bluuebunny/crossref_metadata_2025 huggingface dataset:
HIGH-DIELECTRIC CONSTANT THIN FILMS FOR DYNAMIC RANDOM ACCESS MEMORIES (DRAM)
Authors: Scott J. F.
Published: July 2002

▪ Abstract  We discuss high-dielectric films, in general, oxide ferroelectrics based on simple perovskite structures and related Aurivillius-phase layered structure perovskites employed as thin-film capacitors in dynamic random access memories (DRAMs). Emphasis is on breakdown mechanisms and limits, leakage currents, electrodes and electrode interfaces, scaling to submicron geometries, and deposition techniques.
DYNAMICAL SUPERSYMMETRY BREAKING
Authors: Poppitz Erich , Trivedi Sandip P.
Published: July 2002

▪ Abstract  Dynamical supersymmetry breaking is a fascinating theoretical problem that is also of phenomenological significance. A better understanding of this phenomenon can help in model building, which in turn is useful in guiding the search for supersymmetry. This article reviews recent developments in the field, discussing a few examples to illustrate the main ideas. In the process, we show how the techniques of holomorphy and duality come into play and how they have helped in the study of gauge-mediated supersymmetry breaking. The review is intended for readers with a prior knowledge of supersymmetry who want to find out about the recent progress in this field.
MULTIPHONON GIANT RESONANCES IN NUCLEI
Authors: Aumann T. , Bortignon P. F. , Emling H.
Published: July 2002

▪ Abstract  We review the present knowledge of multiphonon giant resonances in nuclei. Theoretical concepts approaching the intrinsic structure and excitation mechanisms of multiphonon states are discussed. The available experimental results are summarized, including a brief description of applied techniques. This review emphasizes electromagnetic excitations of double dipole resonances. Open questions and possible routes toward a solution are addressed.
PRESYNAPTIC RECEPTORS
Authors: Miller Richard J.
Published: July 2002

▪ Abstract  Activation of different types of G-protein-linked and ionotropic presynaptic receptors has been shown to regulate neurotransmitter release throughout the central and peripheral nervous systems. In the case of G-protein-linked receptors, three major mechanisms have been suggested: (a) inhibition of Ca channels in the nerve terminal; (b) the activation of presynaptic K channels, resulting in a reduction in the effectiveness of the action potential; and (c) direct modulation of one or more components of the neurotransmitter vesicle release apparatus. In the case of ionotropic presynaptic receptors, inhibition of release may be achieved through depolarization of the terminal and inactivation of Na and Ca channels. Activation of presynaptic ionotropic receptors that are appreciably Ca permeable can also enhance the release of transmitters as a result of their ability to raise [Ca]i in the terminal directly. Many transmitters employ several of these mechanisms, thus allowing considerable flexibility in the presynaptic regulation of transmitter release.
Drug Treatment Effects on Disease Progression
Authors: Chan PLS , Holford NHG
Published: July 2002

Degenerative diseases are characterized by a worsening of disease status over time. The rate of deterioration is determined by the natural rate of progression of the disease and by the effect of drug treatments. A goal of drug treatment is to slow disease progression. Drug treatments can be categorized as symptomatic or protective. Symptomatic treatments do not affect the rate of disease progression whereas protective treatments have the ability to slow disease progression down. Many current methods for describing disease progression have two common drawbacks: a linear relationship between time and disease status is assumed, and within- and between-subject variability is ignored. Disease progress models combined with pharmacokinetic pharmacodynamic models and hierarchical random effects statistical models provide insights into understanding the time course and management of degenerative disease.
MOLECULES IN HIGH RYDBERG STATES
Authors: Merkt F.
Published: July 2002

▪ Abstract  The unusual properties of high molecular Rydberg states with principal quantum number [Formula: see text] have enabled the development of new research tools for the study of molecules and ions in the gas phase. These tools range from spectroscopic techniques such as zero kinetic energy (ZEKE) photoelectron spectroscopy and mass-analyzed threshold ionization (MATI) spectroscopy to techniques that are suited to the investigation of photodissociation processes, bimolecular reactions, and state-selected ion-molecule reactions. This review summarizes recent progress in the understanding of the properties of high molecular Rydberg states and gives an overview of recent chemical applications of these states.
SPECTROSCOPY OF METAL ION COMPLEXES: Gas-Phase Models for Solvation
Authors: Duncan Michael A.
Published: July 2002

▪ Abstract  Weakly bound metal ion complexes are produced in molecular beams and studied with mass-selected laser photodissociation spectroscopy. The metal ions Mg+ and Ca+ are the focus of these studies because they have a single valence electron and strong atomic resonance lines in convenient wavelength regions. Weakly bound complexes of these ions with rare-gas atoms and small molecules are prepared with laser vaporization in a pulsed nozzle cluster source. The vibrationally and rotationally resolved electronic spectra obtained for these complexes help to determine the complexes' structures and bonding energetics. Observations from these studies have provided many new insights into the fundamental interactions in electrostatic bonding.
Antifreeze Proteins of Teleost Fishes
Authors: Fletcher Garth L , Hew Choy L , Davies Peter L
Published: July 2002

