bluuebunny/crossref_metadata_2025 huggingface dataset:
Streptococcal Pyrogenic Exotoxin B-Induced Apoptosis in A549 Cells Is Mediated by a Receptor- and Mitochondrion-Dependent Pathway
Authors: Tsai Wan-Hua , Chang Chia-Wen , Chuang Woei-Jer , Lin Yee-Shin , Wu Jiunn-Jong , Liu Ching-Chuan , Chang Wen-Tsan , Lin Ming T.
Published: November 2004

It has been shown that streptococcal pyrogenic exotoxin B (SPE B) can induce cells to undergo apoptosis. The present study is to dissect the role of SPE B protease and SPE B protein in the apoptotic process of A549 cells and to elucidate the SPE B-induced apoptotic pathway. Recombinant SPE B (rSPE B) and C192S, a mutant of SPE B without protease activity, were expressed in
Escherichia coli
and purified by using an affinity column. The apoptosis of A549 cells was assayed by propidium iodide staining, followed by flow cytometry analysis. Our results showed that SPE B induced apoptosis in a dose-dependent manner, whereas C192S did not. When cells were pretreated with rSPE B (2 μg/ml) for as briefly as 5 min and then incubated with C192S of 28 kDa, an apoptosis that is proportional to the period of pretreatment was observed but not with C192S of 42 kDa. These results suggest that the extracellular protease activity of rSPE B is required for the initiation of apoptosis and that the size of SPE B is important for an effective induction of apoptosis. The time course analysis revealed that molecules activated in apoptosis were in the following order: caspase-8 (1.5 h), t-Bid (2.5 h), Bax (3 h), cytochrome
c
release (6 h), caspase-9 (7 h), and caspase-3 (8 h). The overexpression of Bcl-2 inhibited depolarization of mitochondrial membrane, cytochrome
c
release, and apoptosis. The results of the present study suggest that SPE B-induced apoptosis is mediated through a receptor-like mechanism and a mitochondrion-dependent pathway.
Capsule Polysaccharide Mediates Bacterial Resistance to Antimicrobial Peptides
Authors: Campos Miguel A. , Vargas Miguel A. , Regueiro Verónica , Llompart Catalina M. , Albertí Sebastián , Bengoechea José A.
Published: November 2004

The innate immune system plays a critical role in the defense of areas exposed to microorganisms. There is an increasing body of evidence indicating that antimicrobial peptides and proteins (APs) are one of the most important weapons of this system and that they make up the protective front for the respiratory tract. On the other hand, it is known that pathogenic organisms have developed countermeasures to resist these agents such as reducing the net negative charge of the bacterial membranes. Here we report the characterization of a novel mechanism of resistance to APs that is dependent on the bacterial capsule polysaccharide (CPS).
Klebsiella pneumoniae
CPS mutant was more sensitive than the wild type to human neutrophil defensin 1, β-defensin 1, lactoferrin, protamine sulfate, and polymyxin B.
K. pneumoniae
lipopolysaccharide O antigen did not play an important role in AP resistance, and CPS was the only factor conferring protection against polymyxin B in strains lacking O antigen. In addition, we found a significant correlation between the amount of CPS expressed by a given strain and the resistance to polymyxin B. We also showed that
K. pneumoniae
CPS mutant bound more polymyxin B than the wild-type strain with a concomitant increased in the self-promoted pathway. Taken together, our results suggest that CPS protects bacteria by limiting the interaction of APs with the surface. Finally, we report that
K. pneumoniae
increased the amount of CPS and upregulated
cps
transcription when grown in the presence of polymyxin B and lactoferrin.
Oral Vaccination with Recombinant
Yersinia enterocolitica
Expressing Hybrid Type III Proteins Protects Gerbils from Amebic Liver Abscess
Authors: Lotter Hannelore , Rüssmann Holger , Heesemann Jürgen , Tannich Egbert
Published: November 2004

Protection against invasive amebiasis was achieved in the gerbil model for amebic liver abscess by oral immunization with live attenuated
Yersinia enterocolitica
expressing the
Entamoeba histolytica
galactose-inhibitable lectin that has been fused to the
Yersinia
outer protein E (YopE). Protection was dependent on the presence of the YopE translocation domain but was independent from the antibody response to the ameba lectin.
Bacteriophage MAV1 Is Not Associated with Virulence of
Mycoplasma arthritidis
Authors: Clapper Brenda , Tu Anh-Hue T. , Simmons Warren L. , Dybvig Kevin
Published: November 2004

Previous studies demonstrated that
Mycoplasma arthritidis
strain 158 acquired a high degree of virulence upon lysogenization with bacteriophage MAV1. In the present study, the association between MAV1 and virulence was reexamined by creating new lysogens of 158 and of a relatively avirulent mutant, strain 158-1. In the absence of lysogenization, 158 was more virulent than expected. The virulence of 158 and 158-1 did not increase upon lysogenization. A major antigenic difference between 158 and 158-1 was identified that is unrelated to MAV1 and could account for the difference in virulence.
The Calcineurin Target, Crz1, Functions in Azole Tolerance but Is Not Required for Virulence of
Candida albicans
Authors: Onyewu Chiatogu , Wormley Floyd L. , Perfect John R. , Heitman Joseph
Published: November 2004

In
Candida albicans
, calcineurin is essential for virulence and survival during membrane perturbation by azoles. Crz1 is a proposed downstream target of calcineurin based on studies of
Saccharomyces cerevisiae
. However, the in vitro phenotypes of
C. albicans crz1/crz1
and calcineurin mutants differ and Crz1 is not required for virulence.
Evaluation of the Role of Constitutive Isocitrate Lyase Activity inYersinia pestisInfection of the Flea Vector and Mammalian Host
Authors: Sebbane Florent , Jarrett Clayton O. , Linkenhoker Jan R. , Hinnebusch B. Joseph
Published: November 2004

