bluuebunny/crossref_metadata_2025 huggingface dataset:
On coordination reduction and sentence analysis
Authors: Petrick Stanley R. , Postal Paul M. , Rosenbaum Peter S.
Published: July 2002

A class of coordination phenomena in natural languages is considered within the framework of transformational theory. To account for these phenomena it is proposed that certain machinery be added to the syntactic component of a transformational grammar. This machinery includes certain rule schemata, the conditions under which they are to be applied, and conditions determining the sequence of subtrees on which they are to be performed. A solution to the syntactic analysis problem for this class of grammars is outlined. Precise specification of both the generative procedure of this paper and its inverse is given in the form of LISP function definitions.
A recursive relation for the determinant of a pentadiagonal matrix
Authors: Sweet Roland A.
Published: July 2002

A recursive relation, relating leading principal minors, is developed for the determinant of a pentadiagonal matrix. A numerical example is included to indicate its use in calculating eigenvalues.
Nonlinear extrapolation and two-point boundary value problems
Authors: Bellman Richard , Kagiwada Harriet , Kalaba Robert
Published: July 2002

It is suggested that the convergence properties of the usual Picard successive approximation scheme may be improved through use of nonlinear extrapolation techniques. A numerical example is provided.
Logical models of argument
Authors: Chesñevar Carlos Iván , Maguitman Ana Gabriela , Loui Ronald Prescott
Published: July 2002

Logical models of arguement formalize commonsense reasoning while taking process and computation seriously. This survey discusses the main ideas that characterize different logical models of argument. It presents the formal features of a few features of a few main approaches to the modeling of argumentation. We trace the evolution of argumentation from the mid-1980s, when argument systems emerged as an alternative to nonmonotonic formalisms based on classical logic, to the present, as argument in embedded in different complex systems for real-world applications, and allow more formal work to be done in different areas, such as AI and Law, case-based reasoning and negotiation among intelligent agents.
Acceptance trees
Authors: Hennessy M.
Published: July 2002

A simple model, AT, for nondeterministic machines is presented which is based on certain types of trees. A set of operations, Σ, is defined over AT and it is shown to be completely characterized by a set of inequations over Σ. AT is used to define the denotational semantics of a language for defining nondeterministic machines. The significance of the model is demonstrated by showing that this semantics reflects an intuitive operational semantics of machines based on the idea that machines should only be differentiated if there is some experiment that differentiates between them.
A vertex-allocation theorem for resources in queuing networks
Authors: Tripathi Satish K. , Woodside C. Murray
Published: July 2002

A product-form queuing network with multiple open and closed chains is considered. Some of the closed chains, which have a single customer each, require allocation of resources in the network so as to maximize a weighted throughput performance criterion. Chains with more than one customer can be decomposed into many chains of one customer each. It is proved that an optimal allocation of resources lies on a vertex (extreme points) of the set of feasible allocations. This considerably reduces the search space for an optimal allocation. Applications of this result in distributed computing are discussed.
An algorithm for multidimensional data clustering
Authors: Wan S. J. , Wong S. K. M. , Prusinkiewicz P.
Published: July 2002

A new divisive algorithm for multidimensional data clustering is suggested. Based on the minimization of the sum-of-squared-errors, the proposed method produces much smaller quantization errors than the median-cut and mean-split algorithms. It is also observed that the solutions obtained from our algorithm are close to the local optimal ones derived by the k-means iterative procedure.
A case for dynamic view management
Authors: Kotidis Yannis , Roussopoulos Nick
Published: July 2002

Materialized aggregate views represent a set of redundant entities in a data warehouse that are frequently used to accelerate On-Line Analytical Processing (OLAP). Due to the complex structure of the data warehouse and the different profiles of the users who submit queries, there is need for tools that will automate and ease the view selection and management processes. In this article we present DynaMat, a system that manages dynamic collections of materialized aggregate views in a data warehouse. At query time, DynaMat utilizes a dedicated disk space for storing computed aggregates that are further engaged for answering new queries. Queries are executed independently or can be bundled within a multiquery expression. In the latter case, we present an execution mechanism that exploits dependencies among the queries and the materialized set to further optimize their execution. During updates, DynaMat reconciles the current materialized view selection and refreshes the most beneficial subset of it within a given maintenance window. We show how to derive an efficient update plan with respect to the available maintenance window, the different update policies for the views and the dependencies that exist among them.
Algorithm 814
Authors: Smith David M.
Published: July 2002

A collection of Fortran-90 routines for evaluating the gamma function and related functions using the FM multiple-precision arithmetic package.
Optimum combinations of sorting and merging
Authors: Manacher G. K. , Bui T. D. , Mai T.
Published: July 2002

In 1979, G. K. Manacher showed that the Ford-Johnson sorting algorithm [FJA], acting on
t
real numbers, can be beaten for an infinite set of values
t
. These values form a partial cover of constant density not close to 1 over an initial sequence of each
band
running from

u
k

= ⌊(4/3)2
k
⌋ to

u
k
+l

- 1. This early result depended on showing that the Hwang-Lin merging algorithm [HLA], merging
m
elements with
n
,
m
≠
n
, could be surpassed by
cm
comparisons, where
c
is an arbitrary small positive constant.

