bluuebunny/crossref_metadata_2025 huggingface dataset:
The profile naming service
Authors: Peterson Larry L.
Published: July 2002

Profile is adescriptivenaming service used to identify users and organizations. This paper presents a structural overview of Profile's three major components: a confederation ofattribute-basedname servers, a name space abstraction that unifies the name servers, and a user interface that integrates the name space with existing naming systems. Each name server is an independent authority that allows clients to describe users and organizations with a multiplicity of attributes; the name space abstraction is a client program that implements a discipline for searching a sequence of name servers; and the interface provides a tool with which users build customized commands. Experience with an implementation in the DARPA/NSF Internet demonstrates that Profile is a feasible and effective mechanism for naming users and organizations in a large internet.
Algorithm 666: Chabis: a mathematical software package for locating and evaluating roots of systems of nonlinear equations
Authors: Vrahatis Michael N.
Published: July 2002

CHABIS is a mathematical software package for the numerical solution of a system of n nonlinear equations in
n
variables. First, CHABIS locates at least one solution of the system within an
n
-dimensional polyhedron. Then, it applies a new generalized method of bisection to this
n
-polyhedron in order to obtain an approximate solution of the system according to a predetermined accuracy. In this paper we briefly describe the user interface to CHABIS and present several details of its implementation, as well as an example of its usage.
Real-time texture synthesis by patch-based sampling
Authors: Liang Lin , Liu Ce , Xu Ying-Qing , Guo Baining , Shum Heung-Yeung
Published: July 2002

We present an algorithm for synthesizing textures from an input sample. This patch-based sampling algorithm is fast and it makes high-quality texture synthesis a real-time process. For generating textures of the same size and comparable quality, patch-based sampling is orders of magnitude faster than existing algorithms. The patch-based sampling algorithm works well for a wide variety of textures ranging from regular to stochastic. By sampling patches according to a nonparametric estimation of the local conditional MRF density function, we avoid mismatching features across patch boundaries. We also experimented with documented cases for which pixel-based nonparametric sampling algorithms cease to be effective but our algorithm continues to work well.
Probabilistic object bases
Authors: Eiter Thomas , Lu James J. , Lukasiewicz Thomas , Subrahmanian V. S.
Published: July 2002

Although there are many applications where an object-oriented data model is a good way of representing and querying data, current object database systems are unable to handle objects whose attributes are uncertain. In this article, we extend previous work by Kornatzky and Shimony to develop an algebra to handle object bases with uncertainty. We propose concepts of consistency for such object bases, together with an NP-completeness result, and classes of probabilistic object bases for which consistency is polynomially checkable. In addition, as certain operations involve conjunctions and disjunctions of events, and as the probability of conjunctive and disjunctive events depends both on the probabilities of the primitive events involved as well as on what is known (if anything) about the relationship between the events, we show how all our algebraic operations may be performed under arbitrary probabilistic conjunction and disjunction strategies. We also develop a host of equivalence results in our algebra, which may be used as rewrite rules for query optimization. Last but not least, we have developed a prototype probabilistic object base server on top of ObjectStore. We describe experiments to assess the efficiency of different possible rewrite rules.
Algorithm 813
Authors: Birgin Ernesto G. , Martínez José Mario , Raydan Marcos
Published: July 2002

Fortran 77 software implementing the SPG method is introduced. SPG is a nonmonotone projected gradient algorithm for solving large-scale convex-constrained optimization problems. It combines the classical projected gradient method with the spectral gradient choice of steplength and a nonmonotone line-search strategy. The user provides objective function and gradient values, and projections onto the feasible set. Some recent numerical tests are reported on very large location problems, indicating that SPG is substantially more efficient than existing general-purpose software on problems for which projections can be computed efficiently.
Datalog LITE
Authors: Gottlob Georg , Grädel Erich , Veith Helmut
Published: July 2002

We present Datalog LITE, a new deductive query language with a linear-time model-checking algorithm, that is, linear time data complexity and program complexity. Datalog LITE is a variant of Datalog that uses stratified negation, restricted variable occurrences and a limited form of universal quantification in rule bodies.Despite linear-time evaluation, Datalog LITE is highly expressive: It encompasses popular modal and temporal logics such as CTL or the alternation-free μ-calculus. In fact, these formalisms have natural presentations as fragments of Datalog LITE. Further, Datalog LITE is equivalent to the alternation-free portion of guarded fixed-point logic. Consequently, linear-time model checking algorithms for all mentioned logics are obtained in a unified way.The results are complemented by inexpressibility proofs to the effect that linear-time fragments of
stratified
Datalog have too limited expressive power.
A discipline for constructing multiphase communication protocols
Authors: Chow Ching-Hua , Gouda Mohamed G. , Lam Simon S.
Published: July 2002