Yersinia pestis, unlike the closely relatedYersinia pseudotuberculosis, constitutively produces isocitrate lyase (ICL). Here we show that theY. pestis aceAhomologue encodes ICL and is required for growth on acetate but not for flea infection or virulence in mice. Thus, deregulation of the glyoxylate pathway does not underlie the recent adaptation ofY. pestisto arthropod-borne transmission.
Pigeon-Associated Strains of
Salmonella enterica
Serovar Typhimurium Phage Type DT2 Have Genomic Rearrangements at rRNA Operons
Authors: Helm R. Allen , Porwollik Steffen , Stanley April E. , Maloy Stanley , McClelland Michael , Rabsch Wolfgang , Eisenstark Abraham
Published: November 2004

Strains from a subgroup of
Salmonella enterica
serovar Typhimurium frequently associated with pigeon infections were tested for genomic anomalies and virulence in mice. Some strains have a genomic inversion between
rrn
operons. Two prophages found in the common laboratory strain LT2 were absent. Pigeon-associated strains are still virulent in mice.
Random walks and related diffusion equations
Authors: Moretti P , Lantieri M , Cianchi L
Published: November 2004

The one-dimensional random walk between two reflecting walls is considered from two different points of view: the first, as a particular case of jumps between neighbouring, discrete states; the second, as a system that obeys a generalized diffusion equation. By performing the suitable limits, the identity of the two results is pointed out and a physical application is presented. PACS Nos.: 02.50.Ey, 02.30.Jr
Testing hypotheses of bison population decline (1970–1999) in Wood Buffalo National Park: synergism between exotic disease and predation
Authors: Joly Damien O , Messier François
Published: November 2004

One hypothesis to explain the decline of bison (Bison bison (L., 1758)) abundance in Wood Buffalo National Park, Canada, is the "disease–predation" hypothesis where tuberculosis (Mycobacterium bovis Karlson and Lessel, 1970) and brucellosis (Brucella abortus (Schmidt, 1901)) reduce bison survival and reproduction, thus shifting bison abundance from a high-density, food-regulated equilibrium to a low-density, predator-regulated equilibrium. We use historical data on bison abundance and stochastic population simulation to examine this hypothesis. A decline in only one area of the park would discount disease as a factor, because exotic disease is present throughout the park; however, we found that decline rates were similar in the two main populations of bison. Using simulation, we found a high (68.5%) probability that a tuberculosis- and brucellosis-infected bison population experiencing predation by wolves (Canis lupus L., 1758) would stabilize at low densities (<0.83 bison/km2), which increased to 93.6% when anthrax and drowning were considered to be mortality sources. In the absence of tuberculosis and brucellosis, there was a low probability that bison would persist at this low density (<8%). These simulations suggest that an interaction between tuberculosis, brucellosis, and predation may account for the decline of bison abundance in Wood Buffalo National Park from 1970 to 1999.
BANISHING ROBUST TURING COMPLETENESS
Authors: HEMASPAANDRA LANE A. , JAIN SANJAY , VERESHCHAGIN NIKOLAI K.
Published: November 2004

This paper proves that “promise classes” are so fragilely structured that they do not robustly (i.e. with respect to all oracles) possess Turinghard sets even in classes far larger than themselves. In particular, this paper shows that FewP does not robustly possess Turing hard sets for UP∩coUP and IP∩coIP does not robustly possess Turing hard sets for ZPP. It follows that ZPP, R, coR, UP∩coUP, UP, FewP∩coFewP, FewP, and IP∩coIP do not robustly possess Turing complete sets. This both resolves open questions of whether promise classes lacking robust downward closure under Turing reductions (e.g., R, UP, FewP) might robustly have Turing complete sets, and extends the range of classes known not to robustly contain many-one complete sets.
LEARNING CONSTRAINTS IN STORAGE CAPACITY IN NETWORKS WITH DYNAMIC SYNAPSES
Authors: Fusi Stefano , Amit Daniel J.
Published: November 2004

Some constraints intrinsic to unsupervised learning in attractor neural networks (ANN) are discussed. We present a very simple realizable model of ANN capable of dynamically learning and classifying input stimuli in a totally unsupervised fashion. The synapses of the network are analog dynamic variables whose values have to be periodically refreshed to avoid memory loss. Two refreshing mechanisms are discussed: the first one is a periodic deterministic refresh while the second one acts stochastically. Then some typical learning scenarios are described and constraints on storage capacity are exposed: in the worst case a network of N neurons can learn at most O(ln N) patterns while in the best case (stochastic learning) the number of stored patterns cannot surpass [Formula: see text]. We have come across these constraints in connection with a design of an organically learning ANN, implemented in silicon.
THE GENERALIZATION OF A CONSTRUCTIVE ALGORITHM IN PATTERN CLASSIFICATION PROBLEMS
Authors: Burgess Neil , Di Zenzo Silvano , Ferragina Paolo , Granieri Mario Notturno
Published: November 2004

The use of a constructive algorithm for pattern classification is examined. The algorithm, a ‘Perceptron Cascade’, has been shown to converge to zero errors whilst learning any consistent classification of real-valued pattern vectors (Burgess, 1992). Limiting network size and producing bounded decision regions are noted to be important for the generalization ability of a network. A scheme is suggested by which a result on generalization (Vapnik, 1992) may enable calculation of the optimal network size. A fast algorithm for principal component analysis (Sirat, 1991) is used to construct ‘hyper-boxes’ around each class of patterns to ensure bounded decision regions. Performance is compared with the Gaussian Maximum Likelihood procedure in three artificial problems simulating real pattern classification applications.
MACHINE APPROACHES TO PROTEIN FEATURE PREDICTION
Authors: Tcheng David K. , Subramaniam Shankar
Published: November 2004

