bluuebunny/crossref_metadata_2025 huggingface dataset:
NONLINEAR ASPECTS OF NUCLEAR MANY-BODY THEORY
Authors: Dickhoff W.H.
Published: November 2004

New developments in the self-consistent Green’s function (SCGF) method as applied to nuclear systems are discussed. Results for high-momentum components in the single-particle spectral function of 16O reveal that their observation is only feasible at a correspondingly high excitation energy in the (e, e′p) reaction. The consequences of the non-mean-field character of nucleons in the nuclear medium are further explored in the context of the nuclear matter saturation problem.
LATTICE COMPUTATION OF A MAGNETIC MONOPOLE MASS
Authors: SMIT J. , SIJS A.J. VAN DER
Published: November 2004

A single magnetic monopole in pure SU(2) gauge theory is simulated on the lattice and its mass is computed in the full quantum theory. The results are relevant for our proposed realization of the dual superconductor hypothesis of confinement.
MONTE CARLO CALCULATIONS FOR QUANTUM CHROMODYNAMICS USING A MASSIVELY PARALLEL COMPUTER
Authors: Stamatescu I.O.
Published: November 2004

We present the QCD-TARO program of calculations for lattice Quantum Chromo-dynamics which uses the parallel computer AP1000 of Fujitsu.
NUMERICAL SIMULATION OF THE KdV-MKdV EQUATION
Authors: TAHA THIAB R.
Published: November 2004

In this paper two numerical schemes for the numerical simulation of the nonlinear partial differential equation ut+6αuux+6βu2ux+uxxx=0 are implemented by the method of lines (MOL). The first scheme is based on the inverse scattering transform (IST), and the second scheme is a combination of the IST schemes for the Korteweg-de Vries (KdV) and modified KdV (MKdV) equations. The only difference between the two schemes is in the discretization of the nonlinear terms. Numerical experiments have shown that the first scheme is significantly more accurate than the second one. This demonstrates the importance of a proper discretization of nonlinear terms when a numerical method is designed for solving a nonlinear differential equation.
A SURVEY OF PARALLEL MULTIVARIATE NUMERICAL INTEGRATION: RECENT RESULTS AND DEVELOPMENTS
Authors: VAKALIS IGNATIOS E.
Published: November 2004

The main objective of this work is to present a survey of the most recently developed parallel multivariate integration routines for various architectures (MIMDDM, MIMD-SM, Network of workstations). Applications to computational physics problems is also provided.
ANALYSIS OF RANDOM NUMBER GENERATORS USING MONTE CARLO SIMULATION
Authors: CODDINGTON P.D.
Published: November 2004

Monte Carlo simulation is one of the main applications involving the use of random number generators. It is also one of the best methods of testing the randomness properties of such generators, by comparing results of simulations using different generators with each other, or with analytic results. Here we compare the performance of some popular random number generators by high precision Monte Carlo simulation of the 2-d Ising model, for which exact results are known, using the Metropolis, Swendsen-Wang, and Wolff Monte Carlo algorithms. Many widely used generators that perform well in standard statistical tests are shown to fail these Monte Carlo tests.
A FAST ALGORITHM FOR RANDOM SEQUENTIAL ADSORPTION OF DISCS
Authors: WANG JIAN-SHENG
Published: November 2004

An efficient simulation algorithm for random sequential adsorption of discs is implemented. By dividing the surface into small squares, depositions are attempted only on squares that are actually possible. A crucial part is a method to identify the available squares. A precise value of the jamming coverage is obtained: θ(∞)≈0.547069. The asymptotic law θ(t)≈θ(∞)−ct−1/2 is verified to a high accuracy. The pair correlation function at the jamming state is analyzed.
LOGARITHMIC FACTORS IN THE DYNAMICS OF THE FOUR-DIMENSIONAL ISING MODEL
Authors: STAUFFER DIETRICH
Published: November 2004

Simulations at the critical point for short times t agree in part with the expected logarithmic powers for systems up to 3364.
FINITE DIFFERENCE MODELS ENTIRELY INHERITING CONTINUOUS SYMMETRY OF ORIGINAL DIFFERENTIAL EQUATIONS
Authors: DORODNITSYN V.A.
Published: November 2004

The present paper is concerned with continuous groups of transformations in a space of discrete variables. The criterion of invariance of difference equations together with difference grid is discussed. One simple method to construct finite-difference equations and grids entirely inheriting admitted Lie groups of transformations of initial differential models is developed.
AN AUTOMATED SYSTEM FOR THE MAINTENANCE OF MULTIFORM DOCUMENTATION
Authors: ROUSSEAU BERTRAND , RUGGIER MARIO , SMITH MATTHIEW
Published: November 2004

Software documentation for the user often exists in several forms including paper, electronic, on-line help, etc. We have build a system to help with the writing and maintenance of such kinds of documentation which relies on the FrameMaker product. As an example, we show how it is used to maintain the ADAMO documentation, delivered in 4 incarnations on paper, WWW hypertext, KUIP and running examples. The use of the system results in both time saving and quality improvements.
ON THE Zn-DOPING INDUCED EFFECTS IN La2−xSrx(Cu1−yZny)O4
Authors: OLEJNICZAK J. , ZALESKI A.J. , CISZEK M.
Published: November 2004

We have studied the effects of Zn -doping on the transport properties of La 2−x Sr x( Cu 1−y Zn y) O 4. We have observed anomalously strong doping-induced increase of resistivity below 100 K together with “normal-metal” behavior of resistivity at higher temperatures (T>250 K ). These data seem to support a model in which Zn impurity influences strongly the properties of the twin boundaries.
CONTRIBUTION OF INTERBLOCK COUPLING TO Tc IN HIGH-Tc BI OXIDES
Authors: GRIGORYAN L. , YAKUSHI K. , NARLIKAR A.V. , SAMANTHA S.B.
Published: November 2004

