bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating the cost of updates in a relational database
Authors: Schkolnick M. , Tiberio P.
Published: July 2002

In this paper, cost formulas are derived for the updates of data and indexes in a relational database. The costs depend on the data scan type and the predicates involved in the update statements. We show that update costs have a considerable influence, both in the context of the physical database design problem and in access path selection in query optimization for relational DBMSs.
Algorithm 658
Authors: Leis Jorge R. , Kramer Mark A.
Published: July 2002

ODESSA is a package of FORTRAN routines for simultaneous solution of ordinary differential equations and the associated first-order parametric sensitivity equations, yielding the ODE solution vector
y
_(
t
) and the first-order sensitivity coefficients with respect to equation parameters
p
_, ∂
y
_(
t
)/∂
p
_. ODESSA is a modification of the widely disseminated initial-value solver LSODE, and retains many of the same operational features. Standard program usage and optional capabilities, installation, and verification considerations are addressed herein.
Retraining teachers to teach high school computer science
Authors: Poirot James,L. , Taylor Harriet,G. , Norris Cathleen,A.
Published: July 2002

The national trends regarding the retraining of secondary school teachers in a computer science discipline are examined. Recommendations and guidelines are offered in this ACM/IEEE Task Force report.
Comparison of analysis techniques for information requirement determination
Authors: Yadav Surya,B. , Bravoco Ralph,R. , Chatfield Akemi,T. , Rajkumar T. M.
Published: July 2002

A comparison of systems analysis techniques, the Data Flow Diagram (DFD) and part of the Integrated Definition Method (IDEFo), is done using a new developmental framework.
Bound hierarchies for multiple-class queuing networks
Authors: Eager Derek L. , Sevcik Kenneth C.
Published: July 2002

An algorithm for computing bounds on the performance measures of multiple-class, product-form queuing networks is presented. The algorithm offers the user a hierarchy of bounds with differing accuracy levels and computational cost requirements. Unlike previously proposed bounding algorithms, the algorithm is applicable to all of the types of product-form queuing networks that are commonly used in computer system and computer-communication network applications.
Secure password-based cipher suite for TLS
Authors: Steiner Michael , Buhler Peter , Eirich Thomas , Waidner Michael
Published: July 2002

SSL is the de facto standard today for securing end-to-end transport on the Internet. While the protocol itself seems rather secure, there are a number of risks that lurk in its use, for example, in web banking. However, the adoption of password-based key-exchange protocols can overcome some of these problems. We propose the integration of such a protocol (DH-EKE) in the TLS protocol, the standardization of SSL by IETF. The resulting protocol provides secure mutual authentication and key establishment over an insecure channel. It does not have to resort to a PKI or keys and certificates stored on the users computer. Additionally, its integration in TLS is as minimal and non-intrusive as possible.
A highly scalable and effective method for metasearch
Authors: Meng Weiyi , Wu Zonghuan , Yu Clement , Li Zhuogang
Published: July 2002

A metasearch engine is a system that supports unified access to multiple local search engines. Database selection is one of the main challenges in building a large-scale metasearch engine. The problem is to efficiently and accurately determine a small number of potentially useful local search engines to invoke for each user query. In order to enable accurate selection, metadata that reflect the contents of each search engine need to be collected and used. This article proposes a highly scalable and accurate database selection method. This method has several novel features. First, the metadata for representing the contents of all search engines are organized into a single integrated representative. Such a representative yields both computational efficiency and storage efficiency. Second, the new selection method is based on a theory for ranking search engines optimally. Experimental results indicate that this new method is very effective. An operational prototype system has been built based on the proposed approach.
On numerical solutions to one-dimensional integration problems with applications to linear light sources
Authors: Ouellette Marc J. , Fiume Eugene
Published: July 2002

Many key problems in computer graphics require the computation of integrals. Due to the nature of the integrand and of the domain of integration, these integrals seldom can be computed analytically. As a result, numerical techniques are used to find approximate solutions to these problems. While the numerical analysis literature offers many integration techniques, the choice of which method to use for specific computer graphic problems is a difficult one. This choice must be driven by the numerical efficiency of the method, and ultimately, by its visual impact on the computed image. In this paper, we begin to address these issues by methodically analyzing deterministic and stochastic numerical techniques and their application to the type of one-dimensional problems that occur in computer graphics, especially in the context of linear light source integration. In addition to traditional methods such as Gauss-Legendre quadratures, we also examine Voronoi diagram-based sampling, jittered quadratures, random offset quadratures, weighted Monte Carlo, and a newly introduced method of compounding known as a
difficulty driven compound quadrature
.We compare the effectiveness of these methods using a three-pronged approach. First, we compare the frequency domain characteristics of all the methods using periodograms. Next, applying ideas found in the numerical analysis literature, we examine the numerical and visual performance profiles of these methods for seven different one-parameter problem families. We then present results from the application of the methods for the example of linear light sources. Finally, we summarize the relative effectiveness of the methods surveyed, showing the potential power of difficulty-driven compound quadratures.
Combinatorics, complexity, and randomness
Authors: Karp Richard M.
Published: July 2002