Knowledge-based approaches are being increasingly used in predicting protein structure and motifs. Machine learning techniques such as neural networks and decision-trees have become invaluable tools for these approaches. This paper describes the use of machine learning in predicting sequence-based motifs in antibody fragments. Given the limited number of three dimensional structures and the plethora of sequences, this technique is useful for homology modeling of three dimensional structures of antibody fragments.
NEURAL NETWORK DISCRIMINATION OF HEAVY FLAVOR JETS: A SURVEY
Authors: Mazzanti P. , Odorico R.
Published: November 2004

A short survey of the use of neural networks and statistical discriminants in high energy physics for recognition of heavy flavor jets is presented. After illustrating the various neural and statistical classifiers currently used, some assessment of their comparative performance for top and bottom jets is made.
CHOICE OF ATOMIC PARAMETERS FOR THEORETICAL CALCULATIONS OF L X-RAY PRODUCTION CROSS SECTIONS
Authors: KAUR RAVINDER , SINGH SATINDER
Published: November 2004

Photon-induced L X-ray production cross sections have been calculated for even Z in the region Z=40–92 at different excitation energies. The results have been compared with the experimental values, and the effects of the choice of atomic parameters — like fluorescence yields, Coster-Kroning transition probabilities and relative emission rates — used in calculating L X-ray production cross sections have been discussed.
DESCRIPTION OF BACKGROUND COMPONENT AND PEAK SHAPE IN ENERGY-DISPERSIVE X-RAY SPECTRA
Authors: Gerasimov S.A. , Arzhanova I.G.
Published: November 2004

The procedures for the estimation of background and the analytical representation of peak shape are described. The method for the background evaluation is outlined without using peak-free regions in spectrum. The expression for the response function is simple and reproduces experimental data for a wide range of channel numbers and peak positions.
THE SUPERCOMPUTER TOOLKIT: A GENERAL FRAMEWORK FOR SPECIAL-PURPOSE COMPUTING
Authors: ABELSON HAROLD , BERLIN ANDREW A. , KATZENELSON JACOB , McALLISTER WILLIAM H. , ROZAS GUILLERMO J. , SUSSMAN GERALD JAY , WISDOM JACK
Published: November 2004

The Supercomputer Toolkit is a family of hardware modules (processors, memory, interconnect, and input-output devices) and a collection of software modules (compilers, simulators, scientific libraries, and high-level front ends) from which high-performance special-purpose computers can be easily configured and programmed. Although there are many examples of special-purpose computers (see Ref. 4), the Toolkit approach is different in that our aim is to construct these machines from standard, reusable parts. These are combined by means of a user-reconfigurable, static interconnect technology. The Toolkit’s software support, based on novel compilation techniques, produces extremely high-performance numerical code from high-level language input.

We have completed fabrication of the Toolkit processor module, and several critical software modules. An eight-processor configuration is running at MIT. We have used the prototype Toolkit to perform a breakthrough computation of scientific importance—an integration of the motion of the Solar System that extends previous results by nearly two orders of magnitude.

While the Toolkit project is not complete, we believe our results show evidence that generating special-purpose computers from standard modules can be an important method of performing intensive scientific computing. This paper briefly describes the Toolkit’s hardware and software modules, the Solar System simulation, conclusions and future plans.
SYSTOLIC ALGORITHMS FOR RECURSIVE TOTAL LEAST SQUARES PARAMETER ESTIMATION AND MIXED RLS/RTLS PROBLEMS
Authors: MOONEN MARC
Published: November 2004

Total least squares parameter estimation is an alternative to least squares estimation though much less used in practice, partly due to the absence of efficient recursive algorithms or parallel architectures. Here it is shown how previously developed systolic algorithms/architectures for recursive least squares estimation can be used for recursive total least squares problems. Unconstrained as well as linearly constrained and "mixed RLS/RTLS" problems are considered.
THE DESIGN OF A VERY HIGH PERFORMANCE IIR FILTER CHIP
Authors: McNALLY O. C. , McCANNY J. V. , WOODS R. F.
Published: November 2004

The design of a high performance bit parallel second order IIR filter chip is described. The chip in question is highly pipelined, uses most significant digit first arithmetic and consists mainly of arrays of simple carry–save adders. It has been fabricated in 1.5 μm double level metal CMOS technology, accepts 12 bit input data and coefficient values and can operate at up to 40 megasamples per second. All data inputs and outputs are in two's complement form and the chip power consumption is 1 W. The highly regular nature of the architecture has been exploited for test pattern generation. It is shown how small, but important modifications to the basic architecture, can significantly improve testing. As a result, 100% fault coverage can be achieved using less than 1000 test vectors. The chip may be used in a cascade realisation to form a general Nth order filter.
PARALLEL COMPUTING IN MULTIDIMENSIONAL RECURSIVE FILTERING
Authors: LIU XIAOJIAN , BRUTON LEONARD T.
Published: November 2004

This paper introduces and generalizes a number of multidimensional (MD) recursive parallel filter algorithms, which are based on the principles of orthogonal and diagonal computing, respectively. Efficient software and hardware implementation methods for the proposed parallel algorithms are presented. In particular, it is shown that systolic array implementations can be achieved for MD parallel filter structures that are locally interconnected and have a critical path of 1 multiplication plus 1 addition. In this way, the proposed parallel filters are easily able to perform real-time processing at video rates.
GEODESICS AND OPERATOR MEANS IN THE SPACE OF POSITIVE OPERATORS
Authors: CORACH GUSTAVO , PORTA HORACIO , RECHT LÁZARO
Published: November 2004

