in the received power as we increase the altitude. It is evident from the figure that, as we increase the altitude, more power is received. This is due to fewer losses along the path, as the path becomes shorter. It can be noted that, beyond the altitude of 2000 meters (above the cloud altitude), the change in the received signal strength is much less. This happens since rain attenuation is no longer a factor beyond 2000 m in altitude. Figure 10. Received power vs. horizontal distance at different altitudes. Figure 11 shows the variation in FSPL as we increase the altitude. From the result shown in the figure, we can infer that the free path loss decreases with an increase in altitude, while it increases as the UAV moves laterally away from the satellite at a constant altitude. This is because the distance between the satellite and the UAV decreases. Naturally, this trend is the opposite of what was observed for ground base stations in [26]. The carrier-to-noise ratio (SNR) and latency were calculated and plotted against the horizontal distance for different altitudes. The results are shown in Figure 12 and Figure 13, respectively. The SNR would decrease as the UAV moved closer to the satellite, and there would be less noise as you moved closer to the source of the signal. Latency drops as the UAV moves to a higher altitude in the case of satellites as the distance between the UAV and the satellite is reduced. These results show that the link budget parameters for satellite communications exhibit opposite trends when compared to ground base stations [26]. This is solely due to the direction of the source of the signal. When the altitude of the UAV is increased, it moves closer to the satellite but away from ground base stations. Figure 11. FSPL vs. horizontal distance at different altitudes. Figure 12. C/N vs. horizontal distance at different altitudes. Figure 13. Latency vs. horizontal distance at different altitudes. From these figures, it can be noted that both C/N and latency decrease with an increase in altitude. One of the factors important to note here is that, due to the vertical polarization of the rain attenuation, the power loss is more in the vertical direction as compared to the horizontal direction, and hence, for the given problem statement, a UAV moving vertically up is more likely to lose its connection to the base station compared to a UAV moving horizontally due to rain. 5.1.3. Path Loss vs. Elevation Angle Figure 14 shows the path loss of the signal, considering the free-space loss, weather attenuation, and Doppler effect. The minimum path loss occurs when the elevation angle is 90 degrees. Hence, the best signal quality is achieved when the satellite is directly above the UAV. As the satellite moves away from the UAV, the path loss gradually increases. ![Figure 14. Path-loss vs. horizontal distance.](image) 5.1.4. Link Margin For the given minimum C/N required (i.e., $-120$ dB), and an altitude of 500 meters, the link margin was calculated and is shown in Figure 15. From the figure, we observe that the link margin is not positive throughout the change in the elevation angle from 60° to 120°. The 6G communication link can be maintained only when the link margin is positive. Hence, it can be said that, even though the satellite is in the visible range of the receiver drone, it is not always possible to establish a 6G link. The elevation angle needs to be roughly between 80 and 100 to maintain a 6G communication link ($\theta_{lim-elevation} = \{80°, 100°\}$). ![Figure 15. Link margin vs. horizontal distance.](image) From the link margin, the range of the 6G satellite-terrestrial network can be determined. The elevation angle and the range where the link margin is positive can be related using the following equations. Figure 16 can be used to understand the calculations. \[ \theta = 90^\circ - \theta_{\text{lim-elevation}} \tag{20} \] \[ \alpha = \theta - \arcsin \left( \frac{R_e}{R_{\text{sat}}} \sin \theta \right) \tag{21} \] \[ \text{Range}_{6G} = R_e(2\alpha) \tag{22} \] The above equations, Equations (20)–(22), were used to calculate the range of the 6G satellite network at 250 km on the ground. 5.2. Mobility and Handover Analysis The handover analysis was carried out for a UAV traveling at a constant altitude of 500 m. The UAV communication link has to be handed over between various ground stations and satellites along its path to maintain constant connectivity. This is shown in Figure 17. The assumptions for the ground base stations are as follows (Table 2). The coordinates \((-1000, 0, 0), (2000, 800, 0),\) and \((9000, -3000, 0)\) represent a deliberate placement of base stations across a broad geographic area. This distribution allows for the assessment of UAV communication effectiveness over varying distances and directional paths, which is crucial for testing the network’s handover protocols and signal continuity. By setting the base stations at these points, there is an overlap of coverage areas, which is essential for evaluating the handover algorithms. The 6G terrestrial base station is assumed to have 38 dBm transmitter power [34]. The handover analysis was carried out along the UAV path, and the active base station is shown in Figure 18. Table 2. Initial values for handover analysis: Case-1. <table> <thead> <tr> <th>Parameter</th> <th>Value</th> </tr> </thead> <tbody> <tr> <td>BS1 coordinates</td> <td>(-1000, 0, 0)</td> </tr> <tr> <td>BS2 coordinates</td> <td>((2000, 800, 0))</td> </tr> <tr> <td>BS3 coordinates</td> <td>((9000, -3000, 0))</td> </tr> <tr> <td>Frequency (f)</td> <td>3.5 GHz</td> </tr> <tr> <td>UAV initial position (m)</td> <td>0, 0, 500</td> </tr> <tr> <td>UAV final position (m)</td> <td>9000, 0, 500</td> </tr> <tr> <td>UAV velocity</td> <td>45 m/s</td> </tr> <tr> <td>Attenuation constants</td> <td>Same as Table 1</td> </tr> <tr> <td>Power BS1</td> <td>8 dB (6G ground station) [34,35]</td> </tr> <tr> <td>Power BS2</td> <td>8 dB (6G ground station)</td> </tr> <tr> <td>Power BS3</td> <td>8 dB (6G ground station)</td> </tr> <tr> <td>Signal threshold</td> <td>(-120) dB (assumed for 6G)</td> </tr> </tbody> </table> Figure 18. Serving base station along the UAV path. Figure 18 shows that there are four handovers taking place along the UAV path. Serving BS = 0 means the signal is lost, as the RSS is below the signal threshold. For the considered use case, since the serving base station is never zero, constant connectivity is maintained throughout the flight path. The received signal strength (RSS) of the received signal from each of the stations can be observed in Figure 19. From Figure 19, it can be seen why there are four handovers. The received signal strength of the new signal is stronger than the sum of the old signal strength and its entropy at that position. The maximum signal strength received via the drone is observed to be higher than the signal threshold of $-120$ dB, considered for 6G connectivity. Another interesting inference from the graph is that, even though the satellite comes into the visible range at $x = 4000$ m, the signal strength is not enough to sustain 6G connectivity. 6. Discussion The assumptions made about drone (UAV) flight conditions in this study, including the use of only one satellite for comparison, constant-altitude travel in a straight line, and 2D analysis, significantly shape the interpretation and applicability of the results. Each of these assumptions simplified the real-world complexities of UAV operations and satellite communications, which may have influenced the validity and generalization of the findings. The use of a single satellite to compare with ground stations limited the analysis to a scenario where interference from other satellites or overlapping signals was non-existent. In reality, multiple satellites might be available, offering alternative communication links and affecting the signal quality due to interference. Relying on a single satellite may result in an overestimation of the signal reliability and strength, as it does not account for potential satellite malfunctions or suboptimal positioning relative to the UAV. The results might suggest better connectivity or fewer handovers than might actually occur in a multi-satellite environment where handover decisions could be more dynamic and complex. For the link budget, a straight-line path for the UAV was assumed. This may have led to an oversimplification of the analysis, potentially making the handover algorithms less effective in adaptive or complex flight patterns encountered in practical applications. The UAV, the satellite, and the center of the Earth were assumed to be in the same plane, which meant that the analysis was 2D. The exclusion of 3D spatial factors could have led to inaccuracies in predicting the signal strength and handover performance, making the results less applicable to scenarios where the UAV’s relative altitude and geographic positioning vary significantly from the satellite. While the study’s assumptions streamlined the modeling and analysis, making the complex problem of UAV-to-satellite communications more tractable, they introduced limitations that could affect the practical application of the research findings. Recognizing these limitations is crucial for interpreting the results and for considering further research that incorporates more dynamic and realistic flight patterns and satellite environments. This acknowledgment also guides the development of more robust and adaptive communication systems that can handle the complexities of real-world UAV operations. 7. Conclusions The link budget analysis achieved a positive link margin for the given data, indicating successful communication between the transmitter and the UAM vehicle. The effect of velocity and altitude on various link parameters and quality of service metrics i.e., latency, were also studied. This study was done while considering different weather attenuations. A loss model was formulated, taking all the losses into account. In the second part, a study on mobility and handover analysis was carried out for a UAM vehicle moving on a straight-line path, using the entropy method and considering three base stations. The signal strength at the UAV from three ground base stations and one satellite base station along the flight path was studied. It was observed that the satellite connection could provide 6G connectivity for only about 250 km on the ground at a time instant. Hence, a larger number of satellites would be required in orbit to provide a 6G terrestrial network to the whole world. The number would depend on the type of service the 6G network aimed to provide. This work contributes to the virtual knowledge bank for researchers working toward the successful implementation of robust communication systems for urban air mobility (UAM). This study highlights the effects of altitude and weather on communication systems. It also proves a methodology for signal handover using the entropy method. This study will be useful for use cases involving UAVs in remote areas, such as medical deliveries, mapping, etc. 8. Future Work This paper studied the link budget for one satellite through its visible time and compared to ground base stations. In the future, various satellite constellations can be studied, adding more indicators to the entropy-weight method for handovers. These indicators can comprise capacity, data speed, and the remaining service time. More link budget parameters, like the bit error rate, can be introduced, which would delve into channel modeling for LEO SATCOM systems. Funding: This research received no external funding. Data Availability Statement: The study’s data are contained within the article. Conflicts of Interest: The authors declare no conflicts of interest. 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This year marks the 100th birth anniversary of Vítězslava Kaprálová (1915–1940), an important representative of inter-war Czech music. She was regarded as one of the most promising composers of her generation by the foremost Czech musicologist Vladimír Helfert. He wrote about her in his seminal study on Czech modern music, Česká moderní hudba, published in 1936. Today, there is no doubt that Kaprálová fulfilled that promise handsomely. Regardless of her untimely passing at the age of 25, she was an exceptionally gifted composer, whose oeuvre has withstood the test of time with admirable ease, proving its relevance for new generations of musicians and music listeners. Despite that her career was cut so short, Kaprálová’s legacy is not a mere torso; her catalog includes a respectable number of forty-five compositions, among which there are remarkable works in all genres of music literature: piano, chamber, orchestral, and vocal music. The cultured environment of Kaprálová’s family and its circle of friends, among whom were some of the finest musicians and scholars of the new Czechoslovak republic, played an important role in the creative development of young Vítězslava. She also benefited from the musical offerings of her native Brno, which in many respects measured up to those of the country’s capital, Prague. Kaprálová’s talent was recognized relatively early and nurtured by her musician parents. Her mother Vítězslava, (born Viktorie Uhliřová, 1890–1973), was a certified voice teacher who studied with Marie Kollarová in Brno and Kristina Morfová at the National Theater in Prague. Kaprálová’s father, Václav Kaprál (1889–1947), studied composition with Leoš Janáček and piano performance with Marie Kuhlová and Klotilda Schäferová in Brno. In 1911, he founded his own private music school in Brno, which grew in reputation and continued to attract generations of aspiring pianists throughout the twenties and thirties. (It is worth noting that one of the faculty, the Czech composer Theodor Schaefer, was Kaprálová’s first mentor in instrumentation.) Kaprál was an outstanding teacher who never stopped educating himself throughout his life; he perfected his skills at composition under Vítězslav Novák (who was to become in due time also the teacher of choice for his daughter) and his piano technique with Adolf Mikeš in Prague and Alfred Cortot in Paris. Throughout the 1920s, Kaprál also devoted much of his time to piano performance: together with his friend Ludvík Kundera, they promoted four-hands repertoire and also performed in concert as a two-piano team. In addition to his performing career, Kaprál worked as a music editor and critic, as a lecturer at Brno’s Masaryk University, and since 1936 as a tenured teacher at the Brno Conservatory, where he taught composition. Music was therefore a natural part of Kaprálová’s life since childhood. It was primarily her mother’s influence, however, that led to Kaprálová’s lifelong passion for art song. Kaprálová’s contribution to the genre has indeed been significant: her songs in general and opuses 10, 12, and 14 in particular represent one of the late climaxes of the Czech art song. The song was the most intrinsic genre for Kaprálová—in it, she combined her passion for the singing voice with her love of poetry. Kaprálová had excellent judgment when it came to poetry: she not only had a penchant for high quality poems (one of her favorite poets was Jaroslav Seifert who at the end of his life won Nobel prize for literature) but she also wrote good poetry. herself (her first song cycle from 1930 and the orchestral song *Smutný večer* [Sad Evening] from 1936 are believed to be set to her own texts). Both parents were very supportive of Kaprálová’s interest in music but had rather practical plans for her: she was to take over her father’s private music school, which he even named in her honor. Kaprálová had her own plans, however; her mind was already set on composition and conducting, and it was this double major program that she chose for her studies at the Brno Conservatory. It is worth noting that she was the very first female student to graduate from the demanding program in the history of this respectable institution. At the Brno Conservatory, Kaprálová studied composition with Czech composer Viliém Petřzelka and conducting with Viliém Steinman and Zdeněk Chalabala, one of the finest Brno conductors and dramaturgs. Kaprálová wrote a good number of compositions during her “Brno period”: one of the earliest was a piano suite that she later orchestrated under the title *Suite en miniature* and assigned it her first opus number. Other noteworthy compositions that followed include Two Pieces for Violin and Piano, op. 3, song cycles *Dvě písně*, op. 4 (Two Songs) and *Jsíky z popele*, op. 5 (Sparks from Ashes), and the remarkable song *Leděn* (January) for higher voice and flute, two violins, violoncello and piano, set to words of Vítězslav Nezval, another great Czech poet. The finest among her compositions from the Brno period are, however, the two-movement *Sonata Appassionata*, op. 6 and the Piano Concerto in D Minor, op. 7, with which Kaprálová graduated from the Brno Conservatory both as composer and conductor. Her graduation concert received highly favorable reviews not only in the regional newspapers but also in major dailies. Among them was the German *Prager Tagblatt* whose reviewer expressed his disappointment over the conservatory’s decision to present only the first movement of Kaprálová’s piano concerto which attested to an extraordinary talent: “Es is zu bedauern, das die Veranstalter nur den ersten Satz des Werkes aufführen liessen, doch auch diese kleine Probe zeigt eine erstaunlich temperamentvolle musikalische Begabung.” In the fall of 1935, Kaprálová was accepted into the Master School of the Prague Conservatory where she continued her double major studies, this time with the best teachers she could find in her own country: composition with Dvořák’s pupil, Vítězslav Novák, and conducting with Václav Talich, a chief conductor of the Czech Philharmonic and Prague’s National Theater. (It is worth noting that in the academic year of 1935/36, when Kaprálová began her studies at the Prague Conservatory, Talich’s master class was opened to only 8 first-year students; even more competitive was Novák’s class with just 5 students.) The Master School and the musical life of the country’s capital provided a stimulating environment for Kaprálová, in which her natural talent, coupled with her strong work ethic, continued to thrive. By joining the Society for contemporary music Přítomnost (The Presence) and as a regular participant of Silvestr Hippman’s musical “Tuesdays” of Umělecká beseda (Artistic forum), she was exposed to contemporary music, both Czech and international. The two societies later also became important platforms for premiering Kaprálová’s new works. During her studies at the Prague Conservatory, Kaprálová composed some of her best known music, such as the song cycle *Navždy*, op. 12 (For Ever) and the art song *Sbohem a šáteček*, op. 14 (Waving Farewell) that she later orchestrated in consultation with Bohuslav Martinů in Paris. Other creations of Kaprálová’s “Prague period” include her remarkable String Quartet, op. 8 and her most popular work for piano solo, *Dobnová preludia*, op. 13 (April Preludes), dedicated to Rudolf Firkušný who brought attention to its qualities by his masterly performance several years later in Paris. But one composition in particular brought her the most public attention—*Military Sinfonietta*, op. 11, Kaprálová’s graduation work, which was premiered by the Czech Philharmonic under the baton of the composer on November 26, 1937 at Lucerna hall in Prague. It was with the sinfonietta that Kaprálová achieved not only wider recognition at home but also abroad when it was performed at the opening night of the 16th season of the ISCM Festival in London on June 17, 1938. The British premiere of the sinfonietta, in which Kaprálová conducted the excellent BBC Orchestra, was transmitted across the ocean to the United States where it was broadcast by CBS (and it was the name of this corporation—Columbia Broadcasting System—that led to an “urban legend” that the concert was broadcast to Columbia in Latin America). According to the reviewer of *Time* magazine, Kaprálová not only fared well at the international competition at the festival but she also became the star of the opening concert, and so “to composer Kapralova, who conducted her own lusty, sprawling composition, went the afternoon’s biggest hand.” Among all the reviews mentioning her performance, Kaprálová would have cherished that of her colleague, Havergal Brian, who in his festival report for *Musical Opinion* wrote: “The first work played and broadcast at the recent festival, a *Military Sinfonietta* by Miss Vitezslava Kapralova of Czechoslovakia, proved an amazing piece of orchestral writing; it was also of logical and well balanced design.” But it is unlikely that she ever read it. Kaprálová travelled to the ISCM festival in London from Paris where she had lived since October of the previous year. She arrived in Paris on a one-year French Government scholarship to advance her music education at the École Normale de musique, initially hoping to continue her double major studies: conducting with Charles Munch and composition with Nadia Boulanger. However, her knowledge of French was not good enough to study with Boulanger; and so she decided to enrol just in the conducting class, because with Munch she could also communicate in German. She also accepted an offer of private consultations with Bohuslav Martinů, who was by then established in France and well respected both in Paris and his native Czechoslovakia. Kaprálová met Martinů in Prague; they became acquainted on April 8, 1937, during Martinů’s brief visit to the capital, where he arrived to negotiate with Václav Talich the details of the premiere of his new opera Julietta at the National Theater. In Paris, Martinů became first Kaprálová’s mentor, later also her friend, and, at the end, her soulmate. From the very beginning, he was generous with his contacts and time; and, besides hours of free consultations, he also opened quite a few doors for Kaprálová. Soon after she arrived in Paris, Martinů introduced her to a circle of composers who were members of Triton, a Parisian society for contemporary music, whose concerts (there were seven to twelve of them per year, concentrated in the period of January–May) Kaprálová diligently attended. He entrusted her with the task of conducting his Concerto for Harpsichord and Small Orchestra, H 246 on June 2, 1938 in Paris, just two weeks before her well-received ISCM Festival appearance. He also facilitated the publication of her Variations sur le carillon de l’église St-Étienne du Mont, op. 16, which he much admired, by La Sirène éditions musicales (whose catalog was bought after the war by Eschig that still list Kaprálová’s original edition in their piano catalog). In the fall of 1938, Martinů spent much time and effort to secure another stipend for Kaprálová so that she could return to France. The rapidly worsening political situation and separation from Kaprálová were the roots of his anxiety projected into his Double Concerto, H 271 for two string orchestras, piano and timpani. Martinů finished this score on the very day of the Munich Agreement. During the same time, Kaprálová continued to work, back home, on her Partita for strings and piano, op. 20, in which Martinů, as he put it himself, “interfered more than he would have liked but both (he and Kaprálová) looked at it as a learning exercise (for Kaprálová).” However, he did not interfere in her Suite rustica, op. 19, commissioned by Universal Edition London, which Kaprálová composed in just three weeks during late October and early November 1938. Neither did he interfere in her Concertino for Violin, Clarinet, and Orchestra, op. 21 (1939), the last movement and orchestration of which Kaprálová later set aside and did not finish. (At the beginning of this millennium, Brno composers Miloš Štědroň and Leoš Faltus were entrusted with the task of finishing the concertino’s orchestration so that it could be recorded for a television documentary about Kaprálová. The concertino had its world premiere on January 10, 2002 in Hradec Králové and its Prague premiere on November 26, 2014—on this occasion, it was performed by Czech Philharmonic at Prague’s Rudolfinum.) The Triton concerts and the thought-provoking discussions with Martinů were some of the elements of Kaprálová’s new environment that further stimulated and accelerated her creative development: during the two years she lived in Paris, Kaprálová produced almost as much music as during the five years in Brno and two years in Prague. The pinnacles of her first “Parisian period” (October 1937–May 1938) include Variations sur le carillon, op. 16 and her (unfinished) reed trio. Another work that Kaprálová composed in Paris during this period, the large orchestral cantata Ilena, op. 15, is important in the context of her own oeuvre. Its musical ideas occupied Kaprálová’s mind as early as 1932. When she finally began working with them, however, she found the music rooted in the post-romantic idiom from which she had already moved; consequently, she felt ambivalent about the composition and finished it only because Martinů valued it. Unfortunately, she did not complete its orchestration. (It was finished only in 2007 by Martin Kostaš, as part of his graduate studies requirements at the Janaček Academy of Performing Arts, so that Ilena could receive its world premiere on May 31, 2007 in Brno.) During her second Parisian period (January 1939–May 1940), Kaprálová was even more productive. Soon after her return to Paris in January 1939, she composed two works honoring the memory of Czech writer Karel Čapek, whose passing during Christmas 1938 was mourned by the nation: the Elegy for violin and piano, and the melodrama Karlu Čapkovi (To Karel Čapek). On March 15, 1939, German armies marched into the streets of Prague. In addition to the occupation of her homeland, Kaprálová had to deal with a personal crisis in her relationship with Martinů; in anguish, she turned to the only solace afforded to her—music. The result was the Concertino for Violin, Clarinet, and Orchestra, op. 21. It reflects much of the composer’s mental state at the worst period of her life; she even scribbled on the score “Job 30:26”—a telling reference to the Book of Job (Yet when I hoped for good, evil came; when I looked for light, then came darkness). The Concertino, with its bold ideas and modern musical language, was to be Kaprálová’s last major work; only two high points were to follow: the song cycle Sung into the Distance, op. 22, and the Deux ritournelles pour violoncelle et piano, op. 25, her last composition. The German occupation of Czechoslovakia changed Kaprálová’s life literally overnight. As a return home was not an option, Kaprálová was now facing the arduous task of earning her own living; she no longer received financial aid from home, (as financial transactions were subjected to new, strict rules), nor her stipend. During the final year of her life, Kaprálová spent much of her precious time on small com- missions in an effort to support herself (one of them was the lively Prélude de Noël, an orchestral miniature that Kaprálová composed for a Christmas program of the Paris PTT Radio). Throughout the spring of 1939, Kaprálová was trying to obtain a scholarship at the Juilliard School so that she could relocate to the United States (in the company of Martinů). Nothing came of the plan, however; and at the end of summer 1939, Kaprálová entirely depended on assistance of several of her friends and a few benefactors (the most generous among them was Jewish-Czech entrepreneur Pavel Deutsch to whom she was introduced by Martinů; she also received two financial contributions from Czech ex-President Edvard Beneš to whom she once dedicated her Military Sinfonietta). Lacking regular income, Kaprálová joined the household of her artist friends who found themselves in a similar position and decided to pool their resources to get through hard times (one of these friends was her future husband Jiří Mucha). She also joined the efforts of the Czech community in Paris that organized activities for and around the newly formed Czechoslovak Army. Soon she became heavily involved: from founding a choir and writing reviews for La Cause Tchécoslovaque to composing music for the radio (Paris PTT Radio), stage (together with Martinů she composed stage music for a theater group) and even screen. (The latter concerned most possibly a commission facilitated by Kaprálová’s friend, film actor Hugo Haas, who at the time worked on two films in France: Mer en flames by director Léo Joannon, in which Haas played a leading role; the film was released in 1945 under the title Documents Secrets; and the film Ils se sont rencontrés dans l’eau, whose script Haas co-authored). In the last months of her life, Kaprálová also resumed her studies at the École Normale (whether she was taking class with Boulanger remains inconclusive), adding to her already busy schedule. In April 1940, less than two months before her death, she married Jiří Mucha. In early May, Kaprálová exhibited the first symptoms of her terminal illness. Since Paris was threatened by German invasion, she was evacuated by Mucha to Montpellier, near his military base in Agde, on May 20. By then Kaprálová was already seriously ill; and, following several weeks of suffering, she succumbed to her illness on June 16, 1940. Despite the amount of research amassed over the decades, there are still many questions in the Kaprálová historiography that remain unanswered. While there is not a single text on the composer that would fail to mention her relationship with married Martinů (some authors do not even shy away from analyzing and evaluating it!), in fact we know very little about it. One thing is certain, however; that it meant a great deal to both of them, and when, in the end, Kaprálová gave it up, she did it out of consideration for her parents, with whom she had lifelong loving relationship. Kaprálová’s relationship with Mucha also raises more questions than answers. Would she have married him under different circumstances than in her difficult situation in 1940? Even the cause of Kaprálová’s death is a mystery, despite the official diagnosis of miliary tuberculosis. It does not fit all that well with the symptoms and the nature of her sudden and acute illness, and is also undermined by the documents found in several private and public archives. The questions that are more important, however, are those concerning the composer’s oeuvre. One remains a complete enigma: Kaprálová’s opus 24. The composer’s correspondence might (or might not) offer some clues: in January 1939, Kaprálová wrote to her friend Rudolf Kopec that her mind had been pre-occupied for some time with musical ideas for a new work she would like to entitle České oratorium (Czech oratorio); in May 1939, she wrote to her parents about her intention to compose Sonatina for violin and piano; in another letter to her parents, from March 1940, she announced that she was about to compose “a smaller thing for orchestra” she would like to entitle Krajiný (Landscapes). Did she reserve the opus 24 for one of these compositions? Had she ever begun composing any of them? We might also never discover another of Kaprálová’s works, the second of her Deux ritournelles, although we know that she at least finished the sketch. Another piece of lost music is Kaprálová’s Two Dances for Piano, op. 23, of which only an unfinished sketch of one dance survived. Perhaps these autographs will resurface one day, as did the orchestral score of Prélude de Noël. But whether they will be found or not, we have been fortunate to have the rest of Kaprálová’s oeuvre: the vital body of works which never fails to surprise and move us. Notes: 2. Czechoslovakia became an independent democratic republic on October 28, 1918. 10. Ibid, 153n95. About the author: Karla Hartl is founder and chair of the Kapralova Society, an arts organization based in Toronto, Canada, dedicated to building awareness of women’s contributions to musical life and to supporting projects that make available, in print and on compact discs, Kaprálová’s music. Hartl is also co-editor of the Kapralova Society Journal and The Kaprálová Companion, the first English monograph on the composer, published in 2011 by Lexington Books and shortlisted the same year for the F. X. Šalda Society Prize for an outstanding editorial effort in art history and criticism. Her new book Dopisy domů (Letters home)—an edited collection of Kaprálová’s correspondence with her parents—will be published this year by Amos Editio in Prague. PÍSNIČKA Little Song (1936) VITĚZSLAVA KAPRALOVÁ (1915-1940) The Kaprálová centenary is an opportunity to highlight some of the accomplishments of our Society since its inception in 1998. There have been many—from initiating and assisting publication and release of Kaprálová’s music to encouraging its performance and broadcast, analysis and research. Over the course of the past sixteen years, we have initiated and assisted a great number of projects. Here are the scores we have initiated and fully supported: Our most notable achievements in brief: 1998–to date: *The Kapralova Society Website*: our award winning site promotes Kaprálová and other women in music. 2000–to date: Articles in *Tempo, Journal of IAWM, Viva Voce, Czech Music Quarterly, Opus musicum*, and *Harmonie*. 2001–to date: Seminal radio documentaries and programs we have assisted: *The Life and Music of Vítězslava Kaprálová* (CBC 2); *Componist van de week: Vítězslava Kaprálová* (Dutch Radio 4 Vara); *Zenske v svetu glasbe: Vítězslava Kaprálová* (Radio Slovenija 3 Ars). 2003–to date: *The Kapralova Society Journal*: our journal of women in music is published twice a year. 2007: *World premiere of Ilena, op. 15*—initiated and financially supported by the Society in partnership with Janáček Academy of Performing Arts. 2011–to date: *The Kapralova Society Award* for the best interpretation of a Kaprálová song is given to participants of the biannual Czech and Slovak art song competition in Montreal, Canada (with semifinals held at the University of Wisconsin). Vítězslava Kaprálová Discography: CDs we helped publish This excellent and generously filled issue does a great deal to establish her credentials as a genuinely fascinating voice in inter-war Czech music... BBC Music Magazine, June 1999. [A] moving testimony to a substantial creative personality who had already hit her stride before her career was so cruelly cut short. Tempo, October 2000. Discoveries aplenty here ... Well worth the quest you will need to make if you want to find this treasurable CD... Musicweb.uk, October 2003. In her short 25 years, Czech composer Vítežslava Kaprálová amassed an astonishingly original output that would be the envy of any composer three times her age... All Music Guide, July 2005. Yes, of course, it would be fascinating to know what Kapralova would have become had she survived to full maturity - but more to the point, there can be no question that the music she actually left is more than worth getting to know. Records International, August 1999. Une artiste d'exception... Diapason, May 2004 Kapralova est pour le lied tchèque ce que Duparc est pour la mélodie française. Une redécouverte capitale. AbeilleMusique.com Some of the most purely beautiful music I have heard in a long while. Musicweb.uk One of the best CDs in the genre of 20th century art song repertoire recordings. IAWM Journal, Fall 2004 There are some real treasures here and for anyone interested in 20th-century Czech music, a fresh perspective on the post-Janacek era. BBC Music Magazine, March 2004 Kapralova's group of songs Forever would be a remarkable achievement for any composer, let alone one in her early twenties. Fanfare Magazine Both Burešová and Cheek display expertise in portraying the many intricate and complicated facets of this hauntingly beautiful vocal music, and their CD is a must-have for anyone interested in the music of Kapralová. Kapralova Society Journal, Fall 2011 Recorded in July 2007 at the Performing Arts Center, Purchase, New York. If you are looking for highly sophisticated piano music rich in texture, clarity and depth, look no further. About.com The piano and violin-and-piano music here is richly melodic, highly chromatic, and bursting with invention. American Record Guide, 2008 Kapralova’s music displays a remarkable mastery of form and harmony, and radiates youthful spontaneity, lyrical tenderness, and passionate intensity. Strings Magazine, Nov. 2008 Kaprálová was one of the major female composers in history, despite her short time on earth; this Koch disc does her music considerable justice and serves as a strong introduction to Kapralová’s music. Allmusic.com Add this to your select discography of a composer whose early death deprived Czechoslovakia of a burgeoning talent. Musicweb.uk I have no doubt that this release will not only please Kapralova's enthusiasts but also add many others to her following. IAWM Journal, Fall 2008 This recording is an important milestone in Kapralova's discography and testifies to the memory of a brilliant mid-twentieth century composer. Amazon.com The recording is strong and the performances sensitive and completely committed. Musicweb.uk Recorded live at the House of Art in Zlin in November 2010 and at the Congress Center Zlin in June 2011. The 2011 compact disc recording featuring four of Vítezslava Kaprálová's piano works is an important addition to the growing oeuvre of CDs showcasing Kaprálová's compositions. Not only does this recording contain representative works from the span of her career, but it also marks the first recording of her Piano Concerto in D Minor. The entire CD is expertly played by pianist Alice Rajnohová and matched in passion and precision by the Bohuslav Martinu Philharmonic Orchestra under the direction of Tomáš Hanus. Kapralova Society Journal, Fall 2012. This CD release of the Czech Radio is worth buying for Kapralova’s Concerto in D-Minor, op. 7 (1934–1935) alone. Kapralova graduated with the concerto from the Brno Conservatory in 1935, and while the work is rooted primarily in the late romantic idiom, its energetic and passionate score is full of fresh and inspiring ideas. The works receives a sensitive performance from both the soloist and the orchestra in front of live audience. Amazon.com [Concerto is] Amazing! Sounding romantic at the opening but quickly developing to more 20th Century astringency. A touch of Hindemith, particularly in the second movement. Most enjoyable, the performance bringing out the best. “Entusiastico” indeed! YouTube, 2013. Recorded in April 2007 in the Margaret Comstock Concert Hall at the University of Louisville School of Music, Louisville, Kentucky. The most important reason to add this to your recording shelf is the opportunity it affords the listener to encounter the music of four gifted women composers. With its superb performances, this disk is an excellent step in the right direction. Journal of Singing, Nov./Dec. 2009 Recorded in November 2009 at the Czech Radio Ostrava. The three composers also came very close together in these works intellectually - to the point that the way their quartets are performed and combined on this recording gives an impression of a "through-composed" triptych. [...] The youthful string quartet of Kapralova enchants the listener from the first measures by its freshness and vitality. The Škampa Quartet also lives up to its reputation as one of the most renowned Czech quartets; theirs is a highly sophisticated and sensitive performance that attests to their extraordinary musical imagination. Czech Music Quarterly, 1/2013 This disc will particularly interest those intrigued by the links between the three composers. The disc opens with a quartet by Vaclav Kapral, a pupil of Janacek whose influence is apparent in this engaging work. Martinu’s 5th Quartet is already well represented in the catalogues but this new recording brings us a fresh interpretation from the admirable Škampa Quartet. Kapralova’s own quartet pre-dates her meeting with Martinu. It has been recorded before but this performance presents a more authentic edition of the score, restoring previous cuts. It shows that at the time of its composition in 1936, Kapralova’s idiom had evolved beyond the influence of her father and was developing a distinctive and appealing voice of its own. Martinu Revue 1/2013. Shortlisted for the 2011 F.X. Šalda Prize. The prize of a private foundation based in Prague, Czech Republic, is awarded for outstanding editorial efforts and important contributions to art history and criticism.
