bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Pictorial Illusion on Prehension and Perception
Authors: Haffenden Angela M. , Goodale Melvyn A.
Published: July 2002

The present study examined the effect of a size-contrast illusion (Ebbinghaus or Titchener Circles Illusion) on visual perception and the visual control of grasping movements. Seventeen right-handed participants picked up and, on other trials, estimated the size of fipoker-chipfl disks, which functioned as the target circles in a three-dimensional version of the illusion. In the estimation condition, subjects indicated how big they thought the target was by separating their thumb and forefinger to match the target's size. After initial viewing, no visual feedback from the hand or the target was available. Scaling of grip aperture was found to be strongly correlated with the physical size of the disks, while manual estimations of disk size were biased in the direction of the illusion. Evidently, grip aperture is calibrated to the true size of an object, even when perception of object size is distorted by a pictorial illusion, a result that is consistent with recent suggestions that visually guided prehension and visual perception are mediated by separate visual pathways.
Can Face Recognition Really be Dissociated from Object Recognition?
Authors: Gauthier Isabel , Behrmann Marlene , Tarr Michael J.
Published: July 2002

We argue that the current literature on prosopagnosia fails to demonstrate unequivocal evidence for a disproportionate impairment for faces as compared to nonface objects. Two prosopagnosic subjects were tested for the discrimination of objects from several categories (face as well as nonface) at different levels of categorization (basic, subordinate, and exemplar levels). Several dependent measures were obtained including accuracy, signal detection measures, and response times. The results from Experiments 1 to 4 demonstrate that, in simultaneous-matching tasks, response times may reveal impairments with nonface objects in subjects whose error rates only indicate a face deficit. The results from Experiments 5 and 6 show that, given limited stimulus presentation times for face and nonface objects, the same subjects may demonstrate a deªcit for both stimulus categories in sensitivity. In Experiments 7, 8 and 9, a match-to-sample task that places greater demands on memory led to comparable recognition sensitivity with both face and nonface objects. Regardless of object category, the prosopagnosic subjects were more affected by manipulations of the level of categorization than normal controls. This result raises questions regarding neuropsychological evidence for the modularity of face recognition, as well as its theoretical and methodological foundations.
DEA: An Architecture for Goal Planning and Classification
Authors: Fleuret François , Brunet Eric
Published: July 2002

We introduce the differential efficiency algorithm, which partitions a perceptive space during unsupervised learning into categories and uses them to solve goal-planning and classification problems. This algorithm is inspired by a biological model of the cortex proposing the cortical column as an elementary unit. We validate the generality of this approach by testing it on four problems with continuous time and no reinforcement signal until the goal is reached (constrained object moves, Hanoi tower problem, animat control, and simple character recognition).
Does Corticothalamic Feedback Control Cortical Velocity Tuning?
Authors: Hillenbrand Ulrich , Hemmen J. Leo van
Published: July 2002

The thalamus is the major gate to the cortex, and its contribution to cortical receptive field properties is well established. Cortical feedback to the thalamus is, in turn, the anatomically dominant input to relay cells, yet its influence on thalamic processing has been difficult to interpret. For an understanding of complex sensory processing, detailed concepts of the corticothalamic interplay need to be established. To study corticogeniculate processing in a model, we draw on various physiological and anatomical data concerning the intrinsic dynamics of geniculate relay neurons, the cortical influence on relay modes, lagged and nonlagged neurons, and the structure of visual cortical receptive fields. In extensive computer simulations, we elaborate the novel hypothesis that the visual cortex controls via feedback the temporal response properties of geniculate relay cells in a way that alters the tuning of cortical cells for speed.
Enhanced 3D Shape Recovery Using the Neural-Based Hybrid Reflectance Model
Authors: Cho Siu-Yeung , Chow Tommy W. S.
Published: July 2002

It is known that most real surfaces usually are neither perfectly Lambertian model nor ideally specular model; rather, they are formed by the hybrid structure of these two models. This hybrid reflectance model still suffers from the noise, strong specular, and unknown reflectivity conditions. In this article, these limitations are addressed, and a new neural-based hybrid reflectance model is proposed. The goal of this method is to optimize a proper reflectance model by learning the weight and parameters of the hybrid structure of feedforward neural networks and radial basis function networks and to recover the 3D object shape by the shape from shading technique with this resulting model. Experimental results, including synthetic and real images, were performed to demonstrate the performance of the proposed reflectance model in the case of different specular effects and noise environments.
Learning to Recognize Three-Dimensional Objects
Authors: Roth Dan , Yang Ming-Hsuan , Ahuja Narendra
Published: July 2002

A learning account for the problem of object recognition is developed within the probably approximately correct (PAC) model of learnability. The key assumption underlying this work is that objects can be recognized (or discriminated) using simple representations in terms of syntactically simple relations over the raw image. Although the potential number of these simple relations could be huge, only a few of them are actually present in each observed image, and a fairly small number of those observed are relevant to discriminating an object.

We show that these properties can be exploited to yield an efficient learning approach in terms of sample and computational complexity within the PAC model. No assumptions are needed on the distribution of the observed objects, and the learning performance is quantified relative to its experience. Most important, the success of learning an object representation is naturally tied to the ability to represent it as a function of some intermediate representations extracted from the image.

