bluuebunny/crossref_metadata_2025 huggingface dataset:
HAMILTONIAN LATTICE STUDIES OF CHIRAL MESON FIELD THEORIES
Authors: CHIN SIU A.
Published: July 2002

The latticization of the non-linear sigma model reduces a chiral meson field theory to an O(4) spin lattice system with quantum fluctuations. The result is an interesting marriage between quantum many-body theory and classical spin systems. By solving the resulting lattice Hamiltonian by Monte Carlo methods, the dynamics and thermodynamics of pions can be determined non-perturbatively. In a variational 16 3 lattice study, the ground state chiral phase transition is shown to be first order. Moreover, as the chiral phase transition is approached, the mass gap of pionic collective modes with quantum number of the "ω" vector meson drops toward zero.
Fermi Surface Features and Stripes in Bi2Sr2CaCu2O8+δ Superconductor
Authors: Saini N. L.
Published: July 2002

We have studied momentum distribution of spectral weight around the Fermi level of Bi 2 Sr 2 CaCu 2 0 8+δ (Bi2212) superconductor by angle resolved photoemission to understand implication of the lattice and spin fluctuations on the excitation spectrum of cuprate superconductors. The photointensity reveals shadow bands at (0.5π, 0.5π) and equivalent locations, related to the spin density wave (SDW) and suppression of spectral weight around (π, 0) and equivalent locations, related to an anharmonic and incommensurate charge density wave (ICDW) in the diagonal direction. The work further uncovers the fact that the high Tc appears in a complex phase of coexisting lattice and spin fluctuations.
Dynamic Viscoelasticity of a Magnetorheological Fluid in Oscillatory Slit Flow
Authors: Nakano Masami , Yamamoto Hideki , Jolly Mark R.
Published: July 2002

The nonlinear dynamic viscoelasticity of an MR fluid in oscillatory slit flow under magnetic flux normal to the flow has been investigated by using a newly developed oscillatory pressure flow type rheometer. An MR fluid consisting of micron-sized, magnetically polarizable particles dispersed into a carrier medium is evaluated. The dynamic viscoelasticity remarkably depends on a fluid strain amplitude and a magnetic field strength. Both of the storage modulus (G′) and loss modulus (G″) increase dramatically with the increase of applied magnetic field strength H from 0 to 160 kA/m. And for the increase of the strain amplitude, both of them dramatically decrease, while the loss tangent ( tan δ) increases remarkably, showing the dominance of viscoelastic plastic property. The above results are discussed in terms of three deformation regions of the MR fluid; pre-yield, yield, post-yield.
SO(5) SYMMETRY AND SINGLE PARTICLE SPECTRA
Authors: ZACHER M. G. , DORNEICH A. , EDER R. , HANKE W. , ZHANG S. C.
Published: July 2002

We discuss properties of a recently proposed SO(5) symmetric ladder model. Key features of the single particle spectral function that are emerging from the symmetry are numerically identified in the ladder model and in the photoemission spectrum of the two-dimensional t–J model.
PRESSURE DEPENDENCE OF Tc FROM CHEMICAL EQUILIBRIUM
Authors: KALLIO A. , HISSA J. , HÄYRYNEN T. , BRÄYSY V.
Published: July 2002

Chemical equilibrium theory analogous with dissociation of molecules or ionization of gas of atoms is applied to high-Tc superconductors. The starting point are preformed pairs, which exist in the normal state and can be treated as Coulomb bosons with charge 2e. Above Tc the pairs (B++) decay into fermions (h+) according to the equilibrium reaction B++⇌2h+. Using an approximate chemical equilibrium constant, proportional to pressure we derive a universal two-parameter expression for the pressurized optimum transition temperature [Formula: see text]. The formula shows that [Formula: see text] developes a maximum and beyond the maximum it starts to come down. We also show that in interesting pressure range P>10 GPa, the expansion in powers of pressure diverges.
PREDICTIVE AB-INITIO COMPUTATIONS OF PROPERTIES OF FERROELECTRIC MATERIALS
Authors: BAGAYOKO D. , ZHAO G. L.
Published: July 2002

We present a newly developed, ab-initio, self-consistent procedure for predictive calculations of electronic and related properties of ferroelectric materials. Known as the Bagayoko, Zhao, amd Williams (BZM) procedure, this approach resolves the long-standing disagreement between experimental and theoretical conduction bands, in general, and band gaps, in particular, for ferroelectrical materials and other semiconductors. We discuss applications to tetragonal BaTiO 3 and implications for molecules and band-gap engineering as well as the nuclear shell model.
AUGER EFFECT PROVOKED RED TO GREEN COLOR SHIFT IN THE LUMINESCENCE OF HIGHLY EXCITED Ga1-xAlxAs:Si
Authors: ZEHE A. , RAMÍREZ A.
Published: July 2002

The existence region of {donor-acceptor1-acceptor2}-AUGER molecules is determined in silicon-doped Ga1-xAlxAs by electron-beam excited luminescence measurements at low temperature. The main peak position and luminescence intensity of the donor-acceptor recombination channel turns out to be affected in a characteristic manner on the existence of AUGER molecules at high excitation levels. A shift between two recombination channels can be provoked, which involves the donor-acceptor pair transition at 1.8 eV, and a free-to-bound transition at 2.1 eV. We discuss own luminescence data of Ga0 2Al0 8As , doped with 3·1018 cm-3 silicon atoms. Sample excitation is carried out at 77 K by means of a focused electron beam inside a cryostate. Experimental results are analyzed by use of a set of rate equations, incorporating a particular AUGER process. Good agreement between theoretical and experimental results is established.
GENERALIZED SUPERPOSITIONS OF SQUEEZED COHERENT STATES
Authors: AL-KADER G. M. ABD
Published: July 2002