The 1985 Turing Award winner presents his perspective on the development of the field that has come to be called theoretical computer science.
Effects of job loading policies for multiprogramming systems in processing a job stream
Authors: Kameda Hisao
Published: July 2002

The scheduling of jobs for multiprogramming systems includes the selection of jobs to be loaded into memory (job loading policy or memory schedule) and the scheduling for CPU processing (CPU schedule). There has been a successful empirical claim for the optimal CPU schedule; its optimality has been proved in a Markovian model of job-stream processing that uses the first-come-first-loaded (FCFL) job loading policy. We extend this model to gain insight into the effects of job loading policies.

The model studied consists of an input stream of jobs of two classes and a multiple-resource system (the model of a multiprogramming system) with a stack for waiting jobs. The system consists of a finite amount of memory and a cyclic queue of a single (CPU) server station and a multiple (I/O) server station. The values of parameters describing each class of jobs are distinct except the mean I/O service time and the amount of memory required. The estimate of the maximum processing capacity (throughput bound) of the system is obtained and is shown to be achieved by the combination of the empirically claimed optimal CPU schedule and a job loading policy whereby the set of jobs in memory is kept to be (nearly) balanced with respect to the job stream. Furthermore, we show that the job loading policies independent of the system status have no improvement over the FCFL policy.

Our investigation, supported by numerical calculations, suggests that much more care may be needed in implementing the job loading policy that aims at the optimal processing capacity than in implementing the optimal CPU schedule. This agrees with what has been conjectured on the basis of empirical studies.
Context and orientation in hypermedia networks
Authors: Utting Kenneth , Yankelovich Nicole
Published: July 2002

The core of hypermedia's power lies in the complex networks of links that can be created within and between documents. However, these networks frequently overwhelm the user and become a source of confusion. Within Intermedia, we have developed the Web View-a tool for viewing and navigating such networks with a minimum of user confusion and disorientation. The key factors in the Web View's success are a display that combines a record of the user's path through the network with a map of the currently available links; a scope line that summarizes the number of documents and links in the network; and a set of commands that permit the user to open documents directly from the Web View.
An algebra for structured office documents
Authors: Güting Ralf Hartmut , Zicari Roberto , Choy David M.
Published: July 2002

We describe a data model for structured office information objects, which we generically call “documents,” and a practically useful algebraic language for the retrieval and manipulation of such objects. Documents are viewed as hierarchical structures; their layout (presentation) aspect is to be treated separately. The syntax and semantics of the language are defined precisely in terms of the formal model, an extended relational algebra.

The proposed approach has several new features, some of which are particularly useful for the management of office information. The data model is based on nested sequences of tuples rather than nested relations. Therefore, sorting and sequence operations and the explicit handling of duplicates can be described by the model. Furthermore, this is the first model based on a many-sorted instead of a one-sorted algebra, which means that atomic data values as well as nested structures are objects of the algebra. As a consequence, arithmetic operations, aggregate functions, and so forth can be treated inside the model and need not be introduced as query language extensions to the model. Many-sorted algebra also allows arbitrary algebra expressions (with Boolean result) to be admitted as selection or join conditions and the results of arbitrary expressions to be embedded into tuples. In contrast to other formal models, this algebra can be used directly as a rich query language for office documents with precisely defined semantics.
The periodic balanced sorting network
Authors: Dowd Martin , Perl Yehoshua , Rudolph Larry , Saks Michael
Published: July 2002

A periodic sorting network consists of a sequence of identical blocks. In this paper, the periodic balanced sorting network, which consists of log
n
blocks, is introduced. Each block, called a balanced merging block, merges elements on the even input lines with those on the odd input lines.

The periodic balanced sorting network sorts
n
items in
O
([log
n
]
2
) time using (
n
/2)(log
n
)
2
comparators. Although these bounds are comparable to many existing sorting networks, the periodic structure enables a hardware implementation consisting of only one block with the output of the block recycled back as input until the output is sorted. An implementation of our network on the shuffle exchange interconnection model in which the direction of the comparators are all identical and fixed is also presented.
Distributed form management
Authors: Hämmäinen Heikki , Eloranta Eero , Alasuvanto Jari
Published: July 2002

An open architecture for distributed form management is described. The model employs object-orientation in describing organizational units as well as individual users as entities with uniform external interfaces. Each entity is represented by an autonomous
user agent
which operates on local and migrating
forms
. The form concept encapsulates data, layout, and rules into a unified object which is the basic unit of presentation, processing, storage, and communication. All functionality of the system appears in rules of form classes and all data in instances of these form classes. This approach applies the techniques of computer supported cooperative work to provide a flexible mechanism for interpersonal, intraoffice, and interoffice procedures. The main challenge is to organize the collaboration without affecting the autonomy of individual user agents. In this respect, the contribution of the model is the mechanism for form migration. The dynamic integration of forms into different agents is solved with the coordinated interchange of form classes. A specific inheritance scheme provides the desired flexibility by separating the interrelated private and public form operations within each agent. The paper first describes the architecture by starting from a single agent and moving progressively towards a set of cooperating agents. Then an agent implementation called PAGES is described, experiences reported, and the open issues discussed. A typical distributed ordering procedure is used as an example throughout the text.
Personal computing: compuvision or teleputer
Authors: Press Larry
Published: July 2002

