bluuebunny/crossref_metadata_2025 huggingface dataset:
Two mesocosm experiments investigating the control of summer phytoplankton growth in a small shallow lake
Authors: Stephen D. , Balayla D. M. , Collings S. E. , Moss Brian
Published: November 2004

1. Mesocosm experiments were carried out to examine the relative importance of top down (fish predation) and bottom up (nutrient addition) controls on phytoplankton abundance in a small shallow lake, Little Mere, U.K., in 1998 and 1999. These experiments were part of a series at six sites across Europe.

2. In the 1998 experiment, top‐down processes (through grazing of large Cladocera) were important in determining phytoplankton biomass. The lack of plant refugia for zooplankton was probably important in causing an increasing chlorophyll a concentration even at intermediate fish density. Little Mere normally has abundant macrophytes but they failed to develop substantially during both years. Bottom‐up control was not important in 1998, most probably because of high background nutrient concentrations, as a result of nutrient release from the sediments.

3. In 1999 neither top‐down nor bottom‐up processes were significant in determining phytoplankton biomass. Large cladoceran grazers were absent even in the fish‐free enclosures, probably because dominance of cyanobacteria and high phytoplankton biomass made feeding conditions unsuitable. As in 1998, bottom‐up control of phytoplankton was not important, owing to background nutrient concentrations that were even higher in 1999 than in 1998, perhaps because of the warmer, sunnier weather.

4. The differing outcomes of the two experiments in the same lake with similar experimental designs highlight the importance of starting conditions. These conditions in turn depended on overall weather conditions prior to the experiments.
The World on the Box: International Issues in News and Factual Programmes
Authors: FRANKS SUZANNE
Published: November 2004

A report on factual international programmes shown on UK TV in 2003 reveals that the total of hours broadcast is similar that of previous years. However, there has been a drop in the number of programmes on developing countries, and the definition of 'factual international' covers a misleadingly wide range ‐ including game shows and travel programmes. The amount of developing country coverage on terrestrial TV is the lowest since the measurement began in 1989. Many serious programmes on developing countries are now shown exclusively on the new BBC digital channels. It appears that ITV is no longer fulfilling its public service remit to broadcast programmes covering 'matters of international significance and interest'. The proportion of foreign coverage in television news increased in 2003 across all bulletins, as a result of the Iraq war.
Characterization of the Nuclear Deformation Caused by Changes in Endothelial Cell Shape
Authors: Jean Ronald P. , Gray Darren S. , Spector Alexander A. , Chen Christopher S.
Published: November 2004

We investigated the mechanotransduction pathway in endothelial cells between their nucleus and adhesions to the extracellular matrix. First, we measured nuclear deformations in response to alterations of cell shape as cells detach from a flat surface. We found that the nuclear deformation appeared to be in direct and immediate response to alterations of the cell adhesion area. The nucleus was then treated as a neo-Hookean compressible material, and we estimated the stress associated with the cytoskeleton and acting on the nucleus during cell rounding. With the obtained stress field, we estimated the magnitude of the forces deforming the nucleus. Considering the initial and final components of this adhesion-cytoskeleton-nucleus force transmission pathway, we found our estimate for the internal forces acting on the nucleus to be on the same order of magnitude as previously measured traction forces, suggesting a direct mechanical link between adhesions and the nucleus.
Evolutionary and Functional Relationships of Colonization Factor Antigen I and Other Class 5 Adhesive Fimbriae of Enterotoxigenic
Escherichia coli
Authors: Anantha Ravi P. , McVeigh Annette L. , Lee Lanfong H. , Agnew Mary K. , Cassels Frederick J. , Scott Daniel A. , Whittam Thomas S. , Savarino Stephen J.
Published: November 2004

Colonization factor antigen I (CFA/I) is the archetype of eight genetically related fimbriae of enterotoxigenic
Escherichia coli
(ETEC) designated class 5 fimbriae. Assembled by the alternate chaperone pathway, these organelles comprise a rigid stalk of polymerized major subunits and an apparently tip-localized minor adhesive subunit. We examined the evolutionary relationships of class 5-specific structural proteins and correlated these with functional properties. We sequenced the gene clusters encoding coli surface antigen 4 (CS4), CS14, CS17, CS19, and putative colonization factor antigen O71 (PCFO71) and analyzed the deduced proteins and the published homologs of CFA/I, CS1, and CS2. Multiple alignment and phylogenetic analysis of the proteins encoded by each operon define three subclasses, 5a (CFA/I, CS4, and CS14), 5b (CS1, CS17, CS19, and PCFO71), and 5c (CS2). These share distant evolutionary relatedness to fimbrial systems of three other genera. Subclass divisions generally correlate with distinguishing in vitro adherence phenotypes of strains bearing the ETEC fimbriae. Phylogenetic comparisons of the individual structural proteins demonstrated greater intrasubclass conservation among the minor subunits than the major subunits. To correlate this with functional attributes, we made antibodies against CFA/I and CS17 whole fimbriae and maltose-binding protein fusions with the amino-terminal half of the corresponding minor subunits. Anti-minor subunit Fab preparations showed hemagglutination inhibition (HAI) of ETEC expressing homologous and intrasubclass heterologous colonization factors while anti-fimbrial Fab fractions showed HAI activity limited to colonization factor-homologous ETEC. These results were corroborated with similar results from the Caco-2 cell adherence assay. Our findings suggest that the minor subunits of class 5 fimbriae may be superior to whole fimbriae in inducing antiadhesive immunity.
Development of a System To Study CD4+-T-Cell Responses to Transgenic Ovalbumin-ExpressingToxoplasma gondiiduring Toxoplasmosis
Authors: Pepper Marion , Dzierszinski Florence , Crawford Amy , Hunter Christopher A. , Roos David
Published: November 2004

