bluuebunny/crossref_metadata_2025 huggingface dataset:
War Is in the Error Term
Authors: Gartzke Erik
Published: July 2002

At least since Thucydides, students of international relations have sought rational explanations for the advent of war. Rationalist explanations assume purposive action; states are said to make reasoned decisions about the use of force. Although rationalist explanations have proven persuasive, durable, and offer the basis for cumulative theorizing, they also imply substantial limits on what we can know about war. I show that the most general rationalist explanation for war also dictates that the onset of war is theoretically indeterminate. We cannot predict in individual cases whether states will go to war, because war is typically the consequence of variables that are unobservable ex ante, both to us as researchers and to the participants. Thinking probabilistically continues to offer the opportunity to assess international conflict empirically. However, the realization that uncertainty is necessary theoretically to motivate war is much different from recognizing that the empirical world contains a stochastic element. Accepting uncertainty as a necessary condition of war implies that all other variables—however detailed the explanation—serve to eliminate gradations of irrelevant alternatives. We can progressively refine our ability to distinguish states that may use force from those that are likely to remain at peace, but anticipating wars from a pool of states that appear willing to fight will remain problematic. For example, we may achieve considerable success in anticipating crises, but our ability to predict which crises will become wars will probably prove little better than the naive predictions of random chance. The need for uncertainty to account for war means that the same conditions thought to account for war must also exist among states not destined to fight. Otherwise, states themselves will differentiate between opponents in a way that either removes the motives for war or restores uncertainty. It has long been accepted that social processes possess an element of uncertainty, but the centrality of uncertainty to rationalist explanations for war means that the advent of war is itself stochastic. War is literally in the “error term.”
Space, Property, and Propriety in Urban England
Authors: Harding Vanessa
Published: July 2002

The public space in medieval towns and cities was shaped and influenced by the private spaces that surrounded it. The private was, like the public, a complex domain; many interests coexisted there. The pressures of population gowth and commercial development fragmented individual holdings and created overlapping layers of claims to particular spaces. Neighbors' interests also impinged; the enjoyment of the private was far from exclusive. Elaborate codes of property rights and legal procedures evolved as a fundamental part of urban custom. When the property market declined in the later Middle Ages, however, practices changed, and new ways of defining and describing private property emerged.
Restyling “Wisdom,” Remodeling the Nobility, and Caricaturing the Peasant: Urban Literature in the Late Medieval Low Countries
Authors: Pleij Herman
Published: July 2002

The literary works generated by and within the new urban spaces of the late medieval Low Counties were, in large part, defined by the relationships between cities and their spatial opponents—the landed nobility and the lower classes. The new fiction transformed aristocratic heroes of courtly literature into practical businessmen and ridiculed peasants to celebrate the values of urban life. It also advanced a new concept of wisdom that, though rooted in classical and medieval philosophies, proclaimed the supreme values of urban individualism, pragmatism, and self-control.
Children's Passive: A View from the By-Phrase
Authors: Fox Danny , Grodzinsky Yosef
Published: July 2002

This article argues that children's difficulty with passive constructions is related to properties of the by-phrase. Specifically, we argue that children are in full control of all aspects of the passive construction except for the ability to transmit the external θ-role of the predicate to the by-phrase; we thus reject Borer and Wexler's (1987) claim regarding the maturation of A-chains. Our conclusion is dictated by the results of an experiment we conducted, and supported by data already present in the literature.
The Role of Segmentation in Phonological Processing: An fMRI Investigation
Authors: Burton Martha W. , Small Steven L. , Blumstein Sheila E.
Published: July 2002

Phonological processes map sound information onto higher levels of language processing and provide the mechanisms by which verbal information can be temporarily stored in working memory. Despite a strong convergence of data suggesting both left lateralization and distributed encoding in the anterior and posterior perisylvian language areas, the nature and brain encoding of phonological subprocesses remain ambiguous. The present study used functional magnetic resonance imaging (fMRT) to investigate the conditions under which anterior (lateral frontal) areas are activated during speech-discrimination tasks that differ in segmental processing demands. In two experiments, subjects performed “same/ different” judgments on the first sound of pairs of words. In the first experiment, the speech stimuli did not require overt segmentation of the initial consonant from the rest of the word, since the “different” pairs only varied in the phonetic voicing of the initial consonant (e.g., dip-tip). In the second experiment, the speech stimuli required segmentation since “different” pairs both varied in initial consonant voicing and contained different vowels and final consonants (e.g., dip-ten). These speech conditions were compared to a tone-discrimination control condition. Behavioral data showed that subjects were highly accurate in both experiments, but revealed different patterns of reaction-time latencies between the two experiments. The imaging data indicated that whereas both speech conditions showed superior temporal activation when compared to tone discrimination, only the second experiment showed consistent evidence of frontal activity. Taken together, the results of Experiments 1 and 2 suggest that phonological processing per se does not necessarily recruit frontal areas. We postulate that frontal activation is a product of segmentation processes in speech perception, or alternatively, working memory demands required for such processing.
Visualization and Measurement of the Cortical Surface
Authors: Wandell Brian A. , Chial Suelika , Backus Benjamin T.
Published: July 2002