We evaluate this approach in a large-scale experimental study in which the SNoW learning architecture is used to learn representations for the 100 objects in the Columbia Object Image Library. Experimental results exhibit good generalization and robustness properties of the SNoW-based method relative to other approaches. SNoW's recognition rate degrades more gracefully when the training data contains fewer views, and it shows similar behavior in some preliminary experiments with partially occluded objects.
Toward a Biophysically Plausible Bidirectional Hebbian Rule
Authors: Grzywacz Norberto M. , Burgi Pierre-Yves
Published: July 2002

Although the commonly used quadratic Hebbian-;anti-Hebbian rules lead to successful models of plasticity and learning, they are inconsistent with neurophysiology. Other rules, more physiologically plausible, fail to specify the biological mechanism of bidirectionality and the biological mechanism that prevents synapses from changing from excitatory to inhibitory, and vice versa. We developed a synaptic bidirectional Hebbian rule that does not suffer from these problems. This rule was compared with physiological homosynaptic conditions in the hippocampus, with the results indicating the consistency of this rule with long-term potentiation (LTP) and long-term depression (LTD) phenomenologies. The phenomenologies considered included the reversible dynamics of LTP and LTD and the effects of N-methyl-D-aspartate blockers and phosphatase inhibitors.
Prediction Games and Arcing Algorithms
Authors: Breiman Leo
Published: July 2002

The theory behind the success of adaptive reweighting and combining algorithms (arcing) such as Adaboost (Freund & Schapire, 1996a, 1997) and others in reducing generalization error has not been well understood. By formulating prediction as a game where one player makes a selection from instances in the training set and the other a convex linear combination of predictors from a finite set, existing arcing algorithms are shown to be algorithms for finding good game strategies. The minimax theorem is an essential ingredient of the convergence proofs. An arcing algorithm is described that converges to the optimal strategy. A bound on the generalization error for the combined predictors in terms of their maximum error is proven that is sharper than bounds to date. Schapire, Freund, Bartlett, and Lee (1997) offered an explanation of why Adaboost works in terms of its ability to produce generally high margins. The empirical comparison of Adaboost to the optimal arcing algorithm shows that their explanation is not complete.
Seeing White: Qualia in the Context of Decoding Population Codes
Authors: Lehky Sidney R. , Sejnowski Terrence J.
Published: July 2002

When the nervous system is presented with multiple simultaneous inputs of some variable, such as wavelength or disparity, they can be combined to give rise to qualitatively new percepts that cannot be produced by any single input value. For example, there is no single wavelength that appears white. Many models of decoding neural population codes have problems handling multiple inputs, either attempting to extract a single value of the input parameter or, in some cases, registering the presence of multiple inputs without synthesizing them into something new. These examples raise a more general issue regarding the interpretation of population codes. We propose that population decoding involves not the extraction of specific values of the physical inputs, but rather a transformation from the input space to some abstract representational space that is not simply related to physical parameters. As a specific example, a four-layer network is presented that implements a transformation from wavelength to a high-level hue-saturation color space.
Power and Problems of Performance across Ethnic Lines, An Alternative Approach to Nontraditional Casting
Authors: Sun William H.
Published: July 2002

Nontraditional casting has long been of interest to TDR. Here Contributing Editor Sun argues that expanding job opportunities for nonwhite actors is only part of the situation. Another aspect includes asking when, if ever, ought roles written for people-of-color be played by actors of other ethnicities.
Carnival in Galicia Scattered Ants, Whipped Backs, and Hammered Plowshares
Authors: Harris Max
Published: July 2002

Vigorous masking, dancing, music, drinking, and celebratory chaos mixing old and new animate Carnival in Portugal and northern Spain. Harris attended five Galician carnivals in 1998, reporting here on his experiences.
Desktop Theater: Keyboard Catharsis and the Masking of Roundheads
Authors: Jenik Adriene
Published: July 2002

What is theatre? Can it take place separate from the body, voices, and shared space? How does Waiting for Godot play online? What about original works? Works created in real time with mul-tiple players/characters? The genre hinges on the “democratization of creative practice” and the author invites readers to make their own Desktop Theater.
Mapping Algorithms for Real-Time Control of an Avatar Using Eight Sensors
Authors: Semwal Sudhanshu K. , Hightower Ron , Stansfield Sharon
Published: July 2002

In a virtual environment for small groups of interacting participants, it is important that the physical motion of each participant be replicated by synthetic human forms in real time. Sensors on a user's body are used to drive an inverse kinematics algorithm. Such iterative algorithms for solving the general inverse kinematics problem are too slow for a real-time interactive environment. In this paper we present analytic, constant time methods to solve the inverse kinematics problem and drive an avatar figure. Our sensor configuration has only eight sensors per participant, so the sensor data is augmented with information about natural body postures. The algorithm is fast, and the resulting avatar motion approximates the actions of the participant quite well. This new analytic solution resolves a problem with an earlier iterative algorithm that had a tendency to position knees and elbows of the avatar in awkward and unnatural positions.
Where Genetic Algorithms Excel
Authors: Baum Eric B. , Boneh Dan , Garrett Charles
Published: July 2002