The study of the immune response toToxoplasma gondiihas provided numerous insights into the role of T cells in resistance to intracellular infections. However, the complexity of this eukaryote pathogen has made it difficult to characterize immunodominant epitopes that would allow the identification of T cells with a known specificity for parasite antigens. As a consequence, analysis of T-cell responses toT. gondiihas been based on characterization of the percentage of T cells that express an activated phenotype during infection and on the ability of these cells to produce cytokines in response to complex mixtures of parasite antigens. In order to study specific CD4+T cells responses toT. gondii, recombinant parasites that express a truncated ovalbumin (OVA) protein, in either a cytosolic or a secreted form, were engineered. In vitro and in vivo studies reveal that transgenic parasites expressing secreted OVA are able to stimulate T-cell receptor-transgenic OVA-specific CD4+T cells to proliferate, express an activated phenotype, and produce gamma interferon (IFN-γ). Furthermore, the adoptive transfer of OVA-specific T cells into IFN-γ−/−mice provided enhanced protection against infection with the OVA-transgenic (but not parental) parasites. Together, these studies establish the utility of this transgenic system to study CD4+-T-cell responses during toxoplasmosis.
Anaplasma marginale
Major Surface Protein 2 CD4
+
-T-Cell Epitopes Are Evenly Distributed in Conserved and Hypervariable Regions (HVR), Whereas Linear B-Cell Epitopes Are Predominantly Located in the HVR
Authors: Abbott Jeffrey R. , Palmer Guy H. , Howard Chris J. , Hope Jayne C. , Brown Wendy C.
Published: November 2004

Organisms in the genus
Anaplasma
express an immunodominant major surface protein 2 (MSP2), composed of a central hypervariable region (HVR) flanked by highly conserved regions. Throughout
Anaplasma marginale
infection, recombination results in the sequential appearance of novel MSP2 variants and subsequent control of rickettsemia by the immune response, leading to persistent infection. To determine whether immune evasion and selection for variant organisms is associated with a predominant response against HVR epitopes, T-cell and linear B-cell epitopes were localized by measuring peripheral blood gamma interferon-secreting cells, proliferation, and antibody binding to 27 overlapping peptides spanning MSP2 in 16 cattle. Similar numbers of MSP2-specific CD4
+
T-cell epitopes eliciting responses of similar magnitude were found in conserved and hypervariable regions. T-cell epitope clusters recognized by the majority of animals were identified in the HVR (amino acids [aa] 171 to 229) and conserved regions (aa 101 to 170 and 272 to 361). In contrast, linear B-cell epitopes were concentrated in the HVR, residing within hydrophilic sequences. The pattern of recognition of epitope clusters by T cells and of HVR epitopes by B cells is consistent with the influence of protein structure on epitope recognition.
Variability in milk fatty acids: recreating a foraging trip to test dietary predictions in Antarctic fur seals
Authors: Staniland Iain J , Pond David
Published: November 2004

Using Antarctic fur seals (Arctocephalus gazella (Peters, 1875)) in a feeding trial, we investigated the use of milk fatty acids to determine diet. In a regime designed to replicate an average foraging trip, six female seals were fed on four successive days meals of krill (Euphausia superba Dana, 1850; day 1), mixed krill and icefish (Champsocephalus gunnari Lönnberg, 1905; day 2), and icefish (days 3 and 4). Four milk samples were collected from each female, one every 12 h from the time of the last feed. Fatty acid profiles of samples were analysed using canonical discriminant analysis and classification trees. Milk fatty acids could be used to distinguish between seals fed the experimental diet, which was high in fish, and those feeding naturally, thought to be consuming mostly krill. However, there was significant variation between individual seals, which may have been the influence of feeding prior to the experiment. Milk fatty acids remained relatively unchanged over time, suggesting that the influence of dietary fatty acids was averaged over the suckling period. We conclude that, whilst this technique has potential in studying the diet of higher predators, further work is needed to test the underlying assumptions and mechanisms involved in the transfer of fatty acids from the diet into milk.
SEARCHING A PSEUDO 3-SIDED SOLID ORTHOCONVEX GRID
Authors: SYMVONIS ANTONIOS , TRAGOUDAS SPYROS
Published: November 2004

In this paper we examine the edge searching problem on pseudo 3-sided solid orthoconvex grids. We define a similar problem which we call modified edge searching, and we derive a relation among the original edge searching problem and the modified one. Then, for the modified edge searching problem, we show that there are searching strategies that possess several properties regarding the way the grid is searched. These strategies allow us to obtain a closed formula that expresses the minimum number of searchers required to search a pseudo 3-sided solid orthoconvex grid. From that formula and a rather straight forward algorithm we can show that the problem is in P. We obtain a parallel version of that algorithm that places the problem in NC. For the case of sequential algorithms, we derive an optimal algorithm that solves the problem in O (m) time where m is the number of points necessary to describe the orthoconvex grid. Another important feature of our method is that it also suggests an optimal searching strategy that consists of O (n) steps, where n is the number of nodes of the grid.
PRACTICAL PROBLEMS USING NEURAL NETWORKS
Authors: Soulie Françoise Fogelman
Published: November 2004