In this paper, it is shown that the FJA can be beaten for a set of integers
of asymptotic density
1 under the greatly weakened assumption that the HLA can be surpassed by only (1/2 + ϵ)log
m
comparisons, with ϵ a small positive constant. The even weaker assumption that
no
improvement in the HLA exists, but that an isolated value
t
o
exists for which the FJA can be surpassed by only (1 + ϵ)log
t
o
comparisons yields the same result. Only for a set of “refractory” integers of size about
t
1/2
in the neighborhood of each

u
k

does the FJA fail to be beaten.

All these results depend on a new technique for obtaining optimum sort-merge sequences for best-possible sorting given a merging method. The technique turns out to be amenable to precise asymptotic analysis. When the technique is applied using the most powerful known merging algorithm [Christen's], the density mentioned above is still 1, but islands of refractory points still remain, this time forming sets provably of size Θ(log
2
t
) in the neighborhood of each

u
k

.

It is shown that if “information theoretic” merging were achievable, the FJA could be beaten for all
t
>
u
10
= 1365. From these results and a few others, we adduce evidence in support of our main conjecture: that even
optimum
combinations of
optimum
merging and Ford-Johnson sorting will not beat the FJA when
t
=

u
k

, but will instead produce refractory regions of size Θ(log
2
t
) in the neighborhood of each

λ

.
Minimal and complete word unification
Authors: Jaffar Joxan
Published: July 2002

The fundamental satisfiability problem for word equations has been solved recently by Makanin. However, this algorithm is purely a decision algorithm. The main result of this paper solves the complementary problem of generating the set of all solutions. Specifically, the algorithm in this paper generates, given a word equation, a minimal and complete set of unifiers. It stops if this set is finite.
IMAGES OF NATURE AND SOCIETY IN AMAZONIAN ETHNOLOGY
Authors: Viveiros de Castro Eduardo
Published: July 2002

▪ Abstract  This review discusses changes in Amazonian indigenous anthropology since the synthesis presented in the Handbook of South American Indians. The past few years have seen the emergence of an image of Amazonia characterized by a growing emphasis on the complexity of indigenous social formations and the ecological diversity of the region. This new image of society and nature is taking shape in a theoretical context characterized by the synergistic interaction between structural and historical approaches, by an attempt to go beyond monocausal explanatory models (whether naturalistic or culturalistic) in favor of a dialectical view of the relations between society and nature, and by hopes of a “new synthesis” that could integrate the knowledge accumulated in the fields of human ecology, social anthropology, archeology, and history.
Ancient DNA Studies in Physical Anthropology
Authors: O'Rourke Dennis H. , Hayes M. Geoffrey , Carlyle Shawn W.
Published: July 2002

▪ Abstract  Nucleic acids are preserved in prehistoric samples under a wide range of depositional environments. The development of new molecular methods, especially the polymerase chain reaction, has made possible the recovery and manipulation of these molecules, and the subsequent molecular genetic characterization of the ancient samples. The analysis of ancient (a)DNA is complicated by the degraded nature of ancient nucleic acids, as well as the presence of enzymatic inhibitors in aDNA extracts. We review aspects of ancient DNA preservation, a variety of methods for the extraction and amplification of informative DNA segments from ancient samples, and the difficulties encountered in documenting the authenticity of ancient DNA template. Studies using aDNA to address questions in human population history or human evolution are reviewed and discussed. Future prospects for the field and potential directions for future aDNA research efforts in physical anthropology are identified.
THE 1-DEOXY-D-XYLULOSE-5-PHOSPHATE PATHWAY OF ISOPRENOID BIOSYNTHESIS IN PLANTS
Authors: Lichtenthaler Hartmut K.
Published: July 2002

▪ Abstract  In plants the biosynthesis of prenyllipids and isoprenoids proceeds via two independent pathways: (a) the cytosolic classical acetate/mevalonate pathway for the biosynthesis of sterols, sesquiterpenes, triterpenoids; and (b) the alternative, non-mevalonate 1-deoxy-d-xylulose-5-phosphate (DOXP) pathway for the biosynthesis of plastidic isoprenoids, such as carotenoids, phytol (a side-chain of chlorophylls), plastoquinone-9, isoprene, mono-, and diterpenes. Both pathways form the active C5-unit isopentenyl diphosphate (IPP) as the precursor from which all other isoprenoids are formed via head-to-tail addition. This review summarizes current knowledge of the novel 1-deoxy-d-xylulose-5-phosphate (DOXP) pathway for isopentenyl diphosphate biosynthesis, apparently located in plastids. The DOXP pathway of IPP formation starts from D-glyceraldehyde-3-phosphate (GA-3-P) and pyruvate, with DOXP-synthase as the starting enzyme. This pathway provides new insight into the regulation of chloroplast metabolism.
ON THE CHARACTERISTICS OF FUNCTIONAL MAGNETIC RESONANCE IMAGING OF THE BRAIN
Authors: Ogawa S. , Menon R. S. , Kim S.-G. , Ugurbil K.
Published: July 2002