Much of the human cortical surface is obscured from view by the complex pattern of folds, making the spatial relationship between different surface locations hard to interpret. Methods for viewing large portions of the brain's surface in a single flattened representation are described. The flattened representation preserves several key spatial relationships between regions on the cortical surface. The principles used in the implementations and evaluations of these implementations using artificial test surfaces are provided. Results of applying the methods to structural magnetic resonance measurements of the human brain are also shown. The implementation details are available in the source code, which is freely available on the Internet.
Abnormal Functional Activation During a Simple Word Repetition Task: A PET Study of Adult Dyslexics
Authors: McCrory Eamon , Frith Uta , Brunswick Nicola , Price Cathy
Published: July 2002

Eight dyslexic subjects, impaired on a range of tasks requiring phonological processing, were matched for age and general ability with six control subjects. Participants were scanned using positron emission tomography (PET) during three conditions: repeating real words, repeating pseudowords, and rest. In both groups, speech repetition relative to rest elicited widespread bilateral activation in areas associated with auditory processing of speech; there were no significant differences between words and pseudowords. However, irrespective of word type, the dyslexic group showed less activation than the control group in the right superior temporal and right post-central gyri and also in the left cerebellum. Notably, the right anterior superior temporal cortex (Brodmann's area 22 [BA 22]) was less activated in each of the eight dyslexic subjects, compared to each of the six control subjects. This deficit appears to be specific to auditory repetition as it was not detected in a previous study of reading which used the same sets of stimuli (Brunswick, N., McCrory, E., Price, C., Frith, C.D., & Frith, U. [1999]. Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz? Brain, 122, 1901-1917). This implies that the observed neural manifestation of developmental dyslexia is task-specific (i.e., functional rather than structural). Other studies of normal subjects indicate that attending to the phonetic structure of speech leads to a decrease in right-hemisphere processing. Lower right hemisphere activation in the dyslexic group may therefore indicate less processing of non-phonetic aspects of speech, allowing greater salience to be accorded to phonological aspects of attended speech.
Visual Imagery in Hemianopic Patients
Authors: Gbadamosi Joystone , Zangemeister Wolfgang H.
Published: July 2002

In this article we report some findings about visual imagery in patients with stable homonymous hemianopia compared to healthy control subjects. These findings were obtained by analyzing the gaze control through recording of eye movements in different phases of viewing and imagery. We used six different visual stimuli for the consecutive viewing and imagery phases. With infrared oculography, we recorded eye movements during this presentation phase and in three subsequent imagery phases in absence of the stimulus. Analyzing the basic parameters of the gaze sequences (known as “scanpaths”), we discovered distinct characteristics of the “viewing scanpaths” and the “imagery scanpaths” in both groups, which suggests a reduced extent of the image within the cognitive representation. We applied different similarity measures (string/vector string editing, Markov analysis). We found a “progressive consistency of imagery,” shown through raising similarity values for the comparison of the late imagery scanpaths. This result suggests a strong top-down component in picture exploration: In both groups, healthy subjects and hemianopic patients, a mental model of the viewed picture must evolve very soon and substantially determine the eye movements. As our hemianopic patients showed analogous results to the normal subjects, we conclude that these patients are well adjusted to their deficit and, despite their perceptual defect, have a preserved cognitive representation, which follows the same top-down vision strategies in the process of visual imagery.
Visual Categorization and Object Representation in Monkeys and Humans
Authors: Sigala N. , Gabbiani F. , Logothetis N. K.
Published: July 2002

We investigated the influence of a categorization task on the extraction and representation of perceptual features in humans and monkeys. The use of parameterized stimuli (schematic faces and fish) with fixed diagnostic features in combination with a similarity-rating task allowed us to demonstrate perceptual sensitization to the diagnostic dimensions of the categorization task for the monkeys. Moreover, our results reveal important similarities between human and monkey visual subordinate categorization strategies. Neither the humans nor the monkeys compared the new stimuli to class prototypes or based their decisions on conditional probabilities along stimulus dimensions. Instead, they classified each object according to its similarity to familiar members of the alternative categories, or with respect to its position to a linear boundary between the learned categories.
Testing the Efficiency and Independence of Attentional Networks
Authors: Fan Jin , McCandliss Bruce D. , Sommer Tobias , Raz Amir , Posner Michael I.
Published: July 2002