Neural Networks are very efficient for real world applications. However, practical problems often arise which can hinder performances. We discuss here some of these problems: under-representation of classes, rejection of outliers and ambiguous patterns, and illustrate the issues raised through various applications.
DRIFT CHAMBER TRACKING WITH A VLSI NEURAL NETWORK
Authors: Lindsey Clark S. , Denby Bruce , Haggerty Herman , Johns Ken
Published: November 2004

We have tested a commercial analog VLSI neural network chip for finding in real time the intercept and slope of charged particles traversing a drift chamber. Voltages proportional to the drift times were input to the Intel ETANN chip and the outputs were recorded and later compared off line to conventional track fits. We will discuss the chamber and test setup, the chip specifications, and results of recent tests. We’ll briefly discuss possible applications in high energy physics detector triggers.
CHARACTERISTIC FEATURES OF Kβ X-RAYS DEPENDING ON SODIUM CONTENTS IN Na2O-SiO2 GLASSES
Authors: Iihara J. , Kawai J. , Sekine T. , Yoshihara K.
Published: November 2004

Si K x-ray spectra in SiO 2- Na 2 O were measured with a double-crystal spectrometer. Remarkable change of peak energy, FWHM and intensity were found, depending on sodium contents. Theoretical spectra of Si K β x-ray were calculated to explain the change of x-ray intensity.
THERMODYNAMIC PROPERTIES OF HIGH TEMPERATURE ALLOYS: A METALLURGICAL APPLICATION OF THE PIXE TECHNIQUE
Authors: CAPOBIANCO CHRISTOPHER J. , ROGERS PAMELA S.Z.
Published: November 2004

A simple method for determining thermodynamic mixing parameters for alloys is described. The method takes advantage of small solubilities of alloy components in a high-temperature molten silicate solvent and utilizes the trace element analytical capabilities of the PIXE technique. PIXE analyses were obtained on glasses for a series of (Au, Pd) alloys which had been equilibrated with a fixed composition silicate melt at 1450 °C. Concentrations of Au and Pd in glass obtained from high-temperature experiments record a quantity directly proportional to the vapor pressure of the alloy components when the concentrations are low enough to have constant activity coefficients in the melt. Small negative deviations from ideal mixing were found in liquid and solid solutions for the (Au, Pd) binary. The ability to make good precision analyses at low concentrations, essential to the method, is enabled by PIXE. The advantage of the method lies in its simplicity and because mixing properties may be investigated for experimental conditions where other methods are difficult to implement.
ANALOGUE SIGNAL PROCESSING: THE “CURRENT” WAY OF THINKING
Authors: TOUMAZOU CHRISTOFER
Published: November 2004

This paper presents a tutorial review of the current-mode approach to analogue electronic circuit design, in particular some of the author’s own research over the past decade covering the development of a new generation of technology specific current-mode analogue signal processing. In this paper various technologies are represented with key current-mode building blocks ranging from current-conveyors, current-feedback operational amplifiers, linear transconductance amplifiers to applications ranging from current-mode active filters to low-noise current-mode optical preamplifiers. Advantages, future trends and perspectives of the current-mode approach are highlighted throughout the paper. The theoretical basis for many of the examples dates back many years but it is only recently due to advances in process technology that many of these techniques have now become a practical reality.
ON THE SYNTHESIS OF MASSIVELY PARALLEL ARCHITECTURES
Authors: THIELE LOTHAR , ARZT ULRICH
Published: November 2004

We describe synthesis methods for massively parallel architectures. In particular, a methodology is proposed which leads to a mechanical and provably correct design of systems consisting of memory banks, switches, and processor arrays. In particular, the trajectory is based on the concept of piecewise-linear/regular algorithms and processor arrays. Complex design transformations such as partitioning, clustering, control generation, and flattening/creation of hierarchical levels are embedded in a homogeneous design flow. The final specification of the implementation not only contains the processing elements but also control flow, control processors and interfaces to memory banks and switches.
LARGE-SCALE SIMULATIONS IN CONDENSED MATTER PHYSICS —THE NEED FOR A TERAFLOP COMPUTER
Authors: BINDER K.
Published: November 2004

The introduction of vector processors {“supercomputers” with a performance in the range of 109 floating point operations (1 GFLOP) per second} has had an enormous impact on computational condensed matter physics. The possibility of a substantially enhanced performance by massively parallel processors (“teraflop” machines with 1012 floating point operations per second) will allow satisfactory treatment of a large range of important scientific problems which have to a great extent thus far escaped numerical resolution. The present paper describes only a few examples (out of a long list of interesting research problems!) for which the availability of “teraflops” will allow spectacular progress, i.e., the modelling of dense macromolecular systems and metallic alloys by molecular dynamics and Monte Carlo simulations.
STEADY, SIMULTANEOUS QUANTUM COMPUTATION: A PARADIGM FOR THE INVESTIGATION OF NONDETERMINISTIC AND NON-RECURSIVE COMPUTATION
Authors: CASTAGNOLI GIUSEPPE , RASETTI MARIO , VINCENZI ANTONIO
Published: November 2004

We introduce the notion of a class of abstract digital computers based on quantum reversibility and indeterminism (not 011 the classical sequential architecture), which are compatible with quantum laws and may perform nondeterministic and non-recursive computation.
MASSIVELY DATA-PARALLEL MOLECULAR DYNAMICS
Authors: BONOMI ERNESTO , TOMASSINI MARCO
Published: November 2004