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Relational Ethics Thaddeus Metz and Sarah Clark Miller Introduction When we consider long-standing and widely held ethical perspectives, we can identify a strain that is fundamentally relational, that is, that conceives of moral status, right action, or good character as constituted by beneficent ties or other bonds of sharing (see benevolence). In this essay, we first sketch the basics of such an approach and provide reason to think it is indeed distinct from other, individualist or holist, approaches to ethics. Then, we consider salient instances of relationalism from three major moral traditions that have been particularly influential in recent English-language philosophical literature: Confucianism in East Asia, ubuntu in sub-Saharan Africa, and feminist and care perspectives in Anglo-America-Australasia. Upon expounding the essentials of each approach, we indicate some topics that would be suitable for future research. Nature of and Background to Relationalism Although relational conceptions of morality have existed for many centuries, indeed probably long before alternative views, it is only lately that relationalism has been articulated as a distinct kind of ethic in English-speaking philosophy (see, e.g., Austin 2008). Recent awareness of it has been occasioned mainly by twentieth-century challenges to characteristically male and Western approaches to normativity. On the one hand, some feminists have argued that girls and women are more likely to adhere to a relational ethic, often one of care (perhaps for reasons of nurture as opposed to nature). On the other hand, greater intercultural exchanges have made English speakers more aware of African and Asian moral philosophies, which tend to place familial bonds at the core of how to live. Sandra Harding (1987) was one of the first to identify relationality as a common thread among those questioning androcentrism and Eurocentrism. Very broadly speaking, whereas contemporary white male moral philosophers and professional ethicists have tended to maintain that either freedom or happiness is the “mother of all values,” in the words of Daniel A. Bell and Yingchuan Mo (2014), non-white and non-male ones have largely been the ones to maintain that it is, instead, either care, community, or harmony. There have, of course, been exceptions. Those working in the Christian tradition would plausibly deem the commandment to love one’s neighbor as oneself to be an instance of relationalism; and the writings of the young Karl Marx are naturally read as expressing the view that human nature *qua* social is something that demands to be developed (see *Marx, Karl*). For example, Marx writes: > Since human nature is the true communal nature of man, men create and produce their communal nature by their natural action; they produce their social being which is no abstract, universal power over against single individuals, but the nature of each individual, his own activity, his own life, his own enjoyment, his own wealth … [T]o say that man alienates himself is the same as to say that the society of this alienated man is a caricature of his real communal nature. (2000 [1844]: 125) Western Marxists in the twentieth century were substantially influenced by this ethic, sometimes characterized as “communitarian” (*see* Communitarianism). One could also mention the ethics of Baruch Spinoza, Martin Buber, and Emmanuel Levinas (whose work is, however, primarily phenomenological rather than normative) in the Continental philosophical tradition. To clarify the nature of a relational ethic, contrast it with other, perhaps more familiar perspectives (this and the next few paragraphs borrow from Metz 2012: 389–90). First off, an individualist account of morality is the view that properties intrinsic to an entity ground the capacity to be wronged or to be the object of a direct duty, where dutiful action is roughly what either promotes or honors these properties. An intrinsic property, as understood here, is a feature that is internal to an individual and includes no essential connection to any other being. Influential forms of individualism include the views that moral status and right action are at bottom a function of being in the agent’s interests (egoism), being a living organism (biocentrism), exhibiting the capacity for autonomy or rationality (Kantianism), and having the capacity for preference dis/satisfaction or for dis/pleasure (utilitarianism). At the other extreme is a holist or corporatist account of morality, the view that the bearer of moral status is a group of some kind and that morally appropriate behavior is what develops or respects it. A group, here, is a discrete collection of entities that are close to, similar to, or interdependent with one another. Those who ascribe moral standing to peoples or species are holist in this way, with another clear example being Aldo Leopold’s influential land ethic, roughly according to which an act is right insofar as it tends to sustain an ecosystem. In contrast to both individualism and holism, relationalism is the idea that moral status is constituted by some kind of interactive property between one entity and another, which property warrants being realized or prized. It therefore stands “in between” individualism and holism. Similar to individualism, a relational account implies that moral status can inhere in beings as they exist apart from their membership in groups. According to a relational theory, something can warrant moral consideration even if it is not a group or a member of one, or for a reason other than the fact that it is a member. Similar to holism, though, a relational account accords no moral status to an entity merely on the basis of its intrinsic properties. A relational theory implies that a being warrants moral consideration only if, and because, it exhibits some kind of other-regarding property, one that is typically intensional or causal. In addition to English-speaking normative ethics of late having been noticeably informed by relational approaches, so too has applied ethics. This is particularly true in healthcare ethics (Bergum and Dossetor 2005; Woods 2012) and environmental ethics (Hourdequin and Wong 2005; Behrens 2014). In the rest of this essay, we survey three instances of relationalism that are particularly prominent in normative philosophical thought appearing in English. We proceed in largely chronological order, from the earliest to the most recent. The Confucian Tradition Confucianism has a complex, 3,000-year-old written history, and remains the dominant ethical worldview in China and some neighboring countries in East Asia (see Confucian Ethics). According to one major strand of Confucian thought, at least as interpreted lately, (nearly) all key moral values are ultimately a function of harmonious relationships (Fan 2010; Bell and Mo 2014; Li 2014). Aesthetic analogies with making music and cooking food are frequently invoked to explain what harmony is. Basically, it is a matter of different elements coming together, where differences are not merely respected, but also integrated in such a way that the best of them is brought out and something new is created (Ihara 2004; Li 2014). By this construal, for a person to relate harmoniously is essentially neither to become the same as others, nor to agree with them. Doing so instead presupposes the existence of a variety of interests and standpoints, where they are unified – but not made uniform – in such a way that is good for all. To illustrate the Confucian conception of harmony in more detail, consider the famous “Three Bonds,” the human relationships in which, and by which, one is particularly expected to realize harmony, namely, between ruler/minister (sovereign/subjects), father/son (parents/children), and, traditionally, husband/wife. The hierarchical nature of the Three Bonds is palpable; essential to them is the idea of higher and lower positions. Sometimes the thought is that unequal relationships are most likely to produce harmony separately and in the long run, while at other times it is that harmony is to be realized within them. Although there have been traditional strains of Confucianism interpreting the hierarchy in terms of unconditional obedience on the part of the inferiors, most these days instead stress the idea that it should involve reciprocity, a relationship in the interests of both parties to it and hence comprising action informed by sympathy, compassion, generosity, and the like. Those in a superior position, while having more responsibility, are obligated to act for the sake of those in a lower one, while inferiors are expected to show respect for superiors, which need not mean unquestioning deference and can include remonstrating. In addition, most contemporary advocates of Confucianism, at least those writing in English, aim to avoid sexism in the family (e.g., Li 2014: 101–16). So, Confucianism does not justify absolute monarchy or patriarchal whim, although it does prescribe a division of labor, with managerial functions going to rulers and heads of households who should be qualified by their age, experience, education, and virtue. The most important manifestation of a harmonious relationship, both in itself and as a means to the realization of other virtues, is between parents and their children. The phrase “filial piety” is used to sum up the virtue of relating to one’s parents; as one scholar remarks: “For Confucius, the paramount example of harmonious social order seems to be xiao (filial piety)” (Richey, n.d.; see Confucius). The parent/child relationship is expected to be the most intense exemplification of harmony. And it is also meant to serve as a training ground for relating to human beings in general, so that one develops (less intense) benevolent inclinations toward strangers. Even if contemporary Confucianism aims to leave sexism behind, readers might wonder whether it is sufficiently egalitarian. Although it would permit an elderly woman to serve as the head of a household, its meritocratic orientation would seem to exclude the idea of joint rule among adults on all major issues in a family. And then there appears to be little scope for a democratic polity at the level of government, an alleged bullet that many Confucian political philosophers are interestingly happy to bite (e.g., Bell and Li 2013). Another concern is whether Confucianism is sufficiently impartial (see impartiality). Although a common view these days among Confucians is that everyone matters morally insofar as they are capable of virtuous character, there is an irreducible partialism to Confucianism. One is expected to care most for one’s family and to extend one’s concern in proportion to the strength of one’s affective ties. One problem, here, is that this appears to apply to those in charge of governments and businesses as well (but see Fan 2010: 23, 30–2, 34–7), and a second is whether there is enough ground for cosmopolitan concern for the suffering of strangers far away. The African Tradition In contrast to Confucianism, the sub-Saharan philosophical tradition has largely been an oral one, with many written texts appearing only after the demise of European colonialism, which began in the late 1950s. Like most self-described “African philosophers” these days, we limit ourselves to recent, literate philosophical expressions grounded on values and norms that have been salient in traditional African ways of life for at least several centuries. In addition, we focus on those texts that take relationality to be fundamental, acknowledging that there are others who deem it to be of merely instrumental value (for the realization of, say, well-being). For most thinkers inspired by indigenous Africa, one’s basic goal in life should be to realize human excellence or what is called “ubuntu” in the famous vernacular in South Africa (see African ethics). The familiar idea is that there is a higher, distinctively human part of our nature as well as a lower, animal part, and that we ought to strive to develop the former instead of the latter. Less familiar is a view common among traditional black African peoples about how to develop humanness or to become a real person, namely, by living communally with others (often the language of “harmony” is also used, but, to avoid conflation with the Confucian use of it, we set that term aside). To begin to understand what a communal relation amounts to in this tradition, consider remarks from some African thinkers. The Nigerian philosopher Segun Gbadegesin says that for traditional Yoruba morality, “Every member is expected to consider him/herself an integral part of the whole and to play an appropriate role towards achieving the good of all” (1991: 65). Gessler Muxe Nkondo, a South African public intellectual, says: “If you asked ubuntu advocates and philosophers: What principles inform and organise your life? … the answers would express commitment to the good of the community in which their identities were formed, and a need to experience their lives as bound up in that of their community” (2007: 91). The Kenyan historian of African philosophy Dismas Masolo highlights what he calls the “communitarian values” of “living a life of mutual concern for the welfare of others, such as in a cooperative creation and distribution of wealth … Feeling integrated with as well as willing to integrate others into a web of relations free of friction and conflict” (2010: 240). These and many other construals from different parts of Africa about what it is to commune with others suggest two recurrent themes (see Metz 2012: 393–5). On the one hand, there is a relationship of sharing a way of life, a matter of considering oneself a part of the whole, experiencing life as bound up with others, and feeling integrated. On the other, there is reference to a relationship of caring for one another’s quality of life, that is, achieving the good of all, being committed to the good of others, and being concerned for others’ welfare. The combination of sharing a life with others and caring for them is basically what English speakers mean by “friendliness” or “love” in a broad sense (see FRIENDSHIP; LOVE). Hence, one can sum up one major swathe of traditional African thought about how to live by saying that one’s highest-order end should be to live a genuinely human way of life, which one does by prizing communal – that is, friendly – relationships. Traditionally speaking, important agents with whom one ought to relate communally are spiritual beings, especially ancestors, wise founders of a clan who are thought to have survived the deaths of their bodies, to have continued to reside on earth, and to provide guidance to human family members (e.g., Paris 1995; Murove 2007). However, many contemporary interpreters of African morality favor a more secular rendition of the proper entities with which to commune. Like Confucianism, one’s own communal or friendly relationships matter most for typical African approaches to morality; “family first” and “charity begins at home” are commonly expressed, in order to indicate a principled priority going to actual ties of which one is a part. However, it is also a salient element of sub-Saharan thinking about morality to deem all human beings to have a dignity or to be part of a human family. It therefore includes an important impartial dimension, with hospitality to visitors from afar being a salient theme in this tradition, unlike in the Confucian. One issue meriting debate with regard to a characteristically African approach to morality is that it seems to leave little space for individual self-determination. Obligations to help other people, especially family members, are typically deemed to be quite weighty, with more than a few sub-Saharan ethicists doubting that there is a category of the supererogatory. In addition to a duty to engage in mutual aid, there is also an obligation to participate in the life of one's society, so that remaining isolated would likely be deemed immoral, even if one were not harming others. Still more, innovative behavior on the part of individuals seems to be discouraged by this sort of ethic, insofar as long-standing practices that are central to a people's self-conception have substantial moral weight. And where traditional practices are patriarchal, the requirement to share a way of life becomes even more problematic. Contemporary African philosophers often seek creative ways to avoid sexist implications of their views, with some doing so by suggesting that truly sharing a way of life means freely choosing it. The Feminist and Care Traditions As a concept, relationalism has found a consistent home in feminist ethics (see feminist ethics). While within this tradition an ethic understood as relational is most readily identified with care ethics, it is significant for other methodological approaches within feminist philosophy, too. In other words, within feminist philosophy, while central to care ethics, relational ethics is not exclusive to it. Care ethics, however, will be our primary focus in this section (see care ethics). Care theory can be of a sentimentalist (Slote 2007), virtue ethical (Halwani 2003), or deontological (Miller 2012) variety, with accompanying subtle shifts in their respective take on relational ethics. In this section, the aim is to characterize the moral features typical of care ethics as a whole, with a specific emphasis on the ways in which care ethics is relational. Historically speaking, the late 1980s saw the rise of relational ethics as a prominent concept within feminist thought, initially in conjunction with the work of psychologist Carol Gilligan (1982), educator Nel Noddings (1984), and philosopher Sara Ruddick (1989). In this context, a relational ethics of care referred to “a feminine view … in the deep classical sense – rooted in receptivity, relatedness, and responsiveness” (Noddings 2013: 2). The initial association between relational ethics and the feminine did not stand the test of time, as Noddings’s change to the title of her 1984 landmark book, Caring, indicates. Heeding objections regarding a latent essentialism in the assumed connection between care and the feminine, Caring’s subtitle, A Feminine Approach to Ethics and Moral Education, became, in 2013, A Relational Approach to Ethics and Moral Education. In explaining the change, Noddings writes: “I think critics are right … to point out that the connotations of ‘feminine’ are off-putting and do not capture what I intended to convey. Relational is a better word. Virtually all care theorists make the relation more fundamental than the individual” (2013: xiii). Thus, while initially arising from an interest in the previously underappreciated moral insights of women’s experiences, care ethics is open to and relevant for all, regardless of gender. An ethic can be said to be relational in several distinct ways, including its content, its account of right action, and the grounding of its normativity. Here we will consider five such relational features. First, the subject matter of an ethic can be relational. More so than probably any other ethical philosophy, at least in the West, care ethics concentrates on our relations with others. Relationships function as legitimate and primary matters of moral inquiry and moral significance. Moreover, while in many moral theories the individual is the ultimate unit of moral concern, in care ethics relationships themselves are taken to be at least the primary, if not the most fundamental, units of moral concern, as Noddings claims (see above). What exactly does such an assertion mean? In the more usual case in which individuals function as the ultimate units of moral concern, they serve as nothing short of the primary point of orientation for a moral theory. For example, many moral theories focus on the well-being of the individual or on the way in which each individual has dignity and is deserving of respect. While not all moral concepts centered on the individual transfer seamlessly to a relational perspective (it is not entirely clear, for example, what it would mean to refrain from violating the rights of a relationship), many do: the I becomes we as we carefully weigh the consequences of actions for our relationships, consider how to respect our communal bonds, and aim to foster virtuous relationships that are trusting and generous. This shift in perspective is effected when we take our relationships and relationality as the starting points for moral theory. Doing so transforms our view of the nature of an individual moral agent: the independent, ideally autonomous, and rational agent who stars in much of modern moral philosophy morphs into an interdependent, vulnerable, and emotional agent. The idea of the individual is reconceived as the self-in-relation, a concept that highlights both the fundamentally relational nature of human social ontology, as well as the constitutive importance of relationships for establishing moral agency in the first place. A second main relational feature of care ethics is its account of right action. This approach to right action arises from a paradigm of personal relationships, that is, the caring relation, making care an ideal, rather than a non-ideal, moral consideration (Mills 2009). The ideally caring relationship forms a basis for answering the question, “What ought I do?” In the caring relation, one person cares for another, who receives care. It is a relationship characterized by attentiveness and empathy (see empathy) – a mode of receptivity and openness to another’s affective states that allows one to feel with her and understand her emotions, needs, and interests (see needs). It is also characterized by sympathetic responsiveness through the actions of the caregiver that support the well-being and interests of the one in need (see sympathy) and through the responsiveness of the person in need as she acknowledges receiving care. When done well, care can involve a merging of interests in which the caregiver comes to share the interests of the one in need. Thus, right action is action that demonstrates these various features of caring – action that builds and sustains both the relationship with and the agency and well-being of the cared for. Morally impermissible action is relationship-withering action – action that involves insensitivity to the cared for, “responsiveness” that runs roughshod over her needs and interests, and a general disinterest in preserving and furthering the relationship. For care ethicists, the emotions play a prominent role in moral relations, thoroughly influencing moral decision-making, which, for many other moral philosophies, is primarily a process of moral reasoning. This centrality of the emotions to moral life comprises a third feature of care ethics. The emotions – and especially those tied to caring well – instruct our moral decisions, motivate our continuing interest in caring, and guide us in enacting ideal moral relations. The multipronged significance of the emotions is tied to another relational emphasis of care ethics: the moral permissibility of partiality. For many, though not all, care ethicists, it is morally permissible for those to whom we feel special ties, such as family, friends, neighbors, etc., to receive the lion’s share of our moral attention. Impartiality, a moral requirement of other leading moral theories, including deontology and consequentialism, is not a requirement for the ethics of care. Care ethics offers a distinctive approach to moral perception – one that is fully informed by the moral significance of context and particularity – a fourth feature of the ethics of care. The degree of relationalism underlying the closely connected notion of moral salience is notable. Generally speaking, it is through our moral perception that we determine what has moral salience in any given situation, which then ultimately informs our moral judgments. Those with a caring mode of moral perception determine the moral salience of a situation by discerning both the intricate particularity of the moral agents and patients involved, as well as the wider context (relational and otherwise) in which they are situated. Moral perception, thus rendered, influences how we identify what is morally salient in the first place, what information we include in moral decision-making and moral judgment, and even how adeptly we respond to the specific scenario of those in need for whom we care. The fifth and final relational feature concerns the source of moral responsibility for care ethics, that is, the reason in light of which we must respond to others in the first place. Historically, moral theorists often tied this reason to what they took to be distinctive human capacities, such as rational autonomy, to name one favorite. Care ethicists have been less sanguine about naming a foundational reason why we must care for others, perhaps because in a caring relation to give a reason for caring is to give one reason too many, to evoke Bernard Williams (1976: 214). Thus the answer to the question of what constitutes the normative foundation of care ethics has remained elusive. The reluctance to address this point, if it can be so characterized, might also stem from the connected notion that in doing so, care ethicists would tread dangerously close to articulating a principle of care. Most care ethicists have a somewhat allergic reaction to moral principles, feeling that the application of such principles could codify the responsive emotional quality of good care into a regimented, cold decision procedure (think of the standard application of Kant’s Categorical Imperative or Mill’s Greatest Happiness Principle), hence flattening the rich emotional landscape of moral life. This concern is not without merit. And yet the question remains. There are several possible answers that care ethicists might offer on this point. Some ground moral responsibility in recognition of facets of our shared finitude. More specifically, care ethicists cite our relation with one another as mutually vulnerable and needy, as well as interdependent, as the grounding reasons of moral responsibility (Mackenzie et al. 2014). With this final point in place, we can see that care ethics is a relational ethics the whole way down, so to speak; the very normative foundation of care ethics is relational. See also: AFRICAN ETHICS; BENEVOLENCE; CARE ETHICS; COMMUNITARIANISM; CONFUCIAN ETHICS; CONFUCIUS; EMPATHY; FEMINIST ETHICS; FRIENDSHIP; IMPARTIALITY; LOVE; MARX, KARL; NEEDS; SYMPATHY REFERENCES Bergum, Vangie, and John Dossetor 2005. Relational Ethics. Hagerstown, MD: University Publishing Group. **FURTHER READINGS**
Can yield variability be explained? Integrated assessment of maize yield gaps across smallholders in Ghana Article in Field Crops Research · April 2019 DOI: 10.1016/j.fcr.2019.03.022 0 CITATIONS 99 READS 8 authors, including: Marloes van Loon Wageningen University & Research 12 PUBLICATIONS 162 CITATIONS C. Akiotsen-Mensah University of Ghana 44 PUBLICATIONS 63 CITATIONS Michiel van Dijk International Institute for Applied Systems Analysis 54 PUBLICATIONS 343 CITATIONS P. Reidsma Wageningen University & Research 100 PUBLICATIONS 1,805 CITATIONS Some of the authors of this publication are also working on these related projects: - Checks and Balances for RUE assessment: reducing yield gaps while accounting for nutrient- and water fluxes across spatiotemporal scales. View project - Maize yield gaps in Africa View project All content following this page was uploaded by Marloes van Loon on 14 April 2019. The user has requested enhancement of the downloaded file. Can yield variability be explained? Integrated assessment of maize yield gaps across smallholders in Ghana Marloes P. van Loon,⁎ Samuel Adjei-Nsiah, Katrien Descheemaeker, Clement Akotsen-Mensah, Michiel van Dijk, Tom Morley, Martin K. van Ittersum, Pytrik Reidsma Plant Production Systems, Wageningen University, P.O. Box 430, 6700 AK, Wageningen, the Netherlands Forest and Horticultural Crops Research Centre, School of Agriculture, University of Ghana, Legon, Ghana Wageningen Economic Research, Wageningen University & Research, Alexanderveld 5, 2585 DB, The Hague, the Netherlands ARTICLE INFO Keywords: Yield gaps Yield potential Integrated assessment Smallholder farms Crop modelling Crop experiments Farm household survey ABSTRACT Agricultural production in Ghana should more than double to fulfil the estimated food demand in 2050, but this is a challenge as the productivity of food crops has been low, extremely variable and prone to stagnation. Yield gap estimations and explanations can help to identify the potential for intensification on existing agricultural land. However, to date most yield gap analyses had a disciplinary focus. The objective of this paper is to assess the impact of crop management, soil and household factors on maize (Zea mays) yields in two major maize growing regions in Ghana through an integrated approach. We applied a variety of complementary methods to study sites in the Brong Ahafo and Northern region. Farm household surveys, yield measurements and soil sampling were undertaken in 2015 and 2016. Water-limited potential yield (Yw) was estimated with a crop growth simulation model, and two different on-farm demonstration experiments were carried out in 2016 and 2017. There is great potential to increase maize yields across the study sites. Estimated yield gaps ranged between 3.8 Mg ha⁻¹ (67% of Yw) and 13.6 Mg ha⁻¹ (84% of Yw). However, there was no consistency in factors affecting maize yield and yield gaps when using complementary methods. Demonstration experiments showed the potential of improved varieties, fertilizers and improved planting densities, with yields up to 9 Mg ha⁻¹. This was not confirmed in the analysis of the household surveys, as the large yield variation across years on the same farms impeded the disclosure of effects of management, soil and household factors. The low-input nature of the farming system and the incidence of fall armyworm led to relatively uniform and low yields across the entire population. So, farmers’ yields were determined by interacting, and strongly varying, household, soil and management factors. We found that for highly variable and complex smallholder farming systems there is a danger in drawing oversimplified conclusions based on results from a single methodological approach. Integrating household surveys, crop growth simulation modelling and demonstration experiments can add value to yield gap analysis. However, the challenge remains to improve upon this type of integrated assessment to be able to satisfactorily disentangle the interacting factors that can be managed by farmers in order to increase crop yields. 1. Introduction Agricultural production in sub-Saharan Africa (SSA) should triple to fulfil the estimated food demand in 2050 (Godfray et al., 2010; van Ittersum et al., 2016). In Ghana, as in much of SSA, this is a challenge as yields of food crops are low and productivity is extremely variable and has been stagnating in many areas over recent years (MOFA, 2010). For example, it was estimated that on average, 20% of maize (Zea mays) yield potential is achieved across Ghana (GYGA, 2018). In addition, due to climate change, the frequency of drought in SSA is expected to increase (Hulme et al., 2001; IPCC, 2014) and as a result, Ghana’s dependence on rain fed agriculture for food production would become more precarious (De Pinto et al., 2012). Sustainable agricultural intensification is recognised as one of the main strategies for increasing food production (van Ittersum et al., 2016), especially in densely populated areas where the potential to expand agricultural land is limited. Moreover, as experienced in Ghana, available land for farming is becoming increasingly scarce due to population increase and competition with other economic activities (Braimoh and Vlek, 2006). Yield gap estimations and explanations provide important information on the potential for intensification on existing agricultural land (Laborte et al., 2012; Lobell et al., 2009; Van Ittersum et al., 2013), and provide a starting point for ensuring that intensification happens in a sustainable matter. The yield gap \( Y_g \) is the difference between actual farmers’ yield \( Y_a \) and yield potential under irrigated \( Y_p \) or rainfed \( Y_w \) conditions. \( Y_p \) is yield determined by growth-defining factors, i.e. plant characteristics, temperature, \( \text{CO}_2 \), and solar radiation (Evans, 1996; Van Ittersum and Rabbinge, 1997). Besides the growth-defining factors, \( Y_w \) is also influenced by soil type, field topography and precipitation (Evans, 1996; Van Ittersum and Rabbinge, 1997). A review of yield gap explanation factors indicated that for SSA, fertilization (timing and amount) often explained the yield gap for various crops (Beza et al., 2017). Other analyses found that improving fertilization alone could narrow the yield gap in SSA by 50% (Mueller et al., 2012). In Ghana, increased fertilizer use has been shown to enhance yields, but, a low soil fertility status can limit the yield response (Chapoto et al., 2015). In practice, current fertilizer use in Ghana is low (i.e., on average 5 kg N ha\(^{-1}\)) (FAO, 2018) and this has been explained in terms of the risk associated with relatively high costs of fertilizer in relation to the uncertainty in yield gains (Agyare et al., 2014; Sileshi et al., 2010). Besides fertilization, additional biophysical and socioeconomic factors also contribute to the yield gap. This complexity has been confirmed by studies showing that factors affecting the yield gap can vary substantially between farms (Kihara et al., 2015; Mueller et al., 2012; Silva et al., 2018). Moreover, a body of work analysing technical efficiency of maize producers in Ghana also points to numerous, and varied factors explaining yield differences among farmers, including seed input, agrochemicals, fertilization, labour, farm experience, age, education and access to credit (Appendix A). The diversity of smallholder farming systems and households in SSA (e.g. in terms of soils, risk perceptions, wealth) (Affholder et al., 2013; Berre et al., 2017; Tittonell et al., 2010, 2007; Tittonell and Giller, 2013) compel one to dig deeper into yield gap analysis. However, until now, most yield gap analyses of Ghana are based on either surveys (Abdulai et al., 2013; Addai and Owusu, 2014; Kuwornu et al., 2013), modelling (Mueller et al., 2012) or field experiments (Sileshi et al., 2010). Integrated assessments, using multiple methods at multiple levels, might be able to unravel some of the complexity experienced by farmers. Causes of yield gaps have been analysed through models and surveys in different countries (Rattalino Edreira et al., 2017; Silva et al., 2017, 2018), but up to now these approaches were not combined with field experiments. Combining the approaches and different levels of analysis (including field and farm level) is expected to result in relevant insight into the factors explaining yield gaps. Our main objective in this study is therefore to assess the impact of crop management, soil and household factors on maize yields and yield gaps in Ghana by integrating different methods and data sources. Subsequently, we aim to identify options that could be used to mitigate yield gaps. We focus on maize production by smallholder farmers because in Ghana agriculture is mainly carried out by smallholder farmers (Chamberlin, 2008) who widely produce maize, a major food crop in the country (Angelucci et al., 2013; Wood, 2013). Fig. 1. a) Map of Ghana indicating the location of Nkoranza and Savelugu municipalities in the Brong Ahafo and Northern regions, respectively; b) Location of surveyed villages in Savelugu municipality; c) Location of surveyed villages in Nkoranza municipality. 2. Material and methods 2.1. Study sites The study was conducted in 2015, 2016, and 2017 growing seasons in Nkoranza and Savelugu municipalities, located in two different agroecological zones (AEZ) that represent major maize growing regions in Ghana and across large areas of West Africa (Fig. 1). Each AEZ has markedly different agroecological and market conditions. Nkoranza, located in the Brong Ahafo region of Ghana, is in the forest/savanna transitional AEZ (Fig. 1a). The region experiences a major rainy season commencing in April and a minor rainy season commencing in September (Fig. 2a). This region accounts for the highest proportion of maize production within the country (MOFA, 2015). Data collection in Nkoranza was carried out in three villages, namely, Bibiani (7.55°N, 1.77°W), Dandwa (7.52°N, 1.73°W), and Broahohuo (7.48°N, 1.73°W), which are located eight, five and 12 km away from Nkoranza, the municipal capital, respectively (Fig. 1c). Savelugu, located in the Northern region, is in the southern Guinea savannah AEZ and has a single rainy season commencing in May and ending in October (Fig. 2b). Data collection was carried out in three villages, namely, Nyatua (9.63°N, 0.77°W), Kpendua (9.66°N, 0.89°W) and Langa (9.57°N, 0.89°W), which are located six, eight and 11 km away from Savelugu, the municipal capital, respectively (Fig. 1b). The villages in both municipalities were selected in consultation with the local agricultural extension agents based on the extent of maize cultivation in the community, proximity to the main capital, i.e. the market, and for representativeness. 2.2. On-farm data 2.2.1. Household survey Farm household surveys were conducted during the 2015 and 2016 maize growing seasons. The same households were surveyed in both years (as yields and management differ per year), 15 per village and 90 households in total. The selected households represented different wealth statuses within each of the villages. Wealth status was based on, among others, household size, livestock herd size, and farm area. Individuals within the village, with an overview of all households, assisted in categorising the households into low-, medium- and high-wealth categories. Depending on the proportion of households in the three wealth categories in each village, three to eight households within each category were selected to constitute 15 farms per village. In Nkoranza, each of the selected households were surveyed three times during consecutive maize harvests. Households were visited during the 2015 minor season and both the major and minor seasons in 2016. In Savelugu the survey was conducted during harvest in November in both 2015 and 2016. The survey included information on the household’s socio-economic characteristics, farm characteristics and field-level maize management (Appendices C, D). Questions related to the household included topics on household composition, schooling, farm experience, labour availability, household assets, and off-farm income. Questions related to the farm included farm structure, livestock herd size, and crops grown on each of the plots. Furthermore, questions on management regarding the maize plots included variety, sources of seed, labour, agrochemical inputs and use of maize residues. After the first round of the household survey, the questions related to household characteristics were excluded as we assumed these factors did not change between seasons. 2.2.2. Maize yield measurement Maize yields were measured in each maize plot belonging to each of the surveyed farmers. In each maize plot, three random areas measuring five by five metres, were selected for sampling. Maize plants were counted to determine plant density at harvest and, cobs were removed, de-husked and marketable cobs counted and weighed. From the marketable cobs, ten were randomly selected, weighed and oven-dried at 70 °C for two days to determine the dry matter content. Maize grain yield data are presented with a correction for moisture content of 12%. 2.2.3. Soil sampling and analysis Soil was sampled from every maize plot in the household survey. Soil samples were randomly collected at four sites within each field. Samples were taken from 0 to 20 cm depth in a y-shaped manner. These were bulked and a composite sample was taken for analysis. The soil samples were taken from 0 to 20 cm depth in a y-shaped manner. These were bulked and a composite sample was taken for analysis. The sam- ple was air dried, sieved with a 2 mm mesh and analysed for both physical and chemical properties at the Soil Research Institute of Ghana in Kumasi. The chemical properties analysed were: organic matter content (Walkely Black Procedure), total N (Kjeldahl method), plant available P (Bray-1 method), exchangeable cations (K, Mg, Ca, Na) (1 M NH4OAc method) and micro-nutrients (Fe, Mn, Cu and Zn; ammonium acetate-EDTA extractable method). During the first round of the survey, soil samples were taken on every maize plot. Given that maize plots were not necessarily the same in every season, soil samples were only taken in the next season if farmers cultivated maize on a different plot, with the assumption that the soil status was unchanged for plots which were the same. 2.2.4. Demonstration experiments In 2016 and 2017 two demonstration experiments were carried out on four farmers’ fields in each of the selected villages, experiments and years (Appendix B). Two villages from each Nkoranza and Savelugu were selected in 2016, and in 2017 again two from Savelugu, but three villages from Nkoranza were selected. In Nkoranza, in 2016 the experiment was conducted in the minor season and in 2017 in the major season. The experiments in 2016 included 16 farmers and those in 2017 included 20 farmers (Appendix B); selection of the farmers was based on accessibility of the plot and willingness of the farmer to donate a plot. In experiment 1, we tested the effect of recommended and farmers’ planting density, at three different fertilizer application rates, on maize yield. The recommended planting density was 5.33 plants m⁻² and each of the participating farmers chose their own planting density. For each of the planting densities an N:P:K (23:10:5) fertilizer was applied at rates of 0, 250, 375 or 500 kg ha⁻¹. These treatment combinations resulted in a total of eight treatments per farm. A treatment plot measured 10 by 12 m. The hybrids Pannar (variety Pannar 53) and Proseed were used in 2016 and 2017, respectively, on all plots. In experiment 2, we compared the performance of three improved maize varieties with the local maize variety being cultivated by farmers. The maize varieties used were the farmers’ local variety, a drought tolerant maize (open pollinated variety), Obatanpa (the recommended open pollinated variety) and a hybrid (Pannar in 2016 and Proseed in 2017). In total there were four treatments, and a treatment plot measured 10 by 12 m. The recommended planting density of 5.33 plants m⁻² was used on all plots. In 2016, there was an outbreak of fall armyworm (Spodoptera frugiperda) in both Nkoranza and Savelugu with the incidence being more severe in Nkoranza than in Savelugu. The pest was controlled in Nkoranza using K-Optima EC * (Actetamiprid, 20 g l⁻¹) and Lambda cyhalothrin (16 g l⁻¹), a systemic insecticide and in Savelugu with Sunypryros 48 EC (Chlorpyrifos ethyl, 480 g l⁻¹). Two different chem- icals were used based on their availability. In experiment 1 in both 2016 in Nkoranza and 2017 in Savelugu, yield data from only three farms were obtained, because of the outbreak completely destroyed the maize crop in one of the fields. For both demonstration experiments maize yields were determined in the same way as during the household survey (Section 2.2.2). Farmers’ field days were held in each of the villages where the ex- periments were running at three different periods during crop growth: first fertilizer application, tasselling, and harvest. During the field days in 2016 there were on average 57 participants per field day, resulting in a total attendance of 680. In 2017, there were on average 47 partici- pants per field day, resulting in a total attendance of 713. During the field day at harvest, group discussions were held to rank the different treatments based on farmers’ preferences, and a final ranking was ob- tained based on a general consensus among the group. 2.3. Yield gap concepts and determination Since maize production by smallholder farmers in Ghana is mainly under rain fed conditions, we took the water-limited potential yield (Yw) as a benchmark. The yield gap (Yg) in this study was thus defined as the difference between Yw and the farmers’ average actual yield (Ya) (Van Ittersum et al., 2013). We refer to the relative yield gap (%) as equal to [1-Yf/Yw] * 100. Next, we defined the highest farmer yield (Yhf), which is the average yield above the 90th percentile (Silva et al., 2017). Farmers’ average actual yield (Yf) and Yw were based on the measured maize yields from the household survey (section 2.2.2). To estimate Yhf for Nkoranza and Savelugu for the 2015 and 2016 seasons we used the crop growth simulation model Hybrid-Maize (Yang et al., 2004 2006), which has been successful in simulating maize yields under various environmental conditions (Grassini et al., 2015; Meng et al., 2013), including Ghana (Van Ittersum et al., 2016). Details on model calibration and testing can be found in Grassini et al. (2015); Meng et al. (2013); Van Ittersum et al. (2016). The model simulates maize development and growth using a daily time-step, based on temperature driven development, temperature-sensitive maintenance respiration, vertical canopy integration of photosynthesis, and organ specific growth respiration. Daily weather data for 2015 and 2016 were obtained from the Savelugu weather station and, in the case of Nkoranza, from the Sunyani weather station. We used the same protocol for determination of the simulated sowing date and the planting density as that published in the Global Yield Gap Atlas (Grassini et al., 2015; GYGA, 2018; van Bussel et al., 2015). For sowing, this means that it was done when cumulative rainfall was > 20 mm within seven consecutive days in the specified sowing window, as defined by the local agronomist from the Global Yield Gap Atlas (Dobor et al., 2016; Wolf et al., 2015). Planting density was obtained from the actual average water deficit in the region and the relation between seasonal water deficit and planting density (Grassini et al., 2009). A generic maize variety was used, with growing degree days specific for the area. 2.4. Statistical analysis Quality control of the data was done in consultation with the persons carrying out the household survey. Suspicious data or outliers were verified at households involved and rectified if needed. If deviations could not be traced back, they were considered an outlier and removed when the value was outside the range of the mean +/- 3 times the standard deviation (McClelland, 2000). Different methods were used to study variance in yield, and crop management, soil and household variables. First, to test for significant differences between seasons and municipalities in crop management, soil, and household factors, Least Significant Difference (LSD) tests were performed using the agricolae package in R. Correlation analysis was performed on the yield data to test for relationship per plot and per farm (based on average yield) between the different seasons. Second, to visualise patterns in the data and to explain variance in yield and crop management and soil factors, a Principle Component Analysis (PCA) was performed using the Ade4 package in R. Five PCAs were performed: Nkoranza 2015 (minor season), Nkoranza 2016 (major season), Nkoranza 2016 (minor season), Savelugu 2015 and Savelugu 2016. Third, to test which factors significantly affected maize yield, multiple linear regression (MLR) was performed using the stats package in R. The MLR models had yield as the response variable and either the crop management, soil, or household factors as predictor variables. As with the PCAs, the MLR analyses were performed for each season and municipality combination and, variables with a large number of missing values were excluded from the analyses. In addition, a model was tested including both nutrient management and soil factors together. Including all factors and interaction was not feasible, because of limited degrees of freedom. Factors which caused collinearity were not included in the MLR model (selection was based on Variance Inflation Factor, using vifstep from the usdm package in R). Both PCA and MLR analyses were performed for each season and municipality combination separately, as the factors which affect maize yield were expected to differ for each of the seasons and municipalities. We also performed pooled analyses using multi-level models, in which both season and municipality were included as random factors. These models did not provide additional insights and results are therefore only presented in Appendix I and not discussed in the paper. Finally, to test for significant differences between pairs of treatments in the demonstration experiments a LSD test was performed. Fig. 3. Actual maize yields of plots for a) 2015 minor season in Nkoranza; b) 2016 major season in Nkoranza; c) 2016 minor season in Nkoranza; d) 2015 main season in Savelugu and; e) 2016 main season in Savelugu. The red continuous line is the average farmers’ yield (Y_a), the blue dashed line is the highest farmers’ yield (Y_{hf}) as defined by the average yield above the 90 th percentile, and the green dashed line is the simulated water-limited potential yield (Y_w). The arrows indicate the yield gaps (Y_g). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article). 3. Results 3.1. Farming system characteristics In Nkoranza, the households were characterised by their small family size, numbers of livestock and total farm area. This contrasts to Savelugu, where households had significantly more members, owned greater numbers of livestock and had larger total farm areas (Appendix C). In Nkoranza, rental of land for maize cultivation was fairly common, while this was not the case in Savelugu (Appendix D). Both municipalities also had similar characteristics: the use of inputs (fertilizer, manure, seeds, and herbicides) was comparatively low (Appendices C, D); next to herbicide no other agrochemicals were used; and the majority of the farmers used their own seeds saved from previous harvests and only a minority used certified improved seeds. Soil texture of all maize plots in Nkoranza and Savelugu was sandy or sandy loam. The soils in Nkoranza were generally more fertile with more available soil P, and higher percentages of N and organic matter compared to Savelugu (Appendix C). 3.2. Maize yields and maize yield gaps The simulated $Y_w$ were generally high, reaching 16.2 Mg ha$^{-1}$ in the 2016 major season in Nkoranza (Fig. 3b) and 14.1 Mg ha$^{-1}$ in 2015 in Savelugu (Fig. 3d). A comparison with a previous, long-term modelling study from the same regions confirmed that these values fall at the top of the range of attainable yields (GYGA, 2018). In both municipalities, these high values are largely explained by the high amount of well-distributed rainfall during the season. In the 2016 major season in Nkoranza the total precipitation was 538 mm while estimated reference evapotranspiration was 663 mm. In Savelugu, in both 2015 and 2016, total precipitation (608 mm and 585 mm, respectively) slightly exceeded evapotranspiration. The yield gap ($Y_g$) was large in all season and municipality combinations, except for the 2016 minor season in Nkoranza (Fig. 3). Here the relative yield gap was 68%, while for the other season municipality combinations it ranged from 81% to 87%. The low relative yield gap in the 2016 minor season in Nkoranza (Fig. 3e) was the result of a lower $Y_a$ due to water limitation. The water limitation ($\left(1 - \frac{Y_w}{Y_p}\right) \times 100$) was 60% for the 2016 minor season in Nkoranza, while it was less than 4% in the other season and municipality combinations presented here. For each season municipality combination, the simulated and the actual lengths of the growing seasons were similar. However, in Savelugu the simulated sowing dates were substantially earlier than the farmers actual sowing dates (day of year 152 versus 199 in 2015; day of year 155 versus 182 in 2016). This difference in sowing dates contributed to the large difference between $Y_w$ and $Y_a$. Overall, $Y_a$ was similar between the two municipalities (Fig. 3, Appendix C). Within Nkoranza, $Y_a$ was significantly higher in the 2016 major season compared to the minor seasons in 2015 and 2016 ($P < 0.01$). In Savelugu, $Y_a$ in 2016 was significantly higher than that in 2015 ($P < 0.01$). For both municipalities, there was not a significant relationship between yields from different seasons in the same plots (Fig. 4), and also not between the yield from different seasons when averaged per household (Appendix E). These unexpected results show that farmers obtaining high yields in one season did not necessarily obtain high yields in other seasons. 3.3. Principle component analysis Maize yield did not make substantial contributions to any of the PCs. Whereas, relations between yield and other variables were detected (Fig. 5, Appendix F, G), there was no consistency across seasons and sites. In the 2015 minor season in Nkoranza, yield was positively correlated with the amount of organic matter in the soil but negatively correlated with nutrient inputs (Fig. 5a). In the 2016 major season in Nkoranza, yield was negatively correlated with cation exchange capacity (Fig. 5b) and in the 2016 minor season, negatively correlated with the amount of organic matter in the soil (Fig. 5c). In 2015 in Savelugu, yield was positively correlated with nutrient inputs and negatively correlated with the percentage of clay in the soil (Fig. 5d), while in 2016 there was a positive correlation between yield and the percentage of clay in the soil (Fig. 5e). 3.4. Factors affecting maize yield Results from the MLR analysis were not consistent across seasons and municipalities (Table 1 and Appendix H). This is not surprising, because there was no correlation between yields from different seasons on individual fields or farms (Fig. 4, Appendix E). The MLR models with the most explanatory power in general were those based on the combination of nutrient management and soil factors, where the $R^2$ values ranged from 0.45 to 0.84 (Table 1). Individual factors that were statistically significant within the models predominantly related to soil variables and these varied between each model. In general, there was not a strong and positive relationship between N input and yield, except in 2015 in Savelugu (Fig. 6). Likewise, the other crop management variables included in the MLR analysis did not help to explain the variation in yield. Plant density at harvest had a significant effect on yield in three models. With respect to the household factors, the only significant, and consistent result from the MLR was that in Savelugu, for both seasons, there was a positive effect of livestock herd size (TLU) on yields. 3.5. Demonstration experiments Demonstration experiment 1, to test the effect of planting density at different fertilizer rates, showed fertilizer application resulted in higher maize yields compared to the treatment without fertilizer (Fig. 7; $P < 0.01$). This was not the case for the 2016 minor season in Nkoranza, where no significant differences were found between any of the treatments (Fig. 7a), which was probably due to the severe yield reduction across all plots due to the fall armyworm outbreak. Across all sites, there was no significant difference in yield when comparing application rates of 500 kg ha$^{-1}$ and 375 kg ha$^{-1}$ ($P = 0.65$). During the group discussions of the field days the farmers indicated that 375 kg ha$^{-1}$, i.e. equivalent to 86.25 kg N ha$^{-1}$, was their preferred fertilizer application rate (Table 2), which is much higher than the farmers reported average application rate of 27 kg N ha$^{-1}$ (Appendix C). No clear effect of planting density on yield was found in all municipality and season combinations (Fig. 7). Nevertheless, farmers indicated that they preferred the recommended planting density in Nkoranza in both 2016 and 2017 and in Savelugu in 2016 (Table 2). This preference led to farmers’ planting at higher densities in the 2017 round of the experiment, thus potentially impacting the comparison of results for that year. Looking at all factors together, farmers mentioned they preferred the combination of 375 kg ha$^{-1}$ of fertilizer, together with the recommended planting density and the hybrid seed. Yield was high (up to 9 Mg ha$^{-1}$) in the 2017 major season in Nkoranza across all treatments compared with the other season municipality combinations and when compared to yield levels found in the survey. This is probably the result of the use of hybrid seeds in 2017. The hybrid was also used in 2017 in Savelugu, but here, most likely due to drought at the end of July and beginning of August, yield levels were similar to those in 2016. Demonstration experiment 2 showed some differences in yield due to the maize varieties planted (Fig. 8). In the minor season in 2016 in Nkoranza, there was no significant difference among the different varieties (Fig. 8a), while in Savelugu in 2016, the hybrid Pannar had a significantly higher yield than the farmers’ variety (Fig. 8b ($P = 0.04$). In 2017, in both Nkoranza and Savelugu, the hybrid Proseed resulted in significantly higher yields than the other three varieties in the experiment (Fig. 8) \((P < 0.01\) for both municipalities). Despite the high yield of Pannar in 2016 the farmers indicated during the group discussion at harvest that they preferred the drought tolerant maize because those seeds are less expensive and can be recycled (Table 2). Proseed was preferred in 2017 due to the high yields, but farmers indicated that the price of the seeds is not within their reach (Table 2). 4. Discussion The large yield gaps observed in this study in Nkoranza (i.e., 69% and 76% in the minor and major season) and Savelugu \((Y_g\) was 75%) municipalities show that there is substantial potential to increase maize yields in the study sites and, more broadly across the forest/savannah transitional and southern Guinea AEZs. This is consistent with what has been found for the whole of Ghana, for which the average yield gap is 80% (GYGA, 2018). However, despite the large potential to increase the maize yield in Nkoranza and Savelugu municipalities in Ghana, we did not find consistency in factors that have impact on maize yields and yield gaps when combining data sources and methods of analyses across sites, seasons and levels of analysis. In a review of yield gap analyses, Beza et al. (2017) showed that, across studies, explanations of the yield gap often differ which can be a result of the factors considered in each study. In discussing our results, we used the framework of van Ittersum and Rabbinge (1997), which groups potential causes of the yield gap into growth-defining, growth-limiting and growth-reducing factors. We also discuss the challenging aspects of the results and the methodological, practical, and policy implications of this study. 4.1. Growth-defining factors The demonstration experiment showed higher yields could be obtained when improved maize varieties are used (up to 9 Mg ha\(^{-1}\)), although this effect was not always observed (Fig. 8, Fig. 7b). Other studies confirm the potential of improved varieties compared to farmer-saved seeds (Asiedu et al., 2008), under favourable production environments, including good management (Adu et al., 2014). Nevertheless, all farmers from the survey used open pollinated varieties and saved their seeds for subsequent seasons. This is attributed to the lack of cash at planting to obtain seeds in combination with the prohibitive cost of hybrid seeds, as they explained during the group discussion. The demonstration experiments did not confirm that the recommended planting densities out-performed farmers’ planting densities in terms of maize yield. However, farmers perceived that increasing planting density did increase yield as they observed more plants per unit area (Table 2). Interestingly, those participating in the experiment changed their behavior and increased their planting density in the second year of experiment 1. From farmers’ fields, we do not have precise data on planting densities, which hinders clear conclusions. 4.2. Growth-limiting factors According to model simulations, water supply was only substantially limiting crop growth during the 2016 minor season in Nkoranza. The favourable conditions are reflected in the high simulated values for \(Y_w\) (GYGA, 2018). It is possible that these simulations underestimated water limitations on individual farmers’ fields as they were based on precipitation recorded at a single weather station for each municipality. Analysis of the farm survey data did not clearly show that the use of fertilizer increased maize yields for any of the municipality and season. combinations, while in the demonstration experiments fertilizer did increase yields (Fig. 7 versus Fig. 8). A possible explanation for the differences in yield response to fertilizer between the household survey and the demonstration experiment could be the low fertilizer application rates applied on farmers’ fields (i.e., on average 27 kg N ha\(^{-1}\); note this is substantially more than the 5 kg N ha\(^{-1}\) reported as average N input in Ghana by the FAO (FAO, 2018)) compared to the fertilization rates used in the demonstration experiments (i.e., ranging between 57.5 and 115 kg N ha\(^{-1}\)). It is thus not a great surprise to see such low rates having minor effects on yields. Moreover, several management and environmental factors that interact with fertilizer input (Getnet et al., 2016) were controlled for in the demonstration experiment, namely sowing density, time of fertilizer application, crop variety and pest control (Tittonell et al., 2008). Thus, the value of combining these results lies in the implication that at least a minimum rate of fertilizer should be supplied to positively impact yields. 4.3. Growth-reducing factors Our study lacked sufficient data to analyse the impact of pest Fig. 5. Plots showing the relation between, and contribution of, different variables to the first two principle components (PC1 and PC2) for a) 2015 minor season in Nkoranza; b) 2016 major season in Nkoranza; c) 2016 minor season in Nkoranza; d) 2015 main season in Savelugu and; e) 2016 main season in Savelugu. Variables with latent vectors less than 0.5 (with the exception of yield) are not labelled (a variable with a latent vector with a value close to one indicates that the variable makes a large contribution to the component axis). The average contribution to PC1 and 2 (%) = [(C1 * Eig1) + (C2 * Eig2)] / (Eig1 + Eig2), where C1 and C2 are the latent vectors and Eig1 and Eig2 are the eigenvalues for PC1 and PC2, respectively. The correlation matrix of latent vectors is provided in Appendix G. The percentage of variance explained by each principle component is presented on the axis labels in brackets (see also Appendix F). incidences and diseases. Fall armyworm reduced yields in both demonstration experiments in 2016 and 2017, and probably also the surveyed farmers' yields from the 2016 season, but no reporting was done on actual pest infestations. The farm survey data indicated that no farmers applied pesticides during the 2016 seasons. Day et al. (2017) indicate that maize yields in Ghana were reduced by 45% in 2017 due to fall armyworm attack. Other studies have indicated that agrochemicals can be positive determinant of maize yield (Addai and Owusu, 2014; Awunyo-Vitor et al., 2016; Bempomaa et al., 2014; Oppong et al., 2014) and integrated pest management should be part of sustainable intensification of maize production in our study sites as well. 4.4. Challenging results A first challenge of our results is that a relatively short term study like this one is not well equipped to capture factors that vary between season, e.g. management decisions, pest and disease outbreaks and weather patterns. This calls for caution in the interpretation of results, and for more long-term studies to better understand relationships and dynamics. In this study, we observed little relation between yield obtained by individual farmers between seasons. This is likely due to the temporal variability in climate, management, and household factors, the impact of which becomes larger with sub-optimal management conditions (Fermont et al., 2009). Another study in Uganda reported that farmers make significant changes to their crop management from season to season (Ronner et al., 2018). Even in long-term studies, correlations between yields of farmers in different years are relatively low (Silva et al., 2018). Second, all farmers in the study sites achieved yields far below $Y_w$ with relatively small differences between the farms. The uniform and low yields can be explained by the incidence of fall armyworm, but also by the low-input nature of the systems (see relatively large difference between $Y_w$ and $Y_{hf}$ values in Fig. 3) and low soil quality in general (e.g. very low soil Zn). Finally, errors in data collection (e.g. arising from relying on farmer recall) complicate the identification of consistent relationships (Kassie et al., 2013). Compared to the separate models per location and season, no additional insights were obtained by pooling data in the multi-level regression model (Appendix I). 4.5. Methodological, practical and policy implications The practical aim of this study was to identify options to mitigate yield gaps. However, disentangling spatial and temporal factors in biophysical, social and economic domains that interact and impact crop yields proved to be difficult. Nevertheless, our integrated approach combining different data sources and methods helped to reveal complexity that must not be ignored, but instead be incorporated in yield gap analysis. Employing different methods provided both confounding and complementary results. Therefore, we highlight the danger of drawing over-simplified conclusions based on a single method that in turn may lead to potentially unjustified crop management recommendations. Smallholder systems are complex and heterogeneous and blanket recommendations to increase yields are often irrelevant, infeasible and risky (Berre et al., 2017; Giller et al., 2011). Our results confirm that, in terms of offering recommendations to mitigate yield gaps, a “basket of options” that includes technologies and practices that farmers can choose, try and adapt is more appropriate (Ronner et al., 2018). In this case, the farm-level “basket” may include a selection of adapted varieties, fertilizer rates and pest control methods, i.e. options that all contribute to good agronomy. Further research that investigates how such a “basket” is used over multiple seasons would be extremely | Table 1 | Significant factors from the multiple linear regression models of crop management, soil and household factors which affect maize grain yields in Nkoranza and Savelugu for the different seasons. Estimates of each of the factors are given and the significance stated: *** $P < 0.001$, ** $P < 0.01$, * $P < 0.05$, + $P < 0.1$, R² of the models and the number of observations (n) are provided below the response variables. An x in the table indicates that the variable was excluded from the analysis due to a large number of missing values. The full regression model can be found in Appendix H. | | --- | --- | --- | --- | --- | --- | --- | | **Crop management** | **Minor season - 2015** | **Major season - 2016** | **Minor season - 2016** | **Nkoranza** | **Savelugu** | | Plant density (harvest) | –0.14 | 0.83*** | 0.77** | 0.07 | 0.54* | | N input | –0.08* | 0.00 | –0.04 | 0.08** | 0.02 | | Model R² | 0.30 | 0.36 | 0.37 | 0.40 | 0.38 | | n | 36 | 46 | 34 | 42 | 40 | **Soil** | Mn | –0.39* | –0.26+ | –0.08 | x | x | | Percentage silt | 0.96 | 1.30* | –0.95 | 2.06 | –0.66 | | CEC K x exchange acidity | 0.65 | 1.20 | –0.36 | 0.50 | 2.54* | | Soil P x Cu | –1.36 | –0.29 | –1.17+ | 2.44 | 0.90 | | CEC Mg | 9.53 | 0.11 | 1.96 | –6.15 | 0.04 | | CEC Ca x CEC Mg | –6.28 | –0.01 | –1.40 | 3.29 | 0.45 | | Model R² | 0.58 | 0.68 | 0.49 | 0.25 | 0.57 | | n | 51 | 48 | 45 | 47 | 43 | **Nutrient management and soil** | N input | –0.04 | 0.01 | –0.02 | 0.07* | –0.01 | | Dummy variable no P input | –0.02 | 0.05 | –0.57* | 0.11 | –0.35 | | Soil P x Cu | –3.55+ | 0.50 | –0.94+ | 2.21 | 1.70 | | CEC Mg | 19.43* | 0.55 | 1.54 | –7.75 | 0.55 | | CEC Mg x CEC Ca | –12.17* | –0.43 | –1.38 | 5.01 | 0.18 | | Mn | –0.16 | –0.31+ | –0.40 | x | x | | Percentage silt | 0.92 | 1.53* | 0.60 | 2.34 | –0.73+ | | Model R² | 0.84 | 0.66 | 0.56 | 0.45 | 0.65 | | n | 40 | 47 | 44 | 46 | 43 | **Household** | TLU | 0.00 | 0.01 | –0.04 | 0.17** | 0.14* | | Family labour available | –0.10 | 0.12 | 0.61 | –1.66* | –1.38 | | People in the household | –0.22 | –0.40+ | 0.05 | –2.97* | –0.54 | | Family labour available x people in the household | 0.35 | 0.26 | –0.28 | 0.74* | 0.55 | | Model R² | 0.53 | 0.57 | 0.37 | 0.66 | 0.64 | | n | 35 | 33 | 34 | 37 | 36 | valuable. Innovative data collection methods including crowdsourcing and sensor technology (Beza et al., 2017), and data science (e.g., Janssen et al., 2017) can contribute to integrated assessments to explain yield gaps. We can nevertheless conclude that given the importance of socioeconomic constraints faced by farmers, policies can contribute to closure of the maize yield gap in Ghana by improving the availability and access of farmers to improved seeds. Next, affordability of fertilizers is likely to contribute to yield improvements. Finally, we ![Fig. 6. Yield versus N input for Nkoranza and Savelugu for the 2015 and 2016 seasons. Dashed lines represent the recommended N input.](image) ![Fig. 7. Average maize yield with standard error from demonstration experiment 1 for farmers’ chosen planting densities (F, dark colored bars) and recommended planting density (5.33 plants m$^{-2}$) (R, light colored bars) at fertilizer application rates (N:P:K 23:10:5) of 0 (grey bars), 250 (yellow bars), 375 (green bars) or 500 (blue bars) kg ha$^{-1}$ for a) 2016 minor season in Nkoranza; b) 2017 major season in Nkoranza; c) 2016 in Savelugu and; d) 2017 in Savelugu. Bars labelled with different letters within each graph indicate significant differences in yield, $P < 0.05$ based on the LSD analysis. The red continuous line is the average actual yield ($Y_a$) as measured during the household survey, the blue dot dashed line is the highest farmers yield ($Y_{hf}$) as measured during the household survey, and the green dashed line is the simulated water-limited potential yield ($Y_{w}$) (see also Fig. 4). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).](image) recommend improving integrated pest management by farmer capacity building and improved information access through extension services. 5. Conclusion We conclude that there is great potential to increase maize yields within low-input smallholder farming systems in Ghana. However, identifying recommendations to achieve such yield improvements is far less straightforward because farmers’ yields are determined by interacting, and often strongly varying, household, soil and management factors. Our study showed that it is often not possible to make sense of these factors on the basis of a single methodological approach. Instead, results obtained through individual methods should be interpreted in light of complementary methods that account for the multiple yield-determining factors acting at different spatial and temporal levels. The combination of household survey, crop growth simulation modelling, and demonstration experiments with farmers’ feedback used in this study adds value to yield gap analysis of maize in Ghana. Demonstration experiments showed that improved varieties and increased fertilizer rates can lead to yields much closer to water-limited yields, whereas farmers’ yields differed among plots and seasons, and explaining factors differed per season and site. Nevertheless, the approach can be improved upon with additional data sources and methods that better disentangle variation in space and time. Table 2 <table> <thead> <tr> <th>Variety</th> <th>2016</th> <th>2017</th> <th>2016</th> <th>2017</th> <th>Comments</th> </tr> </thead> <tbody> <tr> <td>Nkoranza Savelugu</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>Fertilizer rate (N:P:K, 23:10:5) (kg ha⁻¹)</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>0</td> <td>4</td> <td>4</td> <td>4</td> <td>4</td> <td></td> </tr> <tr> <td>250</td> <td>2</td> <td>2</td> <td>2</td> <td>3</td> <td></td> </tr> <tr> <td>375</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td> <td></td> </tr> <tr> <td>500</td> <td>3</td> <td>3</td> <td>3</td> <td>2</td> <td></td> </tr> <tr> <td>In 2016 and 2017 375 kg ha⁻¹ of N:P:K fertilizer preferred, because: yield and growth performance was high and was not much different from that of 500 kg ha⁻¹, but was better compared to 0 and 250 kg ha⁻¹; cob sizes were uniform and their weights were close to that of 500 kg ha⁻¹; 375 kg ha⁻¹ fertilizer is similar to what is recommended by research and extension; more cost effective to use 375 kg ha⁻¹ than 500 kg ha⁻¹; financial constraints to purchase 500 kg ha⁻¹ of fertilizer; in 2017 resulted in delayed drying of cobs thus delaying harvesting for this treatment.</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>Planting density</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>Farmers</td> <td>2</td> <td>2</td> <td>2</td> <td>1</td> <td></td> </tr> <tr> <td>Recommended</td> <td>1</td> <td>1</td> <td>1</td> <td>2</td> <td></td> </tr> <tr> <td>Recommended planting density preferred in Nkoranza 2016, and 2017 and Savelugu 2016 because: higher yields could be achieved with this higher planting density; in Nkoranza farmers noted that it gives more plants per unit area, and they are already used to row planting so increasing the rate may not be too difficult. Farmers planting density preferred in Savelugu 2017 because: recommended planting density involves row planting, which requires more labour due to obstruction by trees in the field.</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>Variety</td> <td>1</td> <td>3</td> <td>1</td> <td>2</td> <td></td> </tr> <tr> <td>Drought Tolerant Maize (DTM)</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>Farmer variety</td> <td>4</td> <td>2</td> <td>4</td> <td>4</td> <td></td> </tr> <tr> <td>Obatanpa</td> <td>3</td> <td>4</td> <td>3</td> <td>3</td> <td></td> </tr> <tr> <td>Pannar</td> <td>2</td> <td>–</td> <td>2</td> <td>–</td> <td></td> </tr> <tr> <td>Proseed</td> <td>–</td> <td>1</td> <td>–</td> <td>1</td> <td></td> </tr> <tr> <td>In 2016 DTM preferred because: uniform and with filled cobs; yield was high and consistent across all fields; recycling of seeds is possible unlike Pannar seeds; Pannar seeds are expensive. In 2017 Proseed preferred even though the price is not within reach of farmers because: high and consistent yield across most fields; good and uniform germination; well-filled cobs; large grain size.</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </tbody> </table> Fig. 8. Average maize yield with standard error for different varieties used in demonstration experiment 2 (note that in 2016 Pannar is used as a hybrid and in 2017 Proseed is used) in a) Nkoranza and b) Savelugu. The dark grey bars show results for 2016 and the light grey bars for 2017. Different letters indicate significant differences in yield, P < 0.05, between the different treatments within each season and municipality combination.
Other Books by the Author Fiction The Jewels of Aptor (1962) The Fall of the Towers: Out of the Dead City (formerly Captives of the Flame, 1963) The Towers of Toron (1964) City of a Thousand Suns (1965) The Ballad of Beta-2 (1965) Empire Star (1966) Babel-17 (1963) The Einstein Intersection (1967) Nova (1968) Driftglass (1969) Equinox (formerly The Tides of Lust, 1973) Dhalgren (1975) Trouble on Triton (formerly Triton, 1976) Return to Nevërÿon: Tales of Nevërÿon (1979) Neveryôna (1982) Flight from Nevërÿon (1985) Return to Nevërÿon (formerly The Bridge of Lost Desire, 1987) Distant Stars (1981) Stars in My Pockets Like Grains of Sand (1984) Driftglass/Starshards (collected stories: 1993) They Fly at Ciron (1993) The Mad Man (1994) Hogg (1995) Atlantis: Three Tales (1995) Graphic Novels Empire Star (1982) Bread & Wine (1999) Nonfiction The Jewel-Hinged Jaw (1977) The American Shore (1978) Heavenly Breakfast (1979) Starboard Wine (1984) The Motion of Light in Water (1988) Wagner/Artaud (1988) The Straits of Messina (1990) Silent Interviews (1994) Louder Views (1996) Times Square Red, Times Square Blue (1999) Shorter Views Queer Thoughts & The Politics of the Paraliterary Samuel R. Delany Wesleyan University Press Published by University Press of New England • Hanover and London 1999. The Rhetoric of Sex / The Discourse of Desire 1. Apples and Pears. In the two dozen years between 1488 and 1512, Leonardo da Vinci produced a series of fascinating anatomical drawings that strike the modern viewer as highly realistic and rich with the texture and look of the bodies whose dissections he observed or, no doubt, took part in, as he drew from life—or more accurately, from death—his schemas of the blood vessels, the workings of the heart, the bladder and urinary system, the womb and the fetus inside it. These drawings are clearly and carefully observed, detailed, and rich in layerings and representations of tissue texture—and practically useless to a modern anatomist. For as we look closer, we find there are no atriums or auricles in his depiction of the human heart; rather, he shows a two-chambered affair with only ventricles; and while here and there we can recognize the aorta and the esophagus, as well as the larger organs, the circulatory system and the alimentary system are depicted in gross form; there are no articulations shown between the stomach and the intestines (mostly absent from his drawings, though not his writings). And in an early anatomic depiction of heterosexual copulation, a “wholly fictitious piece of plumbing” (to use the commentator’s term from the 1989 catalogue of the Haywood Gallery da Vinci exhibition in London) runs from the man’s penis, bypassing the testicles, to the small of the back, where many during the Italian Renaissance believed “the seed of life” was manufactured. Indeed, hardly any vessel shown in any of Leonardo’s anatomic interiors connects up to what, today, we are fairly certain that it does. And what are we to make of Leonardo’s depiction of the womb? For the modern anatomist, the uterus is traditionally described as pear-shaped, small end down, and connected by means of the cervix to the vaginal cavity. The pear-shaped bulge at the upper end is largely a product of the entrance into the uterus of the fallopian tubes, which, left and right, lead back from the outer ends of the ovaries to conduct the egg to the wall of the uterine cavity. Leonardo’s womb, however, whether it is engorged with a “four month old fetus” as in the pen and ink drawing with wash over traces of black and red chalk from 1510-12, “The Fetus in the Womb,” or whether it is without child, as it is in the 1507 drawing of pen and ink and wash on waxed paper, “The Principal Organs and Vascular and Urino-Genital System of a Woman,” is as round as an apple. In “The Fetus in the Womb,” while an ovary is indeed shown, only the vascular connection about the base is drawn; there is no connection at all from the business end of the ovaries to the womb proper. The fallopian tubes and all the muscular protruberances of the upper end are omitted as tissue irrelevancies to the womb’s presumed perfect, Renaissance sphericity. Nor is this surprising. The assumption of the times was that the material relation obtaining between a man and his offspring was that between seed and plant. The relation between a woman and her offspring, however, was that of contiguity, sympathy, resemblance through imposed distortion—of environment to plant. Certainly, people had noticed that a child was as likely to resemble its mother or people in its mother’s family as it was to resemble its father or people in its father’s family. But the assumption was that paternal resemblances and maternal resemblances were of two different orders. You resembled your father because you were grown from his seed. You resembled your mother, however, because you spent so much time in her womb that you picked up her traits—because her food had been your food, her pains your pains, her sorrows your sorrows, her soul your soul. In one of the notes on the drawing “The Fetus in the Womb,” in da Vinci’s famous mirror writing, we find Leonardo’s clear expression of the maternal sympathy between the body of the mother and the body of the child: In the case of the child the heart does not beat and ... breathing is not necessary to it because it receives life and is nourished from the life and food of the mother. And this food nourishes such creatures in just the same way as it does the other parts of the mother, namely the hands and other members. And a single soul governs these two bodies, and the desires and fears and their passions are common to this creature as to all the other animated members. And from this it proceeds that a thing desired by the mother is often found engraved upon those parts of the child which the mother keeps in herself at the time of such desire and sudden fear kills both mother and child. We conclude therefore that a single soul governs the two bodies and nourishes the two. (McCurdy 173) The Rhetoric of Sex/The Discourse of Desire On the same drawing, fascinating enough, there is talk of a female seed: The black races of Ethiopia are not the product of the sun; for if black gets black with child in Scythia, the offspring is black; but if a black gets a white woman with child the offspring is gray. And this shows that the seed of the mother has power in the embryo equally with that of the father. (McCurdy 173) But from what one knows of the range of Renaissance writings, the maternal seed, for all its presumed equality with the male, was a highly metaphorical one—just as the male “seed” was to become mere metaphor upon discovery of sperm and egg reproduction. But in the common course of things, it was generally not given much credence as long as one was within the country, the family, the race. Leonardo died in France during the late spring of 1519. Four years later in 1523 at the tiny town of Modena, Italy, Gabriele Fallopio was born. Soon Fallopio became canon of the Modena cathedral. He studied medicine at Ferrara, then embarked on a world tour, during which he spent a while working with the great Belgian anatomist, Andrea Vesalius. He returned to Ferrara, where he now taught anatomy, having long since switched his name to the Latin form that befit a Renaissance scholar and under which he is more widely known today: Fallopius. Thence he removed to Pisa, and from Pisa, on the installment of the new grand duke of Tuscany, Cosimo I, to Padua, where, besides the chairs of anatomy, surgery, and botany, he was also created superintendent of the new botanical garden. It was Fallopius who discovered the opening of the ovarian tube of the human female into the abdominal cavity. As well, he named both the vagina (after the Latin for scabbard) and the placenta (after the Greek for pancake). He died in Padua in 1562, a year after publishing (in Venice) his single treatise. The fallopian tubes (which retained a capital Fesuitori) into the 1830s but lost it by the 1870s) have borne his name ever since. With Fallopius’s anatomy, the spherical womb of Leonardo gave way to the pear-shaped womb we are familiar with from the modern anatomical vision. But what I have tried to dramatize in this little narrative is the force shaping the very sight itself of a visionary as great and as revered as any in our culture. Leonardo da Vinci. It is the till-now-in our-tale unnamed structuring and structuring force that can go by no better name than “discourse.” For what has metamorphosed between Leonardo and Fallopius is the discourse of the body itself—medical discourse, anatomical discourse—and that force seems strong enough to contour what is apparent to the eye of some of the greatest 2. Interlogue One. I pause here to say that, thanks to my title, I feel somewhat like the man who shouts, "Sex," then continues on to say, "Now that I have your attention . . ." For we have come to the real, i.e., the political, topics of my essay, which are rhetoric and discourse. Sex and desire—while they may now and again provide some of the more dramatic narratives through which we shall endeavor to show how discourse can manifest and problematize itself through rhetoric—will in my essay remain largely occasions for the exploration of rhetoric and discourse themselves. And though we will return to sex and desire again and again, and even try to plumb them for the secrets of the misfiring of so many relations called "sexual" between men and women. men and men, women and women, we shall stray from them again and again—to areas as diverse as children's picture books and children's games around a fountain in Central Park, to tales told over a calabash of beer in the rainy season of the West African Tiv, to very similar-sounding criticisms of writers as different as Ursula Le Guin and Toni Morrison, to dimly perceived objects in a house in Amherst at the edge of dawn, to the lack of operationalism in AIDS research. But now we ask: What is this "discourse" that has so long protruded its rhetorical stumbling block into the jargon-heavy realms of literary theory, either since the Middle Ages or World War II, depending on whose account you read? Well, here's a tale of a tale. 3. Pictures and Books. I have an eighteen-year-old daughter. And fifteen years ago, when she was three and just beginning to read (and, even more, enjoying being read to), like so many parents of those years I noticed that there were precious few children's picture books with female protagonists. Somehow, with the exception of Frances the Hedgehog, the illustrated bestiary in these books was overwhelmingly male. This struck me as ridiculous as well as unfair—and even, perhaps, dangerous. Who knew what happened to children whose only identificatory objects resided outside their race, their class, their sex, their gender—not to say their kind? Indeed, having proved itself powerful enough to stabilize the process by which the nation's schools had been desegregated, an entire discourse from the fifties was already in place with its unpleasant suggestions precisely about the answers to that seemingly rhetorical question. What was a parent to do with such books when little girl animals were simply not extant? One book that fell into my hands, back then, was a charming and well-drawn affair, about a little bear called Corduroy. What's more, Corduroy wore a pair of denim Oshkosh overalls—as did my three-year-old on most of her days at playschool. Certainly, there was a point of correspondence. Why couldn't I simply up and change Corduroy's sex in the telling? With white-out and felt-tip pen, I went so far as to remove the he's and change the pronouns to she's—in case Iva's reading had actually progressed further than I suspected. Then I sat down, with my daughter. I began the story—and at the first pronoun, Iva twisted around in my lap to declare: "But Daddy, it's a boy bear!" "I don't think so," I said. "The book says 'she' right there." "But it's not!" she insisted. I was sure of my argument. "How do you know it's a boy bear?" "Because he's got pants on!" Surely she had fallen into my trap. "But you're wearing pants," I explained. "In fact, you're wearing the same kind of Oshkosh overalls that Corduroy is wearing. And you're a little girl, aren't you?" "But Daddy," declared my three-year-old in a voice of utmost disdain at my failure to recognize the self-evident, "that's a book!" During the same three or four months' reading in which I was learning of the rhetorical failure of the discourse of children's picture books to provide an egalitarian array of multigendered protagonists, my daughter, of course, had been learning that discourse itself. And the fact was, she was right—I was wrong. Corduroy was a boy. No matter how unfair or how pernicious it was or might prove, the discourse of children's books made him a boy. And that discourse was so sedimented that a single instance of rhetorical variation, in 1977, registered not as a new and welcomed variant but, rather, as a mistake self-evident to a three-year-old. "Well," I said, "let's make Corduroy a 'she.' We'll pretend she's a girl, just like you." Iva had also learned the discourse of "let's pretend"—surely from the same books that had taught her pants (in books) meant male. She settled back in my lap and seemed satisfied enough with the revised story. Today, in the shade of its shelf, Corduroy has dust on its upper edge. But days ago I phoned Iva in the city where she was getting ready to go off to college next year, and—in preparation for this essay—I asked her whether she had any memory of the incident. No, she didn't. "But once I was looking through some of my old picture books, and I remember finding *Cardano* and realizing someone had taken a pen and changed all the he's to she's. I remember wondering why they'd done it." 4. Interlogue Two. Perhaps here is the place to state some principles, then, of discourse. Discourses are plural and are learned, with language, where they function as a particular economic level in the linguistic array. They are not a set of criteria that are to be met or missed by a text. Rather, they lodge inclusively in the processes by which we make a text make sense—by which we register a text well-formed or ill-formed. They are revisable, often from within themselves. The maintenance of a discourse, like the revision of a discourse, always involves some violent rhetorical shift—though the final effects of that violence may well be in some wholly unexpected area of understanding that the discourse affects. And most discourses worth the name have complex methods—starting with simple forgetfulness—for regularly healing themselves across such rhetorical violations. And this is also the place to recall a comment by my fellow science-fiction writer, Ursula Le Guin: Only adults confuse fantasy and reality; children never do. From this anecdote of a parent, a child, and a picture book, it is not too great a leap to the suggestion that wherever the world appears (in Plato's phrase) "illuminated by the sun of the intelligible," the light that does the illuminating is discourse. But what our earlier tale of Fallopian and Leonardo reminds us is just how powerful a light that is. For it may make a pear look like an apple—or, indeed, an apple look like a pear. 5. Text and Text. Here are two texts that I think might have been much clarified