Magnetization, optical, and scanning tunneling microscopy/spectroscopy studies of Bi-2212 and 2223 oxides intercalated by metal phthalocyanine (MPc) are presented. At the low level of MPc uptake, the diamagnetic response of the Bi-2212 single crystals along the c axis is severely suppressed accompanied by a sharp drop in Tc. Since at that stage the number of charge carriers is not affected as evidenced by the optical spectra, the Tc drop is ascribed to the decoupling of the unit cell blocks due to insertion of the insulating MPc molecules between the Bi-O bilayers. Magnitude of the Tc drop is in a reasonable agreement with the estimates of the resonating valence bond model.
SUPERCONDUCTOR-INSULATOR TRANSITIONS IN TWO DIMENSIONS
Authors: LIU Y. , GOLDMAN A.M.
Published: November 2004

The current status of the experimental study of the superconductor-to-insulator transition is reviewed for systems which are two-dimensional and nominally homogeneous. Interest in this problem has been heightened by the prospect that the transition may be representative of a new class of quantum phase transitions at zero temperature. An ubiquitous feature of the experiments is that films, depending on their properties, or the value of an applied magnetic field, exhibit either insulating or superconducting behavior in the limit of zero temperature. In particular, there appears to exist a limiting behavior which is associated with a finite zero-temperature resistance. In the case of the zero-field transition the value of the limiting resistance may be universal and very close to h/4e2, the quantum resistance for pairs. The experimental results on both the zero- and finite-field transitions will be reviewed and their implications for a particular theoretical picture, the dirty boson model, will be discussed. It has been argued that this model is relevant to the superconductor-insulator transitions.
GENERALIZATION OF STATISTICS FOR SEVERAL SPECIES OF IDENTICAL PARTICLES
Authors: ISAKOV SERGEI B.
Published: November 2004

We present a framework for treating the statistical mechanics of systems including several species of particles with a statistical interaction between particles of different species. The statistical interaction is assumed to occur only between particles with the same momentum. Generalization of fractional statistics in one dimension to the case of several species of particles is discussed.
TWO-IMPURITY ANDERSON MODEL: SOME EXACT RESULTS WITH FERMI LIQUID THEORY
Authors: SANTORO GIUSEPPE E. , GIULIANI GABRIELE F.
Published: November 2004

We present exact expressions for the conduction electron phase shifts for the two-impurity Anderson model in terms of the impurity Green functions. We show that, for the symmetric model, to all orders in the perturbation theory in U, the only allowed value of the phase shifts is π/2. It is also shown that, quite generally, a vanishing of the phase shifts (signaling a RKKY phase) must be associated with the development of a gap in the impurity single particle excitation spectrum. In the symmetric case this is in turn associated with a divergence of the linear coefficient of the heat capacity. The implications of these results on the physics of the transition from Kondo to RKKY phases are briefly discussed.
TEMPORAL CORRELATION OF NEUTRONS, ION BEAM, AND HIGH VOLTAGE PROBE SIGNALS IN A LOW ENERGY PLASMA FOCUS
Authors: ZAKAULLAH M. , AHMAD IMTIAZ , MURTAZA G. , SHAH ANWAR Z. , BEG M.M.
Published: November 2004

A simple, low inductance (~50 nH) capacitor bank is developed for plasma focus operation. The bank comprises three modules, each consisting of two 2µF, 40 kV capacitors along with a field distortion type pressurized sparkgap. The system is employed to investigate the temporal correlation of neutrons, ion beam, high voltage probe, and Rogowski coil signals. From a careful analysis of the data, the high voltage probe signal is found to coincide well with the Rogowski coil signal, whereas the ion beam and the neutron pulses are delayed by 20–30 nsec. These observations suggest that in low energy plasma foci, ion beam generation and neutron emission occur after the maximum compression has taken place and the pinch filament has started to break, most probably due to the onset of sausage type instability.
SURFACE MELTING AND SURFACE ROUGHENING OF Pb(110) STUDIED BY LOW ENERGY ION SCATTERING
Authors: SPELLER S. , SCHLEBERGER M. , FRANKE H. , MÜLLER C. , HEILAND W.
Published: November 2004

The Pb(110) surface undergoes two phase transitions. At about 400 K a roughening transition is observed. At 580 K, i.e. about 20 K below the bulk melting point, surface melting is found, The surface develops point defects at rather low temperatures. The roughening is connected with the generation of steps or the reduction of terrace size. There is also evidence for anisotropy of the roughening transition. Low energy ion scattering experiments in the temperature range from 160 to 590 K are used to study the structural changes of the Pb(110) surface.
CALCULATIONS OF THE INTERATOMIC CORRELATION MOMENTS IN A SIMPLE MODEL OF AN ANHARMONIC CRYSTAL
Authors: ZUBOV V. I. , PASCUAL M. F.
Published: November 2004

To study the interatomic correlations in anharmonic crystals we have used the correlative method of unsymmetrized self-consistent field (CUSF). The zeroth-order approximation of this method takes into account the main anharmonic terms but disregards the dynamical interatomic correlations at intermediate and long distances. With the aid of the first- and second-order perturbation theory we have derived the general expressions for quadratic correlations in two-dimensional models of crystals taking into account anharmonic terms up to the fourth order. Herewith we have constructed the corresponding diagrams. Correlations between the nearest, second, and third neighbors in square lattice have been calculated.
SIZE DEPENDENCE OF THE LONGITUDINAL OPTICAL AND SURFACE OPTICAL PHONON MODES IN CYLINDRICAL QUANTUM WIRES
Authors: ZHOU HAI-YANG , GU SHI-WEI
Published: November 2004