In light of present day data-parallel computers, an appraisal of molecular dynamics simulations of large N-particle systems, isolated or in contact with a heat-bath, is given. Special attention is focused 011 the Connection Machine CM-2. Particularly the cases of long-range potentials and impulsive hard-core interactions are discussed in detail. Data-parallel strategies including data distribution, communications and computation are presented and compared with well-known sequential approaches. The conclusion offered is that the methods described here are easy to design and offer the possibility of reasonably fast implementations for the reliable simulation of macroscopic samples of matter.
LOCALIZATION VERSUS DAMAGE SPREADING IN IMMUNOLOGICAL SHAPE SPACE: A VECTORIZED ALGORITHM
Authors: STAUFFER DIETRICH
Published: November 2004

The model of de Boer, Segel and Perelson, where the various shapes of antibodies are represented by sites on a d-dimensional lattice and where the antibody concentrations change with time only by constant factors, is simulated in one to ten dimensions, with millions of sites. The algorithm is fully vectorized in spite of the many if-conditions which allow one program to deal with all dimensions d. We find that an initially localized perturbation may spread over the whole lattice in high dimensions but prefers to remain localized in low dimensions.
3-D SPIN GLASSES AND ISING MODELS NEW METHODS ON NEW ARCHITECTURES
Authors: BHANOT GYAN
Published: November 2004

I describe work on 3-d Spin Glasses and the 3-d Ising Model done in collaboration with Michael Creutz at BNL and Jan Lacki at IAS Princeton. We have developed novel techniques to study these systems that make use of parallel architectures. For 3-d spin glasses, our results give strong indication that there is no phase transition in the thermodynamic limit whereas for the Ising model, we are able to extend the weak coupling expansion of the average free energy to 50 excited bonds.
PHYSICS OF FLUCTUATING MEMBRANES
Authors: MAGGS ANTHONY C. , DROUFFE JEAN–MICHEL , LEIBLER STANISLAS
Published: November 2004

The statistical mechanics of fluctuating surfaces has applications in many areas of physics, in particular in the description of phase behavior of amphiphilic molecules. We discuss here some of the approaches which have been made towards this problem.
AN APPLICATION OF A CLUSTER MONTE CARLO METHOD TO THE HEISENBERG MODEL
Authors: CHICCOLI CESARE , PASINI PAOLO , SEMERIA FRANCO , ZANNONI CLAUDIO
Published: November 2004

A Monte Carlo method with boundary conditions of a self-consistent maximum entropy type has been applied to the classical Heisenberg model.
PARALLELIZATION OF THE ISING SIMULATION
Authors: ITO NOBUYASU
Published: November 2004

The parallelization aspect of the Ising Monte Carlo simulation is discussed. It is shown that most of the theoretically interesting simulations now are suitable for the trivial parallelization, that is, the Ising simulation is ideally parallelizable. Furthermore, presently most efficient simulation algorithm for single processor is also a kind of trivial paralellization. Results on the non-equilibrium critical relaxation study is included as an example.
LARGE SCALE SIMULATIONS OF THE KINETIC ISING MODEL
Authors: MÜNKEL CHRISTIAN
Published: November 2004

We present Monte Carlo simulation results for the dynamical critical exponent z of the two- and three-dimensional kinetic Ising model. The z-values were calculated from the magnetization relaxation from an ordered state into the equilibrium state at Tc for very large systems with up to (169984)2 and (3072)3 spins. To our knowledge, these are the largest Ising-systems simulated todate. We also report the successful simulation of very large lattices on a massively parallel MIMD computer with high speedups of approximately 1000 and an efficiency of about 0.93.
OPTIMAL SUBCUBE ASSIGNMENT FOR PARTITIONABLE HYPERCUBES
Authors: KRISHNAMURTI RAMESH , NARAHARI BHAGIRATH
Published: November 2004

This paper formulates and discusses a processor assignment problem arising in partitionable parallel architectures. A partitionable hypercube multiprocessor can simultaneously execute multiple tasks where each task is independently executed on a subcube. Given a p processor hypercube and n independent tasks, where a task can be assigned a subcube of any size, an assignment determines the size of the subcube — i.e., the number of processors — to be assigned to each task. The objective of our problem is to find the optimal assignment which minimizes the maximum execution time among all tasks. We present an O(n log p max { log log p, log n}) algorithm that determines an optimal assignment. This algorithm can be efficiently parallelized, on the p processor hypercube, to obtain an O((n/p) log p log 2(n log p)) parallel assignment algorithm.
A SELF-STABILIZING DISTRIBUTED ALGORITHM TO CONSTRUCT BFS SPANNING TREES OF A SYMMETRIC GRAPH
Authors: SUR SUMIT , SRIMANI PRADIP K.
Published: November 2004

We propose a simple and efficient self-stabilizing distributed algorithm to construct the breadth first search (BFS) spanning tree of an arbitrary connected symmetric graph. We develop a completely new direct approach of graph theoretical reasoning to prove the correctness of our algorithm. The approach seems to have potential to have applications in proving correctness of other self-stabilizing algorithms for graph theoretical problems.
COMPUTATION LIST EVALUATION AND ITS APPLICATIONS
Authors: ALBACEA ELIEZER A.
Published: November 2004

In this paper, we present an algorithm for a generalization of list ranking called computation list evaluation. As a consequence of the generalization and the existence of this algorithm for computation list evaluation, we obtain a generalization of Euler Tour technique. Finally, we present several applications of the generalized Euler Tour technique. Of interest in the applications is the identification of a set of problem instances that are solvable using tree contraction and which can alternatively be solved using a simple algorithm based on the generalized Euler Tour technique.
EMBEDDING MESHES OF d-ARY TREES INTO DE BRUIJN GRAPHS
Authors: BARTH D.
Published: November 2004