▪ Abstract  Marine teleosts at high latitudes can encounter ice-laden seawater that is approximately 1°C colder than the colligative freezing point of their body fluids. They avoid freezing by producing small antifreeze proteins (AFPs) that adsorb to ice and halt its growth, thereby producing an additional non-colligative lowering of the freezing point. AFPs are typically secreted by the liver into the blood. Recently, however, it has become clear that AFP isoforms are produced in the epidermis (skin, scales, fin, and gills) and may serve as a first line of defense against ice propagation into the fish. The basis for the adsorption of AFPs to ice is something of a mystery and is complicated by the extreme structural diversity of the five antifreeze types. Despite the recent acquisition of several AFP three-dimensional structures and the definition of their ice-binding sites by mutagenesis, no common ice-binding motif or even theme is apparent except that surface-surface complementarity is important for binding. The remarkable diversity of antifreeze types and their seemingly haphazard phylogenetic distribution suggest that these proteins might have evolved recently in response to sea level glaciation occurring just 1–2 million years ago in the northern hemisphere and 10–30 million years ago around Antarctica. Not surprisingly, the expression of AFP genes from different origins can also be quite dissimilar. The most intensively studied system is that of the winter flounder, which has a built-in annual cycle of antifreeze expression controlled by growth hormone (GH) release from the pituitary in tune with seasonal cues. The signal transduction pathway, transcription factors, and promoter elements involved in this process are just beginning to be characterized.
Function of Surfactant Proteins B and C
Authors: Weaver Timothy E , Conkright Juliana Johnson
Published: July 2002

▪ Abstract  SP-B is the only surfactant-associated protein absolutely required for postnatal lung function and survival. Complete deficiency of SP-B in mice and humans results in lethal, neonatal respiratory distress syndrome and is characterized by a virtual absence of lung compliance, highly disorganized lamellar bodies, and greatly diminished levels of SP-C mature peptide; in contrast, lung structure and function in SP-C null mice is normal. This review attempts to integrate recent findings in humans and transgenic mice with the results of in vitro studies to provide a better understanding of the functions of SP-B and SP-C and the structural basis for their actions.
PLANT VIRUS GENE VECTORS FOR TRANSIENT EXPRESSION OF FOREIGN PROTEINS IN PLANTS
Authors: Scholthof Herman B. , Scholthof Karen-Beth G. , Jackson Andrew O.
Published: July 2002

▪ Abstract  The development of plant virus gene vectors for expression of foreign genes in plants provides attractive biotechnological tools to complement conventional breeding and transgenic methodology. The benefits of virus-based transient RNA and DNA replicons versus transgenic gene expression include rapid and convenient engineering coupled with flexibility for expeditious application in various plant species. These characteristics are especially advantageous when very high levels of gene expression are desired within a short time, although instability of the foreign gene in the viral genome can present some problems. The strategies that have been tested for foreign gene expression in various virus-based vectors include gene replacement, gene insertion, epitope presentation, use of virus controlled gene expression cassettes, and complementation. Recent reports of the utililization of virus vectors for foreign gene expression in fundamental research and biotechnology applications are discussed.
ROLE OF PLANT PATHOLOGY IN INTEGRATED PEST MANAGEMENT
Authors: Jacobsen Barry J.
Published: July 2002

▪ Abstract  Integrated Pest Management (IPM) is a paradigm that is widely adopted by all pest control disciplines but whose early definitions and philosophical basis belong to entomologists. Plant pathology research and extension work has historically emphasized integration of several control strategies and fits both historical and modern definitions of IPM. While the term IPM has been used only sparingly in the phytopathology literature, the integrated disease management strategies emphasized are now considered to be at the forefront of ecologically based or biointensive pest management. While IPM is broadly endorsed by crop protection disciplines, farmers, other agriculturalists, and consumers, the potential for Integrated Pest Management has not been fully realized. Most IPM programs reflect a package of tools and decision aids for individual crop insect, weed, nematode, and plant disease management. IPM programs that integrate all types of pests with the agroecosystem, crop growth and loss models still await the formation of interdisciplinary teams focusing on growers needs. Lack of funding for both discipline and interdisciplinary developmental research and implementation is responsible for the paucity of comprehensive IPM programs for the majority of the U.S. crop acreage. This review explores the origins and evolution of the IPM paradigm and reviews efforts to achieve the body of knowledge and implementation structure to achieve IPM's full potential.
TAXONOMY ANDIDENTIFICATION OFSEPTORIAANDSTAGONOSPORASPECIES ONSMALL-GRAINCEREALS
Authors: Cunfer Barry M , Ueng Peter P
Published: July 2002

