July 1999 arXiv papers — page 21

Thibault Damour, Gabriele Veneziano

The configuration of typical highly excited (M >> M_s ~ (alpha')^{-1/2}) string states is considered as the string coupling g is adiabatically increased. The size distribution of very massive single string states is studied and the mass shift, due to long-range gravitational, dilatonic and axionic attraction, is estimated. By combining the two effects, i

R. Quian Quiroga, J. Arnhold, P. Grassberger

We test recent claims that causal (driver/response) relationships can be deduced from interdependencies between simultaneously measured time series. We apply two recently proposed interdependence measures which should give similar results as cross predictabilities used by previous authors. The systems which we study are asymmetrically coupled simple models (

Federico Corberi, Mario Nicodemi, Marina Piccioni, Antonio Coniglio

We introduce a schematic non-linear diffusion model where density fluctuations induce a rich out of equilibrium dynamics. The properties of the model are studied by numerical simulations and analytically in a mean field approximation. At low temperatures and high densities we find a long off-equilibrium glassy region, where the system evolves out of an initi

Yasuhiro Sekino, Tamiaki Yoneya

Guided by the generalized conformal symmetry, we investigate the extension of AdS-CFT correspondence to the matrix model of D-particles in the large N limit. We perform a complete harmonic analysis of the bosonic linearized fluctuations around a heavy D-particle background in IIA supergravity in 10 dimensions and find that the spectrum precisely agrees with

Eirik Fossgaard

We propose alternative discriminant measures for selecting the best basis among a large collection of orthonormal bases for classification purposes. A generalization of the Local Discriminant Basis Algorithm of Saito and Coifman is constructed. The success of these new methods is evaluated and compared to earlier methods in experiments.

J. Rychen, T. Ihn, P. Studerus, A. Herrmann

Piezoelectric quartz tuning forks are investigated in view of their use as force sensors in dynamic mode scanning probe microscopy at temperatures down to 1.5 K and in magnetic fields up to 8 T. The mechanical properties of the forks are extracted from the frequency dependent admittance and simultaneous interferometric measurements. The performance of the fo

Shogo Tanimura, Toshihiro Iwai

This paper deals with a general method for the reduction of quantum systems with symmetry. For a Riemannian manifold M admitting a compact Lie group G as an isometry group, the quotient space Q = M/G is not a smooth manifold in general but stratified into a collection of smooth manifolds of various dimensions. If the action of the compact group G is free, M

A. Carlini, A. Hosoya

We present a quantum version of the classical probabilistic algorithms $\grave{a}$ la Rabin. The quantum algorithm is based on the essential use of Grover's operator for the quantum search of a database and of Shor's Fourier transform for extracting the periodicity of a function, and their combined use in the counting algorithm originally introduced

Holger F. Hofmann

Even though measurement results obtained in the real world are generally both noisy and continuous, quantum measurement theory tends to emphasize the ideal limit of perfect precision and quantized measurement results. In this article, a more general concept of noisy measurements is applied to investigate the role of quantum noise in the measurement process.

Andreas Jaster

We investigate the dynamic relaxation for SU(2) gauge theory at finite temperatures in (3+1) dimensions. Using the Hybrid Monte Carlo algorithm, we examine the time dependence of the system in the short-time regime. Starting from the ordered state, the critical exponents beta, nu and z are calculated from the power law behaviour of the Polyakov loop and the

Norbert Schorghofer

We study statistical properties of two-dimensional turbulent flows. Three systems are considered: the Navier-Stokes equation, surface quasi-geostrophic flow, and a model equation for thermal convection in the Earth's mantle. Direct numerical simulations are used to determine 1-point fluctuation properties. Comparative study shows universality of probabil

John Crisp, Marcelo Laca

The graph product of a family of groups lies somewhere between their direct and free products, with the graph determining which pairs of groups commute and which do not. We show that the graph product of quasi-lattice ordered groups is quasi-lattice ordered, and, when the underlying groups are amenable, that it satisfies Nica's amenability condition for

Peter Loeber

This paper is on identification of classical information by the use of quantum channels. We focus on simultaneous ID codes which use measurements being useful to identify an arbitrary message. We give a direct and a converse part of the appropriate coding theorem.