The superpositions of a pair of squeezed coherent states (SCS) with different squeezing parameters are defined. The characteristic function (CF) for the generalized superpositions of SCSs is given. Photon number distribution for these states is considered. The Q-function for the generalized superposition of SCSs is investigated.
VIRTUAL LATTICE TECHNIQUE AND THE INTERATOMIC POTENTIALS OF ZINC-BLEND-TYPE BINARY COMPOUNDS
Authors: LIU YING , CHEN NAN-XIAN , KANG YAN-MEI
Published: July 2002

Chen's lattice inversion method is expended to calculate the interatomic potentials of zinc-blend-type binary compounds with the virtual lattice technique, which proposes a scheme to obtain the non-empirical interatomic potentials based on the first principle calculation.
MULTIFRACTAL CRITICAL CHAOS GENERATED BY TWO INTERACTING PARTICLES IN A DISORDERED CHAIN: ANDERSON MODEL
Authors: BERSHADSKII A.
Published: July 2002

It is shown, using data of numerical simulations performed by different authors, that multifractal chaos generated by two interacting particles in a disordered chain (in the frames of the Anderson model) belongs to the same class of multifractal chaotic processes as critical chaos generated by the map xn+1=1-a|xn|z via the Feigenbaum scenario. Moreover, a single parameter — multifractal critical index — characterizing this class, takes the same value for both the Anderson quantum chaos and for the universal critical chaos generated by the map xn+1=1-a|xn|3.
SECOND-ORDER CORRELATION FUNCTION FOR SUCCESSIVE SQUEEZED STATES
Authors: POPESCU V. A.
Published: July 2002

By successive application of the squeeze operator, we obtain different quantum statistical properties for the squeezed number, the squeezed thermal, the squeezed coherent and the displaced squeezed thermal states. We compare our enhanced squeezing method with other procedures for superposition of two squeezed coherent states.
CLASSIFICATION OF SIMILAR 2-D OBJECTS BY WAVELET-SPARSE-MATRIX (WSM) METHOD
Authors: FENG L. , BUI T. D. , TANG Y. Y.
Published: July 2002

This paper proposes a novel method called Wavelet-Sparse-Matrix (WSM) to extract the spatial features of 2-D objects for classifying objects that have subtle differences. The differences between these objects are present in the spatial orientations of the objects, or in the local positions of points on the contours of the objects. The separable wavelets are able to distinguish these differences and to separate them into three sparse subpatterns. Sparse matrix technique has the ability to rearrange nonzero elements in a sparse matrix by moving them as close together as possible. WSM method is a combination of these two techniques which can considerably improve the distinction of slightly dissimilar objects. Experiments are conducted, which include a series of discriminative simulations and comparisons with Fourier descriptor and Zernike moment invariant. These experiments verify the feasibility and effectiveness of the WSM method.
A NEURAL NETWORK APPROACH TO REAL-TIME PATTERN RECOGNITION
Authors: MA JINWEN
Published: July 2002

This paper presents a new neural network approach to real-time pattern recognition on a given set of binary (or bipolar) sample patterns. The perceptive neuron of a binary pattern is defined and constructed as a binary neuron with a neighborhood perceptive field. Letting its hidden units be the respective perceptive neurons of the patterns, a three-layer forward neural network is constructed to recognize these patterns with minimum error probability in a noisy environment. The theoretical and simulation analyses show that the network is effective for pattern recognition and can be under strict real-time constraints.
OPTIMALLY FAST CRCW-PRAM TESTING 2D-ARRAYS FOR EXISTENCE OF REPETITIVE PATTERNS
Authors: BRIMKOV VALENTIN E.
Published: July 2002

In classical combinatorial string matching repetitions and other regularities play a central role. Besides their theoretical importance, repetitions in strings have been found relevant to coding and automata theory, formal languages, data compression, and molecular biology. An important motivation for developing a 2D pattern matching theory is seen in its relation with pattern recognition, image processing, computer vision and multimedia. Repetitions in 2D arrays have been defined and classified recently.5 In this paper we present an optimally fast CRCW-PRAM algorithm for testing whether a given n × n array contains repetitions of certain type. The algorithm takes optimal O( log log n) time with [Formula: see text] processors.
CONTOUR DETECTION BASED ON NONLINEAR DISCRETE DIFFUSION IN A CELLULAR NONLINEAR NETWORK
Authors: COMTE J. C. , MARQUIÉ P. , BILBAULT J. M.
Published: July 2002

A contour detection based on a diffusive cellular nonlinear network is proposed. It is shown that there exists a particular nonlinear function for which, numerically, the obtained contour is satisfactory. Furthermore, this nonlinear function can be achieved using analog components.
NONLINEAR TECHNIQUES TO CHARACTERIZE PRECHATTER AND CHATTER VIBRATIONS IN THE MACHINING OF METALS
Authors: JOHNSON M. A. , MOON F. C.
Published: July 2002

In this paper we report on the use of Poincaré sections, phase plane portraits and false nearest neighbor techniques to understand bifurcations in the lathe cutting of aluminum. The experiments presented here offer further evidence of deterministic tool vibrations below the classical onset of chatter. While classical chatter exhibits strong periodic content, these prechatter dynamics exhibit both quasiperiodic and chaotic vibrations. The method of false nearest neighbors predicts an embedding dimenion between 4 and 6 for prechatter cutting conditions while showing a random characteristic for no-cutting running of the machine.