▪ Abstract  In this review we discuss various recent topics that characterize functional magnetic resonance imaging (fMRI). These topics include a brief description of MRI image acquisition, how to cope with noise or signal fluctuation, the basis of fMRI signal changes, and the relation of MRI signal to neuronal events. Several observations of fMRI that show good correlation to the neurofunction are referred to. Temporal characteristics of fMRI signals and examples of how the feature of real time measurement is utilized are then described. The question of spatial resolution of fMRI, which must be dictated by the vascular structure serving the functional system, is discussed based on various fMRI observations. Finally, the advantage of fMRI mapping is shown in a few examples. Reviewing the vast number of recent fMRI application that have now been reported is beyond the scope of this article.
POPULATION GENOMICS: Genome-Wide Sampling of Insect Populations
Authors: Black IV William C. , Baer Charles F. , Antolin Michael F. , DuTeau Nancy M.
Published: July 2002

▪ Abstract  Modern population genetics underwent a major paradigm shift during the last decade of the 20th century with the discovery that thousands of genes of known function and position in a genome can be analyzed simultaneously in a single individual. The impact of this technology on insect population genetics is potentially profound. Sampling distributions of genetic statistics can now be derived from many individual loci or among many segregating sites within a gene. Inferences regarding random mating, gene flow, effective population sizes, disequilibrium, and relatedness among populations can now be based on patterns of variation at many loci. More importantly, genome-wide sampling enables population geneticists to distinguish effects that act on the whole genome from those that act on individual loci or nucleotides. We introduce the term “population genomics” to describe the process of simultaneous sampling of numerous variable loci within a genome and the inference of locus-specific effects from the sample distributions. The four critical assumptions implicit in the population genomics approach are explained in detail. Studies adopting this paradigm are reviewed, and the steps necessary to complete a population genomics study are outlined.
COMPUTATIONAL FLUID DYNAMICS OF WHOLE-BODY AIRCRAFT
Authors: Agarwal Ramesh
Published: July 2002

▪ Abstract  The current state of the art in computational aerodynamics for whole-body aircraft flowfield simulations is described. Recent advances in geometry modeling, surface and volume grid generation, and flow simulation algorithms have led to accurate flowfield predictions for increasingly complex and realistic configurations. As a result, computational aerodynamics has emerged as a crucial enabling technology for the design and development of flight vehicles. Examples illustrating the current capability for the prediction of transport and fighter aircraft flowfields are presented. Unfortunately, accurate modeling of turbulence remains a major difficulty in the analysis of viscosity-dominated flows. In the future, inverse design methods, multidisciplinary design optimization methods, artificial intelligence technology, and massively parallel computer technology will be incorporated into computational aerodynamics, opening up greater opportunities for improved product design at substantially reduced costs.
History of Plant Population Genetics
Authors: Allard Robert W.
Published: July 2002

▪ Abstract  This review of plant population genetics focuses on the genetic foundations of the processes that have led to documentable improvements in cultivated plants since the earliest domestications took place perhaps 13,000 years ago. Nearly all human civilizations have depended heavily on inbreeding plants (particularly wheat, barley, soybeans and other inbreeding legumes), as well as outbreeding vegetatively propagated species (white potatoes, yams) as their dietary standbys. The principal exception is maize (corn), an annual seed-produced outbreeder in nature. It is noteworthy that maize joined wheat, rice, and barley as a truly major crop worldwide only after its conversion to self-pollination combined with hybridization between favorably interacting inbred lines increased yield of maize several-fold in the twentieth century.
Homologous Recombination Near and Far from DNA Breaks: Alternative Roles and Contrasting Views
Authors: Smith Gerald R.
Published: July 2002

▪ Abstract  Double-strand breaks and other lesions in DNA can stimulate homologous genetic recombination in two quite different ways: by promoting recombination near the break (roughly within a kb) or far from the break. Recent emphasis on the repair aspect of recombination has focused attention on DNA interactions and recombination near breaks. Here I review evidence for recombination far from DNA breaks in bacteria and fungi and discuss mechanisms by which this can occur. These mechanisms include entry of a traveling entity (“recombination machine”) at a break, formation of long heteroduplex DNA, priming of DNA replication by a broken end, and induction of recombination potential in trans. Special emphasis is placed on contrasting views of how the RecBCD enzyme of Escherichia coli promotes recombination far (tens of kb) from a double-strand break. The occurrence of recombination far from DNA breaks and of correlated recombination events far apart suggests that “action at a distance” during recombination is a widespread feature among diverse organisms.
Disseminating the Genome: Joining, Resolving, and Separating Sister Chromatids During Mitosis and Meiosis
Authors: Nasmyth Kim
Published: July 2002