The set A+ of positive invertible elements of a C*-algebra has a natural structure of reductive homogeneous manifold with a Finsler metric. Because pairs of points can be joined by uniquely determined geodesics and geodesics are "short" curves, there is a natural notion of convexity: C ⊂ A+ is convex if the geodesic segment joining a, b ∈ C is contained in C. We show that this notion is related to the classical convexity of real and operator valued functions. Several results about convexity are proved in this paper. The expressions of these results are closely related to the operator means of Kubo and Ando, in particular to the geometric mean of Pusz and Woronowicz, and they produce several norm estimations and operator inequalities.
HOMOGENEOUS VECTOR BUNDLES AND COWEN-DOUGLAS OPERATORS
Authors: WILKINS DAVID R.
Published: November 2004

In this paper we obtain an algebraic classification of all homogeneous Hermitian holomorphic vector bundles of arbitrary rank over a bounded symmetric domain. This classification result is used in order to classify, up to unitary equivalence, all irreducible homogeneous bounded linear operators on a separable infinite-dimensional Hilbert space that belong to the Cowen-Douglas class B2 (∆), where ∆ is the open unit disk.
DENSE m-CONVEX FRÉCHET SUBALGEBRAS OF OPERATOR ALGEBRA CROSSED PRODUCTS BY LIE GROUPS
Authors: SCHWEITZER LARRY B.
Published: November 2004

Let A be a dense Fréchet *-subalgebra of a C*-algebra B. (We do not require Fréchet algebras to be m-convex.) Let G be a Lie group, not necessarily connected, which acts on both A and B by *-automorphisms, and let σ be a sub-polynomial function from G to the nonnegative real numbers. If σ and the action of G on A satisfy certain simple properties, we define a dense Fréchet *-subalgebra G ⋊σ A of the crossed product L1 (G, B). Our algebra consists of differentiable A-valued functions on G, rapidly vanishing in σ.

We give conditions on σ and the action of G on A which imply the m-convexity of the dense subalgebra G ⋊σ A. A locally convex algebra is said to be m-convex if there is a family of submultiplicative seminorms for the topology of the algebra. The property of m-convexity is important for a Fréchet algebra, and is useful in modern operator theory.

If G acts as a transformation group on a locally compact space M, we develop a class of dense subalgebras for the crossed product L1 (G, C0 (M)), where C0 (M) denotes the continuous functions on M vanishing at infinity with the sup norm topology. We define Schwartz functions S (M) on M, which are differentiable with respect to some group action on M, and are rapidly vanishing with respect to some scale on M. We then form a dense Fréchet *-subalgebra G ⋊σ S (M) of rapidly vanishing, G-differentiable functions from G to S (M).

If the reciprocal of σ is in Lp (G) for some p, we prove that our group algebras Sσ (G) are nuclear Fréchet spaces, and that G ⋊σ A is the projective completion [Formula: see text].
MODULI OF STABLE PAIRS FOR HOLOMORPHIC BUNDLES OVER RIEMANN SURFACES II
Authors: BRADLOW STEVEN , DASKALOPOULOS GEORGIOS D.
Published: November 2004

In this paper we continue our investigation of the moduli space of stable pairs introduced in Part I. We obtain certain topological information, and we give a proof that this moduli space admits the structure of a nonsingular projective variety. We show that the natural map from the moduli space of stable pairs onto the Seshadri compactification of stable bundles is a morphism of algebraic varieties.
CLUSTER ALGORITHMS FOR NONLINEAR SIGMA MODELS
Authors: WOLFF ULLI
Published: November 2004

Percolation cluster Monte Carlo algorithms for nonlinear σ-models on the lattice are reviewed with special emphasis on their possible generalizations. While they have been found to practically eliminate critical slowing down for the standard O(n) invariant vector models, their extension to other physically similar models — like RPn−1 and SU(n)×SU(n) chiral models — is less straight forward than one might have thought. I outline the present situation in this area of research. In the second part of my talk I described a numerical calculation of a physical running coupling constant in the O(3) model. This represents an application of the cluster technique in a preparatory study for a later lattice gauge theory calculation. This material can be found in Ref. 11.
CLUSTER ALGORITHMS FOR SURFACES
Authors: EVERTZ HANS GERD , HASENBUSCH MARTIN , MARCU MIHAIL , PINN KLAUS , SOLOMON SORIN
Published: November 2004

We discuss a new cluster algorithm that completely eliminates critical slowing down for surface models of the SOS (solid-on-solid) type.
MEASURING COMPLEXITY: A RELATIVE ASPECT OF PATTERN RECOGNITION
Authors: IKEGAMI TAKASHI , TSUDA ICHIRO
Published: November 2004

We propose a new definition of complexity. The degree of complexity depends on the observer’s knowledge and is expressed by templates and their interactions. Complexity of a pattern is measured in a procedure of tiling the pattern with the templates. A new relation of complexity vs. entropy is obtained wherein entropy becomes a function of complexity.
NEURAL NETWORKS IN EXPERIMENTAL HIGH-ENERGY PHYSICS
Authors: BORTOLOTTO C. , ANGELIS A. DE , GROOT N. DE , SEIXAS J.
Published: November 2004

During the last years, the possibility to use Artificial Neural Networks in experimental High Energy Physics has been widely studied. In particular, applications to pattern recognition and pattern classification problems have been investigated. The purpose of this article is to review the status of such investigations and the techniques established.
SURFACE FREE ENERGY OF HADRONIC AND GLUONIC DROPLETS FROM LATTICE QCD
Authors: HUANG S. , POTVIN J. , REBBI C.
Published: November 2004