Many communication protocols can be observed to go through different phases performing a distinct function in each phase. A multiphase model for such protocols is presented. A phase is formally defined to be a network of communicating finite-state machines with certain desirable correctness properties; these include proper termination and freedom from deadlocks and unspecified receptions. A multifunction protocol is constructed by first constructing separate phases to perform its different functions. It is shown how to connect these phases together to realize the multifunction protocol so that the resulting network of communicating finite state machines is also a phase (i.e., it possesses the desirable properties defined for phases). The modularity inherent in multiphase protocols facilitates not only their construction but also their understanding and modification. An abundance of protocols have been found in the literature that can be constructed as multiphase protocols. Three examples are presented here: two versions of IBM's BSC protocol for data link control and a token ring network protocol.
The performance of multiversion concurrency control algorithms
Authors: Carey Michael J. , Muhanna Waleed A.
Published: July 2002

A number of multiversion concurrency control algorithms have been proposed in the past few years. These algorithms use previous versions of data items in order to improve the level of achievable concurrency. This paper describes a simulation study of the performance of several multiversion concurrency control algorithms, investigating the extent to which they provide increases in the level of concurrency and also the CPU, I/O, and storage costs resulting from the use of multiple versions. The multiversion algorithms are compared with regard to performance with their single-version counterparts and also with each other. It is shown that each multiversion algorithm offers significant performance improvements despite the additional disk accesses involved in accessing old versions of data; the nature of the improvement depends on the algorithm in question. It is also shown that the storage overhead for maintaining old versions that may be required by ongoing transactions is not all that large under most circumstances. Finally, it is demonstrated that it is important for version maintenance to be implemented efficiently, as otherwise the cost of maintaining old versions could outweigh their concurrency benefits.
Optimal bounds for decision problems on the CRCW PRAM
Authors: Beame Paul , Hastad Johan
Published: July 2002

Optimal Ω(log
n
/log log
n
) lower bounds on the time for CRCW PRAMS with polynomially bounded numbers of processors or memory cells to compute parity and a number of related problems are proven. A strict time hierarchy of explicit Boolean functions of
n
bits on such machines that holds up to Ο(log
n
/log log
n
) time is also exhibited. That is, for every time bound
T
within this range a function is exhibited that can be easily computed using polynomial resources in time
T
but requires more than polynomial resources to be computed in time
T
- 1. Finally, it is shown that almost all Boolean functions of
n
bits require log
n
- log log
n
+ Ω(1) time when the number of processors is at most polynomial in
n
. The bounds do not place restrictions on the uniformity of the algorithms nor on the instruction sets of the machines.
ELFS: English language from SQL
Authors: Luk W. S. , Kloster Steve
Published: July 2002

In this paper we describe a system which, given a query in SQL-like relational database language, will display its meaning in clear, unambiguous natural language. The syntax-driven translation mechanism is independent of the application domain. It has direct applications in designing computer-based SQL tutorial systems and program debugging systems. The research results obtained in the paper will also be useful in query optimization and design of a more user-friendly language front-end
for casual users.
The 3DIS: an extensible object-oriented information management environment
Authors: Afsarmanesh Hamideh , McLeod Dennis
Published: July 2002

The 3-Dimensional Information Space (3DIS) is an extensible object-oriented framework for information management. It is specifically oriented toward supporting the database requirements for data-intensive information system applications in which (1) information objects of various levels of abstraction and modalities must be accommodated, (2) descriptive and structural information (metadata) is rich and dynamic, and (3) users who are not database experts must be able to design, manipulate, and evolve databases. In response to these needs, the 3DIS provides an approach in which data and the descriptive information about data are handled uniformly in an extensible framework. The 3DIS provides a simple, geometric, and formal representation of data which forms a basis for understanding, defining, and manipulating databases. Several prototype implementations based upon the 3DIS have been designed and implemented and are in experimental use.
Parse tree annotations
Authors: Purtilo James J. , Callahan John R.
Published: July 2002

A technique for associating rewrite rules with productions so that many high-level transformations of a source file can be generated easily is described. While eclipsed in power by other editing and compiler generation systems supporting management of both synthesized and inherited attributes, this approach is especially simple to employ and is sufficient in power to deal with a wide class of problems arising from practical applications.
Extending the radiosity method to include specularly reflecting and translucent materials
Authors: Rushmeier Holly E. , Torrance Kenneth E.
Published: July 2002

An extension of the radiosity method is presented that rigorously accounts for the presence of a small number of specularly reflecting surfaces in an otherwise diffuse scene, and for the presence of a small number of specular or ideal diffuse transmitters. The relationship between the extended method and earlier radiosity and ray-tracing methods is outlined. It is shown that all three methods are based on the same general equation of radiative transfer. A simple superposition of the earlier radiosity and ray-tracing methods in order to account for specular behavior is shown to be physically inconsistent, as the methods are based on different assumptions. Specular behavior is correctly included in the present method. The extended radiosity method and example images are presented.
The implementation of an algorithm to find the convex hull of a set of three-dimensional points
Authors: Day A. M.
Published: July 2002