In recent years, three attentional networks have been defined in anatomical and functional terms. These functions involve alerting, orienting, and executive attention. Reaction time measures can be used to quantify the processing efficiency within each of these three networks. The Attention Network Test (ANT) is designed to evaluate alerting, orienting, and executive attention within a single 30-min testing session that can be easily performed by children, patients, and monkeys. A study with 40 normal adult subjects indicates that the ANT produces reliable single subject estimates of alerting, orienting, and executive function, and further suggests that the efficiencies of these three networks are uncorrelated. There are, however, some interactions in which alerting and orienting can modulate the degree of interference from flankers. This procedure may prove to be convenient and useful in evaluating attentional abnormalities associated with cases of brain injury, stroke, schizophrenia, and attention-deficit disorder. The ANT may also serve as an activation task for neuroimaging studies and as a phenotype for the study of the influence of genes on attentional networks.
Deactivation of Sensory-Specific Cortex by Cross-Modal Stimuli
Authors: Laurienti Paul J. , Burdette Jonathan H. , Wallace Mark T. , Yen Yi-Fen , Field Aaron S. , Stein Barry E.
Published: July 2002

Visual and auditory cortices traditionally have been considered to be “modality-specific.” Thus, their activity has been thought to be unchanged by information in other sensory modalities. However, using functional magnetic resonance imaging (fMRI), the present experiments revealed that ongoing activity in the visual cortex could be modulated by auditory information and ongoing activity in the auditory cortex could be modulated by visual information. In both cases, this cross-modal modulation of activity took the form of deactivation. Yet, the deactivation response was not evident in either cortical area during the paired presentation of visual and auditory stimuli. These data suggest that cross-modal inhibitory processes operate within traditional modality-specific cortices and that these processes can be switched on or off in different circumstances.
Neural Evidence Linking Visual Object Enumeration and Attention
Authors: Sathian K. , Simon Tony J. , Peterson Scott , Patel Gargi A. , Hoffman John M. , Grafton Scott T.
Published: July 2002

Visual object enumeration is rapid and accurate for four or fewer items but slow and error-prone for over four items. This dichotomy has recently been linked to visual attentional phenomena by findings suggesting that “subitizing” of small sets of objects is preattentive whereas “counting” of over four items demands spatial shifts of attention. We evaluated this link at a neural level, using H2 15O positron emission tomography to measure changes in regional cerebral blood flow while subjects enumerated the number of target vertical bars that “popped out”of a 16-bar visual display consisting of both horizontal and vertical bars. Relative to a condition with a single target, subitizing (one to four targets) activated foci in the occipital extras-triate cortex, consistent with involvement of early, preattentive visual processes. Relative to subitizing, counting (five to eight targets) activated a widespread network of brain regions, including multiple foci implicated in shifting visual attention— large regions of the superior parietal cortex bilaterally and a focus in the right inferior frontal cortex. These results offer the first direct neural support for mapping the subitizing-counting dichotomy onto separable processes mediating preattentive vision and shifts of visual attention.
Spatio-Temporal Prediction Modulates the Perception of Self-Produced Stimuli
Authors: Blakemore Sarah-J. , Frith Chris D. , Wolpert Daniel M.
Published: July 2002

We investigated why self-produced tactile stimulation is perceived as less intense than the same stimulus produced externally. A tactile stimulus on the palm of the right hand was either externally produced, by a robot or self-produced by the subject. In the conditions in which the tactile stimulus was self-produced, subjects moved the arm of a robot with their left hand to produce the tactile stimulus on their right hand via a second robot. Subjects were asked to rate intensity of the tactile sensation and consistently rated self-produced tactile stimuli as less tickly, intense, and pleasant than externally produced tactile stimuli. Using this robotic setup we were able to manipulate the correspondence between the action of the subjects' left hand and the tactile stimulus on their right hand. First, we parametrically varied the delay between the movement of the left hand and the resultant movement of the tactile stimulus on the right hand. Second, we implemented varying degrees of trajectory perturbation and varied the direction of the tactile stimulus movement as a function of the direction of left-hand movement. The tickliness rating increased significantly with increasing delay and trajectory perturbation. This suggests that self-produced movements attenuate the resultant tactile sensation and that a necessary requirement of this attenuation is that the tactile stimulus and its causal motor command correspond in time and space. We propose that the extent to which self-produced tactile sensation is attenuated (i.e., its tickliness) is proportional to the error between the sensory feedback predicted by an internal forward model of the motor system and the actual sensory feedback produced by the movement.
A Model of Invariant Object Recognition in the Visual System: Learning Rules, Activation Functions, Lateral Inhibition, and Information-Based Performance Measures
Authors: Rolls Edmund T. , Milward T.
Published: July 2002

VisNet2 is a model to investigate some aspects of invariant visual object recognition in the primate visual system. It is a four-layer feedforward network with convergence to each part of a layer from a small region of the preceding layer, with competition between the neurons within a layer and with a trace learning rule to help it learn transform invariance. The trace rule is a modified Hebbian rule, which modifies synaptic weights according to both the current firing rates and the firing rates to recently seen stimuli. This enables neurons to learn to respond similarly to the gradually transforming inputs it receives, which over the short term are likely to be about the same object, given the statistics of normal visual inputs. First, we introduce for VisNet2 both single-neuron and multiple-neuron information-theoretic measures of its ability to respond to transformed stimuli. Second, using these measures, we show that quantitatively resetting the trace between stimuli is not necessary for good performance. Third, it is shown that the sigmoid activation functions used in VisNet2, which allow the sparseness of the representation to be controlled, allow good performance when using sparse distributed representations. Fourth, it is shown that VisNet2 operates well with medium-range lateral inhibition with a radius in the same order of size as the region of the preceding layer from which neurons receive inputs. Fifth, in an investigation of different learning rules for learning transform invariance, it is shown that VisNet2 operates better with a trace rule that incorporates in the trace only activity from the preceding presentations of a given stimulus, with no contribution to the trace from the current presentation, and that this is related to temporal difference learning.
A Signal-Flow-Graph Approach to On-line Gradient Calculation
Authors: Campolucci Paolo , Uncini Aurelio , Piazza Francesco
Published: July 2002

