bluuebunny/crossref_metadata_2025 huggingface dataset:
The Institutional Features of the Prisoners of War Treaties
Authors: Morrow James D.
Published: July 2002

During the twentieth century states negotiated and ratified formal treaties on the treatment of prisoners of war (POWs). These treaties have created a system for the treatment of POWs with universal and detailed standards and decentralized enforcement. I explain the form of the POW system as a rational institutional response to four strategic problems the issue of POWs poses: monitoring under noise, individual as opposed to state violations, variation in preferred treatment of POWs, and raising a mass army. In response to these four problems, neutral parties help address the problem of monitoring the standards. The ratification process screens out some states that do not intend to live up to the standards. The two-level problem of state and individual violations is addressed by making states responsible for punishing the actions of their own soldiers. By protecting POWs, the treaties help states raise armies during wartime. The POW case supports many, but not all, of the Rational Design conjectures. In particular, it suggests other strategic logics to explain variation in the membership and centralization of international institutions.
Throwing Out the Baby with the Bath Water: A Comment on Green, Kim, and Yoon
Authors: Beck Nathaniel , Katz Jonathan N.
Published: July 2002

Donald P. Green, Soo Yeon Kim, and David H. Yoon argue that many findings in quantitative international relations that use the dyad-year design are flawed. In particular, they argue that the effect of democracy on both trade and conflict has been vastly overstated, that researchers have ignored unobserved heterogeneity between the various dyads, and that heterogeneity can be best modeled by “fixed effects,” that is, a model that includes a separate dummy for each dyad.

We argue that the use of fixed effects is almost always a bad idea for dyad-year data with a binary dependent variable like conflict. This is because conflict is a rare event, and the inclusion of fixed effects requires us to not analyze dyads that never conflict. Thus while the 90 percent of dyads that never conflict are more likely to be democratic, the use of fixed effects gives democracy no credit for the lack of conflict in these dyads. Green, Kim, and Yoon's fixed-effects logit can tell us little, if anything, about the pacific effects of democracy.

Their analysis of the impact of democracy on trade is also flawed. The inclusion of fixed effects almost always masks the impact of slowly changing independent variables; the democracy score is such a variable. Thus it is no surprise that the inclusion of dyadic dummy variables in their model completely masks the relationship between democracy and trade. We show that their preferred fixed-effects specification does not outperform a model with no effects (when that model is correctly specified in other ways). Thus there is no need to include the masking fixed effects, and so Green, Kim, and Yoon's findings do not overturn previous work that found that democracy enhanced trade.

We agree with Green, Kim, and Yoon that modeling heterogeneity in time-series cross-section data is important. We mention a number of alternatives to their fixed-effects approach, none of which would have the pernicious consequences of using dyadic dummies in their two reanalyses.
Dueling Realisms
Authors: Brooks Stephen G.
Published: July 2002

International relations scholars have tended to focus on realism's common features rather than exploring potential differences. Realists do share certain assumptions and are often treated as a group, but such a broad grouping obscures systematic divisions within realist theory. Recently, some analysts have argued that it is necessary to differentiate within realism. This article builds on this line of argument. The potential, and need, to divide realism on the basis of divergent assumptions has so far been overlooked. In this article I argue that realism can be split into two competing branches by revealing latent divisions regarding a series of assumptions about state behavior. The first branch is Kenneth Waltz's well-known neorealist theory; a second branch, termed here “postclassical realism,” has yet to be delineated as a major alternative but corresponds with a number of realist analyses that cohere with one another and are incompatible with Waltzian neorealism.
Who Are the “Masters of the Treaty”?: European Governments and the European Court of Justice
Authors: Alter Karen J.
Published: July 2002

To what extent can the European Court of Justice, an international court, make decisions that go against the interests of European Union member states? Neofunctionalist accounts imply that because the Court is a legal body it has vast political autonomy from the member states, whereas neorealist accounts imply that because member states can sanction the ECJ, the Court has no significant political autonomy. Neither theory can explain why the Court, which was once politically weak and did not stray far from the interests of European governments, now boldly rules against their interests. In explaining how the Court escaped member state control, this article develops a general hypothesis of the autonomy of the ECJ, focusing on how differing time horizons of political and judicial actors, support for the Court within the national judiciaries, and decision-making rules at the supranational level limit the member states' ability to control the Court.
Theory and Method in the Study of International Negotiation: A Rejoinder to Oran Young
Authors: Moravcsik Andrew
Published: July 2002

Under what conditions do officials in international organizations wield influence as informal political entrepreneurs? Two conditions, I argue in the article under discussion, must obtain: First, an asymmetry in the availability of information or ideas must impede national governments from negotiating Pareto-efficiently. High transaction costs, relative to gains, must induce a coordination failure. Actors able to provide the three essential entrepreneurial functions—initiatives, mediation, mobilization—must be scarce. Second, international officials must enjoy or be accorded privileged access to the information or ideas necessary to act as entrepreneurs and induce more efficient interstate bargains. Where either of these two conditions is absent, third-party entrepreneurial activities are likely to be redundant (because states, as stakeholders, would have greater means and incentives to act as entrepreneurs) or futile (because a consensual support among states would not be forthcoming anyway).
Expressive AI: A Hybrid Art and Science Practice
Authors: Mateas Michael
Published: July 2002