▪ Abstract  Numerous significant changes have been made in the taxonomy of both the anamorphs and teleomorphs of the Septoria group of leaf spot pathogens on small grain cereals during the past 30 years. The pathogens fall into two related but distinct groups, with anamorphic genera now placed in Septoria and Stagonospora of the Sphaeropsidales. Each of these genera has distinct teleomorphs in the Loculoascomycetes in Mycosphaerella and Phaeosphaeria. These reclassifications were based largely on fungal morphology and host pathogenicity as originally characterized. Recent studies have investigated the phylogenetic relationships among these species using the techniques of molecular genetics, and have related molecular characteristics to taxonomy based on classical morphology. A clearer understanding of the taxonomy of this group will enhance our ability to diagnose and manage these important cereal pathogens.
Nematode Parasitism Genes
Authors: Davis Eric L. , Hussey Richard S. , Baum Thomas J. , Bakker Jaap , Schots Arjen , Rosso Marie-Noëlle , Abad Pierre
Published: July 2002

The ability of nematodes to live on plant hosts involves multiple parasitism genes. The most pronounced morphological adaptations of nematodes for plant parasitism include a hollow, protrusible stylet (feeding spear) connected to three enlarged esophageal gland cells that express products that are secreted into plant tissues through the stylet. Reverse genetic and expressed sequence tag (EST) approaches are being used to discover the parasitism genes expressed in nematode esophageal gland cells. Some genes cloned from root-knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes have homologues reported in genomic analyses of Caenorhabditis elegans and animal-parasitic nematodes. To date, however, the candidate parasitism genes endogenous to the esophageal glands of plant nematodes (such as the ß-1,4-endoglucanases) have their greatest similarity to microbial genes, prompting speculation that genes for plant parasitism by nematodes may have been acquired by horizontal gene transfer.
THE DECAY AND BREAKDOWN OF COMMUNIST ONE-PARTY SYSTEMS
Authors: Kalyvas Stathis N.
Published: July 2002

▪ Abstract  The failure to anticipate the collapse of communist one-party systems stands in striking contrast to the determinism of retrospective accounts. This essay reviews accounts of the decay and breakdown of one-party systems in order to uncover the causes behind political science's inability to both anticipate these developments and provide satisfactory explanations. These causes include the deterministic character of most accounts, the absence of a theory of single-party rule, the absence or misspecification of causal links between the major building blocks of the arguments put forth, and the analytic conflation of decay and breakdown. Understanding the decay and breakdown of one-party systems requires a methodologically conscious distinction between these two processes and a specification of their links (and the links between the variables affecting each process), grounded in a theory of single-party rule.
DEMOCRATICINSTITUTIONS ANDREGIMESURVIVAL: Parliamentary and Presidential Democracies Reconsidered
Authors: Cheibub José Antonio , Limongi Fernando
Published: July 2002

▪ Abstract  We review arguments and empirical evidence in the comparative literature that bear on the differences in the survival rates of parliamentary and presidential democracies. Most of these arguments focus on the fact that presidential democracies are based on the separation of executive and legislative powers, whereas parliamentary democracies are based on the fusion of these powers. The implications of this basic distinction lead to radically different behavior and outcomes under each regime. We argue that this perspective is misguided and that one cannot deduce the functioning of the political system from the way governments are formed. Other provisions, constitutional and otherwise, also affect the way parliamentary and presidential democracies operate, and these provisions may counteract some of the tendencies that we would expect to observe if we derived the regime's performance from its basic constitutional principle.
Baby and The Brain: Advances in Child Development
Authors: DiPietro Janet A.
Published: July 2002

▪ Abstract  As child morbidity and mortality declined during the twentieth century, a corresponding increase occurred in the relevance of child psychological well-being to public health. Evidence of this trend is the proliferation of programs intended to ameliorate conditions that place children in jeopardy of poor developmental outcome. Most recently, neurobiologic information on brain function and structure has been used to promote strategies for optimizing child development. This review will evaluate the current state of knowledge relating early child development to brain research and illustrate the potential misuse of this information. It will also suggest the following: (a) the extrapolation of neuroscience results to early academic and social enrichment programs obscures the magnitude of potential effects of these programs relative to the vast burden of risk imposed by poverty, and (b) an emphasis on intellectual functioning misses the most compelling evidence on the role of the early social environment in mediating establishment of neural networks that regulate a child's response to stress and capacity for self-control.
Artistic and Psychological Experiments with Synesthesia
Authors: Campen Crétien van
Published: July 2002

Artists and psychologists have been experimenting with synesthesia for centuries. The author provides a historical review to show that artists and psychologists have always had great difficulty manipulating and controlling the phenomenon of synesthesia. Within these limits, artistic experiments with color organs, musical paintings and visual music have primarily uncovered perceptual and emotional aspects of synesthesia. Psychological experiments have produced a variety of methodologies to aid the study of synesthesia. Currently, psychologists approach synesthesia foremost as a neurological phenomenon, while artists generally explore digital devices to simulate synesthesia.
Impersonal se Constructions in Romance and the Passivization of Unergatives
Authors: Dobrovie-Sorin Carmen
Published: July 2002