A large class of nonlinear dynamic adaptive systems such as dynamic recurrent neural networks can be effectively represented by signal flow graphs (SFGs). By this method, complex systems are described as a general connection of many simple components, each of them implementing a simple one-input, one-output transformation, as in an electrical circuit. Even if graph representations are popular in the neural network community, they are often used for qualitative description rather than for rigorous representation and computational purposes. In this article, a method for both on-line and batch-backward gradient computation of a system output or cost function with respect to system parameters is derived by the SFG representation theory and its known properties. The system can be any causal, in general nonlinear and time-variant, dynamic system represented by an SFG, in particular any feedforward, time-delay, or recurrent neural network. In this work, we use discrete-time notation, but the same theory holds for the continuous-time case. The gradient is obtained in a straightforward way by the analysis of two SFGs, the original one and its adjoint (obtained from the first by simple transformations), without the complex chain rule expansions of derivatives usually employed.

This method can be used for sensitivity analysis and for learning both off-line and on-line. On-line learning is particularly important since it is required by many real applications, such as digital signal processing, system identification and control, channel equalization, and predistortion.
Spotting Neural Spike Patterns Using an Adversary Background Model
Authors: Gat Itay , Tishby Naftali
Published: July 2002

The detection of a specific stochastic pattern embedded in an unknown background noise is a difficult pattern recognition problem, encountered in many applications such as word spotting in speech. A similar problem emerges when trying to detect a multineural spike pattern in a single electrical recording, embedded in the complex cortical activity of a behaving animal. Solving this problem is crucial for the identification of neuronal code words with specific meaning. The technical difficulty of this detection is due to the lack of a good statistical model for the background activity, which rapidly changes with the recording conditions and activity of the animal. This work introduces the use of an adversary background model. This model assumes that the background “knows” the pattern sought, up to a first-order statistics, and this “knowledge” creates a background composed of all the permutations of our pattern. We show that this background model is tightly connected to the type-based information-theoretic approach. Furthermore, we show that computing the likelihood ratio is actually decomposing the log-likelihood distribution according to types of the empirical counts. We demonstrate the application of this method for detection of the reward patterns in the basal ganglia of behaving monkeys, yielding some unexpected biological results.
Rate Coding Versus Temporal Order Coding: What the Retinal Ganglion Cells Tell the Visual Cortex
Authors: Rullen Rufin Van , Thorpe Simon J.
Published: July 2002

It is often supposed that the messages sent to the visual cortex by the retinal ganglion cells are encoded by the mean firing rates observed on spike trains generated with a Poisson process. Using an information transmission approach, we evaluate the performances of two such codes, one based on the spike count and the other on the mean interspike interval, and compare the results with a rank order code, where the first ganglion cells to emit a spike are given a maximal weight. Our results show that the rate codes are far from optimal for fast information transmission and that the temporal structure of the spike train can be efficiently used to maximize the information transfer rate under conditions where each cell needs to fire only one spike.
A Parallel Mixture of SVMs for Very Large Scale Problems
Authors: Collobert Ronan , Bengio Samy , Bengio Yoshua
Published: July 2002

Support vector machines (SVMs) are the state-of-the-art models for many classification problems, but they suffer from the complexity of their training algorithm, which is at least quadratic with respect to the number of examples. Hence, it is hopeless to try to solve real-life problems having more than a few hundred thousand examples with SVMs. This article proposes a new mixture of SVMs that can be easily implemented in parallel and where each SVM is trained on a small subset of the whole data set. Experiments on a large benchmark data set (Forest) yielded significant time improvement (time complexity appears empirically to locally grow linearly with the number of examples). In addition, and surprisingly, a significant improvement in generalization was observed.
Natural Gradient Works Efficiently in Learning
Authors: Amari Shun-ichi
Published: July 2002

When a parameter space has a certain underlying structure, the ordinary gradient of a function does not represent its steepest direction, but the natural gradient does. Information geometry is used for calculating the natural gradients in the parameter space of perceptrons, the space of matrices (for blind source separation), and the space of linear dynamical systems (for blind source deconvolution). The dynamical behavior of natural gradient online learning is analyzed and is proved to be Fisher efficient, implying that it has asymptotically the same performance as the optimal batch estimation of parameters. This suggests that the plateau phenomenon, which appears in the backpropagation learning algorithm of multilayer perceptrons, might disappear or might not be so serious when the natural gradient is used. An adaptive method of updating the learning rate is proposed and analyzed.
On Selecting the Right Yardstick
Authors: Singer Michael J. , Witmer Bob G.
Published: July 2002