We analyze the performance of a genetic algorithm (GA) we call Culling, and a variety of other algorithms, on a problem we refer to as the Additive Search Problem (ASP). We show that the problem of learning the Ising perceptron is reducible to a noisy version of ASP. Noisy ASP is the first problem we are aware of where a genetic-type algorithm bests all known competitors. We generalize ASP to k-ASP to study whether GAs will achieve “implicit parallelism” in a problem with many more schemata. GAs fail to achieve this implicit parallelism, but we describe an algorithm we call Explicitly Parallel Search that succeeds. We also compute the optimal culling point for selective breeding, which turns out to be independent of the fitness function or the population distribution. We also analyze a mean field theoretic algorithm performing similarly to Culling on many problems. These results provide insight into when and how GAs can beat competing methods.
Effects of Compression on Language Evolution
Authors: Teal Tracy K. , Taylor Charles E.
Published: July 2002

Abstract For many adaptive complex systems information about the environment is not simply recorded in a look-up table, but is rather encoded in a theory, schema, or model, which compresses information. The grammar of a language can be viewed as such a schema or theory. In a prior study [Teal et al., 1999] we proposed several conjectures about the learning and evolution of language that should follow from these observations: (C1) compression aids in generalization; (C2) compression occurs more easily in a “smooth”, as opposed to a “rugged”, problem space; and (C3) constraints from compression make it likely that natural languages evolve towards smooth string spaces. This previous work found general, if not complete support for these three conjectures. Here we build on that study to clarify the relationship between Minimum Description Length (MDL) and error in our model and examine evolution of certain languages in more detail. Our results suggest a fourth conjecture: that all else being equal, (C4) more complex languages change more rapidly during evolution.
CONSTRUCTION OF THE SELF IN SENECAN DRAMA
Authors: Fitch John , McElduff Siobhan
Published: July 2002

The characters of Senecan tragedy are more inward-looking than those of Greek tragedy. One aspect of their inwardness lies in their fierce attempts to define and assert identities for themselves, through their names, actions, family history, mythical precedents, social roles etc. These self-assertions are driven by desire in many forms, chiefly desire for recognition by others, and are closely connected with the tragic outcomes of the dramas. One section of the article is devoted to Oedipus, who insists on identifying with his guilty deeds despite his innocence of intention; another to Phaedra, who has multiple versions of herself and cannot choose between them.
COMPARISON: SOME SUGGESTIONS FOR IMPROVING THE INEVITABLE
Authors: Saler Benson
Published: July 2002

Schema theory and other facets of the cognitive sciences remind us that certain of the intellectual processes of the human brain are crucially comparative. In that comparison is ineluctable in monitoring the world and in coming to understand newly encountered events, then perhaps we can consciously improve on what is cognitively inevitable. It is suggested here that if we deliberately move from what the philosopher H.H. Price calls "the Philosophy of Universals" to what he terms "the Philosophy of Resemblances," our comparisons are likely to become more realistic, both existentially and cognitively. Further, in applying the Philosophy of Resemblances in both cross-cultural and cross-species comparisons, we may better tame the ethnocentric language of the former and the anthropocentric language of the latter in their respective efforts to transcend conceptualized boundaries in order to make comparisons.
OSÉE XII 2B À LA LUMIÈRE D'UN VASE D'ALBÂTRE DE L'ÉPOQUE DE SALMANASAR III (DJÉZIRÊH) ET LE RITUEL D'ALLIANCE ASSYRIEN. UNE HYPOTHÈSE DE LECTURE
Authors: Heintz Jean-Georges
Published: July 2002

En Os. xii 2b, le maintien du parallélisme poétique des deux stiques, bien que souvent méconnu, peut s'appuyer sur le témoignage iconographique d'un vase d'albâtre de l'époque de Salmanasar III, découvert récemment (1983) en Djézirêh : le décor de sa frise centrale y présente la même scène d''alliance' que la base du trône du même souverain au palais de Nimrud (vers 850 av. J.-C.), qui en constitue ainsi le 'modèle'. Sur la base de documents littéraires parallèles (vocabulaires d'Ébla; Enûma élis, tabl. VI, ll. 97-100; traité de succession d'Assarhaddon, ll. 153-156) est établi un dossier relatif à l'usage de l'huile en contexte d'alliance - notamment avec ce type de vase rituel - et à la pertinence de cette documentation pour la compréhension de ce passage prophétique.
FENGSHUI AND THE ENVIRONMENT OF SOUTHEAST CHINA
Authors: Luo Jun , He Xiaoxin
Published: July 2002

Literally translated as 'wind and water', Fengshui has been used as a special and important tool to harmonize people with their built environment and with the surrounding natural world. By examining some aspects of Fengshui as it was employed in traditional villages in southeast China, this paper aims to explore how Fengshui influences the interactions of Chinese people with their natural world. It focuses on two aspects of the employment of Fengshui in the outer spaces of villages in Southeast China: site selection and the entrance organisation. The methodology employed in the research involved both field investigation and archival study with a special emphasis on the historical records of family trees in the villages of Southeast China. Some modern psychological and architectural principles are borrowed as a frame of reference for analysing the Fengshui models. This analysis concludes that Fengshui satisfies not only physical needs, but also environmental, psychological and aesthetic ones. It demonstrates one of the most distinctive and sensitive treatments to aspects of the natural environment and landscape. It has been able, therefore, to improve the quality of the environment.
SONG CLUSTERING BY MEADOWLARKS: IS IT RELATED TO REPERTOIRE SIZE?
Authors: Lemon  , Falls  , Dickinson  , Perreault  , Tittler
Published: July 2002

