bluuebunny/crossref_metadata_2025 huggingface dataset:
NUMERICAL METHODS FOR THE THREE-DIMENSIONAL TWO-BODY PROBLEM IN THE ACTION-AT-A-DISTANCE ELECTRODYNAMICS
Authors: NIKITIN I. N. , DE LUCA J.
Published: April 2003

We develop two numerical methods to solve the differential equations with deviating arguments for the motion of two charges in the action-at-a-distance electrodynamics. Our first method uses Stürmer's extrapolation formula and assumes that a step of integration can be taken as a step of light ladder, which limits its use to shallow energies. The second method is an improvement of pre-existing iterative schemes, designed for stronger convergence and can be used at high-energies.
INFLUENCE OF POINT DEFECTS ON THE SHEAR ELASTIC COEFFICIENTS AND ON THE MELTING TEMPERATURE OF COPPER
Authors: KANIGEL AMIT , ADLER JOAN , POLTURAK EMIL
Published: April 2003

We present molecular dynamics simulations of the influence of point defects on the shear elastic properties of copper. We find that vacancies do not influence these properties at all, while the introduction of interstitials causes a large reduction of the elastic coefficients. The simulations establish a phase diagram of the melting temperature as a function of the density of interstitials. A crystal having no free surface undergoes bulk mechanical melting as a result of the vanishing of C′ ≡ (C11 - C12)/2 once the specific volume reaches a critical value, equal to the experimental volume of liquid phase. This critical volume is history independent, in the sense that it does not depend on whether is it reached by heating the crystal or by adding defects at a constant temperature. These results generalize the Born model of melting for the case where point defects are present.
MOLECULAR-DYNAMICS SIMULATIONS OF CARBON NANOCAGE STRUCTURES: NANOBALLS AND NANOTOROIDS
Authors: ERKOÇ ŞAKIR , VURAL DERVIŞ CAN
Published: April 2003

The structural stability of carbon nanocages, fullerens and toroids, have been investigated by performing molecular-dynamics computer simulations. The systems considered are C 120 and C 240 in ball and toroidal structures. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that C 120 ball is very unstable, and the other structures are relatively more strong against heat treatment.
ON TELEGRAPH REACTION DIFFUSION AND COUPLED MAP LATTICE IN SOME BIOLOGICAL SYSTEMS
Authors: AHMED E. , ABDUSALAM H. A. , FAHMY E. S.
Published: April 2003

It is argued that telegraph equation is more suitable than ordinary diffusion equation in modeling reaction diffusion in biological, economic and social systems. Telegraph reaction diffusion (TRD) is studied in one and two spatial dimensions. Some exact and approximate results are obtained. A coupled map lattice (CML) corresponding to the spatial prisoner's dilemma game is constructed and studied in the weak diffusion limit. A formula is derived for Lyapunov exponents and it is shown that periodic solutions are dense in the weak coupling regime and that this system is structurally stable.
PATTERN RECOGNITION WITH HAMILTONIAN DYNAMICS
Authors: POTAPOV ALEXEI B. , ALI M. K.
Published: April 2003

We consider pattern recognition schemes that are based upon Hamiltonian dynamical system. Different oscillatory modes are used for storing and encoding patterns, and the effect of resonance is used for determining the most excited mode. We also propose a new technique for pattern orthogonalization resorting to hidden dimensions. Numerical experiments confirm high storage capacity and absence of false memories for the proposed system. Hamiltonian systems may be important as classical analogs of quantum computing systems or quantum neural networks.
THE KINEMATICS OF DISTRIBUTED COMPUTER TRANSACTIONS
Authors: BURGESS MARK
Published: April 2003

A causal, stochastic model of networked computers, based on information theory and nonequilibrium dynamical systems is presented. This provides a simple explanation for recent experimental results revealing the structure of information in network transactions. The model is based on non-Poissonian stochastic variables and pseudo-periodic functions. It explains the measured patterns seen in resource variables on computers in network communities. Weakly non-Poissonian behavior can be eliminated by a conformal scaling transformation and leads to a mapping onto statistical field theory. From this, it is possible to calculate the exact profile of the spectrum of fluctuations. This work has applications to anomaly detection and time-series analysis of computer transactions.
HANDS ON CERN - AN INTERNET EDUCATIONAL PROJECT IN PARTICLE PHYSICS
Authors: JOHANSSON K. E.
Published: April 2003

With the Hands on CERN project it is possible to "take part" in a modern particle physics experiment at the forefront of scientific research using scientific data transmitted via Internet. The primary aim is to show particle collisions from the physics frontline, to stimulate the interest in science and technology and to demonstrate the openness and international character of fundamental research. Hands on CERN complements the traditional physics education and confronts the students with contemporary physics and technology – both detector technology and data transmission technology via Internet - at its most fundamental level.
GLOBAL HIERARCHICALLY ADDRESSED NON-BROADCAST ETHERNET
Authors: SIDOROVS ANDRIS
Published: April 2003

A very important part of network building is LAN connectivity. It has also become a requirement to be able to isolate individual workgroups from each other. This paper tries to show an approach of hypothetical IP only global telecom implementation which would comply with the above mentioned prerequisite in an efficient manner.
TECHNOLOGICAL INNOVATION AND TEACHING METHODS: PROBLEMS AND PROSPECTS AT THE UNIVERSITY OF FLORENCE
Authors: RIBOLI MARIA CRISTINA
Published: April 2003