In an article that discussed both the conceptual aspects of presence and the practical considerations of measuring the concept (Witmer & Singer, 1998), we argued that both involvement and immersion are necessary for experiencing presence. The article also presented two questionnaires we have developed, an Immersive Tendencies Questionnaire (ITQ) and a Presence Questionnaire (PQ). Our analyses showed that they are internally consistent with high reliability, there is a weak but consistent positive relation between presence and performance, the ITQ predicts presence as measured by the PQ, and individuals reporting more simulator sickness symptoms report less presence than those reporting fewer symptoms. In this issue, Slater (1999) critiques our approach to measuring presence as represented by the PQ. Dr. Slater finds our definitions of presence helpful and that our concept of immersion is part of his understanding of the meaning of presence. Dr. Slater then argues that both our approach to measuring presence and the PQ are conceptually flawed. In his critique, he raises statistical questions about our measure, concluding that the PQ is not a measure of presence at all. He concludes by arguing against the validity of the measure and stating that he would not use the PQ in his research. In this article, we argue that the PQ is based in the same conceptual structure that is accepted by Dr. Slater, and that the PQ represents a fundamentally sound approach—although not the only approach—to measuring presence. Dr. Slater's statistical arguments are shown to be incorrect simplifications, as he acknowledges in his critique. We also demonstrate that individual PQ items still correlate significantly with the PQ total score even when the PQ total is adjusted to remove the score on individual items from that total. Finally, we rebut Slater's argument concerning the validity of the measure, and suggest that researchers not be constrained by an equipment-oriented model of the presence experience.
Analysis of the (μ/μ, λ)-ES on the Parabolic Ridge
Authors: Oyman A. Irfan , Beyer Hans-Georg
Published: July 2002

The progress behavior of evolution strategies (ES) using recombination is analyzed in this paper on the parabolic ridge. This test function represents landscapes far from the optimum. The ES algorithms with intermediate and dominant recombination are considered in the analysis. The derivations are presented for intermediate recombination. Thereafter, the formulae for dominant recombination are obtained using the so-called surrogate mutation model. In the analysis, the formulae are derived for the progress rate φ and for the stationary distance R(∞) to the ridge axis. As a result, it will be shown that the progress rate φ can increase if recombination is applied. Simulations are used to show the appropriateness of the formulae derived.
Building a Micro Foundation for Industrial Ecology
Authors: Andrews Clinton J.
Published: July 2002

Abstract:Industrial ecologists study phenomena at several distinct scales, and linking the resulting insights could advance the field. The disciplines of ecology and economics have each attempted, with partial success, to accomplish this by building a behavioral micro foundation, and industrial ecology should do the same. These fields all study evolving systems made up of autonomous individuals who operate in a largely self‐interested manner, exhibit diverse behaviors, and self‐organize many higher‐level structures such as communities or sectors in a bottom‐up fashion. Industrial ecologists should explicitly attempt to integrate empirical and normative views about agency, and more carefully distinguish between two types of agents—firms and individual humans.
THE HOLY MAN'S HUT AS A SYMBOL OF STABILITY IN JAPANESE BUDDHIST PILGRIMAGE
Authors: MacWilliams Mark
Published: July 2002

In this paper, I examine the way holy men's huts are portrayed in eighteenth century Buddhist tales from the Saikoku and Bandô Japanese Buddhist pilgrimage routes. These stories suggest that holy men's huts are ultimately located in places beyond the ordinary human life of suffering, marked as it is by impermanence and instability. That the hermit's hut transcends the transient world is indicated in two important ways in these tales. First, the holy men's statues of the Buddhist celestial bodhisattva Kannon, which they carry or carve while on the road, display a preternatural mobility or immobility which force the ascetics to stop their peregrination. Second, the places they build their huts to enshrine the statues are revealed as spiritual places (reijô), Pure Land paradises where the living Kannon has a permanent abode. These holy men's huts were the prototypes of the Saikoku and Bandô temples that continue to attract multitudes of Japanese pilgrims who travel there even today seeking freedom from the sorrows of transmigration.
THE COMPOSITION OF CYCLOPOID ASSEMBLAGES IN ECOLOGICALLY DIFFERENT GROUNDWATER HABITATS OF A DANUBE RIVERINE WETLAND IN AUSTRIA
Authors: Pospisil Peter
Published: July 2002