A detailed description of the implementation of a three-dimensional convex hull algorithm is given. The problems experienced in the production and testing of a correct and robust implementation of a geometric algorithm are discussed. Attention is paid to those issues that are often brushed over in the theoretical descriptions but cause errors in a real computation. These include degeneracies such as coplanar points, floating-point errors, and other special, but not necessarily degenerate, cases.
COMING TO TERMS WITH HUMAN VARIATION
Authors: Weiss Kenneth M.
Published: July 2002

▪ Abstract  Genetics has become the major tool of the life sciences. This is driven partly by technology, and partly by the belief that genes are the ultimate units of biomedical or evolutionary information. The search for variation associated with disease has motivated the Human Genome Project to construct a detailed road map of the entire set of human genetic material, and some additional form of globally representative human genome diversity resource has been proposed for the anthropological purposes of reconstructing human population history. Any such resource raises complex societal and ethical issues as well as scientific ones. However, the amount and complexity of genetic variation has frustrated hopes for simple genetic answers to important biomedical or anthropological questions, and a consequent converging of these differing interests suggests that developing a genetic variation resource will be important in many disciplines.
Cellular Microtransport Processes: Intercellular, Intracellular, and Aggregate Behavior
Authors: Nitsche Johannes M.
Published: July 2002

▪ Abstract  Ionic and molecular transfer among cells occurs by a variety of transport processes operative at different length scales. Cell membrane permeability and electrical conductance derive from channel proteins producing pores at the molecular (ultrastructural) scale. Intracellular mobility involves the dynamics of motion through the complex ultrastructure of the cytoplasm. These phenomena unite in the larger-scale (microscopic) process of gross intercellular transfer. When such movement occurs among sufficiently many cells, it in turn begins to reflect their average collective (macroscopic) behavior as bulk tissue. This article surveys selected aspects of intercellular and intracellular transport, with emphasis on detailed mechanistic theory, experimental probes of cellular permeability, and systematic transcendence from small to large length scales.
THE DEGLACIATION OF THE NORTHERN HEMISPHERE: A Global Perspective
Authors: Alley Richard B. , Clark Peter U.
Published: July 2002

▪ Abstract  Orbitally induced increase in northern summer insolation after growth of a large ice sheet triggered deglaciation and associated global warming. Ice-albedo, sea-level, and greenhouse-gas feedbacks, together with tropical warming from weakening winds in response to polar amplification of warming, caused regional-to-global (near-) synchronization of deglaciation. Effects were larger at orbital rather than millennial frequencies because ice sheets and carbon dioxide vary slowly. Ice-sheet–linked changes in freshwater delivery to the North Atlantic, and possibly free oscillations in the climate system, forced millennial climate oscillations associated with changes in North Atlantic deep water (NADW) flow. The North Atlantic typically operates in one of three modes: modern, glacial, and Heinrich. Deglaciation occurred from a glacial-mode ocean that, in comparison to modern, had shallower depth of penetration of NADW formed further south, causing strong northern cooling and the widespread cold, dry, and windy conditions associated with the glacial maximum and the cold phases of the millennial Dansgaard-Oeschger oscillations. The glacial mode was punctuated by meltwater-forced Heinrich conditions that caused only small additional cooling at high northern latitudes, but greatly reduced the formation of NADW and triggered an oceanic “seesaw” that warmed some high-latitude southern regions centered in the South Atlantic.
PREDACEOUS COCCINELLIDAE IN BIOLOGICAL CONTROL
Authors: Obrycki John J. , Kring Timothy J.
Published: July 2002

▪ Abstract  Coccinellids have been widely used in biological control for over a century, and the methods for using these predators have remained virtually unchanged. The causes for the relatively low rates of establishment of coccinellids in importation biological control have not been examined for most species. Augmentative releases of several coccinellid species are well documented and effective; however, ineffective species continue to be used because of ease of collection. For most agricultural systems, conservation techniques for coccinellids are lacking, even though they are abundant in these habitats. Evaluation techniques are available, but quantitative assessments of the efficacy of coccinellids have not been done for most species in most agricultural crops. Greater emphasis is needed on evaluation, predator specificity, understanding colonization of new environments, and assessment of community-level interactions to maximize the use of coccinellids in biological control.
REGULATION OF T CELL FATE BY NOTCH
Authors: Robey Ellen
Published: July 2002

▪ Abstract  The transmembrane receptor Notch participates in diverse cell fate decisions throughout embryonic development. Notch receptors and their ligands are expressed in the mammalian thymus, raising the possibility that Notch could regulate T cell fate decisions. Expression of a constitutively activated form of Notch in developing thymocytes causes thymocytes normally destined for the CD4 lineage to adopt the CD8 lineage instead. This suggests that Notch activity normally acts to direct CD4+CD8+ precursors to the CD8 lineage. The choice between CD4 and CD8 T cell fates is also controlled by MHC recognition during positive selection, implying that recognition of class I or II MHC might regulate Notch signaling. Possible models for the regulation of Notch by MHC recognition during CD4 versus CD8 lineage determination are discussed.
COBALAMIN (COENZYME B12): Synthesis and Biological Significance
Authors: Roth JR , Lawrence JG , Bobik TA
Published: July 2002