The wide diffusion of information technology brins generally changes in any field of society. In universities, the teaching approach must conform itself to these new needs adding the information technology tools into the learning process. A multi-disciplinary technical team of Florence University was set up a project involving technical staff developer, educational technologist and web developer and has pointed out issues concerning hardware, software, technical methods and knowledge required by these innovations.
THE DATAGRID PROJECT
Authors: RUGGIERI FEDERICO
Published: April 2003

An overview of the objectives and status of the DataGrid Project is presented, together with a brief introduction to the Grid metaphor and some references to the present Grid activities and initiatives related to DataGrid.
THE NOBEL E-MUSEUM – A MODERN SCIENCE EDUCATION PROJECT ON INTERNET
Authors: JOHANSSON ERIK
Published: April 2003

In the Nobel e-Museum project today's Internet technology is used to describe the astounding development of science via the Nobel prizes of the last hundred years. Animations and interactive environments are used to explore the scientific achievements that played an important role in the development of human knowledge and culture and are also used to demonstrate the role of scientific discoveries in today's society. The aim is also to inform about the achievements recognized by the Nobel Prizes and to stimulate the interest of students in the prize areas.
LECTURE OBJECT: AN ARCHITECTURE FOR ARCHIVING LECTURES ON THE WEB
Authors: VITAGLIONE GIOSUE , BOUSDIRA NORA , GOLDFARB STEVEN , NEAL HOMER A. , SEVERANCE CHARLES , STORR MICK
Published: April 2003

A new software architectural model for the archival of slide-based presentations on the Internet is proposed. This architecture is based on the concept of the "lecture object," a persistent format, independent of the lecture production and viewing technology. The work has been undertaken in the context of the Web Lecture Archive Project, a collaboration of the CERN HR Division Training and Development group and the University of Michigan, Ann Arbor. To date some 250 lectures have been archived and are viewable worldwide using standard Web browsers and freely available video player software.
ACTIVE MEASUREMENTS (EXPERIMENTS) OF THE INTERNET TRAFFIC USING CACHE-MESH
Authors: KRASHAKOV SERGEY A. , SHCHUR LEV N.
Published: April 2003

We present here the preliminary results of the active measurements of Internet traffic. The main goal is the measurement of the effectiveness of hierarchical cache developed last years in a number of countries using Squid software. The passive measurements could not give any conclusive answer. The procedure of the active measurements was developed for that reason. First, we use active measurements (experiments) of Internet traffic sending the http-requests from the log files. This give possibility to perform the comparative measurements which is usually more accurate. Next, more sophisticated procedure using triangle of cache servers, one working as the only manager for the two others, which could be setup differently and, typically, serve only odd and even queries respectively was proposed. This procedure, probably, is the most precise experimental setup for the comparative study of server strategies could be done on the basis of standard hardware and software.
AN ONLINE CLINICAL FOLDER APPLIED TO CHOROIDAL MELANOMA TREATMENT
Authors: MASCIALINO BARBARA , SQUARCIA SANDRO , MOSCI CARLO
Published: April 2003

An on-line clinical folder has been optimised in order to manage all the available data coming from eight years of choroidal melanoma treatment with proton beams. The system allows the ophthalmologist, in a very easy way, to record and update, in different display sessions, the required data coming from the usual eye specialised visit, the tumour determination and identification, all the radiotherapy treatment information and the clinical data derived from the post-treatment follow-up visits. The goal is a better patient cure coming from statistical data treatment. This field is of great interest in oncology because only with analytical correlation study among the irradiated dose to the tumour and the relevant parameters of the tumour itself, is possible to optimise the used treatment planning.
A HIGH-PERFORMANCE MIXED-TECHNOLOGY LAN FOR EDUCATION AND RESEARCH
Authors: ARLANDINI CLAUDIO D. , BOSCHINI MATTEO J. , MATTASOGLIO ANDREA
Published: April 2003

In this work we describe a series of performance tests on different architectures of high bandwidth local area networks, contemporarily in use at C.I.L.E.A. (Inter-University Consortium for Automatic Elaboration of Lombardy) to connect multi-processor machines devoted to educational and research purposes, such as fluido-dynamic and mechanical simulations. This LAN is essentially made out of a standard FDDI ring, and an HyperFabric backbone. HyperFabric is a Hewlett-Packard high performance network system bus, with a declared maximum bandwidth of 2.5 Gbit/s full duplex per link. We present a comparison, in terms of effective bandwidth, average throughput and CPU consumption of the above mentioned network systems. Furthermore we also describe the effects, in terms of transfer efficiency, of such a mixed environment, in which different systems co-exist and must often be cross-walked by various applications, as backups and mass storage access. Measurements and comparisons are made using Open Software tools like netperf and HetPIPE.
VIRTUAL REALITY AND SCIENTIFIC VISUALIZATION: WORKING WITH MODELS AND HYPOTHESES
Authors: BARCELÓ JUAN A.
Published: April 2003

In this paper, a general framework is presented for using Virtual Reality Techniques in the domain of Scientific Visualization. It is argued that "visualizing" it is not the same as "seeing", but an inferential process to understand reality. A definition of Enhanced Reality is also presented, and how visual models can be used in order to obtain additional information about the dynamic nature of natural and social phenomena.
USING THE NETWORK FOR EDUCATION AND OUTREACH IN ASTRONOMY
Authors: BENACCHIO LEOPOLDO
Published: April 2003