The cyclopoid assemblages of three groundwater monitoring sites in the Danube wetlands were investigated from mid 1996 to end 1997. One of these sites, located 200 m from surface waters, represents a stable, oligotrophic habitat (characterized by low temperature fluctuations and low dissolved organic carbon (DOC)-values). Six groundwater cyclopoids permanently inhabit this habitat. At two other sites, located closely to a backwater of the Danube and characterized by strong surface water influences, only four stygobitic cyclopoids occur altogether. These data support modern opinions, which stress that groundwater habitats are more heterogeneous and display higher biodiversity (i. e., higher species richness) of selected crustacean taxocoenoses (in this case, Cyclopoida) than expected earlier. Die Grundwassercyclopiden dreier Untersuchungsstellen in den Donauauen wurden von Juni 1996 bis Dezember 1997 untersucht. Eine dieser Stellen reprasentierte ein stabiles, oligotrophes Habitat (charakterisiert durch geringe Temperaturschwankungen und niedrige ''dissolved organic carbon'' (DOC)-Werte). Dieses Habitat wurde von sechs Grundwassercyclopiden standig besiedelt, im Vergleich zu nur vier Arten an den beiden anderen Stellen zusammen, die durch das nahe Oberflachengewasser stark beeinflusst wurden. Diese Beobachtungen bestatigen die moderne Ansicht, dass im Grundwasser eine grossere Habitatdiversitat sowie eine grossere Biodiversitat (d. h., Artenreichtum) von ausgewahlten Crustaceen-Taxozonosen (in diesem Fall Cyclopoida) zu finden ist als bisher angenommen.
Electropharyngeograms and stylet activity of second stage juveniles of Globodera rostochiensis
Authors: Perry Roland , Rolfe Richard
Published: July 2002

Analysis of the contraction and relaxation of pharyngeal musculature derives from measurements of electrical currents, termed electropharyngeograms (EPG). EPG of stylet protractor muscle activity of second stage juveniles (J2) of Globodera rostochiensis, in response to 0.1, 1.0 and 10 mg ml-1 concentrations of the neurotransmitter serotonin, have now been obtained and correlated with stylet protrusion and retraction using video analysis. The antagonist, gramine (10 mg ml-1), incorporated with 10 mg ml-1 serotonin, almost completely eliminated stylet thrusting by J2. Stylet movement can be determined accurately over extended periods with EPG and this approach has potential for investigating factors involved in activation and perturbation of stylet protrusion.
Molecular and morphological characterisation of two reproductively isolated species with mirror-image anatomy (Nematoda: Cephalobidae)
Authors: Ley Paul De , Felix Marie-Anne , Frisse Linda , Nadler Steven , Sternberg Paul , Thomas W. Kelley
Published: July 2002

Detailed descriptions are given of the amphimictic nematode strains PS1158,
PS2052 and PS2160, which are unusual in that they only differ in predominant
body handedness. Although these strains are morphologically identical in all
other respects, published reproductive data and new DNA sequence data of the
D2/D3 region of the large subunit rRNA gene show that they do represent two
separate species. On the basis of comparison with type material, the
left-handed strains PS1158 and PS2160 are identified as Acrobeloides
bodenheimeri, and the right-handed strain PS2052 as A. camberenensis, which
is re-instated as a valid species. A. bodenheimeri and its relatives exhibit
various types of diagnostic and taxonomic problems at species level, and it
is shown that D2/D3 sequence data provide an important new diagnostic tool
for addressing these problems. Phylogenetic analysis shows that two
right-handed parthenogenetic strains identified as A. maximus represent a
third species which is more closely related to A. camberenensis than to A.
bodenheimeri. Caracterisation morphologique et moleculaire de deux especes
intersteriles de chiralite contraire (Nematoda: Cephalobidae) - Une
description detaillee est donnee des souches amphimictiques de nematodes
PS1158, PS2052 et PS2160, souches inhabituelles car differant par la
chiralite du corps. Bien que ces souches soient morphologiquement identiques
sous tout autre rapport, les resultats publies de tests de croisement et de
nouvelles donnees concernant la sequence d'ADN de la region D2/D3 du gene de
la grosse sous-unite d'ARN ribosomal montrent qu'elles representent en fait
deux especes distinctes. Se fondant sur une comparaison avec le materiel
type, les souches sinistres PS1158 et PS2160 sont identifiees comme
Acrobeloides bodenheimeri et la souche dextre PS2052 comme A. camberenensis,
ainsi retabli comme espece valide. A. bodenheimeri et les especes proches
posent differents problemes diagnostiques et taxinomiques au niveau
specifique, et nous montrons que les donnees de sequence D2/D3 fournissent
un nouvel outil diagnostique important pour aborder ces problemes. L'analyse
phylogenetique montre que deux souches parthenogenetiques dextres
identifiees comme A. maximus representent en fait une troisieme espece, plus
proche de A. camberenensis que de A. bodenheimeri.
Clay mineral diagenesis in sedimentary basins — a key to the prediction of rock properties. Examples from the North Sea Basin
Authors: Bjørlykke K.
Published: July 2002