Expressive AI is a new interdiscipline of AI-based cultural production, combining art practice and AI-research practice. This article explores expressive AI by comparing it with other AI discourses, describing how it borrows notions of interpretation and authorship from both art and AI research practice and providing preliminary desiderata for the practice.
Evolutionary Cooperative Design Methodology: The Genetic Sculpture Park
Authors: Rowland Duncan , Biocca Frank
Published: July 2002

The Genetic Sculpture Park seeks to engage artists and observers in a creative dialogue and to empower novices in the creation of complex computer-graphic models. Each visitor to the park experiences a unique set of sculptural forms and takes part in a cooperative conversation with the computer to produce more aesthetically pleasing designs. Inspired by Darwin's theory of evolution, the project uses genetic algorithms to allow visitors to “breed” forms tailored to their individual sense of aesthetics. In this article, the authors recount investigations into evolutionary design methodologies (using shampoo bottles and three-dimensional head models) and describe their implementation in the Genetic Sculpture Park, an interactive Java/Virtual Reality Modeling Language (VRML) world.
Life Music: The Sonification of Proteins
Authors: Dunn John , Clark Mary Anne
Published: July 2002

An artist and a biologist have collaborated on the sonification of protein data to produce the audio compact disc Life Music. Here they describe the process by which this collaboration merges scientific knowledge and artistic expression to produce soundscapes from the basic building blocks of life. The soundscapes may be encountered as aesthetic experiences, as scientific inquiries or as both. The authors describe the rationale both for the artistic use of science and for the scientific use of art from the separate viewpoints of artist and scientist.
Imaginal, Semantic, and Surface-Level Processing of Concrete and Abstract Words: An Electrophysiological Investigation
Authors: West W. Caroline , Holcomb Phillip J.
Published: July 2002

Words representing concrete concepts are processed more quickly and efficiently than words representing abstract concepts. Concreteness effects have also been observed in studies using event-related brain potentials (ERPs). The aim of this study was to examine concrete and abstract words using both reaction time (RT) and ERP measurements to determine (1) at what point in the stream of cognitive processing concreteness effects emerge and (2) how different types of cognitive operations influence these concreteness effects. Three groups of subjects performed a sentence verification task in which the final word of each sentence was concrete or abstract. For each group the truthfulness judgment required either (1) image generation, (2) a semantic decision, or (3) evaluation of surface characteristics. Concrete and abstract words produced similar RTs and ERPs in the surface task, suggesting that postlexical semantic processing is necessary to elicit concreteness effects. In both the semantic and imagery tasks, RTs were shorter for concrete than for abstract words. This difference was greatest in the imagery task. Also, in both of these tasks concrete words elicited more negative ERPs than abstract words between 300 and 550 msec (N400). This effect was widespread across the scalp and may reflect activation in a linguistic semantic system common to both concrete and abstract words. ERPs were also more negative for concrete than abstract words between 550 and 800 msec. This effect was more frontally distributed and was most evident in the imagery task. We propose that this later anterior effect represents a distinct ERP component (N700) that is sensitive to the use of mental imagery. The N700 may reflect the access of specific characteristics of the imaged item or activation in a working memory system specific to mental imagery. These results also support the extended dual-coding hypothesis that superior associative connections and the use of mental imagery both contribute to processing advantages for concrete words over abstract words.
Performance on Indirect Measures of Race Evaluation Predicts Amygdala Activation
Authors: Phelps Elizabeth A. , O'Connor Kevin J. , Cunningham William A. , Funayama E. Sumie , Gatenby J. Christopher , Gore John C. , Banaji Mahzarin R.
Published: July 2002

We used fMRI to explore the neural substrates involved in the unconscious evaluation of Black and White social groups. Specifically, we focused on the amygdala, a subcortical structure known to play a role in emotional learning and evaluation. In Experiment 1, White American subjects observed faces of unfamiliar Black and White males. The strength of amygdala activation to Black-versus-White faces was correlated with two indirect (unconscious) measures of race evaluation (Implicit Association Test [IAT] and potentiated startle), but not with the direct (conscious) expression of race attitudes. In Experiment 2, these patterns were not obtained when the stimulus faces belonged to familiar and positively regarded Black and White individuals. Together, these results suggest that amygdala and behavioral responses to Black-versus-White faces in White subjects reflect cultural evaluations of social groups modified by individual experience.
Spike-Driven Synaptic Plasticity: Theory, Simulation, VLSI Implementation
Authors: Fusi Stefano , Annunziato Mario , Badoni Davide , Salamon Andrea , Amit Daniel J.
Published: July 2002

We present a model for spike-driven dynamics of a plastic synapse, suited for a VLSI implementation. The synaptic device behaves as a capacitor on short timescales and preserves the memory of two stable states (efficacies) on long timescales. The transitions (LTP/LTD) are stochastic because both the number and the distribution of neural spikes in any finite (stimulation) interval fluctuate, even at fixed pre- and postsynaptic spike rates. The dynamics of the single synapse is studied analytically by extending the solution to a classic problem in queuing theory (Takàcs process). The model of the synapse is implemented in a VLSI and consists of only 18 transistors. It is also directly simulated. The simulations indicate that LTP/LTD probabilities versus rates are robust to fluctuations of the electronic parameters in a wide range of rates. The solutions for these probabilities are in very good agreement with both the simulations and measurements. Moreover, the probabilities are readily manipulable by variations of the chip's parameters, even in ranges where they are very small. The tests of the electronic device cover the range from spontaneous activity (3–4 Hz) to stimulus-driven rates (50 Hz). Low transition probabilities can be maintained in all ranges, even though the intrinsic time constants of the device are short (∼ 100 ms).