A one-dimensional delay-differential equation model is presented which exhibits some of the characteristics of the Poincaré sections of the experimental time series.
NONLINEAR AMPLIFICATION EFFECTS IN A PERIOD-DOUBLING SERIES RESONANCE CIRCUIT
Authors: DIESTELHORST M. , KAPSCH R.-P. , BEIGE H.
Published: July 2002

The influence of small near-resonant perturbations on the period-doubling bifurcations in a nonlinear series resonance circuit has been investigated in detail. The series resonance circuit contains ferroelectric triglycine sulfate (TGS) as nonlinear capacitor. If the temperature of the TGS-crystal is below the Curie-temperature this dynamical system is a good experimental realization of a Duffing-like oscillator with double-well potential. The depth of the double-well potential may be changed easily by temperature variation of the TGS-crystal. Variation of the amplitude of the driving voltage in the order of magnitude of the coercive field strength and the frequency of the driving voltage in the range of domain relaxation can be used to tune the system towards period-doubling bifurcations. An additional near-resonant perturbation has been introduced into the system by amplitude modulation of the driving voltage. The observed effects (small signal amplification, shift of the bifurcation point, multiple-side peaks around odd harmonics of half the driving frequency) are compared to theoretically derived results. They are well understood on the basis of the center manifold analysis taking into account nonlinear effects in the normal form of the period-doubling bifurcation.
BREAKDOWN OF LIBRATIONAL INVARIANT SURFACES
Authors: ANDREU MIQUEL ANGEL , CELLETTI ALESSANDRA , FALCOLINI CORRADO
Published: July 2002

A numerical investigation of the stability of invariant librational tori is presented. The method has been developed for a model describing the spin-orbit coupling in Celestial Mechanics. Periodic orbits approaching the librational torus are computed by means of Newton's method. According to Greene's criterion, their stability is strictly related to the survival of invariant tori.

We consider librational tori around the main spin-orbit resonances (1:1, 3:2). Their existence provides the stability of the resonances, due to the confinement properties in the three-dimensional phase space associated to our model. The results are consistent with the actual observations of the eccentricity and of the oblateness parameter. A different behavior of the Moon and Mercury around the main resonances is evidenced, providing interesting suggestions about the different probabilities of capture in a resonance.
ON ROOT MULTIPLICITIES OF $H A_n^{(1)}$
Authors: HONTZ JENNIFER , MISRA KAILASH C.
Published: July 2002

We determine the root multiplicities of the Kac–Moody Lie algebra [Formula: see text] of indefinite type using a recursive root multiplicity formula due to Kang. We view [Formula: see text] as a representation of its subalgebra [Formula: see text] and then use the combinatorics of the irreducible representations of [Formula: see text] to determine the root multiplicities.
COMPUTING THE JONES POLYNOMIAL ON BIPARTITE GRAPHS
Authors: MIGHTON JOHN
Published: July 2002

From any knot or link it is possible to derive a labelled bipartite graph from which one may compute the Jones Polynomial. The graphs shed new light on the computational properties of the Jones polynomial and may themselves be regarded as a new kind of knot invariant.
WHEELER–DEWITT EQUATION WITH VARIABLE CONSTANTS
Authors: BELINCHÓN JOSÉ ANTONIO
Published: July 2002

In this paper we study how all the physical "constants" vary in the framework described by a model in which we have taken into account the generalize conservation principle for its stress-energy tensor. This possibility enable us to take into account the adiabatic matter creation in order to get rid of the entropy problem. We try to generalize this situation by contemplating multi-fluid components. To validate all the obtained results we explore the possibility of considering the variation of the "constants" in the quantum cosmological scenario described by the Wheeler–DeWitt equation. For this purpose we explore the Wheeler–DeWitt equation in different contexts but from a dimensional point of view. We end by presenting the Wheeler–DeWitt equation in the case of considering all the constants varying. The quantum potential is obtained and the tunneling probability is studied.
ON BOUNDARY TERMS AND CONFORMAL TRANSFORMATIONS IN CURVED SPACETIMES
Authors: CASADIO R. , GRUPPUSO A.
Published: July 2002

We intend to clarify the interplay between boundary terms and conformal transformations in scalar-tensor theories of gravity. We first consider the action for pure gravity in five dimensions and show that, on compactifing a la Kaluza–Klein to four dimensions, one obtains the correct boundary terms in the Jordan (or String) Frame form of the Brans–Dicke action. Further, we analyze how the boundary terms change under the conformal transformations which lead to the Pauli (or Einstein) frame and to the nonminimally coupled massless scalar field. In particular, we study the behaviour of the total energy in asymptotically flat spacetimes as it results from surface terms in the Hamiltonian formalism.
THE SOLITON STARS EVOLUTION
Authors: BEDNAREK ILONA , MAŃKA RYSZARD
Published: July 2002