Dissolution of feldspar and mica and precipitation of kaolinite require a through flow of meteoric water to remove cations such as Na+ and K+ and silica. Compaction driven pore-water flow is in most cases too slow to be significant in terms of transport of solids. The very low solubility of A1 suggests that precipitation of new authigenic clay minerals requires unstable Al-bearing precursor minerals. Chlorite may form diagenetically from smectite and from kaolinite when a source of Fe and Mg is present. In the North Sea Basin, the main phase of illite precipitation reducing the quality of Jurassic reservoirs occurs at depths close to 4 km (130-140°C) but the amount of illite depends on the presence of both kaolinite and K-feldspar. Clay mineral reactions in shales and sandstones are very important factors determining mechanical and chemical compaction and are thus critical for realistic basin modelling.
Geological controls on kaolin particle shape and consequences for mineral processing
Authors: Psyrillos A. , Howe J. H. , Manning D. A. C. , Burley S. D.
Published: July 2002

The kaolinized granites of St. Austell, England, are worked to produce a range of china clay products, for some of which the kaolin has to meet stringent particle shape and size specifications. Systematic petrographic study indicates that kaolin occurs in the form of two textural types: (i) finely crystalline kaolin (typically <5 µm in average diameter), which infills dissolution porosity of granitic feldspars, and (ii) coarsely crystalline vermiform aggregates (up to 100 µm or more in length), which are closely associated with expanded micas. The vermiform aggregates are characterized by an intergrowth of mica and kaolin crystals, which can be observed at scales of resolution offered by TEM. Textural and chemical evidence suggest that the expanded mica texture is probably the result of preferential precipitation of kaolin along mica cleavage planes and is not simply a process of chemical replacement.

Petrographic examination of kaolin slurries sampled at different points in a typical refinery circuit indicates that platy products with high aspect ratio are derived exclusively from raw materials rich in vermiform aggregates. The fine scale intergrowth of kaolin and mica within the aggregates results in circumstances where mica persists through to fine grained products. Furthermore, the absence of Fe or other chemical components in the kaolin structure suggests that any iron reported for the final products may be a consequence of the presence of Fe-bearing mica within a very fine grained intergrowth.
Applied clay mineralogy today and tomorrow
Authors: Murray H. H.
Published: July 2002

The clay minerals kaolin, smectite and palygorskite-sepiolite are among the world's most important and useful industrial minerals. Clay minerals are important in a number of geological applications such as stratigraphic correlations, indicators of environments of deposition and temperature for generation of hydrocarbons. In agriculture, the clay minerals are a major component of soils and determinant of soil properties. The clay minerals are important in construction where they are a major constituent in brick and tile. The physical and chemical properties of the clay minerals determine their utilization in the process industries.

What about tomorrow? Processing techniques will be improved and new equipment will be available so that improved clay mineral products will be available. Pillared clays and nanocomposites will become important. Further developments in organoclay technology and surface treatments will provide new usages for these special clays. Tomorrow will see further growth and utilization of the clay minerals.
An enriched mantle source for Italy's melilitite-carbonatite association as inferred by its Nd-Sr isotope signature
Authors: Castorina F. , Stoppa F. , Cundari A. , Barbieri M.
Published: July 2002

New Sr-Nd isotope data were obtained from Late Pleistocene carbonatite-kamafugite associations from the Umbria-Latium Ultra-Alkaline District of Italy (ULUD) with the aim of constraining their origin and possible mantle source(s). This is relevant to the origin and evolution of ultrapotassic (K/Na ≫2) and associated rocks generally, notably the occurrences from Ugandan kamafugites,Western Australian lamproites and South African orangeites. The selected ULUD samples yielded 87Sr/86Sr and 143Nd/144Nd ranging from 0.7100 to 0.7112 and from 0.5119 to 0.5121 respectively, similar to cratonic potassic volcanic rocks with higher Rb/Sr and lower Sm/Nd ratios than Bulk Earth. Silicate and carbonate fractions separated from melilitite are in isotopic equilibrium, supporting the view that they are cogenetic. The ULUD carbonatites yielded the highest radiogenic Sr so far reported for carbonatites. In contrast, sedimentary limestones from ULUD basement formations are lower in radiogenic Sr, i.e. 87Sr/86Sr = 0.70745–0.70735. The variation trend of ULUD isotopic compositions is similar to that reported for Ugandan kamafugites and Western Australian lamproites and overlaps the values for South African orangeites in the εSr-εNd diagram. A poor correlation between Sr/Nd and 87Sr/86Sr ratios in ULUD rocks is inconsistent with a mantle source generated by subduction-driven processes, while the negligible Sr and LREE in sedimentary limestones from the ULUD region fail to account for a hypothetical limestone assimilation process. The Nd model ages of 1.5–1.9 Ga have been inferred for a possible metasomatic event, allowing further radiogenic evolution of the source, a process which may have occurred in isolation until eruption time. While the origin of this component remains speculative, the Sr-Nd isotope trend is consistent with a simple mixing process involving an OIB-type mantle and a component with low εNd and high εSr.
Carbonatite-melilitite association in the Italian collision zone and the Ugandan rifted craton: significant common factors
Authors: Bailey D. K. , Collier J. D.
Published: July 2002