With the use of the classical macroscopic approach, we have derived the longitudinal optical (LO) and surface optical (SO) phonon modes in a cylindrical quantum wire (QW). The dispersion relation of the SO phonon modes in the QW is discussed explicitly. Having quantized the vibrational eigenmodes, we give the interaction Hamiltonian of the electron with the LO and SO phonon modes in QW.
FEATURES OF SET DYNAMICS IN ULTRASMALL SNS AND NSN DOUBLE JUNCTIONS
Authors: KRECH WOLFRAM , MÜLLER HEINZ-OLAF
Published: November 2004

The aim of this paper is to investigate the behavior of ultrasmall SNS and NSN double junctions at T = 0 in terms of a golden rule ansatz with regard to the normal conducting phase of the superconducting electrodes. The sensitivity of electrometers built from SNS and NSN single electron tunneling (SET) transistors is evaluated for T > 0 including a consideration of the shot noise behavior. Incoherent cotunneling is treated analytically in both SNS and NSN devices and a rough estimation of coherent cotunneling is done numerically in the case of SNS. The influence of a high impedance but ohmic environment is discussed. Emphasis is put on the case Δ < e2/[2(C1 + C2)] (with the capacitance C1,2 of the respective junction) and the effects of discrete states of the central electrode are neglected.
THE STAR SQUARE IN THE BAXTER–BAZHANOV MODEL AND THE STAR–TRIANGLE RELATION IN THE CHIRAL POTTS MODEL
Authors: HU ZHAN-NING
Published: November 2004

In this letter, the connection is found between the "star–square" relation in the Baxter–Bazhanov model and the "star–triangle" relation in the chiral Potts model, which means that the tetrahedron equation of the Baxter–Bazhanov model is a consequence of the latter. The four additional constraints in the tetrahedron equation given by Kashaev et al. hold naturally in respect to the spherical trigonometry parametrizations.
DYNAMICS OF QUANTUM CRITICALITY IN TWO DIMENSIONS
Authors: LU W. , WANG Y. J. , GONG C. D.
Published: November 2004

A scaling hypothesis of the local spin and charge dynamic susceptibility is proposed for two-dimensional antiferromagnetically correlated quantum systems, which interpolate between the antiferromagnetic insulator limit and the nearly antiferromagnetic metal limit. The characteristic energy is calculated self-consistently by the sum rule. The quantum-critical behavior in the vicinity of a zero-temperature phase transition is responsible for the anomalies of high-T c cuprates.
CHARGE TRANSPORT IN GERMANIUM-SUBSTITUTED MAGNESIUM FERRITES
Authors: MALIK MD. ABDUL , REDDY V. D. , REDDY P. VENUGOPAL , SAGAR D. R. , PRANKISHAN
Published: November 2004

Electrical conductivity (σ) and thermopower measurements have been carried out on some Mg 1+x Ge x Fe 2−2x O 4 (0 < x < 0.4) ferrite samples over a temperature range 300–700 K. Using the experimental values of Seebeck coefficient at various temperatures, the values of charge carrier concentration have been determined. On the basis of the temperature variation of charge carrier mobility, the conduction mechanism in these ferrites has been discussed.
RECURRENCE FORMULA FOR THERMOCURRENT OF DISORDERED SYSTEMS
Authors: SKAL ASYA S.
Published: November 2004

A recurrence formula for thermocurrent of macroscopically inhomogeneous material in sequence for α is obtained.  = E−1ʃα(r)(j0(r) · ∇Tk−1(r))dV, where α(r) is a local value of Seebeck coefficient, E is the electric field, and T(r) is a local temperature. This formula gives the contributions of all orders of Seebeck coefficient in thermocurrent.
GROWTH KINETICS IN THE Φ6N-COMPONENT MODEL: NONCONSERVED ORDER PARAMETER
Authors: CORBERI F. , MARCONI U. MARINI BETTOLO
Published: November 2004

The dynamics of a system with a nonconserved N-component order parameter described by a Ginzburg–Landau free energy functional containing a sixth order nonlinearity is discussed in the spherical limit. The model displays a richer behavior than the well-studied Φ4 case. In particular it shows interesting properties regarding metastability, a feature which is absent in the spherical Φ4 model.
LANDAU LEVEL GAP REDUCTION AT ABRUPT EDGES
Authors: BARTOŠ I. , ROSENSTEIN B.
Published: November 2004

For an electron localized near a finite rectangular step potential under strong magnetic field we found a profound local reduction of the gap between neighboring Landau levels.1,2 We investigate under what conditions the effect persists when the barrier gets smoother. The conclusion is that to get a substantial gap reduction the barrier gradient has to be larger than ħw c /a L (a L is the magnetic length). The sensitivity of the gap reduction is illustrated using tilted and multiple step barriers and finite stripe configurations.
INFLUENCE OF THE COUNTER-ROTATING TERMS ON THE RABI OSCILLATIONS AND SQUEEZING IN THE JAYNES-CUMMINGS MODEL WITH CAVITY LOSSES FOR INITIAL COHERENT FIELDS
Authors: SEKE J.
Published: November 2004

The significance of the counter-rotating terms in the Jaynes-Cummings model with cavity losses is demonstrated. Numerical results for the time evolution of the atomic population inversion, dipole moment, and atomic and field squeezing parameters for an initial coherent field are presented for different cavity dampings. In low-Q cavities the counter-rotating terms lead to the appearance of new steady states.
NONLINEAR MOBILITY IN A SUPERCONDUCTING TUNNEL JUNCTION INVOLVING VARIATIONAL WAVE FUNCTIONS
Authors: EXTREMERA A.
Published: November 2004