R. Srikanth

We propose a thought experiment for classical superluminal signal transmission based on the quantum nonlocal influence of photons on their momentum entangled EPR twins. The signal sender measures either position or momentum of particles in a pure ensemble of the entangled pairs, leaving their twins as localized particles or plane waves. The signal receiver d

B. Crosignani, P. Di Porto

We consider an isolated gaseous system, divided in two parts by an adiabatic movable frictionless internal wall undergoing Brownian motion. We show how this kind of motion can lead to a substantial decrease of the system entropy. This surprising result does not violate Boltzmann's H-theorem since the molecular chaos assumption underlying H-theorem is not

D. Kharzeev, R. L. Thews

We use dispersion relations to reconstruct, in a model-independent way, the formation dynamics of heavy quarkonium from the experimental data on e+ e- annihilation to Q-bar Q. We extract a distribution of formation times with a mean value for the J/psi, tau{J/psi} = 0.44 fm; and for the Upsilon, tau{Upsilon} = 0.32 fm. The corresponding widths of these distr

T. Barnes

In this contribution I discuss prospects for photoproducing hybrid mesons at CEBAF, based on recent model results and experimental indications of possible hybrids. One excellent opportunity appears to be a search for the I=1, JPC=2+-, neutral "(b2)o" hybrid in (a2 pi)o through diffractive photoproduction. Other notable possibilities accessible throug

V. G. Kartavenko, A. Sandulescu, W. Greiner

Nonlinear excitations of nuclear density are considered in the framework of semiclassical nonlinear nuclear hydrodynamics. Possible types of stationary nonlinear waves in nuclear media are analysed using Nonlinear Schroedinger equation of fifth order and classified using a simple mechanical picture. It is shown that a rich spectrum of nonlinear oscillations

Bin Zhang, C. M. Ko, Bao-An Li, Ziwei Lin

To study heavy ion collisions at energies available from the Relativistic Heavy Ion Collider, we have developed a multi-phase transport model that includes both initial partonic and final hadronic interactions. Specifically, the parton cascade model ZPC, which uses as input the parton distribution from the HIJING model, is extended to include the quark-gluon

M. Matsuo, T. Døssing, B. Herskind, S. Leoni

The intrinsic width of (multiparticle-multihole) compound states is an elusive quantity, of difficult direct access, as it is masked by damping mechanisms which control the collective response of nuclei. Through microscopic cranked shell model calculations, it is found that the strength function associated with two-dimensional gamma-coincidence spectra arisi

C. R. Morton, A. C. Berriman, M. Dasgupta, D. J. Hinde

Analyses using simplified coupled-channels models have been unable to describe the shape of the previously measured fusion barrier distribution for the doubly magic $^{16}$O+$^{208}$Pb system. This problem was investigated by re-measuring the fission excitation function for $^{16}$O+$^{208}$Pb with improved accuracy and performing more exact coupled-channels

Nigel Hitchin

These notes consist of a study of special Lagrangian submanifolds of Calabi-Yau manifolds and their moduli spaces. The particular case of three dimensions, important in string theory, allows us to introduce the notion of gerbes. These offer an appropriate language for describing many significant features of the Strominger-Yau-Zaslow approach to mirror symmet

Octavian Cornea

Flow type suspension and homotopy suspension agree for attractor-repellor homotopy data.The connection maps associated in Conley index theory to an attractor-repellor decomposition with respect to the direct flow and its inverse are Spanier-Whitehead duals in the stably parallelizable context and are duals modulo a certain Thom construction in general.