The evolution of a soliton star filled with fermions is studied in the framework of general relativity. Such a system could be described by the surface tension σ0, the bag constant B, and the fermion number density ρ. One of the parameters mentioned above could prevail in the system and thus affect the spacetime inside the bubble. Whether it is described by Friedman or de Sitter metric depends on the prevailing parameter. In broad outline, the whole spacetime is divided by the surface of the soliton into the false vacuum region inside the soliton and the true vacuum region outside, the latter being described by the Schwarzschild line element. The aim of this paper is to study the equations of motion of the domain wall in two cases. In both of them, the Schwarzschild metric is outside the soliton. The de Sitter metric describes the interior in the first case, and in the second case, it is replaced by the Friedman metric. Analyzing obtained equations, one can draw conclusions concerning the further evolution of the soliton star.
SYMMETRY REDUCED EINSTEIN GRAVITY AND GENERALIZED σ AND CHIRAL MODELS
Authors: ASHTEKAR ABHAY , HUSAIN VIQAR
Published: July 2002

Certain features associated with the symmetry reduction of the vacuum Einstein equations by two commuting, spacelike Killing vector fields are studied. In particular, the discussion encompasses the equations for the Gowdy T3 cosmology and cylindrical gravitational waves. We first point out a relation between the SL(2,R) (or SO(3)) σ and principal chiral models, and then show that the reduced Einstein equations can be obtained from a dimensional reduction of the standard SL(2,R) σ-model in three dimensions. The reduced equations can also be derived from the action of a 'generalized' two dimensional SL(2,R) σ-model with a time dependent constraint. We give a Hamiltonian formulation of this action, and show that the Hamiltonian evolution equations for certain phase space variables are those of a certain generalization of the principal chiral model. Using these Hamiltonian equations, we give a prescription for obtaining an infinite set of constants of motion explicitly as functionals of the spacetime metric variables.
STRANGE STARS IN LOW-MASS BINARY PULSAR SYSTEMS
Authors: HORVATH J. E.
Published: July 2002

Based on observational facts and a variety of theoretical arguments we discuss in this work the possibility that pulsars in Low-Mass Binary Pulsar systems could be strange stars rather than neutron stars. It is shown that, although subject to reasonable uncertainties, the consideration of the physics of the SQM core and thin normal crusts leads to the prediction of several observed features of the magnetic field history of these systems within this working hypothesis.
SHELL MODEL CALCULATIONS OF 3T, 5He AND 6Li NUCLEI
Authors: EL-NOHY NAZIH
Published: July 2002

The bases of the translation invariant shell model are used to construct the ground-state wave functions of 3 T , 5 He and 6 Li . For 3 T the bases used correspond to the number of quanta of excitation N up to ten. For 5 He and 6 Li the bases used correspond to the number of quanta of excitation N up to six. The model is applied to calculate the binding energy and the root mean square radius for 3 T , 5 He and 6 Li nuclei. The residual interactions used consist of central, tensor, spin-orbit and quadratic spin-orbit terms with Gaussian radial dependence. The parameters of these interactions are chosen in such away that they represent the long range attraction and the short range repulsion of nucleon interactions. It was found that this potential is more suitable for calculating the characteristics of these nuclei, and better than other potentials, such as our previous potentials which were represented by the parameters of long range attraction forces only. For 3T we obtained good agreement between calculated and experimental values of both the ground state binding energy and the root mean square radius. For 5 He and 6 Li nuclei we obtained an acceptable improvement with these calculations over other potentials.
THE MORPHOGENESIS OF HIGH SYMMETRY: THE WARPING THEOREM
Authors: MARZEC CHRISTOPHER J.
Published: July 2002

A theorem is presented concerning the morphogenesis of high-symmetry structures made of three-dimensional morphological units (MU's) free to move in three dimensions or constrained to a surface. All parts of each MU interact non-specifically with the rest of the structure, via an isotropic function of distance. Summing all interactions gives a net figure of merit, ℐ, that depends upon MU positions and orientations. A structure evolves via gradient dynamics, each MU moving down the local gradient of ℐ. The analysis is represented with generality in Fourier space.

A "warping" from a configuration of MU's is a set of MU displacements and/or rotations that slightly perturb nearest neighbor relations; deviations can accrue across the structure, producing large global distortions. A warping behaves qualitatively like a small perturbation, so a warping from a stable equilibrium decays under gradient dynamics. Connection to the Symmetrization Theorem greatly extends the basin of attraction of stable symmetrical configurations. Warped configurations are equivalent as precursors of structure, which helps to understand assembly by accretion.

Numerical illustrations are given in cylindrical geometry, for application to phyllotaxis; and in spherical geometry, for virus capsid structure. For animations of numerical evolutions that find high symmetry via unwarping, see
COMMITTEES OF LEARNING AGENTS
Authors: ASKER LARS , DANIELSON MATS , EKENBERG LOVE
Published: July 2002