We consider the effect of dissipation on the nonlinear mobility in a superconducting tunnel junction. Using a variational approach, the critical mobility crucially depends on the coupling to the ohmic bath. At ultrasmall capacitances, good agreement is found with decay rates diagrams. The current model could be developed in other contexts, such as that of a ferroelectric capacitor, as proposed by Widom and Clark (Phys. Rev.B30, 1205 (1984)).
OHMIC RESISTIVITY AND NONLINEAR TRANSPORT OF CHARGE DENSITY WAVES IN BLUE BRONZES K0.3MoO3
Authors: MING-LIANG TIAN , ZHI-QIANG MAO , RUI-PING WANG , YU-HENG ZHANG
Published: November 2004

Ohmic resistivity and nonlinear transport properties of sliding charge density wave (CDW) conduction in blue bronze K0.3MoO3 were measured. It is found that at about 183 K the sample undergoes a metal-to-semiconductor transition, i.e. Peierls transition. In semiconducting CDW state, the estimated activation energies εg in the temperature ranges of 77–135 and 150–180 K are, respectively, about 0.033 and 0.051 eV by the measurements of ohmic resistivity, where the field is below the depinning field VT of CDW motion. Above VT, the analytic form of nonlinear current of sliding CDW in a moderate current range fits the power law relation, i.e. I CDW ∝(V/V T −1)α; the exponent a is not a constant, but relies on temperatures. In high field range, the analytic form of nonlinear current of the CDW motion deviates from the power law relation, but it can be described by the microscopic model including the internal degrees of freedom proposed by Sneddon et al., i.e. I CDW =σ n E+CE1/2, with σ n being the conductivity of normal carriers and C a constant.
THE INFLUENCE OF JOSEPHSON JUNCTIONS ON THE DYNAMICAL CURRENT-VOLTAGE ANOMALIES IN CERAMIC SUPERCONDUCTORS
Authors: SOSNOWSKI J.
Published: November 2004

The influence of Josephson junction array on the dynamical current-voltage anomalies and magnetic properties of high temperature ceramic superconductors is analyzed. The influence of vortices penetrating the junction regions on the macroscopic current flowing through the sample is considered. In the case of zero transport current the existence of vortices modifies the magnetic field dependence of the screening currents and such magnetic properties as the shape of magnetization curves. In the case of transport current flow the existence of junctions may lead to a new critical state approach the consequences of which are anomalies of the dynamical current-voltage characteristics. Comparison of the theoretical model predictions with experimental data measured on high temperature ceramics of various composition is made.
SPATIOTEMPORAL PATTERNS IN LANGMUIR PLASMAS
Authors: ZHOU CANGTAO , HE X.T.
Published: November 2004

The constitutions of the phase space, stochasticity, and the complicated patterns of Langmuir fields are investigated in terms of a two-dimensional cubic-quintic nonlinear Schrödinger equation. The numerical results obviously illustrate that the quintic non-linearity leads to the production of the complicated patterns. The mechanism to form these spatial patterns is also analyzed by measuring the spectrum of energy in Fourier space. It is shown that the complicated patterns are associated with the complexity of trajectory in phase space and the stochastic partition of energy in Fourier modes.
ELECTRONIC WEAK LOCALIZATION AND SUPERCONDUCTIVITY FOR YBa2Cu3−xAlxOy (x=0−0.4) SYSTEMS: A POSITRON STUDY
Authors: JINCANG ZHANG , GUOSHENG CHENG , SHIXUN CAO , FENGQI LIU , JUNZHENG LIU , JIAXIANG SHANG
Published: November 2004

In this paper, we present the positron lifetime data in high T c cuprate perovskite YBa 2 Cu 3−x Al x O y (x=0−0.4) systems. A significant Al substitution dependence of the positron lifetime parameters was observed, and the local electron density ne and defect concentration C d were also calculated as a function of Al substitution x. The results show that at low doping concentration, x≤0.15, both n e and C d exhibit a large change and then reach a limit value of saturation or a peak value above x=0.15 which corresponds just right to the known structural transition from orthorhombic to tetragonal phase. Here, the decrease in n e can be interpreted by weak electronic localization in Cu-O chains. The effect of n e on superconductivity and the mechanisms of positron annihilation were also discussed.
QUANTUM HALL EFFECT AND BERRY PHASE
Authors: BANERJEE DIPTI , BANDYOPADHYAY PRATUL
Published: November 2004

It is shown here that a particle in an intense magnetic field may acquire the Berry phase and the topological features associated with this phase may be taken to be responsible for both the integrally and fractionally quantized Hall effect. The two different manifestations of quantum Hall effect have been realized in a unified scheme where the electrons associated with the fractional quantum Hall effect are found to be in an excited state having higher angular momentum.
UNIFORM CONVERGENCE BOUNDS FOR LEARNING FROM EXAMPLES
Authors: ENGEL A.
Published: November 2004

Basic notions of learning from examples in feed-forward neural networks are reviewed with special emphasis on the relation between the different approaches. First classical results of mathematical statistics on uniform bounds for the convergence of the learning error to the generalization error are discussed from a physical point of view. Recent work of statistical mechanics on the generalization ability of large networks of formal neurons is shown to reproduce and extend these results. In particular for simple architectures the tightness of the convergence bounds as well as the relation between the typical and the worst case performance can be determined in the thermodynamic limit. Several interesting questions remain open.
ON THE SOLVABILITY OF THE BOUNDARY-VALUE PROBLEM FOR THE ELASTIC BEAM WITH ATTACHED LOAD
Authors: DALSEN MARIÉ GROBBELAAR-VAN
Published: November 2004