Synaptic transitions are triggered by elevated presynaptic rates: for low presynaptic rates, there are essentially no transitions. The synaptic device can preserve its memory for years in the absence of stimulation. Stochasticity of learning is a result of the variability of interspike intervals; noise is a feature of the distributed dynamics of the network. The fact that the synapse is binary on long timescales solves the stability problem of synaptic efficacies in the absence of stimulation. Yet stochastic learning theory ensures that it does not affect the collective behavior of the network, if the transition probabilities are low and LTP is balanced against LTD.
An Autoassociative Neural Network Model of Paired-Associate Learning
Authors: Rizzuto Daniel S. , Kahana Michael J.
Published: July 2002

Hebbian heteroassociative learning is inherently asymmetric. Storing a forward association, from item A to item B, enables recall of B (given A), but does not permit recall of A (given B). Recurrent networks can solve this problem by associating A to B and B back to A. In these recurrent networks, the forward and backward associations can be differentially weighted to account for asymmetries in recall performance. In the special case of equal strength forward and backward weights, these recurrent networks can be modeled as a single autoassociative network where A and B are two parts of a single, stored pattern. We analyze a general, recurrent neural network model of associative memory and examine its ability to fit a rich set of experimental data on human associative learning. The model fits the data significantly better when the forward and backward storage strengths are highly correlated than when they are less correlated. This network-based analysis of associative learning supports the view that associations between symbolic elements are better conceptualized as a blending of two ideas into a single unit than as separately modifiable forward and backward associations linking representations in memory.
Derivation of the Visual Contrast Response Function by Maximizing Information Rate
Authors: Gottschalk Allan
Published: July 2002

A graph of neural output as a function of the logarithm of stimulus intensity often produces an S-shaped function, which is frequently modeled by the hyperbolic ratio equation. The response of neurons in early vision to stimuli of varying contrast is an important example of this. Here, the hyperbolic ratio equation with a response exponent of two is derived exactly by considering the balance between information rate and the neural costs of making that information available, where neural costs are a function of synaptic strength and spike rate. The maximal response and semisaturation constant of the neuron can be related to the stimulus ensemble and therefore shift accordingly to exhibit contrast gain control and normalization.
Analysis of Oscillations in a Reciprocally Inhibitory Network with Synaptic Depression
Authors: Taylor Adam L. , Cottrell Garrison W. , Kristan William B.
Published: July 2002

We present and analyze a model of a two-cell reciprocally inhibitory network that oscillates. The principal mechanism of oscillation is short-term synaptic depression. Using a simple model of depression and analyzing the system in certain limits, we can derive analytical expressions for various features of the oscillation, including the parameter regime in which stable oscillations occur, as well as the period and amplitude of these oscillations. These expressions are functions of three parameters: the time constant of depression, the synaptic strengths, and the amount of tonic excitation the cells receive. We compare our analytical results with the output of numerical simulations and obtain good agreement between the two. Based on our analysis, we conclude that the oscillations in our network are qualitatively different from those in networks that oscillate due to postinhibitory rebound, spike-frequency adaptation, or other intrinsic (rather than synaptic) adaptational mechanisms. In particular, our network can oscillate only via the synaptic escape mode of Skinner, Kopell, and Marder (1994).
A Population Study of Integrate-and-Fire-or-Burst Neurons
Authors: Casti A.R.R. , Omurtag A. , Sornborger A. , Kaplan E. , Knight B. , Victor J. , Sirovich L.
Published: July 2002

Any realistic model of the neuronal pathway from the retina to the visual cortex (V1) must account for the burstingbehavior of neurons in the lateral geniculate nucleus (LGN). A robust but minimal model, the integrate- and-fire-or-burst (IFB) model, has recently been proposed for individual LGN neurons. Based on this, we derive a dynamic population model and study a population of such LGN cells. This population model, the first simulation of its kind evolving in a two-dimensional phase space, is used to study the behavior of bursting populations in response to diverse stimulus conditions.
Complexity Issues in Natural Gradient Descent Method for Training Multilayer Perceptrons
Authors: Yang Howard Hua , Amari Shun-ichi
Published: July 2002

The natural gradient descent method is applied to train an n-m-1 multilayer perceptron. Based on an efficient scheme to represent the Fisher information matrix for an n-m-1 stochastic multilayer perceptron, a new algorithm is proposed to calculate the natural gradient without inverting the Fisher information matrix explicitly. When the input dimension n is much larger than the number of hidden neurons m, the time complexity of computing the natural gradient is O(n).
Neural Networks with Dynamic Synapses
Authors: Tsodyks Misha , Pawelzik Klaus , Markram Henry
Published: July 2002