We present an embedding of the mesh of d-ary trees, a graph we introduce here, into de Bruijn graphs, which are good topologies for parallel architectures, with an optimal expansion and constant dilation and congestion. We show how to embed several disjoint meshes of d-ary trees in the same de Bruijn graph. It gives some results about emulation of the meshes of d-ary trees by the de Bruijn network.
AN EFFICIENT PROCESSOR ALLOCATION FOR NESTED PARALLEL LOOPS ON DISTRIBUTED MEMORY HYPERCUBES
Authors: PLATA OSCAR , PENA TOMAS F. , RIVERA FRANCISCO F. , ZAPATA EMILIO L.
Published: November 2004

We consider the static processor allocation problem for arbitrarily nested parallel loops on distributed memory, message-passing hypercubes. We present HYPAL (HYpercube Partitioning ALgorithm) as an efficient algorithm to solve this problem. HYPAL calculates an optimal set of partitions of the dimension of the hypercube, and assigns them to the set of iterations of the nested loop. Some considerations about the influence of the communication overhead in order to get a more realistic approach are considered. The main problem at this point is to obtain the communication pattern associated to the parallel program because it depends on scheduling and data distribution.
A GENERAL SCHEME FOR THE EFFECTIVE-MASS SCHRÖDINGER EQUATION AND THE GENERATION OF THE ASSOCIATED POTENTIALS
Authors: BAGCHI B. , GORAIN P. , QUESNE C. , ROYCHOUDHURY R.
Published: November 2004

A systematic procedure to study one-dimensional Schrödinger equation with a position-dependent effective mass (PDEM) in the kinetic energy operator is explored. The conventional free-particle problem reveals a new and interesting situation in that, in the presence of a mass background, formation of bound states is signalled. We also discuss coordinate-transformed, constant-mass Schrödinger equation, its matching with the PDEM form and the consequent decoupling of the ambiguity parameters. This provides a unified approach to many exact results known in the literature, as well as to a lot of new ones.
SUPERSYMMETRY AND THE FOUR-DIMENSIONAL COUNTERPART OF DIMENSIONAL REGULARIZATION
Authors: NOVOTNÝ J.
Published: November 2004

A supersymmetric generalization of the natural four-dimensional counterpart of canonical dimensional regularization developed recently is discussed for SUSY QED. The gauge invariance of the regularization scheme is proved and the method illustrated by simple examples of explicit calculation of one-loop supergraphs. The relation to the regularization by dimensional reduction is briefly discussed.
HIGGS BOSON LOW-ENERGY THEOREMS AND THEIR APPLICATIONS
Authors: DAWSON SALLY , HABER HOWARD E.
Published: November 2004

We examine the Higgs boson low-energy theorems and their applications in the study of light Higgs boson interactions with mesons and baryons. In particular, we clarify how a new parameter (the A parameter) emerges when the chiral Lagrangian method is combined with the Higgs low-energy theorems to obtain predictions for the interaction of Higgs bosons and pseudoscalar mesons. The computation of the Higgs–nucleon coupling and the branching ratios for light Higgs boson production in the decays K → πH and η′ → ηH are illustrated.
N = 3 AND N = 4 SUPERCONFORMAL WZNW SIGMA MODELS IN SUPERSPACE II: THE N = 4 CASE
Authors: IVANOV E. A. , KRIVONOS S. O. , LEVIANT V. M.
Published: November 2004

The issues related to the U (1) × O (4) N = 4 superconformal WZNW sigma models [with the bosonic target spaces U (1) × SU (2) and U (1) × U (1) × O (4)] are investigated in the framework of a 2D N = 4 superspace. We define the corresponding N = 4 supercurrents, both on classical and quantum levels, in terms of the basic primary N = 4 WZNW superfields and show that the generalized Sugawara form for the dimension 3/2 and 2 component currents directly follows from the constraints on the basic superfields. The N = 4 superfield analog of the Knizhnik–Zamolodchikov equation for conformal blocks in WZNW sigma models is derived. We also analyze the N = 4 WZNW superfields from the standpoint of two SU(2) N = 4 SCAs entering as subalgebras into the underlying U (1) × O (4) N = 4 SCA. We demonstrate that in the linearizing limit the U (1) × SU (2) WZNW model reproduces the recently discussed SU(2) N = 4 superconformal system of free chiral superfields.
THE CHERN–SIMONS TERM AND THE DYNAMICS OF THE CPn−1 MODEL IN THREE DIMENSIONS
Authors: ABDALLA E. , DE CARVALHO F. M.
Published: November 2004

We analyze the phase structure of the CPn−1 model in three-dimensional space–time coupled to fermions, paying special attention to the role played by the Chern–Simons term generated by the fermions. A rich phase structure arises from the large-n expansion.
THE UNIVERSAL LINK POLYNOMIAL
Authors: GUADAGNINI E.
Published: November 2004

The solution of the non-Abelian SU (N) quantum Chern–Simons field theory defined in R3 is presented. It is shown how to compute the expectation values of the Wilson line operators, associated with oriented framed links, in closed form. The main properties of the universal link polynomial, defined by these expectation values, are derived in the case of a generic real simple Lie algebra. The resulting polynomials for some simple examples of links are reported.
THE SUPERCONFORMAL MASTER EQUATION
Authors: GIVEON A. , HALPERN M. B. , KIRITSIS E. B. , OBERS N. A.
Published: November 2004