Igor Rivin

We study the moduli space of euclidean structures with cone points on a surface, and describe a decomposition into cells each of which corresponds to a given combinatorial type of Delaunay tessellation. We use some of the ideas to study hyperbolic structures on three-dimensional manifolds

Stefaan Vaes, Alfons Van Daele

In this paper we introduce the notion of a Hopf C*-algebra and construct the counit and antipode. A Hopf C*-algebra is a C*-algebra with comultiplication satisfying some extra condition which makes possible the construction of the counit and antipode. The leading example is of course the C*-algebra of continuous, vanishing at infinity functions on a locally

Helmut Prodinger

We prove a q-analogue of the formula $ \sum_{1\le k\le n} \binom nk(-1)^{k-1}\sum_{1\le i_1\le i_2\le... \le i_m=k}\frac1{i_1i_2... i_m} = \sum_{1\le k\le n}\frac{1}{k^m} $ by inverting a formula due to Dilcher.

L. Bayle, A. Beauville

We give a "modern" version, based on Mori theory, of the classification of birational involutions of P^2 up to conjugacy. The result has been known for more than one century but the classical proofs are not always convincing.

A. Yu. Savin, B. Yu. Sternin

In the paper we consider the theory of elliptic operators acting in subspaces defined by pseudodifferential projections. This theory on closed manifolds is connected with the theory of boundary value problems for operators violating Atiyah-Bott condition. We prove an index formula for elliptic operators in subspaces defined by even projections on odd-dimensi

Ichiro Oda

Starting with Green-Schwarz superstring action, we construct a type IIB matrix model. We fix the local $κ$ symmetry in the Killing spinor gauge and then perform the world-sheet duality transformation. A matrix model obtained from this gauge-fixed action is shown to be equivalent to the type IIB matrix model constructed by Ishibashi et al. Our construction do

Ram Brustein, Stefano Foffa, Riccardo Sturani

A generalized second law in string cosmology accounts for geometric and quantum entropy in addition to ordinary sources of entropy. The proposed generalized second law forbids singular string cosmologies, under certain conditions, and forces a graceful exit transition from dilaton-driven inflation by bounding curvature and dilaton kinetic energy.

Thordur Jonsson, George K. Savvidy

We study the spectral properties of the transfer matrix for a gonihedric random surface model on a three-dimensional lattice. The transfer matrix is indexed by generalized loops in a natural fashion and is invariant under a group of motions in loop-space. The eigenvalues of the transfer matrix can be evaluated exactly in terms of the partition function, the

B. A. Lysov, O. F. Dorofeyev

Solutions, exactly expressed in terms of elementary functions (unique Laughlin states), of the correlated motion problem for a pair of 2D-electrons in a constant and uniform magnetic field have been shown to exist for a certain relation between the magnetic field induction and the electron charge. Arguments that can help to understand the physical meaning of

Wataru Souma

The non-trivial ultraviolet fixed point in quantum gravity is calculated by means of the exact renormalization group equation in d-dimensions $(2\simeq d\leq4)$. It is shown that the ultraviolet non-Gaussian fixed point which is expected from the perturbatively $ε$-expanded calculations in $2+ε$ gravity theory remains in d=4. Hence it is possible that quantu

J. A. Harvey, G. Moore

We investigate nonperturbative effects in M-theory compactifications arising from wrapped membranes. In particular, we show that in $d=4, \mathcal{N}=1$ compactifications along manifolds of $G_2$ holonomy, membranes wrapped on rigid supersymmetric 3-cycles induce nonzero corrections to the superpotential. Thus, membrane instantons destabilize many M-theory c

Rafal Moderski, Marek Rogatko

It has been argued that the extremal dilaton black holes exhibit a flux expulsion of Abelian-Higgs vortices. We re-examine carefully the problem and give analytic proofs for the flux expulsion always takes place. We also conduct numerical analysis of the problem using three initial data sets on the horizon of an extreme dilatonic black hole, namely, core, va

Y. S. Myung, H. W. Lee, Jin Young Kim

In the type 0B string theory, we discuss the role of tachyon($T$) and fixed scalars($ν,λ$). The issue is to explain the difference between tachyon and fixed scalars in the D$5_{\pm}$-D$1_{\pm}$ black hole background. For this purpose, we perform the semiclassical calculation. Here one finds a mixing between ($ν, λ, T$) and the other fields. Using the decoupl

Sergey A. Cherkis

Supergravity solution describing two intersecting M5-branes is presented. The branes are fixed in the relative transverse directions and are delocalized along the overall transverse ones. The intersection can be smoothed, so that the M5-branes present one holomorphic cycle. We also obtain a solution corresponding to an M5-brane on a holomorphic cycle of mult

T. Barnes

In this contribution I review recent experimental developments in the spectroscopy of higher-mass mesons, especially candidate radial excitations discussed at the WHS99 meeting in Frascati.