▪ Abstract  The separation of sister chromatids at the metaphase to anaphase transition is one of the most dramatic of all cellular events and is a crucial aspect of all sexual and asexual reproduction. The molecular basis for this process has until recently remained obscure. New research has identified proteins that hold sisters together while they are aligned on the metaphase plate. It has also shed insight into the mechanisms that dissolve sister chromatid cohesion during both mitosis and meiosis. These findings promise to provide insights into defects in chromosome segregation that occur in cancer cells and into the pathological pathways by which aneuploidy arises during meiosis.
TRANSCRIPTIONAL REGULATION DURING B CELL DEVELOPMENT
Authors: Henderson Andrew , Calame Kathryn
Published: July 2002

▪ Abstract  Information is increasingly available concerning the molecular events that occur during primary and antigen-dependent stages of B cell development. In this review the roles of transcription factors and coactivators are discussed with respect to changes in expression patterns of various genes during B cell development. Transcriptional regulation is also discussed in the context of developmentally regulated immunoglobulin gene V(D)J recombination, somatic hypermutation, and isotype switch recombination.
CERAMICS IN RESTORATIVE AND PROSTHETIC DENTISTRY
Authors: Kelly J. Robert
Published: July 2002

▪ Abstract  This review is intended to provide the ceramic engineer with information about the history and current use of ceramics in dentistry, contemporary research topics, and potential research agenda. Background material includes intra-oral design considerations, descriptions of ceramic dental components, and the origin, composition, and microstructure of current dental ceramics. Attention is paid to efforts involving net-shape processing, machining as a forming method, and the analysis of clinical failure. A rationale is presented for the further development of all-ceramic restorative systems. Current research topics receiving attention include microstructure/processing/property relationships, clinical failure mechanisms and in vitro testing, wear damage and wear testing, surface treatments, and microstructural modifications. The status of the field is critically reviewed with an eye toward future work. Significant improvements seem possible in the clinical use of ceramics based on engineering solutions derived from the study of clinically failed restorations, on the incorporation of higher levels of “biomimicry” in new systems, and on the synergistic developments in dental cements and adhesive dentin bonding.
Mitochondrial Disorders: Clinical and Genetic Features
Authors: Simon, MD, PhD D.K. , Johns, MD D.R.
Published: July 2002

Virtually all cells in humans depend on mitochondrial oxidative phosphorylation to generate energy, accounting for the remarkable diversity of clinical disorders associated with mitochondrial DNA mutations. However, certain tissues are particularly susceptible to mitochondrial dysfunction, resulting in recognizable clinical syndromes. Mitochondrial DNA mutations have been linked to seizures, strokes, optic atrophy, neuropathy, myopathy, cardiomyopathy, sensorineural hearing loss, diabetes mellitus, and other clinical features. Mitochondrial DNA mutations also may play an important role in aging, as well as in common age-related neurodegenerative disorders such as Parkinson's disease. Therefore, it is becoming increasingly important for clinicians to recognize the clinical syndromes suggestive of a mitochondrial disorder, and to understand the unique features of mitochondrial genetics that complicate diagnosis and genetic counseling.
Neurocysticercosis: Updates on Epidemiology, Pathogenesis, Diagnosis, and Management
Authors: White A. Clinton
Published: July 2002

▪ Abstract  Neurocysticercosis is now recognized as a common cause of neurologic disease in developing countries and the United States. The pathogenesis and clinical manifestations vary with the site of infection and accompanying host response. Inactive infection should be treated symptomatically. Active parenchymal infection results from an inflammatory reaction to the degenerating cysticercus and will also respond to symptomatic treatment. Controlled trials have not demonstrated a clinical benefit for antiparasitic drugs. Ventricular neurocysticercosis often causes obstructive hydrocephalus. Surgical intervention, especially cerebrospinal fluid diversion, is the key to management of hydrocephalus. Shunt failure may be less frequent when patients are treated with prednisone and/or antiparasitic drugs. Subarachnoid cysticercosis is associated with arachnoiditis. The arachnoiditis may result in meningitis, vasculitis with stroke, or hydrocephalus. Patients should be treated with corticosteroids, antiparasitic drugs, and shunting if hydrocephalus is present.
Heart Transplantation: A Thirty-Year Perspective
Authors: Miniati Douglas N. , Robbins Robert C.
Published: July 2002

▪ Abstract  Heart transplantation has evolved over the past 30 years into a mainstay of therapy for heart failure patients. As the surgical technique and basic immunology were defined, heart transplantation became a real therapeutic option. Over the next few decades, thoracic transplant teams at Stanford University and other institutions refined this mode of therapy. This review addresses the history, current surgical technique, recipient and donor selection, postoperative care, immunosuppression, short- and long-term complications, and clinical outcomes associated with this procedure.
MAKING BRAIN CONNECTIONS: Neuroanatomy and the Work of TPS Powell, 1923–1996
Authors: Jones Edward G.
Published: July 2002