This paper is divided into two parts. In the first the project of didactics and outreach "Catch the Stars in the Net!" is described, while in the second one an account of some important lessons learned on the way the Network use change the rules of the play is given. An account of the new Web module: "The Universe at Your fingertips", especially developed for visually impaired and even completely blind Web users in finally given.
EMCORE – EMOTIONAL COOPERATIVE GROUPWARE: A GROUPWARE TOOL FOR COLLABORATIVE WORK
Authors: FASOLI N. , MESSINA A.
Published: April 2003

In the last years considerable effort has been spent to develop groupware applications. Despite this, no general consenus has been met by groupware applications in computer field. Interdisciplinary approach could prove very useful to overcome these difficulties. A workgroup is not simply a set of people gathered together, working for a common goal. It can also be thought as a strong, hard mental reality. Actually, sociological and psychological definitions of group differ considerably. At sociological level a group is generally described in the view of the activities and events occurring inside the group itself. On the other hand, the psychological group approach considers not only the actions occurring inside the group, but also all the mental activities originated by belonging to the group, be they emotional or rational nature. Since early '60 simple work group (i.e. discussion group) has been analyzed in his psychological behavior. EMCORE is a prototype which aims to support computer science methods with psychological approach. The tool has been developed for a discussion group supported by heterogeneous distributed systems and has been implemented according to the CORBA abstraction augmented by the machine independent JAVA language. The tool allows all the common activities of a discussion group: discussion by voice or by chatting board if multimedia device are not present; discussion and elaboration of a shared document by text and/or graphic editor. At the same time, tools are provided for the psychoanalytic approach, according to a specific methodology.
AFRICAN VIRTUAL UNIVERSITY - IRELAND'S INVOLVEMENT
Authors: KAVANAGH BOB
Published: April 2003

The background to the African Virtual University and Ireland's participation in it and in the initial project are described.
A NEW ALGORITHM FOR DYNAMIC PROGRAMMING ON REGULAR ARRAYS
Authors: DJAMEGNI CLÉMENTIN TAYOU , TCHUENTE MAURICE
Published: April 2003

Given the real entries w(i, j), 1≤ i < j ≤n, and c(i, i+1), 1≤ i< n, the dynamic programming problem studied here consists of computing the coefficients c ( i , j )= w ( i , j ) + min i < k < j { c ( i , k )+ c ( k , j )}, for 1≤ i< j≤n. We show that this problem can be solved in optimal time T*=2n-1 on a regular array of size n 2/10+ O ( n ). The number of processors required by this new algorithm improves the best previously known bound n 2/10+ O ( n ). The idea introduced here is to apply to the dependence graph associated with the problem a pre-processing that removes long-range communications in order to obtain a new locally connected graph which is suitable for the application of powerful allocation techniques.
A WORMHOLE ROUTER WITH EMBEDDED BROADCASTING VIRTUAL BUS FOR MESH COMPUTERS
Authors: KIM BONG WAN , CHOI JONG HYUK , PARK KWANG-IL , PARK KYU HO
Published: April 2003

In this paper, we propose a new method of implementing bus operations on mesh wormhole routers with small additional circuits. The bus, called a virtual bus, is set up dynamically upon a request by bypassing existing datapath in wormhole routers. After bus setup, it acts as a real bus by sharing the point-to-point links of the corresponding row/column of the mesh. Simulation results show that the 2D (two-dimensional) mesh with the virtual bus outperforms the mesh with separate buses.
TIGHTER TIME BOUNDS ON BROADCASTING IN TORUS NETWORKS IN PRESENCE OF DYNAMIC FAULTS
Authors: DE MARCO GIANLUCA , RESCIGNO ADELE A.
Published: April 2003

We consider the problem of broadcasting in a network G under the hypothesis that each vertex can inform in one unit of time all of its neighbours and that any number of message transmissions, less than the edge-connectivity of G, may fail during each time unit. In particular, we study broadcasting in the n-dimensional k-ary torus, a popular topology for link connections in communication networks. We prove that under the above strong fault-assumption, if k is even and polynomially limited in n, and n is sufficient large, broadcasting in the n-dimensional k-ary torus can be accomplished in time [Formula: see text], where [Formula: see text] is the diameter of the n-dimensional k-ary torus.
NC ALGORITHMS FOR THE SINGLE MOST VITAL EDGE PROBLEM WITH RESPECT TO ALL PAIRS SHORTEST PATHS
Authors: VENEMA SVEN , SHEN HONG , SURAWEERA FRANCIS
Published: April 2003

For a weighted, undirected graph G=(V, E) where |V|=n and |E|=m, we examine the single most vital edge with respect to all-pairs shortest paths (APSP) under two different measurements. The first measurement considers only the impact of the removal of a single edge from the APSP on the shortest distance between each vertex pair. The second considers the total weight of all the edges which make up the APSP, that is, calculate the sum of the distance between each vertex pair after the deletion of any edge belonging to a shortest path. We give a sequential algorithm for this problem, and show how to obtain an NC algorithm running in O( log n) time using mn2 processors and O(mn2) space on the MINIMUM CRCW PRAM. Given the shortest distance between each pair of vertices u and v, the diameter of the graph is defined as the longest of these distances. The Most vital edge with respect to the diameter is the edge lying on such a u–v shortest path which when removed causes the greatest increase in the diameter. We show how to modify the above algorithm to solve this problem using the same time and number of processors. Both algorithms compare favourably with the straightforward solution which simply recalculates the all pairs shortest path information.
AN ANALYTICAL METHOD FOR PARALLELIZATION OF RECURSIVE FUNCTIONS
Authors: AHN JOONSEON , HAN TAISOOK
Published: April 2003

Programming with parallel skeletons is an attractive framework because it encourages programmers to develop efficient and portable parallel programs. However, extracting parallelism from sequential specifications and constructing efficient parallel programs using the skeletons are still difficult tasks.