We obtain the superconformal master equation, which collects the superconformal solutions of the Virasoro master equation on gx × SO (p, q)1. The associated super C-function and super C-theorem are also obtained. A high-level expansion of the superconformal ansatz { SO (n) diag × SO [ dim SO (n)]1}N=1 shows a large class of new, generically irrational superconformal field theories with a three-form living on the signed graphs of order n. The extension to general N = 2 superconformal symmetry is also given.
WIGNER THEORY OF THE NAMBU STRING: (I) THE OPEN STRING
Authors: COLOMO F. , LUSANNA L.
Published: November 2004

A set of relative variables for the open string with P2>0 is found, which has Wigner covariance properties. It allows one to obtain global Lorentz-invariant abelianizations of the constraints, and then to find global Lorentz-invariant canonically conjugated gauge variables. By means of the multitemporal approach a noncanonical redundant set of Dirac observables is defined; these transform as spin-1 Wigner vectors and satisfy constraints of the type of σ models. The generalized Virasoro algebra, except for L0, lives entirely in the gauge sector of the theory. The original canonical variables are expressed by means of the resulting generalized harmonic analysis in terms of these observables, and of the noncovariant center-of-mass ones. Quantization is not done, because a canonical basis of observables is still lacking, but the program to find them is expounded: instead of making a reduction from O (D–1)(P) to O (D–2), which would give a nonlinear realization of the Poincaré group like in the noncovariant approach, one has to find a Thomas-spin-adapted basis of observables which are Lorentz-invariant (except for three of them).
DIMENSIONAL REDUCTION AND THE DUALITY SYMMETRY IN THE SUPERSTRING THEORY
Authors: POLLOCK M.D.
Published: November 2004

The D-dimensional superstring theory is known to be invariant under the duality symmetry b ↔ α'/b, where [Formula: see text] is the constant radius of the N-dimensional internal space and α′ is the slope parameter, the (M+1)-dimensional physical space-time being flat, where D= M+N+1. It is shown, starting from the D-dimensional, vacuum Einstein theory, that this symmetry can be generalized to a curved space-time, with β(t)=–α(t) and [Formula: see text], where t is comoving time, but it will only be an isometry of the (conformally transformed) physical space if this is characterized by a single radius function eα(t). This would explain the homogeneity, isotropy and flatness of the Universe. The dimensionalities are uniquely determined by the dimensional reduction to be D=10, M=3, N=6. Further aspects of the duality symmetry are discussed and the notion of a negative dimension is introduced. For the closed type I superstring, density fluctuations sufficient to account for the presence of galaxies will be present, provided that Gμ≲10−6, where [Formula: see text] is the Newtonian gravitational constant, MP is the Planck mass and μ=α′2/2πb6 is the effective mass per unit length of the string. This condition agrees with the estimate [Formula: see text], obtained by Klein via quantization of the electric charge in the Kaluza-Klein theory. It is also in accord with the expectation that all the higher-dimensional superstring scales are of approximately the same order of magnitude.
N-PARTICLE PROBLEM IN QUANTUM FIELD THEORY AND THE FUNCTIONAL LEGENDRE TRANSFORMS
Authors: PIS'MAK YU. M.
Published: November 2004

The Bethe–Salpeter equations for the n-particle irreducible Green functions in quantum field theory are derived. Their kernels are expressed in terms of the functional Legendre transforms, and n-particle irreducibility of the perturbation theory graphs for the kernel of the n-particle equation is proved. The method for obtaining the Faddeev–Yakubovski equations in quantum field theory is demonstrated for the three-particle case.
TWO-BODY MESONIC DECAYS OF B MESONS IN SU(4)
Authors: SHEIKHOLESLAMI S.M. , VERMA R.C.
Published: November 2004

Two-body B→PP decays are studied by using SU(4) transformation properties of the effective weak nonleptonic Hamiltonian. Decay amplitudes and branching relations are obtained in the SU(4) framework.
ζ-FUNCTION TECHNIQUE FOR QUANTUM COSMOLOGY: THE CONTRIBUTIONS OF MATTER FIELDS TO THE HARTLE-HAWKING WAVE FUNCTION OF THE UNIVERSE
Authors: KAMENSHCHIK A. YU. , MISHAKOV I.V.
Published: November 2004

We investigate the contributions of matter fields to the Hartle-Hawking wave function of the Universe in the one-loop approximation. The values ζ(0), which describe the scaling behavior of the wave function calculated on the background representing the part of four-dimensional DeSitter sphere, are calculated for scalar, electromagnetic, graviton, spin-1/2 and spin-3/2 fields. The ζ-function technique is used and developed for these calculations. The obtained results can be applied to a detailed investigation of the structure of the Hartle-Hawking wave function.
MANIFEST COVARIANCE CONDITION IN THE HAMILTONIAN THEORY OF RELATIVISTIC STRINGS
Authors: GRIGORE D.R.
Published: November 2004

The manifest covariance condition of Currie, Jordan and Sudarshan is generalized in a natural manner to the theory of one relativistic string. Then, all “local” solutions of a certain type (suggested by the existing literature) are classified. It is not clear if one of them corresponds to the usual string theory based on the Nambu-Goto Lagrangian. The analysis is performed in the framework of the Hamiltonian formalism.
PLANAR DOMAIN WALLS COUPLED WITH PURE RADIATION FIELDS
Authors: WANG ANZHONG
Published: November 2004

All the exact solutions of the Einstein-Maxwell-Weyl equations are given, which represent planar domain walls coupled with electromagnetic and neutrino radiation fields. Some specific solutions are studied.
SOLITON EQUATIONS, MINIMAL KAZAMA-SUZUKI MODELS AND 2-DIMENSIONAL GRAVITY
Authors: LACKI JAN
Published: November 2004