by the notion of discourse: For here is a young woman, who signs herself J. R. Dunn,* writing a critique of a recent article by Ursula Le Guin in a letter to *Monad*, an informal critical journal devoted to science fiction: > In her opening pages, Le Guin stated that: "... in the European tradition the hero who does great deeds is a white man... human women were essentially secondary, taking part in the story only as mothers and wives of men, beloved by or the seducers of men, victims of or rescued by men. Women did not initiate action, except passively... the great deeds were men's deeds." I don't think I'm mistaken in taking this as the essay's key premise. That being so, it's unnecessary to go on any further: My argument with Le Guin lies right there. That passage represents the standard feminist historical model in action: that before the modern era women were victims at best, a mute inglorious mass marked by biology, allowed no contribution to any branch of human endeavor, the history of the female sex is a vast honeycomb of oppression, suffering and degradation. This interpretation has been institutionalized for two decades and it's late in the day to pick a fight over it. But I believe that it is in error, and those adhering to it are seriously contradicted by the record. Dunn then goes on to give a catalogue of great women of accomplishment in the West, from warrior queens such as Telesilla of Argos, Zenobia of Palmyra, and Boadicea of Great Britain, on to women cultural figures, such as Sappho, Anna Commena, Juliana of Norwich, Christine de Pisan, Vittoria Colonna, and Anne Bradstreet, punctuated with a list of the great tragic heroines from Greek drama. And toward her conclusion (I abridge), Dunn writes: I'm not suggesting that Le Guin doesn't know any of this. I'm sure she does. It just doesn't connect. I won't speculate on why except to note that ideology tends to restrict critical thinking. This happens to the best of us. It's happened to me... . I accept the proposition that feminism is divided into egalitarian and various radical branches. I strongly support the egalitarian position on grounds of logic and common sense. The other variants, "gender" or "radical" feminism, what have you, I can only reject, seeing the nature of the "facts" they're based on. I object to any contention that the two streams are in any way one and the same. I'll go on to say I can picture few greater social tragedies than egalitarian feminism collapsing in the wreckage of the weirder varieties. I hope it will not simply be a jejune exercise to point out that, in her pursuit of logic and common sense, Dunn has misread Le Guin and accomplished a truly astonishing rewrite of history—a misreading and a rewriting that can be aplied apart by the careful insertion of a notion of discourse that will, perhaps, yield us its analytical fruit. But before I do so, I want to offer another text, this time on racial matters, that seems ripe for the same sort of misreading that Le Guin's text has fallen victim to in Dunn. For some time now I have been thinking about... a certain set of assumptions conventionally accepted among literary historians and critics and circulated as "knowledge." This knowledge holds that traditional, canonical American literature is free of, uninformed, and unshaped by the four-hundred-year-old presence of, first, Africans and then African-Americans in the United States. It assumes that this presence—which shaped the body politic, the Constitution, and the entire history of the culture—has had no significant place or consequence in the origin and development of that culture's literature. . . . There seems to be a more or less tacit agreement among literary scholars that, because American literature has been clearly the white male view, genius, and power, those views, genius, and power are without relationship to and removed from the overwhelming presence of black people in the United States.5 It is all too easy to see, at some not-so-distant point, such a paragraph from Morrison taking its place within a critique of some fancied radical liberation movement much like Dunn's critique of "radical" feminism; and some young reader, straight from a perusal of the paperback shelves of his or her local college bookstore, bringing out the currently available paperback editions of Phillis Wheatley's Poems and the slave narratives from Olaudah Equiano and Frederick Douglass and Harriet E. Wilson's Our Nig and Martin Delany's Blakes and the stories of Charles W. Chesnutt and novels of Iola Harper and Zora Neale Hurston and Richard Wright and Chester Himes and William Demby, and citing the National Book Award to Ralph Ellison and McPherson's and Johnson's and even Morrison's own Pulitzer Prize, in order to declare: "How can you say that there's a conspiracy to keep centuries of black American writers from being considered a literary presence . . . ?" The safest place to begin to answer either Dunn's criticism of Le Guin or my hypothetical critic of Morrison is with the historical truism: Things as they are today are not necessarily the same as they were even ten or fifteen years ago, much less twenty-five or thirty, much less fifty or seventy-five years gone. We can only hope that point will hold the arguments stable long enough to look in more detail at both Le Guin's and Morrison's initial statements. For they share a number of rhetorical features. On the one hand, "white males" are the putative villains of both passages. (Are they heterosexual? But of course. We do not even have to ask—for there is a discourse already in place that makes that at least as inarguable as the sex of Corduroy in 1977.) On the other hand, the words "tradition" and "traditional" in both take a deceptively en passant role among the opening sentences of each. And it is within the notion of tradition that what we call discourse—traditionally—hides. Articulating it might have avoided some of these subsequent problems. Had Le Guin or Morrison been able to foreground it clearly, instead of leaving it implicit under the "traditions" both are citing and for which the "heterosexual white male" more than anything else stands as a marker, a name, an indicator of a dominant current in the ideology of the present century, their passages might be less subject to such accusations and misrepresentations. I'd like to think that if, instead of, "In the European tradition, the hero who does great deeds is a white man" Le Guin had written, "In traditional European discourse, the hero who does great deeds is a white man," Dunn's subsequent confusions might have been less inevitable. Or if Morrison had written, "This knowledge holds that in the traditional discourse of canonical, American literature, that literature is free of, uninformed, and unshaped by the four-hundred-year-old presence of, first, Africans and then African-Americans in the United States," then perhaps my hypothetical critic might have been less confused. Of course, discourse is a strong and meaningful concept for me. It represents an economic order of language that is apart from tradition itself as it is apart from doctrine and ideology; though it leans on aspects of all of them, as all of them lean on aspects of discourse. But I am aware that possibly what characterizes Dunn or my other hypothetical spoilt-sport critic, is that the concept of discourse may be what they themselves lack. For what discourse does above all things is to assign import. Discourse, remember, is what allows us to make sense of what we see, and hear, and experience. Yes, the Zenobias and the Christine de Pisans, the Wilsons and Chesnotts and Hurstons were there. But discourse is what tells us what is central and what is peripheral—that is, what is a mistake, an anomaly, an accident, a joke. It tells us what to pay attention to and what to ignore. It tells us what sort of attention to pay. It tells us what is anomalous and therefore nonserious. And till very recently "anomalous and nonserious" is how the accomplishments of women, whether in the arts or in the world, were judged. And the writings of blacks in this country were, until very recently, considered even more of an accident. The rewriting of history I've spoken of is simply that it would be hard to make a list of the works that have done more to change the discourse of gender so that, today, Dunn or I can walk into our local bookstores and buy a copy of Christine de Pisan's City of Ladies, that did not include Le Guin's works, such as The Left Hand of Darkness (1969) and The Dispossessed (1974). It would be hard to make a list of those works that had helped change the discourse of race so that we can now walk into the same bookstore and buy any of the paperback volumes in the Schomburg Library of nineteenth-century black women writers, that did not include Morrison's own novels Sula (1973) and Song of Solomon (1977). What it is necessary to remember, in order to make discourse a strong concept, is that it is the materialist side of reason and ratiocination, of understanding and history. It is all very well to explain that electric lights were simply not very common seventy or eighty years ago. Or that, even in my own early childhood in the 1940s, our perfectly comfortable country house, which we drove to every summer, was lit by kerosene lanterns. Or that, at the same time, the country house of my uncle, a fine and upstanding judge in the Brooklyn Domestic Relations Court, had no indoor toilet facilities but only an outhouse in the back. It is another thing, however, to explain to people today, whether they remember kerosene lamps or not, that, in a pre-electric light era, the creation of illumination always meant an expenditure of time and physical energy at least as great as that of lighting a match which is already several times more than turning on a light switch—and the vast majority of times meant an expenditure of physical energy far greater than that, an expenditure, which, to be efficient, was embedded in a social schema that involved getting candles, fuels, regularly trimming wicks and cleaning the glass chimneys, chopping wood and stoking fires, so that then even the casual creation of light in such an age was an entirely different social operation from what it is today. One might even say that, in such an age, light could not be casually created. Light was at the nexus of a great deal more physical energy and daily planning. Thus, because of our vastly different relation to it, light itself was a different social object from what it is today. And thus, every mention of light, in any text from that period, whether it be in the deadest of hackneyed metaphors or in the most vibrant and vivid poetry, is referring to a different order of object. What we have begun to explore here, of course, is the discourse of light. It is the discourse that, explored in enough detail, can reinvigorate the evil, distant, flickering lights that haunt American writers from Nathaniel Hawthorne to Ambrose Bierce, even as they turn into clichés in the later writings of Lovecraft; we must remember that initially such lights usually meant fires in the distance—forest fires or homes caught from some light source (got out of control), which, at the time, was always a flame source too. In the discourse of sexual roles, certainly the greatest material disturber of traditional roles was the spread, after World War II, in the late forties and early fifties (even more so than the Pill), of the home washer-dryer combination. Until that time, in any family of more than two people, the washing, hanging out by hand, and ironing of clothes took up a minimum of two full days a week; and that was what made it a foregone conclusion, as self-evident to women at the time as it was to men, that in order to have any sort of family, someone would have to have at least two days a week in a small family (of four, say), and three or more in a large one, to devote to this task. The reduction of the week’s laundry from two or three days to two or three hours was as traumatic to the discourse of sexual roles as the introduction of electricity and the light switch was to the discourse of light. We can say, of course, that things have changed—and have specifically changed in terms of race and sex. But I hope we have some way now of perceiving the extremely strong statement we are making when we say, for example, that the discourse of sex and the discourse of race have changed far more—catastrophically more—since 1956 (to pick an arbitrary date the year when the nation’s schools were, by law, desegregated) than has the discourse of light since World War II. 6. Interlogue Three. Etyonologically, the term “discourse” is a Latin word that refers to an old, oral, Roman race track. At a modern race track, spectators sit in seats on the outside of the track and look in on the runners. At a discourse, however, the spectators entered the central section of the track before the race, took their seats—or more often simply walked about from one side to the other—while the racers coursed around and around them. With such an object at its origins, it is hard to avoid metaphorizing. One entered the discourse and left it only at specified positions. The discourse encircled one; it surrounded the spectator, moving around and around him or her. It is also hard not to speculate on the nature of its initial shift into metaphor. Though it’s anyone’s guess as to how the discourse became a metaphor for reason, understanding, and ratiocination, since discourses were places of much betting, it’s probable that the kind of head scratching, the touting up of odds, and the endless speculative conversation on the merits of the racers characteristic today of horse-racing tracks were a part of daily life at the discourse and thus prompted the metaphorical shift. But even that’s speculation. No one knows for sure. Today, however, the OED gives us under “discourse”: 1. Onward course; process or succession of time, events, actions, etc. Obs. 2. “The act of the understanding, by which it passes from premises to consequences.” (Johnson); reasoning, thought, ratiocination; the faculty of reasoning, reason, rationality. 3. Communication of thought by speech; “mutual intercourse of language.” (Johnson). 1.4 Shorter Views And again: 1. To run, move, travel over a space, region, etc. 2. To reason. (To turn over in the mind; to think over.) 3. To hold discourse, to speak with another or others, talk, converse; to discuss a matter, confer. 4. To speak or write at length on a subject; to utter or pen a discourse. (To utter, say, speak or write formally.) But we are basically interested here in meaning number two within the cloud of rhetorical connotations meanings three and four have set in motion—around and around it. That arbiter of seventeenth-century prose, Sir Thomas Browne (1605–1682), wrote “Hydrophobia or a discourse of the sepulchral urns lately found in Norfolk” (1658)—that is to say, a discourse of, not a discourse on. The forty-seven-page essay represents Browne’s understanding, his reasoning around, his comprehension of the urns; it presents the information from life and letters the wise doctor possessed (or that possessed him) to bring to bear upon them that made the urns make sense—and, in its concluding thanatopsis, the sense that then soared from them. But, as I hope my brief example of Dunn has already shown, without the notion of discourse—or something that stands in its stead—there can be no sophisticated idea of history. 7. Discourse and Desire. To explore a discourse is inevitably to tell a story: At such and such a time, people did this and that; thus they thought and felt one thing and another. One of my favorite storytellers is a Frenchman named Raymond Roussel. The method he used to tell a number of extraordinarily far-ranging and imaginative stories, as he outlined it in an essay published shortly after his death in 1934, Comment j’ai écrit certains de mes livres, involved taking two phrases, word for word identical or different only by, say, one letter of one word, in which every word had at least two distinct meanings, and thus had two distinct meanings as phrases. His most famous example is: Les lettres de blanc sur les bandes du vieux billard and Les lettres du blanc sur les bandes du vieux pillard, which mean, respectively, “The white letters inscribed on the cushions of the old billiard table,” and “The white man’s letters written about the troops of the old bandit.” (Needless to say, the vieux pillard—the old bandit—in Roussel’s story is black.) Roussel saw his various tales as attempts to maneuver logically from one phrase, which we would find in the first sentence of his tale, to the second, which we would find in the last. En route, again and again, Roussel constructed incidents around phrases that had a more or less self-evident meaning but that could be reread to mean something else (“What do you do with a stiff neck?” “What do you do with a stiff . . . neck?”); I have always taken the fact that the tales of this wealthy French homosexual eccentric—when freed from the constraints of ordinary narrative discourse by the systematicity of his eccentric method—again and again swooped into the subject of race, of blacks, of Africa (Parmi les noirs, Impression d’Afrique) as a cultural index of just what a pervasive discourse race was for Europe—just as you will find, if you try the exercise in English, the secondary meanings so often have a sexual side. The discourse of race is intimately tied to the discourse of sex; the term race, until the late eighteenth century, meant family—specifically a large, ancient, powerful family, such as the Sforza race, the Medici race. When Leonardo wrote of the “Ethiopian races” in the notes he made on “Foetus in the Womb” sometime between 1510 and 1512, one of the reasons for the plural, races, is that, within the discourse of the time, what he was saying, denotatively, was “the Ethiopian families.” The notion of “race” as we know it would seem to begin in an anxiety to locate a unit, still mediated by heredity, larger than the family yet somehow within its conceptual economy, but not coextensive with the nation. And there is no way to have heredity without sex. But even while we have spoken of the rhetoric of sex, and explored some of the relations of those rhetorical figures, we have stayed, till now, purposefully away from the idea of desire. Desire is a very scary and uneasy notion. Its mark is absence. Accordingly, a positivistic culture frequently finds itself at a loss to explore it or elaborate its workings. The two doctrinal principles that most of us have access to come respectively from Freud and his most astute reader, Lacan: Said Freud: Repetition is desire. Said Lacan: What one desires is the desire of the Other. There are, of course, other ways to tell stories besides Roussel’s. Roussel expended extraordinary imaginative energy to make sentences that were phonically all but identical mean different things. But suppose we tell two apparently different stories—and try to elaborate a discursive structure in which they can be seen as one. Despite having a daughter, I come to you as a gay black male. But it is a reasonable assumption that some straight white males linger somewhere in my heredity. I find straight white males interesting—and sometimes, personally, sympathetic. A few years ago, I wrote a book, The Motion of Light in Water," an autobiography that tried to delineate for me what it meant to grow up in an American city as a black, gay, male writer of paraliterary fictions. In the book I talked very openly about my own particular sexual experiences and sexual fetishes. I assumed that the book would be most interesting to others in marginalized positions, vis-à-vis those straight white males who demonize so much of marginal discourse. The book received its share of approbation from black readers (female and male), white readers (female and male), and gay readers (female and male). Nevertheless, by far the largest number of people who have come up to talk to me about it—on more than one occasion now, after one or another lecture such as this—have grabbed me by the shoulder, dragged me into a corner, sat me down, and begun to tell me their problems, then asked me, with great concern, what, from my marginal position, I thought they ought to do about them, are straight white males. One would almost think they felt empowered to take anything the society produced, no matter how marginal, and utilize it for their own ends—dare we say “exploit it” —certainly to take advantage of it as long as it’s around. And could this possibly be an effect of discourse? Perhaps it might even be one we on the margins might reasonably appropriate to our profit or perhaps some of us already have. Most of their problems, of course, involved their relations with females—some white, some black, some gay, some straight. I have heard an extraordinary range of stories—and what these fellows are attracted to, oh my women friends, is amazing. Some want women of one race, some want them of another, some want women with glasses and some want women who are overweight, some want women with high IQs, and some want women with narrow shoulders set slightly forward—indeed, the range of tales I have heard from these fellows since 1988 when my book was published is enough to make the variety of vanilla heterosexual male desire seem a seething pit of perversions quite as interesting as any to be found in any S&M bar, lesbian, gay, or straight. But despite that range, I find myself again and again making the same rhetorical intervention. For here we are centrally sunk in the Discourse of Desire. What again and again I find myself saying to these men is: Can you utter the simple statement to the troublesome object of your desire: “I like you, do you like me?” And what is this terror of rejection that is so strong that it almost invariably drives one half, the other, or both of these enunciations out of the realm of articulation? Doubtless you can understand why both paired clauses are essential. If you cannot say, “I like you,” she will simply never know. If you cannot follow it with, “Do you like me?” you will never know. More to the point, if you cannot say, “I like you,” she will never know you have any emotions. And if you can’t say “Do you like me?” she will be sure, probably rightly, you are unable to evoke any interest, care, or concern with hers. This alone is why, “I like you. Let’s fuck,” does not accomplish the same communicative ends. In three out of four cases, these fellows will eventually ask: “But why doesn’t she say it to me?” To which I answer: “That is not the point. You’re the one who claims to be in pain. What are you going to do about it—for what I tell you is as likely to get you out of it as anything else you can do. It is certainly more effective than waiting in silent agony or clinging about in over-energetic exuberance for her to see through your sedimented silences or eruptive vulgarities your central yearning self.” I say this rather gently, of course. For one thing one learns in fifty years is that, though most of us eventually learn to ask, more or less, for what we want, it is always more or less impossible to ask for what we need. (If we could ask for it, by definition we wouldn’t need it.) That can only be given us. Finally, we are left to conflate, inarticulately and by our behavior alone, to make sure there is as much of it available in the landscape as is possible, in the hope that, eventually, we will be fortunate enough to receive some. But I have known a number of women who, when a man became interested in her (when he manages to communicate the first part of that oh so important “dip” which, wait around through whatever number of dates and get-togethers they feel are reasonable, for the second part—for the other shoe, as it were, to drop. And, when it doesn’t, they break off the relationship secure in the fact that there are leaving a situation where, for whatever reasons (at this point, the why is no longer her concern), their own feelings will never really be solicited—probably about anything. I recall one young man, deeply in love with a woman who seemed, certainly, fond enough of him to accept dates with him and TV viewings with him. He asked my advice on several occasions. “But does she like me?” he wanted to know. “Why don’t you ask?” I suggested. “I mean, I know she likes me. But does she like me?” “Again, if you don’t ask, you may never find out.” “I’ve told her that I liked her,” he complained. “Without any,” I said, “are: ‘I like you, do you like me?’ Of course.” I added, “if you ask, you risk the possibility of being told, ‘No.’ But isn’t that better than having to wait and wonder and not know for who knows how long?” When, after much rhetoric, he allowed as how it was, I thought the problem finally reduced to that never simple matter of gritting one's teeth and indulging in that terrible bravery that has to be breached in one form or another in every situation of desire. But a few days later, he was back. "I can't ask her," he declared. "You're that frightened of being told, 'No'," I asked, "that you would give up the possibility of being told 'Yes'?" "It's not that. It's because of what it would mean if I asked her." "What would it mean?" I asked. "It would mean, like, well—and here, I hope what becomes clear is the structure of the discourse in which we have been involved all along—"it would mean, somehow, that I was insulting her. That she was the kind of girl who was used to guys asking her, all the time, if she wanted to go to bed with them, if she liked them—it would mean like, well, I thought she was some kind of whore. And I couldn't stand that." "You mean," I said, "that if she had any sexual feelings for you of the sort that you have been regaling me with for the past six weeks, that have been destroying your sleep and plaguing your dreams, she would be a whore." "Well, like, no." "What about," I said, "like, yes." "Well, like it," "But not exactly it." "Like it, close enough," I said. The young woman broke off the relationship after another week. And wisely, I suspect. But I hope this tale alone is enough to suggest what a violent rhetorical intervention in the discourse of patriarchy, with its saints and whores (for that of course is the discourse we speak of here), the simple bipartite statement and question, "I like you. Do you like me?" represents. The discourse of desire, at work throughout the discourse of patriarchy, maintains such a situation, with its nebulous orders—want, need, and desire itself—notoriously impossible to pin down. For as soon as one systematically relates them (say, in the provisionally brilliant Lacanian schema: When all the elements of need are satisfied in the situation of want, the remainder is desire), ordinary language, with its italics and special emphases, manages to displace them soon enough so that all we are left is a memory of a momentary bit of rhetorical brilliance. Well, that is the first story I tell. But sometimes I tell a second story. Though I assure you, for all its radically different sound, it is as close in meaning to "I like you. Do you like me," as the opening and closing phrases of a tale by Roussel are close in sound. That tale is the dark knowledge my own life in the margins provides. Very simply, that second story runs: "The desire to be loved is sadism. The desire to love is masochism." To unravel the track from one to the other in the complex Discourse of Desire—to show that both inhabit a single discourse—is to evoke the Freudian notion that the realm of desire is the mirror realm of ordinary motivations. Freud told us that a perversion was the opposite of a neurosis: In the childhood machinations of psychic development, either we sexualize something or it becomes a neurotic character trait. To take pleasure from imposing your emotions on another person is sadism—a much easier translation to follow. But then, what else is the open, pleasurable, sincere, and aboveboard statement: "I like you?" Isn't that, if it's sincerely stated, a pleasurable imposition of one's emotions on another, and thus, when it is shot through with desire, a terrifyingly difficult enunciation? To take pleasure from the emotions of others over and above your own is masochism—an equally easy translation. What else then is the open, pleasurable, sincere, and aboveboard request: "Do you like me?" Again, when such a question is shot through with desire, isn't its asking equally terrifying? For you must have noticed—by now, certainly—that while some people are afraid of saying one, they are terrified of speaking the other—terrified to the point of sweating, heart-pounding, dry-tongued paralysis. And the difference between ordinary fear and terror is the difference between the social fear of sexual rejection and the totality of the universe-obliterating failure of both the self and the other that hones among desire's ancient and hideously deep foundations. Certainly we would stop our interrogations and discursive translations with the glib observation that every relation to start pleasurably, then, requires a little healthy sadism, a little healthy masochism—on everyone's part. But it is that notion of pleasure, and its dark relation to desire, that completes the identification of the tales. For, again, we all know—and know that the assignment has no necessary relation to who has what genital configuration—that there are simply too many people who, though they can manage to handle either one of those paired clauses are absolutely broken before the other. There are too many people who can tell you what they want but who are constitutionally incapable of responding to what someone else might want. There are too many people who are endlessly concerned with what others want but seem to have the same constitutional inability to articulate their own wishes. Again, the mark of desire is lack—and (pace Freud) repetition. So that once again, if you want to be loved to the intensity of desire— so that you seek that situation out again and again, so that the love of someone else inflames you, so that even another’s miming of the emblems of such a situation is enough to excite, so that the form of anothers love is a lack in you that, no matter how many times it is ful- filled by whatever act of love, it can never be finally and wholly sated, be- cause it is the form of your desire itself, then your behavior in the world to acquire what you seek must fall, one way or the other—to the extent that it is in excess of any real possibility—into the forms of sadism. And if what you want is to love another, again to the point of desire— so that you seek out opportunities to do so again and again, so that the possibility of another to love is what inflames you, so that anothers miming that she or he approves, deserves, demands that love is enough to ex- cite, that the form of love expressed in you is a lack, that, no matter how many times it is repeated by your behavior, can never be finally and wholly exhausted, because it is the form of your desire itself, then your behavior in the world to acquire what you seek must fall, one way or the other—to the extent that it is in excess of any real possibility—into the forms of masochism. "I like you; do you like me?" But the darker and more dangerous tale revealed beneath it is a clash of sadistic and masochistic imperatives: "The desire to be loved is sadism; the desire to love is masochism." For what are both these tales finally about? Power. Power is what distinguishes the psychic discourse of desire from the social rhetoric of sex. The rhetoric of sex commands enough strength to make a man or a woman walk the streets of the city for hours, to drive alone or in groups, searching for a proper gap in the communicative wall through which desire may somehow show. But desire, to the extent that it is a material and social discourse, commands power enough to found and destroy cities, to reform the very shape of the city itself, laying down new avenues and restructuring whole neighborhoods within it. And desire—paradoxically—is what holds erect that barrier to sex that so much of our rhetoric, as well as our actions of which finally rhetoric is a part, breaks against and crumbles. The power involved in desire is so great that when caught in an actual rhetorical manifestation of desire—a particular sexual act, say—it is sometimes all but impossible to untangle the complex webs of power that shoot through it from various directions, the power relations that are the act and that constitute it: You’re having sex with someone. Very well. Whose scenario is it? Who is exerting the most physical energy to bring it off? What is the social value assigned to each player in the particular act? What sorts of energy, action, and articulation are needed to transform or reverse any one of these? During such power analyses we find just how much the matrix of de- sire (the Discourse of Desire and the matrix of power it manifests here and masks itself) favors the heterosexual male, even if there is no such actor involved. Whoever is doing what the heterosexual male would be doing usually comes out on top. Though his 1915 footnote makes per- fectly clear that, by the use of the word "masculine" he simply meant "ac- active," this may nevertheless have been part of the thrust of Freud’s state- ment: "that libido is invariably and necessarily of a masculine nature, whether it occurs in men or in women and irrespective of whether its ob- ject is a man or a woman." It is a statement that, if taken in the biological sense (which the same footnote excludes from the reading), is precisely as ridiculous as "the urge to sneeze is invariably and necessarily of a mas- culine nature, whether it occurs in men or women." What we on the margins have been most able to appropriate of this discourse is the power analysis that so much of the discourse of patriar- chy is structured precisely to mystify. In many cases, its demystification is precisely what has allowed us to survive. 8. Discourse contra Discourse. Rich with its materiality and explicative force, the idea of discourse that I have been putting forward is an exciting one and a seductive one to those first coming to history. In 1849 the postage stamp was introduced in England. Before that date, when a letter was sent, the recipient paid the postman on delivery. After that date, the sender paid—and suddenly letter writing became a species of vanity publishing. To know this is to be able to make sense of a range of sentences found in dozens of early nineteen-century novels that often appear as some form of "From then on, she would never re- ceive his letters." Specifically what that means is: she refused to pay the postman for the letters—and they were returned to the sender. At once, we have an explanation for questions ranging from why so many letters from before that date were preserved (what you paid for you kept), to why there was no junk mail before then (who would pay for it?), to why the correspondents themselves were often so witty (if you knew you had to make your letters worth the three or four pence your recipient had to shell out—eighty or ninety cents at todays prices—you were likely both to write at length and to try to have something to say). We begin to see such letters fitting into the social matrix very differently from the way our mail does, and we begin to develop a postal discourse. In 1851, the lead paint tube was introduced, which meant that suddenly artists could keep with them amounts of paint much smaller than in the pig-bladders full of hand-ground pigments, traditional since before Leonardo. With the invention of the metal ferrule in the same few years, which held the bristles to the brush and flattened them, it became far easier for artists to travel from their studios and paint nature; the average size of the canvases suddenly shrank; the possibility of an amateur painter became real. Hordes of painters now descended across the landscape—and Impressionism was the result, as dependent on that bit of soft lead foil as on any aesthetic considerations. The relation of the artist to society, through all the economic changes from that technological development, which, through that change, changed the relation of society to art, resulted in a major reformation of the discourse of art. In the early 1870s at Bayreuth, Richard Wagner, at the opening of that concert hall, so as not to break the atmosphere created by the music, for the first time in Western concerts initiated the convention that audiences not applaud between movements of symphonies or string quartets; now, as the Bayreuth Festspielhaus moved on to the production of operas, he put up signs in the lobby that no talking was to occur during the performance; and, to help the audience concentrate on the music and stage action, he turned the house lights off during the performance of an opera, so that the audience watched the performance enveloped in the dark, with light only on the stage. Elizabethan theaters had performed under sunlight at the open-roofed Globe and Blackfriars Jacobean theater, as well as the theater of Racine and Molière, the later theater of Mozart and Beaumarchais, were all theaters of light. But when, under Wagner’s direction, the house lights were lowered—and the tradition spread from Bayreuth through all the opera houses and finally all the theaters of the West—a different relation was marked between art and audience, a change in the relationship, which had been growing throughout the rise of Romanticism, a change that we can read in metamorphoses of theatrical discourse. The initial excitement from the discovery of material changes controlling discourse (these changes are often so total we do not realize they render one side or the other of a cultural discontinuity set in place by money and technology: the new and modern gas lamps, say, by which Wagner’s Festspielhaus was lighted and darkened, as well as the great steam curtain that produced the billows of effective stage fog, which, as George Bernard Shaw noted in his recollections of the Ring performances of the late 1890s, “made the theater smell like a laundry”) at first produces a kind of vertigo in the young intellectual newly alert to the complexities of history.11 It is perhaps, then, time to cite the example of the intellectual figure most responsible for the current spread of the notion of discourse as a historical modeling tool, Michel Foucault. When we have been considering the problems raised by our own studies of discourse, nothing is more exciting than the essay he published at the end of his methodological study of the problems of discursive study (The Archaeology of Knowledge, where he tears down his own former notion of “épistémès” and replaces it with a theory of discourses, utterances, genealogies, and apparatuses), “L’Ordre du discours” (“The Form of Discourse”), rather frightfully translated as “The Discourse on Language.”12 In the course of this essay, while he exhorts us to look for chance, discontinuity, and materiality, Foucault warns us away from the idea of founding subjects, originating experiences, universal mediation, and the tyranny of the signifier. I think Foucault would be the first to remind us that, in the midst of that most anxious paragraph on our Leonardo drawing, concerning the paradox of Africa as Italy had to see it, there is that anomalous “female seed.” Look at it, research it, seek it out in a range of synchronous and diachronous texts, before deciding precisely what kind of anomaly it is. And the current discourse of patriarchy and the Discourse of Desire that suffuses it, and—now and again, here and there at its several points—seeks to subvert it, is just as materially grounded as any of the historical ones I have cited. Similarly, and perhaps more importantly, none of the historical ones, when studied in their specificity, their discontinuity, their exteriority, are any less complex than we know from our first-hand experience the discourse of desire and patriarchy to be. 9. Interlogue Four. From the array of voices with which discourse addresses us, one insists: “Return a moment to the homilies with which, at the end of section seven, you effected your utopian turn, and allow me to ask: Why is it necessary for sadism to be about all these emotions? Why can’t it simply be about pain? Does it take an active anticipation of your argument on my part to provoke you to the cool reason that your text keeps putting forward as your stance? Soon you will be explaining that the analogous relation between the sexual and the social that is mistaken for causal is, most generously, the structure of superstition and most oppressively the structure of oppression itself. Why, then, must you make this spurious analogy between the psychological and the sexual? You yourself have argued that The Authoritarian Personality by Adorno and the Frankfurt Group first validated the notion of the causal relation between the behavior of the Nazi bureaucracy of the thirties and forties and sexual sadism, and thus functions on exactly the same level as the discursive origin of an oppressive structure as political as the medical institution of homosexuality that allows heterosexuality itself to come into existence. Would you actually argue that I am, whether with my breasts thrust into black leather or basket heavy in a studded jock, the One Always There, who, when everyone else is redeemed, can be thrown to the dogs, at the eye of the patriarchal cyclone you’ve already located as the straight white (need I add?) vanilla male? As you make your accusations of appropriation, surely you’ve noticed the totality of the structure you excoriate: with Jung, he steals, in the form of the anima, whatever from the straight female; with the rhetoric of ‘latent homosexuality,’ he appropriates all he could possibly use from the real thing: in the emergent rhetoric of transsexualism, as the center of discourse, as he learns that most transsexuals are lesbians anyway, he takes over lesbianism for himself (as he has it already in any number of lesbian scenes in any number of pornographic films); and now you’d toss him my whip and chains, along with that Freudian reduction that claims, in a patriarchally produced scarcity field of sexually available females, the only way he can get by is with a little ‘healthy’ sadism! Hal! I’ll take the sick kind, thank you very much. No wonder he comes out on top. That’s simply where you’ve placed him! Would you settle for some argument in which everyone, even your straight white vanilla male, needs his very own Other—and claim that is, somehow, something new? The discourse—your privileged term—has been contoured for generations: Jew, forget the insults that face its text, and look at The Merchant of Venice. Woman, forget the insults and look at Madame Bovary (“sitting like a toadstool on a dung heap,” writes Flaubert in his novel). Sissy, forget the insults, and look at Hitchcock’s Frenzy. Gay black male, look at Mapplethorpe’s Man in Polyester Suit. There’s something there (haven’t we all been told?), universal, transcendent, aesthetic—good for you. Just swallow; and always insist to yourself that what must be swallowed is something other than the self-respect that is not, of course, his. Well, neither my sadism nor my masochism runs in that particular direction. But even by talking for me this much, you excite me to the position of that dark and eccentric figure lurking at the horizon of Romanticism, speaking all you dare not resist. Well, your cowardice is not masochism. And my articulation is not sadism. Don’t think because you speak, or rather mumble, in my stead, I can somehow be silent or you can silence this rhetorical fistulae. “What would happen if you really (i.e., politically) extirpated that metaphoric idiocy from your proposed discourse of desire—idiot not because metaphors are themselves the idiot things Western philosophers have been claiming since Plato, but because metaphors badly formed are the discursive elements that mystify and stabilize oppressive systems. Describe for me the picture book about the little bear who discovers the pleasures of pain, of degradation, and who learns the delights of giving it, receiving it. (Let’s get really radical with your white-out and your felt-tip!) You and I might even suggest, one to the other, it teaches that you must make sure to exercise such pleasures only with someone else who appreciates it, complete with ‘safe words’ for ending sessions and ‘talking out periods’ at the start (you can find such in any reasonable manual of S&M practices with which, today, I must vacate my personal reason). There’s your role model, you’ll say. There’s your certificate declaring you a member of the greater society of sexual variation. And, my friend, when such picture books are neither laughable nor politically correct, but as common as Candies, then, rest assured, I shall tell you not that I accept your Discourse of Desire in all its utopian naiveté; rather, that will be the very moment I shall at least and at last be able to hold up both and demand why my desires must be policed in the one, while his are still so untrammeled, unmarked, and free that they need not even be mentioned in the other—the reticence creating the margin across which he creates himself by creating me but across which, yes, I plunder him regularly. (Oh, sing it, honey: ‘Not only is it a boy bear, Daddy! It’s a straight, white, heterosexual, vanilla, boy bear—in case you hadn’t noticed.’) That will be the moment when at last and at least I can prove to you that precisely at the point I would seize my desire in its freedom, there you would name my particular form of it the core and kernel of all policing the embarrassing Hegelian wish to rule and be ruled. As Freud and Marx gave you tools to analyze this on its own terms, you insistently equivocate one set of causes with the other and leave democracy a consumer travesty of itself through the people’s ignorance of what this ruling and being ruled is really about—then you demonize it by claiming that, whenever it rises into articulation clear enough to signal conflict, somehow its currying political torture is itself one with sexual torture, and lay it at my terrifying, cloven foot. “Well, I’ll tell you. Anyone who believes your vaunted power relations in a session of consensual sexual torture are the same as those in a session of imposed political torture is simply and brutally ignorant of both—and deserves (the political discourse of the time demands—as ‘shave and a haircut’ demands ‘two bits’) whatever happens . . .? ‘Him or her, my friend, no more than I.’ ‘No one deserves whatever happens.’ That deserving can only be enforced. “Ruling and being ruled, the very deployment of political power, the walls of reality and every attempt to scale, breach, or reposition them—that is the material ground and limit of your discourse. Who speaks now is precisely the devil that discourse has placed here to frighten you off. the very question—who lied to you that ruling and being ruled are causally entailed with my desires, just as you lied to him that, in his cowardice, he is as strong as I. But learn, mon semblable, mon frère, not that I am you; rather that you are not me—even while the organization of our oppressions may be the same. Learn, too, by so learning, how different what all your patriarchal logic tells you is an identity is from the cored out, resonant hollow of our differences. “Those discursive identities are there to kill me, not you—whomever you, the privileged speaking subject who allows me only to function as your ventriloquized puppet, are.” 10. Interpretation and Perception. In the discussion of discourse a concept eventually must arise. It seems to be a part of the modern discourse of discourse itself. It is given by the phrase, “Interpretation precedes perception.” To understand it, we might start with an alternate narrative as to how humans perceive things. This alternate narrative of perceived meaning commences something like this. We begin by perceiving abstract colors, shapes, sounds; eventually, by relating them to one another, to other sets of abstract colors, shapes, and sounds both temporally and spatially, we build up a picture of objects, events, and finally of reality. Once we have an objective model, we interpret it and ask what we can understand of it. The problem with this story of perception is that, from both neurological study and introspection, it just doesn’t seem to be the way the brain—or the mind—is set up. Interpretation of vision begins, for example, as soon as light hits the retina. Cats see horizontal lines and vertical lines with different nerve bundles. And some nerve cells in the frog’s eye respond to small, dark moving dots, which might be any one of the range of edible bugs, while other nerves respond to broad patches of general color, which might be land, lily pad, or whatever. There may, indeed, be electrical impulses moving around the brain that are signs for abstract colors or even shapes. But by the time they register in anything like “mind,” interpretation of what they are has well begun. Introspectively, we humans can supply our own evidence for the priority of interpretation over perception. I recall waking up last autumn in my Amherst apartment, in that dim period when the sky beyond the bedroom and bathroom windows was still deep blue. Looking for my hairbrush, I wondered if for some reason I’d left it in the kitchen. And so I stepped in through the kitchen door— Ah, there it was, across the room on the small triangular table by the sink, its black plastic handle sticking out behind the edge of a colander left there from last night’s spaghetti. I took a step across the linoleum floor— But now I saw all this dust on the handle’s edge. Gray fluff was visible in three small heaps generally spread from one end to the other. I took another step, and what I’d seen as a black plastic handle with the long, three-peaked mound of dust on it, became the handle of one of my kitchen knives. The handle was black bakelite. What I’d seen as dust was the light glinting off the three steel bolts that, level with the bakelite, held the blade in place… The point here is that often we do not have enough perceptual information to make out what something is; but in such situations, we do not perceive—at first—that we have only partial information. We perceive some thing; then, sometimes only a moment later, we perceive some other thing that contradicts the first. Those contradictions are the sign that we eventually learn to interpret as incomplete perceptual information. Eventually, if the contradictions go on long enough and will not resolve, we perceive an abstract color or shape, whose substance or full form we cannot know. But such a perception represents an even higher order of interpretive complexity than the perception of concrete objects and events—rather than a simple and atomic element on which perception itself is grounded. Abstract entities are a discourse. The person or the small dog we catch out of the corner of our eye when we know no person or dog is there becomes, when we look at it fully, an overcoat hanging from a hook on the inside of the open closet door, the overturned shoe box fallen from the chair beside the bed. Though, faithful to that other story, we might even say, "I saw something that, a moment later, resolved into a coat, or a shoe box," the truth is that, however fleeting, the something was probably something fleeting but specific—not something in general. To become aware of this process is to become aware that some, if not all, of these mistaken perceptions relate to, if they are not controlled by, preexisting discourses. (Reason, memory, and desire told me I might find my hairbrush in the kitchen.) Once we accept the notion that we cannot perceive without already having interpreted what we perceived, however mistakenly, as something, even if our interpretation finally settles on the one we call the fact that we are seeing does not provide enough information to draw a solid conclusion about the object (and thus must remain in the realm of unresolved abstraction), directly we find ourselves asking such questions as: Did Leonardo really see a round womb? And, by extension, was that round womb of the order, say, of my black plastic hairbrush handle that I thought I saw across the room—or perhaps of the dust piled on the piece of black plastic that replaced it? The Rhetoric of Sex / The Discourse of Desire Bohanann sought solace awhile with Hamlet. But finally she found herself in the reception hut as well, faced with the request that she tell a story. And so it is the story of Hamlet that she decides to tell, sure that its universal resonance will sound out as clearly in the Tiv as it might in an Oxford seminar room. But problems of interpretation, perception—and discourse—arise immediately. While the tribe has an evolved and subtle concept of magic, knowledge, madness, and the relations among them all, Bohannan’s tribe has no concept of ghosts. In the tribe, there simply were no stories of the dead returning—either believed or accepted as fantasy. Thus, the very first scene of Hamlet’s father’s ghost on the battlefields registers with Bohannan’s hearers neither as a frightening event nor as an emblem of the supernatural simply to be accepted—but as a narrative mistake. Obviously what she must mean, they explain, is that it is an omen sent by a witch. Because if you see a dead person actually walking around, you can be pretty sure that’s what it is. But as for its being the soul of the dead, that’s just silly and obviously, then, narrational error. (“But, Daddy, it’s a boy bear . . .”?) The tribe’s term for “wise man” and “witch” were the same. Thus, establishing Horatio’s position as a benign scholar was rather difficult. In that tribe there were strict proscriptions about what was appropriate to the various generations—proscriptions that served to determine what jobs as well as what topics of concern were appropriate to each; as well, those proscriptions served equally to discourage intergenerational violence: Parents did not strike children. Children did not strike parents. If, in that tribe, someone had problems or complaints about you, from childhood on they presented them, either up or down the scale, to your age mates, by whom you were then judged and, if necessary, punished. Intergenerational conflicts there were likely to be the stuff of mild irony or appalling vulgarity. But the same proscriptive institutions prevented them from being the center of comedy or tragedy. Thus the whole Oedipal scenario so much fiction in the West depends on—the conflict between generations—had for Bohannan’s hearers a somewhat sleazy air; and certainly no tale that appealed seriously to them could resonate as the major conflict behind all cultural progress, somehow—in this story—gone away and gotten terrifyingly and tragically out of control. Rather, it seemed an unnecessary nastiness that ordinary social institutions ought to have obviated. Hamlet’s status as a hero was immediately in question by all the village auditors. Finally, the borderline incest Claudius and his sister-in-law Gertrude... indulge to Prince Hamlet's consternation was, in this tribe, de rigueur. No, certainly you didn't go around murdering your brothers. But if your father died, then simple politeness said his brother should marry his surviving wife or wives. And if he was suspected of such a murder, it's for your father's age mates to decide—not for you to do anything about. Hamlet's madness caused equal problems—since everyone knows that madness is always the result of a witch at work somewhere. What's more, the witch has to be a male relative on the victim's father's side. (Everybody knows that.) Since he was Hamlet's only male relative in the story, obviously Claudius was to blame— Well, yes, Bohannan had to agree. He was. But with that as the explanation for why, did any of the Western tale really remain at all . . .? Polonius's murder behind the arras was also completely revalued in this tribe of ardent and experienced hunters, where, just before you throw your spear, you must call out, "Gamel!" whereupon anyone in the vicinity who can't see where you're throwing shouts out so that you don't hit them. When he sees the arras move, Hamlet calls out: "A rat!" As one of the hearers commented to Bohannan: "What child would not know enough to shout out, 'It's me!'" As the tale goes on, to turn it into a "good story," a logical story, a story where the actions were believable, where the motivations made sense to them, Bohannan's audience distorts the tale into a comic cascade whose humor for us is only subverted by its endless intricacy: Hamlet's forging of the letter that gets him out of trouble with the King of England and gets Rosencrantz and Guildenstern beheaded in his place sounds particularly suspect from Bohannan, since she, having already acted as the scribe for the tribe in its relations with the outside world, has already had to tell many of the same listeners, when they'd come to ask her to change various amounts on various bride-price documents, that such forgery is impossible and would immediately be detected. If Bohannan can't forge a letter, how come Hamlet can? But it is only by taking over the tale and turning it into an unrecognizable concatenation of unrecognizable people in unrecognizable situations operating through unrecognizable motivations, and finally of a significance wholly incomprehensible to us, that Bohannan's tribesmen can make any sense of the tale at all. (Laertes must have driven Ophelia mad and killed her, of course, since he's the only male relative of her generation mentioned in the tale. His attempt to avenge her death? Obviously a cover-up for deeper, more logical reasons.) And when their interpretation does manage to offer a recognizable evaluation, it is for such a different web of reasons that the similarity is really an accident rather than any shared cultural resonance. An old man, gathering his ragged robe around him, finally tells Bohannan: 'That was a very good story. You told it with very few mistakes. . . Sometimes you must tell us some more stories. We who are elders will instruct you in their true meaning, so that when you return to your own land your elders will see that you have not been sitting in the bush, but among those who know things and have taught you wisdom.' What Bohannan has learned, of course, is that the universal is nothing but an intricate relation of specificities. And what's more, the "universal" is quite different and distinct, cultural locale to cultural locale. The discursive wisdom that Bohannan's tale can teach us today concerns what Foucault, in "L'Ordre du discours," calls "the tyranny of the signifier." That is the notion, all too easy to fall into if one has not moved about among radically different discursive structures, that a single recognizable event, a single recognizable object, or a given rhetorical feature will have the same meaning no matter what discourse it is found in. This is the notion that impels the so-well-intentioned cultural imperialism of symbol explicators such as Jung or Joseph Campbell, who again and again seem to feel that when they find a dragon or a mandala in two widely separated cultures, somehow they have discovered the "same" or a "shared" symbol. For me this notion exploded on my first trip to Greece, in 1965, where I quickly learned that the palm-leaf beckoning gesture by which North Americans say, "Come here," there meant, "Good-bye." The palm-down flapping of the hand by which we indicate "So long," there meant, "Come over here." The sideways movements of the head by which we indicate negation there meant, "Yes." And the single up-and-down movement of the head, which here is very close to our nod of agreement, there meant, "No." If the very signifiers for yes, no, come here, and good-bye could all reverse between, say, Paris and Athens, then the apprehension of the "same" signifier in China and Mexico, in Texas and Thailand, in India and Guatemala, must mark the existence of cultural specificity—discursive difference, rather than some bicultural obliterating, transcendent "universal"—almost always functioning in the service of some structure of economic exploitation. Bohannan's tale is structured to throw into relief a limit of discursive disjuncture. And that, as we have noted, is what we experience when we read Roussel. That both use Africa as their background is, itself, controlled by the racist discourse of the West. We must not, for a moment, ever think, therefore, that our exploration of discourse is free, complete; rather, those explorations are always policed by discourses already set in place. 12. Observation and Articulation. One day in a Central Park playground in the summer of the same year in which my daughter had learned the discourse of children’s books, around a fountain and having shed all clothing an hour back, a handful of kids in my daughter’s play school group all clustered around a three-and-a-half-year-old girl named Mischkatel, who enthusiastically proposed a game to Sascha and Iva and Nord and Aiesha (this was, recall, the seventies): “Let’s see who can pee-pee the farthest!” And while I looked on—I confess, surprised—the five of them stood to the ankles in the water at the fountain’s edge—and let whiz. The girls, of course, without exception, won—since, in general, the urinary track exits from the body proper horizontally, or even with a slightly upward tilt. And since every one was just standing there, letting fly, the little boys, who dangled a bit, had not thought to use their hands to guide their stream and so generally watered in a downward slant rather than straight out. Mischkatel, Iva, and Aiesha all more or less tied and left the two little boys, Nord and Sascha, frowning down at their self-evident lack and symbol of powerlessness, marking the male site of greatest physical vulnerability. In a society where children play regularly naked with another, this can not be an anomaly. But I had to ask myself, sometime later, if I was empowered—as it were—to see this by a situation from not a full decade before, when, in 1969, I had lived in San Francisco, and a nude sunbathing and beer fest had started on the tarred-over roof of our Natoma Street flat. Eight or half a dozen of us were sitting around, naked, drinking bottle after bottle of beer, when, as several of us already had, a young woman got up, went to the back of the tar-paper roof, and proceeded to urinate off the edge with as high-flying an arc as anyone might want. I remember how cool we were all being—in what, I suspect for most of us, was some astonishment. A young woman was about to speak, when a young man asked (another white male appropriation, no doubt): “How did you do that?” Her answer was classic: “You aim, stupid.” Then she proceeded to demonstrate how, with two fingers of one hand in a V, turned down over the upper part of the vaginal crevice, one could control the direction of one’s stream. I am a writer. Needless to say, I incorporated the scene (or rather one based closely on it) in my next novel. Some months after the book appeared, I received a letter, signed by a group of five women in Vancouver, that said, in brief: “Thanks.” But the tale has its converse. In the late sixties a cheap series of charter buses ran back and forth between New York and San Francisco, generally called “The Gray Rabbit.” By the end of its run, the restroom at the back of the coach had long since lost its door. In general, with the rather free-wheeling young men and women who availed themselves of the $45 one-way fare, this was not a large problem in itself. What became a problem was that, after the first day of the trip, because of the lack of springs and the back roads, thanks to the men on the bus the restroom became pretty foul. And the women on the bus didn’t like it. The problem was eventually solved by a woman driver, who took a length of a two-by-four, a hammer, and some nails and fixed it into the doorway at little above chest height; she put another one behind it so that there was simply no way to approach the commode in a fully upright position. On the first of the two-by-fours she hung a sign: YOU DON’T SIT, YOU DON’T PEE! The problem was more or less solved. But the point is that women can, and some do, urinate standing up; and men can, and some do, urinate sitting down. As to arcs and distances, well, in the same conversation in which I asked my daughter about Corduroy, I asked if she remembered her infantile peeing contest. No, she didn’t, any more than she remembered the female Corduroy. But was that exclusion from her memory chance? Was it because that memory had not been stabilized by a pre-extant discourse? Men and women do what they do—that they’re comfortable doing. But the constraints on that comfort, on who does what and when, are material, educational, habitual—feel free to call them social. And where all three—material, educational, and habit—are stabilized in one form or another by language, we have a discourse. From such memories I turn to others that are so like the experiences that prompted Freud to his theory of “penis envy,” when my daughter, at age four, a year after her forgotten triumph in the park peeing contest, in imitation of me, would stand at the commode with her hands on her genital region and make hissing sounds. In another series of stories I wrote about that time, you will find the detritus—and pretty much my thinking—on all the incidents above. But is the reason such incidents as this not usually talked of—speculated over, theorized, included in our traditional elaborations of the way our culture works—because of some massive discursive exclusion? Are they simply not seen by most people because they take the form of the pear-like bulge in the upper part of the uterus—or are they simply nispereived as something else, like the mistake of a knife for a brush? Again, that is precisely the information the structure of the discourse that has prevailed up till now means that we can never have with any real certainty about the past. Again, that is what discursive exclusions do. But I also asked my adult daughter, not too long ago, if she remembers ever wanting a penis. "No," she said, with some consideration. "But I certainly remember, when I was four, wanting to urinate standing up. It seemed so much more convenient." A reasonable thought for a four-year-old who, at three, could—and had won a contest by doing so. 13. Interlogue Six. The material fact that has made it desperately important for people, when writing about sex, to write about what they have done and experienced and seen themselves, is, of course AIDS. This disease, which by February 1993 (this year), according to the always conservative statistics of the CDC, has killed more than 135,000 people in the United States, out of the more than 210,000 reported cases (1,800 of whom are children under the age of thirteen and 11,000 of whom are women), is certainly the largest material factor in the transformation of the discourse of desire and that transformation’s manifestation in the rhetoric of sex. It is painfully ironic that Foucault, who wrote in his 1970 lecture, "L’Ordre du discours," "We are a very long way from having constituted a unitary, regular discourse concerning sexuality; it may be that we never will, and that we are not even traveling in that direction" (233), died of AIDS in 1984—for AIDS has come as close to unifying certain strands of sexual discourse as it has come to fracturing certain others. Foucault also said, in a 1980 lecture at Stanford on political and pastoral power: "We must get rid of the Freudian schema. You know, the schema of the interiorization of the law through the medium of sex." He did not say we must get rid of Freud but only that we must get rid of a certain reduction—and I would add, distortion—of Freud’s critique of society that is too often justified by citations of Freud, usually at his most speculative: "the interiorization of the law through the medium of sex...." Well, what does this mean? It means an intellectual move in which the thinker notes some analogy between some aspect of a given sexual act, usually the tritest and most common one in a given culture (often our own), and some form of the culture itself or the usual psychology of those in it. At that point, the thinker claims the former as a cause for the latter, and this causal relationship is elevated to a transcendent affirma- tion of the universal and unchangeable nature—the law—of the social (or the psychological) through the power of the sexual. Nor does it matter whether the argument is: "Because men lie on top of women during sex, men will forever dominate women during...badminton tournaments," or "Because a fatal disease is now transmitted sexually, the whole of society itself must somehow be psychologically sick and doomed to destroy itself." Sex has become the medium through which someone declares a form of the social to be "natural" law rather than considering sex itself simply another social form. At this point, we should be able to recognize the same discursive structure—and the same misapplied logic—in them all. For this is the discourse, the reasoning, of sympathetic magic, pure and simple; it is as much superstition today as it was when in 1890 Sir James George Frazer described its practice in the initial chapters of _The Golden Bough_. And it mystifies and distorts any study of the material realities (i.e., the politics) to which both the sexual and social actually respond. But with that exhoration (a position implied in Foucault’s work, again and again) Foucault becomes easily identifiable as the enemy of all sexual spectators who would take refuge behind such superstitions, with their ideas entailed by the notion, as we usually characterize them today, that biology equals destiny. (The most recent and vociferous is, perhaps, Camille Paglia.) Similarly, Foucault had already been identified as the clear and present enemy by those who claim history is over, and that we have entered some posthistorical period (often designated postmodernism), where all discourses are homogenized and there are no discursive articulations to be found any more, thanks to the current invisibility of power; I mean, of course, the author of _Forget Foucault_, Jean Baudrillard.14 Well, Foucault also said: "While we sit discussing the word, power works in silence." But the idea that there is a nature—or a culture—outside of history, before history, or after history, to which somehow we have a clear access, partakes of a single discursive form. There seem to be at least two ways to highlight some of the structures of a given discourse. Both may boil down to the same thing. One is the critical observation of what is around us, precisely while on the alert for things that contravene what we expect. The other way is to suffuse one discourse with a systematically different discourse and watch the places where strain and tensions result. This, in effect, is what Bohannan does with her story of the story of _Hamlet_, and it is what Foucault does again and again in the range of his work, with his insistent systematicity that grids and grids and constantly tries to locate objects schematically within them, even while, as much as Derrida, Foucault himself eventually throws off his own gridding systems as too loose, too lax, improperly positioned, and necessarily displaced. This is what Roussel does in his fiction; his eccentric linguistic method, by which he arrives at his progression of preposterous machines, incidents, and relations, always gives us the feeling that narrative discourse as we know it is strained, near to the point of breaking, and thus becomes a palpable object in our experience of his texts. It is too wonder that Roussel was also a favorite storyteller of Foucault's and that his early study, published in English as *Death and the Labyrinth*, is certainly—and systematically—the best single study of Roussel currently available. 14. Conclusion. The last thing I want to speak about is a place where, indeed, the homogenization of discourses has produced an angering, murderous sexual rhetoric that fights the Discourse of Desire at every point—a social locus where two discourses that already suffuse one another must be separated out. I have already cited the mortality statistics; and, if we do not separate these discourses, those statistics may be a long, long time in leveling off their horrendous upsurge. For it was as far back as 1987 when I realized that AIDS had become, among my friends and acquaintances, the single largest killer, beating out cancer, suicide, and heart attacks combined. To my knowledge there have only been two monitored studies to date on the sexual transmission vectors of AIDS—certainly no more than two that have received anything approaching visible coverage. More accurately, there have been only one monitored study and one semimonitored study. That the studies agree as much as they do in their outcome is, then, surprising and heartening. But in my own informal survey, fewer than one out of ten AIDS educators knows either of the studies, of their results, or where to direct people to these studies who ask about AIDS. What is a monitored study? Well, other than intentionally experimenting with humans and the AIDS virus (which is illegal), a monitored study is the only way we can obtain information about AIDS transmission vectors that can in any way be called scientific. In a monitored study of sexual transmission vectors for HIV, a number of people, preferably in the thousands, who test sero-negative are then monitored, in writing, at regular intervals, as to their sexual activity: from the number of times, to the number and sex of partners, to the specific acts performed, oral (active and passive), anal (insertive or receptive), vaginal (insertive or receptive), anal-oral (active and passive), and what have you. At the end of a given period, say six months or a year, the same people are tested for sero-conversion. The status of various HIV positive and HIV negative people is then statistically analyzed against their specific sexual activity. Of the two studies that have been done of this sort, one by Kingsley, Kaslow, Rinaldo, et al., was published in *The Lancet* of 14 February 1987; it involved 2,507 gay men. The other, The San Francisco Men's Health Study, involving 1,035 men picked at random from a neighborhood having the highest AIDS rate in the city, was reported and described in a letter to *The Journal of the American Medical Association* of 4 April 1986. I call this last a semimonitored study because there the monitoring was done only twice, once at the beginning and once at the end of the study, and was in the form of a general survey, asking "What do you do in bed and what do you not do?" rather than the specific and regular tracking of Kingsley, Kaslow, Rinaldo, et al. Both of these studies report, quite interestingly, a statistical correspondence of 0 percent—not 1 percent, not 3 percent, not 8 of 1 percent—0 percent of sero-conversions to HIV positive for those gay men who restrict themselves to oral sex, unprotected, active or passive (147 men in Kingsley, Kaslow, Rinaldo, et al.; an unspecified number in the *JAMA* letter describing The San Francisco Men's Health Study). The statistical correlation between sero-conversions and receptive anal intercourse in both studies was devastating. Nor was there any statistical indication that repeated sexual contact had anything whatsoever to do with transmission. Kingsley, Kaslow, Rinaldo, et al. reported eight sero-conversions to HIV positive among men who reported only a single case of anal-receptive intercourse for the duration of the study. Should I have to point out that this renders the rhetoric of "repeated sexual contact," so much a part of AIDS education both before the 1987 study and since, murderous misinformation? Well, then, I hear an apologist for the status quo of (lack of) AIDS information say, maybe it applies to some other areas of sexual behavior besides anal intercourse? To which I can only say: "Tell me where." No: Many men who believed such rhetoric applied to anal intercourse and based their sexual behavior on it are now dead. It's that simple. There has been no dissemination of information of any monitored studies for sexual transmission of the HIV virus from and/or to women. I can only assume, after three years' research, that such a study has not been done. And with an epidemic that has caused more than 135,000 deaths in ten years, and 11,000 cases among women, this situation is a crime whose statistics are reaching toward the genocidal. A monitored study is a powerful discursive machine for producing a set of highly operationalized rhetorical figures—of the sort we call evidence in situations such as this. In a monitored study, is there room for mistake, or lying, or distortion? Certainly. But the knowledge obtained is still preferable to the alternative. There is, of course, another discourse that produces its own rhetorical array. A person is diagnosed HIV positive or with full-blown AIDS, and the doctor asks: "Any idea how you got it?" And the patient, possibly trying to think what he or she was doing sexually six months or so ago, possibly relying on what he or she already "knows," gives an answer. Logically, however, this cannot be evidence in an attempt to find out how AIDS is transmitted, if only because it presumes the answer is already known to the question we are trying to learn the answer to. Is it necessary here to stress that people, especially in sexual situations, will lie, will forget, or will misremember pears for apples or even hairbrushes for knife handles—for any number of discursive reasons, in a discourse that has undergone catastrophic changes without cease over the last ten years? Nevertheless, the information gleaned from this second discourse is regularly overlaid, called fact, and used to displace information from the first. Otherwise responsible publications regularly report that now 8, now 16, now 12 percent of men have gotten AIDS from oral sex, now 1, now 2, now 3 percent of men have gotten AIDS from prostitutes, when the most they can mean is that this is what a certain percentage of men, when diagnosed with AIDS, have said when asked, in a discursive field whose precise discursive form is that we do not know what vector possibilities (because they have not been adequately researched) and, thus, almost anything may be said and be believed. This, then, is the discourse of popular belief. Purposely leaving needle transmission aside, we "know" (that is, the studies that have been done strongly suggest) only two facts about the sexual transmission of AIDS: that it is not transmitted by oral-genital sex between men. And that it is transmitted easily and effectively through anal sex. Anything else we might say about its sexual transmission is all in the realm of superstition. Sometimes superstitions turn out to be true. But in a situation of such moral concern, what can be gained for the Discourse of Desire through this appalling and institutionally supported ignorance? Please: If you—heterosexual or homosexual, man or woman—are concerned about the sexual transmission of AIDS, demand of me that monitored studies be initiated, be rigorously overseen, and their results be widely disseminated. For the rhetoric of sex is complex; and the discourse that organizes it, that makes it make sense for our culture, is patriarchy. Study it, know it, critique it, cut it up and anatomize it any way you would like. The Discourse of Desire in its contemporary form, as it here and there subverts patriarchy, is a good deal younger than the oldest of my readers. The rhetoric of desire's discourse has only begun to sediment in the course of such personal and political intervention. Encourage it through your own discussions. Thank you. —Amherst 1993 NOTES 9. Samuel Taylor Coleridge, Selected Letters, ed. H. J. Jackson (New York: Oxford University Press, 1988). From the introduction by the editor: "The introduction of the postage stamp in 1840, six years after Coleridge's death, significantly altered the situation of correspondents. Until then, recipients paid postage; the writers themselves were responsible for making letters worth paying for. As objects paid for, letters had a certain status: they were shared with family and friends; in most households they were preserved and periodically reread; and on the death of the letter-writer, they were customarily returned to the family as part of the estate." 13. Laura Bohannan, "Shakespeare in the Bush," in *Ants, Indians, and Little Dinosaurs*, ed. Alan Teresi (New York: Scribner, c. 1975). (I would like to thank Margaret Minsky, who is responsible for my having my most recent copy of this delightful piece.) --- 2 Street Talk/Straight Talk 1. Discourse—an order of response, a mode of understanding, for which various rhetorical features may function as symptoms. Yet rhetoric is never wholly coextensive with discourse. Discourse and rhetoric control one another, yes—but precisely because of that control, neither is wholly at one with the other. Nevertheless—the relation of discourse to rhetoric is not the arbitrary relation, negotiable by introspection, of signified to signifier; it is the determined relation, negotiable by analysis, of the unconscious to the enunciated. 2. According to the discourse of "Discourse," rhetoric is quantifiable, particular, arrives in delimitable units, while meanings, to quote Quine (8), cannot be "individuated." Consider, then, four modes of rhetoric: *Street talk:* Brutal, repetitious, vulgar, it marks a subdiscourse of ignorance, rumor, misunderstanding, and outright superstition. It is fixed—now on the aggressive, now on the sexual, now on the cupidously acquisitive. The rhetoric of an underworld, its raison d'être is lying; in the pursuit of myriad dishonesties and selfishnesses, "getting over," as it most recently characterizes a major factor of its own enterprise. It arises in sexually high dimorphic idiocies: But whether we move in the realm of gossip or of braggadocio, whatever its topic, the very banality of its endlessly repeated circuits makes it the mark of the limited, the ilicit, a moment away from brute dumbness in one direction, a moment away from the linguistic zero of pure chatter in another. *Straight talk:* Indicating it with the rhetorical mark reserved for it by "street talk," it is mellifluous, precise, sophisticated: The subdiscourse it takes for itself is "the learned," the characterization of itself it employs in the acknowledgement of its own truth. It functions to mediate between truth and knowledge, and thus is saturated by both. It functions to resolve disorder, to clarify confusion, to calm and commingle the diverse