Historically, the computer and communication industries have been separate, although both worked with electronically encoded information and shared similar technology. The regulations that kept computing and communication apart began to crumble in 1956 when the FCC ruled that Hush-a-Phone could attach equipment to the AT&T network under special circumstances. In 1959 they opened a portion of the microwave spectrum, and the 1968 Carter-phone case allowed all kinds of equipment to be tied to the network. Today, IBM is in the communication business and AT&T markets computers, but many feel that the distinction among computing, communication, news, and entertainment industries will blur or disappear.

The question is, who will lead the charge—the computer companies, entertainment companies, toy companies, or phone companies? To put it another way, will the home computer swallow up the television set or will the television set become a computer in disguise?

Not surprisingly, computer companies and entertainment companies have different answers to this question, and the debate was brought into focus by announcements at the Fifth Microsoft International CD-ROM Conference and Exposition. Let us look at the question of the home computer versus the smart TV and then come back to some of the other interesting announcements at the show and the current state of multimedia applications.
Inside risks: risks in computerized elections
Authors: Neumann Peter G.
Published: July 2002

Background: Errors and alleged fraud in computer-based elections have been recurring Risks Forum themes. The state of the computing art continues to be primitive. Punch-card systems are seriously flawed and easily tampered with, and still in widespread use. Direct recording equipment is also suspect, with no ballots, no guaranteed audit trails, and no real assurances that votes cast are properly recorded and processed.
Multimedia document presentation, information extraction, and document formation in MINOS: a model and a system
Authors: Christodoulakis S. , Theodoridou M. , Ho F. , Papa M. , Pathria A.
Published: July 2002

MINOS is an object-oriented multimedia information system that provides integrated facilities for creating and managing complex multimedia objects. In this paper the model for multimedia documents supported by MINOS and its implementation is described. Described in particular are functions provided in MINOS that exploit the capabilities of a modern workstation equipped with image and voice input-output devices to accomplish an active multimedia document presentation and browsing within documents. These functions are powerful enough to support a variety of office applications. Also described are functions provided for the extraction of information from multimedia documents that exist in a large repository of information (multimedia document archiver) and functions that select and transform this information. Facilities for information sharing among objects of the archiver are described; an interactive multimedia editor that is used for the extraction and interactive creation of new information is outlined; finally, a multimedia document formatter that is used to synthesize a new multimedia document from extracted and interactively generated information is presented.

This prototype system runs on a SUN-3 workstation running UNIX'". An Instavox, directly addressable, analog device is used to store voice segments.
TRANSCRIPTIONAL CONTROL OF MUSCLE DEVELOPMENT BY MYOCYTE ENHANCER FACTOR-2 (MEF2) PROTEINS
Authors: Black Brian L. , Olson Eric N.
Published: July 2002

▪ Abstract  Metazoans contain multiple types of muscle cells that share several common properties, including contractility, excitability, and expression of overlapping sets of muscle structural genes that mediate these functions. Recent biochemical and genetic studies have demonstrated that members of the myocyte enhancer factor-2 (MEF2) family of MADS (MCM1, agamous, deficiens, serum response factor)-box transcription factors play multiple roles in muscle cells to control myogenesis and morphogenesis. Like other MADS-box proteins, MEF2 proteins act combinatorially through protein-protein interactions with other transcription factors to control specific sets of target genes. Genetic studies in Drosophila have also begun to reveal the upstream elements of myogenic regulatory hierarchies that control MEF2 expression during development of skeletal, cardiac, and visceral muscle lineages. Paradoxically, MEF2 factors also regulate cell proliferation by functioning as endpoints for a variety of growth factor-regulated intracellular signaling pathways that are antagonistic to muscle differentiation. We discuss the diverse functions of this family of transcription factors, the ways in which they are regulated, and their mechanisms of action.
Molecular Recognition and Response in Pollen and Pistil Interactions
Authors: McCubbin Andrew G. , Kao Teh-hui
Published: July 2002