Romance constructions of the type SE Vunerg (e.g., si dorme) are shown to rely not only on nominative SE, as in Italian finite clauses, but also on accusative middle-passive SE. The latter analysis is needed for Romanian, because this language does not have nominative SE, as well as for Italian nonfinite clauses, in which nominative SE is illegitimate. According to my restatement of Cinque's (1988) generalizations, [+/−1arg] features are not needed. I assume a constrained theory of passivization, according to which the suspended Agent role cannot surface in the syntax as either -en or SE. The passivization of unergatives depends on analyzing unergatives as transitives with null cognate objects.
Integrating Prosodic and Lexical Cues for Automatic Topic Segmentation
Authors: Tür Gökhan , Hakkani-Tür Dilek , Stolcke Andreas , Shriberg Elizabeth
Published: July 2002

We present a probabilistic model that uses both prosodic and lexical cues for the automatic segmentation of speech into topically coherent units. We propose two methods for combining lexical and prosodic information using hidden Markov models and decision trees. Lexical information is obtained from a speech recognizer, and prosodic features are extracted automatically from speech waveforms. We evaluate our approach on the Broadcast News corpus, using the DARPA-TDT evaluation metrics. Results show that the prosodic model alone is competitive with word-based segmentation methods. Furthermore, we achieve a significant reduction in error by combining the prosodic and word-based knowledge sources.
Electrophysiological Signatures of Visual Lexical Processing: Open-and Closed-Class Words
Authors: Brown Colin M. , Hagoort Peter , Keurs Mariken ter
Published: July 2002

n This paper presents evidence of the disputed existence of an electrophysiological marker for the lexical-categorical distinction between open-and closed-class words. Event-related brain potentials were recorded from the scalp while subjects read a story. Separate waveforms were computed for open-and closed-class words. Two aspects of the waveforms could be reliably related to vocabulary class. The first was an early negativity in the 230-to 350-msec epoch, with a bilateral anterior predominance. This negativity was elicited by open-and closed-class words alike, was not affected by word frequency or word length, and had an earlier peak latency for closed-class words.

The second was a frontal slow negative shift in the 350-to 500-msec epoch, largest over the left side of the scalp. This late negativity was only elicited by closed-class words. Although the early negativity cannot serve as a qualitative marker of the open-and closed-class distinction, it does reflect the earliest electrophysiological manifestation of the availability of categorical information from the mental lexicon. These results suggest that the brain honors the distinction between open-and closed-class words, in relation to the different roles that they play in on-line sentence processing.
On the Computational Power of Winner-Take-All
Authors: Maass Wolfgang
Published: July 2002

This article initiates a rigorous theoretical analysis of the computational power of circuits that employ modules for computing winner-take-all. Computational models that involve competitive stages have so far been neglected in computational complexity theory, although they are widely used in computational brain models, artificial neural networks, and analog VLSI. Our theoretical analysis shows that winner-take-all is a surprisingly powerful computational module in comparison with threshold gates (also referred to as McCulloch-Pitts neurons) and sigmoidal gates. We prove an optimal quadratic lower bound for computing winner-takeall in any feedforward circuit consisting of threshold gates. In addition we show that arbitrary continuous functions can be approximated by circuits employing a single soft winner-take-all gate as their only nonlinear operation.

Our theoretical analysis also provides answers to two basic questions raised by neurophysiologists in view of the well-known asymmetry between excitatory and inhibitory connections in cortical circuits: how much computational power of neural networks is lost if only positive weights are employed in weighted sums and how much adaptive capability is lost if only the positive weights are subject to plasticity.
Reclassification as Supervised Clustering
Authors: Sierra A. , Corbacho F.
Published: July 2002

In some branches of science, such as molecular biology, classes may be defined but not completely trusted. Sometimes posterior analysis proves them to be partially incorrect. Despite its relevance, this phenomenon has not received much attention within the neural computation community. We define reclassification as the task of redefining some given classes by maximum likelihood learning in a model that contains both supervised and unsupervised information. This approach leads to supervised clustering with an additional complexity penalizing term on the number of new classes. As a proof of concept, a simple reclassification algorithm is designed and applied to a data set of gene sequences. To test the performance of the algorithm, two of the original classes are merged. The algorithm is capable of unraveling the original three-class hidden structure, in contrast to the unsupervised version (K-means); moreover, it predicts the subdivision of one of the original classes into two different ones.
A Silicon Implementation of the Fly's Optomotor Control System
Authors: Harrison Reid R. , Koch Christof
Published: July 2002

Flies are capable of stabilizing their body during free flight by using visual motion information to estimate self-rotation. We have built a hardware model of this optomotor control system in a standard CMOS VLSI process. The result is a small, low-power chip that receives input directly from the real world through on-board photoreceptors and generates motor commands in real time. The chip was tested under closed-loop conditions typically used for insect studies. The silicon system exhibited stable control sufficiently analogous to the biological system to allow for quantitative comparisons.
Multidimensional Encoding Strategy of Spiking Neurons
Authors: Eurich Christian W. , Wilke Stefan D.
Published: July 2002