When a flexible rectangular homogeneous beam, which is horizontal in equilibrium state, has an end rigidly fixed while a load is attached to the other end, the transverse vibrations of the beam are described by the elastic beam equation together with, amongst others, a dynamic boundary condition at that end of the beam to which the load is attached. In this paper we introduce various types of energy dissipation for this problem, viz. damping of Kelvin-Voigt type as well as structural damping. The resulting boundary-value problems are studied within the framework of the abstract theories of B-evolutions and fractional powers of a closed pair of operators by formulating an abstract evolution problem in the paired space X1×X, with X a Hilbert space and X1 continuously imbedded in X. This approach yields a unique solution in the strong sense which exhibits exponential decay as time tends to infinity for any initial displacement in X1 and any initial velocity in X.
STEADY FLOWS OF A VISCOUS INCOMPRESSIBLE FLUID IN A POROUS HALF-SPACE
Authors: PASSERINI ARIANNA
Published: November 2004

In this paper we prove the existence and asymptotic behavior of solutions to the equations describing the steady motion of a viscous incompressible fluid in a porous half-space. The results are compared with those already known for the Navier-Stokes model and we find, in particular, that the behavior at large distances is strongly different depending on the value of the incoming flux through the boundary.
VACUUM INSTABILITY INDUCED BY HORIZONS
Authors: BROUT R.
Published: November 2004

The tunneling mechanism for producing particles in the presence of horizons is illustrated in three examples:

(i) Production of charged pairs in a static E field,

(ii) Thermal excitation of an accelerating system,

(iii) Black hole evaporation.

The thermodynamics of black hole evaporation is discussed in detail.
CANONICAL TREATMENT OF COSET SPACE SIGMA MODELS
Authors: MATSCHULL H.-J. , NICOLAI H.
Published: November 2004

The canonical treatment and quantization of non-linear coset space sigma models are discussed.
SOLUTION TO 2+1 GRAVITY IN DREIBEIN FORMALISM
Authors: UNRUH W.G.
Published: November 2004

This paper outlines the reduction of the dreibein formalism of 2+1 General Relativity to the dynamical degrees of freedom for a genus 2 (and by extension for an arbitrary genus) two space. The resulting dynamical variables of the reduced theory are global holonomies and are constants of the motion of the original theory. The relation to geometry and closed timelike curves is briefly described.
CONSISTENT INTERACTIONS BETWEEN GAUGE FIELDS AND LOCAL BRST COHOMOLOGY: THE EXAMPLE OF YANG-MILLS MODELS
Authors: BARNICH G. , HENNEAUX M. , TATAR R.
Published: November 2004

Recent results on the cohomological reformulation of the problem of consistent interactions between gauge fields are illustrated in the case of the Yang-Mills models. By evaluating the local BRST cohomology through descent equation techniques, it is shown (i) that there is a unique local, Poincaré invariant cubic vertex for free gauge vector fields which preserves the number of gauge symmetries to first order in the coupling constant; and (ii) that consistency to second order in the coupling constant requires the structure constants appearing in the cubic vertex to fulfill the Jacobi identity. The known uniqueness of the Yang-Mills coupling is therefore rederived through cohomological arguments.
THICK EINSTEIN SHELLS AS “HEAT" BATHS FOR BLACK HOLES
Authors: COMER G.L.
Published: November 2004

We discuss the significance of the “heat” bath for black hole thermodynamics and how to represent it as a thick Einstein shell.
TEST-PARTICLE MOTION IN A CLASSICAL RELATIVISTIC PLASMA
Authors: GARIEL J. , GOTTAL Ph. de
Published: November 2004

Starting from the covariant relativistic Balescu-Lenard (or Klinontovich-Silin) equation we derive a classical relativistic Fokker-Plank equation for a test-particle in a stable isotropic plasma with collective effects. The geometrical form of the diffusion tensor and friction 4-vector is given, and their behaviour is analyzed for various dynamical conditions: non relativistic and ultrarelativistic plasma. A H-theorem is proven. The main feature of the collective effects is that longitudinal oscillations of plasma appear, whereas transversal ones (Cerenkov effect) do not. A limit value of the critical velocity of the test-particle from which the plasm oscillations appear is found.
MATRIX MODELS AND INTEGRABLE C<1 OPEN STRING THEORIES
Authors: HOUART LAURENT
Published: November 2004

We study in the double scaling limit the two-matrix model which represents the sum over closed and open random surfaces coupled to an Ising model. The boundary conditions are characterized by the fact that the Ising spins sitting at the vertices of the boundaries are all in the same state. We obtain the string equation.
COSMOLOGICAL MODELS IN THE R2 THEORY OF GRAVITY
Authors: SPINDEL PHILIPPE
Published: November 2004

I summarize some results obtained in the framework of the R2 theory of gravity: the general Bianchi-I solution in arbitrary dimensions and the description of the asymptotic behaviour of generic Bianchi-IX models in 3+1 dimensions.
BARYOGENESIS AND LOW ENERGY CP PHENOMENOLOGY
Authors: TYTGAT MICHEL
Published: November 2004

A mechanism for baryogenesis is used in the framework of a left-right extension of the standard model. In this model the baryon number of the universe is related to other CP violating observables and in particular to the parameter ε describing mixing in the [Formula: see text] system.
NEUTRINOS FROM SUPERNOVAE
Authors: KIEŁCZEWSKA DANUTA
Published: November 2004

The historic detection of neutrinos from supernova SN1987A demonstrated that they are an invaluable source of information about neutrino properties and the dynamics of gravitational stellar collapse. A number of experiments are currently being prepared for the next detection of the supernova neutrino burst. This article reviews the data of SN1987A, the puzzles they presented and the lessons about neutrino properties that they provided. A special emphasis is put on the preparation for future detections and evaluation of an improvement in understanding basic neutrino properties that can be achieved.
ASSOCIATED LENGTH AND INFLATION IN QUANTUM MECHANICS WITH GRAVITATIONAL SELF-INTERACTION
Authors: PETROV A.N. , POPOVA A.D.
Published: November 2004