Transmission across neocortical synapses depends on the frequency of presynaptic activity (Thomson & Deuchars, 1994). Interpyramidal synapses in layer V exhibit fast depression of synaptic transmission, while other types of synapses exhibit facilitation of transmission. To study the role of dynamic synapses in network computation, we propose a unified phenomenological model that allows computation of the postsynaptic current generated by both types of synapses when driven by an arbitrary pattern of action potential (AP) activity in a presynaptic population. Using this formalism, we analyze different regimes of synaptic transmission and demonstrate that dynamic synapses transmit different aspects of the presynaptic activity depending on the average presynaptic frequency. The model also allows for derivation of mean-field equations, which govern the activity of large, interconnected networks. We show that the dynamics of synaptic transmission results in complex sets of regular and irregular regimes of network activity.
Simulating Virtual Humans in Networked Virtual Environments
Authors: Pandzic Igor , Babski Christian , Capin Tolga , Lee WonSook , Magnenat-Thalmann Nadia , Musse Soraia Raupp , Moccozet Laurent , Seo Heywon , Thalmann Daniel
Published: July 2002

In the past decade, networked virtual environments (NVEs) have been an increasingly active area of research, with the first commercial systems emerging recently. Graphical and behavioral representation of users within such systems is a particularly important issue that has lagged in development behind other issues such as network architectures and space structuring. In this paper, we expose the importance of using virtual humans within these systems and provide a brief overview of several virtual humans technologies used in particular for simulation of crowds. As the main technical contribution, the paper presents the integration of these technologies with the COVEN-DIVE platform, the extension of the DIVE system developed within the COVEN project. In conjunction with this, we present our contributions through the COVEN project to the MPEG-4 standard concerning the representation of virtual humans.
Navigation System for the Blind: Auditory Display Modes and Guidance
Authors: Loomis Jack M. , Golledge Reginald G. , Klatzky Roberta L.
Published: July 2002

The research we are reporting here is part of our effort to develop a navigation system for the blind. Our long-term goal is to create a portable, self-contained system that will allow visually impaired individuals to travel through familiar and unfamiliar environments without the assistance of guides. The system, as it exists now, consists of the following functional components: (1) a module for determining the traveler's position and orientation in space, (2) a Geographic Information System comprising a detailed database of our test site and software for route planning and for obtaining information from the database, and (3) the user interface. The experiment reported here is concerned with one function of the navigation system: guiding the traveler along a predefined route. We evaluate guidance performance as a function of four different display modes: one involving spatialized sound from a virtual acoustic display, and three involving verbal commands issued by a synthetic speech display. The virtual display mode fared best in terms of both guidance performance and user preferences.
A Model for Understanding How Virtual Reality Aids Complex Conceptual Learning
Authors: Salzman Marilyn C. , Dede Chris , Loftin R. Bowen , Chen Jim
Published: July 2002

Designers and evaluators of immersive virtual reality systems have many ideas concerning how virtual reality can facilitate learning. However, we have little information concerning which of virtual reality's features provide the most leverage for enhancing understanding or how to customize those affordances for different learning environments. In part, this reflects the truly complex nature of learning. Features of a learning environment do not act in isolation; other factors such as the concepts or skills to be learned, individual characteristics, the learning experience, and the interaction experience all play a role in shaping the learning process and its outcomes. Through Project Science Space, we have been trying to identify, use, and evaluate immersive virtual reality's affordances as a means to facilitate the mastery of complex, abstract concepts. In doing so, we are beginning to understand the interplay between virtual reality's features and other important factors in shaping the learning process and learning outcomes for this type of material. In this paper, we present a general model that describes how we think these factors work together and discuss some of the lessons we are learning about virtual reality's affordances in the context of this model for complex conceptual learning.
A Theoretical Model of Wayfinding in Virtual Environments: Proposed Strategies for Navigational Aiding
Authors: Chen Jui Lin , Stanney Kay M.
Published: July 2002

This paper proposes a theoretical model of wayfinding that can be used to guide the design of navigational aiding in virtual environments. Based on an evaluation of wayfinding studies in natural environments, this model divides the wayfinding process into three main subprocesses: cognitive mapping, wayfinding plan development, and physical movement or navigation through an environment. While this general subdivision has been proposed before, the current model further delineates the wayfinding process, including the distinct influences of spatial information, spatial orientation, and spatial knowledge. The influences of experience, abilities, search strategies, motivation, and environmental layout on the wayfinding process are also considered. With this specification of the wayfinding process, a taxonomy of navigational tools is then proposed that can be used to systematically aid the specified wayfinding subprocesses. If effectively applied to the design of a virtual environment, the use of such tools should lead to reduced disorientation and enhanced wayfinding in large-scale virtual spaces. It is also suggested that, in some cases, this enhanced wayfinding performance may be at the expense of the acquisition of an accurate cognitive map of the virtual environment being traversed.
Greenhouse Gas Profile of a Plastic Material Derived from a Genetically Modified Plant
Authors: Kurdikar Devdatt , Fournet Laurence , Slater Steven C. , Paster Mark , Gruys Kenneth J. , Gerngross Tillman U. , Coulon Remi
Published: July 2002