We describe how machine learning and decision theory is combined in an application that supports control room operators of a combined heating and power plant to cope with the overwhelming complexity of situations when severe plant disturbances occur. The application is designed as an assistant, rather than as an automatic system that intervenes directly in the operator/plant loop. The application is required to handle vague and numerically imprecise background information in the construction of classifier committees. A classifier committee (or ensemble) is a classifier created by combining the predictions of multiple sub-classifiers. The presented method combines classifiers into a committee by using computational methods for decision analysis that are designed to work when the information at hand is imprecise. The application evaluates and make priorities between classified alarms according to credibilities that depend on the current context. Machine learning techniques are used to construct classifiers that recognize various malfunctions in a process, determine whether a situation is normal or not, and make priorities among alarms.
AB-INITIO STUDY OF THE STRUCTURE OF Pd(110)-c(4×2)-BENZENE
Authors: FAVOT FABIO , DAL CORSO ANDREA , BALDERESCHI ALFONSO
Published: July 2002

From first principle calculations we have determined the structure of the Pd(110)-c(4×2)-benzene system for three azimuthally different orientations of the benzene molecule (two with C2v and one with C2 symmetry). For all cases, in the relaxed structure the benzene molecule loses its planar geometry since the C–H bonds appreciably bend upwards, the carbon hexagon loses planar geometry too and exhibits inequivalent C–C bond lengths, and the substrate is slightly buckled. We discuss the calculated geometries in terms of benzene–substrate interactions and predict a C2 symmetry of the adsorbed molecule.
EFFECT OF Cu DEPOSITION AND ANNEALING UPON A GaSe/Si(111) HETEROJUNCTION
Authors: ABIDRI B. , LACHARME J.-P. , GHAMNIA M. , SÉBENNE C. A. , EDDRIEF M. , ZERROUKI M.
Published: July 2002

Single crystal substrates of GaSe, a layered semiconductor with a 2 eV band gap, were epitaxially grown by MBE onto a Si(111)(1×1)–H substrate, forming a perfectly abrupt heterojunction. Controlled amounts of Cu were sequentially deposited onto the clean passive surface of GaSe from a few tenths to several hundred monolayers (1 ML refers to the GaSe surface: 8 × 1014 at/cm 2). After given Cu depositions, the effect of UHV annealings at increasing temperatures was studied, until GaSe removal. The system was characterized as a function of either Cu deposit or annealing temperature using low energy electron diffraction, Auger electron spectroscopy and photoemission yield spectroscopy. The room temperature interaction starts as an apparent intercalation process until Cu islands begin to form, beyond about 50 ML. Upon annealings as low as 250°C, several ML of Cu disappear into the bulk of an apparently recovered GaSe, towards the GaSe/Si interface.
VARIATIONS IN THE QUANTITY OF TYPE II COLLAGEN IN CARPAL TUNNEL SYNDROME AND TRIGGER FINGER
Authors: Kramer Adriel A. , Weiss Arnold-Peter C. , Barrach Hans-J. , Akelman Edward
Published: July 2002

Carpal tunnel syndrome (CTS) and trigger finger (TF) are two related disorders which involve alterations in the normal mechanical loading of tendon sheath pulleys. This study examines the presence of Type II collagen in the carpal ligament and A-1 pulley by Western blotting to determine the extent of cartilage metaplasia that may occur in these tissues. Cyanogen bromide peptides generated from tissue supplied from 77 patients were separated by SDS-PAGE and transferred to nitrocellulose. The membranes were stained with the E1E5 monoclonal antibody and collagen levels were quantified. All specimens were found to contain at least small amounts of Type II collagen. Approximately 15 percent of the samples from patients with carpal tunnel syndrome and trigger finger were found to contain significantly elevated levels of Type II collagen. All specimens with high levels of Type II collagen were found in female patients. These increases may indicate the presence of cartilage metaplasia enabling the tissue to counteract compressive loads. With further study, tissue staining techniques using monoclonal antibodies may provide useful clinical information on severity or long-term outcome prognosis.
Ulnar Styloid Fracture with Distal Radioulnar Joint Subluxation/Dislocation
Authors: Nakamura Ryogo , Horii Emiko , Imaeda Toshihiko , Nakao Etsuhiro , Kato Hitoshi
Published: July 2002

In 55 patients with ulnar styloid fractures, the site and displacement of the fracture was examined in relation to distal radioulnar joint subluxation/dislocation by computed tomography (CT). Distal radioulnar joint subluxation/dislocation confirmed with CT in 18 of 55 patients, irrespective of the site of the ulnar styloid fracture. In 21 patients with nondisplaced styloid fractures, only 3 fractures were associated with distal radioulnar joint subluxation/dislocation. In 34 patients where the styloid fracture was displaced for 3 mm or more, 15 fractures were associated with a distal radioulnar joint subluxation/dislocation. Therefore, ulnar styloid displacement of 3 mm or more suggests the need for further examination of the distal radioulnar joint.
OLD UNREDUCED DISLOCATION OF THE INTERPHALANGEAL JOINT OF THE THUMB
Authors: Patankar Hemant , Shah Chandrakant
Published: July 2002

A case of two-and-a-half years old unreduced, irreducible dislocation of the interphalangeal joint of the thumb, treated initially by gradual external distraction and later by interphalangeal joint arthrodesis is reported. The advantages of gradual external distraction over open reduction in cases of unreduced and irreducible dislocations are discussed.
A THRESHOLD MODEL FOR STOCK RETURN VOLATILITY AND TRADING VOLUME
Authors: IORI GIULIA
Published: July 2002

We propose a model with heterogeneous interacting traders which can explain the observed cross-correlation between stock return volatility and trading volume. Transaction costs are introduced which, by responding to price movements, create a feedback mechanism on future trading and generates volatility clustering.
A NEW FAMILY OF EXTREMAL INTERCONNECTION NETWORKS
Authors: HARWOOD AARON , SHEN HONG
Published: July 2002