▪ Abstract  Dr. Thomas PS Powell was one of the founders of modern neuroanatomy. His career spanned an era that saw techniques for analyzing connections in the central nervous system dramatically increase in number and resolving power. In tracing the history of his research, one can see how the introduction of each new technique provided an incremental step in analytical capacity although eventually revealing its own limitations. Also evident is the extent to which prejudices born in the days of applying earlier techniques could continue to influence the interpretation of results obtained with new ones. Powell's contributions to neuroscience were extremely wide-ranging, encompassing investigations of the circuitry of the basal ganglia, corticofugal connections, topographic maps in sensory systems, central olfactory pathways, corticocortical and commissural connections, and pathways for sensory convergence in the cerebral cortex. From these investigations, made with tract tracing techniques, much existing knowledge of forebrain organization is derived. He was also one of the earliest investigators to use electron microscopy in the investigation of the central nervous system, and his electron microscopic studies on the olfactory bulb, thalamus, cerebral cortex, and basal ganglia laid, to a large extent, the foundations for all modern research on the synaptic circuitry of these structures. He was given to synthesizing data across systems in order to arrive at common principles of brain organization. A number of these syntheses have been sources of great interest and, occasionally, controversy.
The Koniocellular Pathway in Primate Vision
Authors: Hendry Stewart H. C. , Reid R. Clay
Published: July 2002

A neurochemically distinct population of koniocellular (K) neurons makes up a third functional channel in primate lateral geniculate nucleus. As part of a general pattern, K neurons form robust layers through the full representation of the visual hemifield. Similar in physiology and connectivity to W cells in cat lateral geniculate nucleus, K cells form three pairs of layers in macaques. The middle pair relays input from short-wavelength cones to the cytochrome-oxidase blobs of primay visual cortex (V1), the dorsal-most pair relays low-acuity visual information to layer I of V1, and the ventral-most pair appears closely tied to the function of the superior colliculus. Throughout each K layer are neurons that innervate extrastriate cortex and that are likely to sustain some visual behaviors in the absence of V1. These data show that several pathways exist from retina to V1 that are likely to process different aspects of the visual scene along lines that may remain parallel well into V1.
Confronting Complexity: Strategies for Understanding the Microcircuitry of the Retina
Authors: Masland Richard H. , Raviola Elio
Published: July 2002

The mammalian retina contains upward of 50 distinct functional elements, each carrying out a specific task. Such diversity is not rare in the central nervous system, but the retina is privileged because its physical location, the distinctive morphology of its neurons, the regularity of its architecture, and the accessibility of its inputs and outputs permit a unique variety of experiments. Recent strategies for confronting the retina’s complexity attempt to marry genetic approaches to new kinds of anatomical and electrophysiological techniques.
THE QCD VACUUM AS AN INSTANTON LIQUID
Authors: Shuryak E. , Schäfer T.
Published: July 2002

▪ Abstract  We review recent progress in understanding the importance of instanton effects in QCD. Instantons provide a mechanism for quark and gluon condensation, explain the U(1)A anomaly and the appearance of a non-perturbative vacuum energy density. In the framework of the instanton liquid model, a large number of hadronic correlation functions were calculated. The results are in good agreement with both experimental data and lattice simulations. We also review recent results on the phase structure of QCD-like theories. Instantons provide a mechanism for chiral symmetry restoration at finite temperature (or for a large number of quark flavors) connected with the formation of instanton–anti-instanton molecules.
EVOLUTION AND REGULATION OF UREA SYNTHESIS AND UREOTELY IN (BATRACHOIDID) FISHES
Authors: Walsh Patrick J.
Published: July 2002

▪ Abstract  Selected teleostean (bony) fish species of the family Batrachoididae (toadfishes and midshipmen) possess high titers of all enzymes of the ornithine-urea cycle in their livers. These species have proven valuable in understanding the short-term regulation of urea synthesis, urea permeability, and transport across epithelial tissues, and how urea synthesis and excretion have evolved among vertebrates. One species in particular, the gulf toadfish (Opsanus be), has been shown to rapidly switch from ammonia excretion to urea synthesis and excretion during a variety of stress conditions (including confinement). The transition is accompanied by an upregulation of hepatic glutamine synthetase activity, and a switch to pulsatile urea excretion from the anterior end of the fish. In fact, a single day's excretion can be voided in a period of <3 h. Hypotheses on the environmental significance of these patterns of urea synthesis and excretion are discussed.
HORMONE REPLACEMENT THERAPY, HEART DISEASE, AND OTHER CONSIDERATIONS
Authors: Barrett-Connor Elizabeth , Grady Deborah
Published: July 2002

▪ Abstract  Multiple observational studies suggest a marked reduction in risk of coronary heart disease (CHD) associated with postmenopausal estrogen use. A new meta-analysis presented here extends these results to estrogen plus progestin regimens. Although the findings from observational studies are strong and consistent, and there are several plausible mechanisms by which estrogen might reduce risk for CHD, most of the known biases would tend to exaggerate estrogen's benefit. Further, estrogen therapy clearly increases risk for endometrial hyperplasia and cancer, venous thromboembolic events and gallbladder disease, and long-term use probably also increases the risk of breast cancer. Therefore, until findings from randomized trials confirm and quantitate the benefit of estrogen therapy for prevention of CHD, we believe it should not be recommended to all postmenopausal women.
Color, Form, and Motion: Dimensions of a Musical Art of Light
Authors: Collopy Fred
Published: July 2002