Neural responses in sensory systems are typically triggered by a multitude of stimulus features. Using information theory, we study the encoding accuracy of a population of stochastically spiking neurons characterized by different tuning widths for the different features. The optimal encoding strategy for representing one feature most accurately consists of narrow tuning in the dimension to be encoded, to increase the single-neuron Fisher information, and broad tuning in all other dimensions, to increase the number of active neurons. Extremely narrow tuning without sufficient receptive field overlap will severely worsen the coding. This implies the existence of an optimal tuning width for the feature to be encoded. Empirically, only a subset of all stimulus features will normally be accessible. In this case, relative encoding errors can be calculated that yield a criterion for the function of a neural population based on the measured tuning curves.
A Spike-Train Probability Model
Authors: Kass Robert E. , Ventura Valérie
Published: July 2002

Poisson processes usually provide adequate descriptions of the irregularity in neuron spike times after pooling the data across large numbers of trials, as is done in constructing the peristimulus time histogram. When probabilities are needed to describe the behavior of neurons within individual trials, however, Poisson process models are often inadequate. In principle, an explicit formula gives the probability density of a single spike train in great generality, but without additional assumptions, the firing-rate intensity function appearing in that formula cannot be estimated. We propose a simple solution to this problem, which is to assume that the time at which a neuron fires is determined probabilistically by, and only by, two quantities: the experimental clock time and the elapsed time since the previous spike. We show that this model can be fitted with standard methods and software and that it may used successfully to fit neuronal data.
A Theory for Learning by Weight Flow on Stiefel-Grassman Manifold
Authors: Fiori Simone
Published: July 2002

Recently we introduced the concept of neural network learning on Stiefel-Grassman manifold for multilayer perceptron—like networks. Contributions of other authors have also appeared in the scientific literature about this topic. This article presents a general theory for it and illustrates how existing theories may be explained within the general framework proposed here.
Nonlinear Time-Series Prediction with Missing and Noisy Data
Authors: Tresp Volker , Hofmann Reimar
Published: July 2002

We derive solutions for the problem of missing and noisy data in nonlinear time-series prediction from a probabilistic point of view. We discuss different approximations to the solutions—in particular, approximations that require either stochastic simulation or the substitution of a single estimate for the missing data. We show experimentally that commonly used heuristics can lead to suboptimal solutions. We show how error bars for the predictions can be derived and how our results can be applied to K-step prediction. We verify our solutions using two chaotic time series and the sunspot data set. In particular, we show that for K-step prediction, stochastic simulation is superior to simply iterating the predictor.
Correlations Without Synchrony
Authors: Brody Carlos D.
Published: July 2002

Peaks in spike train correlograms are usually taken as indicative of spike timing synchronization between neurons. Strictly speaking, however, a peak merely indicates that the two spike trains were not independent. Two biologically plausible ways of departing from independence that are capable of generating peaks very similar to spike timing peaks are described here: covariations over trials in response latency and covariations over trials in neuronal excitability. Since peaks due to these interactions can be similar to spike timing peaks, interpreting a correlogram may be a problem with ambiguous solutions. What peak shapes do latency or excitability interactions generate? When are they similar to spike timing peaks? When can they be ruled out from having caused an observed correlogram peak? These are the questions addressed here. The previous article in this issue proposes quantitative methods to tell cases apart when latency or excitability covariations cannot be ruled out.
Hawai'i's “Local” Theatre
Authors: Carroll Dennis
Published: July 2002

Hawaiian “local” theatre—for residents, not tourists—is usually set in Hawai'i, uses Hawaiian and pidgin, and explores the culture and lifestyle of the many ethnic groups that comprise Hawai'i. This local theatre originated early in the 20th century, but has been thriving even more recently.
Introduction: Hijikata Tatsumi: The Words of Butoh
Authors: Nanako Kurihara
Published: July 2002

For the first time in English, we present many of Hijikata's aesthetic and poetic texts. These texts are put into context by Kurihara Nanako's introductory essay. The section includes an interview with Hijikata and a conversation between Hijikata and Japanese experimental theatre innovator Suzuki Tadashi.

Hijikata Tatsumi died in 1986, but his impact on Japanese and world performance remains strong. One of the founders of butoh, Hijikata's dances were “blistering images of emaciation and death”, yet beautiful.
Constructive Genetic Algorithm for Clustering Problems
Authors: Lorena Luiz Antonio Nogueira , Furtado João Carlos
Published: July 2002

Genetic algorithms (GAs) have recently been accepted as powerful approaches to solving optimization problems. It is also well-accepted that building block construction (schemata formation and conservation) has a positive influence on GA behavior. Schemata are usually indirectly evaluated through a derived structure. We introduce a new approach called the Constructive Genetic Algorithm (CGA), which allows for schemata evaluation and the provision of other new features to the GA. Problems are modeled as bi-objective optimization problems that consider the evaluation of two fitness functions. This double fitness process, called fg-fitness, evaluates schemata and structures in a common basis. Evolution is conducted considering an adaptive rejection threshold that contemplates both objectives and attributes a rank to each individual in population. The population is dynamic in size and composed of schemata and structures. Recombination preserves good schemata, and mutation is applied to structures to get population diversification. The CGA is applied to two clustering problems in graphs. Representation of schemata and structures use a binary digit alphabet and are based on assignment (greedy) heuristics that provide a clearly distinguished representation for the problems. The clustering problems studied are the classical p-median and the capacitated p-median. Good results are shown for problem instances taken from the literature.
Pattern Formation and Optimization in Army Ant Raids
Authors: Solé Ricard V. , Bonabeau Eric , Delgado Jordi , Fernández Pau , Marín Jesus
Published: July 2002