We extensively discuss a new interconnection network topology, denoted by ϒ(n,r). Firstly, the ϒ(n,2) network is shown to provide average cost 3 log 2 n while providing superior fault tolerance characteristics. It is defined over any natural number of nodes n using 2n-3 edges for an average degree of 4 and has diameter no greater than k=⌈ log 2n⌉ with average diameter as small as [Formula: see text]. The network is planar and has cyclomatic number n-2. For n=2t the unbounded maximum degree is 2 log 2 n-1 believed indicative of generally a maximum unbounded degree O( log 2n). The bisection width ranges from 3 when n=2t to t+1 when n=2t+1. Secondly, we provide the ϒ*(n,r) network of bounded degree 2r. For n=rt the ϒ*(n,r) network has asymptotically better average cost than the general deBruijn(r,t) network while also maintaining planarity and cyclomatic property of ϒ(n,2). The ϒ family exhibits unique extremal properties of both theoretical interest and practical importance.
VIBRATION AND BUCKLING OF SS-F-SS-F RECTANGULAR PLATES LOADED BY IN-PLANE MOMENTS
Authors: KANG JAE-HOON , LEISSA ARTHUR W.
Published: July 2002

This paper presents exact solutions for the free vibrations and buckling of rectangular plates having two opposite, simply supported edges subjected to linearly varying normal stresses causing pure in-plane moments, the other two edges being free. Assuming displacement functions which are sinusoidal in the direction of loading (x), the simply supported edge conditions are satisfied exactly. With this the differential equation of motion for the plate is reduced to an ordinary one having variable coefficients (in y). This equation is solved exactly by assuming power series in y and obtaining its proper coefficients (the method of Frobenius). Applying the free edge boundary conditions at y=0, b yields a fourth order characteristic determinant for the critical buckling moments and vibration frequencies. Convergence of the series is studied carefully. Numerical results are obtained for the critical buckling moments and some of their associated mode shapes. Comparisons are made with known results from less accurate one-dimensional beam theory. Free vibration frequency and mode shape results are also presented. Because the buckling and frequency parameters depend upon the Poisson's ratio (ν), results are shown for 0≤ν≤0.5, valid for isotropic materials.
ADAPTIVE NOISE CANCELLATION FOR MULTI-SENSORY SIGNALS
Authors: VOROBYOV SERGIY A. , CICHOCKI ANDRZEJ , BODYANSKIY YEVGENIY V.
Published: July 2002

This paper describes a fast adaptive algorithm for noise cancellation using multi-sensory signal recordings of the same noisy source. It is shown that the performance of the new procedure for noise cancellation for multi-sensory signals is improved when compared to previously proposed methods. A short overview of the previously proposed methods is given. Optimality of the algorithm is discussed and numerical simulation is included to show the validity and effectiveness of the algorithm.
COOPERATIVE PARRONDO'S GAMES
Authors: TORAL RAÚL
Published: July 2002

We introduce a new family of Parrondo's games of alternating losing strategies in order to get a winning result. In our version of the games we consider an ensemble of players and use "social" rules in which the probabilities of the games are defined in terms of the actual state of the neighbors of a given player.
EFFECTS OF QUANTUM CONFINEMENT ON LOW FREQUENCY NOISE IN δ-DOPED GaAs STRUCTURES GROWN BY MBE
Authors: CHEN X. Y. , KOENRAAD P. M.
Published: July 2002

Low frequency noise (LFN) was measured in δ-doped GaAs structures in which the free carriers are confined to a 2-dimensional plane. Three samples grown at different temperatures, resulting in doping layers of a different thickness, are used to study the effects of quantum confinement on the LFN. We observed both 1/f noise and generation-recombination noise components. We find that a stronger quantum confinement results in a bigger Hall mobility and a lower magnitude of the 1/f noise.
CONJUGATION OF FLOWS FOR STOCHASTIC AND RANDOM FUNCTIONAL DIFFERENTIAL EQUATIONS
Authors: LISEI HANNELORE
Published: July 2002

The purpose of this paper is to transform a stochastic functional differential equation driven by a continuous helix spatial semimartingale of Kunita type into a random functional differential equation by using a stationary bijective random process.
SYSTEM/U: a database system based on the universal relation assumption
Authors: Korth Henry F. , Kuper Gabriel M. , Feigenbaum Joan , van Gelder Allen , Ullman Jeffrey D.
Published: July 2002

System/U is a universal relation database system under development at Standford University which uses the language C on UNIX. The system is intended to test the use of the universal view, in which the entire database is seen as one relation. This paper describes the theory behind System/U, in particular the theory of maximal objects and the connection between a set of attributes. We also describe the implementation of the DDL (Data Description Language) and the DML (Data Manipulation Language), and discuss in detail how the DDL finds maximal objects and how the DML determines the connection between the attributes that appear in a query.
The active badge location system
Authors: Want Roy , Hopper Andy , Falcão Veronica , Gibbons Jonathan
Published: July 2002

A novel system for the location of people in an office environment is described. Members of staff wear badges that transmit signals providing information about their location to a centralized location service, through a network of sensors. The paper also examines alternative location techniques, system design issues and applications, particularly relating to telephone call routing. Location systems raise concerns about the privacy of an individual and these issues are also addressed.
ODEXPERT: an expert system to select numerical solvers for initial value ODE systems
Authors: Kamel M. S. , Enright W. H. , Ma K. S.
Published: July 2002