▪ Abstract  Many bisexual flowering plants possess a reproductive strategy called self-incompatibility (SI) that enables the female tissue (the pistil) to reject self but accept non-self pollen for fertilization. Three different SI mechanisms are discussed, each controlled by two separate, highly polymorphic genes at the S-locus. For the Solanaceae and Papaveraceae types, the genes controlling female function in SI, the S-RNase gene and the S-gene, respectively, have been identified. For the Brassicaceae type, the gene controlling male function, SCR/SP11, and the gene controlling female function, SRK, have been identified. The S-RNase based mechanism involves degradation of RNA of self-pollen tubes; the S-protein based mechanism involves a signal transduction cascade in pollen, including a transient rise in [Ca2+]i and subsequent protein phosphorylation/dephosphorylation; and the SRK (a receptor kinase) based mechanism involves interaction of a pollen ligand, SCR/SP11, with SRK, followed by a signal transduction cascade in the stigmatic surface cell.
NONCOALESCENCE AND NONWETTING BEHAVIOR OF LIQUIDS
Authors: Neitzel G. Paul , Dell'Aversana Pasquale
Published: July 2002

▪ Abstract  We examine situations in which two droplets of the same liquid may come into apparent contact without coalescing or in which a droplet that normally wets a surface may deform against it without actually wetting it. The focus of this review is on cases driven by hydrodynamic lubrication, the lubricant provided either by surface motion or by evaporation.
Escherichia coliO157:H7 Gastroenteritis and the Hemolytic Uremic Syndrome: An Emerging Infectious Disease
Authors: Besser, MD Richard E. , Griffin, MD Patricia M. , Slutsker, MD, MPH Laurence
Published: July 2002

Escherichia coli O157:H7 is an increasingly common cause of a variety of illnesses, including bloody diarrhea and the hemolytic uremic syndrome. This emerging infectious agent was first identified in 1982 and has been isolated with increasing frequency since then. This chapter reviews the epidemiology, clinical spectrum, diagnosis, treatment, and prevention of infections with E. coli O157:H7.
THE ROLE OF PLANT CLINICS IN PLANT DISEASE DIAGNOSIS AND EDUCATION IN DEVELOPING COUNTRIES
Authors: Ausher Reuben , Ben-Ze'ev Israel S. , Black Robert
Published: July 2002

▪ Abstract  The scarcity of literature in the realm of plant clinics operating in the developing world brought us to the decision to perform a survey in non-OECD countries in Africa, Asia and Oceania, Latin America and the Caribbean, and in central and southern Europe. Forty-one completed questionnaires that refer to 79 plant clinics were returned. The best-equipped clinics are operated by the international research bodies. By and large, this review shows that considerable progress has been achieved in the physical development of plant clinics in developing countries and in staffing them with well-trained personnel. Not surprisingly, however, many inadequacies and inconsistencies still need to be addressed before clinics can fully play their part in providing plant protection services to their clients. Success and constraining indicators in the diagnostic performance of the clinics are identified. A model of the‘ideal plant clinic’ is suggested.
LANGUAGE ACQUISITION: The Acquisition of Linguistic Structure in Normal and Special Populations
Authors: McDonald Janet L.
Published: July 2002

▪ Abstract  This review examines how language learners master the formal structure of their language. Three possible routes to the acquisition and mastery of linguistic structure are investigated: (a) the use of prosodic and phonological information, which is imperfectly correlated with syntactic units and linguistic classes; (b) the use of function words to syntactically classify co-occurring words and phrases, and the effect of location of function-word processing on structural mastery; and (c) the use of morphology internal to lexical items to determine language structure, and the productive recombination of these subunits in new items. Evidence supporting these three routes comes from normal language acquirers and from several special populations, including learners given impoverished input, learners with Williams syndrome, specific language-impaired learners, learners with Down syndrome, and late learners of first and second languages. Further evidence for the three routes comes from artificial language acquisition experiments and computer simulations.
YOUTH ACCESS TO TOBACCO: Policies and Politics
Authors: Forster Jean L. , Wolfson Mark
Published: July 2002

▪ Abstract  The late 1980s marked the beginning of a sea change in research and intervention on tobacco use by young people, when the first studies were published demonstrating the ease with which adolescents could purchase cigarettes. Since then concern with the commercial availability of tobacco products to youth has grown, becoming deeply entrenched in both research and policy efforts. This paper reviews the history of restrictions on youth access to tobacco, the evidence that commercial sources of tobacco are available and important to adolescents, and the rationale for various components of policies to restrict access. We also review the recent expansion of policies addressing youth access to tobacco at all levels of government, the tobacco industry response to this expansion, and issues that have arisen as this expansion has developed.
The Macroeconomic Determinants of Health
Authors: Subramanian S. V. , Belli Paolo , Kawachi Ichiro
Published: July 2002

▪ Abstract  Why are some societies healthier than others? The consensus in development economics is that the health achievement of nations has to do with their levels of economic development. Higher per capita incomes, through steady and stable economic growth, increase a nation's capacity to purchase the necessary economic goods and services that promote health. In this paper, we review the conceptual and empirical linkages between poverty and poor health in both developing and developed countries. The empirical evidence is overwhelming that poverty, measured at the level of societies as well as individuals, is causally related to poor health of societies and individuals, respectively. Recent macroeconomic research has also drawn attention to the role of health as a form of human capital that is vital for achieving economic stability. In particular, attention has been drawn toward the ways in which unhealthy societies impede the process of economic development. However, the reciprocal connection between economic prosperity and improved health is neither automatic nor universal. Other features of society, such as the equality in the distribution of the national wealth, seem to matter as well for improving average population health and especially for reducing inequalities in health. We conclude by arguing for a need to reexamine the way in which health is conceptualized within the macroeconomic development framework.
Does Decline Make Sense? The West Indian Economy and the Abolition of the British Slave Trade
Authors: Ryden David Beck
Published: July 2002