Earlier, quantum mechanics with gravitational self-interaction was constructed which, on the one hand, maximally resembles classical field theory and, on the other hand, admits a probability interpretation. The main feature of the constructed theory is the presence of some characteristic length associated with each particle. Here, in the framework of this theory, the cosmological inflation solution is considered together with restrictions following from the problems of horizon and flatness. An analysis gives the admissible values of the parameters involved: the associated length of inflatons and their number factorized by a parameter characterizing initial data for their wave functions.
ON THE ORIGIN OF THE COSMIC MAGNETIC FIELD
Authors: POLLOCK M.D.
Published: November 2004

It is shown how a cosmic magnetic field Bc can arise in the dimensionally reduced, heterotic superstring theory, via the logarithmic variation with temperature of the string gauge coupling parameter, assuming the ansatz where the asantaz ḡ≡0(α1α2α3)1/6, where the αi are the fine-structure constants of the electroweak and strong interactions. If [Formula: see text], where H0=100h km s −1 Mpc −1 is the Hubble parameter and s≫1 is a constant, then [Formula: see text]. Thus, for example, if s=3×103, then B c ≈3×10−6 G .
LOCAL SUPERSYMMETRY IN ONE-LOOP QUANTUM COSMOLOGY
Authors: ESPOSITO GIAMPIERO
Published: November 2004

The contribution of physical degrees of freedom to the one-loop amplitudes of Euclidean supergravity is here evaluated in the case of flat Euclidean backgrounds bounded by a three-sphere, recently considered in perturbative quantum cosmology. In Euclidean supergravity, the spin-[Formula: see text] potential has the pair of independent spatial components [Formula: see text]. Massless gravitinos are here subject to the following local boundary conditions on [Formula: see text], where [Formula: see text] is the Euclidean normal to the three-sphere boundary. The physical degrees of freedom (denoted by PDF) are picked out imposing the supersymmetry constraints and choosing the gauge condition [Formula: see text], [Formula: see text]. These local boundary conditions are then found to imply the eigenvalue condition [Jn + 2 (E)]2 - [Jn + 3(E)]2 = 0, ∀ n ≥ 0, with degeneracy (n+4)(n+1). One can thus apply again a zeta-function technique previously used for massless spin-½ fields. The PDF contribution to the full ζ(0) value is found to be [Formula: see text]. Remarkably, for the massless gravitino field the PDF method and local boundary conditions lead to a result for ζ(0) which is equal to the PDF value one obtains using spectral boundary conditions on S3.
MULTIDIMENSIONAL COSMOLOGY WITH m-COMPONENT PERFECT FLUID
Authors: IVASHCHUK V.D. , MELNIKOV V.N.
Published: November 2004

A cosmological model describing the evolution of n Einstein spaces (n>1) with m- component perfect-fluid matter is considered. When all spaces are Ricci-flat and for any α-th component the pressures in all spaces are proportional to the density: [Formula: see text], the Einstein and Wheeler-DeWitt equations are integrated in the cases: (i) m=1, for all [Formula: see text]; (ii) m>1, for some special sets of [Formula: see text]. For m=1 the quantum wormhole solutions are also obtained.
SYSTEMATICS OF SPIRAL ROTATION FROM TIDAL TORQUING
Authors: FLORES RICARDO
Published: November 2004

We discuss the disk galaxy rotation curves expected in the tidal torque theory of angular momentum, in which the protogalactic angular momentum is not universal. If the fraction of dissipative material in a collapsed protogalaxy is approximately 5%, the value suggested by nucleosynthesis constraints if it is a universal constant, the amount of variation expected in the angular momentum (a) leads to rotation curves for bright galaxies whose systematics are much like those recently pointed out by Casertano and van Gorkom, and (b) the mass inside a “Holmberg” radius of 4.5 disk scale lengths shows a spread of values consistent with observations.
DARK MATTER IN SPIRAL HALOS AND THE HALO MASS FUNCTION
Authors: ASHMAN KEITH M. , SALUCCI PAOLO , PERSIC MASSIMO
Published: November 2004

Evidence that low-luminosity spirals have a higher dark matter fraction than their high-luminosity counterparts is discussed. The empirical correlation between dark matter fraction and luminosity is used, in conjunction with the galaxy luminosity function of spirals, to derive the dark halo mass function of these galaxies. The mass function is shown to be consistent with hierarchical clustering models of galaxy formation. This contrasts with previous results based on the assumption of a constant mass-to-light ratio for all spirals, which predict too many low-luminosity galaxies.
DEUTERON-NUCLEUS INTERACTION AT INTERMEDIATE ENERGIES
Authors: BEREZHNOY YU. A. , KORDA V. YU.
Published: November 2004

The deuteron-nucleus interaction has been studied in the approximation where the deuteron radius and the nuclear surface diffuseness are small compared with the nuclear radius. The closed formulae have been derived for the integrated cross-sections of different deuteron-nucleus interaction processes and for differential cross-sections of the deuteron elastic scattering and the deuteron inelastic scattering with excitation of the low lying vibrational states of nuclei. It is shown that the allowance for nuclear surface diffuseness substantially influences the values of the different deuteron-nucleus reaction cross-sections.
CONTRIBUTION OF THE PARITY DEPENDENT POTENTIAL IN HEAVY ION TRANSFER REACTIONS
Authors: OSMAN AHMED , FARRA A.A.
Published: November 2004