Some birds with song repertoires sequentially associate (or cluster) songs of different types. That is, certain song types may occur together repeatedly, even on different days. We determined whether clustering of meadowlark songs correlated with repertoire size. We also tested whether clustered songs reflect either their structural similarities, or dissimilarities. Our data were obtained from recordings of free-living individuals of two meadowlark species, eastern, Sturnella magna , and western, S. neglecta . Eastern meadowlarks have approximately 10 times more song types per bird than do westerns. Therefore, if clustering is related to repertoire size, we predicted that there should be (1) proportionately more song clusters in eastern meadowlarks than in westerns, and (2) a similar correlation across individual birds within a species, especially so in easterns, which have a broader range of repertoire sizes. All 14 easterns examined showed clusters whereas only 5 of 11 westerns did so, and the easterns had proportionately more per bird. Many of the same clusters occurred in different recordings of individual easterns. In easterns, the extent of clustering as measured by a PCA analysis correlated strongly with estimated repertoire size. Clustered songs were neither more similar in structure, nor less so, than randomly-paired songs.
THE DEVELOPMENT OF LARVAL FORAGING BEHAVIOUR IN DROSOPHILA PAVANI, D. GAUCHA AND THEIR RECIPROCAL HYBRIDS
Authors: Del Pino Francisco , Godoy-Herrera Raúl
Published: July 2002

The development of larval foraging behaviour in the sibling species D. pavani and D. gaucha and in their reciprocal interspecific hybrids was analysed. The goals were: (i) to identify interspecific differences in developmental patterns of larval behavioural organization, and (ii) to study changes in the frequency of ecologically relevant behaviours during larval ontogeny. Hybridization changed the developmental pathway of feeding and locomotor activity, suggesting genetic divergence for foraging behaviour between the species. Larval turning and bending were not affected by hybridization, suggesting a similar genetic architecture for each of these activities in both species. Retreat and rearing were observed during the whole of larval period in D. pavani, while these behaviours were rarely observed in D. gaucha and the hybrids, suggesting dominance of the gaucha genome over that of pavani. The behavioural organization of D. pavani larvae is related to ontogeny; this was not observed in gaucha and in species hybrid larvae, suggesting again a dominance of this genome over that of D. pavani. The results are discussed in terms of evolutionary developmental genetics of foraging behaviour of Drosophila larvae.
DO JUVENILE YELLOW PERCH USE DIET CUES TO ASSESS THE LEVEL OF THREAT POSED BY INTRASPECIFIC PREDATORS?
Authors: Mirza Reehan , Chivers Douglas
Published: July 2002

The mechanisms that drive the evolution of intraspecifc predation (cannibalism) are unclear. Many authors speculate that predators can make substantial gains in nutrition and reproductive output by consuming conspecifics. However, by consuming conspecifics, predators may risk decreasing their inclusive fitness by consuming kin or increasing the chances of pathogen transmission. In fishes intraspecific predation is typically observed when resource levels are low. During these periods it is important for prey fishes to be able to accurately assess their level of predation risk from cannibalistic conspecifics. Prey animals may be able to do this by using chemical cues available in the predator's diet. The last meal consumed by the predator may give important information for prey animals to assess predation risk. We exposed juvenile yellow perch, Perca flavescens, to chemical cues of adult perch fed a diet of either juvenile perch, spot tail shiners, Notropis hudsonius, swordtails, Xiphophorus helleri, or a control of distilled water. Spot tail shiners and juvenile perch commonly form mixed species shoals and are vulnerable to the same suite of predators. Swordtails do not co-occur with yellow perch or spot tail shiners. We found that juvenile perch increased shelter use significantly more when exposed to chemical cues of adult perch fed juvenile perch or spot tails, compared to adult perch fed swordtails or those exposed to distilled water. This suggests that the level of chemosensory assessment used by juvenile perch is quite sophisticated and that the antipredator response can be mediated by specific cues in the predator's diet. This study is the first to demonstrate a response of a fish to chemical cues from intraspecific predators. Future studies should examine the importance of predator diet cues in responses to chemical cues from intraspecific predators.
EARLY PREDICTORS OF DOMINANCE ABILITY IN HEIFERS (BOS TAURUS, L.) OF THE HÉRENS BREED
Authors: Plusquellec  , Bouissou  , Pape G. Le
Published: July 2002

Many studies have looked for predictors of dominance in various species. However, to our knowledge only short term predictors have been investigated. Cows of the Hérens breed have been selected for fighting tendency and dominance ability; therefore these animals constitute an original and pertinent model to study the possibility of predicting dominance ability at an early age. Physical characteristics, several aspects of social behaviour, reactivity to fear eliciting situations, docility towards humans were assessed in 28 heifers at 6 and 18 months of age. These heifers were reared from birth in 5 permanent groups which never met. Dominance of the 28 subjects was estimated at 30 mo. by observing each heifer in a succession of seven groups that each contained 4 unacquainted animals. The 28 heifers were then allocated to 2 classes (dominant or subordinate) by means of a cluster analysis. Early indicators (combinations of variables) of adult dominance ability were assessed among the variables measured at 6 and 18 months, by a succession of linear discriminant analyses. The discriminant function which best predicts the dominance class either at 6 or 18 mo. includes mainly variables from the fear eliciting tests. This function allows accurate prediction of the dominant or subordinate position of heifers in 94.7 and 92.2% of the cases respectively. The less fearful a heifer was at either 6 or 18 months, the more dominant she tended to be at 30 months of age. These results are in accordance with the previously reported importance of emotional reactivity in dominance relationships in cattle.
EVIDENCE FOR THE EXISTENCE OF MOTHERING STYLES IN GUINEA PIGS (CAVIA APEREA F. PORCELLUS)
Authors: Albers  , Timmermans  , Vossen
Published: July 2002