Abstract: This article reports an assessment of the global warming potential associated with the life cycle of a biopolymer (poly(hydroxyalkanoate) or PHA) produced in genetically engineered corn developed by Monsanto. The grain corn is harvested in a conventional manner, and the polymer is extracted from the corn stover (i.e., residues such as stalks, leaves and cobs), which would be otherwise left on the field. While corn farming was assessed based on current practice, four different hypothetical PHA production scenarios were tested for the extraction process. Each scenario differed in the energy source used for polymer extraction and compounding, and the results were compared to polyethylene (PE). The first scenario involved burning of the residual biomass (primarily cellulose) remaining after the polymer was extracted from the stover. In the three other scenarios, the use of conventional energy sources of coal, oil, and natural gas were investigated. This study indicates that an integrated system, wherein biomass energy from corn stover provides energy for polymer processing, would result in a better greenhouse gas profile for PHA than for PE. However, plant‐based PHA production using fossil fuel sources provides no greenhouse gas advantage over PE, in fact scoring worse than PE. These results are based on a “cradle‐to‐pellet” modeling as the PHA end‐of‐life was not quantitatively studied due to complex issues surrounding the actual fate of postconsumer PHA.
Planning Biodegradable Waste Management in Stockholm
Authors: Björklund Anna , Bjuggren Charlotte , Dalemo Magnus , Sonesson Ulf
Published: July 2002

The environmental impact of the management of biodegradable waste in Stockholm, based mainly on incineration and landfilling, was compared to systems with significant nutrient recycling; large‐scale composting, anaerobic digestion, and separate collection and utilization of urine. The systems' emissions, residual products, energy turnover, and resource consumption were evaluated from a life‐cycle perspective, using a computerized model, ORWARE (ORganic WAste REsearch model).

Transportation was of relatively low importance to overall environmental impact, even at high rates of nutrient recycling. This is remarkable considering the geographical setting of Stockholm, with high population density and little nearby farmland. Ancillary systems, such as generation of electricity and district heating, were crucial for the overall outcome.

Increased recycling of nutrients in solid biodegradable waste in Stockholm can reduce net environmental impact, whereas separation of human urine to be spread as fertilizer cannot yet be introduced without increased acidification. Increased nutrient recycling from solid biodegradable waste inevitably increases spreading of metals on arable land. Urine is by far the least contaminated residual product. Spreading of all other residuals would be limited by their metal content.
PREDATOR HANDLING FAILURES OF LATERAL PLATE MORPHS IN GASTEROSTEUS ACULEATUS: FUNCTIONAL IMPLICATIONS FOR THE ANCESTRAL PLATE CONDITION
Authors: Reimchen T.E.
Published: July 2002

The completely plated morph in the threespine stickleback (Gasterosteus aculeatus) is considered to be the ancestral plate condition and is the predominant morph inhabiting marine waters and numerous northern freshwaters. Evolutionary aspects of this distribution have been widely addressed yet functional mechanisms remain obscure. Experiments described here using the common piscivore (Oncorhynchus clarki) show that the posterior plates of G. aculeatus interfere with the swallowing abilities of the piscivore, possibly by disrupting pharyngeal jaw retraction, and this leads to increased escape opportunities of the stickleback. The advantage of the completely plated condition is most expressed at higher ratios of prey diameter to predator mouth diameter and appears to have a defensive effect comparable to that of dorsal and pelvic spines. This attribute, combined with the physical protection that plates offer against puncturing, would be particularly beneficial where there is high probability of capture by toothed predators. Such a selection regime appears to characterize the predominantly limnetic and pelagic habitats where marine stickleback are found and may account for the wide geographical distribution of the completely plated morph and its persistence from the Miocene.
SPLIT-CLUTCH IVF: A TECHNIQUE TO EXAMINE INDIRECT FITNESS CONSEQUENCES OF MATE PREFERENCES IN STICKLEBACKS
Authors: Barber Iain , Arnott Stephen
Published: July 2002

Although laboratory mate choice experiments and field studies often reveal certain traits of male three-spined sticklebacks (as well as other model species) to be attractive to mate searching females, evidence that mating with males possessing such traits improves offspring survival and performance is scarce. In particular, there is a lack of unambiguous data linking preferred male traits with inherited genetic 'viability', which are essential for 'good genes' models of sexual selection. In this paper, we provide a protocol for performing half-sibling crosses in three-spined sticklebacks using a split-clutch in vitro fertilisation (SC-IVF) technique. This approach controls for variable maternal investment and standardises parental care — two confounding variables that frequently distort the relationship between sire trait and offspring performance — allowing the detection of offspring viability characteristics linked to specific sire traits such as sexual coloration, body size or condition.
The influence of root diffusate, host age and water regimes on hatching of the root-knot nematode, Meloidogyne triticoryzae
Authors: Gaur Hari , Beane Jack , Perry Roland
Published: July 2002