Army ant colonies display complex foraging raid patterns involving thousands of individuals communicating through chemical trails. In this article we explore, by means of a simple search algorithm, the properties of these trails in order to test the hypothesis that their structure reflects an optimized mechanism for exploring and exploiting food resources. The raid patterns of three army ant species, Eciton hamatum, Eciton burchelli, and Eciton rapax, are analyzed. The respective diets of these species involve large but rare, small but common, and a combination of large but rare and small but common food sources. Using a model proposed by Deneubourg et al. [4], we simulate the formation of raid patterns in response to different food distributions. Our results indicate that the empirically observed raid patterns maximize return on investment, that is, the amount of food brought back to the nest per unit of energy expended, for each of the diets. Moreover, the values of the parameters that characterize the three optimal pattern-generating mechanisms are strikingly similar. Therefore the same behavioral rules at the individual level can produce optimal colony-level patterns. The evolutionary implications of these findings are discussed.
Self-Replicating Structures: Evolution, Emergence, and Computation
Authors: Reggia James A. , Lohn Jason D. , Chou Hui-Hsien
Published: July 2002

Since von Neumann's seminal work around 1950, computer scientists and others have studied the algorithms needed to support self-replicating systems. Much of this work has focused on abstract logical machines (automata) embedded in two-dimensional cellular spaces. This research was motivated by the desire to understand the basic information-processing principles underlying self-replication, the potential long-term applications of programmable self-replicating machines, and the possibility of gaining insight into biological replication and the origins of life. We view past research as taking three main directions: early complex universal computer-constructors modeled after Turing machines, qualitatively simpler self-replicating loops, and efforts to view self-replication as an emergent phenomenon. We discuss our recent studies in the latter category showing that self-replicating structures can emerge from nonreplicating components, and that genetic algorithms can be applied to program automatically simple but arbitrary structures to replicate. We also describe recent work in which self-replicating structures are successfully programmed to do useful problem solving as they replicate. We conclude by identifying some implications and important research directions for the future.
Institutionalization of Life‐Cycle Thinking in the Everyday Discourse of Market Actors
Authors: Heiskanen Eva
Published: July 2002

The widespread popularity of life‐cycle assessment (LCA) is difficult to understand from the point of view of instrumental decision making by economic agents. Ehrenfeld has argued, in a 1997 issue of this journal, that it is the world‐shaping potential of LCA that is more important than its use as a decision‐making tool. The present study attempts to explore the institutionalization of this “LCA world view” among ordinary market actors. This is important because environmental policy relies increasingly on market‐based initiatives. Cognitive and normative assumptions in authoritative LCA documents are examined as empirical data and compared with data from focus group interviews concerning products and the environment with “ordinary” manufacturers, retailers, and consumers in Finland. These assumptions are (1) the “cradle‐to‐grave” approach, (2) the view that all products have an environmental impact and can be improved, (3) the relativity of environmental merit, and (4) the way responsibility for environmental burdens is attributed. Relevant affinities, but also differences, are identified. It is argued that life‐cycle thinking is not primarily instrumental, but rather is gaining a degree of intrinsic value. The study attempts to establish a broader institutional context in which the popularity of LCA can be understood. From the point of view of this broader context, some future challenges for the development of LCA and life‐cycle thinking are suggested.
WHAT IF LUKE HAD NEVER MET THEOPHILUS?
Authors: Alexander Loveday C.A.
Published: July 2002

Asking the 'what if ?' questions of virtual history is a way of rubbing our noses in history's essential contingency—in the fact that things could have been different, that human choices (among other contingencies) actually matter. And of all history's contingencies, those of authorship seem—at least to those of us who are authors—the most precarious imaginable. With Luke we are dealing with an author who seems particularly sensitive to the delicate combinations of forces, both communal and individual, that hedge about the articulation of the word. Asking 'What if Luke had never met Theophilus?' is in the end an invitation to consider the possibility of the non-existence of Luke's Gospel and Acts. Can we imagine the New Testament without these two texts (which together make up 25% of its bulk)?
FROM REGIONAL TO PERSONAL SCHOOLS OF LAW? A REEVALUATION
Authors: Hallaq Wael
Published: July 2002

Western scholars have long regarded the legal history of the second/eighth century and the early part of the third/ninth as being dominated by the so-called geographical schools. Since scholars also hold that the later schools of law were personal in nature, it is widely assumed that a transformation took place from geographical schools to personal schools. In this article, I question these views, arguing (1) that geographical schools never existed; (2) that the later schools were not personal; and (3) that a transformation did in fact take place, albeit from individual juristic doctrines to doctrinal schools.
Scepticism and Ineffability in Plotinus
Authors: O'Meara Dominic
Published: July 2002