Mothering styles are generally assumed to exist, in particular in the case of primates. However, an experimental procedure to ensure this assumption has been lacking and, moreover, mothering style was always defined post hoc . The short inter-birth interval and the possibility to cross-foster make the guinea pig a suitable species that has an advantage over primates for this type of study. The maternal behaviour of ten subjects was registered during mothering of four subsequent litters. To challenge a possible consistency of maternal behaviour two variables were manipulated: parentage (own young or adopted young) and the condition of the mothers (pregnant or non-pregnant). The concordances found suggest that behavioural parameters necessary to characterize a mothering style in guinea pigs should contain either locomotor, affiliative or aggressive behaviour. Other behavioural parameters were not found adequate for characterizing mothering styles. As significant concordances of maternal behaviour were found, in spite of the challenges offered, we conclude that guinea-pig mothers consistently differ from each other and hence that 'mothering styles' exist in guinea pigs.
ASSOCIATION BY MALE CHIMPANZEES: A SOCIAL TACTIC?
Authors: Newton-Fisher Nicholas
Published: July 2002

Whether and with whom to associate are possibly some of the most fundamental of choices faced by a chimpanzee, choices constrained by and dependent upon similar decisions made by potential association partners. Although much work has focused on the impact of ecological factors on the size of the temporary associations, or parties, it seems that chimpanzees, especially the males, form parties to gain social benefits, and that these benefits are dependent the particular composition of these parties. This paper examines the social determinates of the association patterns of male chimpanzees, members of the Sonso community in the Budongo Forest Reserve, western Uganda. Male chimpanzees showed clear preferences for association partners, and these partners had a strong tendency to associate in small parties. Strength of association within dyads accounted for a significant fraction of the variance in party size [all parties containing males: r2 = 0.30; male parties only: r2 = 0.24 (all dyads), r2 = 0 . 50 (dyads with positive associations only)]. These results supported the hypothesis that association was the result of tactical decisions, and refuted predictions of alternate hypotheses: random and passive (independent attraction to the same locations, such as fruiting trees) association. Further support for the tactical association hypothesis was provided by observations that association between males was flexible and that association patterns resolved into alternative association strategies, with some males shifting between strategies over time. The presence of cycling females influenced party size, which increased with the number present. The number of adult males in a party was also greater when cycling females were present, although remained similar whether one, two, three or four such females were in the party. Samples sizes for parties containing more than two cycling females were low, however. It is suggested that, for a Machiavellian primate in fission-fusion social system, the need to make decisions concerning association partners is cognitively demanding and may be an important, frequently used, function of the intelligence demonstrated by captive chimpanzees.
VARIATION OF SPERM PRECEDENCE IN THE ROVE BEETLE ALEOCHARA CURTULA (COLEOPTERA: STAPHYLINIDAE)
Authors: Benken  , Knaak  , Gack  , Eberle  , Peschke
Published: July 2002

In order to quantify the outcome of sperm competition in the mating system of the rove beetle Aleochara curtula we performed three different mating experiment series. Paternity was established by DNA fingerprinting with oligonucleotide probes. We found a precedence of the last male with a proportion of eggs fathered by the last male of 87% (median). Nevertheless, we observed a large variation of P2-values in A. curtula and cases of mixed paternity were documented as well as cases of 100% or 0% paternity of the last male. The variation of P2-values correlates with the efficiency of spermatophore and sperm transfer.
Comparative developmental studies using Oscheius/Dolichorhabditis sp. CEW1 (Rhabditidae)
Authors: Delattre Marie , Dichtel Marie-Laure , Félix Marie-Anne
Published: July 2002

In order to study the evolution of nematode vulva development, we focus on Oscheius/Dolichorhabditis sp. CEW1 (Rhabditidae) in comparison with Caenorhabditis elegans. In this species, the fates of the vulval precursor cells are determined by two successive nested inductions by the uterine anchor cell (instead of a single one in C. elegans). This hermaphroditic species can be cultured and handled like C. elegans. We review vulva development in this species. We present some molecular tools and the sequence of the Ras gene. This species is amenable to genetic analysis and we discuss the isolation of morphological markers. Afin d’étudier l’évolution du développement de la vulve des nématodes, nous nous concentrons sur l’espèce Oscheius/Dolichorhabditis sp. CEW1 (Rhabditidae) en la comparant à Caenorhabditis elegans. Dans cette espèce, les destinées des cellules précurseurs de la vulve sont déterminées par deux inductions emboîtées provenant de la cellule ancre de l’utérus (au lieu d’une seule chez C. elegans). Cette espèce hermaphrodite peut être élévée et manipulée comme C. elegans. Nous décrivons le développement de la vulve dans cette espèce. Nous présentons des outils moléculaires et la séquence du gène Ras. Les analyses génétiques sont possibles dans cette espèce et nous discutons l’isolement de marqueurs morphologiques.
Evolution of pyrophyllite particle sizes during dry grinding
Authors: Uhlík P. , Šucha V. , Eberl D. D. , Puškelová L'. , Čaplovičová M.
Published: July 2002