The root-knot nematode, Meloidogyne triticoryzae, produces three kinds of
unhatched second stage juveniles (J2): i) those that hatch freely in water,
ii) those that require stimulus from rice root diffusate (RRD), and iii)
those that do not hatch even in the presence of RRD. The proportion of these
three types varies with generation, with the final generation produced on
senescing plants having a large proportion of unhatched J2 of the third
type, which is likely to equate with diapause. Dilution of RRD reduced its
hatching activity and there is no evidence of the presence of inhibitors in
the diffusate. The hatching response of M. triticoryzae may be modified
additionally by the growing conditions: submergence of infected plants may
have delayed hatch, possibly by causing anoxybiosis in unhatched J2, and
thereby delayed the appearance of the second and third generations of the
nematodes. Le nématode Meloidogyne triticoryzae produit trois types de
juvéniles de 2ème stade (J2) non encore éclos: i) ceux qui éclosent
d’eux-même dans l’eau; ii) ceux qui requièrent le stimulus produit par le
diffusat radiculaire de riz (RRD); enfin iii) ceux qui n’éclosent pas même
en présence de RRD. La proportion de ces trois types varie avec la
génération du nématode, la dernière génération, produite sur un hôte
sénescent, contenant une grande proportion de J2 non éclos de type 3, ce
fait représentant l’équivalent d’une diapause. La dilution du RRD diminue
l’éclosion et aucune évidence d’inhibiteurs n’a été relevée dans le
diffusat. Chez M. triticoryzae l’éclosion peut de plus être modifiée par les
conditions de croissance de l’hôte; ainsi la submersion des plants infestés
peut retarder l’éclosion, l’anoxybiose ainsi induite affectant
vraisemblablement les J2 non éclos et retardant de ce fait l’apparition des
deuxième et troisième générations du nématode.
Hemicriconemoides macrodorus n. sp. with observations on two other species of the genus (Nematoda: Criconematidae)
Authors: Castillo Pablo , Troccoli Alberto , Vovlas Nicola
Published: July 2002

Hemicriconemoides macrodorus n. sp. is described and illustrated from a bisexual population collected in a natural habitat at Santa Elena, Jaén, southern Spain. The new species falls into the 'group 2', based on lip patterns (Decraemer & Geraert, 1992), which contains 13 other species characterised by a cephalic region with an offset, raised, narrower oral disc, followed by broader head annuli. The main distinctive characters of the new species are: lip region truncate, very long stylet (90-100 μ m), long body 548-750 μ m, R = 127-148, conical tail, VL/VB = 1.0-1.5, spined juvenile cuticular ornamentation (multispined scales, indented at their edges) arranged in ten alternate rows, and male lateral field with four incisures. Morphometric data, illustrations and brief descriptions are presented for an Italian population of H. ortonwilliamsi Ye & Siddiqi, 1994, while, for the first time, morphometric data and illustrations are given for the male and the juvenile of H. alexis Vovlas, 1980. Hemicriconemoides macrodorus n. sp. et observations sur deux autres espèces du genre (Nematoda: Criconematidae) - Hemicriconemoides macrodorus n. sp. est décrit et figuré d'une population bisexuelle collectée dans un habitat naturel à Santa Elena, Jaén, le Sud d'Espagne. La nouvelle espèce appartient au ''groupe 2'' sur la base de la morphologie labiale (Decraemer & Geraert, 1992), groupe comptant 13 autres espèces caractérisées par une région céphalique avec un disque labial séparé du reste du corps, proéminent et rétréci, suivi des anneaux céphaliques plus larges. Les principaux caractères distinctifs de la nouvelle espèce sont: région labiale tronquée, très long stylet (90-100 μ m), corps long 548-750 μ m, R = 127-148, queue conique, VL/VB = 1.0- 1.5, ornementations cuticulaires des juvéniles avec épines (écailles avec plusieurs épines, indentées sur les côtés) arrangées en dix rangées alternées, et champ latéral du mâle comportant quatre incisures. Des données morphométriques, des illustrations et de brèves descriptions sont présentées pour une population italienne de H. ortonwilliamsi Ye & Siddiqi, 1994, alors que, pour la première fois, des données morphométriques et des illustrations sont produites pour le mâle et les juvéniles de H. alexis Vovlas, 1980.
NIETSCHE'S CONTRIBUTION TO A PHENOMENOLOGY OF INTOXICATION
Authors: Sikka Sonia
Published: July 2002

Through a reading of Nietzsche's texts, primarily of Thus Spoke Zarathustra, this article develops a phenomenological description of the variety of intoxication exemplified in conditions of drunkenness, or in states of emotional excess. It treats Thus Spoke Zarathustra as a literary expression of such intoxication, arguing against attempts to find a coherent narrative structure and clear authorial voice behind this text's apparent disorder. Having isolated the intoxicated characteristics of Thus Spoke Zarathustra - its hyperbolic rhetoric and emotions, its lack of balance, its injustice, its shifting and conflicting moods, and its self-contradictions - I then offer an interpretation of the work, and by extension of intoxication itself, in terms of Nietzsche's model of the self as a dynamic multiplicity of forces. At the same time, I argue for a multiple and dynamic conception of personality in general.
Diagenesis of trioctahedral clays in a Miocene to Pleistocene sedimentary–magmatic sequence in the Dead Sea Rift, Israel
Authors: Sandler A. , Nathan Y. , Eshet Y. , Raab M.
Published: July 2002