R. C. Brower, J. McGreevy, C-I Tan

Using generic properties of string theories, we show how interesting non-perturbative features of QCD can be exploited in heavy ion collisions. In particular, a generalized "semi-circle" law for the phase diagram in the temperature-chemical potential plane is derived.

S. I. Bityukov, N. V. Krasnikov

We investigate squark and gluino pair production at LHC (CMS) with subsequent decays into quarks and LSP for the case of nonuniversal gaugino masses. Visibility of signal by an excess over SM background in (n > 1)jets + E^{miss}_T events depends rather strongly on the relation between LSP, gluino and squark masses and it decreases with the increase of LSP ma

A. Nikitenko, A. Starodumov, N. Stepanov

We have updated our previous study on the possibility to observe the rare B0_s -> 2mu decay with detailed simulation of the TDR version of the CMS detector. The full simulation and reconstruction procedure has been done both for the signal and background. We improved our previous results on expected sensitivity using more sophisticated algorithms for the tra

V. B. Semikoz, A. A. Bykov, V. Yu. Popov, A. I. Rez

The magnetic field in the solar convective zone has a random small-scale component with the r.m.s. value substancially exceeding the strength of a regular large-scale field. For two Majorana neutrino flavors and two helicities in the presence of a neutrino transition magnetic moment and nonzero neutrino mixing we analize the displacement of the allowed (Delt

I. Schienbein

Parameter-free and perturbatively stable leading order (LO) and next-to-leading order (NLO) parton densities for real and virtual photons are presented.

B. B. Levchenko

A new Lorentz frame for DIS jet finding is suggested.

H. Anlauf, A. B. Arbuzov, E. A. Kuraev

We report on the calculation of the QED radiative corrections to deep inelastic scattering with a tagged photon with next-to-leading logarithmic accuracy. Numerical results are given for different experimental setups for the case of the HERA collider.

Peter Petreczky

This thesis is devoted to the study of the screening masses in hot non-Abelian theories. Section 1 contain a brief introduction to the topic. In section 2 a detailed overview of the screening phenomena and their applications is given. In section 3 the screening masses are defined through the coupled gap equations. Section 4 deals with the determination of th

Melissa Lampert, Benjamin Svetitsky

We have studied plasma oscillations in a flux tube created in a dual superconductor. Starting from a static flux tube configuration, with electric charges at either end, we release a fluid of electric charges in the system that accelerate and screen the electric field. The weakening of the electric field allows the flux tube to collapse, and the inertia of t

Christer Friberg, Torbjörn Sjöstrand

The production of jets is studied in collisions of virtual photons, gamma*-p and gamma*-gamma*, specifically for applications at HERA and LEP2. Photon flux factors are convoluted with matrix elements involving either direct or resolved photons and, for the latter, with parton distributions of the photon. Special emphasis is put on the range of uncertainty in

Kiwoon Choi, Jai-chan Hwang, Kyu Wan Hwang

We examine the effects of the axion coupling to $R\tilde{R}$ on the evolution of cosmic structures. It is shown that the evolutions of the scalar- and vector-type perturbations are not affected by this axion coupling. However the axion coupling causes an asymmetric evolution of the two polarization states of the tensor-type perturbation, which may lead to a

Dario Sassi Thober

The Dirac monopole is discussed in view of the gauge invariance in Quantum Electrodynamics. It is shown the monopole existence implies the violation of the gauge invariance principle. The monopole field is essentially a longitudinal field and so a mass is naturally associated to it. Interpretation for the case the monopole charge is different from zero is ad