This review examines deoxyadenosylcobalamin (Ado-B12) biosynthesis, transport, use, and uneven distribution among living forms. We describe how genetic analysis of enteric bacteria has contributed to these issues. Two pathways for corrin ring formation have been found–an aerobic pathway (in P. denitrificans) and an anaerobic pathway (in P. shermanii and S. typhimurium)–that differ in the point of cobalt insertion. Analysis of B12 transport in E. coli reveals two systems: one (with two proteins) for the outer membrane, and one (with three proteins) for the inner membrane. To account for the uneven distribution of B12 in living forms, we suggest that the B12 synthetic pathway may have evolved to allow anaerobic fermentation of small molecules in the absence of an external electron acceptor. Later, evolution of the pathway produced siroheme, (allowing use of inorganic electron acceptors), chlorophyll (O2 production), and heme (aerobic respiration). As oxygen became a larger part of the atmosphere, many organisms lost fermentative functions and retained dependence on newer, B12 functions that did not involve fermentation. Paradoxically, Salmonella spp. synthesize B12 only anaerobically but can use B12 (for degradation of ethanolamine and propanediol) only with oxygen. Genetic analysis of the operons for these degradative functions indicate that anaerobic degradation is important. Recent results suggest that B12 can be synthesized and used during anaerobic respiration using tetrathionate (but not nitrate or fumarate) as an electron acceptor. The branch of enteric taxa from which Salmonella spp. and E. coli evolved appears to have lost the ability to synthesize B12 and the ability to use it in propanediol and glycerol degradation. Salmonella spp., but not E. coli, have acquired by horizontal transfer the ability to synthesize B12 and degrade propanediol. The acquired ability to degrade propanediol provides the selective force that maintains B12 synthesis in this group.
THE MAMMALIAN CARBOXYLESTERASES: From Molecules to Functions
Authors: Satoh Tetsuo , Hosokawa Masakiyo
Published: July 2002

▪ Abstract  Multiple carboxylesterases (EC 3.1.1.1) play an important role in the hydrolytic biotransformation of a vast number of structurally diverse drugs. These enzymes are major determinants of the pharmacokinetic behavior of most therapeutic agents containing ester or amide bonds. Carboxylesterase activity can be influenced by interactions of a variety of compounds either directly or at the level of enzyme regulation. Since a significant number of drugs are metabolized by carboxylesterase, altering the activity of this enzyme class has important clinical implications. Drug elimination decreases and the incidence of drug-drug interactions increases when two or more drugs compete for hydrolysis by the same carboxylesterase isozyme. Exposure to environmental pollutants or to lipophilic drugs can result in induction of carboxylesterase activity. Therefore, the use of drugs known to increase the microsomal expression of a particular carboxylesterase, and thus to increase associated drug hydrolysis capacity in humans, requires caution.

Mammalian carboxylesterases represent a multigene family, the products of which are localized in the endoplasmic reticulum of many tissues. A comparison of the nucleotide and amino acid sequence of the mammalian carboxylesterases shows that all forms expressed in the rat can be assigned to one of three gene subfamilies with structural identities of more than 70% within each subfamily. Considerable confusion exists in the scientific community in regards to a systematic nomenclature and classification of mammalian carboxylesterase. Until recently, adequate sequence information has not been available such that valid links among the mammalian carboxylesterase gene family or evolutionary relationships could be established. However, sufficient basic data are now available to support such a novel classification system.
NEW INSIGHTS INTO DOPAMINERGIC RECEPTOR FUNCTION USING ANTISENSE AND GENETICALLY ALTERED ANIMALS
Authors: Sibley David R.
Published: July 2002

▪ Abstract  Dopaminergic receptors are widespread throughout the central and peripheral nervous systems, where they regulate a variety of physiological, behavioral, and endocrine functions. These receptors are also clinically important drug targets for the treatment of a number of disorders, such as Parkinson's disease, schizophrenia, and hyperprolactinemia. To date, five different dopamine receptor subtypes have been cloned and characterized. Many of these subtypes are pharmacologically similar, making it difficult to selectively stimulate or block a specific receptor subtype in vivo. Thus, the assignment of various physiological or behavioral functions to specific dopamine receptor subtypes using pharmacological tools is difficult. In view of this, a number of investigators have—in order to elucidate functional roles—begun to use highly selective genetic approaches to alter the expression of individual dopamine receptor subtypes in vivo. This review discusses recent studies involving the use of genetic approaches for the study of dopaminergic receptor function.
FAST EVENTS IN PROTEIN FOLDING: The Time Evolution of Primary Processes
Authors: Callender Robert H. , Dyer R. Brian , Gilmanshin Rudolf , Woodruff William H.
Published: July 2002