The diagenetic evolution of clay minerals in a 4249 m sedimentary-magmatic sequence of the Zemah-1 drillhole in the Dead Sea Rift, Israel, was studied, mainly by X-ray diffraction (XRD). The parallel maturation of the organic matter was estimated by the thermal alteration index (TAI) method. Both parameters follow a progressive diagenesis with depth. The original clays, now encountered only at shallow depths, were dioctahedral, and mostly detrital. They transformed into Mg-rich trioctahedral clays starting with a saponite-dominated assemblage, followed by a saponite, ordered chlorite-smectite (C-S), and chlorite assemblage, and finally by a saponite, corrensite, chlorite and talc assemblage. Significant mineralogical composition gaps occur between saponite to corrensite and corrensite to chlorite. Short-range variations within the most evolved assemblage are controlled by bulk-rock composition. Depths of first occurrence and disappearance of minerals indicate a much higher geothermal gradient in the past whereas the TAI values suggest an even higher palaeogradient of ∼708C km–1.
Effect of grinding and water vapour on the particle size of kaolinite and pyrophyllite
Authors: Stepkowska E. T. , Pérez–Rodríguez J. L. , Jiménez de Haro M. C. , Sánchez–Soto P. J. , Maqueda C.
Published: July 2002

The increase in specific surface of kaolinite (K) and pyrophyllite (P) induced by dry grinding in an oscillatory mill, proceeded during storage in water vapour. The average particle thickness, δ, changed from 42 nm (K) and 66 nm (P) in the original materials to 12 nm (K) and 20 nm (P) after water sorption (20 days at relative humidity RH = 1.0, at room temperature and pressure) and to similar values of 13 nm (K) and 16 nm (P) after grinding for 10 min (in agreement with some published data). The action of water molecules on ground clays (at the conditions indicated) resulted in a further decrease in δ. In pyrophyllite, prolonged grinding (30 min) and prolonged action of water molecules (36 days) caused a particle collapse. After pre-storing at RH = 0.5 the successive decrease in δ at RH = 1.0 was smaller.
Phase transitions in tridymite studied using ‘Rigid Unit Mode’ theory, Reverse Monte Carlo methods and molecular dynamics simulations
Authors: Dove M. T. , Pryde A. K. A. , Keen D. A.
Published: July 2002

The phase transitions in tridymite and the nature of the high-temperature phase are investigated using a combination of Rigid Unit Mode theory, neutron total scattering measurements analysed using the Reverse Monte Carlo method, and molecular dynamics simulations. The unusually large number of phase transitions in tridymite can be explained within the Rigid Unit Mode theory. The Rigid Unit Mode theory also gives an interpretation of the disordered high-temperature phase as revealed by the neutron scattering data and the molecular dynamics simulations. There is a close correspondence between the structure of the disordered high-temperature phase of tridymite and that of β-cristobalite.
Mineralogical aspects of cement in radioactive waste disposal
Authors: Glasser F. P.
Published: July 2002

Some of the physical, chemical and mineralogical characteristics of Portland cement and related materials relevant to nuclear waste immobilization are defined. The ability to condition and maintain a high aqueous pH is undoubtedly the most important factor: it precipitates many species as hydrous oxides or hydroxides. However, in the longer term, many species – cationic as well as anionic – react with one or more cement components forming solubility-limiting phases. Progress on characterization of these phases is outlined. Many of the host phases have natural equivalents and this gives comfort in respect of their likely persistence over geological time. The emerging picture of immobilization in cement suggests that cement compositions can be tailored in terms of pH, Eh and internal chemistry so as to maximize immobilization potential. Nickel, uranium and chromium and chloride are used as examples.
Spontaneous strain in synthetic titanite, CaTiOSiO4
Authors: Malcherek T.
Published: July 2002

Lattice parameters of synthetic titanite powder, CaTiOSiO4, have been determined between room temperature and 1023 K. Only the e11 and e13 components contribute significantly to the strain tensor associated with the antiferroelectric-paraelectric phase transition at Tc = 487 K. A finite strain component e13 is observed in the paraelectric phase for 487 K < T < 825 K. The disappearance of this shear strain marks the isosymmetric transition near 825 K. The temperature evolution of the volume strain and of e11 is proportional to the squared order parameter observed in single-crystal diffraction experiments. The magnitude of the volume strain is sufficiently large to relate the observed near tricritical behaviour of the antiferroelectric-paraelectric phase transition to strain coupling.
Formation of the Denchai gem sapphires, northern Thailand: evidence from mineral chemistry and fluid/melt inclusion characteristics
Authors: Limtrakun P. , Zaw Khin , Ryan C. G. , Mernagh T. P.
Published: July 2002