Michael S. Chanowitz

The measured value of A_b, the Z \bar bb asymmetry parameter, disagrees with the Standard Model at 99% confidence level. If genuine the discrepancy could indicate new interactions unique to third generation quarks, implying enhanced Z penguin amplitudes. Enhanced rates are predicted for rare K and B decays, such as K^{+} --> pi^{+}\bar nu nu, K_{L} --> pi^{0

Stefano Forte

We review several recent developments in the theory and phenomenology of deep-inelastic scattering, with particular emphasis on precision tests of QCD and progress in the detailed perturbative treatment of structure functions and parton distributions. We discuss specifically determinations of alpha_s; higher twist contributions to structure functions and ren

Artan Borici

Lattice regularization of chiral fermions is an important development of the theory of elementary particles. Nontheless, brute force computer simulations are very expensive, if not prohibitive. In this letter I exploit the non-interacting character of the lattice theory in the flavor space and propose a multigrid approach for the simulation of the theory. Al

CMD2 Collaboration

Using the $1.9 pb^{-1}$ of data collected with the CMD-2 detector at VEPP-2M the decay mode $ϕ\to ηγ$, $η\to π^+π^-π^0$ has been studied. The obtained branching ratio is B($ϕ\to ηγ) = (1.18 \pm 0.03 \pm 0.06) %$.

Piotr Jaranowski, Gerhard Schäfer

The Brill-Lindquist time-symmetric initial-value solution for two uncharged black holes is rederived using the Hamiltonian constraint equation with Dirac delta distributions as a source for the binary black-hole field. The bare masses of the Brill-Lindquist black holes are introduced in a way which is applied, after straightforward modification, to the Misne

Yakov Itin, Shmuel Kaniel

Let a differential 4D-manifold with a smooth coframe field be given. Consider the operators on it that are linear in the second order derivatives or quadratic in the first order derivatives of the coframe, both with coefficients that depend on the coframe variables. The paper exhibits the class of operators that are invariant under a general change of coordi

J. Podolsky, J. B. Griffiths

We explicitly demonstrate that the known solutions for expanding impulsive spherical gravitational waves that have been obtained by a "cut and paste" method may be considered to be impulsive limits of the Robinson-Trautman vacuum type N solutions. We extend these results to all the generically distinct subclasses of these solutions in Minkowski, de S

C. Kohler

A class of theories of gravitation that naturally incorporates preferred frames of reference is presented. The underlying space-time geometry consists of a partial parallelization of space-time and has properties of Riemann-Cartan as well as teleparallel geometry. Within this geometry, the kinematic quantities of preferred frames are associated with torsion

Chad Clark, William A. Hiscock, Shane L. Larson

The null geodesic equations in the Alcubierre warp drive spacetime are numerically integrated to determine the angular deflection and redshift of photons which propagate through the distortion of the ``warp drive'' bubble to reach an observer at the origin of the warp effect. We find that for a starship with an effective warp speed exceeding the spee

Alexander S. Szalay, Peter Kunszt, Ani Thakar, Jim Gray

The next-generation astronomy digital archives will cover most of the universe at fine resolution in many wave-lengths, from X-rays to ultraviolet, optical, and infrared. The archives will be stored at diverse geographical locations. One of the first of these projects, the Sloan Digital Sky Survey (SDSS) will create a 5-wavelength catalog over 10,000 square

Janine Toole, Fred Popowich, Devlan Nicholson, Davide Turcato

In this paper we present an application of explanation-based learning (EBL) in the parsing module of a real-time English-Spanish machine translation system designed to translate closed captions. We discuss the efficiency/coverage trade-offs available in EBL and introduce the techniques we use to increase coverage while maintaining a high level of space and t

Erik F. Tjong Kim Sang, Jorn Veenstra

Dividing sentences in chunks of words is a useful preprocessing step for parsing, information extraction and information retrieval. (Ramshaw and Marcus, 1995) have introduced a "convenient" data representation for chunking by converting it to a tagging task. In this paper we will examine seven different data representations for the problem of recogni