Most historians describe the moral distaste for slavery as the sole reason for the cessation of the British slave trade. Data from the Caribbean, however, along with contemporary commentary, show that an economic crisis faced by sugar planters was critical to the timing of abolition in 1807.
Economic Change and Infant Mortality in England, 1580-1837
Authors: Schellekens Jona
Published: July 2002

Adaptation of the results from a recent family-reconstitution study of twenty-six parishes in pre-transition England reveals that long-term trends in post-neonatal mortality follow trends in a real-wage index, and that trends in neonatal mortality correlate with other economic factors. Thus, the hypothesis that infant mortality and economic performance in pre-transition England were related is consistent with the family-reconstitution data.
TechnoSphere: “Real” Time, “Artificial” Life
Authors: Prophet Jane
Published: July 2002

This paper focuses on the real-time 3D version of the artificial-life art piece TechnoSphere, a collaborative project by the author, Mark Hurry and Gordon Selley. It begins by positioning TechnoSphere's simulated landscapes in relationship to the English landscape and its tradition in painting and problematizes ideas of “the natural.” The TechnoSphere creatures are evaluated as both artificial wildlife and domesticated animals before the authors consider the relationship between creature and environment. This is followed by a comparison of the Internet and real-time versions of TechnoSphere and concludes by outlining the work-in-progress—a merging of the two systems.
Machine Head: Raoul Hausmann and the Optophone
Authors: Donguy Jacques
Published: July 2002

Dadaist Raoul Hausmann, famous for his photomontages, is perhaps less well known as a pioneer of synaesthetic machines designed to transform sound into form and vice versa—not unlike primitive computers, in fact. The author has located the patent for one such invention, artist Peter Keene's realization of which accompanies this historical account
An Alpha Revisionist Manifesto: Concept White Paper
Authors: Lichty Patrick
Published: July 2002

In the technological sector, the first development stage of a product is known as ‘Alpha’ phase. The essay posits that techno-industrial culture and the production of technological art have been superimposed to the point where artists are often indistinguishable from commercial entities trying to sell the next hype-laden device. This is also true in the case of intangible on-line art, as market and institutional forces rematerialize net and other forms of screen-based art. The combination of hype and the temporal constraints of development and production result in a milieu where professed claims seldom live up to the final product. The cycle of promotion of the ‘Next Big Thing,’ whether art, data, or consumer object, outstrips any possibility for finished products to keep pace with expectations raised by the ‘Alpha’ and ‘Beta’ prerelease stages. The result is an inordinate degree of media attention focused on ideas that are barely out of conceptual stages or ‘Alpha Revision,’ so that conceptual artists of the informational milieu must become engaged in the high-speed production of concept proposals, or ‘Alpha Revisionist’ works.
Movement and Control
Authors: Hornstein Norbert
Published: July 2002

Since the earliest days of generative grammar, control has been distinguished from raising: the latter the product of movement operations, the former the result of construal processes relating a PRO to an antecedent. This article argues that obligatory control structures are also formed by movement. Minimalism makes this approach viable by removing D-Structure as a grammatical level. Implementing the suggestion, however, requires eliminating the last vestiges of D-Structure still extant in Chomsky's (1995) version of the Minimalist Program. In particular, it requires dispensing with the θ-Criterion and adopting the view that θ-roles are featurelike in being able to license movement.
Local and Global Gating of Synaptic Plasticity
Authors: Sánchez-Montañés Manuel A. , Verschure Paul F. M. J. , König Peter
Published: July 2002

Mechanisms influencing learning in neural networks are usually investigated on either a local or a global scale. The former relates to synaptic processes, the latter to unspecific modulatory systems. Here we study the interaction of a local learning rule that evaluates coincidences of pre- and postsynaptic action potentials and a global modulatory mechanism, such as the action of the basal forebrain onto cortical neurons. The simulations demonstrate that the interaction of these mechanisms leads to a learning rule supporting fast learning rates, stability, and flexibility. Furthermore, the simulations generate two experimentally testable predictions on the dependence of backpropagating action potential on basal forebrain activity and the relative timing of the activity of inhibitory and excitatory neurons in the neocortex.
Neural Field Model of Receptive Field Restructuring in Primary Visual Cortex
Authors: Suder Katrin , Wörgötter Florentin , Wennekers Thomas
Published: July 2002