The Bertaut-Warren-Averbach (BWA) technique and high-resolution transmission electron microscopy (HRTEM) were used to characterize the products of dry-ground pyrophyllite. Mean crystallite thickness and crystallite thickness distributions were measured for each sample using the BWA technique. Mean crystallite thickness decreases during the treatment with respect to grinding time and energy applied per unit mass. The BWA data were checked by HRTEM measurements and good fits were obtained for samples having small mean particle thicknesses. Samples with thicker particles could not be measured properly by HRTEM because the number of particles counted from images is statistically insufficient. The shape of the crystallite and the particle-size distribution were used to determine the mechanism of pyrophyllite particle degradation. Particles initially having a lognormal size distribution are first delaminated randomly, then some are delaminated preferentially, thereby producing polymodal thickness distributions. Finally all particles undergo delamination yielding a lognormal thickness distribution.
A method of extending magnetic birefringence particle sizing into the sub-micron range
Authors: Wilson S. R. , Ridler P. J. , Jennings B. R.
Published: July 2002

Both magnetic and electric fields have been used to induce optical birefringence in colloidal suspen- sions. These have formed the bases of fast methods for measuring particle sizes and their distributions (Mekshenkov, 1965; Tsvetkov et al., 1975; O'Konski, 1976; Maret & Dransfeld, 1977; Stoylov, 1991; Jennings & Stoylov, 1992; Trusov & Vojtylov, 1993). Whereas the majority of studies have related to the electric-field procedure, we recently reported a magneto-optic procedure suitable for sizing magnetic particles (Wilson et al., 1996). By increasing the viscosity of the suspensions, we are now able to extend the size range down into the sub-micron region with relative ease. This note reports magnetic birefringence data for a montmorillonite sample and justifies the technique via supplementary data on vermiculite of greater size range.
Occurrence of fine chlorite (<0.2 µm) and its significance in the soils from the Ulsan area, Korea
Authors: Yeo S. J. , Kim S. J. , Bain D. C.
Published: July 2002

Well crystallized chlorite has been detected in a Typic Hapludult developed on quartz porphyry at Ulsan, Korea, after treatment of the <0.2 µm fraction with a high-gradient magnetic separation (HGMS) technique. The X-ray diffraction (XRD) characteristics of the chlorite suggest that it is an Fe-rich variety and this was confirmed by energy dispersive spectroscopy (EDS) analysis. The chlorite could not be detected with certainty in the <0.2 µm fraction but is clearly present throughout the soil profile in the <0.2 µm fraction. It is suggested that this chlorite is residual inherited chlorite, the rest of which has dissolved in the acidic environment (pH 4—5).
Mineralogical and chemical characteristics of five nontronites and Fe-rich smectites
Authors: Köster H. M. , Ehrlicher U. , Gilg H. A. , Jordan R. , Murad E. , Onnich K.
Published: July 2002

Five Fe–bearing dioctahedral smectites (three nontronites and two Fe-rich smectites) were purified using a variety of physical and chemical procedures. The structural formulae indicate one nontronite and one Fe-rich smectite to be montmorillonitic, whereas the other three smectites are beidellitic. Mössbauer spectra showed Fe to be exclusively trivalent and were fitted with three doublets, two of which had quadrupole splittings characteristic of Fe3+in octahedral coordination, whereas the third had a distinctly lower quadrupole splitting. Although the position of the Si–O stretching band in the infrared spectra could reflect tetrahedral Fe3+, the lack of distinctive features prevented a definitive attribution of this component to tetrahedral Fe3+. The18O/16O data suggest that fractionation of nontronite-water at ambient temperatures (1000 lnα = 23 ± 2‰) is lower than that of Fe-rich smectite (1000 lnα = 27 ± 2‰). The estimated formation temperatures of the samples are below 70°C.
Clinoferrosilite-bearing kelyphite: a breakdown product of xenolithic garnet, Delegate breccia pipes, New South Wales, Australia
Authors: Keankeo W. , Taylor W. R. , FitzGerald J. D.
Published: July 2002

Garnet pyroxenite xenoliths from the Delegate nephelinitic breccia pipes, New South Wales, Australia, contain relict garnets (py40 alm39 gr21) which are replaced by dark kelyphitic rims resulting from garnet breakdown. The kelyphite is composed of a lamellar intergrowth of secondary minerals, in which the lamellae are <1 μm in width. Analyses by SEM and ICPMS reveal that the kelyphite has an identical bulk chemical composition to the primary garnet. Kelyphitic rims on garnet are well known from xenoliths and xenocrysts in kimberlite pipes and from tectonically-uplifted mafic and ultramafic rocks in some metamorphic terranes. Orthopyroxene occurs in metamorphic kelyphites and it has been assumed that orthopyroxene is also the breakdown product of garnet transported in basic-ultrabasic magmas. However, TEM study of Delegate kelyphite shows that the ultrafine lamellae do not contain orthopyroxene but are instead composed of magnesian clinoferrosilite (En45Fs55), and lesser ferroan spinel and anorthite. The clinoferrosilite is probably the inversion product of initially-formed magnesian protoferrosilite. The breakdown reaction is believed to result from a sudden change to lower temperature and pressure conditions when the xenoliths were transported in the Delegate magma from ∼40 km depth to the surface.
Actual Fe-Li mica series as a series with ☐VI constant but not with AlIV or AlVI
Authors: Shihua Sun , Jie Yu
Published: July 2002