The theory of heavy ion reactions with particle transfer is considered in the framework of the exact finite-range distorted wave Born approximation (EFR-DWBA). Modified Woods-Saxon potentials which include a parity dependent interaction and an angular momentum absorptive term have been used as the ion-ion interactions in the initial and final channels. The bound state interactions are represented by nucleus-nucleus inter-actions which include repulsive and attractive Yukawa type components. The present numerical calculations of the differential cross-sections are in good agreement with the experimental measurements. The distorting parity dependent potentials are found very important in reproducing the cross-sections at backward as well as at intermediate angles. The obtained extracted values of the spectroscopic factors are reasonable.
MULTIBARYON SOLUTIONS OF A CHIRAL QUARK-MESON MODEL
Authors: SEGAR J. , SRIPRIYA M. , SRIRAM M.S.
Published: November 2004

We consider multibaryon configurations in a SU(2) quark soliton model based on chiral invariant quark-meson couplings. We compute the energy of interaction between two nucleons by considering configurations which correspond to two B=1 solitons separated by a fixed distance. The gross features of the inter-nucleon potential are reproduced. We also find cylindrically symmetric, classically stable soliton solutions with B=2, 3 and 4. The energy distributions corresponding to these solutions are toroidal in nature. The results closely parallel the Skyrme-model calculations.
Involvement of calcium-sensing receptor in osteoblastic differentiation of mouse MC3T3-E1 cells
Authors: Yamauchi Mika , Yamaguchi Toru , Kaji Hiroshi , Sugimoto Toshitsugu , Chihara Kazuo
Published: November 2004

We have previously shown that the extracellular calcium-sensing receptor (CaR) is expressed in various bone marrow-derived cell lines and plays an important role in stimulating their proliferation and chemotaxis. It has also been reported that the CaR modulates matrix production and mineralization in chondrogenic cells. However, it remains unclear whether the CaR plays any role in regulating osteoblast differentiation. In this study, we found that mineralization of the mouse osteoblastic MC3T3-E1 cells was increased when the cells were exposed to high calcium (2.8 and 3.8 mM) or a specific CaR activator, NPS-R467 (1 and 3 μM). Next, we stably transfected MC3T3-E1 cells with either a CaR antisense vector (AS clone) or a vector containing the inactivating R185Q variant of the CaR (DN clone) that has previously been shown to exert a dominant negative action. Alkaline phosphatase activities were decreased compared with controls in both the AS and DN clones. However, the levels of type I procollagen and osteopontin mRNA in the AS clone, as detected by Northern blotting, were almost the same as in the controls. On the other hand, the expression of osteocalcin, which is expressed at a later stage of osteoblastic differentiation, was significantly reduced in both the AS and DN clones. Mineralization was also decreased in both clones. In conclusion, this study showed that the abolition of CaR function results in diminishing alkaline phosphatase activity, osteocalcin expression, and mineralization in mouse osteoblastic cells. This suggests that the CaR may be involved in osteoblastic differentiation.
Responses of cerebral arterioles to ADP: eNOS-dependent and eNOS-independent mechanisms
Authors: Faraci Frank M. , Lynch Cynthia , Lamping Kathryn G.
Published: November 2004

ADP mediates platelet-induced relaxation of blood vessels and may function as an important intercellular signaling molecule in the brain. We used pharmacological and genetic approaches to examine mechanisms that mediate responses of cerebral arterioles to ADP, including the role of endothelial nitric oxide synthase (eNOS). We examined responses of cerebral arterioles (control diameter ∼30 μm) in anesthetized wild-type (WT, eNOS+/+) and eNOS-deficient (eNOS−/−) mice using a cranial window. In WT mice, local application of ADP produced vasodilation that was not altered by indomethacin but was reduced by ∼50% by NG-nitro-l-arginine (l-NNA) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (inhibitors of NOS and soluble guanylate cyclase, respectively). In eNOS−/− mice, responses to ADP were largely preserved, and a significant component of the response was resistant to l-NNA (a finding similar to that in WT mice treated with l-NNA). In the absence of l-NNA, responses to ADP were markedly reduced by charybdotoxin plus apamin [inhibitors of Ca2+-dependent K+ channels and responses mediated by endothelium-derived hyperpolarizing factor (EDHF)] in both WT and eNOS−/− mice. Thus pharmacological and genetic evidence suggests that a significant portion of the response to ADP in cerebral microvessels is mediated by a mechanism independent of eNOS. The eNOS-independent mechanism is functional in the absence of inhibited eNOS and most likely is mediated by an EDHF.
Stretch induces upregulation of key tyrosine kinase receptors in microvascular endothelial cells
Authors: Zheng Wei , Christensen Lance P. , Tomanek Robert J.
Published: November 2004

We previously demonstrated that cyclic stretch of cardiac myocytes activates paracrine signaling via vascular endothelial growth factor (VEGF) leading to angiogenesis. The present study tested the hypothesis that cyclic stretch upregulates tyrosine kinase receptors in rat coronary microvascular endothelial cells (RCMEC) and human umbilical vein endothelial cells (HUVEC). VEGF receptor-2 (Flk-1) protein levels increased in HUVEC and RCMEC in a time-dependent manner, but the increase occurred much earlier in RCMEC than in HUVEC. The enhancement of Flk-1 protein level was not inhibited by addition of VEGF neutralizing antibodies, indicating that VEGF is not involved in stretch-induced Flk-1 expression. VEGF receptor-1 (Flt-1) protein and mRNA were not changed by stretch. However, Tie-2 and Tie-1 protein levels increased in RCMEC. Angiopoietin-1 and -2, the ligands for Tie-2, increased in cardiac myocytes subjected to cyclic stretch but were not affected by stretch in endothelial cells (EC). Stretch or incubation of RCMEC with VEGF increased cell proliferation moderately, whereas stretch + VEGF had an additive effect on proliferation. Mechanical stretch induces upregulation of the key tyrosine kinase receptors Flk-1, Tie-2, and Tie-1 in vascular EC, which underlies the increase in sensitivity of EC to growth factors and, therefore, facilitates angiogenesis. These in vitro findings support the concept that stretch of cardiac myocytes and EC plays a key role in coronary angiogenesis.
Combined angiotensin receptor blocker and ACE inhibitor on myocardial fibrosis and left ventricular stiffness in dogs with heart failure
Authors: Funabiki Kaoru , Onishi Katsuya , Dohi Kaoru , Koji Takafumi , Imanaka-Yoshida Kyoko , Ito Masaaki , Wada Hideo , Isaka Naoki , Nobori Tsutomu , Nakano Takeshi
Published: November 2004