In this paper, we propose an analytical approach to transforming recursive functions on general recursive data structures into compositions of parallel skeletons. Using static slicing, we have defined a classification of subexpressions based on their data-parallelism. Then, skeleton-based parallel programs are generated from the classification. To extend the scope of parallelization, we have adopted more general parallel skeletons which do not require the associativity of argument functions. In this way, our analytical method can parallelize recursive functions with complex data flows.
Algorithmic Complexity with Page-Based Intelligent Memory
Authors: Oskin Mark , Lita Lucian-Vlad , Chong Frederic T. , Hensley Justin , Keen Diana
Published: April 2003

High DRAM densities will make intelligent memory chips a commodity in the next five years [1] [2]. This paper focuses upon a promising model of computation in intelligent memory, Active Pages [3], where computation is associated with each page of memory. Computational hardware scales linearly and inexpensively with data size in this model, reducing the order of many algorithms. This scaling can, for example, reduce linear-time algorithms to [Formula: see text]. When page-based intelligent memory chips become available in commodity, they will change the way programmers select and utilize algorithms.

In this paper, we analyze the asymptotic performance of several common algorithms as problem sizes scale. We also derive the optimal page size, as a function of problem size, for each algorithm running with intelligent memory. Finally, we validate these analyses with simulation results.
LOCALITY-PRESERVING LOAD-BALANCING MECHANISMS FOR SYNCHRONOUS SIMULATIONS ON SHARED-MEMORY MULTIPROCESSORS
Authors: VEE VOON-YEE , HSU WEN-JING
Published: April 2003

In the past decade, many synchronous algorithms have been proposed for parallel and discrete simulations. However, the actual performance of these algorithms have been far from ideal, especially when event granularity is small. Barring the case of low parallelism in the given simulation models, one of the main reasons of low speedups is in the uneven load distribution among processors. To amend for this, both static and dynamic load balancing approaches have been proposed. Nevertheless, static schemes based on partitioning of LPs are often subject to the dynamic behavior of the specific simulation models and are therefore application dependent; dynamic load balancing schemes, on the other hand, often suffer from loss of localities and hence cache misses, which could severely penalize on fine-grained event processing. In this paper, we present several new locality-preserving load balancing mechanisms for synchronous simulations on shared-memory multiprocessors. We focus on the type of synchronous simulations where the number of LPs to be processed within a cycle decreases monotonically. We show both theoretically and empirically that some of these mechanisms incur very low overhead. The mechanisms have been implemented by using MIT's Cilk and tested with a number of simulation applications. The results confirm that one of the new mechanisms is indeed more efficient and scalable than common existing approaches.
AN EFFICIENT INCREMENTAL ALGORITHM FOR GENERATING ALL MAXIMAL INDEPENDENT SETS IN HYPERGRAPHS OF BOUNDED DIMENSION
Authors: BOROS E. , GURVICH V. , ELBASSIONI K. , KHACHIYAN L.
Published: April 2003

We show that for hypergraphs of bounded edge size, the problem of extending a given list of maximal independent sets is NC-reducible to the computation of an arbitrary maximal independent set for an induced sub-hypergraph. The latter problem is known to be in RNC. In particular, our reduction yields an incremental RNC dualization algorithm for hypergraphs of bounded edge size, a problem previously known to be solvable in polynomial incremental time. We also give a similar parallel algorithm for the dualization problem on the product of arbitrary lattices which have a bounded number of immediate predecessors for each element.
SCHEDULING COMPLETE TREES ON TWO UNIFORM PROCESSORS WITH INTEGER SPEED RATIOS AND COMMUNICATION DELAYS
Authors: BLAZEWICZ J. , GUINAND F. , PENZ B. , TRYSTRAM D.
Published: April 2003

In this paper, we present an algorithm that builds optimal schedules for complete in-trees on two uniform processors, with arbitrary integer speed ratios, in the presence of communication delays.
ON FINDING A HAMILTONIAN PATH IN A TOURNAMENT USING SEMI-HEAP
Authors: WU JIE
Published: April 2003

The problem of sorting an intransitive total ordered set, a generalization of regular sorting, is considered. This generalized sorting is based on the fact that there exists a special linear ordering (also called a generalized sorted sequence) for any intransitive total ordered set, or equivalently, the existence of a Hamiltonian path in a tournament. A new data structure called semi-heap is proposed to construct an optimal Θ(n log n) sorting algorithm. We also provide a cost-optimal parallel algorithm using semi-heap. The run time of this algorithm is Θ(n) with Θ( log n) processors under the EREW PRAM model. The use of a Hamiltonian path (generalized sorting sequence) as an approximation of a ranking system in a tournament is also discussed.
WORMHOLE DEADLOCK PREDICTION
Authors: DI IANNI MIRIAM
Published: April 2003

Deadlock prevention is usually realized by forbidding transmissions that could eventually cause a deadlock to occur. However, an optimal routing algorithm with respect to channel utilization forbids transmissions only when they would bring the network into a configuration that will necessarily evolve into a deadlock. Hence, optimal deadlock prevention is closely related to deadlock prediction. In this paper it is shown that wormhole deadlock and livelock prediction is a hard problem for both oblivious and adaptive routing.
DEADLOCK-FREE FAULT-TOLERANT MULTICAST ROUTING IN HYPERCUBES
Authors: SENGUPTA ABHIJIT , VISWANATHAN SURESH
Published: April 2003