The Denchai gem sapphire deposits in Phrae Province, northern Thailand are closely associated with late Cenozoic alkaline basaltic rocks. The sapphires occur in alluvial placer deposits in palaeo-channels at shallow depths. Electron microprobe analysis of minor and trace element contents (Fe, Ti, Cr, Ga and V) of the sapphires indicate the following oxide abundances: Fe2O3 (0.32–1.98 wt.%), TiO2 (0.01–0.23 wt.%), Cr2O3 (<0.01 wt.%), Ga2O3 (0.01–0.03 wt.%) and V2O5 (<0.03 wt.%). Optical studies of sapphires revealed three types of primary fluid/melt inclusions. CO2-rich inclusions (Type I) contain three phases (LH2O + LCO2 + V) with the vapour phase comprising <10–15 vol.%. The presence of CO2 was confirmed by microthermometry and laser Raman analysis. Polyphase inclusions (Type II) (vapour + liquid + solid) contain a fluid bubble (20–30 vol.%), an aqueous phase (10–15 vol.%) and several solid phases. Silicate-melt inclusions (Type III) comprise vapour bubbles, silicate glass and solid phases. Proton-induced X-ray emission (PIXE) analysis revealed high concentrations of K (~;4 wt.%) as well as Ca (~;0.5 wt.%), Ti (~;1 wt.%), Fe (~;2 wt.%), Mn (~;0.1 wt.%), V (<0.03 wt.%), Rb (~;70 ppm) and Zr (~;200 ppm) in the silicate glass. The Ga2O3 abundances and Cr2O3/Ga2O3 values (<1) of the sapphires favour their formation by magmatic processes. The presence of CO2-rich fluids and high K concentrations in the silicate melt inclusions link the origin of the Denchai gem sapphires to CO2-rich alkaline magmatism.
Neutron diffraction at simultaneous high temperatures and pressures, with measurement of temperature by neutron radiography
Authors: Le Godec Y. , Dove M. T. , Francis D. J. , Kohn S. C. , Marshall W. G. , Pawley A. R. , Price G. D. , Redfern S. A. T. , Rhodes N. , Ross N. L. , Schofield P. F. , Schooneveld E. , Syfosse G. , Tucker M. G. , Welch M. D.
Published: July 2002

The commissioning and operation of apparatus for neutron diffraction at simultaneous high temperatures and pressures is reported. The basic design is based on the Paris-Edinburgh cell using opposed anvils, with internal heating. Temperature is measured using neutron radiography. The apparatus has been shown in both on-line and off-line tests to operate to a pressure of 7 GPa and temperature of 1700°C. The apparatus has been used in a neutron diffraction study of the crystal structure of deuterated brucite, and results for 520°C and 5.15 GPa are presented. The diffraction data that can be obtained from the apparatus are of comparable quality to previous high-pressure studies at ambient temperatures, and are clearly good enough for Rietveld refinement analysis to give structural data of reasonable quality.
Raman microscopic study of the Li amphibole holmquistite, from the Martin Marietta Quarry, Bessemer City, NC, USA
Authors: Kloprogge J. T. , Case M. H. , Frost R. L.
Published: July 2002

The Raman spectrum of holmquistite, a Li-containing orthorhombic amphibole from Bessemer City, USA has been measured. The OH-stretching region is characterized by bands at 3661, 3646, 3634 and 3614 cm−1 assigned to 3 Mg–OH, 2 Mg + Fe2+–OH, Mg + 2Fe2+–OH and 3 Fe2+–OH, respectively. These Mg and Fe2+ cations are located at the M1 and M3 sites and have a Fe2+/(Fe2+ + Mg) ratio of 0.35. The 960–1110 cm−1 region represents the antisymmetric Si–O–Si and O–Si–O stretching vibrations. For holmquistite, strong bands are observed around 1022 and 1085 cm−1 with a shoulder at 1127 cm−1 and minor bands at 1045 and 1102 cm−1. In the region 650–800 cm−1 bands are observed at 679, 753 and 791 cm−1 with a minor band around 694 cm−1 attributed to the symmetrical Si–O–Si and Si–O vibrations. The region below 625 cm−1 is characterized by 14 vibrations related to the deformation modes of the silicate double chain and vibrations involving Mg, Fe, Al and Li in the various M sites. The 502 cm−1 band is a Li–O deformation mode while the 456, 551 and 565 cm−1 bands are Al–O deformation modes.
The exhumation history of orogenic belts from40Ar/39Ar ages of detrital micas
Authors: Stuart F. M.
Published: July 2002

The exhumation history of mountain belts can be derived from radiometric dating of detrital mineral grains in proximal and distal post- and synorogenic sediments. The application of single-crystal dating techniques avoids the averaging effect that characterizes multi-grain and whole-rock techniques and allows the identification of populations of grains with distinct thermal histories. Of the major single crystal dating methods available,40Ar/39Ar dating of detrital K-bearing minerals, in particular white mica, is perhaps the most versatile and widely applied technique. For a closure temperature of Ar of 350–400°C, muscovite40Ar/39Ar ages record the time a rock mass passed through 8–10 km beneath actively eroding mountain belts. Detrital muscovit ages eroded from orogenic mountain belts have been used extensively to identify the provenance of sediments from source regions with distinct thermal histories, determine the history and rate of exhumation of the source region, and provide an upper limit on the sediment age. Here I review the principles of40Ar/39Ar dating of detrital muscovite and illustrate the method with examples showing how the provenance and the thermal history of sediment source regions derived from such studies can be used to constrain the exhumation and tectonic history of orogenic belts.