We present the results of a computation of the surface tension on hadronic and gluonic droplets in finite temperature quenched lattice QCD. The surface free energy was obtained by integrating the average action along a path in coupling space corresponding to growing and melting a spherical droplet of a given radius. So far droplets of radius 4, 5 and 8 (in lattice units) have been considered. After discussing ambiguities in the definition of the surface tension due to a droplet’s finite size and thick interface, we compare our results with the Bag model study of Mardor and Svetitsky. Our calculations appear to confirm qualitatively their prediction of a negative surface tension for hadronic droplets with small radii. A similar result is found for gluonic droplets, in contrast however with the Bag model. We also compare our results with the recent lattice simulation of Kajantie, Karkkainen and Rummukainen.
BARYON TRANSFER THROUGH THE INTERFACE BETWEEN REGIONS OF BROKEN AND RESTORED CHIRAL SYMMETRY
Authors: JAKOVÁC A. , PATKÓS A.
Published: November 2004

The shrinking of a chirally symmetric droplet of finite baryonic charge, immersed into the broken symmetry medium is described. The treatment is parallel to the methods applied in the Skyrme model of the nucleon.
FIRST ORDER PHASE TRANSITIONS IN THE BINARY PERCEPTRON
Authors: NICOLIS STAM
Published: November 2004

We present a numerical method for the study of the stability-capacity diagram of the Ising perceptron that is readily scalable, thus providing the opportunity to resolve some open issues on this problem. We also discuss the possibility of studying multi-layer systems.
FINITE SIZE SCALING ON THE ISING COEXISTENCE LINE
Authors: GUPTA SOURENDU , IRBÄCK A.
Published: November 2004

We report tests of finite-size scaling ansatzes in the low temperature phase of the two-dimensional Ising model. For moments of the magnetisation density, we find good agreement with the new ansatz of Borgs and Kotecký, and clear evidence of violations of the double Gaussian ansatz. We note that certain consequences of the convexity of the free energy are not adequately treated in either of these approaches.
CRITICAL SURFACE EXPONENTS IN 2-D 10-STATE POTTS MODEL
Authors: KÄRKKÄINEN LEO , RUMMUKAINEN KARI
Published: November 2004

At low temperature, the Potts models can have interfaces between domains ordered to different directions. We use the difference of periodic and twisted boundary conditions to study planar order-order interfaces. We show that the interface tension, energy and width display critical properties as one approaches the critical point. We measure the critical exponents connected to their power like singular behaviour at the critical point.
WAVELET TRANSFORM ON CONNECTION MACHINE AND SYMPATI 2
Authors: PIC MARC MICHEL , ESSAFI HASSANE
Published: November 2004

The time of computation of Wavelet Transform on classic computers limits its applications in several area of signal processing and data compression. A parallel algorithm to compute the Wavelet Transform is presented in this paper and is ported on two parallel computers: a Connection–Machine 2 and a SYMPATI 2 line–processor.
CELLULAR AUTOMATON FOR THE FRACTURE OF ELASTIC MEDIA
Authors: OSSADNIK PETER
Published: November 2004

We study numerically the growth of a crack in an elastic medium under the influence of a travelling shockwave. We describe the implementation of a fast algorithm which is perfectly suited for a data parallel computer. Using large scale simulations on the Connection Machine we generate cracks with more than 10000 sites on a 1024 × 1024 lattice. We show that the resulting patterns are fractal with a fractal dimension that depends on the chosen breaking criterion and varies between 1. and 2.
A DATA PARALLEL PROBLEM SOLVING ARCHITECTURE FOR THE RECONSTRUCTION OF PHYSICAL EVENTS
Authors: HEMKER ANDREAS
Published: November 2004

A system is presented which is able to reconstruct the physical processes after the annihilation of particles in collider rings like LEP. It can be shown that the reconstruction task belongs to the class of NP-complete problems. Neither the conventional symbol processing approach of artificial intelligence nor connectionist systems alone satisfy the requirements of the application. A hybrid system is introduced in which a genetic algorithm acts together with a model-based hillclimbing component. The power of this method is based on the interaction of a dynamically and an inferentially working module. The inherent parallelism of dynamic systems makes a implementation on a parallel architecture useful. A data parallel implementation of this algorithm on the Connection Machine Model CM-2 is described. At last the reconstruction system is applied to a classification task, the identification of the initial quark pair. The results are compared with a conventional analysis method and a neural network.
FORMATION OF LARGE SCALE STRUCTURES OF THE UNIVERSE ON THE CONNECTION MACHINE-2.
Authors: ALIMI JEAN-MICHEL , SCHOLL HANS
Published: November 2004

We have developped two new N-body codes on Connection Machine 2. We present preliminary results concerning the formation of large scale structure of the Universe.
NUMERICAL IMPLEMENTATION OF A K.A.M. ALGORITHM
Authors: JAUSLIN H. R.
Published: November 2004

We discuss a numerical implementation of a K.A.M. algorithm to determine invariant tori, for systems that are quadratic in the action variables. The method has the advantage that the iteration procedure does not produce higher order terms in the actions, allowing thus a systematic control of the convergence.
PLATO, APOLLONIUS, AND KLEIN: Playing with Spheres
Authors: MANTICA Giorgio
Published: November 2004

We show that a large class of circle packings can be generated by combining hyperbolic and spherical (or Euclidean) tessellation groups. We provide the general group-theoretical framework associated to an efficient, geometrically inspired, construction of these packings. We classify the different packings that can be obtained in this way, and we investigate their fractal properties.
PARALLEL COMPUTING AND ELECTRONIC-STRUCTURE THEORY
Authors: WILLIAMS A. R.
Published: November 2004