Configuration of Access Control Policy in REsource LOcation And Discovery (RELOAD) Base Protocol draft-ietf-p2psip-access-control-00 Abstract This document describes an extension to the REsource LOcation And Discovery (RELOAD) base protocol to distribute the code of new Access Control Policies without having to upgrade the RELOAD implementations in an overlay. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 20, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust’s Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 1. Introduction The RELOAD base protocol specifies an Access Control Policy as "defin[ing] whether a request from a given node to operate on a given value should succeed or fail." The paragraph continues saying that "[i]t is anticipated that only a small number of generic access control policies are required", but there is indications that this assumption will not hold. On all the RELOAD Usages defined in other documents than the RELOAD base protocol, roughly 50% defines a new Access Control Policy. The problem with a new Access Control Policy is that, because it is executed when a Store request is processed, it needs to be implemented by all the peers and so requires an upgrade of the software. This is something that is probably not possible in large overlays or on overlays using different implementations. For this reason, this document proposes an extension to the RELOAD configuration document that permits to transport the code of a new Access Control Policy to each peer. This extension defines a new element <code> that can be optionally added to a <configuration> element in the configuration document. The <code> element contains ECMAScript [ECMA-262] code that will be called for each StoredData object that use this access control policy. The code receives four parameters, corresponding to the Resource-ID, Signature, Kind and StoredDataValue of the value to store. The code returns true or false to signal to the implementation if the request should succeed or fail. For example the USER-MATCH Access Control Policy defined in the base protocol could be identically defined by inserting the following code in an <code> element: ```javascript return resource.equalsHash(signer.user_name.bytes()); ``` The <kind> parameters are also passed to the code, so the NODE-MULTIPLE Access Control Policy could be implemented like this: ```javascript for (var i = 0; i < kind.max_node_multiple; i++) { if (resource.equalsHash(signer.node_id, i.width(4))) { return true; } } return false; ``` 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] with the caveat that "SHOULD", "SHOULD NOT", "RECOMMENDED", and "NOT RECOMMENDED" are appropriate when valid exceptions to a general requirement are known to exist or appear to exist, and it is infeasible or impractical to enumerate all of them. However, they should not be interpreted as permitting implementors to fail to implement the general requirement when such failure would result in interoperability failure. 3. Processing A peer receiving a configuration document containing one or more <code> elements, either by retrieving it from the configuration server or in a ConfigUpdateReq message, MUST reject this configuration if it is not is not signed or if the signature verification fails. The Compact Relax NG Grammar for this element is: ```xml namespace acp = "urn:ietf:params:xml:ns:p2p:access-control" parameter & element acp:code { attribute name { xsd:string }, xsd:base64Binary }? ``` All peers in an overlay MUST implement this specification. One way to do this is to add a <mandatory-extension> element containing the "urn:ietf:params:xml:ns:p2p:access-control" namespace in the configuration document. The mandatory "name" attribute identifies the access control policy and can be used in the "name" attribute of a <kind> element as if it was defined by IANA. If the <code> element is present in the namespace allocated to this specification, and the Access Control Policy is not natively implemented, then the code inside the element MUST be called for each DataValue found in a received StoreReq for a Kind that is defined with this access control policy. The content of the <code> element MUST be decoded using the base64 [RFC4648] encoding, uncompressed using gzip [RFC1952] then converted to characters using UTF-8. <code> elements that are not encoded using UTF-8, compressed with gzip or finally converted to the base64 format MUST be ignored. For each call to the code, the following ECMAScript objects, properties and functions MUST be available: - `configuration.instance_name`: The name of the overlay, as a String object. - `configuration.topology_plugin`: The overlay algorithm, as a String object. - `configuration.node_id_length`: The length of a NodeId in bytes, as a Number object. configuration.kinds: An array of kinds (with the same definition than the kind object), indexed by id and eventually by name. configuration.evaluate(String, String, String): A function that evaluates the first parameter as an XPath expression against the configuration element, and returns the result as a String object. The second parameter contains a namespace prefix and the third parameter contains a namespace. kind.id: The id of the Kind associated with the entry, as a Number object. kind.name: If the Kind associated with the entry is registered by IANA, contains the name as a String object. If not, this property is undefined. kind.data_model: The name of the Data Model associated with the entry, as a String object. kind.access_control: The name of the Access Control Policy associated with the entry, as a String object. kind.max_count: The value of the max-count element in the configuration file, as a Number object. kind.max_size: The value of the max-size element in the configuration file as a Number object. kind.max_node_multiple: If the Access Control is MULTIPLE-NODE, contains the value of the max-node-multiple element in the configuration file, as a Number object. If not, this property is undefined. kind.evaluate(String, String, String): A function that evaluates the first parameter as an XPath expression against the kind element, and returns the result as a String object. The second parameter must contain a namespace prefix and the third parameter must contain a namespace. resource: An opaque object representing the Resource-ID, as an array of bytes. resource.entries: An array of arrays of entry objects, with the first array level indexed by Kind-Id and kind names, and the second level indexed by index, key or nothing, depending on the data model of the kind. This permits to retrieve all the values of all Kinds stored at the same Resource-ID than the entry currently processed. resource.equalsHash(Object...): A function that returns true if hashing the concatenation of the arguments according to the mapping function of the overlay algorithm is equal to the Resource-ID. Each argument is an array of bytes. entry.index: If the Data Model is ARRAY, contains the index of the entry, as a Number object. If not, this property is undefined. entry.key: If the Data Model is DICTIONARY, contains the key of the entry, as an array of bytes. If not, this property is undefined. entry.storage_time: The date and time used to store the entry, as a Date object. entry.lifetime: The validity for the entry in seconds, as a Number object. entry.exists: Indicates if the entry value exists, as Boolean object. entry.value: This property contains an opaque object that represents the whole data, as an array of bytes. entry.signer.user_name: The rfc822Name stored in the certificate that was used to sign the request, as a String object. entry.signer.node_id: The Node-ID stored in the certificate that was used to sign the request, as an array of bytes. The properties SHOULD NOT be modifiable or deletable and if they are, modifying or deleting them MUST NOT modify or delete the equivalent internal values (in other words, the code cannot be used to modify the elements that will be stored). The value returned by the code is evaluated to true or false, according to the ECMAScript rules. If the return value of one of the call to the code is evaluated to false, then the StoreReq fails, the state MUST be rolled back and an Error_Forbidden MUST be returned. 4. Security Considerations Because the configuration document containing the ECMAScript code is under the responsibility of the same entity that will sign it, using a scripting language does not introduce any additional risk if the RELOAD implementers follow the rules in this document (no side effect when modifying the parameters, only base classes of ECMAScript implemented, etc...). It is even possible to deal with less than perfect implementations as long as they do not accept a configuration file that is not signed correctly. One way for the signer to enforce this would be to deliberately send in a ConfigUpdate an incorrectly signed version of the configuration file and blacklist all the nodes that accepted it in a newly issued configuration file. By permitting multiple overlay implementations to interoperate inside one overlay, RELOAD helps build overlays that are not only resistant to hardware or communication failures, but also to programmer errors. Distributing the access control policy code inside the configuration document reintroduces this single point of failure. To mitigate this problem, new access control policies should be implemented natively as soon as possible, but if all implementations use the ECMAScript code as a blueprint for the native code, an hidden bug can be unwillingly duplicated. This is why developers should implement new access control policies from the normative text instead of looking at the code itself. To help developers do the right thing the code in the configuration document is obfuscated by compressing and encoding it as a base64 character string. 5. IANA Considerations This section requests IANA to register the following URN in the "XML Namespaces" class of the "IETF XML Registry" in accordance with [RFC3688]. URI: urn:ietf:params:xml:ns:p2p:access-control Registrant Contact: The IESG XML: This specification. 6. References 6.1. Normative References [I-D.ietf-p2psip-base] 6.2. Informative References Appendix A. Examples This section shows the ECMAScript code that could be used to implement the standard Access Control Policies defined in [I-D.ietf-p2psip-base]. A.1.1. USER-MATCH String.prototype['bytes'] = function () { var bytes = []; for (var i = 0; i < this.length; i++) { bytes[i] = this.charCodeAt(i); } return bytes; }; return resource.equalsHash(entry.signer.user_name.bytes()); A.1.2. NODE-MATCH return resource.equalsHash(entry.signer.node_id); A.1.3. USER-NODE-MATCH String.prototype['bytes'] = function () { var bytes = []; for (var i = 0; i < this.length; i++) { bytes[i] = this.charCodeAt(i); } return bytes; }; var equals = function (a, b) { if (a.length !== b.length) return false; for (var i = 0; i < a.length; i++) { if (a[i] !== b[i]) return false; } return true; }; return resource.equalsHash(entry.signer.user_name.bytes()) && equals(entry.key, entry.signer.node_id); A.1.4. NODE-MULTIPLE Number.prototype['width'] = function (w) { var bytes = []; for (var i = 0; i < w; i++) { bytes[i] = (this >>> ((w - i - 1) * 8)) & 255; } return bytes; }; for (var i = 0; i < kind.max_node_multiple; i++) { if (resource.equalsHash(entry.signer.node_id, i.width(4))) { return true; } } return false; A.2. Service Discovery Access Control Policy NODE-ID-MATCH [I-D.ietf-p2psip-service-discovery] defines a new Access Control Policy (NODE-ID-MATCH) that need to access the content of the entry to be written. If implemented as specified by this document, the ECMAScript code would look something like this: /* Insert here the code from http://jsfromhell.com/classes/bignumber */ var toBigNumber = function (node_id) { var bignum = new BigNumber(0); for (var i = 0; i < node_id.length; i++) { bignum = bignum.multiply(256).add(node_id[i]); } return bignum; }; var checkIntervals = function (node_id, level, node, factor) { var size = new BigNumber(2).pow(128); var node = toBigNumber(node_id); for (var f = 0; f < factor; f++) { var temp = size.multiply(new BigNumber(f).pow(new BigNumber(level).negate())); var min = temp.multiply(node.add(new BigNumber(f).divide(factor))); var max = temp.multiply(node.add(new BigNumber(f + 1).divide(factor))); if (node.compare(min) === -1 || node.compare(max) == 1 || node.compare(max) == 0) return false; } return true; }; var equals = function (a, b) { if (a.length !== b.length) return false; for (var i = 0; i < a.length; i++) { if (a[i] !== b[i]) return false; } } return true; }; var level = function (value) { var length = value[16] * 256 + value[17]; return value[18 + length] * 256 + value[18 + length + 1]; }; var node = function (value) { var length = value[16] * 256 + value[17]; return value[18 + length + 2] * 256 + value[18 + length + 3]; }; var namespace = function (value) { var length = value[16] * 256 + value[17]; return String.fromCharCode.apply(null, value.slice(18, length + 18)); }; var branching_factor = kind.evaluate('/branching-factor', 'redir', 'urn:ietf:params:xml:ns:p2p:redir'); return equals(entry.key, entry.signer.node_id) && (!entry.exists || checkIntervals(entry.key, level(entry.value), node(entry.value), branching_factor)) && (!entry.exists || resource.equalsHash(namespace(entry.value), level(entry.value), node(entry.value))); Note that the code for the BigNumber object was removed from this example, as the licensing terms are unclear. The code is available at [1]. A.3. VIPR Access Control Policy [I-D.petithuguenin-vipr-reload-usage] defines a new Access Control Policy. If implemented as specified by this document, the ECMAScript code would look something like this: ```javascript var equals = function (a, b) { if (a.length !== b.length) return false; for (var i = 0; i < a.length; i++) { if (a[i] !== b[i]) return false; } return true; ``` A.4. ShaRe Access Control Policy USER-CHAIN-ACL [I-D.ietf-p2psip-share] defines a new Access Control Policy, USER-CHAIN-ACL. If implemented as specified by this document, the ECMAScript code would look something like this: ```javascript var pattern = kind.evaluate('/share:pattern', 'share', 'urn:ietf:params:xml:ns:p2p:config-share'); var username = entry.signer.user_name.match(/^[^@]+@(.+)$/); var new_pattern = new RegExp(pattern.replace('$USER', username[1]).replace('$DOMAIN', username[2])); var length = entry.value[0] * 256 + entry.value[1]; var resource_name = String.fromCharCode.apply(null, entry.value.slice(2, length + 2)); return new_pattern.test(resource_name); ``` [[Note: the code is incomplete]] Appendix B. Release notes This section must be removed before publication as an RFC. B.1. Modifications between ietf-p2psip-reload-access-control and petithuguenin-p2psip-access-control-05 - Removed inconsistency in the terminology section. - Updated the IANA section and added reference to RFC 3688. - Removed "This is probably not legal..." in the security section. - Renamed "access-control-code" to simply "code" as it has to be prefixed by the namespace anyway, so there is no risk of conflict. B.2. Running Code Considerations - Reference Implementation and Access Control Policy script tester B.3. TODO List - Finish the code for ShaRe. - Update the reference implementation. Author’s Address Marc Petit-Huguenin Impedance Mismatch Email: petithug@acm.org Abstract This document defines a RELOAD Usage for managing shared write access to RELOAD Resources. Shared Resources in RELOAD (ShaRe) form a basic primitive for enabling various coordination and notification schemes among distributed peers. Access in ShaRe is controlled by a hierarchical trust delegation scheme maintained within an access list. A new USER-CHAIN-ACL access policy allows authorized peers to write a Shared Resource without owning its corresponding certificate. This specification also adds mechanisms to store Resources with a variable name which is useful whenever peer-independent rendezvous processes are required. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 28, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust’s Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction .............................................. 3 2. Terminology .............................................. 4 3. Shared Resources in RELOAD ................................. 5 3.1. Mechanisms for Isolating Stored Data .................. 6 4. Access Control List Definition ............................. 7 4.1. Overview ........................................... 7 4.2. Data Structure ..................................... 8 5. Extension for Variable Resource Names ..................... 10 5.1. Overview ........................................... 10 5.2. Data Structure ..................................... 10 5.3. Overlay Configuration Document Extension .............. 11 6. Access Control to Shared Resources ......................... 13 6.1. Granting Write Access ................................. 13 6.2. Revoking Write Access ................................ 14 6.3. Validating Write Access through an ACL ................ 14 6.4. Operations of Storing Peers .......................... 15 6.5. Operations of Accessing Peers ........................ 15 6.6. USER-CHAIN-ACL Access Policy ......................... 15 7. ACCESS-CONTROL-LIST Kind Definition ....................... 17 8. Security Considerations .................................... 18 8.1. Resource Exhaustion .................................. 18 8.2. Malicious or Misbehaving Storing Peer ................ 18 8.3. Privacy Issues ...................................... 18 9. IANA Considerations ....................................... 19 9.1. Access Control Policy ................................ 19 9.2. Data Kind-ID ....................................... 19 10. Acknowledgments .......................................... 20 11. References .............................................. 21 11.1. Normative References ................................ 21 11.2. Informative References ............................... 21 Appendix A. Change Log ........................................ 22 Authors’ Addresses ........................................... 24 1. Introduction This document defines a RELOAD Usage for managing shared write access to RELOAD Resources and a mechanism to store Resources with a variable name. The Usage for Shared Resources in RELOAD (ShaRe) enables overlay users to share their exclusive write access to specific Resource/Kind pairs with others. Shared Resources form a basic primitive for enabling various coordination and notification schemes among distributed peers. Write permission is controlled by an Access Control List (ACL) Kind that maintains a chain of Authorized Peers for a particular Shared Resource. A newly defined USER-CHAIN-ACL access control policy enables shared write access in RELOAD. The Usage for Shared Resources in RELOAD is designed for jointly coordinated group applications among distributed peers (e.g., third party registration, see [I-D.ietf-p2psip-sip], or distributed conferencing, see [I-D.ietf-p2psip-disco]). Of particular interest are rendezvous processes, where a single identifier is linked to multiple, dynamic instances of a distributed cooperative service. Shared write access is based on a trust delegation mechanism. It transfers the authorization to write a specific Kind data by storing logical Access Control Lists. An ACL contains the ID of the Kind to be shared and contains trust delegations from one authorized to another (previously unauthorized) user. Shared write access augments the RELOAD security model, which is based on the restriction that peers are only allowed to write resources at a small set of well defined locations (Resource-IDs) in the overlay. Using the standard access control rules in RELOAD, these locations are bound to the username or Node-ID in the peer’s certificate. This document extends the base policies to enable a controlled write access for multiple users to a common Resource ID. Additionally, this specification defines an optional mechanism to store Resources with a variable Resource Name. It enables the storage of Resources whose name complies to a specific pattern. Definition of the pattern is arbitrary, but must contain the username of the Resource creator. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. This document uses the terminology and definitions from the RELOAD base [I-D.ietf-p2psip-base] and the peer-to-peer SIP concepts draft [I-D.ietf-p2psip-concepts]. Additionally, the following terms are used: Shared Resource: The term Shared Resource in this document defines a RELOAD Resource with its associated Kinds, that can be written or overwritten by multiple RELOAD users following the specifications in this document. Access Control List: The term Access Control List in this document defines a logical list of RELOAD users allowed to write a specific RELOAD Resource/Kind pair by following the specifications in this document. The list items are stored as Access Control List Kinds that map trust delegations from user A to user B, where A is allowed to write a Shared Resource and the Access Control List, while B is a user that obtains write access to specified Kinds from A. Resource Owner: The term Resource Owner in this document defines a RELOAD peer that initially stored a Resource to be shared. The Resource Owner possesses the RELOAD certificate that grants write access to a specific Resource/Kind pair using the RELOAD certificate-based access control policies. Authorized Peer: The term Authorized Peer in this document defines a RELOAD peer that was granted write access to a Shared Resource by permission of the Resource Owner or another Authorized Peer. 3. Shared Resources in RELOAD A RELOAD user that owns a certificate for writing at a specific overlay location can maintain one or more RELOAD Kinds that are designated for a non-exclusive write access shared with other RELOAD users. The mechanism to share those Resource/Kind pairs with a group of users consists of two basic steps. 1. Storage of the Resource/Kind pairs to be shared. 2. Storage of an Access Control List (ACL) associated with those Kinds. ACLs are created by the Resource Owner and contain ACL items, each delegating the permission of writing the shared Kind to a specific user called Authorized Peer. For each shared Kind data, its Resource owner stores a root item that initiates an Access Control List. Trust delegation to the Authorized Peer can include the right to further delegate the write permission, enabling a tree of trust delegations with the Resource Owner as trust anchor at its root. The Resource/Kind pair to be shared can be any RELOAD Kind that complies to the following specifications: Isolated Data Storage: To prevent concurrent writing from race conditions, each data item stored within a Shared Resource SHALL be exclusively maintained by the RELOAD user who created it. Hence, Usages that allow the storage of Shared Resources are REQUIRED to use either the array or dictionary data model and apply additional mechanisms for isolating data as described in Section 3.1. Access Control Policy: To ensure write access to Shared Resource by Authorized Peers, each Usage MUST use the USER-CHAIN-ACL access policy as described in Section 6.6. Resource Name Extension: To enable Shared Resources to be stored using a variable resource name, this document defines an optional ResourceNameExtension structure. It contains the Resource Name of the Kind data to be stored and allows any receiver of a shared data to validate whether the Resource Name hashes to the Resource-ID. The ResourceNameExtension is made optional by configuration. The ResourceNameExtension field is only present in the Kind data structure when configured in the corresponding kind-block of the overlay configuration document (for more details see Section 5.3). If the configuration allows variable resource names, a Kind using the USER-CHAIN-ACL policy MUST use the ResourceNameExtension as initial field within the Kind data. structure definition. Otherwise the Kind data structure does not contain the ResourceNameExtension structure. 3.1. Mechanisms for Isolating Stored Data This section defines mechanisms to avoid race conditions while concurrently writing an array or dictionary of a Shared Resource. If a dictionary is used in the Shared Resource, the dictionary key MUST be the Node-ID of the certificate that will be used to sign the stored data. Thus data access is bound to the unique ID-holder. If the data model of the Shared Resource is an array, each Authorized Peer SHALL obtain its exclusive range of the array indices. The following algorithm will generate an array indexing scheme that avoids collisions. 1. Obtain the Node-ID of the certificate that will be used to sign the stored data 2. Take the least significant 24 bits of that Node-ID 3. Concatenate an 8 bit long short individual index value to those 24 bit of the Node-ID The resulting 32 bits long integer MUST be used as the index for storing an array entry in a Shared Resource. The 8 bit individual index can be incremented individually for further array entries and allows for 256 distinct entries per Peer. The mechanism to create the array index is related to the pseudo-random algorithm to generate an SSRC identifier in RTP, see Section 8.1 in [RFC3550] for calculating the probability of a collision. 4. Access Control List Definition 4.1. Overview An Access Control List (ACL) is a (self-managed) shared resource that contains a list of AccessControlListItem structures as defined in Section 4.2. Each entry delegates write access for a specific Kind data to a single RELOAD user. An ACL enables the RELOAD user who is authorized to write a specific Resource-ID to delegate his exclusive write access to a specific Kind to further users of the same RELOAD overlay. Each Access Control List data structure therefore carries the information about who obtains write access, the Kind-ID of the Resource to be shared, and whether delegation includes write access to the ACL itself. The latter condition grants the right to delegate write access further for the Authorized Peer. Access Control Lists are stored at the same overlay location as the Shared Resource and use the RELOAD array data model. They are initially created by the Resource Owner. Figure 1 shows an example of an Access Control List. We omit the res_name_ext field to simplify illustration. The array entry at index 0x123abc001 displays the initial creation of an ACL for a Shared Resource of Kind-ID 1234 at the same Resource-ID. It represents the root item of the trust delegation tree for this shared RELOAD Kind. The root entry MUST contain the username of the Resource owner in the "to_user" field and can only be written by the owner of the public key certificate associated with this Resource-ID. The allow_delegation (ad) flag for a root ACL item is set to 1 by default. The array index is generated by using the mechanism for isolating stored data as described in Section 3.1. Hence, the most significant 24 bits of the array index (0x123abc) are the least significant 24 bits of the Node-ID of the Resource Owner. The array item at index 0x123abc002 represents the first trust delegation to an Authorized Peer that is thus permitted to write to the Shared Resource of Kind-ID 1234. Additionally, the Authorized peer Alice is also granted (limited) write access to the ACL as indicated by the allow_delegation flag (ad) set to 1. This configuration authorizes Alice to store further trust delegations to the Shared Resource, i.e., add items to the ACL. On the contrary, index 0x456def001 illustrates trust delegation for Kind-ID 1234, in which the Authorized Peer Bob is not allowed to grant access to further peers (ad = 0). Each Authorized Peer signs its ACL items by using its own signer identity along with its own private key. This allows other peers to validate the origin of an ACL item and makes ownership transparent. To manage Shared Resource access of multiple Kinds at a single location, the Resource Owner can create new ACL entries that refer to another Kind-ID as shown in array entry index 0x123abc003. Note that overwriting existing items in an Access Control List that reference a different Kind-ID revokes all trust delegations in the corresponding subtree (see Section 6.2). Authorized Peers are only enabled to overwrite existing ACL item they own. The Resource Owner is allowed to overwrite any existing ACL item, but should be aware of its consequences. <table> <thead> <tr> <th>#Index</th> <th>Array Entries</th> <th>signed by</th> </tr> </thead> <tbody> <tr> <td>123abc001</td> <td>to_user:Owner Kind:1234 ad:1</td> <td>Owner</td> </tr> <tr> <td>123abc002</td> <td>to_user:Alice Kind:1234 ad:1</td> <td>Owner</td> </tr> <tr> <td>123abc003</td> <td>to_user:Owner Kind:4321 ad:1</td> <td>Owner</td> </tr> <tr> <td>123abc004</td> <td>to_user:Carol Kind:4321 ad:0</td> <td>Owner</td> </tr> <tr> <td>...</td> <td>...</td> <td>...</td> </tr> <tr> <td>456def001</td> <td>to_user:Bob Kind:1234 ad:0</td> <td>Alice</td> </tr> <tr> <td>...</td> <td>...</td> <td>...</td> </tr> </tbody> </table> Figure 1: Simplified example of an Access Control including entries for two different Kind-IDs and varying delegation (ad) configurations Implementations of ShaRe should be aware that the trust delegation in an Access Control List need not be loop free. Self-contained circular trust delegation from A to B and B to A are syntactically possible, even though not very meaningful. 4.2. Data Structure The Kind data structure for the Access Control List is defined as follows: ```c struct { /* res_name_ext is optional, see documentation */ ResourceNameExtension res_name_ext; opaque to_user<0..2^16-1>; KindId kind; }; ``` The AccessControlListItem structure is composed of: - **res_name_ext**: This optional field contains the Resource Name of a ResourceNameExtension (see Section 5.2) to be used by a Shared Resource with variable resource name. This name serves the storing peer for validating, whether a variable resources name matches one of the predefined naming pattern from the configuration document for this Kind. The presence of this field is bound to a variable resource name element in the corresponding kind-block of the configuration document whose "enable" attribute is set to true (see Section 5.3). Otherwise, if the "enable" attribute is false, the res_name_ext field SHALL NOT be present in the Kind data structure. - **to_user**: This field contains the username of the RELOAD peer that obtains write permission to the Shared Resource. - **kind**: This field contains the Kind-ID of the Shared Resource. - **allow_delegation**: If true, this Boolean flag indicates that the Authorized Peer in the ‘to_user’ field is allowed to add additional entries to the ACL for the specified Kind-ID. 5. Extension for Variable Resource Names 5.1. Overview In certain use cases such as conferencing (c.f., [I-D.ietf-p2psip-disco]) it is desirable to increase the flexibility of a peer in using Resource Names beyond those defined by the username or Node-ID fields in its certificate. For this purpose, this document presents the concept for variable Resources Names that enables providers of RELOAD instances to define relaxed naming schemes for overlay Resources. Each RELOAD node uses a certificate to identify itself using its user name (or Node-ID) while storing data under a specific Resource-ID. The specifications in this document scheme adhere to this paradigm, but enable a RELOAD peer to store values of Resource Names that are derived from the username in its certificate. This is done by using a Resource Name with a variable substring that still matches the user name in the certificate using a pattern defined in the overlay configuration document. Thus despite being variable, an allowable Resource Name remains tied to the Owner’s certificate. A sample pattern might be formed as follows. Example Pattern: ``` .*-conf-\$USER@\$DOMAIN ``` When defining the pattern, care must be taken to avoid conflicts arising from two usernames of which one is a substring of the other. In such cases, the holder of the shorter name could threaten to block the resources of the longer-named peer by choosing the variable part of a Resource Name to contain the entire longer username. This problem can easily be mitigated by delimiting the variable part of the pattern from the username part by some fixed string, that by convention is not part of a username (e.g., the "-conf-" in the above Example). 5.2. Data Structure This section defines the optional ResourceNameExtension structure for every Kind that uses the USER-CHAIN-ACL access control policy. enum { pattern (1), (255)} ResourceNameType; struct { ResourceNameType type; uint16 length; select(type) { case pattern: opaque resource_name<0..2^16-1>; } } } The content of the ResourceNameExtension consist of length: This field contains the length of the remaining data structure. It is only used to allow for further extensions to this data structure. The content of the rest of the data structure depends of the ResourceNameType. Currently, the only defined type is "pattern". If the type is "pattern", then the following data structure contains an opaque <0..2^16-1> field containing the Resource Name of the Kind being stored. The type "pattern" further indicates that the Resource Name MUST match to one of the variable resource name pattern defined for this Kind in the configuration document. The ResourceNameType enum and the ResourceNameExtension structure can be extended by further Usages to define other naming schemes. 5.3. Overlay Configuration Document Extension This section extends the overlay configuration document by defining new elements for patterns relating resource names to user names. Configurations in this overlay document MUST adhere in syntax and semantic of names as defined by the context of use. For example, AOR syntax restrictions apply when using P2PSIP[I-D.ietf-p2psip-sip], while a more general naming is feasible in plain RELOAD. The <variable-resource-names> element serves as a container for one or multiple <pattern> sub-elements. It is an additional parameter within the kind block and has a boolean "enable" attribute that indicates, if true, that the overlay provider allows variable resource names for this Kind. The default value of the "enable" attribute is "false". In the absence of a <variable-resource-names> Section 6.6), implementors SHOULD assume this default value. A <pattern> element MUST be present if the "enabled" attribute of its parent element is set to true. Each <pattern> element defines a pattern for constructing extended resource names for a single Kind. It is of type xsd:string and interpreted as a regular expression according to "POSIX Extended Regular Expression" (see the specifications in [IEEE-Posix]). In this regular expression, $USER and $DOMAIN are used as variables for the corresponding parts of the string in the certificate user name field (with $USER preceding and $DOMAIN succeeding the '@'). Both variables MUST be present in any given pattern definition. If no pattern is defined for a Kind or the "enabled" attribute is false, allowable Resource Names are restricted to the username of the signer for Shared Resource. The Relax NG Grammar for the Variable Resource Names Extension reads: ```xml <!-- VARIABLE RESOURCE URN SUB-NAMESPACE --> <!-- VARIABLE RESOURCE NAMES ELEMENT --> kind-parameter & element share:variable-resource-names { attribute enable { xsd:boolean } <!-- PATTERN ELEMENT --> element pattern { xsd:string }* } ``` 6. Access Control to Shared Resources 6.1. Granting Write Access Write access to a Kind that is intended to be shared with other RELOAD users can solely be issued by the Resource Owner. A Resource Owner can share RELOAD Kinds by using the following procedure. - The Resource Owner stores an ACL root item at the Resource-ID of the Shared Resource. The root item contains the resource name extension field (see Section 5.2), the username of the Resource Owner and Kind-ID of the Shared Resource. The allow_delegation flag is set to 1. The index of array data structure MUST be generated as described in Section 3.1. - Further ACL items for this Kind-ID stored by the Resource Owner will delegate write access to Authorized Peers. These ACL items contain the same resource name extension field, the username of the Authorized Peer and the Kind-ID of the Shared Resource. Optionally, the Resource Owner sets the "ad" to 1 (the default equals 0) to enable the Authorized Peer to further delegate write access. Each succeeding ACL item created by the Resource Owner can be stored in the numerical order of the array index starting with the index of the root item incremented by one. An Authorized Peer with delegation allowance ("ad"=1) can extend the access to an existing Shared Resource as follows. - An Authorized Peer can store additional ACL items at the Resource-ID of the Shared Resource. These ACL items contain the resource name extension field, the username of the newly Authorized Peer, and the Kind-ID of the Shared Resource. Optionally, the "ad" flag is set to 1 for allowing the Authorized Peer to further delegate write access. The array index MUST be generated as described in Section 3.1. Each succeeding ACL item can be stored in the numerical order of the array index. A store request by an Authorized Peer that attempts to overwrite any ACL item signed by another Peer is unauthorized and causes an Error_Forbidden response from the Storing Peer. Such access conflicts could be caused by an array index collision. However, the probability of a collision of two or more identical array indices will be negligibly low using the mechanism for isolating stored data (see Section 3.1). 6.2. Revoking Write Access Write permissions are revoked by storing a non-existent value [I-D.ietf-p2psip-base] at the corresponding item of the Access Control List. Revoking a permission automatically invalidates all delegations performed by that user including all subsequent deviations. This allows to invalidate entire subtrees of the delegations tree with only a single operation. Overwriting the root item with a non-existent value of an Access List invalidates the entire delegations tree. An existing ACL item MUST only be overwritten by the user who initially stored the corresponding entry, or by the Resource Owner that is allowed to overwrite all ACL items for revoking write access. 6.3. Validating Write Access through an ACL Access Control Lists are used to transparently validate authorization of peers for writing a data value at a Shared Resource. Thereby it is assumed that the validating peer is in possession of the complete and most recent ACL for a specific Resource/Kind pair. The corresponding procedure consists of recursively traversing the trust delegation tree and proceeds as follows. 1. Obtain the username of the certificate used for signing the data stored at the Shared Resource. 2. Validate that an item of the corresponding ACL (i.e., for this Resource/Kind pair) contains a "to_user" field whose value equals the username obtained in step 1. If the Shared Resource under examination is an Access Control List Kind, further validate if the "ad" flag is set to 1. 3. Select the username of the certificate that was used to sign the ACL item obtained in step 2. 4. Validate that an item of the corresponding ACL contains a "to_user" field whose value equals the username obtained in step 3. Additionally validate that the "ad" flag is set to 1. 5. Repeat steps 3 and 4 until the "to_user" value is equal to the username of the signer of the previously selected ACL item. This final ACL item is expected to be the root item of this ACL which SHALL be further validated by verifying that the root item was signed by the owner of the ACL Resource. The trust delegation chain is valid if and only if all verification steps succeed. In this case, the creator of the data value of the Shared Resource is an Authorized Peer. Note that the ACL validation procedure can be omitted whenever the creator of data at a Shared Resource is the Resource Owner itself. The latter can be verified by its public key certificate as defined in Section 6.6. 6.4. Operations of Storing Peers Storing peers at which Shared Resource and ACL are physically stored, are responsible for controlling storage attempts to a Shared Resource and its corresponding Access Control List. To assert the USER-CHAIN-ACL access policy (see Section 6.6), a storing peer MUST perform the access validation procedure described in Section 6.3 on any incoming store request using the most recent Access Control List for every Kind that uses the USER-CHAIN-ACL policy. It SHALL further ensure that only the Resource Owner stores new ACL root items for Shared Resources. 6.5. Operations of Accessing Peers Accessing peers, i.e., peers that fetch a Shared Resource, MAY validate that the originator of a Shared Resource was authorized to store data at this Resource-ID by processing the corresponding ACL. To enable an accessing peer to perform the access validation procedure described in Section 6.3, it first needs to obtain the most recent Access Control List in the following way. 1. Send a Stat request to the Resource-ID of the Shared Resource to obtain all array indexes of stored ACL Kinds. 2. Fetch all indexes of existing ACL items at this Resource-ID by using the array ranges retrieved in the Stat request answer. Peers can cache previously fetched Access Control Lists up to the maximum lifetime of an individual item. Since stored values could have been modified or invalidated prior to their expiration, an accessing peer SHOULD use a Stat request to check for updates prior to using the data cache. 6.6. USER-CHAIN-ACL Access Policy This document specifies an additional access control policy to the RELOAD base draft [I-D.ietf-p2psip-base]. The USER-CHAIN-ACL policy allows Authorized Peers to write a Shared Resource, even though they do not own the corresponding certificate. Additionally, the USER-CHAIN-ACL allows the storage of Kinds with a variable resource name that are following one of the specified naming pattern. Hence, on an inbound store request on a Kind that uses the USER-CHAIN-ACL access policy, the following rules MUST be applied: In the USER-CHAIN-ACL policy, a given value MUST be written or overwritten, if either one of USER-MATCH or USER-NODE-MATCH (mandatory if the data model is dictionary) access policies of the base document [I-D.ietf-p2psip-base] applies. Otherwise, the value MUST be written if the certificate of the signer contains a username that matches to one of the variable resource name pattern (c.f. Section 5) specified in the configuration document and, additionally, the hashed Resource Name matches the Resource-ID. The Resource Name of the Kind to be stored MUST be taken from the mandatory ResourceNameExtension field in the corresponding Kind data structure. Otherwise, the value MUST be written if the ACL validation procedure described in Section 6.3 has been successfully applied. 7. ACCESS-CONTROL-LIST Kind Definition This section defines the ACCESS-CONTROL-LIST Kind previously described in this document. Name: ACCESS-CONTROL-LIST Kind IDs: The Resource Name for ACCESS-CONTROL-LIST Kind-ID is the Resource Name of the Kind that will be shared by using the ACCESS-CONTROL-LIST Kind. Data Model: The data model for the ACCESS-CONTROL-LIST Kind-ID is array. The array indexes are formed by using the mechanism for isolated stored data as described in Section 3.1 Access Control: USER-CHAIN-ACL (see Section 6.6) 8. Security Considerations In this section we discuss security issues that are relevant to the usage of shared resources in RELOAD. 8.1. Resource Exhaustion Joining a RELOAD overlay inherently poses a certain resource load on a peer, because it has to store and forward data for other peers. In common RELOAD semantics, each Resource ID and thus position in the overlay may only be written by a limited set of peers - often even only a single peer, which limits this burden. In the case of Shared Resources, a single resource may be written by multiple peers, who may even write an arbitrary number of entries (e.g., delegations in the ACL). This leads to an enhanced use of resources at individual overlay nodes. The problem of resource exhaustion can easily be mitigated for Usages based on the ShaRe-Usage by imposing restrictions on size, i.e., `<max-size>` element for a certain Kind in the configuration document. 8.2. Malicious or Misbehaving Storing Peer The RELOAD overlay is designed to operate despite the presence of a small set of misbehaving peers. This is not different for Shared Resources since a small set of malicious peers does not disrupt the functionality of the overlay in general, but may have implications for the peers needing to store or access information at the specific locations in the ID space controlled by a malicious peer. A storing peer could withhold stored data which results in a denial of service to the group using the specific resource. But it could not return forged data, since the validity of any stored data can be independently verified using the attached signatures. 8.3. Privacy Issues All data stored in the Shared Resource is publicly readable, thus applications requiring privacy need to encrypt the data. The ACL needs to be stored unencrypted, thus the list members of a group using a Shared Resource will always be publicly visible. 9. IANA Considerations 9.1. Access Control Policy IANA shall register the following entry in the "RELOAD Access Control Policies" Registry (cf., [I-D.ietf-p2psip-base]) to represent the USER-CHAIN-ACL Access Control Policy, as described in Section 6.6. [NOTE TO IANA/RFC-EDITOR: Please replace RFC-AAAA with the RFC number for this specification in the following list.] +-------------------+----------+ | Kind | RFC | +-------------------+----------+ | USER-CHAIN-ACL | RFC-AAAA | 9.2. Data Kind-ID IANA shall register the following code point in the "RELOAD Data Kind-ID" Registry (cf., [I-D.ietf-p2psip-base]) to represent the ShaRe ACCESS-CONTROL-LIST kind, as described in Section 7. [NOTE TO IANA/RFC-EDITOR: Please replace RFC-AAAA with the RFC number for this specification in the following list.] +-----------------------+------------+----------+ | Kind | Kind-ID | RFC | +-----------------------+------------+----------+ | ACCESS-CONTROL-LIST | 17 | RFC-AAAA | 10. Acknowledgments This work was stimulated by fruitful discussions in the P2PSIP working group and SAM research group. We would like to thank all active members for constructive thoughts and feedback. In particular, the authors would like to thank (in alphabetical order) Lothar Grimm, Cullen Jennings, Peter Musgrave, Joerg Ott, Marc Petit-Huguenin, Peter Pogrzeba, and Jan Seedorf. This work was partly funded by the German Federal Ministry of Education and Research, projects HAMcast, Mindstone, and SAFEST. 11. References 11.1. Normative References [I-D.ietf-p2psip-base] [IEEE-Posix] 11.2. Informative References [I-D.ietf-p2psip-concepts] [I-D.ietf-p2psip-disco] [I-D.ietf-p2psip-sip] Appendix A. Change Log The following changes have been made from version draft-ietf-p2psio-share-00: 1. Clarified use of identities in ACLs 2. Specified use of Posix regular expressions in configuration document 3. Added IANA considerations 4. Editorial improvements 5. Updated References The following changes have been made from version draft-knauf-p2psip-share-02: 1. Editorial improvements 2. Updated References The following changes have been made from version draft-knauf-p2psip-share-01: 1. Simplified the ACL data structure in response to WG feedback 2. Added ResourceNameExtension data structure to simplify the use of variable resource names 3. Restructured document 4. Many editorial improvements The following changes have been made from version draft-knauf-p2psip-share-00: 1. Integrated the USER-PATTERN-MATCH access policy into USER-CHAIN-ACL 2. Access Control List Kind uses USER-CHAIN-ACL exclusively 3. Resources to be shared use USER-CHAIN-ACL exclusively 4. More precise specification of mandatory User_name and Resource_name fields for Shared Resources 5. Added mechanism for isolating stored data to prevent race conditions while concurrent storing 6. XML Extension for variable resource names uses its own namespace 7. Many editorial improvements Authors’ Addresses Alexander Knauf HAW Hamburg Berliner Tor 7 Hamburg D-20099 Germany Phone: +4940428758067 Email: alexanderknauf@gmail.com URI: Thomas C. Schmidt HAW Hamburg Berliner Tor 7 Hamburg D-20099 Germany Email: schmidt@informatik.haw-hamburg.de URI: http://inet.cpt.haw-hamburg.de/members/schmidt Gabriel Hege daviko GmbH Am Borsigturm 50 Berlin D-13507 Germany Phone: +493043004344 Email: hege@daviko.com URI: Matthias Waehlisch link-lab & FU Berlin Hoenower Str. 35 Berlin D-10318 Germany Email: mw@link-lab.net URI: http://www.inf.fu-berlin.de/~waehl A SIP Usage for RELOAD draft-ietf-p2psip-sip-09 Abstract This document defines a SIP Usage for REsource LOcation And Discovery (RELOAD). The SIP Usage provides the functionality of a SIP proxy or registrar in a fully-distributed system and includes a lookup service for Address of Records (AORs) stored in the overlay. It also defines Globally Routable User Agent Uris (GRUUs) that allow the registrations to map an AOR to a specific node reachable through the overlay. After such initial contact of a peer, the AppAttach method is used to establish a direct connection between nodes through which SIP messages are exchanged. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 29, 2013. Copyright Notice Table of Contents 1. Introduction .............................................. 4 2. Terminology .............................................. 6 3. Registering AORs in the Overlay .......................... 6 3.1. Overview ........................................... 6 3.2. Data Structure ...................................... 7 3.3. Access Control ..................................... 9 3.4. Overlay Configuration Document Extension .......... 9 4. Looking up an AOR ......................................... 11 4.1. Finding a Route to an AOR ......................... 11 4.2. Resolving an AOR ................................... 11 5. Forming a Direct Connection .............................. 11 6. Using GRUUs .............................................. 12 7. SIP-Registration Kind Definition ....................... 13 8. Security Considerations ................................ 13 8.1. RELOAD-Specific Issues ......................... 13 8.2. SIP-Specific Issues ............................... 14 8.2.1. Fork Explosion ................................ 14 8.2.2. Malicious Retargeting ........................ 14 8.2.3. Misuse of AORs ................................ 14 8.2.4. Privacy Issues ................................ 14 9. IANA Considerations ..................................... 14 9.1. Data Kind-ID ...................................... 15 9.2. XML Name Space Registration ...................... 15 10. Acknowledgments ......................................... 15 11. References .............................................. 15 11.1. Normative References ............................. 15 11.2. Informative References ........................... 16 Appendix A. Third Party Registration ...................... 17 Appendix B. Change Log ..................................... 17 B.1. Changes since draft-ietf-p2psip-sip-08 .......... 17 B.2. Changes since draft-ietf-p2psip-sip-07 .......... 17 B.3. Changes since draft-ietf-p2psip-sip-06 .......... 17 Authors’ Addresses ........................................ 18 1. Introduction The REsource LOcation And Discovery (RELOAD) [I-D.ietf-p2psip-base] specifies a peer-to-peer (P2P) signaling protocol for the general use on the Internet. This document defines a SIP Usage of RELOAD that allows SIP [RFC3261] user agents (UAs) to establish peer-to-peer SIP (or SIPS) sessions without the requirement for permanent proxy or registration servers, e.g., a fully distributed telephony service. In such a network, the RELOAD overlay itself performs the registration and rendezvous functions ordinarily associated with such servers. The SIP Usage involves two basic functions. Registration: SIP UAs can use the RELOAD data storage functionality to store a mapping from their address-of-record (AOR) to their Node-ID in the overlay, and to retrieve the Node-ID of other UAs. Rendezvous: Once a SIP UA has identified the Node-ID for an AOR it wishes to call, it can use the RELOAD message routing system to set up a direct connection for exchanging SIP messages. Mappings are stored in the SipRegistration Resource Record defined in this document. All operations required to perform a SIP registration or rendezvous are standard RELOAD protocol methods. For example, Bob registers his AOR, "bob@dht.example.com", for his Node-ID "1234". When Alice wants to call Bob, she queries the overlay for "bob@dht.example.com" and receives Node-ID 1234 in return. She then uses the overlay routing to establish a direct connection with Bob and can directly transmit a standard SIP INVITE. In detail, this works along the following steps. 1. Bob, operating Node-ID 1234, stores a mapping from his AOR to his Node-ID in the overlay by applying a Store request for "bob@dht.example.com -> 1234". 2. Alice, operating Node-ID 5678, decides to call Bob. She retrieves Node-ID "1234" by performing a Fetch request on "bob@dht.example.com". 3. Alice uses the overlay to route an AppAttach message to Bob’s peer (ID 1234). Bob responds with his own AppAttach and they set up a direct connection, as shown in Figure 1. Note that mutual ICE checks are invoked automatically from AppAttach message exchange. Figure 1: Connection setup in P2P SIP using the RELOAD overlay It is important to note that here the only role of RELOAD is to set up the direct SIP connection between Alice and Bob. As soon as the ICE checks complete and the connection is established, ordinary SIP or SIPS is used. In particular, the establishment of the media channel for a phone call happens via the usual SIP mechanisms, and RELOAD is not involved. Media never traverses the overlay. After the successful exchange of SIP messages, call peers run ICE connectivity checks for media. In addition to mappings from AORs to Node-IDs, the SIP Usage also allows mappings from AORs to other AORs. This enables an indirection useful for call forwarding. For instance, if Bob wants his phone calls temporarily forwarded to Charlie, he can store the mapping "bob@dht.example.com -> charlie@dht.example.com". When Alice wants to call Bob, she retrieves this mapping and can then fetch Charlie’s AOR to retrieve his Node-ID. These mechanisms are described in Section 3. Alternatively, Globally Routable User Agent URIs (GRUUs) can be used for directly accessing peers. They are handled via a separate mechanism, as described in Section 6. The SIP Usage for RELOAD addresses a fully distributed deployment of session-based services among overlay peers. Two opposite scenarios of deploying P2P SIP services are in the focus of this document: A highly regulated environment of a "single provider" that admits parties using AORs with domains from controlled namespace(s), only, and an open, multi-party infrastructure that liberally allows a registration and rendezvous for various or any domain namespace. It is noteworthy in this context that - in contrast to regular SIP - domain names play no role in routing to a proxy server. Once connectivity to an overlay is given, any name registration can be technically processed. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. We use the terminology and definitions from Concepts and Terminology for Peer to Peer SIP [I-D.ietf-p2psip-concepts] and the RELOAD Base Protocol [I-D.ietf-p2psip-base] extensively in this document. In addition, term definitions from SIP [RFC3261] apply to this memo. The term AOR is the SIP "Address of Record" used to identify a user in SIP. For example, alice@example.com could be the AOR for Alice. For the purposes of this specification, an AOR is considered not to include the scheme (e.g sip:) as the AOR needs to match the rfc822Name in the X509v3 certificates. It is worth noting that SIP and SIPS are distinguished in P2PSIP by the Application-ID. 3. Registering AORs in the Overlay 3.1. Overview In ordinary SIP, a UA registers its AOR and location with a registrar. In RELOAD, this registrar function is provided by the overlay as a whole. To register its location, a RELOAD peer stores a SipRegistration Resource Record under its own AOR using the SIP-REGISTRATION Kind, which is formally defined in Section 7. A RELOAD overlay MAY restrict the storage of AORs. Namespaces (i.e., the right hand side of the AOR) that are supported for registration and lookup can be configured for each RELOAD deployment as described in Section 3.4. As a simple example, consider Alice with AOR "alice@dht.example.org" at Node-ID "1234". She might store the mapping "alice@dht.example.org -> 1234" telling anyone who wants to call her to contact node "1234". RELOAD peers MAY store two kinds of SIP mappings, - from an AOR to a destination list (a single Node-ID is just a trivial destination list), or - from an AOR to another AOR. The meaning of the first kind of mapping is "in order to contact me, form a connection with this peer." The meaning of the second kind of mapping is "in order to contact me, dereference this AOR". The latter allows for forwarding. For instance, if Alice wants her calls to be forwarded to her secretary, Sam, she might insert the following mapping "alice@dht.example.org -> sam@dht.example.org". 3.2. Data Structure This section defines the SipRegistration Resource Record as follows: ```c enum { sip_registration_uri(1), sip_registration_route(2), (255) } SipRegistrationType; select (SipRegistration.type) { case sip_registration_uri: opaque uri<0..2^16-1>; case sip_registration_route: opaque contact_prefs<0..2^16-1>; Destination destination_list<0..2^16-1>; /* This type can be extended */ } SipRegistrationData; ``` ```c struct { SipRegistrationType type; uint16 length; SipRegistrationData data; } SipRegistration; ``` The contents of the SipRegistration Resource Record are: type the type of the registration length the length of the rest of the PDU data the registration data o If the registration is of type "sip_registration_uri", then the contents are an opaque string containing the URI. o If the registration is of type "sip_registration_route", then the contents are an opaque string containing the callee’s contact preferences and a destination list for the peer. The encoding of contact_prefs - the callee’s contact preferences - follows the media feature set syntax of [RFC2533] (see also [RFC2738]). As an example, a voicemail server that is a UA that supports audio and video media types and is not mobile would carry the following feature set description in its contact_prefs attribute: (& (sip.audio=TRUE) (sip.video=TRUE) (sip.actor=msg-taker) (sip.automata=TRUE) (sip.mobility=fixed) (sip.methods=INVITE) (sip.methods=BYE) (sip.methods=OPTIONS) (sip.methods=ACK) (sip.methods=CANCEL)) A callee MAY indicate that it prefers contact via a particular SIP scheme - SIP or SIPS - by using one of the following contact_prefs attribute: (sip.schemes=SIP) (sip.schemes=SIPS) RELOAD explicitly supports multiple registrations for a single AOR. The registrations are stored in a Dictionary with Node-IDs as the dictionary keys. Consider, for instance, the case where Alice has two peers: o her desk phone (1234) o her cell phone (5678) Alice might store the following in the overlay at resource "alice@dht.example.com". 3.3. Access Control In order to prevent hijacking or other misuse, registrations are subject to access control rules. Two kinds of restrictions apply: - A Store is permitted only for AORs with domain names that fall into the namespaces supported by the RELOAD overlay instance. - Storing requests are performed according to the USER-NODE-MATCH access control policy of RELOAD. Before issuing a Store request to the overlay, any peer SHOULD verify that the AOR of the request is a valid Resource Name with respect to its domain name and the namespaces defined in the overlay configuration document (see Section 3.4). Before a Store is permitted, the storing peer MUST check that: - The AOR of the request is a valid Resource Name with respect to the namespaces defined in the overlay configuration document. - The certificate contains a username that is a SIP AOR which hashes to the Resource-ID it is being stored at. - The certificate contains a Node-ID that is the same as the dictionary key it is being stored at. Note that these rules permit Alice to forward calls to Bob without his permission. However, they do not permit Alice to forward Bob’s calls to her. See Section 8.2.2 for additional descriptions. 3.4. Overlay Configuration Document Extension The use of a SIP-enabled overlay MAY be restricted to users with AORs from specific domains. When deploying an overlay service, providers can decide about these use case scenarios by defining a set of namespaces for admissible domain names. This section extends the overlay configuration document by defining new elements for patterns that describe a corresponding domain name syntax. A RELOAD overlay can be configured to accept store requests for any AOR, or to apply domain name restrictions. For the latter, an enumeration of admissible domain names including wildcarded name patterns of the following form MAY be configured. Example of Domain Patterns: dht\.example\.com .*\.my\.name In this example, any AOR will be accepted that is either of the form <user>@dht.example.com, or ends with the domain "my.name". When restrictions apply and in the absence of domain patterns, the default behavior is to accept only AORs that exactly match the domain name of the overlay. Otherwise, i.e., when restrictions are not configured (attribute enable not set), the default behavior is to accept any AOR. In the absence of a <domain-restrictions> element, implementors SHOULD assume this default value. Encoding of the domain name complies to the restricted ASCII character set without character escaping as defined in Section 19.1 of [RFC3261]. The <domain-restrictions> element serves as a container for zero to multiple <pattern> sub-elements. A <pattern> element MAY be present if the "enable" attribute of its parent element is set to true. Each <pattern> element defines a pattern for constructing admissible resource names. It is of type xsd:string and interpreted as a regular expression according to "POSIX Extended Regular Expression" (see the specifications in [IEEE-Posix]). The Relax NG Grammar for the AOR Domain Restriction reads: ```xml <!-- AOR DOMAIN RESTRICTION URN SUB-NAMESPACE --> <!-- AOR DOMAIN RESTRICTION ELEMENT --> Kind-parameter &= element sip:domain-restriction { attribute enable { xsd:boolean } <!-- PATTERN ELEMENT --> element pattern { xsd:string }* } ``` 4. Looking up an AOR 4.1. Finding a Route to an AOR A RELOAD user, member of an overlay, who wishes to call another user with given AOR SHALL proceed in the following way: AOR is GRUU? If the AOR is a GRUU for this overlay, the callee can be contacted directly as described in Section 6. AOR domain is hosted in overlay? If the domain part of the AOR matches a domain pattern configured in the overlay, the user can continue to resolve the AOR in this overlay. The user MAY choose to query the DNS service records to search for additional support of this domain name. AOR domain not supported by overlay? If the domain part of the AOR is not supported in the current overlay, the user SHOULD query the DNS (or other discovery services at hand) to search for an alternative overlay that services the AOR under request. Alternatively, standard SIP procedures for contacting the callee SHOULD be used. AOR inaccessible? If all of the above contact attempts fail, the call fails. The procedures described above likewise apply when nodes are simultaneously connected to several overlays. 4.2. Resolving an AOR A RELOAD user that has discovered a route to an AOR in the current overlay SHALL execute the following steps. 1. Perform a Fetch for Kind SIP-REGISTRATION at the Resource-ID corresponding to the AOR. This Fetch SHOULD NOT indicate any dictionary keys, so that it will fetch all the stored values. 2. If any of the results of the Fetch are non-GRUU AORs, then repeat step 1 for that AOR. 3. Once only GRUUs and destination lists remain, the peer removes duplicate destination lists and GRUUs from the list and initiates SIP or SIPS connections to the appropriate peers as described in the following sections. If there are also external AORs, the peer follows the appropriate procedure for contacting them as well. 5. Forming a Direct Connection Once the peer has translated the AOR into a set of destination lists, it then uses the overlay to route AppAttach messages to each of those peers. The "application" field MUST be either 5060 to indicate SIP or 5061 for using SIPS. If certificate-based authentication is in use, the responding peer MUST present a certificate with a Node-ID matching the terminal entry in the route list. Note that it is possible that the peers already have a RELOAD connection mutually established. This MUST NOT be used for SIP messages unless it is a SIP connection. A previously established SIP connection MAY be used for a new call. Once the AppAttach succeeds, the peer sends plain or (D)TLS encrypted SIP messages over the connection as in normal SIP. A caller MAY choose to contact the callee using SIP or secure SIPS, but SHOULD follow a preference indicated by the callee in its contact_prefs attribute (see Section 3.2). A callee MAY choose to listen on both SIP and SIPS ports and accept calls from either SIP scheme, or select a single one. However, a callee that decides to accept SIPS calls, only, SHOULD indicate its choice by setting the corresponding attribute in its contact_prefs. 6. Using GRUUs Globally Routable User Agent Uris (GRUUs) [RFC5627] have been designed to allow direct routing without the indirection of a SIP proxy function. The concept is transferred to RELOAD overlays as follows. GRUUs in RELOAD are constructed by embedding a base64-encoded destination list in the gr URI parameter of the GRUU. The base64 encoding is done with the alphabet specified in table 1 of [RFC4648] with the exception that `~` is used in place of `=`. Example of a RELOAD GRUU: alice@example.com;gr=MDEyMzQ1Njc4OTAxMjM0NTY3ODk~ GRUUs do not require to store data in the Overlay Instance. Rather when a peer needs to route a message to a GRUU in the same P2P overlay, it simply uses the destination list and connects to that peer. Because a GRUU contains a destination list, it MAY have the same contents as a destination list stored elsewhere in the resource dictionary. Anonymous GRUUs [RFC5767] are constructed analogously, but require either that the enrollment server issues a different Node-ID for each anonymous GRUU required, or that a destination list be used that includes a peer that compresses the destination list to stop the Node-ID from being revealed. 7. SIP-REGISTRATION Kind Definition This section defines the SIP-REGISTRATION Kind. Name SIP-REGISTRATION Kind IDs The Resource Name for the SIP-REGISTRATION Kind-ID is the AOR of the user. The data stored is a SipRegistration, which can contain either another URI or a destination list to the peer which is acting for the user. Data Model The data model for the SIP-REGISTRATION Kind-ID is dictionary. The dictionary key is the Node-ID of the storing peer. This allows each peer (presumably corresponding to a single device) to store a single route mapping. Access Control USER-NODE-MATCH. Note that this matches the SIP AOR against the rfc822Name in the X509v3 certificate. The rfc822Name does not include the scheme so that the "sip:" prefix needs to be removed from the SIP AOR before matching. Data stored under the SIP-REGISTRATION Kind is of type SipRegistration. This comes in two varieties: - sip_registration_uri a URI which the user can be reached at. - sip_registration_route a destination list which can be used to reach the user’s peer. 8. Security Considerations 8.1. RELOAD-Specific Issues This Usage for RELOAD does not define new protocol elements or operations. Hence no new threats arrive from message exchanges in RELOAD. This document introduces an AOR domain restriction function that must be surveyed by the storing peer. A misconfigured or malicious peer could cause frequent rejects of illegitimate storing requests. However, domain name control relies on a lightweight pattern matching and can be processed prior to validating certificates. Hence no extra burden is introduced for RELOAD peers beyond loads already present in the base protocol. 8.2. SIP-Specific Issues 8.2.1. Fork Explosion Because SIP includes a forking capability (the ability to retarget to multiple recipients), fork bombs are a potential DoS concern. However, in the SIP usage of RELOAD, fork bombs are a much lower concern than in a conventional SIP Proxy infrastructure, because the calling party is involved in each retargeting event. It can therefore directly measure the number of forks and throttle at some reasonable number. 8.2.2. Malicious Retargeting Another potential DoS attack is for the owner of an attractive AOR to retarget all calls to some victim. This attack is common to SIP and difficult to ameliorate without requiring the target of a SIP registration to authorize all stores. The overhead of that requirement would be excessive and in addition there are good use cases for retargeting to a peer without its explicit cooperation. 8.2.3. Misuse of AORs A RELOAD overlay and enrollment service that liberally accept registrations for AORs of domain names unrelated to the overlay instance and without further justification, eventually store presence state for misused AORs. An attacker could hijack names, register a bogus presence and attract calls dedicated to a victim that resides within or outside the Overlay Instance. A hijacking of AORs can be mitigated by restricting the name spaces admissible in the Overlay Instance, or by additional verification actions of the enrollment service. To prevent an (exclusive) routing to a bogus registration, a caller can in addition query the DNS (or other discovery services at hand) to search for an alternative presence of the callee in another overlay or a normal SIP infrastructure. 8.2.4. Privacy Issues All RELOAD SIP registration data is public. Methods of providing location and identity privacy are still being studied. Location privacy can be gained from using anonymous GRUUs. 9. IANA Considerations 9.1. Data Kind-ID IANA shall register the following code point in the "RELOAD Data Kind-ID" Registry (cf., [I-D.ietf-p2psip-base]) to represent the SIP-REGISTRATION Kind, as described in Section 7. [NOTE TO IANA/RFC-EDITOR: Please replace RFC-AAAA with the RFC number for this specification in the following list.] +---------------------+------------+----------+ | Kind | Kind-ID | RFC | +---------------------+------------+----------+ | SIP-REGISTRATION | 1 | RFC-AAAA | +---------------------+------------+----------+ 9.2. XML Name Space Registration This document registers the following URI for the config XML namespace in the IETF XML registry defined in [RFC3688] Registrant Contact: The IESG XML: N/A, the requested URI is an XML namespace 10. Acknowledgments This document was generated in parts from initial drafts and discussions in the early specification phase of the P2PSIP base protocol. Significant contributions (in alphabetical order) were from David A. Bryan, James Deverick, Marcin Matuszewski, Jonathan Rosenberg, and Marcia Zangrilli, which is gratefully acknowledged. Additional thanks go to all those who helped with ideas, discussions, and reviews, in particular (in alphabetical order) Michael Chen, Marc Petit-Huguenin, Brian Rosen, and Matthias Waehlisch. 11. References 11.1. Normative References 11.2. Informative References Appendix A. Third Party Registration In traditional SIP, the mechanism of a third party registration (i.e., an assistant acting for a boss, changing users register a role-based AOR, ...) is defined in Section 10.2 of [RFC3261]. This is a REGISTER which uses the URI of the third-party in its From header and cannot be translated directly into a P2PSIP registration, because only the owner of the certificate can store a SIP-REGISTRATION in a RELOAD overlay. A way to implement third party registration is by using the extended access control mechanism USER-CHAIN-ACL defined in [I-D.ietf-p2psip-share]. Creating a new Kind "SIP-3P-REGISTRATION" that is ruled by USER-CHAIN-ACL allows the owner of the certificate to delegate the right for registration to individual third parties. In this way, original SIP functionality can be regained without weakening the security control of RELOAD. Appendix B. Change Log B.1. Changes since draft-ietf-p2psip-sip-08 - Added the handling of SIPS - Specified use of Posix regular expressions in configuration document - Added IANA registration for namespace - Editorial polishing - Updated and extended references B.2. Changes since draft-ietf-p2psip-sip-07 - Cleared open issues - Clarified use cases after WG discussion - Added configuration document extensions for configurable domain names - Specified format of contact_prefs - Clarified routing to AORs - Extended security section - Added Appendix on Third Party Registration - Added IANA code points - Editorial polishing - Updated and extended references B.3. Changes since draft-ietf-p2psip-sip-06 Added Open Issue Authors’ Addresses Cullen Jennings Cisco 170 West Tasman Drive MS: SJC-21/2 San Jose, CA 95134 USA Phone: +1 408 421-9990 Email: fluffy@cisco.com Bruce B. Lowekamp Skype Palo Alto, CA USA Email: bbl@lowekamp.net Eric Rescorla RTFM, Inc. 2064 Edgewood Drive Palo Alto, CA 94303 USA Phone: +1 650 678 2350 Email: ekr@rtfm.com Salman A. Baset Columbia University 1214 Amsterdam Avenue New York, NY USA Email: salman@cs.columbia.edu Henning Schulzrinne Columbia University 1214 Amsterdam Avenue New York, NY USA Email: hgs@cs.columbia.edu Thomas C. Schmidt (editor) HAW Hamburg Berliner Tor 7 Hamburg 20099 Germany Email: schmidt@informatik.haw-hamburg.de Anycast, Multicast or Broadcast Bootstrap Nodes for REsource LOcation And Discovery (RELOAD) draft-petithuguenin-p2psip-reload-one-to-many-00 Abstract This document describes an extension to REsource LOcation And Discovery (RELOAD) that permits to contact a bootstrap node using an Anycast, Multicast or Broadcast IP address. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to format it for publication as an RFC or to translate it into languages other than English. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on July 18, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust’s Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction .............................................. 3 2. Terminology ............................................. 3 3. Searching for Bootstrap Node ............................. 3 4. Acknowledgments .......................................... 4 5. Security Considerations ................................. 4 6. IANA Considerations ....................................... 4 7. Normative References ..................................... 5 Appendix A. Example .......................................... 5 Author’s Address .............................................. 6 1. Introduction RELOAD [I-D.ietf-p2psip-base] explains that to join an overlay a node must, if the bootstrap node cache is empty, contact one of the bootstrap peers listed in a <bootstrap-node> element of the configuration document. The process described works only with unicast addresses, as TCP - and so TLS - is not supported with anything else than unicast addresses, and DTLS does not work at all with multicast or broadcast addresses, and will be unreliable with anycast addresses. 2. Terminology The key words "MUST" and "MAY" in this document are to be interpreted as described in [RFC2119]. One-to-many Address: An Anycast, Multicast or Broadcast IP address. 3. Searching for Bootstrap Node An overlay that runs one or more bootstrap node over a one-to-many address MUST add a <bootstrap-node> element for each of them in the configuration document, using the XML namespace designating them as such. The same configuration document MAY also contain unicast <bootstrap-node> elements to let nodes that do not implement this specification join the overlay. The RELAX NG grammar for the one-to-many <bootstrap-node> element is as follow. Whitespace and case processing MUST follow the rules of [OASIS.relax-ng] and XML Schema Datatypes [W3C.REC-xmlschema-2-20041028]. ```xml namespace otm = "http://implementers.org/reload-one-to-many" parameter &= element otm:bootstrap-node { attribute address { xsd:string }, attribute port { xsd:int }? }* ``` The <bootstrap-node> element has an attribute called "address" that contains an IPv4 or IPv6 address and an optional attribute called "port" that represents the port and defaults to 6084. The IPv6 address MUST use the hexadecimal form using standard period and colon separators as specified in [RFC5952]. More than one "bootstrap-node" element MAY be present. Instead of the bootstrap node, a STUN [RFC5389] server implementing the ALTERNATE-SERVER Mechanism (Section 11) MUST run on the one-to-many address. The STUN server only serves Binding Request and the ALTERNATE-SERVER attribute returned MUST contain the unicast address and the port of a bootstrap node. Credentials MUST NOT be required by the STUN server. If no cached bootstrap nodes are available, a joining node that implements this specification MUST first try to join the bootstrap nodes designated as listening on a one-to-many address. If trying to contact all the one-to-many addresses fails, the joining node MUST try the eventual unicast bootstrap nodes listed in the configuration document. The joining node MUST send a STUN Binding Request to one of the one-to-many addresses, chosen randomly. Any response other than a 300 will put the one-to-many address in a blacklist for 3 minutes, and the joining node MUST try the next one-to-many address. The IP address and port returned in a 300 response MUST be used as if a unicast bootstrap address was retrieved from the configuration file, and MAY be cached the same way a unicast bootstrap node address is cached. As a consequence of this design, a bootstrap node running on a unicast address do not have to listen for other protocols than the Overlay Link protocols defined in RELOAD. A client that need to know the Node-ID of the bootstrap node can send a Probe or Ping request over DTLS-UDP-SR, TLS-TCP-FH-NO-ICE or DTLS-UDP-SR-NO-ICE with a destination list containing a single wildcard Node-ID. After this, the standard process to join the overlay described in [I-D.ietf-p2psip-base] can be used. 4. Acknowledgments Some of the text in this document was taken from version 23 of [I-D.ietf-p2psip-base], authored by Cullen Jennings, Bruce B. Lowekamp, Eric Rescorla, Salman A. Baset and Henning Schulzrinne. 5. Security Considerations 6. IANA Considerations If this document is accepted as a standard track document this section will request a URN in the "XML Namespaces" class of the "IETF XML Registry" from IANA. Until this is done, implementations should use the following URN: http://implementers.org/reload-one-to-many 7. Normative References [I-D.ietf-p2psip-base] Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and H. Schulzrinne, "REsource LOcation And Discovery (RELOAD) Base Protocol", draft-ietf-p2psip-base-23 (work in progress), November 2012. [OASIS.relax_ng] Bray, T. and M. Murata, "RELAX NG Specification". [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, "Session Traversal Utilities for NAT (STUN)", RFC 5389, October 2008. Address Text Representation", RFC 5952, August 2010. [W3C.REC-xmlschema-2-20041028] Recommendation REC-xmlschema-2-20041028, October 2004, Appendix A. Example The following example shows that an anycast address and a multicast address can be used to find a bootstrap node. A joining node that does not recognize the extension can still join the overlay by using the unicast addresses. <?xml version="1.0" encoding="UTF-8" ?> <overlay xmlns="urn:ietf:params:xml:ns:p2p:config-base" xmlns:otm="http://implementers.org/reload-one-to-many"> <configuration instance-name="overlay.example.org" sequence="22" expiration="2002-10-10T07:00:00Z"> <bootstrap-node address="192.0.0.1" port="6084" /> <bootstrap-node address="192.0.2.2" port="6084" /> <bootstrap-node address="2001:DB8::1" port="6084" /> <otm:bootstrap-node address="192.0.0.1" /> <otm:bootstrap-node address="233.252.0.1" port="6084" /> </configuration> <signature> VGhpcyBpcyBub3QgcmlnaHQhCg== </signature> </overlay> Author’s Address Marc Petit-Huguenin Impedance Mismatch Email: petithug@acm.org Abstract This document defines two new Overlay Link protocols to be used with REsource LOcation And Discovery (RELOAD), both using SCTP. The Overlay Link protocol DTLS-SCTP-NO-ICE uses DTLS on top of native SCTP for overlays that do not require the use of ICE. The Overlay Link protocol DTLS-SCTP-UDP uses DTLS on top of an UDP encapsulation of SCTP for overlays that require the use of ICE. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 21, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. Table of Contents 1. Introduction .................................................. 2 2. Terminology .................................................. 2 3. DTLS-SCTP-NO-ICE Overlay Link Protocol ....................... 3 4. DTLS-SCTP-UDP Overlay Link Protocol .......................... 3 5. Security Considerations ........................................ 3 6. IANA Considerations ........................................... 3 7. Normative References .......................................... 3 1. Introduction RELOAD [I-D.ietf-p2psip-base] defines 3 Overlay Link protocols, DTLS-UDP-SR, TLS-TCP-FH-NO-ICE and DTLS-UDP-SR-NO-ICE but none of them prevents Head of Line (HoL) blocking. DTLS for SCTP [RFC6083], is a good candidate as Overlay Link protocol, but because most NATs cannot handle SCTP [RFC4960], it can only been used with overlays that are known to not have nodes behind a NAT. For overlays that may have nodes behind a NAT, a UDP encapsulation of SCTP [I-D.ietf-tsvwg-sctp-udp-encaps] is used in place of the native SCTP, so it can traverses NAT Additionnaly using a UDP encapsulation does not require to define how using SCTP in ICE. 2. Terminology The key words "MUST" and "MUST NOT" in this document are to be interpreted as described in [RFC2119]. 3. DTLS-SCTP-NO-ICE Overlay Link Protocol This overlay link protocol consists of DTLS over SCTP, as specified in [RFC6083]. The RELOAD messages MUST be sent on a stream other than 0 (which is reserved for the DTLS ChangeCipherSpec, Alert and Handshake protocols), with unlimited reliability but without the ordered delivery feature. The Framing Header or the Simple Reliability protocols described in RELOAD MUST NOT be used. 4. DTLS-SCTP-UDP Overlay Link Protocol This overlay link protocol consists of DTLS over an UDP encapsulation of SCTP, as specified in [RFC6083] and [I-D.ietf-tsvwg-sctp-udp-encaps]. The RELOAD messages MUST be sent on a stream other than 0 (which is reserved for the DTLS ChangeCipherSpec, Alert and Handshake protocols), with unlimited reliability but without the ordered delivery feature. The Framing Header or the Simple Reliability protocols described in RELOAD MUST NOT be used. 5. Security Considerations TBD. 6. IANA Considerations If this document is accepted as a standard track document this section will request that IANA assign codes for the DTLS-SCTP-NO-ICE and DTLS-SCTP-UDP overlay protocols. Until this is done, implementations should use code 5 (reserved for experimentations as EXP-LINK). Using the same code is not an issue in this case as ICE and NO-ICE Overlays Protocols cannot be be simultaneously used in the same overlay. [[Do we need to also assign a PPID?]] 7. Normative References [I-D.ietf-p2psip-base] [I-D.ietf-tsvwg-sctp-udp-encaps] Author’s Address Marc Petit-Huguenin Impedance Mismatch Email: petithug@acm.org
Biomonitoring in the Era of the Exposome. Kristine K. Dennis, Emory University Elizabeth Marder, Emory University David M. Balshaw, National Institutes of Health Yuxia Cui, National Institutes of Health Michael A. Lynes, University of Connecticut Gary J. Patti, Washington University Stephen M. Rappaport, University of California Berkeley Daniel T. Shaughnessy, National Institutes of Health Martine Vrijheid, Centre for Research in Environmental Epidemiology Dana Barr, Emory University Journal Title: Environmental Health Perspectives Volume: Volume 125, Number 4 Publisher: National Institute of Environmental Health Sciences (NIEHS) | 2017-04, Pages 502-510 Type of Work: Article | Final Publisher PDF Publisher DOI: 10.1289/EHP474 Permanent URL: https://pid.emory.edu/ark:/25593/s19rt Final published version: http://dx.doi.org/10.1289/EHP474 Copyright information: Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged Accessed September 15, 2017 8:48 AM EDT Biomonitoring in the Era of the Exposome Kristine K. Dennis, Elizabeth Marder, David M. Balshaw, Yuxia Cui, Michael A. Lynes, Gary J. Patti, Stephen M. Rappaport, Daniel T. Shaughnessy, Martine Vrijheid, and Dana Boyd Barr 1Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; 2Exposure, Response, and Technology Branch, Division of Extramural Research and Training, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA; 3Department of Molecular and Cell Biology, College of Liberal Arts and Sciences, University of Connecticut, Storrs, Connecticut, USA; 4Department of ChemInformatics, Department of Medicine, Washington University, St. Louis, Missouri, USA; 5Department of Environmental Health Sciences, School of Public Health, University of California, Berkeley, Berkeley, California, USA; 6Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain INTRODUCTION More than ten years ago, shortly after the human genome was sequenced, Christopher Wild proposed an environmental complement to the genome in determining risk of disease, termed the exposome. He defined the exposome as the totality of exposures throughout the lifespan (Wild 2005). Since the exposome was originally defined, research efforts have begun, leading to a revised working definition that may be summarized by the following elements. The exposome includes the cumulative measure of exposures to both chemical and nonchemical agents such as diet, stress, and sociobehavioral factors. It includes a series of quantitative and repeated metrics of exposures—both endogenous and exogenous—that describe, holistically, environmental influences or exposure over a lifetime (from conception to death). The exposome can include traditional measures of exposure (e.g., traditional biomonitoring, environmental monitoring) but also includes targeted discovery of unknown chemicals of biological importance (Miller and Jones 2014; Rappaport and Smith 2010; Wild 2005, 2012). Exposomic approaches go a step beyond traditional biomonitoring, aiming to capture all exposures that potentially affect health and disease. As a cancer epidemiologist, Wild understood the importance of the environment to health and that current disease trends cannot be explained by genetics alone (Wild 2005). We are only beginning to understand the complexities of environmental exposures and their impacts on human health, whereas genetic influences on health have been extensively studied. At present, we have limited estimates of the impact of environmental exposures on health, and uncertainty exists even in those (Jones 2016; Rappaport 2016; Rappaport and Smith 2010). Biomonitoring serves as a key tool to define exposure—disease risks given the biological significance of internal exposure measurements. With the continued advancement of methods, biomonitoring strategies will be critical in achieving a comprehensive understanding of exposures that have personal and public health relevance. With full understanding of the complex interactions between genetics and environmental exposures, the mysteries of the etiology, trends, and prevention of many diseases can be solved. In an effort to advance the framework for developing exposome approaches and characterization, a diverse group of scientists gathered at the National Institute of Environmental Health Sciences (NIEHS) Exposome Workshop in January 2015 to discuss the current state of the science and to provide recommendations to the environmental health sciences community on how to best advance exposome research. The state of the science along with the perspectives and recommendations of our working group, Biomonitoring for the Exposome, are described here. DISCUSSION Traditional Biomonitoring Exposure is commonly assessed by a spectrum of questionnaire data and ecological, environmental, or biological measurements. Note to readers with disabilities: EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact: ehponline@niehs.nih.gov. Our staff will work with you to assess and meet your accessibility needs within 3 working days. BACKGROUND: The term “exposome” was coined in 2005 to underscore the importance of the environment to human health and to bring research efforts in line with those on the human genome. The ability to characterize environmental exposures through biomonitoring is key to exposome research efforts. OBJECTIVES: Our objectives were to describe why traditional and nontraditional (exposomic) biomonitoring are both critical in studies aiming to capture the exposome and to make recommendations on how to transition exposure research toward exposomic approaches. We describe the biomonitoring needs of exposome research and approaches and recommendations that will help fill the gaps in the current science. DISCUSSION: Traditional and exposomic biomonitoring approaches have key advantages and disadvantages for assessing exposure. Exposomic approaches differ from traditional biomonitoring methods in that they can include all exposures of potential health significance, whether from endogenous or exogenous sources. Issues of sample availability and quality, identification of unknown analytes, capture of nonpersistent chemicals, integration of methods, and statistical assessment of increasingly complex data sets remain challenges that must continue to be addressed. CONCLUSIONS: To understand the complexity of exposures faced throughout the lifespan, both traditional and nontraditional biomonitoring methods should be used. Through hybrid approaches and the integration of emerging techniques, biomonitoring strategies can be maximized in research to define the exposome. http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 http://dx.doi.org/10.1289/EHP474 Biological measures of exposure that determine an internalized dose are often preferred because they are usually more relevant to the health outcome studied. Traditional biological measurements, also called targeted analyses, measure a target chemical, metabolite, or reaction product in a biological medium such as urine or blood (see Appendix 1). These traditional biomonitoring measurements have become a key component of exposure assessment in many epidemiologic studies that attempt to link exposures to health outcomes. Molecular epidemiology studies and regulatory agencies rely primarily on targeted analyses because of their current availability and historical use. Broad surveys such as the National Health and Nutrition Examination Study (NHANES) utilize these methods, allowing for quantification and longitudinal surveillance of known exposures across the U.S. population. NHANES data facilitate comparative identification of abnormal exposure levels in select population subsets. Major epidemiology studies such as those evaluating blood lead levels and mean IQ in children and prenatal pesticide exposures and neurological deficits in children and neurodegenerative disease in adults have linked significant health outcomes to specific exposures, informing opportunities for further mechanistic studies (Chin-Chan et al. 2015; Kaufman et al. 2014; Rosas and Eskenazi 2008). Other federal efforts in the United States include the National Biomonitoring Program (NBp) of the Division of Laboratory Sciences at the Centers for Disease Control and Prevention (CDC). The NBp produces a National Report on Human Exposure to Environmental Chemicals and regularly updates the NHANES biomonitoring data in that report (CDC 2009, 2015). Chemicals of potential concern such as arsenic, perchlorate, and environmental phenols, among others, continue to be added to NHANES, with the most recent report including data on > 250 chemicals. The CDC also provides grant funding to a variety of state laboratories to increase public health laboratory capacity for surveillance. Targeted analytical capabilities and worldwide use continue to expand through both public health and academic entities. **Historical use of biomonitoring.