The first part of this paper traces back to Plotinus a strategy applied by Augustine and Descartes whereby sceptical arguments are used to set aside sensualist forms of dogmatic philosophy, clearing the way for a dogmatism independent of sense-perception which is 'self-authenticating' and thus immune to, and even proven by, sceptical doubt. It is argued that Plotinus already uses this strategy in the opening chapters of Enneads V 5 and V 3. The second part of the paper argues that Plotinus' account of how the ineffable One is said (we do not actually say the One, but merely express our own affections) is inspired by the structure of sceptic discourse (the sceptic does not say things as they are, but merely expresses personal affections). Finally, similarities and differences between sceptic discourse about things and Plotinian discourse about the ineffable are explored.
Proclus vs Plotinus on Matter (De mal. subs. 30-7 )
Authors: Opsomer Jan
Published: July 2002

In De malorum subsistentia chs 30-7, Proclus criticizes the view that evil is to be identified with matter. His main target is Plotinus' account in Enn. I,8 \[51]. Proclus denies that matter is the cause of evil in the soul, and that it is evil or a principle of evil. According to Proclus, matter is good, because it is produced by the One. Plotinus' doctrine of matter-evil is the result of a different conception of emanation, according to which matter does not revert to its principle. Proclus claims that to posit a principle of evil either amounts to a coarse dualism, or makes the Good ultimately responsible for evil. Plotinus does not seem to be able to escape the latter consequence, if he is to remain committed to the Neoplatonic conception of causation. Plotinus equated matter with privation and said it is a kind of non-being that is the contrary of substance, thus violating fundamental Aristotelian tenets. Proclus reinstates Aristotelian orthodoxy, as does Simplicius in his Commentary on the Categories. It is possible that Iamblichus was the source of both Proclus and Simplicius, and that he was the originator of the parhypostasis theory and the inventor of the anti-Plotinian arguments.
Water collection by the body in a viperid snake, Bothrops moojeni
Authors: Abe Augusto , Andrade Denis
Published: July 2002

We describe a previously unreported behavior for water collection in juveniles of a neotropical viperid snake, Bothrops moojeni. When sprayed over, this snake displays a stereotyped coiling, bringing its body loops in close contact with each other, so that water is retained between the loops and over the body surface. This water is continuously ingested during and after its collection. The functional significance of the water collecting behavior is suggested to be related with the acquisition of water from short rainfalls, and with the special climatic and geologic conditions of B. moojeni habitat. Rates of evaporative water loss did not differ between juvenile and adult snakes, but since juveniles have a greater surface-to-volume ratio, they were significantly more sensitive to desiccation than the adults.
A new species of Brachycephalus (Anura: Brachycephalidae) from Atlantic Rain Forest of southeastern Brazil
Authors: Pombal José
Published: July 2002

A new species of Brachycephalus is described from Serra da Bocaina, State of Rio de Janeiro, Brazil. The new species is characterized by having, in preservative, body uniformly pale cream, dermal ossification of the vertebrae composed of a bulge forming a row, and absence of ossified warts on the body.
Seasonal activity of snakes in the Atlantic forest in southeastern Brazil
Authors: Eterovic André , Marques Otavio , Endo Whaldener
Published: July 2002

Seasonal abundance of some snake species from the Atlantic forest in southeastern Brazil was inferred from collection data gathered throughout twelve years at the Instituto Butantan in São Paulo, Brazil. The number of collected individuals of Chironius spp., Liophis miliaris, Spilotes pullatus, Tropidodryas spp., Micrurus corallinus, and Bothrops jararaca was significantly higher during the rainy season, whereas the number of Sibynomorphus neuwiedi was higher during the dry season. Erythrolamprus aesculapii, Xenodon neuwiedii, Tomodon dorsatus and Bothrops jararacussu did not show significant differences in the number of individuals collected at each of these seasons. Seasonality in captures may result from seasonal activity patterns. Food availability, tolerance to climatic conditions, reproductive cycle, and phylogenetic constraints are considered the main factors responsible for the observed patterns. A multivariate approach is recommended for analysis of annual activity.
INFLUENCE OF INSECT ASSOCIATED CUES ON THE JUMPING BEHAVIOR OF ENTOMOPATHOGENIC NEMATODES (STEINERNEMA SPP.)
Authors: Campbell James , Kaya Harry
Published: July 2002