Parallel computing will become increasingly important in this decade. If combined with algorithms well suited to the exploitation of the medium granularity of the parallel computers available in the 90's, the utility of electronic structure calculations for both science and materials engineering could increase dramatically. This paper attempts to characterize the forces that will determine the type of computers available to us in this decade and presents an example of the type of algorithm which is well suited to such computers.
RECYCLE OF RANDOM SEQUENCES
Authors: ITO NOBUYASU , KIKUCHI MACOTO , OKABE YUTAKA
Published: November 2004

The correlation between a random sequence and its transformed sequences is studied. In the case of a permutation operation or, in other words, the shuffling operation, it is shown that the correlation can be so small that the sequences can be regarded as independent random sequences. The applications to the Monte Carlo simulations are also given. This method is especially useful in the Ising Monte Carlo simulation.
GLUEBALL AND MESON DISPERSION RELATIONS IN COMPACT U (1)2+1 LATTICE GAUGE THEORY
Authors: CHAARA A. M. , KROGER H. , MORIARTY K. J. M. , POTVIN J.
Published: November 2004

We have studied compact U (1) gauge theory in 2 + 1 dimensions in the framework of Hamiltonian lattice gauge theory, using a momentum [k] lattice. We consider glueball-like states and meson-like states. For the glueball states we compare the mass and the dispersion relation with results from a space-time lattice Hamiltonian method obtained by Irving et al. and with strong coupling perturbation theory results obtained by Hakim et al. and find good agreement. We introduce a compact momentum operator P on the lattice analogous to the compact Hamiltonian. The lattice Hamiltonian H and the lattice momentum P do not commute for finite lattice cutoff [a ≠ 0], which indicates violation of the Poincaré algebra. However, they commute for a → 0. We compute < P > for glueball and meson eigenstates. We obtain the dispersion relation E versus < P > and extract the mass, which agrees well with the mass obtained from E versus k.
THE SOFTWARE OF THE APE100 PROCESSOR
Authors: BARTOLONI A. , BASTIANELLO G. , BATTISTA C. , CABASINO S. , MARZANO F. , PAOLUCCI P. S. , PECH J. , RAPUANO F. , PANIZZI E. , SARNO R. , TODESCO G. M. , TORELLI M. , TROSS W. , VICINI P. , CABIBBO N. , TRIPICCIONE R.
Published: November 2004

We describe the software environment available for the APE100 parallel processor. We discuss the parallel programming language that we have defined for APE100 and its optimizing compiler. We then describe the operating system that allows to control APE100 from a host computer.
A NONLOCAL APPROACH TO VERTEX MODELS AND QUANTUM SPIN SYSTEMS
Authors: EVERTZ HANS GERD , MARCU MIHAI
Published: November 2004

We discuss the loop-algorithm, a new type of cluster algorithm that reduces critical slowing down in vertex models and in quantum spin systems. We cover the example of the 6-vertex model in detail. For the F-model, we present numerical results that demonstrate the effectiveness of the loop algorithm. We show how to modify the original algorithm for some more complicated situations, especially for quantum spin systems in one and two dimensions, and we discuss parallelization.
EMBEDDING MESH IN A LARGE FAMILY OF GRAPHS
Authors: HSU WEN-JING , PAGE CARL V.
Published: November 2004

It is well known that the nearest-neighbor connections of the mesh (especially the two-dimensional meshes) are very useful in parallel computations. Consequently, it is desirable to show that the graph representing the interconnection network of a parallel computer embeds the mesh. Most existing results of mesh-embedding are only applicable to a single kind of network. Here we demonstrate that a large family of interconnection networks called the generalized Fibonacci cubes all embed the mesh.
A PARALLEL ALGORITHM FOR FOREST RECONSTRUCTION
Authors: OLARIU STEPHAN , WEN ZHAOFANG
Published: November 2004

The purpose of this short note is to show that the problem of reconstructing a directed forest from a collection of leaf-to-root paths can be done efficiently in parallel by reducing the problem to integer sorting. Specifically, given M the total length of the paths in the collection, and n the number of distinct node labels, our algorithm reconstructs the corresponding forest (if such a forest exists) in O(M/p) time using p ≤ M/n processors or [Formula: see text] time using M/n < p < M processors, and O (M) space on the EREW-PRAM.
APPROXIMATING MAXIMUM 2-CNF SATISFIABILITY
Authors: HAGLIN DAVID J.
Published: November 2004

A parallel approximation algorithm for the MAXIMUM 2-CNF SATISFIABILITY problem is presented. This algorithm runs in O( log 2(n + |F|)) parallel time on a CREW PRAM machine using O(n + |F|) processors, where n is the number of variables and |F| is the number of clauses. Performance guarantees are considered for three slightly differing definitions of this problem.
CONVEX POLYGON PROBLEMS ON MESHES WITH MULTIPLE BROADCASTING
Authors: BHAGAVATHI D. , OLARIU S. , SCHWING J. L. , ZHANG J.
Published: November 2004

We propose time-optimal algorithms for a number of convex polygon problems on meshes with multiple broadcasting. Specifically, we show that on a mesh with multiple broadcasting of size n × n, the task of deciding whether an n-gon is convex, deciding whether two convex n-gons edge-intersect, deciding whether one convex n-gon lies in the interior of another, as well as variants of the tasks of computing the intersection and union of two convex n-gons can be accomplished in Θ( log n) time. We also show that detecting whether two convex n-gons are separable takes O(1) time.
CONSTRUCTING AN EXACT PARITY BASE IS IN RNC2
Authors: GALBIATI G. , MAFFIOLI F.
Published: November 2004