Italian carbonatites form part of a suite with melilitites, normally an association characteristic of continental interiors; the perfect analogue of the Italian suite being the kamafugites (from the type area in SW Uganda, where the western branch of the East African Rift Zone cuts across the craton). The latter are commonly attributed to plume generation, whereas the Italian carbonatites, strung along the Appennine front, are usually linked to subduction. Evidently these two mechanisms are not essential, since neither can apply in both provinces. This conclusion is re-inforced by the related magmatism registered in both provinces in the Cretaceous. Phlogopite is ubiquitous in the mantle debris, and compositions from the two provinces overlap. Xenolithic phlogopites are distinct from cognate micas in the lavas, and from the carrier melt compositions, with similar distribution patterns in both suites. Kamafugitic magmas must be products of exceptional conditions, and added to the many near-identical magmatic features, the Italian and Ugandan volcanoes have sampled similar mantle conditions. Although the large scale geodynamic regimes are in total contrast, as are the deep mantle tomographic structures, the crucial common factor at the igneous province level is extensional tectonics. Extension, promoting release of volatiles (esp. CO2), is the vital trigger for this small volume, primary magmatism.
Eclogite facies relics in metabasites from the Sierra de Guadarrama (Spanish Central System): P-T estimations and implications for the Hercynian evolution
Authors: Barbero L. , Villaseca C.
Published: July 2002

Relics of HP-MT eclogitic assemblages related to the first metamorphic stage of the Hercynian orogeny in the Sierra de Guadarrama (Spanish Central System, SCS) are preserved as boudins of pre-Ordovician metabasites enclosed by felsic gneisses. Textures indicate a multi-stage metamorphic history starting in the MT eclogite facies (as deduced from the presence of omphacite and rutile included in garnet) and continuing through medium to low pressure granulite and retrograde amphibolite-greenschist facies. Thermobarometric calculations in the eclogitic paragenesis yield pressures of ∼14 kbar for temperatures in the range 725-775°C. Thermobarometry for the subsequent granulitic stage indicates a significant drop in pressure (P < 10 kbar) for similar temperatures of ∼750°C. Metabasites vary from gabbro to leucotonalites showing the typical Fe enrichment of the tholeiitic series. Chemical characteristics indicate a derivation from low-pressure crystallization of tholeiitic melts more enriched than typical MORB compositions. Their original location far from continental margins as evidenced by the absence of ophiolitic material in the area and their association with platform sediments suggests that eclogitization was related to intracontinental crustal subduction and thickening. The P-T conditions estimated in the metabasites for the first metamorphic stage are similar to ones deduced for the surrounding metasediments and suggest that the Hercynian crust could have reached a thickness of ∼70–80 km, which is more than the double the present thickness.
Wollastonite-bearing assemblages from the Dalradian at Fraserburgh, northeast Scotland and their bearing on the emplacement of garnetiferous granitoid sheets
Authors: Johnson T. E. , Hudson N. F. C. , Droop G. T. R.
Published: July 2002

Metasediments of the Tayvallich Subgroup of the Dalradian at Kinnairds Head, Fraserburgh are metamorphosed to sillimanite + K-feldspar grade and form part of the classic high-T low-P Buchan metamorphic terrain. Pelitic samples constrain peak-metamorphic conditions to 615±13°C and 2.2±0.2 kbar. At or close to the metamorphic peak, irregular garnetiferous aplites and autopegmatite bodies intruded the metasediments. Thin marble bands within the sequence are dominated by calcite with diopside, and equilibrated with relatively CO2-rich, internally buffered fluids. Where these are in close proximity to granitoid pegmatites, wollastonite dominates the matrix, and fractures and veins running through the rock contain concentrations of grossular and vesuvianite. With increasing distance from the pegmatite, vesuvianite and then grossular disappear, and wollastonite is only patchily developed. Such occurrences require a flushing of the marble by metasomatic (siliceous and aluminous) aqueous fluids which were derived from the de-watering of the adjacent pegmatite as it crystallized. The large quantities of dissolved silica led to pervasive wollastonite formation for several metres. The smaller quantities of Al reacted to form Ca-Al-silicates which were confined to the fractures.
The mineralogy of waste and waste disposal
Authors: Hodson M. E. , Bloodworth A.
Published: July 2002

Mineralogy has many applications in the business of waste and waste disposal:

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precipitation of minerals and adsorption of elements and compounds to mineral surfaces can serve to immobilize pollutants or concentrate them for recycling

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release of elements and compounds can occur by the converse processes of dissolution and desorption

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minerals can act as impermeable barriers between pollutants and the environment

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minerals can be used as analogues to determine the long-term stability of engineered materials used for the encapsulation of waste.

The Applied Mineralogy Group of the Mineralogical Society organized a meeting ‘The mineralogy of waste and waste disposal’ held at the British Geological Survey, Keyworth, Nottingham, on 25th September 2000. The meeting attracted members of both the academic (Earth Science, Chemistry and Material Science departments) and industrial communities. A wide variety of papers was presented dealing with such diverse issues as nuclear waste disposal and the recycling of phosphorus from wastewater. Seven of the papers are collected here.