ODEXPERT is a prototype knowledge-based system which selects the appropriate numerical solvers for initial value ordinary differential equations. It is capable of deriving some knowledge about the input problem by performing automated tests to detect properties and structures in the problem which guide the selection process.
From text to hypertext by indexing
Authors: Salminen Airi , Tague-Sutcliffe Jean , McClellan Charles
Published: July 2002

A model is presented for converting a collection of documents to hypertext by means of indexing. The documents are assumed to be semistructured, i.e., their text is a hierarchy of parts, and some of the parts consist of natural language. The model is intended as a framework for specifying hypertextual reading capabilities for specific application areas and for developing new automated tools for the conversion of semistructured text to hypertext. In the model, two well-known paradigms—formal grammars and document indexing—are combined.

The structure of the source text is defined by a schema that is a constrained context-free grammar. The hierarchic structure of the source may thus be modeled by a parse tree for the grammar. The effect of indexing is described by grammar transformations. The new grammar, called an indexing schema, is associated with a new parse tree where some text parts are index elements. The indexing schema may hide some parts of the original documents or the structure of some parts. For information retrieval, parts of the indexed text are considered to be nodes of a hypergraph. In the hypergraph-based information access, the navigation capabilities of the hypertext systems are combined with the querying capabilities of information retrieval systems.
Sharing memory robustly in message-passing systems
Authors: Attiya Hagit , Bar-Noy Amotz , Dolev Danny
Published: July 2002

Emulators that translate algorithms from the shared-memory model to two different message-passing models are presented. Both are achieved by implementing a wait-free, atomic, single-writer multi-reader register in unreliable, asynchronous networks. The two message-passing models considered are a complete network with processor failures and an arbitrary network with dynamic link failures.

These results make it possible to view the shared-memory model as a higher-level language for designing algorithms in asynchronous distributed systems. Any wait-free algorithm based on atomic, single-writer multi-reader registers can be automatically emulated in message-passing systems, provided that at least a majority of the processors are not faulty and remain connected. The overhead introduced by these emulations is polynomial in the number of processors in the system.

Immediate new results are obtained by applying the emulators to known shared-memory algorithms. These include, among others, protocols to solve the following problems in the message-passing model in the presence of processor or link failures: multi-writer multi-reader registers, concurrent time-stamp systems,l-exclusion, atomic snapshots, randomized consensus, and implementation of data structures.
Validating real-time systems by history-checking TRIO specifications
Authors: Felder Miguel , Morzenti Angelo
Published: July 2002

We emphasize the importance of formal executable specifications in the development of real-time systems, as a means to assess the adequacy of the requirements before a costly development process takes place. TRIO is a first-order temporal logic language for executable specification of real-time systems that deals with time in a quantitative way by providing a metric to indicate distance in time between events and length of time intervals. We summarize the language and its model-parametric semantics. Then we present an algorithm to perform history checking, i.e., to check that a history of the system satisfies the specification. This algorithm can be used as a basis for an effective specification testing tool. The algorithm is described; an estimation of its complexity is provided; and the main functionalities of the tool are presented, together with sample test cases. Finally, we draw conclusions and indicate directions of future research.
Object-oriented cosynthesis of distributed embedded systems
Authors: Wolf Wayne
Published: July 2002

This article describes a new hardware-software cosynthesis algorithm that takes advantage of the structure inherent in an object-oriented specification. The algorithm creates a distributed system implementation with arbitrary topology, using the object-oriented structure to partition functionality in addition to scheduling and allocating processes. Process partitioning is an especially important optimization for such systems because the specification will not, in general, take into account the process structure required for efficient execution on the distributed engine. The object-oriented specification naturally provides both coarse-grained and fine-grained partitions of the system. Our algorithm uses that multilevel structure to guide synthesis. Experimental results show that our algorithm takes advantage of the object-oriented specification to quickly converge on high-quality implementations.
A simple min-cut algorithm
Authors: Stoer Mechthild , Wagner Frank
Published: July 2002

We present an algorithm for finding the minimum cut of an undirected edge-weighted graph. It is simple in every respect. It has a short and compact description, is easy to implement, and has a surprisingly simple proof of correctness. Its runtime matches that of the fastest algorithm known. The runtime analysis is straightforward. In contrast to nearly all approaches so far, the algorithm uses no flow techniques. Roughly speaking, the algorithm consists of about |
V
| nearly identical phases each of which is a
maximum adjacency search
.
Practical experience in the numerical dangers of heterogeneous computing
Authors: Blackford L. S. , Cleary A. , Petitet A. , Whaley R. C. , Demmel J. , Dhillon I. , Ren H. , Stanley K. , Dongarra J. , Hammarling S.
Published: July 2002

Special challenges exist in writing reliable numerical library software for heterogeneous computing environments. Although a lot of software for distributed-memory parallel computers has been written, porting this software to a network of workstations requires careful consideration. The symptoms of heterogeneous computing failures can range from erroneous results without warning to deadlock. Some of the problems are straightforward to solve, but for others the solutions are not so obvious, or incur an unacceptable overhead. Making software robust on heterogeneous systems often requires additional communication. We describe and illustrate the problems encountered during the development of ScaLAPACK and the NAG Numerical PVM Library. Where possible, we suggest ways to avoid potential pitfalls, or if that is not possible, we recommend that the software not be used on heterogeneous networks.
User-oriented criteria for the selection of DSS software
Authors: Reimann Bernard C. , Waren Allan D.
Published: July 2002