In this paper, an algorithm is presented to embedd a ring in an n-dimensional hypercube with at most n-1 faults; subsequently, the embedded ring is used for efficient deadlock-free multicast routing between all the fault-free nodes. Simulation results are presented to compare the performance of the algorithm to that of the routing algorithm proposed in [9] for a fault-free hypercube to study the performance degradation because of faults. A modification to the algorithm of [9] is also presented for improved performance.
FAULTY RANDOM GEOMETRIC NETWORKS
Authors: DIAZ JOSEP , PETIT JORDI , SERNA MARIA
Published: April 2003

In this paper we analyze the computational power of random geometric networks in the presence of random (edge or node) faults considering several important network parameters. We first analyze how to emulate an original random geometric network G on a faulty network F. Our results state that, under the presence of some natural assumptions, random geometric networks can tolerate a constant node failure probability with a constant slowdown. In the case of constant edge failure probability the slowdown is an arbitrarily small constant times the logarithm of the graph order. Then we consider several network measures, stated as linear layout problems (Bisection, Minimum Linear Arrangement and Minimum Cut Width). Our results show that random geometric networks can tolerate a constant edge (or node) failure probability while maintaining the order of magnitude of the measures considered here. Finally we show that, with high probability, random geometric networks with (edge or node) faults do have a Hamiltonian cycle, provided the failure probability is constant. Such capability enables performing distributed computations based on end-to-end communication protocols.
MPI-FT: PORTABLE FAULT TOLERANCE SCHEME FOR MPI
Authors: LOUCA SOULLA , NEOPHYTOU NEOPHYTOS , LACHANAS ADRIANOS , EVRIPIDOU PARASKEVAS
Published: April 2003

In this paper, we propose the design and development of a fault tolerant and recovery scheme for the Message Passing Interface (MPI). The proposed scheme consists of a detection mechanism for detecting process failures, and a recovery mechanism. Two different cases are considered, both assuming the existence of a monitoring process, the Observer which triggers the recovery procedure in case of failure. In the first case, each process keeps a buffer with its own message traffic to be used in case of failure, while the implementor uses periodical tests for notification of failure by the Observer. The recovery function simulates all the communication of the processes with the dead one by re-sending to the replacement process all the messages destined for the dead one. In the second case, the Observer receives and stores all message traffic, and sends to the replacement all the buffered messages destined for the dead process. Solutions are provided to the dead communicator problem caused by the death of a process. A description of the prototype developed is provided along with the results of the experiments performed for efficiency and performance.
CELLULAR GRAVITY
Authors: GRUAU FRÉDÉRIC , TROMP JOHN
Published: April 2003

We consider the problem of establishing gravity in cellular automata. In particular, when cellular automata states can be partitioned into empty, particle, and wall types, with the latter enclosing rectangular areas, we desire rules that will make the particles fall down and pile up on the bottom of each such area. We desire the rules to be both simple and time-efficient. We propose a block rule, and prove that it piles up particles on a grid of height h in time at most 3*h.
TAGGED-TOKEN DATA-FLOW FOR SKELETONS
Authors: SEROT JOCELYN
Published: April 2003

This paper discusses the use of a tagged-token macro data-flow execution model for implementing skeletons within the SKIPPER parallel programming environment. We show that it provides a suitable implementation model for skeletons involving runtime-bounded iterations and/or recursion such as data and task farms, especially in the presence of nesting. The new version of SKIPPER relies on a custom data-flow interpreter controlling SPMD based parallelism. Input data-flow graphs are obtained from a skeletal program specification written in CAML and making use of user defined sequential functions written in C. Initial evaluation suggests that performance close to handcrafted C with MPI can be achieved and that the support for nesting does not entail a significant performance penalty.
SKELETONS, BSP AND PERFORMANCE PORTABILITY
Authors: ZAVANELLA ANDREA
Published: April 2003

The Skeletal approach to parallel programming conjugates a high-level compositional style and efficiency. A second advantage of Skeletal programming is portability since implementation decisions are usually taken at compile time. The paper claims that an intermediate model embedding the main performance features of the target architecture facilitates performance portability across parallel architectures. This is motivated by describing the Skel-BSP framework which implements a skeleton system on top of a BSP computer. A prototype compiler based on a set of BSP templates is presented together with a set of performance models for each skeleton which allow a local optimization. The paper also introduces a global optimization strategy using a set of transformation rules. This local+global approach seems a viable solution to writing parallel software in machine-independent way (Writing Once and Compiling Everywhere).
A NEW WAY TO DIVIDE AND CONQUER
Authors: TISKIN ALEXANDRE
Published: April 2003

Valiant's model of bulk-synchronous parallel (BSP) computation does not allow the programmer to synchronize a subset, rather than the complete set of a parallel computer's processors. This is perceived by many to be an obstacle to expressing divide-and-conquer algorithms in the BSP model. We argue that the divide-and-conquer paradigm fits naturally into the BSP model, without any need for subset synchronization. The proposed method of divide-and-conquer BSP programming is fully compliant with the BSP computation model. The method is based on sequentially interleaved threads of BSP computation, called superthreads.
DISTRIBUTED EVALUATION OF FUNCTIONAL BSP PROGRAMS
Authors: LOULERGUE F.
Published: April 2003