To date, Fe-Li micas have been defined differently from other micas. The purpose of this paper is to reinterpret the actual Fe-Li mica series with new concepts of ‘essential replacement’ (the evolution direction) and ‘composition track’ (the sequence of mica varieties). Two hundred and fifty-eight analyses from the literature are used for this study in the form of eight data groups. The common compositional and substitutional characters of Fe-Li micas have been reinterpreted in light of principal component analysis and a geometric frame of ideal Fe2+-Al-Li micas in space with (Si, AlIV, AlVI, Fe2+, Li, ☐VI, K)-coordinates.

In our new interpretation, the actual Fe-Li micas are essentially neither AlIV- nor AlVI-, but ☐VI-constant. The actual Fe-Li micas are the weakest fluctuant relative to the Annite-Polylithionite-Trilithionite-Siderophyllite (APTE) plane. About 90% of variations of actual Fe-Li micas range from the trioctahedral trend described as a sequence along the segment K2Al2Fe5/22+Li☐1/2Si6Al2O20(OH,F)4+x[AlFe−22+Li3SiAl−2] (−1/3≤ x≤5/8). The substitution AlFe−22+Li3SiAl−2 (i.e. 2AlIV +4Fe2+ → 2Si +AlVI +3Li) is the main mechanism that keeps actual Fe-Li micas trioctahedral. More than 8% of variations arise from the dioctahedral trend involving created AlVI- and ☐VI-increasing replacement. The actual Fe-Li mica series comprises the composition trend from Fe2+-biotite to lepidolite. This series is not on the siderophyllite-polylithionite join, but can be expressed ideally as K2Al1+xFe4−4x2+Li1+3x(Si6+2xAl2−2x) O20(OH,F)4 (−1/3 ≤x≤1).
Minor- and trace-element composition of trioctahedral micas: a review
Authors: Tischendorf G. , Förster H.-J. , Gottesmann B.
Published: July 2002

More than 19,000 analytical data mainly from the literature were used to study statistically the distribution patterns of F and the oxides of minor and trace elements (Ti, Sn, Sc, V, Cr, Ga, Mn, Co, Ni, Zn, Sr, Ba, Rb, Cs) in trioctahedral micas of the system phlogopite-annite/siderophyllite-polylithionite (PASP), which is divided here into seven varieties, whose compositional ranges are defined by the parameter mgli (= octahedral Mg minus Li). Plots of trace-element contents vs. mgli reveal that the elements form distinct groups according to the configuration of their distribution patterns. Substitution of most of these elements was established as a function of mgli. Micas incorporate the elements in different abundances of up to four orders of magnitude between the concentration highs and lows in micas of ‘normal’ composition. Only Zn, Sr and Sc are poorly correlated to mgli. In compositional extremes, some elements (Zn, Mn, Ba, Sr, Cs, Rb) may be enriched by up to 2–3 orders of magnitude relative to their mean abundance in the respective mica variety. Mica/melt partition coefficients calculated for Variscan granites of the German Erzgebirge demonstrate that trace-element partitioning is strongly dependent on the position of the mica in the PASP system, which has to be considered in petrogenetic modelling.

This review indicates that for a number of trace elements, the concentration ranges are poorly known for some of the mica varieties, as they are for particular host rocks (i.e. igneous rocks of A-type affiliation). The study should help to develop optimal analytical strategies and to provide a tool to distinguish between micas of ‘normal’ and ‘abnormal’ trace-element composition.
Transmission electron microscopic study of new, regular, mixed-layer structures in calcium-rare-earth fluorocorbonote minerals
Authors: Xiuling Wu , Dawei Meng , Zhaolu Pan , Guangming Yang , Douxing Li
Published: July 2002

Structures of calcium-rare-earth (Ca-RE) fluorocarbonate minerals from southwest China have been investigated using selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). They are described as combinations of layers of bastnäsite-(Ce), CeFCO3 (B layers), and synchysite-(Ce), CeFCO3·CaCO3 (S layers) (Donnay and Donnay, 1953). We report here the discovery of six new, regular, mixed-layer structures in parisite-(Ce) observed using SAED and HRTEM. The symmetry, cell parameters, chemical formulae and stacking of the structural unit layers, etc., were determined for each. The regular, mixed-layer structures are formed by stacking unit layers of bastnäsite-(Ce) and synchysite-(Ce) in varying proportions along the c axis. HRTEM shows that there are different distribution modes for the Ce-F ion layers, the CO3 ion groups between the Ce-F ion layers and the CO3 ion groups between the Ce-F and Ca ion layers. The minerals may be regarded as polymorphs with the same chemical composition and the same spacing of the unit layers, but different arrangements of ion layers in the structural unit layers and different stacking sequences of the structural unit layers.
Laser-induced time-resolved luminescence of rare-earth elements in scheelite
Authors: Gaft M. , Panczer G. , Uspensky E. , Reisfeld R.
Published: July 2002