L. O. Manuel, H. A. Ceccatto

We study the stability of homogeneous magnetic phases in a generalized t-J model including a same-sublattice hopping t' and nearest-neighbor repulsion V by means of the slave fermion-Schwinger boson representation of spin operators. At mean-field order we find, in agreement with other authors, that the inclusion of further-neighbor hopping and Coulomb re

R. Wortis, A. J. Berlinsky, C. Kallin

We present calculations of the rate of planar Cu spin lattice relaxation in the mixed state of YBaCuO due to (i) vortex vibrations and (ii) electron spin-flip scattering. We emphasize that both mechanisms give position dependent rates due to the presence of vortices, and hence the magnetization recovery is characterized by a distribution of rates. We conclud

Eldon G. Emberly, George Kirczenow

Using the Landauer formulation of transport theory and tight binding models of the electronic structure, we study electron transport through atomic wires that form 1D constrictions between pairs of metallic nano-contacts. Our results are interpreted in terms of electron standing waves formed in the atomic wires due to interference of electron waves reflected

Vincent Berseth

Thanks to the 9 contacts deposited on the surface of a high quality YBCO twinned single crystal, we investigate both vortex guided motion along twins and the mixed state Hall effect. Firstly, we clearly identify the vortex phase transition and show that, when the magnetic field is along the twin boundaries (within about 2 degrees), the vortex solid is a Bose

A. E. Allahverdyan, Th. M. Nieuwenhuizen, D. B. Saakian

In a $p$-spin interaction spherical spin-glass model both the spins and the couplings are allowed to change in the course of time. The spins are coupled to a heat bath with temperature $T$, while the coupling constants are coupled to a bath having temperature $T_{J}$. In an adiabatic limit (where relaxation time of the couplings is much larger that of the sp

A. K. Rajagopal, Mogus Mochena

The group theory framework developed by Fukutome for a systematic analysis of the various broken symmetry types of Hartree-Fock solutions exhibiting spin structures is here extended to the general many body context using spinor-Green function formalism for describing magnetic systems. Consequences of this theory are discussed for examining the magnetism of i

V. N. Smolyaninova, C. R. Galley, R. L. Greene

We report an experimental study of the time dependence of the resistivity and magnetization of charge-ordered La$_{0.5}$Ca$_{0.5}$MnO$_{3}$ under different thermal and magnetic field conditions. A relaxation with a stretched exponential time dependence has been observed at temperatures below the charge ordering temperature. A model using a hierarchical distr

Yuli V. Nazarov, B. Mijling

We study the linear Hall response of 2D ballistic system on inhomogeneous magnetic field. We establish that in classical limit the Hall conductivity response on local magnetic field is quantized in units of $α_H \equiv \frac{e^3}{2 π^2 \hbar c}$. The quantized value depends on the point where the field is applied, this dependence being irregular in chaotic b

E. Hankiewicz, R. Buczko, Z. Wilamowski

The possibility of formation of a new type of polaron based on the quantum aniferromagnet (AF) model is reported. We take into account exchange interactions between localized d-d spins of the AF, as well as the p-d interaction of the AF with p-carriers. The energy minimum is found when maximum charge density occurs on every second spin. The formation of such

H. Scherer, Th. Weimann, P. Hinze, B. W. Samwer

We report about the fabrication and analysis of the properties of Cr/CrO_x/Cr tunnel junctions and SET transistors, prepared by different variants of direct-writing multilayer technique. In all cases, the CrO_x tunnel barriers were formed in air under ambient conditions. From the experiments on single junctions, values for the effective barrier height and th

J. - Q. Liang, L. Maharana, H. J. W. Mueller-Kirsten

The significance of the Wess--Zumino term in spin tunneling is explored, and a formula is established for the splitting of energy levels of a particle with large fermionic spin as an applied magnetic field is switched on.