The infective stage juveniles of insect parasitic nematodes in the family Steinernema search for hosts using strategies ranging from ambush to cruise foraging. Infective juveniles attach to passing insects by standing on their tails and contacting an insect directly when standing or by jumping. We determined how species with differing degrees of ambush foraging specialization differ in their behavioral responses to different sources of information. Mechanical contact, air movement, and host associated volatile cues were important triggers of jumping behavior for some species of Steinernema. Three species that are ambush foragers (S. carpocapsae, S. scapterisci, and S. siamkayai) responded to small air movements by increased waving and jumping behavior, and jumps were directionally biased towards the source of the movement. For S. carpocapsae and S. scapterisci, host-associated volatile cues were strong triggers to jump, but host cues did not increase the proportion of S. siamkayai jumping. In contrast, two intermediate foraging species, S. ceratophorum and S. monticolum, did not demonstrate a detectable response to either the air movement or the host cues.
SPONGE-INHABITING BARNACLES OF THE AMERICAS: A NEW SPECIES OF ACASTA (CIRRIPEDIA, ARCHAEOBALANIDAE), FIRST RECORD FROM THE EASTERN PACIFIC, INCLUDING DISCUSSION OF THE EVOLUTION OF CIRRAL MORPHOLOGY
Authors: Winther Rasmus , Syoc Robert J. Van
Published: July 2002

Se describe Acasta newmani n. sp. del Golfo de California. Esta es la primera cita de Acasta en el Pacofico oriental. Se discuten las hip otesis sobre la correlacion entre morfologoa cirral y los metodos de alimentacion y especificidad de huespedes. Las similitudes, entre A. newmani y A. cyathus Darwin, 1854 indican que son un ejemplo del patron comun entre especies hermanas a ambos lados del istmo de Panama, en el Caribe y Pacofico oriental tropical. Se incluye una clave de las siete especies americanas de cirropedos que viven en esponjas, indicando la especie huesped y sus distribuciones. El rango de distribucion de Membranobalanus nebrias (Zullo & Beach, 1973) se extiende desde las islas Gal apagos hasta el Golfo de California. Acasta newmani n. sp. from the Gulf of California, Mexico is described. This is the first report of Acasta from the eastern Pacific. Hypotheses are discussed concerning the correlation of cirral morphology with feeding methods and host specificity. The similarities between A. newmani and Acasta cyathus Darwin, 1854 indicate that they are examples of the common pattern of trans-isthmian sibling taxa in the Caribbean and eastern tropical Pacific. A key to the seven sponge-inhabiting barnacle species of the Americas is presented with citations noting their host sponge species and known ranges in the Americas. The range of Membranobalanus nebrias (Zullo & Beach, 1973) is extended from the Galapagos Islands to the Gulf of California.
Enzyme phenotypes of Meloidogyne spp. populations
Authors: Carneiro Regina M.D.G. , Quénéhervé Patrick , Almeida Maria Ritta
Published: July 2002

Enzyme phenotypes, specifically esterases (EST), malate dehydrogenase (MDH), superoxide dismutase (SOD) and glutamate-oxaloacetate transaminase (GOT) were used to characterise different species of Meloidogyne, mostly from Brazil and from some American countries. Esterase activity was highly polymorphic and was the most useful in the identification of the different species. Using this enzyme it is possible to characterise and identify the four major species: M. javanica, M. incognita, M. arenaria and M. hapla from a large collection of 111 populations of Meloidogyne spp. Another seven less common species (M. coffeicola, M. paranensis, M. konaensis, M. exigua, M. graminicola, M. oryzae, M. mayaguensis), with only one or a few populations of each, were studied and exhibited species-specific EST phenotypes. The two enzymes (EST and MDH) differentiated M. graminicola and M. oryzae. It was possible to detect atypical (unidentified) phenotypes: three from Brazil, one from the USA and another from Chile. The minor bands of esterase profiles provided information to detect intraspecific variability among some populations of M. incognita and six populations of M. exigua. Profiles of MDH permitted separation of two isolates of M. javanica from Brazil. Phénotypes enzymatiques de populations de Meloidogyne - Les phénotypes enzymatiques de l'estérase (EST), la malate déshydrogènase (MDH), la superoxide dismutase (SOD) et la glutamate-oxaloacétate transaminase (GOT) ont été utilisés de manière systématique afin de caractériser plusieurs espèces de Meloidogyne provenant principalement du Brésil et de quelques pays des régions américaines. C'est l'activité estérasique qui a présenté le plus grand polymorphisme et s'est montrée la plus utile dans la caractérisation des espèces. A l'aide de cette enzyme il a été possible de caractériser et d'identifier les quatre espèces majeures de Meloidogyne: M. javanica, M. incognita, M. arenaria, et M. hapla au sein d'une collection de 111 populations de Meloidogyne spp. Sept autres espèces moins fréquentes (M. coffeicola, M. paranensis, M. konaensis, M. exigua, M. graminicola, M. oryzae, M. mayaguensis) comportant seulement quelques populations de chaque espèces ont été étudiées et ont également montré des phénotypes estérasiques spécifiques. Les deux enzymes (EST et MDH) ont permis la différenciation de M. graminicola et de M.oryzae. Il a été également possible de détecter des phénotypes atypiques non encore identifiés chez trois populations originaires du Brésil, une des USA et une du Chili. Par ailleurs, les bandes mineures des profils estérasiques ont apporté des informations sur la variabilité intra-spécifique chez quelques populations de M. incognita et six populations de M. exigua, tandis que l'observation des profils enzymatiques de la malate déshydrogènase (MDH) a permis la distinction de deux populations de M. javanica du Brésil.