Lumia are an art form that permits visual artists to play images in the way that musicians play with sounds. Though the idea of creating lumia has a long historical tradition, modern graphicallybased computers make it possible to design instruments for creating lumia that are more flexible and easier to play than at any previous time in the history of art. In designing and playing lumia, three principal dimensions require attention: color, form, and motion. By organizing the design of lumia and instruments for creating them along these dimensions, it is possible to learn a great deal from art theory and history, as guidelines have been devised for the effective use of each of these dimensions.
Middles and Reflexivity
Authors: Stroik Thomas
Published: July 2002

This article investigates the argument structure of middle predicates. It argues that middle verbs syntactically project the entire argument grids of their active counterparts; however, middle verbs, like passive verbs, project the external (Agent) arguments of their active counterparts as adjuncts. These demoted Agent arguments can appear, in middle constructions, as the objects of for-PPs.
A Crosslinguistic PET Study of Tone Perception
Authors: Gandour Jack , Wong Donald , Hsieh Li , Weinzapfel Bret , Lancker Diana Van , Hutchins Gary D.
Published: July 2002

In studies of pitch processing, a fundamental question is whether shared neural mechanisms at higher cortical levels are engaged for pitch perception of linguistic and nonlinguistic auditory stimuli. Positron emission tomography (PET) was used in a crosslinguistic study to compare pitch processing in native speakers of two tone languages (that is, languages in which variations in pitch patterns are used to distinguish lexical meaning), Chinese and Thai, with those of English, a nontone language. Five subjects from each language group were scanned under three active tasks (tone, pitch, and consonant) that required focused-attention, speeded-response, auditory discrimination judgments, and one passive baseline as silence. Subjects were instructed to judge pitch patterns of Thai lexical tones in the tone condition; pitch patterns of nonspeech stimuli in the pitch condition; syllable-initial consonants in the consonant condition. Analysis was carried out by paired-image subtraction. When comparing the tone to the pitch task, only the Thai group showed significant activation in the left frontal operculum. Activation of the left frontal operculum in the Thai group suggests that phonological processing of suprasegmental as well as segmental units occurs in the vicinity of Broca's area. Baseline subtractions showed significant activation in the anterior insular region for the English and Chinese groups, but not Thai, providing further support for the existence of possibly two parallel, separate pathways projecting from the temporo-parietal to the frontal language area. More generally, these differential patterns of brain activation across language groups and tasks support the view that pitch patterns are processed at higher cortical levels in a top-down manner according to their linguistic function in a particular language.
Impaired Processing of Complex Auditory Stimuli in Rats with Induced Cerebrocortical Microgyria: An Animal Model of Developmental Language Disabilities
Authors: Clark Matthew G. , Rosen Glenn D. , Tallal Paula , Fitch R. Holly
Published: July 2002

Individuals with developmental language disabilities, including developmental dyslexia and specific language impairment (SLI), exhibit impairments in processing rapidly presented auditory stimuli. It has been hypothesized that these deficits are associated with concurrent deficits in speech perception and, in turn, impaired language development. Additionally, postmortem analyses of human dyslexic brains have revealed the presence of focal neocortical malformations such as cerebrocortical microgyria. In an initial study bridging these research domains, we found that male rats with induced microgyria were impaired in discriminating rapidly presented auditory stimuli. In order to further assess this anatomical-behavioral association, we designed two experiments using auditory-reflex modification. These studies were intended to assess whether auditory processing deficits in microgyric male rats would be seen in threshold detection of a silent gap in white noise, and in oddball detection of a two-tone stimulus of variable duration. Results showed no differences between sham and microgyric subjects on gap detection, but did show that microgyric subjects were impaired in the discrimination of two-tone stimuli presented in an oddball paradigm. This impairment was evident for stimuli with total duration of 64 msec or less, while both groups were able to discriminate stimuli with duration of 89 msec or greater. The current results further support the relationship between malformations of the cerebral cortex and deficits in rapid auditory processing. They also suggest that the parameters characterizing rapid auditory processing deficits for a specific task may be influenced by stimulus features and/or cognitive demand of that particular task.
Encoding of Categories by Noncategory-Specific Neurons in the Inferior Temporal Cortex
Authors: Thomas Elizabeth , Van Hulle Marc M. , Vogel Rufin
Published: July 2002