▪ Abstract  Most experimental studies on the dynamics of protein folding have been confined to timescales of 1 ms and longer. Yet it is obvious that many phenomena that are obligatory elements of the folding process occur on much faster timescales. For example, it is also now clear that the formation of secondary and tertiary structures can occur on nanosecond and microsecond times, respectively. Although fast events are essential to, and sometimes dominate, the overall folding process, with a few exceptions their experimental study has become possible only recently with the development of appropriate techniques. This review discusses new approaches that are capable of initiating and monitoring the fast events in protein folding with temporal resolution down to picoseconds. The first important results from those techniques, which have been obtained for the folding of some globular proteins and polypeptide models, are also discussed.
Role of CFTR in the Colon
Authors: Greger R.
Published: July 2002

▪ Abstract  In contrast to the airways, the defects in colonic function in cystic fibrosis (CF) patients are closely related to the defect in CFTR. The gastrointestinal phenotype of CF transgenic mice closely resembles the phenotype in CF patients, which clearly indicates the crucial role of CFTR in colonic Cl− secretion and the absence of an effective compensation.

In the colon, stimulation of CFTR Cl− channels involves cAMP- or cGMPdependent phosphorylation. Exocytosis is not involved. Activation of CFTR leads to coactivation of basolateral KVLQT1-type K+ channels and inhibition of luminal Na+ channels (ENaC). In contrast to cultured cells, Ca2+ does not activate luminal Cl− channels in intact enterocytes. It activates basolateral SK4-type K+ channels and luminal K+ channels, which provide additional driving force for Cl− exit. The magnitude of Cl− secretion, however, completely depends on the presence of at least a residual CFTR function in the luminal membrane.

These findings have been clearly demonstrated by Ussing chamber experiments in colon epithelium biopsies of CF and normal individuals: Colonic Cl− secretion in CF patients is variable and reflects the genotype; a complete defect of CFTR is paralleled by the absence of Cl− secretion and unmasks Ca2+-regulated K+ channels in the luminal membrane; overabsorption of Na+ in CF reflects the absence of ENaC inhibition by CFTR; and the functional status of CF colon can be mimicked by the complete suppression of cAMP stimulation in enterocytes of healthy individuals.
Transnational Politics: Contention and Institutions in International Politics
Authors: Tarrow Sidney
Published: July 2002

Recent scholars have broadened the study of transnational relations, once limited to political economy, to include contentious international politics. This is a refreshing trend, but most of them leap directly from globalization or some other such process to transnational social movements and thence to a global civil society. In addition, they have so far failed to distinguish among movements, nongovernmental organizations (NGOs), and transnational networks and do not adequately specify their relations with states and international institutions. In particular, few mechanisms are proposed to link domestic actors to transnational ones and to states and international institutions. This paper argues that mass-based transnational social movements are hard to construct, are difficult to maintain, and have very different relations to states and international institutions than more routinized international NGOs or activist networks. These latter forms may be encouraged both by states and international institutions and by the growth of a cosmopolitan class of transnational activists. Rather than being the antipodes of transnational contention, international institutions offer resources, opportunities, and incentives for the formation of actors in transnational politics. If transnational social movements form, it will be through a second-stage process of domestication of international conflict.
Gender in the Welfare State
Authors: Orloff Ann
Published: July 2002

Gender relations—embodied in the sexual division of labor, compulsory heterosexuality, gendered forms of citizenship and political participation, ideologies of masculinity and femininity, and the like—profoundly shape the character of welfare states. Likewise, the institutions of social provision—the set of social assistance and social insurance programs and universal citizenship entitlements to which we refer as “the welfare state” —affect gender relations. Until recently, two broad approaches to gender relations and welfare states predominated: one which saw states contributing to the social reproduction of gender hierarchies, and a second which saw states having an ameliorative impact on gender inequality. More recently, two new strands of research have emerged emphasizing the variation in the effects of social policies on gender.
Poverty and Inequality Among Children
Authors: Lichter Daniel T.
Published: July 2002

The deteriorating economic well-being of children portends less well-adjusted adults and a diminished economic future for America. A disproportionate share of today's poor children will become tomorrow's poor adults. This chapter discusses the concept, definition, and measurement of children's economic well-being and poverty. Children's current economic well-being is evaluated in comparative perspective—international, historical, and demographic. The chapter also evaluates the etiology of changes in children's absolute and relative economic well-being, focusing especially on the role of the changing family, parental employment, and levels of social provision for poor families. These “causes” are then evaluated in the context of recent public policy debates, including the devolution of federal welfare programs to the states.
Reactions Toward the New Minorities of Western Europe
Authors: Pettigrew Thomas F.
Published: July 2002