The BS λp-calculus is a calculus of functional bulk synchronous parallel (BSP) programs. It is the basis for the design of a bulk synchronous parallel ML language. For data-parallel languages, there are two points of view: the programming model where a program is seen as a sequence of operations on parallel vectors, and the execution model where the program is a parallel composition of programs run on each processor of the parallel machine. BSP algorithms are defined by data-parallel algorithms with explicit (physical) processes in order to allow their parallel execution time to be estimated. We present here a distributed evaluation minimally synchronous for BSP execution (which corresponds to the execution model). This distributed evaluation is correct w.r.t. the call-by-value strategy of the BS λp-calculus (which corresponds to the programming model).
THEMIS: COMPONENT DEPENDENCE METADATA IN ADAPTIVE PARALLEL APPLICATIONS
Authors: KELLY PAUL H. J. , BECKMANN OLAV , FIELD TONY , BADEN SCOTT B.
Published: April 2003

This paper describes THEMIS, a programming model and run-time library being designed to support cross-component performance optimization through explicit manipulation of the computation's iteration space at run-time.

Each component is augmented with "component dependence metadata", which characterizes the constraints on its execution order, data distribution and memory access order. We show how this supports dynamic adaptation of each component to exploit the available resources, the context in which its operands are generated, and results are used, and the evolution of the problem instance.

Using a computational fluid dynamics visualization example as motivation, we show how component dependence metadata provides a framework in which a number of interesting optimizations become possible. Examples include data placement optimization, loop fusion, tiling, memoization, checkpointing and incrementalization.
SHARED MEMORY IMPLEMENTATION OF CONSTRAINT SATISFACTION PROBLEM RESOLUTION
Authors: HABBAS ZINEB , KRAJECKI MICHAËL , SINGER DANIEL
Published: April 2003

Many problems in Computer Science, especially in Artificial Intelligence, can be formulated as Constraint Satisfaction Problems (CSP). This paper presents a parallel implementation of the Forward-Checking algorithm for solving a binary CSP over finite domains. Its main contribution is to use a simple decomposition strategy in order to distribute dynamically the search tree among machines. The feasibility and benefit of this approach are studied for a Shared Memory model. An implementation is drafted using the new emergent standard OpenMP library for shared memory, thus controlling load balancing. We mainly highlight satisfactory efficiencies without using any tricky load balancing policy. All the experiments were carried out running on the Sillicon Graphics Origin 2000 parallel machine.
INDIRECT CONSTRAINTS ON THE TRIPLE GAUGE BOSON COUPLINGS FROM $\bm{Z\to b{\bar b}}$ PARTIAL WIDTH: AN UPDATE
Authors: ÉBOLI O. J. P. , GONZALEZ-GARCIA M. C. , NOVAES S. F.
Published: April 2003

We update the indirect bounds on anomalous triple gauge couplings coming from the non-universal one-loop contributions to the [Formula: see text] width. These bounds, which are independent of the Higgs boson mass, are in agreement with the standard model predictions for the gauge boson self-couplings since the present value of Rb agrees fairly well with the theoretical estimates. Moreover, these indirect constraints on [Formula: see text] and [Formula: see text] are most stringent than the present direct bounds on these quantities, while the indirect limit on λZ is weaker than the available experimental data.
γγ TOTAL CROSS-SECTION AT HIGH ENERGIES
Authors: BOURRELY C. , SOFFER J. , WU TAI TSUN
Published: April 2003

We show that the rising total cross-sections σ(γγ→ hadrons) recently observed by the L3 and OPAL collaborations at LEP are fully consistent with the impact-picture for high-energy scattering. The impact picture is then used to predict this γγ total cross-section at higher energies, and confirm the universal increase of total cross-sections including those of pp, [Formula: see text] and γp.
NEUTRINO MASSES AND MIXINGS IN SO(10)M
Authors: ABUD M. , BUCCELLA F. , TRAMONTANO F. , FALCONE D. , RICCIARDI G.
Published: April 2003

Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the seesaw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for Ue3 and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in an SO (10)M model with Pati–Salam SU (4)× SU (2)× SU (2) intermediate symmetry.
PHOTOPRODUCTION OF DILATONS IN AN EXTERNAL MAGNETIC FIELD
Authors: SOA DANG VAN , LONG HOANG NGOC
Published: April 2003

An attempt is made to present some experimental predictions of the five dimensions Kaluza–Klein theory. The conversion of photons into dilatons in the static magnetic fields are considered in detail. The differential cross-sections are presented for the conversions in a magnetic field of the flat condensor and a magnetic field of the solenoid. A numerical evaluation shows that in the present technical scenario, the creation of dilatons at high energies may have the observable value.
ON FERMION MASS HIERARCHY WITH EXTRA DIMENSIONS
Authors: YOSHIOKA KOICHI
Published: April 2003

Recently, various phenomenological implications of the existence of extra space–time dimensions have been investigated. In this letter, we construct a model with realistic fermion mass hierarchy with (large) extra dimensions beyond the usual four dimensions. In this model, it is assumed that some matter fields live in the bulk and the others are confined to our four-dimensional wall. It can naturally reproduce the quark and lepton mass hierarchy and mixing angles without any symmetry arguments. We also discuss some possibilities of obtaining suitable neutrino masses and mixings for the solar and atmospheric neutrino problems.
CONSTRAINTS ON GALAXY EVOLUTION THROUGH GRAVITATIONAL LENSING STATISTICS
Authors: JAIN DEEPAK , PANCHAPAKESAN N. , MAHAJAN S. , BHATIA V. B.
Published: April 2003