We propose a framework relating the integrable structures appearing in k-matrix models with algebraic data of the corresponding N=2 Kazama-Suzuki models. Both the generalized KdV flows and the Virasoro constraints are obtained. The carrier spaces of the basic, principally realized representations of the corresponding affine algebras [Formula: see text] appear to constitute natural infinite “gravitational” analogs of the chiral rings of the associated Kazama-Suzuki models.
MODULAR INVARIANT ONE-POINT CORRELATION FUNCTIONS FOR SU(2) WESS-ZUMINO MODEL
Authors: ANDREEV O.D.
Published: November 2004

We calculate one-point correlation functions of SU(2) Wess-Zumino model (WZM) on a torus using the Wakimoto free field representation. Their modular invariance is proved. It is a necessary condition of extending the WZ conformal field theory to higher genus Riemann surfaces.
LAX-PAIR FORMULATION OF THE W-GRAVITY THEORIES IN TWO DIMENSIONS
Authors: JEAN-MARC LINA , PANIGRAHI PRASANTA K.
Published: November 2004

The Lax-pair formulation of the two-dimensional induced gravity in the light-cone gauge is extended to the more general wN theories. After presenting the w2 and w3 gravities, we give a general prescription for an arbitrary wN case. This is further illustrated with the w4 gravity to point out some peculiarities. The constraints and the possible presence of the cosmological constants are systematically exhibited in the zero-curvature condition, which also yields the relevant Ward identities. The restrictions on the gauge parameters in the presence of the constraints are pointed out too, and are contrasted with those of the ordinary 2D gravity.
CURRENT STATUS OF PROPERTIES AND SIGNALS OF THE QUARK-GLUON PLASMA
Authors: SINGH C.P.
Published: November 2004

Heavy ion experiments at the AGS machine of Brookhaven National Laboratory and SPS of CERN are aimed at producing and diagnosing a new state of matter, the quark-gluon plasma. Some important and relevant issues involving the nature and the detection aspects of the phase transition from hadron to quark matter are reviewed in an introductory and pedagogical way.
PHASE TRANSITIONS IN STRONG COUPLING QED4[N]
Authors: ATKINSON D. , GROOT H.J. DE , JOHNSON P.W.
Published: November 2004

We analyze coupled Dyson-Schwinger equations for massless fermion and photon propagators in QED4[N], taking proper account of charge renormalization. With one fermion flavor, we find a fixed point at an ultraviolet “fine-structure constant” of 2.10, corresponding to a phase transition (associated with the dynamical breaking of chiral symmetry) of mean-field type.
TESTING CONTACT INTERACTIONS OF QUARKS AND GLUONS AT FUTURE pp COLLIDERS
Authors: ARGYRES E.N. , KATSILIERIS G.A. , PAPADOPOULOS C.G. , VLASSOPULOS S.D.P.
Published: November 2004

We calculate the contributions of the allowed qqqq, GGG, GGGG, qqG and qqGG contact interactions of the standard QCD quarks and gluons, at a common scale Λ, to jet cross sections at the future hadron colliders. Assuming that the two-jet normalized angular-distribution measurements will be consistent with QCD, to 95% CL we obtain bounds Λ>35–40 TeV at LHC or Λ>50–80 TeV at SSC. A similar analysis of the three-jet events would give Λ>13–15 TeV or Λ>10–25 TeV, respectively.
SPECTRUM AND COMPLETENESS OF THE INTEGRABLE 3-STATE POTTS MODEL: A FINITE SIZE STUDY
Authors: ALBERTINI GIUSEPPE , DASMAHAPATRA SRINANDAN , MCCOY BARRY M.
Published: November 2004

All eigenvalues of the transfer matrix of the integrable 3-state Potts model are computed as polynomials in the spectral variable for chains of length M ≤7. The zeroes of the eigenvalues are known to satisfy a Bethe's Ansatz equation and thus it is of particular interest that we find many solutions whose zeroes do not satisfy the traditional "string hypothesis". We also find many cases where the integers in the logarithmic form of the Bethe equations do not satisfy the monotonicity properties that they are usually assumed to possess. We present a classification of all eigenvalues in terms of sets of roots and show that, for all M, this classification yields a complete set.
THE ANNIHILATING IDEALS OF MINIMAL MODELS
Authors: FEIGIN BORIS L. , NAKANISHI TOMOKI , OOGURI HIROSI
Published: November 2004

We describe several aspects of the annihilating ideals and reduced chiral algebras of conformal field theories, especially, minimal models of Wn algebras. The structure of the annihilating ideal and a vanishing condition is given. Using the annihilating ideal, the structure of quasi-finite models of the Virasoro (2,q) minimal models are studied, and their intimate relation to the Gordon identities are discussed. We also show the examples in which the reduced algebras of Wn and Wℓ algebras at the same central charge are isomorphic to each other.
ON COMMUTANTS, DUAL PAIRS AND NON-SEMISIMPLE ALGEBRAS FROM STATISTICAL MECHANICS
Authors: MARTIN PAUL P. , MCANALLY DAVID S.
Published: November 2004

For M a finite dimensional complex vector space and A a certain type of (unital) subalgebra of End(M) (including some specific types of physical significance in the field of quantum spin chains) we give an algorithm for constructing the centraliser or commutant B of A on M. We give examples, and discuss the conditions for centralising to be an involution, i.e. A, B a dual pair, and for B and A to be Morita equivalent. A special case of one example shows that Hn(q), Uq(sl2) act as a dual pair on the tensored vector representation for all q.
CHARACTER TABLE OF HECKE ALGEBRA OF TYPE AN-1 AND REPRESENTATIONS OF THE QUANTUM GROUP Uq(gln+1)
Authors: UENO Kimio , SHIBUKAWA Youichi
Published: November 2004