Angiotensin receptor blocker (ARB) and angiotensin-converting enzyme (ACE) inhibitor (ACEI) each act in a different manner to prevent myocardial fibrosis and left ventricular (LV) stiffness in animals with pathways in the heart for generating ANG II as well as ACE. A model of pacing-induced congestive heart failure (CHF) was used to test the central hypothesis that ARB + ACEI prevents myocardial fibrosis and decreases LV stiffness to a greater extent than ARB or ACEI alone. Thirty-five dogs were assigned to the following treatment protocols on the 8th day of a 4-wk pacing schedule: 1) rapid ventricular pacing, 2) ARB (candesartan cilexetil, 1.5 mg·kg−1·day−1) with pacing, 3) ACEI (enalapril, 1.9 mg·kg−1·day−1) with pacing, 4) ARB (candesartan cilexetil, 0.75 mg·kg−1·day−1) + ACEI (enalapril, 0.95 mg·kg−1·day−1) with pacing, and 5) sham operation. The LV stiffness coefficient was significantly increased after rapid pacing but was significantly lower with ARB + ACEI than with ARB or ACEI alone. The collagen volume fraction and mRNA levels of collagen I and III, which were increased by rapid pacing, were significantly lower with ARB + ACEI than with ARB or ACEI alone. Thus ARB + ACEI prevents myocardial fibrosis and decreases LV stiffness during the progression of CHF compared with ARB or ACEI alone.
Activation of dopamine D1-like receptors induces acute internalization of the renal Na+/phosphate cotransporter NaPi-IIa in mouse kidney and OK cells
Authors: Bacic Desa , Capuano Paola , Baum Michel , Zhang Jianning , Stange Gerti , Biber Jürg , Kaissling Brigitte , Moe Orson W. , Wagner Carsten A. , Murer Heini
Published: November 2004

The Na+/phosphate cotransporter NaPi-IIa (SLC34A1) is the major transporter mediating the reabsorption of Piin the proximal tubule. Expression and activity of NaPi-IIa is regulated by several factors, including parathyroid hormone, dopamine, metabolic acidosis, and dietary Piintake. Dopamine induces natriuresis and phosphaturia in vivo, and its actions on several Na+-transporting systems such as NHE3 and Na+-K+-ATPase have been investigated in detail. Using freshly isolated mouse kidney slices, perfused proximal tubules, and cultured renal epithelial cells, we examined the acute effects of dopamine on NaPi-IIa expression and localization. Incubation of isolated kidney slices with the selective D1-like receptor agonists fenoldopam (10 μM) and SKF-38393 (10 μM) for 1 h induced NaPi-IIa internalization and reduced expression of NaPi-IIa in the brush border membrane (BBM). The D2-like selective agonist quinpirole (1 μM) had no effect. The D1and D2agonists did not affect the renal Na+/sulfate cotransporter NaSi in the BBM of the proximal tubule. Studies with isolated perfused proximal tubules demonstrated that activation of luminal, but not basolateral, D1-like receptors caused NaPi-IIa internalization. In kidney slices, inhibition of PKC (1 μM chelerythrine) or ERK1/2 (20 μM PD-098089) pathways did not prevent the fenoldopam-induced internalization. Inhibition with the PKA blocker H-89 (10 μM) abolished the effect of fenoldopam. Immunoblot demonstrated a reduction of NaPi-IIa protein in BBMs from kidney slices treated with fenoldopam. Incubation of opossum kidney cells transfected with NaPi-IIa-green fluorescent protein chimera shifted fluorescence from the apical membrane to an intracellular pool. In summary, dopamine induces internalization of NaPi-IIa by activation of luminal D1-like receptors, an effect that is mediated by PKA.
Mixed quasi invex equilibrium problems
Authors: Noor Muhammad Aslam
Published: November 2004

We introduce a new class of equilibrium problems, known as
mixed quasi invex equilibrium (or
equilibrium-like) problems. This class of invex
equilibrium problems includes equilibrium
problems, variational inequalities, and
variational‐like inequalities as special cases. Several iterative
schemes for solving invex equilibrium problems are suggested and
analyzed using the auxiliary principle technique. It is shown
that the convergence of these iterative schemes requires either
pseudomonotonicity or partially relaxed strong monotonicity,
which are weaker conditions than the previous ones. As special
cases, we also obtained the correct forms of the algorithms for
solving variational‐like inequalities, which have been considered
in the setting of convexity. In fact, our results represent
significant and important refinements of the previously known
results.
Antieigenvalue inequalities in operator theory
Authors: Seddighin Morteza
Published: November 2004

We will prove some inequalities among trigonometric quantities of
two and three operators. In particular, we will establish an
inequality among joint trigonometric quantities of two operators
and trigonometric quantities of each operator. As a corollary, we
will find an upper bound and a lower bound for the total joint
antieigenvalue of two positive operators in terms of the smallest
and largest eigenvalues of these operators.