** Traditional biomonitoring methods are well established for exposure assessment in epidemiology studies and in federal and state surveillance activities. Because of their historical use, they provide a number of strong advantages for exposure research (see Appendix 2). Biologically persistent chemicals are well-characterized with traditional methods, whereas short-lived chemicals are effectively measured only if the individual is undergoing continuous or continual exposures or if the timing of exposures is known. Chemicals such as phthalates, bisphenols, and parabens are well-characterized by targeted methods given their widespread use and presence in the environment. Often, chemicals of particular toxicological interest may be difficult to measure owing to barriers such as stability or presence in readily accessible biological matrices such as blood or urine. For example, short-lived chemicals such as various current-use pesticide and phthalate metabolites can only be detected in urine samples if exposure occurs within a few days of testing; therefore, continuous or longitudinal sample collection is necessary to capture exposure. For a selected group of 250–300 known persistent (30–40%) and nonpersistent (60–70%) chemicals, sample analysis provides exposure information for the chemical of concern within a specific window of exposure; reference data are available for most of these chemicals (CDC 2015). The ~250 chemicals that are commonly measured in the United States are primarily driven by the CDC biomonitoring list of target analytes (CDC 2015). Most other programs also follow the CDC list because selection of these agents was informed by a public nomination process followed by expert ranking of the nominated chemicals (CDC 2012). An important caveat of this process is that the target list is partially based on ease of performance and compatibility with existing methods. Another concern is that some of the chemicals have little toxicological relevance or diminishing exposure across the population resulting from successful regulation of their release into the environment, or a combination of the two. **Biomonitoring methods.** Although method development for traditional biomonitoring can be quite rigorous, this also translates into a slow and expensive process when developing analysis protocols for new chemicals of interest. These analyses often require relatively high volumes of sample, typically 0.5–1 mL for a single method (~ 10 mL urine and > 20 mL serum to measure the 250–300 currently biomonitored chemicals), which can be limiting for certain biospecimen types and age groups under study. For exposome research, these requirements restrict the number and types of chemicals that can be measured at any one time. Unknown or suspected chemicals of concern may not be measured or identifiable through targeted methods (see Appendix 2) (Rappaport et al. 2014); yet targeted analyses are valuable given the accuracy and depth at which a chemical of interest can be assessed. By coupling traditional biomonitoring methods with broader exposomic approaches, the benefits of both strategies can be fully realized. **Exposomic Approaches** An exposomic approach differs from traditional biomonitoring in that it can theoretically include all exposures of potential health significance, whether they are derived from exogenous sources (e.g., pollutants, diet, drugs) or endogenous sources (e.g., hormones, human and microbial metabolites) (Rappaport and Smith 2010; Rappaport et al. 2014). Because levels of chemicals in blood or other biospecimens reflect a wide range of exposures or the metabolic consequences of exposures, including psychosocial stress, other nonchemical stressors such as noise, and nutritional factors, exposomic biomonitoring offers an efficient means for characterizing individual exposure profiles. Incorporating the exposome paradigm into traditional biomonitoring approaches offers a means to improve exposure assessment in many ways (Wild 2012). **Untargeted analyses.** With only a few hundred chemicals routinely assessable through targeted methods and with limitations for short-lived compounds, exposomic approaches are critical to understanding the thousands of chemicals people are exposed to daily through direct chemical exposures or consequences of exposure (e.g., cortisol levels due to stress or noise exposures) (CDC 2015). Through untargeted biomonitoring approaches such as high-resolution metabolomics (HRM), > 1,500 metabolites can be monitored with a relatively small amount of biological specimen (~ 100 μL) and for the cost of a single traditional biomonitoring analysis of 8–10 target chemicals (Johnson et al. 2010; Jones 2016). Untargeted analyses of small molecules or macromolecular adducts in blood, urine, or other matrices are well suited for exposome-wide association studies (EWAS), which compare profiles of hundreds or thousands of chemical features—analogous to ions with a given mass-to-charge ratio and a specified retention time in traditional biomonitoring—between diseased and healthy subjects (Rappaport 2012, 2016). Indeed, untargeted analyses performed using the current generation of liquid chromatography–high resolution mass spectrometers (LC-HRMs) can detect > 30,000 small-molecule features (Ivanisevic et al. 2013) and > 100 human serum albumin (HSA) adducts of reactive electrophilic chemicals (including reactive oxygen species) at the nucleophilic locus Cys34 (Grigoryan et al. 2012; Rappaport et al. 2012). Processing the rich sets of data from untargeted analyses of archived biospecimens offers a path for discovering health-impairing exposures that have thus far escaped scrutiny, a largely unrecognized benefit of exposomics. It is important to note that full annotation of molecular features is not required. for case–control comparisons provided that LC-HRMS signatures are available (e.g., accurate mass, retention time, and MS/MS fragmentation). Archived biospecimens from well-designed cohort studies already exist. With continued advancement in untargeted analyses, there is potential to make significant advances in human health through uncovering unknown exposures (da Silva et al. 2015; Zhou et al. 2012). High-resolution metabolomics. Although untargeted analyses encompass a wide range of the -omics techniques, HRM is a technique that is poised to advance exposomics research because of the breadth of coverage it offers of both endogenous and exogenous chemicals. At the present time, it is routine to detect tens of thousands of features with HRM, and this number will increase as the sensitivity of mass analyzers continues to improve. These features do not necessarily represent different chemical constituents but provide extensive data for evaluation of alterations in biological pathways (Mahieu et al. 2014). Extensive comparisons of the features of these various instruments are available elsewhere (Marshall and Hendrickson 2008). With the additional advancements that have been made in bioinformatics methods to aid in feature extraction and data analysis, HRM has become an increasingly viable tool for broad exposome-level characterization (Jones 2016). Although features linked to human health will require chemical identification, the technology is in place for the feature extraction methods and annotation efforts that will increase the total number of chemicals that can be monitored (Soltow et al. 2013). Researchers are already demonstrating this expanded potential along with the ability to quantify chemicals under a high-resolution metabolomics platform (Go et al. 2015; Li et al. 2015). By definition, untargeted approaches are agnostic, allowing unknown or emerging exposures of concern (see Appendix 3) to be detected. These approaches are often hypothesis-generating and may require testing of newly discovered analytes/exposures in experimental models to confirm effects on biological responses. Detection of low-level xenobiotic exposures. Persistent challenges exist with detecting chemicals present at low levels, defining reference values of “normal” exposure, and ultimately linking these measures to an exogenous source so intervention can occur. Because blood concentrations of xenobiotics (femtomolar to micromolar) tend to be much lower than those of chemicals derived from food, drugs, and endogenous sources (nanomolar to micromolar), untargeted analyses of xenobiotics are not as efficient and reliable as those of ingested and endogenous sources at detecting many exposures of interest (Rappaport et al. 2014). To determine the health impacts of these exposures, it will be necessary to develop semi-targeted or multiplexed methods that increase the signals of exogenous molecules relative to those of endogenous origin (Rappaport et al. 2014; Southam et al. 2014; Wei et al. 2010). Analyses of suspected chemicals of concern, also referred to as suspect screening, can be prioritized through measuring panels of chemicals with known biological effects but without identifying a specific hypothesis regarding the toxicological pathway. Untargeted and suspected chemical analyses both fall under exposomic biomonitoring and offer extraordinary potential for increased understanding of complex chemical exposures. Hybrid approaches. Various terms are used to describe hybrid approaches, including suspect screening or semi-targeted analyses. Because both targeted and untargeted approaches have beneficial attributes as well as drawbacks, using a hybrid exposomics approach may enable us to exploit advantages while minimizing the limitations of each technique. One of the obvious limitations of a targeted approach is its inability to provide exposure information on a wide array of chemicals. However, targeted analysis can typically provide validated and quality-assured detection and quantification at very low concentrations that may not be available using an untargeted approach until HRM and the necessary bioinformatic data extraction techniques mature. As mentioned above, the development of these quantitative techniques for HRM is underway with advancements in instrumention (Go et al. 2015; Marshall and Hendrickson 2008). Furthermore, the generic extraction methods used in untargeted analysis may not be able to capture all of the chemicals of interest (e.g., limited extraction of nonpolar chemicals using a typically polar solvent extraction), whereas more specialized extractions can specifically target chemical classes. Semi-targeted analysis. Semi-targeted analysis can utilize various approaches including a two-step strategy: discovery using metabolomics followed by a more fully quantitative targeted measure. Another potential approach would involve a known or measured chemical exposure in individuals for which metabolomic measurements could also be made. For instance, untargeted metabolomic analysis of each group would then allow for a search for new exposure biomarkers and unique metabolic pathway perturbations to help elucidate the effect mechanism. Traditionally, targeted analysis data have been used for risk assessment purposes, so shifting solely to a newer platform may take some time. The hybrid approach can be useful for both exposomic analysis and informing targeted analysis approaches. For example, a targeted chemical concentration can be used as an “outcome” for metabolome-wide association studies (e.g., evaluating biochemical alterations relative to targeted chemical concentrations), or a metabolomic analysis can help identify important chemicals that need to be rigorously quantified for health or risk assessments. Of course, each of the two approaches stands on its own, and they have done so for many decades. By combining the two, however, we have a much more powerful approach to understanding chemical exposures, biological alterations, and disease. Overarching Issues Matrix selection. Whether using a traditional biomonitoring or an exposomic approach, careful attention must be given to which matrices can be practically collected and which matrices are relevant for assessing chemical exposures. The matrices available for collection during different life stages and a nonexhaustive list of the chemicals that are appreciably present in these matrices have been reviewed elsewhere (Barr et al. 2005). Typically, the least-invasive matrix in which the chemicals appreciably collect, such as blood and urine, is the preferred matrix. Although most analysis of exposure is performed with urine or blood samples as a consequence of the ease with which they can be collected, there are other sample types that have begun to be explored for their value in exposome interrogation. For example, saliva, which can be collected from school-age children and adults, is a problematic matrix to collect from infants and toddlers because of choking dangers associated with the collection devices and the inability of young children to actively secrete it. Even if the matrix, in this case saliva, can be noninvasively collected, the target chemical or suite of potential chemicals may not enter the matrix for a variety of reasons, including protein binding of chemicals that prevents their secretion into saliva (Lu et al. 1998). In addition, saliva is nonsterile; therefore, contributions of the oral microbiome can influence the composition of the analytes to be measured. Buccal and nasal swabs have also been used to assess the biological consequences of external exposures. In the same sample types, DNA, mRNA, and their adducts have been the principal focus to date (Beane et al. 2011; Spira et al. 2004; Zhang et al. 2010), but these samples (as well as fecal samples) are also compromised by the presence of a strong microbial community that can influence the composition of the exposome constituents. Other biological samples (e.g., selected blood cells, sweat, teeth, nails) can include information about recent historical exposures in their composition. The use of alternative samples as historical measures of exposure may become important in future studies. Teeth are a matrix that has demonstrated particular promise for characterizing prenatal exposures to metals and to some organic chemicals because of their defined growth patterns (Andra et al. 2015). We can use the “record” of prior exposures recorded in hair, deciduous teeth, or molecular “fingerprints” in other samples to provide historical measures of certain exposures (Arora et al. 2012; Hu et al. 2007); however, validation of the time represented in the exposure history may be laborious. There are limitations to these sample sets because external deposits of specific chemicals can make the interpretation of measured levels in these samples different from those measured in blood, for example. In addition, standardized protocols and reference standards are lacking for many alternative matrices, making standardization of results across studies difficult. An important consideration when choosing samples for exposome-type research is the anticipated presence of the particular chemical(s) in the harvested samples. Because chemicals may display unanticipated pharmacodynamics and biotransformation, it may ultimately be essential that multiple sample types are collected from each individual in the effort to define the exposome. Blood circulates throughout the body, so there is an advantage to its assessment because it has been exposed to the myriad of routes by which an environmental chemical may enter the body. However, some analytes are known to specifically accumulate in particular tissues; thus, a broad-spectrum assessment of multiple patient samples will provide the best insights into exposures. Analytical considerations for matrix effects. In addition to the relevant matrices that can be collected, we must consider the alterations in response that may be obtained in analytic systems related to other components of the matrix. Such matrix effects can enhance analytic signals or work to suppress signals (Panguet et al. 2016). In fact, each individual sample will exert its own matrix effects that can make quantification difficult, particularly in mass spectrometry–based methods. Mass spectrometers are inherently sensitive to matrix effects such that the analytical signal of a given concentration can vary over orders of magnitude if appropriate internal standards for normalizing the mass spectral signal have not been used (Baker et al. 2005). In particular, these variations could present challenges when attempting to quantify features in untargeted analysis approaches. Sample collection and storage. Collection and storage procedures are particularly important considerations for internal exposure measurements. Failures in the proper collection and storage of specimens can result in lost sample integrity, samples that are not suitable for analysis, and contamination/degradation of important chemicals. Because of the sensitivity of some methods such as HRM, biospecimens must be carefully collected and well-maintained. Specific attention to freeze-thaw cycles, potential contamination risks, and collection protocols is needed to ensure that the data extracted from each sample are accurate. It is nearly impossible to control for every preanalytic challenge in sample collection and storage for an untargeted analysis, which is one reason that both targeted and untargeted analyses are quite complementary. In addition, both targeted and untargeted approaches can only measure a limited amount of the exogenous and endogenous chemicals that are present in our bodies. The types and number of chemicals within us that are measureable largely depend on the matrix selected and the method used (Children’s Health Exposure Analysis Resource (CHEAR) 2016a, 2016b). Spatial variability. In addition, it is important to understand how temporal variability may vary over geographic areas and in different exposure scenarios. In this respect, exposure assessment can become very complex. Multiple samples within a population are generally preferred over a single sample so that both temporal and spatial variability can be assessed; however, the collection of multiple samples is often cost-prohibitive and can be an undue burden on participants. To appropriately interpret internal exposure data in the context of risk or health outcome, it is imperative to ascertain the degree of variability in space and time. Pharmacodynamic variability. Ideally, we would have information on variability in pharmacodynamics to potentially evaluate resulting exposure data (e.g., whether a given chemical distributes to tissues differently among individuals). Most of the pharmacodynamic information we have for specific chemicals is derived from animal studies, and these processes may not be the same in humans. In addition to exposure and pharmacokinetic variability, laboratory and sampling variability should also be assessed and, if possible, teased apart from true intra-person variability. Fit-for-purpose use. The “fit-for-purpose” concept has gained popularity in traditional biomonitoring (Lee et al. 2006). This concept addresses the balance between overall cost of analysis and the degree of analytical rigor required to use the internal exposure measure results for a given purpose. In instances where legal implications exist or regulatory decisions are to be made, maximum analytical rigor is required. But for exploratory studies and for many epidemiologic studies, statistical power derived from a larger number of samples, but with sufficient precision to detect differences, is often preferred. In these cases, relaxation of analytical rigor may translate into lower costs that, in turn, could enable the number of samples analyzed to increase. Furthermore, in untargeted approaches, authentic standards are not always necessary to evaluate a chemical’s relationship to disease or alterations in biomolecular concentrations. In addition, many “add-on” studies use samples collected for different analyses for which the sample collection/storage may represent more precision, thus not warranting the increased cost of strict analytical rigor. For each given study or study question, it is important to consider the analysis and the criteria that are necessary to meet the study objectives. For example, if a study seeks to control for smoking but needs validation of the questionnaire, a low-resolution method such as an immunoassay for molecular indications of smoking may be most suitable for the study; this would maximize the money available for other needs in the study. Many times, substantial resources are dedicated to perfecting an analytic method rather than using a portion of those funds to determine which measurements are actually critical to answering a research question. The issue of balance in analytic rigor and cost needs to be addressed in each study. Extant data also represent a “fit-for-purpose” approach. Extant data were often collected to answer a certain set of research questions; thus, they are not always applicable to a different study question. However, extant data do represent a source for generating hypotheses that can be further tested using prospective, longitudinal studies. For example, NHANES data offer a resource to evaluate the extent of U.S. population exposures to particular chemicals and can serve as a tool for the exposure component of risk assessment. Although the data are cross-sectional, they serve as a useful hypothesis-generating resource. **Unknown analytes.** Characterizing unknown analytes remains a major challenge for understanding the exposome. Research efforts should prioritize the development of methods to determine relevant exposures and to identify sources of specific chemical signatures. By linking shifts in the microbiome, the metabolome, the proteome, and so forth to unknown analytes, we can start to determine the profiles of unknown toxicant exposures and their consequences. Additionally, biomonitoring techniques that can assess changes in cellular composition or in the developmental capacity of cells may indicate risks for later health conditions such as cancer and neurodegenerative diseases. Even if the identity of an analyte is unknown, linking unknown exposures to potential disease consequences creates further support for the investment of resources necessary to understanding cumulative lifetime exposures. Annotation of spectra for unknown chemicals can be quite time-consuming and therefore only completed on a select number of features. Limitations regarding chemical annotation will best be overcome through a concerted effort across many research groups to identify, catalogue, and disseminate information related to newly identified small molecules. Additionally, continued focus on bioinformatics techniques to extract information about chemical features of importance will allow semi-targeted approaches to be used for unknown and low-abundance chemicals. The omics technologies all have potential for discovering unknown analytes. Through ongoing advancements in mass spectrometry, low-abundance chemicals can be targeted and characterized. With comprehensive coverage of the metabolome, reference metabolic profiles combined with health outcome data would provide a baseline for identification of unknown analytes with health relevance. Through a concerted effort across laboratories, identification and cataloguing unknown analytes will become a tangible task for advancing the exposome. **Overcoming Gaps and Barriers to Exposome Research** Several data gaps or barriers exist in both targeted and untargeted analyses. For untargeted analyses, the ability to identify and quantify low-abundance analytes—most environmental chemicals—is still immature. Untargeted approaches may need new, more sensitive mass spectrometric approaches or chemoselective probes to improve the detection of low-abundance chemicals. We reemphasize that analytic standards are not required for discovery of new and relevant biomarkers; they become necessary only when a new biomarker is identified and needs to be validated. Although many biomonitoring resources are available through public health and academic laboratories, few laboratories exist with the capacity to measure a wide array of “known” toxicants, particularly in nonstandard matrices (i.e., matrices other than blood and urine) (see Appendix 4). Having access to such capacity is particularly important for new investigators, who may not have established relationships with such laboratories. Additionally, accurate and reproducible measures across laboratories remain a challenge. The CHEAR initiative, led by the National Institute of Environmental Health Sciences, represents a unique opportunity to provide a standardized laboratory network with access to targeted and untargeted analyses of biospecimens and so may serve to fill these gaps (NIEHS 2015). **Databases.** The application of untargeted metabolomics to identify environmental exposures correlated with human health has its own unique challenges. The largest reference databases for metabolomics are the Metabolite and Tandem MS Database (METLIN) and the Human Metabolome Database (HMDB) (Tautenhahn et al. 2012; Wishart et al. 2009). To date, METLIN and HMDB have largely focused on naturally occurring metabolites. To our knowledge, the number of compounds in METLIN and HMDB that may be potentially relevant to exposure studies has not yet been carefully assessed. The number of databases available for metabolomics continues to expand and has unique utility depending on the research question. A more expansive discussion of metabolomics database resources is available (Go 2010). To facilitate large-scale exposome studies, the field may benefit from having a database or from having database search functionalities specifically dedicated to environmental exposure chemicals. As discussed above, discovery experiments are typically most successful when a small subset of features can be targeted for structural identification. Thus, databases and repositories curating information on the human exposome would provide powerful mechanisms for prioritizing features of interest to environmental health scientists. **Bioinformatic Approaches** Although bioinformatics were covered under the scope of the Bioinformatics and Informatics Workgroup at the NIEHS Exposome Workshop, it is worthwhile to mention a few bioinformatic needs that are specific to the development of exposomic biomonitoring approaches. As highlighted throughout this article, characterizing the complexities of the exposome requires use of --- **Appendix 1. Glossary.** <table> <thead> <tr> <th>Term</th> <th>Definition</th> </tr> </thead> <tbody> <tr> <td>Traditional biomonitoring/ targeted analyses</td> <td>Analyses of biological samples for specific chemicals: either exposures or markers of exposures</td> </tr> <tr> <td>Semi-targeted/hybrid approaches</td> <td>Exploits the advantages of both targeted and untargeted analyses: for example, using metabolomics for discovery of potential exposures followed by targeted analysis for a more fully quantitative measure</td> </tr> <tr> <td>Multiplexing</td> <td>Fractionation of samples to remove higher-level chemicals, enabling detection of lower-abundance chemicals</td> </tr> <tr> <td>Untargeted analyses</td> <td>Agnostic analyses that can measure a broad set of endogenous and exogenous metabolites in one sample run</td> </tr> <tr> <td>Feature</td> <td>A raw data output from mass spectrometry analysis which includes an accurate mass-to-charge ratio with associated retention time (RT) and ion intensity; a feature can represent one or more chemicals/metabolites, so data extraction methods are critical to interpretation</td> </tr> <tr> <td>Biomonitoring</td> <td>Can refer to measurement of chemicals through both targeted and untargeted methods</td> </tr> <tr> <td>High-resolution metabolomics</td> <td>A mass spectrometry technique that can detect &gt;10,000 features through instrumentation such as time-of-flight, Fourier transform ion cyclotron resonance and orbitrap mass analysers</td> </tr> <tr> <td>HELIX (The Human Early-Life Exposome)</td> <td>A European-funded project under the Seventh Framework Programme for Research and Technological Development (FP7) Exposome Programme focused on understanding the early-life exposome through novel exposure measurement and data-driven methods</td> </tr> <tr> <td>HERCULES (Health and Exposome Research Center: Understanding Lifetime Exposures)</td> <td>A National Institute of Environmental Health Sciences–funded center at Emory University focused on providing infrastructure and expertise to develop and refine new tools and technologies to advance exposome research as well as on promoting environmental health sciences research overall</td> </tr> <tr> <td>EXPOsOMICS</td> <td>A European-funded project under the FP7 Exposome Programme that aims to develop a new approach to assessing environmental exposures in adults, particularly through the use of omics techniques</td> </tr> <tr> <td>HEALS (Health and Environment-wide Associations based on Large population Surveys)</td> <td>A European Commission–funded project focused on integrating omics data and traditional biomonitoring measurements with alterations in outcomes such as gene expression and metabolic regulation to assess environmental exposures and human health associations</td> </tr> </tbody> </table> broad coverage techniques to link internal biochemical perturbations to external exposures. Bioinformatic requirements for these types of data analyses are substantial, yet they offer a high return on investment. Through pathway analysis and data extraction algorithms, biological pathway perturbations can provide great insight into broad disease processes. Additionally, detection of low-level xenobiotic and unknown chemicals can be greatly enhanced through bioinformatic techniques. Further development of bioinformatic tools and data storage and handling will be key to advancing our understanding of the health impact of complex exposures. Implementing the Exposome External exposures and the actual body burden of said exposures can be quite variable. There is much to be learned about combining external and internal measures to maximize understanding of exposure and how to mitigate exposures that have negative health consequences. Coupling technologies and utilizing real-time monitoring tools can increase our overall understanding of exposures spatially and temporally. Exposome studies in Europe such as The Human Early-life Exposome (HELEX); Health and Environment-wide Association Studies based on Large population Surveys (HEALS); and EXPOSOMICS have started to demonstrate specific approaches for capturing this type of information [Community Research and Development Information Service (CORDIS) 2014, 2015; Vrijheid et al. 2014]. Similarly, Emory University’s NIEHS-funded Human Exposome Research Center: Understanding Lifetime Exposures (HERCULES) has developed infrastructure that has supported several environmental health studies using hybrid biomonitoring approaches (Go et al. 2014, 2015; Jones 2016; Zhang et al. 2014). HELIX also uses a hybrid approach for data collection. HELIX specifically focuses on cohorts of mother-child pairs to better understand which developmental periods may be particularly vulnerable to environmental exposures (Vrijheid et al. 2014). Along with personal external exposure monitoring strategies, traditional biomonitoring techniques have been combined with untargeted omics analyses (e.g., metabolomics, proteomics, transcriptomics, epigenomics) with a particular focus on repeat sampling to capture nonpersistent biomarkers. By performing omics-exposure and omics-health association studies, researchers aim to uncover biologically meaningful omics signatures. The HELIX design is one example of a current approach that integrates traditional and nontraditional techniques to better understand the exposome. Although HELIX offers one initial study structure for understanding the exposome, continued emphasis for exposomic approaches should be placed on developing techniques to measure nonpersistent chemicals that do not place undue burdens on study participants or significant financial constraints on the research study. Recommendations The following recommendations are suggested for approaching internal exposure assessment for exposome research: Recommendation 1: Encourage secondary analyses of samples collected for traditional targeted chemical studies. High-quality samples (i.e., samples that have been collected and stored properly) from longitudinal epidemiology studies should be used for untargeted analysis and alternative measurement techniques. For this aim to be successful, it is critical that methods for sample collection and storage be standardized. Investment should be made in maintaining established cohorts and in developing protocols that optimize stabilization of samples for storage (e.g., does one analyte stabilize actually destabilize other analytes of interest? Would adding a known xenobiotic act as a standard for normalization? Should multiple small aliquots be stored at the time of collection to facilitate different analytical needs?). Recommendation 2: Evaluate and use standardized measurement platforms with measurement harmonization. A general prototype platform or reference samples should be established under which different technologies can be tested. By establishing this platform, researchers can have a standardized way of demonstrating capacity with ### Appendix 2. Key advantages and disadvantages of traditional biomonitoring for determination of exposure. <table> <thead> <tr> <th>Traditional biomonitoring for determination of exposure</th> <th>Advantages</th> <th>Disadvantages</th> </tr> </thead> <tbody> <tr> <td>Well-established and reliable methods for both long-lived (biologically persistent) chemicals and short-lived chemicals with continuous exposures</td> <td>Limited to a select group of known chemicals (~250)</td> <td></td> </tr> <tr> <td>Highly selective methods</td> <td>Studies such as NHANES do not take continuous measures, thereby limiting detection of short-lived chemicals</td> <td></td> </tr> <tr> <td>Provides accurate and precise measurements of biologically persistent chemicals</td> <td>Suspected chemicals of concern are less likely to be captured</td> <td></td> </tr> <tr> <td>Often targets known chemicals of toxicologic importance</td> <td>Time-intensive methods development and validation</td> <td></td> </tr> <tr> <td>Reference data exist for most chemicals</td> <td>Chemicals added for monitoring not always the most important from a toxicologic perspective</td> <td></td> </tr> <tr> <td>Targeted approach allows specific hypotheses of well-documented chemicals to be studied</td> <td>Analyses are expensive and time-consuming</td> <td></td> </tr> <tr> <td></td> <td>Few laboratories with expanded capabilities</td> <td></td> </tr> <tr> <td></td> <td>Multiple methods required for a large suite of chemicals</td> <td></td> </tr> <tr> <td></td> <td>Typically requires 500–2,000 μL of blood or other biospecimens for each chemical analyzed</td> <td></td> </tr> </tbody> </table> ### Appendix 3. Key advantages and disadvantages of exposomic approaches for determination of exposure. <table> <thead> <tr> <th>Exposomic approaches for determination of exposure</th> <th>Advantages</th> <th>Disadvantages</th> </tr> </thead> <tbody> <tr> <td>Agnostic approaches are encouraged for detection of emerging exposures of concern</td> <td>Agnostic approach can be problematic for grant funding</td> <td></td> </tr> <tr> <td>Techniques (and development of techniques) promote identification of unknown/emerging exposures of concern</td> <td>May not detect chemicals present at low levels</td> <td></td> </tr> <tr> <td>Links exogenous exposures to internal biochemical perturbations</td> <td>Cannot detect all analytes present in chemical space</td> <td></td> </tr> <tr> <td>A large number of features can be detected (&gt;10,000) for the cost of a single traditional biomonitoring analysis</td> <td>A reference or baseline value may not be possible to define</td> <td></td> </tr> <tr> <td>Includes biomolecular reaction products (e.g., protein adducts, DNA adducts) for which traditional biomonitoring measurements are often lacking or cumbersome</td> <td>Extensive bioinformatics required for data reduction/analysis</td> <td></td> </tr> <tr> <td>Requires a small amount of biologic specimen (~100 μL or less) for full-suite analysis</td> <td>Requires carefully collected and well-maintained biospecimens</td> <td></td> </tr> <tr> <td>Enables detection of “features” that are linked to exposure or disease for further confirmation</td> <td>Can only measure chemicals that are isolated in extraction process (e.g., acetonitrile extraction would not necessarily capture lipophilic chemicals)</td> <td></td> </tr> <tr> <td>Encourages techniques to capture short-lived chemicals</td> <td>Relies heavily upon library searching of spectra for annotation with standard confirmation coming later, which can be quite time-consuming and labor-intensive</td> <td></td> </tr> <tr> <td>Aims to measure biologically meaningful lifetime exposures, both exogenous and endogenous, of health relevance</td> <td>May be difficult to link measures to exposure source</td> <td></td> </tr> <tr> <td></td> <td>Includes lifetime exposures but does not place enough emphasis on defining and measuring windows of susceptibility (e.g., in utero) to accurately capture the most biologically important exposures</td> <td></td> </tr> </tbody> </table> new approaches, which would allow efficient integration of effective methods into research protocols. One approach would be to use samples from NHANES or from a similarly well-characterized data set as a “challenge” or “quality control” set for new and emerging technologies. Moreover, development of or participation in multi-lab proficiency testing programs will ensure harmonization of data across studies. **Recommendation 3:** Use existing resources and databases to obtain information on current exposures that may be important. Significant efforts have been made to expand databases such as the HMDB. ### Appendix 4. Biomonitoring resources. <table> <thead> <tr> <th>Category</th> <th>Resource/location</th> <th>Website</th> </tr> </thead> <tbody> <tr> <td></td> <td>LRN-C Laboratory Response Network for Chemical Threats Laboratory for Exposure Assessment and Development for Environmental Research (LEADER), Emory University</td> <td><a href="http://emergency.cdc.gov/lnm/chemical.asp">http://emergency.cdc.gov/lnm/chemical.asp</a> <a href="http://www.leaderlaboratory.org">www.leaderlaboratory.org</a></td> </tr> <tr> <td></td> <td>National Exposure Research Laboratory at U.S. Environmental Protection Agency (EPA)</td> <td><a href="http://www.epa.gov/nerl/">http://www.epa.gov/nerl/</a></td> </tr> <tr> <td></td> <td>Rocky Mountain Biomonitoring Consortium Projects</td> <td><a href="http://www.mrc2.umn.edu/">http://www.mrc2.umn.edu/</a></td> </tr> <tr> <td></td> <td>National Institute of Environmental Health Sciences (NIEHS) Children’s Environmental Health and Disease Prevention Research Centers</td> <td><a href="http://www.cdc.gov/biomonitoring/state_grants.html">http://www.cdc.gov/biomonitoring/state_grants.html</a></td> </tr> <tr> <td></td> <td>CHEAR: National Exposure Laboratory Network</td> <td><a href="http://www.cdc.gov/biomonitoring/state_grants.html">http://www.cdc.gov/biomonitoring/state_grants.html</a></td> </tr> <tr> <td></td> <td>CDC funded state biomonitoring grants in 2009 and 2014 (CA, NY, WA, MA, NH, NJ, VA, UT, AZ, CO, NM)</td> <td><a href="http://www.cdc.gov/biomonitoring/state_grants.html">http://www.cdc.gov/biomonitoring/state_grants.html</a></td> </tr> <tr> <td></td> <td>Rocky Mountain Biomonitoring Consortium Projects</td> <td><a href="http://www.cdc.gov/biomonitoring/state_grants.html">http://www.cdc.gov/biomonitoring/state_grants.html</a></td> </tr> <tr> <td></td> <td>National Institute of Environmental Health Sciences (NIEHS) Children’s Environmental Health and Disease Prevention Research Centers</td> <td><a href="http://www.cdc.gov/biomonitoring/state_grants.html">http://www.cdc.gov/biomonitoring/state_grants.html</a></td> </tr> <tr> <td></td> <td>National Exposure Research Laboratory at U.S. Environmental Protection Agency (EPA)</td> <td><a href="http://www.epa.gov/nerl/">http://www.epa.gov/nerl/</a></td> </tr> </tbody> </table> Biomonitoring in the era of the exposome Recommendation 4: Provide guidance for the use of existing databases and develop tools to allow searches across multiple databases. To facilitate researchers’ integrating exposomic approaches into their studies, resources regarding existing databases should be streamlined. Integration of existing databases such as the HMDB, LIPID MAPS Structure Database and METLIN or search options that can readily work across these resources would enhance their utility for exposome research (LIPID MAPS 2015; Smith et al. 2005; Wishart et al. 2009, 2013). Recommendation 5: Foster and facilitate discussion with people from different disciplines to discuss the reality of targeted and untargeted analytic capabilities. Discussions should focus around the development of semi-targeted or multiplexing strategies (Wei et al. 2010). Specific discussions should emphasize approaches for capturing short-lived chemicals while minimizing undue financial and participant burdens. Through generating discussion regarding established methods, researchers can have a structured dialogue concerning the utility of targeted, untargeted, and hybrid methods. Recommendation 6: Develop chemistries to enable the detection of low-abundance chemicals and to enable differentiation of endogenous molecules from exogenous molecules. Through methods such as multiplexing, interfering chemicals can be removed to allow detection of low-level environmental chemicals that are often difficult to detect because of higher-abundance endogenous chemicals from food, drugs, and normal metabolic processes (Rappaport et al. 2014). Investments in the development of semi-targeting or multiplexing strategies should be a high priority. Recommendation 7: Develop bioinformatics techniques to enhance detection of unknown chemicals using untargeted methods. With continued efforts such as ExpoCast, untargeted analysis can be combined with advanced bioinformatic techniques to help prioritize risk assessment, to determine which exposures often co-occur, and to establish markers of disease risk (Dennis et al. 2016; Johnson et al. 2015; Rager et al. 2016; Yu et al. 2013; Wambauh et al. 2013). Recommendation 8: Encourage development of pharmacokinetic models. Through building simulated human response models, researchers would be able to incorporate kinetic and dynamic variability to inform interpretation of biomonitoring data. Conclusions Measurable long-term improvements to human health are attainable through working towards a holistic understanding of environmental influences. In order to assess the exposome, traditional biomonitoring should be coupled with untargeted discovery of unknown chemicals of biological importance. It is critical to note that the advances described here, including those still in early stages of development, require commitment of scientific resources and energy to bring such approaches to fruition. Continued discussion and integration of approaches will be necessary to address the inherent complexity of the exposome. Broad characterization and understanding of internal exposures and their consequences are achievable under the exposome paradigm through combining emerging technologies and untargeted approaches with traditional biomonitoring techniques. References Kaufman AS, Zhou X, Reynolds MR, Kaufman NL, April 2017 Environmental Health Perspectives • VOLUME 125 • NUMBER 4 • April 2017 509