Receptive fields (RF) in the visual cortex can change their size depending on the state of the individual. This reflects a changing visual resolution according to different demands on information processing during drowsiness. So far, however, the possible mechanisms that underlie these size changes have not been tested rigorously. Only qualitatively has it been suggested that state-dependent lateral geniculate nucleus (LGN) firing patterns (burst versus tonic firing) are mainly responsible for the observed cortical receptive field restructuring. Here, we employ a neural field approach to describe the changes of cortical RF properties analytically. Expressions to describe the spatiotemporal receptive fields are given for pure feedforward networks. The model predicts that visual latencies increase nonlinearly with the distance of the stimulus location from the RF center. RF restructuring effects are faithfully reproduced. Despite the changing RF sizes, the model demonstrates that the width of the spatial membrane potential profile (as measured by the variance σ of a gaussian) remains constant in cortex. In contrast, it is shown for recurrent networks that both the RF width and the width of the membrane potential profile generically depend on time and can even increase if lateral cortical excitatory connections extend further than fibers from LGN to cortex. In order to differentiate between a feedforward and a recurrent mechanism causing the experimental RF changes, we fitted the data to the analytically derived point-spread functions. Results of the fits provide estimates for model parameters consistent with the literature data and support the hypothesis that the observed RF sharpening is indeed mainly driven by input from LGN, not by recurrent intracortical connections.
The Computational Exploration of Visual Word Recognition in a Split Model
Authors: Shillcock Richard , Monaghan Padraic
Published: July 2002

We argue that the projection of the visual field to the cortex constrains and informs the modeling of visual word recognition. On the basis of anatomical and psychological evidence, we claim that the higher-level cognition involved in word recognition does not completely transcend initial foveal splitting. We present a schematic connectionist model of word recognition that instantiates the precise splitting of the visual field and the contralateral projection of the two hemifields. We explore the special nature of the exterior (i.e., first and last) letters of words in reading. The model produces the correct behavior spontaneously and robustly. We analyze this behavior of the model with respect to words and random patterns and conclude that the systematic division of the visual input has predictable, general informational consequences and is chiefly responsible for the exterior letters effect.
Orientation, Scale, and Discontinuity as Emergent Properties of Illusory Contour Shape
Authors: Williams Lance R. , Thornber Karvel K.
Published: July 2002

A recent neural model of illusory contour formation is based on a distribution of natural shapes traced by particles moving with constant speed in directions given by Brownian motions. The input to that model consists of pairs of position and direction constraints, and the output consists of the distribution of contours joining all such pairs. In general, these contours will not be closed, and their distribution will not be scaleinvariant. In this article, we show how to compute a scale-invariant distribution of closed contours given position constraints alone and use this result to explain a well-known illusory contour effect.
Redistribution of Synaptic Efficacy Supports Stable Pattern Learning in Neural Networks
Authors: Carpenter Gail A. , Milenova Boriana L.
Published: July 2002

Markram and Tsodyks, by showing that the elevated synaptic efficacy observed with single-pulse long-term potentiation (LTP) measurements disappears with higher-frequency test pulses, have critically challenged the conventional assumption that LTP reflects a general gain increase. This observed change in frequency dependence during synaptic potentiation is called redistribution of synaptic efficacy (RSE). RSE is here seen as the local realization of a global design principle in a neural network for pattern coding. The underlying computational model posits an adaptive threshold rather than a multiplicative weight as the elementary unit of long-term memory. A distributed instar learning law allows thresholds to increase only monotonically, but adaptation has a bidirectional effect on the model postsynaptic potential. At each synapse, threshold increases implement pattern selectivity via a frequency-dependent signal component, while a complementary frequency-independent component nonspecifically strengthens the path. This synaptic balance produces changes in frequency dependence that are robustly similar to those observed by Markram and Tsodyks. The network design therefore suggests a functional purpose for RSE, which, by helping to bound total memory change, supports a distributed coding scheme that is stable with fast as well as slow learning. Multiplicative weights have served as a cornerstone for models of physiological data and neural systems for decades. Although the model discussed here does not implement detailed physiology of synaptic transmission, its new learning laws operate in a network architecture that suggests how recently discovered synaptic computations such as RSE may help produce new network capabilities such as learning that is fast, stable, and distributed.
Predicting the Distribution of Synaptic Strengths and Cell Firing Correlations in a Self-Organizing, Sequence Prediction Model
Authors: Amarasingham Asohan , Levy William B.
Published: July 2002

This article investigates the synaptic weight distribution of a selfsupervised, sparse, and randomly connected recurrent network inspired by hippocampal region CA3. This network solves nontrivial sequence prediction problems by creating, on a neuron-by-neuron basis, special patterns of cell firing called local context units. These specialized patterns of cell firing—possibly an analog of hippocampal place cells—allow accurate prediction of the statistical distribution of synaptic weights, and this distribution is not at all gaussian. Aside from the majority of synapses that are, at least functionally, lost due to synaptic depression, the distribution is approximately uniform. Unexpectedly, this result is relatively independent of the input environment, and the uniform distribution of synaptic weights can be approximately parameterized based solely on the average activity level. Next, the results are generalized to other cell firing types (frequency codes and stochastic firing) and place cell-like firing distributions. Finally, we note that our predictions concerning the synaptic strength distribution can be extended to the distribution of correlated cell firings. Recent published neurophysiological results are consistent with this extension.
The Brazilian Group for Computer Music Research: A Proto-History
Authors: Palombini Carlos
Published: July 2002