Millions of ex-colonials, “guest workers,” refugees, and other immigrants have settled in western Europe during recent decades. Extensive research on this phenomenon broadens sociology's understanding of intergroup relations in industrial societies. Unlike African Americans, these new Europeans are often viewed as not “belonging,” and gaining citizenship can be difficult. The chapter discusses four major reactions to the new minorities: prejudice, discrimination, political opposition, and violence. Both blatant and subtle forms of prejudice predict anti-immigrant attitudes. And between 1988 and 1991, a hardening took place in these attitudes. Similarly, direct and indirect discrimination against the new minorities is pervasive. Moreover, anti-discrimination efforts have been largely ineffective. Far-right, anti-immigration political parties have formed to exploit this situation. These openly racist parties have succeeded in shifting the political spectrum on the issue to the right. In addition, violence against third-world immigrants has increased in recent years, especially in nations such as Britain and Germany where far-right parties are weakest. The chapter concludes that these phenomena are remarkably consistent across western Europe. Furthermore, the European research on these topics supports and extends North American research in intergroup relations.
The Dichromaccord: Reinventing the Elusive Color Organ
Authors: Conrad Daniel
Published: July 2002

The author describes principles for a kinetic chro matic art form and illustrates examples of the medium as realized with the Dichromaccord, a color organ he created. The chromatic approach, extrapolated from the color studies of Josef Albers, uses the interaction between projected color and the afterimage of preceding colors as the source of motivating tension in color sequences and cadences.
Covert Reorienting and Inhibition of Return: An Event-Related fMRI Study
Authors: Lepsien Jöran , Pollmann Stefan
Published: July 2002

Using event-related fMRI, we analyzed the functional neuroanatomy of covert reorienting and inhibition of return (IOR). Covert reorienting to a target appearing within 250 msec after an invalid contralateral location cue elicited increased activation in the left fronto-polar cortex (LFPC), right anterior and left posterior middle frontal gyrus, and right cerebellum, areas that have previously been associated with attentional processes, specifically attentional change. In contrast, IOR, which leads to prolonged response times to targets that appear at the cued location at a stimulus-onset-asynchrony (SOA)>250 msec, was accompanied by increased activation in brain areas involved in oculomotor programming, such as the right medial frontal gyrus (supplementary eye field; SEF) and the right inferior precentral sulcus (frontal eye field; FEF), supporting the oculomotor bias theory of IOR. Pre-SEF and pre-FEF areas were involved both in covert reorienting and IOR. The supramarginal gyri were bilaterally involved in IOR, with the right supramarginal gyrus additionally involved in covert reorienting.
Evolution of Cooperative Problem Solving in an Artificial Economy
Authors: Baum Eric B. , Durdanovic Igor
Published: July 2002

We address the problem of how to reinforce learning in ultracomplex environments, with huge state-spaces, where one must learn to exploit a compact structure of the problem domain. The approach we propose is to simulate the evolution of an artificial economy of computer programs. The economy is constructed based on two simple principles so as to assign credit to the individual programs for collaborating on problem solutions. We find empirically that starting from programs that are random computer code, we can develop systems that solve hard problems. In particular, our economy learned to solve almost all random Blocks World problems with goal stacks that are 200 blocks high. Competing methods solve such problems only up to goal stacks of at most 8 blocks. Our economy has also learned to unscramble about half a randomly scrambled Rubik's cube and to solve several commercially sold puzzles.
Increased Synchrony with Increase of a Low-Threshold Calcium Conductance in a Model Thalamic Network: A Phase-Shift Mechanism
Authors: Thomas Elizabeth , Grisar Thierry
Published: July 2002

A computer model of a thalamic network was used in order to examine the effects of an isolated augmentation in a low-threshold calcium current. Such an isolated augmentation has been observed in the reticular thalamic (RE) nucleus of the genetic absence epilepsy rat from the Strasbourg (GAERS) model of absence epilepsy. An augmentation of the low-threshold calcium conductance in the RE neurons (gTs) of the model thalamic network was found to lead to an increase in the synchronized firing of the network. This supports the hypothesis that the isolated increase in gTs may be responsible for epileptic activity in the GAERS rat. The increase of gTs in the RE neurons led to a slight increase in the period of the isolated RE neuron firing. In contrast, the low-threshold spike of the RE neuron remained relatively unchanged by the increase of gTs. This suggests that the enhanced synchrony in the network was primarily due to a phase shift in the firing of the RE neurons with respect to the thalamocortical neurons. The ability of this phase-shift mechanism to lead to changes in synchrony was further examined using the model thalamic network. A similar increase in the period of RE neuron oscillations was obtained through an increase in the conductance of the calcium-mediated potassium channel. This change was once again found to increase synchronous firing in the network.
The VC Dimension for Mixtures of Binary Classifiers
Authors: Jiang Wenxin
Published: July 2002