Explaining the formation and evolution of galaxies is one of the most challenging problems in observational cosmology. Many observations suggest that galaxies we see today could have evolved from the merging of smaller subsystems. Evolution of galaxies tells us how the mass or number density of the lens varies with cosmic time. Merging between the galaxies and the infall of surrounding mass into galaxies are two possible processes that can change the comoving number density of galaxies and/or their mass. We consider five different evolutionary models of galaxies. These models are: Non-evolutionary model, Guiderdoni and Volmerange model, fast merging, slow merging and mass accretion model. We study the gravitational lens image separation distribution function for these models of evolving galaxies. A comparison with data for lensed quasars taken from the HST snapshot survey rules out the fast merging model completely as this model produces a large number of small-separation lenses. It is possible that the mass accretion model and the non-evolutionary model of galaxies may be able to explain the small angle separations.
SYMMETRIES OF SU(2) SKYRMION IN HAMILTONIAN AND LAGRANGIAN APPROACHES
Authors: HONG SOON-TAE , KIM YONG-WAN , PARK YOUNG-JAI
Published: April 2003

We apply the Batalin–Fradkin–Tyutin (BFT) method to the SU (2) Skyrmion to study the full symmetry structure of the model at the first-class Hamiltonian level. On the other hand, we also analyze the symmetry structure of the action having the WZ term, which corresponds to this Hamiltonian, in the framework of the Lagrangian approach. Furthermore, following the BFV formalism we derive the BRST invariant gauge fixed Lagrangian from the above extended action.
CLASSICAL AND QUANTUM COMPARISON OF KINK AND BELL SOLITONS AS ZERO-BRANES
Authors: ZLOSHCHASTIEV KONSTANTIN G.
Published: April 2003

The self-interacting scalar field theory with the negative coupling constant gives rise to the bell-shaped solitary wave solution which can be interpreted as a massive Bose particle. We compare its properties with those of the kink solution (also known as the domain-wall potential) arisen in the theory with the positive constant introducing the simplest example of the spontaneous breaking of symmetry. We rule out the uniform p-brane action for the kink and bell solutions as the nonminimal point particles with curvature. When quantizing it as the theory with higher derivatives, it is shown that the appearing quantum equation has SU (2) dynamical symmetry group realizing the exact spin-coordinate correspondence. Finally, we calculate the quantum corrections to the masses of kink and bell bosons which cannot be obtained by means of the perturbation theory starting from the vacuum sector.
QUASICLASSICAL ANALYSIS OF THREE-DIMENSIONAL SCHRÖDINGER'S EQUATION AND ITS SOLUTION
Authors: SERGEENKO M. N.
Published: April 2003

Three-dimensional Schrödinger's equation is analyzed with the help of the correspondence principle between classical and quantum-mechanical quantities. Separation is performed after reduction of the original equation to the form of the classical Hamilton–Jacobi equation. Each one-dimensional equation obtained after separation is solved by the conventional WKB method. Quasiclassical solution of the angular equation results in the integral of motion [Formula: see text] and the existence of nontrivial solution for the angular quantum number l = 0. Generalization of the WKB method for multi-turning-point problems is given. Exact eigenvalues for solvable and some "insoluble" spherically symmetric potentials are obtained. Quasiclassical eigenfunctions are written in terms of elementary functions in the form of a standing wave.
COMPLETION OF THE CONJECTURE: QUANTUM COHOMOLOGY OF FANO HYPERSURFACES
Authors: JINZENJI MASAO
Published: April 2003

In this letter, we propose the formulas that compute all the rational structural constants of the quantum Kähler subring of Fano hypersurfaces.
ON THE EQUIVALENCE BETWEEN TOPOLOGICALLY AND NON-TOPOLOGICALLY MASSIVE ABELIAN GAUGE THEORIES
Authors: HARIKUMAR E. , SIVAKUMAR M.
Published: April 2003

We analyze the equivalence between topologically massive gauge theory (TMGT) and different formulations of non-topologically massive gauge theories (NTMGTs) in the canonical approach. The different NTMGTs studied are Stückelberg formulation of (a) a first-order formulation involving one- and two-form fields, (b) Proca theory, and (c) massive Kalb–Ramond theory. We first quantize these reducible gauge systems by using the phase space extension procedure and using it, identify the phase space variables of NTMGTs which are equivalent to the canonical variables of TMGT and show that under this the Hamiltonian also get mapped. Interestingly it is found that the different NTMGTs are equivalent to different formulations of TMGTs which differ only by a total divergence term. We also provide covariant mappings between the fields in TMGT to NTMGTs at the level of correlation function.
BETHE ANSATZ SOLUTION OF THE CLOSED ANISOTROPIC SUPERSYMMETRIC U MODEL WITH QUANTUM SUPERSYMMETRY
Authors: HIBBERD KATRINA , RODITI ITZHAK , LINKS JON , FOERSTER ANGELA
Published: April 2003

The nested algebraic Bethe Ansatz is presented for the anisotropic supersymmetric U> model maintaining quantum supersymmetry. The Bethe Ansatz equations of the model are obtained on a one-dimensional closed lattice and an expression for the energy is given.
(SUPER)n-ENERGY FOR ARBITRARY FIELDS AND ITS INTERCHANGE: CONSERVED QUANTITIES
Authors: SENOVILLA JOSÉ M. M.
Published: April 2003

Inspired by classical work of Bel and Robinson, a natural purely algebraic construction of super-energy (s-e) tensors for arbitrary fields is presented, having good mathematical and physical properties.