Natural and synthetic scheelite are investigated by time-resolved laser-induced luminescence to detect and ascribe various luminescence lines to a variety of REE. The selectivity of detection is possible by using different time delays after excitation, different gate widths and different excitation wavenumbers and allowed to detect REE in samples where they are hidden by intrinsic luminescence and not visible in the steady-state spectra as well as by cathodoluminescenee. Luminescence of Pr3+, Er3+ and Tm3+ are detected even with low concentrations and in the presence of Tb3+, Dy3+ and Sm3+. Luminescence of Ho3+ and Yb3+ is firstly detected in natural scheelites and luminescence of Eu2+ and Ce3+ is preliminary suggested.
Differential REE uptake by sector growth of monazite
Authors: Cressey G. , Wall F. , Cressey B. A.
Published: July 2002

Monazite-(Ce) from a dolomite carbonatite at Kangankunde, Malawi, is
sector-zoned with variation in La2O3 of
up to 6.0 wt.% and in Nd2O3 of up to 3.9
wt.% between sectors. Single crystal X-ray diffraction, backscattered electron
imaging and microprobe analysis have been used to establish the relationship
between the morphology and sector chemistry of this low-Th monazite,
(Ce,La,Nd)PO4. Uptake of La by {011} sector surfaces is
enhanced relative to that of and {100} sectors; Ce shows no
partitioning differences; and uptake of Nd is more easily facilitated on
and {100} surfaces relative to
{011}. There appears to be a distinct relationship between the size of the
REE ion and the probability of uptake
via the different growth surfaces. Interpretation of
this uptake behaviour, based on theories involving ‘protosites’, involves an
investigation of the possible kink site geometries at edge-steps during growth.
Part-formed kink sites with small entrance sizes are calculated to occur with
higher frequency on relative to {011}, and this
correlates with an increase in the smaller-sized REE
(Nd) uptake by growth surfaces. The overall
morphology and sector growth is suggested to be a function of uptake
chemistry.
Systemic delivery of an adenoviral vector encoding canine factor VIII results in short-term phenotypic correction, inhibitor development, and biphasic liver toxicity in hemophilia A dogs
Authors: Gallo-Penn Angela M. , Shirley Pamela S. , Andrews Julie L. , Tinlin Shawn , Webster Sandy , Cameron Cherie , Hough Christine , Notley Colleen , Lillicrap David , Kaleko Michael , Connelly Sheila
Published: July 2002

Canine hemophilia A closely mimics the human disease and has been used previously in the development of factor VIII (FVIII) protein replacement products. FVIII-deficient dogs were studied to evaluate an in vivo gene therapy approach using an E1/E2a/E3-deficient adenoviral vector encoding canine FVIII. Results demonstrated a high level of expression of the canine protein and complete phenotypic correction of the coagulation defect in all 4 treated animals. However, FVIII expression was short-term, lasting 5 to 10 days following vector infusion. All 4 dogs displayed a biphasic liver toxicity, a transient drop in platelets, and development of anticanine FVIII antibody. Canine FVIII inhibitor development was transient in 2 of the 4 treated animals. These data demonstrate that systemic delivery of attenuated adenoviral vectors resulted in liver toxicity and hematologic changes. Therefore, the development of further attenuated adenoviral vectors encoding canine FVIII will be required to improve vector safety and reduce the risk of immunologic sequelae, and may allow achievement of sustained phenotypic correction of canine hemophilia A.
Dipyridamole inhibits sickling-induced cation fluxes in sickle red blood cells
Authors: Joiner Clinton H. , Jiang Maorong , Claussen William J. , Roszell Nancy J. , Yasin Zahida , Franco Robert S.
Published: July 2002

Sickling-induced cation fluxes contribute to cellular dehydration of sickle red blood cells (SS RBCs), which in turn potentiates sickling. This study examined the inhibition by dipyridamole of the sickling-induced fluxes of Na+, K+, and Ca++ in vitro. At 2% hematocrit, 10 μM dipyridamole inhibited 65% of the increase in net fluxes of Na+ and K+ produced by deoxygenation of SS RBCs. Sickle-induced Ca++ influx, assayed as 45Ca++uptake in quin-2–loaded SS RBCs, was also partially blocked by dipyridamole, with a dose response similar to that of Na+and K+ fluxes. In addition, dipyridamole inhibited the Ca++-activated K+ flux (via the Gardos pathway) in SS RBCs, measured as net K+ efflux in oxygenated cells exposed to ionophore A23187 in the presence of external Ca++, but this effect resulted from reduced anion conductance, rather than from a direct effect on the K+channel. The degree of inhibition of sickling-induced fluxes was dependent on hematocrit, and up to 30% of dipyridamole was bound to RBC membranes at 2% hematocrit. RBC membrane content of dipyridamole was measured fluorometrically and correlated with sickling-induced flux inhibition at various concentrations of drug. Membrane drug content in patients taking dipyridamole for other clinical indications was similar to that producing inhibition of sickling-induced fluxes in vitro. These data suggest that dipyridamole might inhibit sickling-induced fluxes of Na+, K+, and Ca++ in vivo and therefore have potential as a pharmacological agent to reduce SS RBC dehydration.