The mixtures-of-experts (ME) methodology provides a tool of classification when experts of logistic regression models or Bernoulli models are mixed according to a set of local weights. We show that the Vapnik-Chervonenkis dimension of the ME architecture is bounded below by the number of experts m and above by O (m4s2), where s is the dimension of the input. For mixtures of Bernoulli experts with a scalar input, we show that the lower bound m is attained, in which case we obtain the exact result that the VC dimension is equal to the number of experts.
N-tuple Network, CART, and Bagging
Authors: Kołcz Aleksander
Published: July 2002

Similarities between bootstrap aggregation (bagging) and N-tuple sampling are explored to propose a retina-free data-driven version of the N-tuple network, whose close analogies to aggregated regression trees, such as classification and regression trees (CART), lead to further architectural enhancements. Performance of the proposed algorithms is compared with the traditional versions of the N-tuple and CART networks on a number of regression problems. The architecture significantly outperforms conventional N-tuple networks while leading to more compact solutions and avoiding certain implementational pitfalls of the latter.
Evaluating Auditory Performance Limits: II. One-Parameter Discrimination with Random-Level Variation
Authors: Heinz Michael G. , Colburn H. Steven , Carney Laurel H.
Published: July 2002

Previous studies have combined analytical models of stochastic neural responses with signal detection theory (SDT) to predict psychophysical performance limits; however, these studies have typically been limited to simple models and simple psychophysical tasks. A companion article in this issue (“Evaluating Auditory Performance Limits: I”) describes an extension of the SDT approach to allow the use of computational models that provide more accurate descriptions of neural responses. This article describes an extension to more complex psychophysical tasks. A general method is presented for evaluating psychophysical performance limits for discrimination tasks in which one stimulus parameter is randomly varied. Psychophysical experiments often randomly vary a single parameter in order to restrict the cues that are available to the subject. The method is demonstrated for the auditory task of random-level frequency discrimination using a computational auditory nerve (AN) model. Performance limits based on AN discharge times (all-information) are compared to performance limits based only on discharge counts (rate place). Both decision models are successful in predicting that random-level variation has no effect on performance in quiet, which is the typical result in psychophysical tasks with random-level variation. The distribution of information across the AN population provides insight into how different types of AN information can be used to avoid the influence of random-level variation. The rate-place model relies on comparisons between fibers above and below the tone frequency (i.e., the population response), while the all-information model does not require such across-fiber comparisons. Frequency discrimination with random-level variation in the presence of high-frequency noise is also simulated. No effect is predicted for all-information, consistent with the small effect in human performance; however, a large effect is predicted for rate-place in noise with random-level variation.
Constrained Optimization for Neural Map Formation: A Unifying Framework for Weight Growth and Normalization
Authors: Wiskott Laurenz , Sejnowski Terrence
Published: July 2002

Computational models of neural map formation can be considered on at least three different levels of abstraction: detailed models including neural activity dynamics, weight dynamics that abstract from the neural activity dynamics by an adiabatic approximation, and constrained optimization from which equations governing weight dynamics can be derived. Constrained optimization uses an objective function, from which a weight growth rule can be derived as a gradient flow, and some constraints, from which normalization rules are derived. In this article, we present an example of how an optimization problem can be derived from detailed nonlinear neural dynamics. A systematic investigation reveals how different weight dynamics introduced previously can be derived from two types of objective function terms and two types of constraints. This includes dynamic link matching as a special case of neural map formation. We focus in particular on the role of coordinate transformations to derive different weight dynamics from the same optimization problem. Several examples illustrate how the constrained optimization framework can help in understanding, generating, and comparing different models of neural map formation. The techniques used in this analysis may also be useful in investigating other types of neural dynamics.
Relating the Slope of the Activation Function and the Learning Rate Within a Recurrent Neural Network
Authors: Mandic Danilo P. , Chambers Jonathon A.
Published: July 2002

A relationship between the learning rate η in the learning algorithm, and the slope β in the nonlinear activation function, for a class of recurrent neural networks (RNNs) trained by the real-time recurrent learning algorithm is provided. It is shown that an arbitrary RNN can be obtained via the referent RNN, with some deterministic rules imposed on its weights and the learning rate. Such relationships reduce the number of degrees of freedom when solving the nonlinear optimization task of finding the optimal RNN parameters.
Probabilistic Synaptic Transmission in the Associative Net
Authors: Graham Bruce , Willshaw David
Published: July 2002

The associative net model of heteroassociative memory with binary-valued synapses has been extended to include recent experimental data indicating that in the hippocampus, one form of synaptic modification is a change in the probability of synaptic transmission. Pattern pairs are stored in the net by a version of the Hebbian learning rule that changes the probability of transmission at synapses where the presynaptic and post-synaptic units are simultaneously active from a low, base value to a high, modified value. Numerical calculations of the expected recall response of this stochastic associative net have been used to assess the performance for different values of the base and modified probabilities. If there is a cost incurred with generating the difference between these probabilities, then a difference of about 0.4 is optimal. This corresponds to the magnitude of change seen experimentally. Performance can be greatly enhanced by using multiple cue presentations during recall.
An Approach to Compositional Trends in Latin America
Authors: Aharonián Coriún
Published: July 2002