Remarkably, there appear quantities with mathematical characteristics of energy densities satisfying the dominant property, which provides s-e estimates useful for global results and helpful in other matters.

For physical fields, higher order (super)n-energy tensors involving the field and its derivatives arise. In special relativity, they provide infinitely many conserved quantities.

The interchange of s-e between different fields is shown. The discontinuity propagation law in Einstein–Maxwell fields is related to s-e tensors, providing quantities conserved along null hypersurfaces. Finally, conserved s-e currents are found for any minimally coupled scalar field whenever there is a Killing vector.
DETERMINING THE PARAMETERS OF ηη′ MIXING IN THE FRAMEWORK OF ANOMALOUS WARD IDENTITIES
Authors: BAGCHI B. , BHATTACHARYYA P.
Published: April 2003

The solutions of anomalous Ward identities are used to determine the ηη′ mixing parameters θ8 and θ0 and the octet–singlet decay constants f8 and f0 in a U (3) × U (3) framework. Our results are fairly consistent with other recent findings for these quantities. We also enquire into the quark-flavor mixing scheme and obtain estimates for the corresponding decay constants defined in this basis.
TOPOLOGICAL SYMMETRIES
Authors: MOSTAFAZADEH A. , SAMANI K. AGHABABAEI
Published: April 2003

We introduce the notion of a topological symmetry as a quantum mechanical symmetry involving a certain topological invariant. We obtain the underlying algebraic structure of the ℤ2-graded uniform topological symmetries of types (1, 1) and (2, 1). This leads to a novel derivation of the algebras of supersymmetry and p = 2 parasupersymmetry.
SEPARATING DIFFERENT MODELS FROM MEASURING α, β, γ
Authors: ZHOU Y. F. , WU Y. L.
Published: April 2003

New physics effects on the [Formula: see text] mixing and B-decay amplitudes are discussed. By a combined analysis, the models of new physics can be partially distinguished. It is emphasized that the extraction of unitarity angles β and γ through rare decay [Formula: see text] and charged B decay B± → DK± respectively is not likely to be affected by new physics. Such an observation could be used to distinguish the new physics effects from different models. For instance, the top quark two-Higgs doublet model can be easily separated from those models without new phase in B-decay amplitudes, and can be further distinguished from the most general two-Higgs doublet model by its absence of new phase in the [Formula: see text] mixing.
GRAND UNIFICATION USING A GENERALIZED YANG–MILLS THEORY
Authors: CHAVES M. , MORALES H.
Published: April 2003

Generalized Yang–Mills theories have a covariant derivative that employs both scalar and vector bosons. Here we show how grand unified theories of the electroweak and strong interactions can be constructed with them. In particular the SU (5) GUT can be obtained from SU (6) with SU (5)× U (1) as a maximal subgroup. The choice of maximal subgroup also determines the chiral structure of the theory. The resulting Lagrangian has only two terms, and only two irreducible representations are needed, one for fermions and another for bosons.
ON ELECTROWEAK BARYOGENESIS IN GAUGE MEDIATED MODELS WITH MESSENGER–MATTER MIXING
Authors: GORBUNOV D. S.
Published: April 2003

We consider feasibility of electroweak baryogenesis in gauge mediated supersymmetry breaking models with messenger–matter mixing. We present a class of models where electroweak baryogenesis produces sufficient amount of baryon asymmetry. The main features of these models are (i) large mixing between messengers and right stop and (ii) fairly narrow region of viable tan β.
ON THE q-DEFORMATION OF THE NJL MODEL
Authors: TIMÓTEO V. S. , LIMA C. L.
Published: April 2003

Using a q-deformed fermionic algebra we perform explicitly a deformation of the Nambu–Jona-Lasinio (NJL) Hamiltonian. In the Bogoliubov–Valatin approach we obtain the deformed version of the functional for the total energy, which is minimized to obtain the corresponding gap equation. The breaking of chiral symmetry and its restoration in the limit q → 0 are then discussed.
A STUDY OF GLUON PROPAGATOR ON COARSE LATTICE
Authors: MA J. P.
Published: April 2003

We study gluon propagator in Landau gauge with lattice QCD, where we use an improved lattice action. The calculation of gluon propagator is performed on lattices with the lattice spacing from 0.40 fm to 0.24 fm and with the lattice volume from (2.40 fm )4 to (4.0 fm )4. We find that the rotation invariance is approximately restored in the q2-range, indicated by the fact that the propagator is a smooth function of the continuum momentum q2. We try to fit our results by two different ways, in the first one we interpret the calculated gluon propagators as a function of the continuum momentum, while in the second we interpret the propagators as a function of the lattice momentum. In both cases we use models which are the same in continuum limit. A qualitative agreement between two fittings is found.
GREEN'S FUNCTIONS IN AXIAL- AND LORENTZ-TYPE GAUGES AND BRS TRANSFORMATIONS
Authors: JOGLEKAR SATISH D.
Published: April 2003

A formula that relates the Green functions in axial-type gauges and Lorentz type gauges is established in a simpler manner. This result sheds further light on some of our earlier results using field transformations (a finite field-dependent BRS transformation) that relates these gauges. An indirect way of looking at these field transformations is presented. An example of such results is given and applications are indicated.