In this work we address the parallel complexity of two combinatorial problems, specifically the problems of the existence and of the construction of a parity base of preassigned weight (exact parity base for short) in a 0-1 weighted, represented matroid, subject to parity conditions. We prove that these problems lie in the parallel complexity class RNC 2, i.e. they are solvable with one-sided error by a logspace uniform family of bounded fan-in circuits of polynomial size and quadratic logarithmic depth which receive, in addition to the problem input, a polynomial number of random input bits. We also show that the more general cases of these problems, defined over matroids weighted with integral instead of 0-1 weights, also belong to RNC 2, as long as the weights are given in unary notation. As a consequence some special cases of these problems, which are of independent interest, belong to the same parallel complexity class: examples of these are the problem of the construction of a perfect matching of preassigned weight in a 0-1 weighted graph, recently addressed in [1], or that of the construction of a base of preassigned weight, in the intersection of two 0-1 weighted represented matroids.
MULTI-RATE ARRAYS AND AFFINE RECURRENCE EQUATIONS
Authors: LENDERS PATRICK M.
Published: November 2004

In this paper, we propose a general method for mapping Affine Recurrence Equations (ARE's) on a Multi-Rate Array (MRA). We show that the mapping is valid if and only if it maps the problem domain on the null space of the matrix (D − I) along the range space of this matrix (D is the dependency matrix, I is the identity matrix). We also prove that in the resulting array, variables are flowing at different speeds.
A PRACTICAL PLATFORM FOR CREW EMULATION
Authors: LOOGES PETER J. , OLARIU STEPHAN
Published: November 2004

The Parallel Random Access Machine or PRAM model, has been a much employed parallel algorithm development tool for a number of years. As such, many important problems have been solved on this model. Accordingly, considerable attention has been given to the process of simulating PRAM models on more realistic architectures. The purpose of this paper is to present an efficient simulation of the Concurrent Read Exclusive Write PRAM model by the crossbar connected machine (CCM). In addition to simulation, it is proven that all lower bounds for the CREW PRAM directly apply to the CCM. This is the first presentation of algorithmic lower bounds for a crossbar based model. The buses of the network are assumed to have a broadcast delay of δ(n). Recent implementations of the crossbar network in CMOS VLSI technology support the viability of the CCM model. It is the communication flexibility of the crossbar network which supports the PRAM simulations in a very straightforward manner without the complex interconnection systems or high overhead algorithms of many prior simulations.
A CONSTANT TIME ALGORITHM FOR REDUNDANCY ELIMINATION IN TASK GRAPHS ON PROCESSOR ARRAYS WITH RECONFIGURABLE BUS SYSTEMS
Authors: PRADEEP B. , MURTHY C. SIVA RAM
Published: November 2004

The task or precedence graph formalism is a practical tool to study algorithm parallelization. Redundancy in such task graphs gives rise to numerous avoidable inter-task dependencies which invariably complicates the process of parallelization. In this paper we present an O(1) time algorithm for the elimination of redundancy in such graphs on Processor Arrays with Reconfigurable Bus Systemusing O(n4) processors, The previous parallel algorithm available in the literature for redundancy elimination in task graphs takes O(n2) time using O(n) processors.
NOVEL PIPELINING AND PROCESSOR ALLOCATION STRATEGY FOR MONOID COMPUTATIONS ON UNSHUFFLE-EXCHANGE NETWORKS
Authors: CHUNG KUO-LIANG , CHANG HSUN-WEN
Published: November 2004

This short paper presents a novel pipelining and processor allocation strategy for monoid computations on an unshuffle-exchange network. In the strategy, the processor utilization is near 1 and the communication is collision-free. With the characteristics of constant connections to each processor and only a single output node on the network, the method given here can compete with the method of Barnard and Skillicorn based on a hypercube network with multiple output nodes.
DISTRIBUTED FAULT DIAGNOSIS OF A RING OF PROCESSORS
Authors: DAS A. , THULASIRAMAN K. , LAKSHMANAN K.B. , AGARWAL V.K.
Published: November 2004

Based on the theory of system level diagnosis pioneered by Preparata, Metze and Chien [1], we study fault diagnosis of a ring of processors. We use the comparison based model of Chwa and Hakimi [4]. It is shown that the processors in a ring can be diagnosed uniquely if, and only if, the faults are distributed in a certain manner. We present algorithms to diagnose the faulty processors when these requirements are satisfied. These algorithms permit distributed implementation on both unidirectional and bidirectional rings.
DATA PARALLEL VISUAL RECONSTRUCTION AND PARTITIONING ALGORITHMS
Authors: XIROUCHAKIS PAUL C. , WANG PEARL Y. , FRIEDER OPHIR
Published: November 2004

Data parallel visual reconstruction and partitioning algorithms and the associated code are developed for a vector random access machine (V-RAM). Finite element algorithms are constructed for solving the one-dimensional visual reconstruction problem with the input data consisting of a symmetrical top hat loading for the modeling of interacting step discontinuities. The advantage of the V-RAM implementation is the general code applicability to a variety of architectures. A specific implementation is performed on a Distributed Array Processor (DAP) simulator on the VAX 6000–420. Execution times on the DAP simulator are obtained and are found to be in agreement with the algorithmic complexities of the V-RAM code.
PARALLEL OBJECT REPRESENTATION AND RECOGNITION
Authors: WANG P.S.P.
Published: November 2004

A parallel method for 3-dimensional (3d) object recognition is introduced, using the concept of coordinated graph, layered graph representation, and parallel matching techniques, and significantly reduces the time required for dealing with 3-dimensional image analysis problems. Their fundamental parallel properties and concept of finite representations are investigated and several interested examples including curved and disconnected images are illustrated. In addition to its importance in theoretical parallel study, it can also be applied to 3-d parallel object recognition, image processing and computer vision.
BOUNDS FOR THE BANDWIDTH OF THE d-ARY DE BRUIJN GRAPH
Authors: PELLEGRINI FRANÇOIS
Published: November 2004

The computation of upper bounds of the bandwidth of graphs is mainly based on the giving of a numbering which achieves these bounds. In [9], Harper proposed such a numbering for the binary hypercube, based on the Hamming weights and binary values of the hypercube vertices.