Any attempt to theorize about Latin American composition will necessarily involve a prejudgment of which composers to consider. In addition the context of a colonial system of cultural transmission should not be ignored. This context makes it important to evaluate a composer's significance in terms of his or her distinctiveness in the light of metropolitan composers and compositions. A number of characteristic trends can be seen in the works of composers who meet these criteria, including a distinctive sense of time; use of nondiscursive, reiterative processes; austerity; violence; the breach of technological and cultural boundaries; and an interest in cultural identity.
A Web-Based Publishing-Management System
Authors: Kjolaas Kari Anne H. , Wiegand Thomas E. von , Sachtler W. L.
Published: July 2002

The management of a large number of manuscripts is integral to the publishing of a scientific journal. The process of submitting articles should be as simple as possible, both for the sake of the authors and for the reduction of the overhead associated with mailing and handling. For these reasons, the entire pre-press process at Presence is now based on standard Internet protocols. Although a hardcopy document is still required by the publisher, the pre-press process—from original submission through the stages of review—to final acceptance for publication—can now be done electronically. All functions involving electronic manuscript submission and management, as well as correspondence with reviewers, has been bundled in a modular package amenable to modifications. This publishing system was developed in-house at a fraction of the cost of acquiring a commercially available system. It was designed in close cooperation with the editorial staff to ensure optimal functionality.
CONFLICT: THE PARABLE OF THE GOOD SAMARITAN JESUS AND THE REDUCTION OF INTERGROUP IN THE LIGHT OF SOCIAL IDENTITY THEORY
Authors: Esler Philip
Published: July 2002

This article explores the Parable of the Good Samaritan in its immediate context (Luke 10:25-37), a central New Testament passage, both to assess its meaning for Luke's audience and also to suggest its pertinence to contemporary interest in reducing intergroup tension and conflict, especially between ethnic groups. The article first discusses social identity theory, which was developed by Henri Tajfel et al. and which deals with how groups provide their members a valued sense of identity through (often violent) differentiation from other groups. After next describing the violent history of the intergroup relationship between Judeans and Samaritans, as reflected in New Testament passages such as Luke 9:51-55, the article then presents an analysis of Luke 10:15-37 aimed at determining how Jesus uses the parable to subvert the connection between Judean group identity and the Mosaic law and to propose a new approach to moral behaviour. These exegetical results are then analysed in the light of three approaches to reducing intergroup conflict (crossed categorization, recategorization and decategorization) and the latter is found to be most analogous to the approach taken by the Lucan Jesus. The conclusion suggests the relevance of the parable to contemporary efforts to eliminate intergroup conflict.
NAKHUDAS AND NAUVITTAKAS: SHIP-OWNING MERCHANTS IN THE WEST COAST OF INDIA (C. AD 1000-1500)
Authors: Chakravarti Ranabir
Published: July 2002

Among the diverse types of merchants active in India during the first half of the second millennium, the ship-owning merchants occupy a prominent position in the coastal areas of western India (especially at ports). These merchants are given distinct epithets nakhuda and nauvittaka, the two terms being occasionally used as interchangeable ones and also in their abbreviated forms in official documents. Known from the medieval Jewish letters of 'India Traders', copper plates, a bilingual inscription, Arabic accounts and epitaphs and Jaina carita (biographical) texts, nakudas and nauvittkas of different religious leanings (Jewish, Muslim and Hindu) illustrate remarkable co-operation and social amity and religious toleration, which underline their importance in the Indian Ocean maritime network prior to AD 1500. Possessing considerable wealth, these ship-owning merchants can be considered as elites in the ports of coastal western India and were also known for their patronage to religious and cultural activities. The paper is presented as a tribute to the memory of Professor Ashin Das Gupta who immensely enlightened us on the ship-owners of coastal western India between 1500-1800.
Transmissive Frequency, Ritual, and Exegesis
Authors: Whitehouse Harvey
Published: July 2002

Certain aspects of the relations between ritual action and ritual meaning are determined by socially regulated cycles of transmissive frequency, via the highly structured operations of human memory. Evidence is presented in this article that: (i) the relative scarcity of spontaneous exegetical reflection and the relatively wide dissemination of standard official exegesis in routinized traditions, may be explained by the dynamics of implicit procedural memory and the opportunities afforded by repetition for the spread of stable theological/exegetical representations encoded in semantic memory; (ii) the relative scarcity or restricted distribution of official exegesis and the relatively high degree of elaboration of spontaneous exegetical reflection in rare and climactic rituals, may be explained by the dynamics of episodic memory. These arguments are shown to have potentially significant implications for epidemiological perspectives on cognition and religion.