Yusuke Tomita, Yutaka Okabe, Chin-Kun Hu

Based on the connection between the Ising model and a correlated percolation model, we calculate the distribution function for the fraction ($c$) of lattice sites in percolating clusters in subgraphs with $n$ percolating clusters, $f_n(c)$, and the distribution function for magnetization ($m$) in subgraphs with $n$ percolating clusters, $p_n(m)$. We find tha

Alessandro Magni, Gabor Vertesy

The dipolar-random field Ising model (DRFIM) recently introduced displays a behaviour that can be connected to the magnetization of bidimensional magnetic media. Epitaxial magnetic garnet films seem to be the ideal test material for such a model. In this work the results of the measurements performed on garnet samples are presented, as well as the comparison

Alessandro Magni

We present a modified two-dimensional random field Ising model, where a dipolar interaction term is added to the classic random field Hamiltonian. In a similar model it was already verified that the system state can exhibit domains in the form of stripe patterns, typical of thin materials with strong perpendicular anisotropy. In this work we show that the hy

Sergey E. Savelev, G. Ramirez-Santiago

By mapping the hamiltonian of the spin one ferromagnet onto that of the classical spherical model we investigate the possible phase transitions and the phase diagram of the spin one ferromagnet. Similarly to what happens in the spherical model we find no phase transition in one and two dimensions. Nonetheless, for three dimensions we obtain a phase diagram i

B. K. Chakraverty

If phase coherence determines the superconducting transition temperature Tc in the cuprate oxides, it is of great interest to understand the role that dynamics of the phase fluctuation plays in bringing about depletion of the superconducting condensate. We will show that a phase correlation function can be calculated that allows us to describe depletion of s

J. Arnhold, P. Grassberger, K. Lehnertz, C. E. Elger

We present a measure for characterizing statistical relationships between two time sequences. In contrast to commonly used measures like cross-correlations, coherence and mutual information, the proposed measure is non-symmetric and provides information about the direction of interdependence. It is closely related to recent attempts to detect generalized syn

Dimitri Bourilkov

The Monte Carlo program ARROW, based on GEANT and using GHEISHA at energies below 30 GeV, is developed for simulation of the hadron and muon components of extensive air showers with primary energy $10^{12}-10^{17}$ eV. Calculations of the characteristics of multi-muon events as observed underground by the LEP detectors are presented and their dependence on t

J. Isern, E. Garcia-Berro, M. Hernanz, G. Chabrier

The evolution of white dwarfs is a cooling process that depends on the energy stored in the core and on the way in which it is transferred through the envelope. In this paper we show that despite some (erroneous) claims, the redistribution of chemical elements ensuing the crystallization of C/O white dwarfs provides between the 10% and the 20% of the total e

Richard P. Nelson, John C. B. Papaloizou

We present the results of a study of propagating warp or bending waves in accretion discs. Three dimensional hydrodynamic simulations were performed using SPH, and the results of these are compared with calculations based on the linear theory of warped discs. We consider primarily the physical regime in which the dimensionless viscosity parameter `alpha'

Steven Brandt, Peter Anninos

We present results from numerical evolutions of single black holes distorted by axisymmetric, but equatorially asymmetric, gravitational (Brill) waves. Net radiated energies, apparent horizon embeddings, and recoil velocities are shown for a range of Brill wave parameters, including both even and odd parity distortions of Schwarzschild black holes. We find t

T. P. Krichbaum, A. Witzel, J. A. Zensus

We discuss the advantages which the next generation interferometer SKA (the Square Kilometer Array) will bring for Very Long Baseline Interferometry (VLBI) at centimeter wavelengths. With a sensitivity to micro-Jy level flux density, a brightness temperature limit of about 10.000 K, and an expected dynamic range in future VLBI maps of better than 1.000.000,

R. Buonanno, C. E. Corsi, M. Castellani, G. Marconi

Using observations from the Hubble Space Telescope archive, color-magnitude diagrams (CMDs) have been constructed for globular cluster 4 in the Fornax dSph galaxy and its surrounding field. These diagrams extend below the main-sequence turnoffs and have yielded measurements of the ages of the populations. The most prominent features of the CMD of the Fornax