The Brazilian Group for Computer Music Research (NUCOM) has become renowned for its annual Brazilian Symposium on Computer Music. The author recounts the group's proto-history-the period of the 1970s and 1980s-with particular reference to the early works of Aluizio Arcela and Eduardo Miranda. The author continues his discussion to focus on NUCOM, which began to take shape in 1993 when Miranda and Geber Ramalho (one of Arcela's students) met in Paris and decided to launch a discussion list on the Web. The following year, Maurício Loureiro chaired the First Brazilian Symposium on Computer Music, affiliating NUCOM to the Brazilian Computer Society (SBC).
A Convergence Analysis of Unconstrained and Bound Constrained Evolutionary Pattern Search
Authors: Hart William E.
Published: July 2002

We present and analyze a class of evolutionary algorithms for unconstrained and bound constrained optimization on Rn: evolutionary pattern search algorithms (EPSAs). EPSAs adaptively modify the step size of the mutation operator in response to the success of previous optimization steps. The design of EPSAs is inspired by recent analyses of pattern search methods. We show that EPSAs can be cast as stochastic pattern search methods, and we use this observation to prove that EPSAs have a probabilistic, weak stationary point convergence theory. This convergence theory is distinguished by the fact that the analysis does not approximate the stochastic process of EP-SAs, and hence it exactly characterizes their convergence properties.
Economic Impact of Aluminum‐Intensive Vehicles on the U.S. Automotive Recycling Infrastructure
Authors: Boon Jane E. , Isaacs Jacqueline A. , Gupta Surendra M.
Published: July 2002

The use of aluminum alloys in automobile production is growing as automakers strive to lower vehicle fuel consumption and reduce emissions by substituting aluminum for steel. The current recycling infrastructure for end‐of‐life vehicles is mature, profitable, and well suited to steel‐intensive vehicles; increased use of cast and wrought aluminum, however, will present new challenges and opportunities to the disassembler and shredder, who now comprise the first stages of the vehicle recycling infrastructure.

Using goal programming techniques, a model of the auto recycling infrastructure is used to assess the materials streams and process profitabilities for several different aluminum‐intensive vehicle (AIV) processing scenarios. The first case simulates the processing of an AIV in the current recycling infrastructure. Various changes to the initial case demonstrate the consequences to the disassembler and shredder profitabilities whenever the price of nonferrous metals changes; greater fractions of the vehicle are removed as parts; the parts removed by the disassembler have increased aluminum content; the quantity of polymer removed by the disassembler is increased; the disassembly costs increase; the disposal costs for shredder residue and hazardous materials increase; the shredder processing costs increase; and different AIV designs are considered. These profits are also compared to those achieved for a steel unibody vehicle to highlight the impact of introducing AIVs into the existing infrastructure. Results indicate that the existing infrastructure will be able to accommodate AIVs without economic detriment.
Environmental History, Political Economy and Change: Frameworks and Tools for Research and Analysis
Authors: Lipschutz Ronnie D.
Published: July 2002

This article addresses questions of method, focus and research strategy in environmental history and political economy for policy analysis and policy-making. While most environmental history is seen as having to do with landscapes past and how they got that way, environmental history can also have practical contemporary applications. By coming to understand the sources and origins of environmental degradation, and the patterns of social organization that led to them, we may be better positioned to foster environmental protection and conservation in ways that may resolve and/or support local efforts around the world. Such studies can help to address conflicts that arise over conservation policies, especially when these studies illuminate the origins and historical trajectories of places, and provide insights into ways of working with, rather than against, local cultures, knowledges, and social arrangements.
LE SPECTACLE DES LETTRES, COMÉDIE DE CALLIAS
Authors: Ruijgh C.J.
Published: July 2002