By defining an extended Hamming weight, this numbering can lead to an equivalent proof for the d-ary de Bruijn graph. We present in this paper an approach, based on the use of the continuous domain and Laplace’s theorem for asymptotically evaluating integrals, which leads to the enumeration of the vertices of the same extended Hamming weight in the non-binary case. This result allows the computation of an upper bound of the bandwidth of the unoriented de Bruijn graph, as well as an upper bound of its vertex-bisection when both the diameter and the degree are even.
A UNIFIED APPROACH TO THE DESIGN AND CONTROL OF DYNAMIC MEMORY NETWORKS
Authors: FIOL M.A. , FÀBREGA J. , SERRA O. , YEBRA J.L.A.
Published: November 2004

A dynamic memory is a storage medium constituted by an array of cells and an interconnection network between them. It is characterized by the constant circulation of the stored data. The objective is to design the interconnection network in order to have small access times and a simple memory control. Several interconnection schemes have been proposed in the literature. This paper presents a quite general model for such structures that greatly facilitates both the design and the control of the memory. Most previous proposals of dynamic memory interconnection networks are particular instances of our model. Moreover, our approach is used to obtain new proposals of interconnection topologies for dynamic memories and fast cyclic shift registers. Namely, a model that optimizes both the access time and the size of the memory and two memory organizations for sequential access are presented.
LATENCY REDUCTION IN VLSI ROUTERS
Authors: JESSHOPE CHRIS
Published: November 2004

This paper presents recent results on the MP1 router chip designed to implement scalable parallel computers. We survey design considerations used in order to reduce message delivery latency to a minimum. Results will be presented of simulations of the MP1 network which back up these considerations. It will be shown that there are many degrees of freedom in implementation and that implementation issues will often overwhelm other considerations, those on which simulation is focused, leading to anomalous predictions from those results. An example will be given on this. Even ultra-low latency networks will still have access times to remote data which are 10 to 100 times that for access to local data and architectures which tolerate low latency data-access must be exploited if scalable performance is to be obtained in these parallel machines based on networks.
THE XOMEGA & THE OMEGA PYRAMIDS, A NEW FAMILY OF COMPETITIVE INTERCONNECTION NETWORKS
Authors: FIORINI PIERRE
Published: November 2004

A new family of interconnection networks, designed for massively parallel computers, is presented. Their main feature is a diameter smaller than the diameter of the hypercube up to networks of large sizes. As their degrees are fixed, they appear to be good challengers to other possible interconnection networks.
THE NARROW Θ5 PENTAQUARK AS THE FIRST NON-PLANAR HADRON WITH THE DIAMOND STRUCTURE AND NEGATIVE PARITY
Authors: SONG XING-CHANG , ZHU SHI-LIN
Published: November 2004

Using the picture of the flux tube model, we propose that the Θ5 pentaquark as the first candidate of the three-dimensional non-planar hadron with the extremely stable diamond structure. The up and down quarks lie at the corners of the diamond while the anti-strange quark sits in the center. Various un-excited color flux tubes between the five quarks bind them into a stable and narrow color-singlet. Such a configuration allows the lowest state having the negative parity naturally. The decay of the Θ5 pentaquark into the nucleon and kaon requires the breakup of the non-planar diamond configuration into two conventional planar hadrons, which involves some kind of structural phase transition as in the condensed matter physics. Hence the width of the Θ+ pentaquark should be narrow despite that it lies above the kaon nucleon threshold. We suggest that future lattice QCD calculation adopt non-planar interpolating currents to explore the underlying structure of the Θ5 pentaquark.
CPN−1 MODEL WITH A CHERN-SIMONS TERM
Authors: FERRETTI G. , RAJEEV S. G.
Published: November 2004

The CP N−1 model in three Euclidean dimensions is studied in the presence of a Chern-Simons term using the 1/N expansion. The β-function for the statistics parameter θ is found to be zero to order 1/N in the unbroken phase by an explicit calculation. It is argued to be zero to all orders. Some remarks on the θ dependence of the critical exponents are also made.
GENESIS AND EVOLUTION OF THE SKYRME MODEL FROM 1954 TO THE PRESENT
Authors: SANYUK VALERY I.
Published: November 2004

Not widely known facts on the genesis of the Skyrme model are presented in a historical survey, based on Skyrme's earliest papers and on his own published remembrance. We consider the evolution of Skyrme's model description of nuclear matter from the "Mesonic Fluid" model up to its final version, known as the baryon model. We pay special tribute to some well-known ideas in contemporary particle physics which one can find in Skyrme's earlier papers, such as: Nuclear Democracy, the Solitonic Mechanism, the Nonlinear Realization of Chiral Symmetry, Topological Charges, Fermi–Bose Transmutations, etc. It is curious to note in the final version of the Skyrme model gleams of Kelvin's "Vortex Atoms" theory. In conclusion we make a brief analysis of the validity of Skyrme's conjectures in view of recent results and pinpoint some questions which still remain.