A q-analogue of the Frobenius formula is proved by means of the quantum groups Uq(gln+1), Aq(GLn+1) and Iwahori's Hecke algebra of type AN-1, and then, the character table of this Hecke algebra is investigated.
APPLICATION OF A REAL-TIME CONTROL STRATEGY FOR BAYESIAN BELIEF NETWORKS TO SHIP CLASSIFICATION PROBLEM SOLVING
Authors: MUSMAN S.A. , CHANG L.W. , BOOKER L.B.
Published: November 2004

Many classification problems must be performed in a timely or time constrained manner. For this reason, the generation of control schemes which are capable of responding in real-time are fundamental to many applications. For our problem, that of ship classification, tactical scenarios often dictate the response time required from a system.

In this paper, we discuss efficient ways to prioritize and gather evidence within belief networks. We also suggest ways in which we can structure our large problem into a series of small ones. This both pre-defines much of our control strategy into the system structure and also localizes our run-time control issues into much smaller networks. The overall control strategy thus includes the combination of both of these methods. By combining them correctly we can reduce the amount of dynamic computation required during run-time and thus improve the responsiveness of the system.
PARSING-DRIVEN GENERALIZATION FOR NATURAL LANGUAGE ACQUISITION
Authors: LIU REY-LONG , SOO VON-WUN
Published: November 2004

Parsing is an important step in natural language processing. It involves tasks of searching for applicable grammatical rules which can transform natural language sentences into their corresponding parse trees. Therefore parsing can be viewed as problem solving, and language acquisition can be achieved by generalizing problem solving heuristics. In this paper we investigate how machine learning methodologies can be integrated with a Wait-And-See Parser (the problem solver) to acquire parsing-related knowledge that is needed for the parser. We call this approach parsing-driven generalization since learning (acquisition of parsing rules and classification of lexicons) is basically derived from the parsing process.

Three types of generalization are reported in this paper: simple generalization, generalization by asking questions, and generalization back-propagation. Simple generalization generalizes any two parsing rules whose action parts (right-hand sides) are the same but whose condition parts (left-hand sides) have a single difference. Generalization by asking questions is triggered when a “climbing-up” move on a concept hierarchy is attempted. It is necessary for avoiding over-generalization. Generalization back-propagation propagates a confirmed generalization of some later parsing rule back to its precedent rules in a parsing sequence and thus causes them to be generalized as well. It can reduce the number of questions asked by the system. With these three types of generalization and a mechanism for maintaining lexicon classification (the domain concept hierarchy), parsing and learning can interact to utilize and acquire parsing-related knowledge. To promote the practical performance of parsing after learning, a relaxation parsing mechanism is also designed to process unseen sentences.
AN INTEGRATED ARCHITECTURE FOR RECOGNITION OF TOTALLY UNCONSTRAINED HANDWRITTEN NUMERALS
Authors: GUPTA AMAR , NAGENDRAPRASAD M.V. , LIU A. , WANG P.S.P. , AYYADURAI S.
Published: November 2004

A multi-staged system for off-line handwritten numeral recognition is presented here. After scanning, the digitized binary bitmap image of the source document is passed through a preprocessing stage which performs segmentation, thinning and rethickening, normalization, and slant correction. The recognizer is a three-layered neural net trained with back-propagation algorithm. While a few systems that use three-layered nets for recognition have been presented in the literature, the contribution of our system is based on two aspects: elaborate preprocessing based on structural pattern recognition methods combined with a neural net based recognizer; and integration of neural net based and structural pattern recognition methods to produce high accuracies.
HYBRID NEURAL NETWORK/HIDDEN MARKOV MODEL SYSTEMS FOR CONTINUOUS SPEECH RECOGNITION
Authors: MORGAN NELSON , BOURLARD HERVÉ , RENALS STEVE , COHEN MICHAEL , FRANCO HORACIO
Published: November 2004

MultiLayer Perceptrons (MLP) are an effective family of algorithms for the smooth estimation of highly-dimensioned probability density functions that are useful in continuous speech recognition. Hidden Markov Models (HMM) provide a structure for the mapping of a temporal sequence of acoustic vectors to a generating sequence of states. For HMMs that are independent of phonetic context, the MLP approaches have consistently provided significant improvements (once we learned how to use them). Recently, these results have been extended to context-dependent models.

In this paper, after having reviewed the basic principles of our hybrid HMM/MLP approach, we describe a series of experiments with continuous speech recognition. The hybrid methods directly trade off computational complexity for reduced requirements of memory and memory bandwidth. Results are presented on the widely used Resource Management speech database that is distributed by the National Institute of Standards and Technology. These results demonstrate performance that is at least as good as any other reported continuous speech recognition system (for this task).
A THINNING ALGORITHM BASED ON THE FORCE BETWEEN CHARGED PARTICLES
Authors: ARUMUGAM AKILA , RADHAKRISHNAN T. , SUEN C.Y. , WANG P.S.P.
Published: November 2004

A new thinning algorithm based on the well known concept of the force of attraction or repulsion between charged particles is presented. This algorithm generates connected skeletons which preserve the shape and end-points of the original patterns. Its performance is experimentally compared with four other known algorithms published in the literature. For the sake of comparison, a reasoned set of test data is introduced. The results of our comparison reveal that the proposed CPM (Charge Particle Method) algorithm is almost as fast as the fastest of those compared. For thin images obtainable from low resolution scanners or coarse scanned images, the CPM algorithm is the fastest.