SOMMAIRE: § 1. Les trois fragments en trimètres iambiques.-§ 2. La parodos.-§ 3. Les noms de lettres dans le Spectacle.-§ 4. Le Marcianus A représente l'abrégé en 15 livres du texte en 30 livres d'Athénée.-§ 5. L'épitomé du texte déjà abrégé; les procédés de l'Epitomator et du Breviator.- § 6. Le problème de la date du Spectacle et de l'attribution au poète comique Callias.-§ 7. La structure métrique et prosodique des trimètres du Spectacle: structure du trimètre tragique.-§ 8. Le Spectacle a la forme d'une tragédie; date: environ 435.-§ 9. Le contenu du Spectacle.-§ 10. La mention du Spectacle au livre VII (275f11-276a6).-§ 11. La version abrégée de ce texte dans l'Épitomé.-§ 12-13. La mention du Spectacle au début de la digression sur les devinettes au livre X (448b3-c3).-§ 14. Le passage sur le prologue du Spectacle (453c3-d4).-§ 15. Observations sur 453c3-9.- § 16. Observations sur 453d1-4 = Fragment I.-§ 17. Le passage sur le choeur du Spectacle (453d5-f1).-§ 18. La reconstruction de la parodos.- § 19. Observations sur 453d5-e3.-§ 20. Observations sur 453e3-6 et e11-f1.-§ 21. L'emploi de mélodies divérentes pour la strophe et l'antistrophe correspondante dans les tragédies antérieures à 431 av. J.-C., dans les comédies, dans la grande lyrique chorale et dans la lyrique monodique.-§ 22. Excursus sur les rapports entre les mélodies du chant traditionnel et les contours mélodiques du langage parlé.-§ 23. Les mélodies de la tragédie ancienne, de la lyrique chorale et de la lyrique monodique.- § 24. Les innovations radicales du dithyrambe 'moderne' adoptées par Euripide.-§ 25. Le passage de Denys d'Halicarnasse sur la subordination des paroles à la mélodie et au rythme musicaux.-§ 26. Observations sur 453e6-10. L'élision en fin de vers.-§ 27. Le passage sur l'emploi syllabique des lettres vocaliques à elles seules (453f1-454a1).-§ 28. Observations sur 453f1-5.-§ 29. Observations sur 453f6-454a1 = Fragment II.-§ 30. Le passage sur la mention des formes des lettres pour indiquer un mot (454a2-9).-§ 31. Observations sur 454a2-9 (454a5-9 = Fragment III).- § 32. Le texte de 453c2-454a9 dans l'Épitomé.-§ 33-34. Les imitations du Spectacle (454a10-455b7).-§ 35. Conclusion.
Variation in reproductive capacity and virulence on different genotypes and resistance genes of Triticeae, in the cereal cyst nematode species complex
Authors: Fradj Makram Bel Hadj , Jahier Joseph , Bekal Sadia , Nicol Julie , Gauthier Jean-Pierre , Mokabli Aïssa , Rivoal Roger , Yahyaoui Amor , Valette Sylvie
Published: July 2002

Two sets of experiments in 1998 and 1999 studied the (a)virulence status of 14 populations of Heterodera avenae, and two populations each of H. filipjevi and H. latipons towards the resistance genes and genotypes of Triticeae, presently known to be resistant to H. avenae, the main species of the cereal cyst nematode (CCN) species complex. Susceptible controls were Triticum aestivum cv. Arminda and Triticum turgidum cv. Cham1. Even in controlled experimental conditions, host responses differed between replicates in the same test and between consecutive tests for unexplained reasons. In spite of that, it has been confirmed that several of these CCN populations differ in their intrinsic capacity to reproduce, and this has to be taken into account in resistance screening. Consequently, the (a)virulence status of a CCN population is better established by a qualitative demarcation between resistant and susceptible plant genotypes based on an average of one cyst limit per plant. The matrix inferred from such a classification of host responses of pooled 1998 and 1999 data showed a complex distribution of avirulent and virulent phenotypes in these CCN populations which seems to arise from a mosaic-like evolution. The more or less wide virulence spectrum shown by this complex of populations and species is discussed in relation to their phylogenetic relationships. Correspondence factor analysis of the pooled data demonstrated a geographical demarcation between several populations of H. avenae and the representatives of H. filipjevi and H. latipons for their (a)virulence to either Cre1 or Cre3 genes and T. aestivum AUS4930 genotype. This could reveal local or regional selection of new pathotypes, more particularly in H. avenae. Genetic introgression to improve resistance to these nematodes in both bread and durum wheats is discussed for regional and global applications.
Diagenetic history of Lower Palaeozoic sediments in Pomerania (northern Poland), traced across the Teisseyre–Tornquist tectonic zone using mixed– layer illite– smectite
Authors: Środoń J. , Clauer N.
Published: July 2002

Mixed-layer illite-smectite from Lower Palaeozoic sedimentary rocks, on both sides of the Teisseyre–Tornquist tectonic zone (TTZ) in northern Poland, was studied by X-ray diffraction and dated by K-Ar means.

The percentage of smectite layers in illite-smectite (%S) indicates maximum palaeotemperatures of 125–135°C at the surface of Lower Palaeozoic rocks on the craton (NE of TTZ), and 110 to ≤180°C in different tectonic blocks to the SW of TTZ (area of Caledonian consolidation). The vertical changes in the %S indicate that the maximum palaeotemperatures were reached before Permian time on the craton, and before Jurassic, Triassic, Permian or Carboniferous periods but after the beginning of Devonian time in the Caledonian zone. The K—Ar ages of bentonites indicate that the maximum palaeotemperatures were reached by 370—390 Ma or even slightly earlier (Middle—late Devonian). A maximum of 3—6 km of Silurian–Devonian cover on the craton and in the TTZ is suggested by the data.