In order to understand how the brain codes natural categories, e.g., trees and fish, recordings were made in the anterior part of the macaque inferior temporal (IT) cortex while the animal was performing a tree/nontree categorization task. Most single cells responded to exemplars of more than one category while other neurons responded only to a restricted set of exemplars of a given category. Since it is still not known which type of cells contribute and what is the nature of the code used for categorization in IT, we have performed an analysis on single-cell data. A Kohonen self-organizing map (SOM), which uses an unsupervised (competitive) learning algorithm, was used to study the single cell responses to tree and nontree images. Results from the Kohonen SOM indicated that the collected neuronal data consisting of spike counts was sufficient to account for a good level of categorization success (approximately 83%) when categorizing a group of 200 trees and nontrees. Contrary to intuition, the results of the investigation suggest that the population of category-specific neurons (neurons that respond only to trees or only to nontrees) was unimportant to the categorization. Instead, a large majority of the neurons that were most important to the categorization was found to belong to a class of more broadly tuned cells, namely, cells that responded to both categories but that favored one category over the other by seven or more images. A simple algebraic operation (without the Kohonen SOM) between the above-mentioned noncategory-specific neurons confirmed the contribution of these neurons to categorization. Thus, the modeling results suggest (1) that broadly tuned neurons are critical for categorization, and (2) that only one additional layer of processing is required to extract the categories from a population of IT neurons.
When Keeping in Mind Supports Later Bringing to Mind: Neural Markers of Phonological Rehearsal Predict Subsequent Remembering
Authors: Davachi Lila , Maril Anat , Wagner Anthony D.
Published: July 2002

The ability to bring to mind a past experience depends on the cognitive and neural processes that are engaged during the experience and that support memory formation. A central and much debated question is whether the processes that underlie rote verbal rehearsal—that is, working memory mechanisms that keep information in mind—impact memory formation and subsequent remembering. The present study used event-related functional magnetic resonance imaging (fMRI) to explore the relation between working memory maintenance operations and long-term memory. Specifically, we investigated whether the magnitude of activation in neural regions supporting the on-line maintenance of verbal codes is predictive of subsequent memory for words that were rote-rehearsed during learning. Furthermore, during rote rehearsal, the extent of neural activation in regions associated with semantic retrieval was assessed to determine the role that incidental semantic elaboration may play in subsequent memory for rote-rehearsed items. Results revealed that (a) the magnitude of activation in neural regions previously associated with phonological rehearsal (left prefrontal, bilateral parietal, supplementary motor, and cerebellar regions) was correlated with subsequent memory, and (b) while rote rehearsal did not—on average—elicit activation in an anterior left prefrontal region associated with semantic retrieval, activation in this region was greater for trials that were subsequently better remembered. Contrary to the prevalent view that rote rehearsal does not impact learning, these data suggest that phonological maintenance mechanisms, in addition to semantic elaboration, support the encoding of an experience such that it can be later remembered.
Event-Related Brain Potentials and Case Information in Syntactic Ambiguities
Authors: Hopf Jens-Max , Bayer Josef , Bader Markus , Meng Michael
Published: July 2002

In an ERP study, German sentences were investigated that contain a case-ambiguous NP that may be assigned accusative or dative case. Sentences were disambiguated by the verb in final position of the sentence. As our data show, sentences ending in a verb that assigns dative case to the ambiguous NP elicit a clear garden-path effect. The garden-path effect was indicated by a broad centro-posterior negative shift that occurred between 300 and 900 msec after the dative-assigning verb was presented. No enhanced P600 following the misanalysis was observed. Noun phrases whose case ambiguity was resolved in favor of accusative case and unambiguously dative-marked NPs did not trigger significant ERP differences. We will discuss the implications of our results for parsing and its neuropsychological correlates. The results of this study support a parser design according to which the so-called structural case (nominative or accusative) is assigned without any delay in the absence of morpho-lexical counterevidence. It is argued that the enhancement of a negative ERP component with a ficlassicalfl N400 topography refiects the difficulty of reanalysis due to reaccessing morpho-lexical information that lies outside the domain of the parsing module. Consequently, ERP responses to garden-path effects are not confined to a late positivity but vary depending on the level of processing involved in reanalysis. The fact that garden-path effects may also elicit an N400 can be linked to the nonhomogeneous linguistic properties of the constructions from which they arise.
Detecting and Estimating Signals over Noisy and Unreliable Synapses: Information-Theoretic Analysis
Authors: Manwani Amit , Koch Christof
Published: July 2002

The temporal precision with which neurons respond to synaptic inputs has a direct bearing on the nature of the neural code. A characterization of the neuronal noise sources associated with different sub-cellular components (synapse, dendrite, soma, axon, and so on) is needed to understand the relationship between noise and information transfer. Here we study the effect of the unreliable, probabilistic nature of synaptic transmission on information transfer in the absence of interaction among presynaptic inputs. We derive theoretical lower bounds on the capacity of a simple model of a cortical synapse under two different paradigms. In signal estimation, the signal is assumed to be encoded in the mean firing rate of the presynaptic neuron, and the objective is to estimate the continuous input signal from the postsynaptic voltage. In signal detection, the input is binary, and the presence or absence of a presynaptic action potential is to be detected from the postsynaptic voltage. The efficacy of information transfer in synaptic transmission is characterized by deriving optimal strategies under these two paradigms. On the basis of parameter values derived from neocortex, we find that single cortical synapses cannot transmit information reliably, but redundancy obtained using a small number of multiple synapses leads to a significant improvement in the information capacity of synaptic transmission.
Extracting Oscillations: Neuronal Coincidence Detection with Noisy Periodic Spike Input
Authors: Kempter Richard , Gerstner Wulfram , Hemmen J. Leo van , Wagner Hermann
Published: July 2002