Both the composition of the selection team and the choice of evaluation criteria should reflect the end-user orientation of DSS software.
Complexity estimates depending on condition and round-off error
Authors: Cucker Felipe , Smale Steve
Published: July 2002

This paper has two agendas. One is to develop the foundations of round-off in computation. The other is to describe an algorithm for deciding feasibility for polynomial systems of equations and inequalities together with its complexity analysis and its round-off properties. Each role reinforces the other.
Multistep Methods With Modified Predictors and Correctors
Authors: Kohfeld J. J. , Thompson G. T.
Published: July 2002

In April, 1964, Gragg and Stetter published a set of numerical methods for solving
y′
=
f
(
x
,
y
) which rely on some very accurate correctors, using a “nonstep” point within the interval of integration. However, the present authors found that this accuracy is largely lost unless one also uses accurate predictors, also using a “nonstep” point within an interval of integration, of the same order of accuracy as that of the correctors. Numerical examples indicate that on the average those differential equations tested can be solved by the method of the sixth order proposed in this paper in about two-thirds the time required by an Adams method of the same order.
PL360, a Programming Language for the 360 Computers
Authors: Wirth Niklaus
Published: July 2002

A programming language for the IBM 360 computers and aspects of its implementation are described. The language, called PL360, provides the facilities of a symbolic machine language, but displays a structure defined by a recursive syntax. PL360 was designed to improve the readability of programs which must take into account specific characteristics and limitations of a particular computer. It represents an attempt to further the state of the art of programming by encouraging and even forcing the programmer to improve his style of exposition and his principles and discipline in program organization. Because of its inherent simplicity, the language is particularly well suited for tutorial purposes.

The attempt to present a computer as a systematically organized entity is also hoped to be of interest to designers of future computers.
Inversion of Modified Symmetric Matrices
Authors: Zielke Gerhard
Published: July 2002

The problem to be solved is the computation of the inverse of a modified symmetric matrix if the inverse of the original symmetric matrix is already known. By “modified” it is meant that the two symmetric matrices differ from each other in two symmetric elements or columns and rows. For both cases new identities and ALGOL algorithms are derived.
A Human Oriented Logic for Automatic Theorem-Proving
Authors: Nevins Arthur J.
Published: July 2002

A deductive system is described which combines aspects of resolution (e.g. unification and the use of Skolem functions) with that of natural deduction and whose performance compares favorably with the best predicate calculus theorem provers.
An implementation of a Fourier series method for the numerical inversion of the Laplace transform
Authors: D'Amore Luisa , Laccetti Guiliano , Murli Almerico
Published: July 2002

Our method is based on the numerical evaluation of the integral which occurs in the Riemann Inversion formula. The trapezoidal rule approximation to this integral reduces to a Fourier series. We analyze the corresponding discretization error and demonstrate how this expression can be used in the development of an
automatic routine
, one in which the user needs to specify only the required accuracy.
Tools and approaches for developing data-intensive Web applications
Authors: Fraternali Piero
Published: July 2002

The exponential growth and capillar diffusion of the Web are nurturing a novel generation of applications, characterized by a direct business-to-customer relationship. The development of such applications is a hybrid between traditional IS development and Hypermedia authoring, and challenges the existing tools and approaches for software production. This paper investigates the current situation of Web development tools, both in the commercial and research fields, by identifying and characterizing different categories of solutions, evaluating their adequacy to the requirements of Web application development, enlightening open problems, and exposing possible future trends.
Some numerical experiments using Newton's method for nonlinear parabolic and elliptic boundary-value problems
Authors: Bellman Richard , Juncosa Mario L. , Kalaba Robert
Published: July 2002

Using a generalization of Newton's method, a non-linear parabolic equation of the form

u
t

-

u
xx

=
g
(
u
), and a non-linear elliptic equation

u
xx

+

u
yy

=

e
u

, are solved numerically. Comparison of these results with results obtained using the Picard iteration procedure show that in many cases the quasilinearization method offers substantial advantages in both time and accuracy.
Advanced computers
Authors: Brouse R. A.
Published: July 2002

The objective is to investigate significant developments in advanced computers and to explore the relationship between programming and new concepts of computer organization. Two specific studies are in progress: Data Sequencing and Vertical Data Processing.
Some practical experience with a software quality assurance program
Authors: Gustafson G. G. , Kerr Roberta J.
Published: July 2002

Within a production programming environment, a software quality assurance program (QAP) was instituted to produce standards, conventions, and methodologies for all phases of the software development process. Software language standards and several support processors, in turn, developed. The authors offer a plan which may help others avoid some of the pitfalls they experienced while attempting to construct a meaningful software QAP.
Authoring systems in computer based education
Authors: Kearsley Greg
Published: July 2002

The idea of a programming system which generates other programs (referred to as automatic programming or metasoftware) has always been a popular one in computer science. Despite the interest, however, few such systems have actually been inplemented and used. An exception is the development and use of
authoring systems
in the domain of Computer Based Education (CBE). This article surveys the development and characteristics of authoring systems.