How does a neuron vary its mean output firing rate if the input changes from random to oscillatory coherent but noisy activity? What are the critical parameters of the neuronal dynamics and input statistics? To answer these questions, we investigate the coincidence-detection properties of an integrate-and-fire neuron. We derive an expression indicating how coincidence detection depends on neuronal parameters. Specifically, we show how coincidence detection depends on the shape of the postsynaptic response function, the number of synapses, and the input statistics, and we demonstrate that there is an optimal threshold. Our considerations can be used to predict from neuronal parameters whether and to what extent a neuron can act as a coincidence detector and thus can convert a temporal code into a rate code.
A Systematic and Effective Supervised Learning Mechanism Based on Jacobian Rank Deficiency
Authors: Zhou Guian , Si Jennie
Published: July 2002

Most neural network applications rely on the fundamental approximation property of feedforward networks. Supervised learning is a means of implementing this approximate mapping. In a realistic problem setting, a mechanism is needed to devise this learning process based on available data, which encompasses choosing an appropriate set of parameters in order to avoid overfitting, using an efficient learning algorithm measured by computation and memory complexities, ensuring the accuracy of the training procedure as measured by the training error, and testing and cross-validation for generalization.

We develop a comprehensive supervised learning algorithm to address these issues. The algorithm combines training and pruning into one procedure by utilizing a common observation of Jacobian rank deficiency in feedforward networks. The algorithm not only reduces the training time and overall complexity but also achieves training accuracy and generalization capabilities comparable to more standard approaches. Extensive simulation results are provided to demonstrate the effectiveness of the algorithm.
Near-Saddle-Node Bifurcation Behavior as Dynamics in Working Memory for Goal-Directed Behavior
Authors: Nakahara* Hiroyuki , Doya Kenji
Published: July 2002

In consideration of working memory as a means for goal-directed behavior in nonstationary environments, we argue that the dynamics of working memory should satisfy two opposing demands: long-term maintenance and quick transition. These two characteristics are contradictory within the linear domain. We propose the near-saddle-node bifurcation behavior of a sigmoidal unit with a self-connection as a candidate of the dynamical mechanism that satisfies both of these demands. It is shown in evolutionary programming experiments that the near-saddle-node bifurcation behavior can be found in recurrent networks optimized for a task that requires efficient use of working memory. The result suggests that the near-saddle-node bifurcation behavior may be a functional necessity for survival in nonstationary environments.
Firing Rate Distributions and Efficiency of Information Transmission of Inferior Temporal Cortex Neurons to Natural Visual Stimuli
Authors: Treves Alessandro , Panzeri Stefano , Rolls Edmund T. , Booth Michael , Wakeman Edward A.
Published: July 2002

The distribution of responses of sensory neurons to ecological stimulation has been proposed to be designed to maximize information transmission, which according to a simple model would imply an exponential distribution of spike counts in a given time window. We have used recordings from inferior temporal cortex neurons responding to quasi-natural visual stimulation (presented using a video of everyday lab scenes and a large number of static images of faces and natural scenes) to assess the validity of this exponential model and to develop an alternative simple model of spike count distributions. We find that the exponential model has to be rejected in 84% of cases (at the p < 0.01 level). A new model, which accounts for the firing rate distribution found in terms of slow and fast variability in the inputs that produce neuronal activation, is rejected statistically in only 16% of cases. Finally, we show that the neurons are moderately efficient at transmitting information but not optimally efficient.
Music, Language and Environment
Authors: Dunn David , van Peer René
Published: July 2002

Interviewed by music journalist René van Peer, the composer and sound recordist David Dunn discusses the sound work he has done in natural environments, his motivations for doing this work, and the thoughts and theories he has developed from it. Most of these works are unique events created for a specific time and location or for specific circumstances. In these events, the sounds generated by the players set up interactions with their immediate surroundings. Soundscape recordings are another aspect of Dunn's work. His work in different natural and cultural environments has enabled him to research areas where music and language intersect.
The Sounds of Physical Shapes
Authors: Doel Kees van den , Pai Dinesh K.
Published: July 2002

We propose a general framework for the simulation of sounds produced by colliding physical objects in a virtual reality environment. The framework is based on the vibration dynamics of bodies. The computed sounds depend on the material of the body, its shape, and the location of the contact.

This simulation of sounds allows the user to obtain important auditory clues about the objects in the simulation, as well as about the locations on the objects of the collisions.

Specifically, we show how to compute (1) the spectral signature of each body (its natural frequencies), which depends on the material and the shape, (2) the “timbre” of the vibration (the relative amplitudes of the spectral components) generated by an impulsive force applied to the object at a grid of locations, (3) the decay rates of the various frequency components that correlate with the type of material, based on its internal friction parameter, and finally (4) the mapping of sounds onto the object's geometry for real-time rendering of the resulting sound.

The framework has been implemented in a Sonic Explorer program which simulates a room with several objects such as a chair, tables, and rods. After a preprocessing stage, the user can hit the objects at different points to interactively produce realistic sounds.