A. I. Terlevich, H. Kuntschner, R. G. Bower, N. Caldwell

We use the $C_{2}4668$, $Fe4383$, $Hγ_A$ and $Hδ_A$ spectral absorption line indices, together with U- and V-band photometry of 101 galaxies in the Coma cluster, to investigate how mean age and metal abundance correlate with galaxy luminosity. In particular, we use the line index measurements to address the origin of the colour-magnitude relation (CMR). We f

K. -L. Kratz, B. Pfeiffer, F. -K. Thielemann, W. B. Walters

The focus of the present review is the production of the heaviest elements in nature via the r-process. A correct understanding and modeling requires the knowledge of nuclear properties far from stability and a detailed prescription of the astrophysical environment. Experiments at CERN/ISOLDE have played a pioneering role in exploring the characteristics of

Davide Lazzati, Gabriele Ghisellini

We investigate, independently of specific emission models, the constraints on the value of the bulk Lorentz factor Gamma of a fireball. We assume that the burst emission comes from internal shocks in a region transparent to Thomson scattering and before deceleration due to the swept up external matter is effective. We consider the role of Compton drag in dec

T. Venturi, S. Bardelli, G. Zambelli, R. Morganti

In this paper we present the first results of a radio survey at 22 cm in the central region of the Shapley Concentration, carried out with the Australia Telescope Compact Array. In order to study the effect of merging on the statistical properties of radio galaxies, and the relation between merging and the existence of {\it relic} and {\it halo} type radio s

M. Guainazzi, A. N. Parmar, T. Oosterbroek

During a BeppoSAX observation of the X-ray burst source X1732-304 located in the globular cluster Terzan 1 in 1999 April, the source was detected in an anomalously low-state with an X-ray luminosity of 1.4 x 10^33 erg/s$, about 300 times fainter than the lowest previously reported measure of the persistent flux. The spectral shape and intensity of this low-s

A. P. Jones

We review the use of elemental depletions in determining the composition of interstellar dust and present a new interpretation of the elemental depletion patterns for the dust forming elements in a range of diffuse cloud types. We discuss this within the context of dust processing in the ISM and show that Si and Mg are selectively eroded from dust, with resp

Pierluigi Monaco, Giuseppe Murante

The cosmological mass function problem is analyzed in full detail in the case of 1D gravity, with analytical, semi-analytical and numerical techniques. The extended Press & Schechter theory is improved by detailing the relation between smoothing radius and mass of the objects. This is done by introducing in the formalism the concept of a growth curve for the

Marco Chiaberge, Alessandro Capetti, Annalisa Celotti

Unresolved nuclear sources are detected by the Hubble Space Telescope in the great majority of a complete sample of 33 FR I radio galaxies belonging to the 3CR catalogue. The optical flux of these Central Compact Cores (CCC) shows a striking linear correlation with the radio core one over four decades, arguing for a non--thermal synchrotron origin of the CCC

J. Hwang, H. Noh

Relativistic cosmological perturbation analyses can be made based on several different fundamental gauge conditions. In the pressureless limit the variables in certain gauge conditions show the correct Newtonian behaviors. Considering the general curvature ($K$) and the cosmological constant ($Λ$) in the background medium, the perturbed density in the comovi

Robert I McLachlan

Incompressible two-dimensional flows such as the advection (Liouville) equation and the Euler equations have a large family of conservation laws related to conservation of area. We present two Eulerian numerical methods which preserve a discrete analog of area. The first is a fully discrete model based on a rearrangement of cells; the second is more conventi

Robert McLachlan, Nicolas Robidoux

`Dual composition', a new method of constructing energy-preserving discretizations of conservative PDEs, is introduced. It extends the summation-by-parts approach to arbitrary differential operators and conserved quantities. Links to pseudospectral, Galerkin, antialiasing, and Hamiltonian methods are discussed.

Eric G. Blackman

A generalized mean magnetic field induction equation for differential rotators is derived, including a compressibility, and the anisotropy induced on the turbulent quantities from the mean magnetic field itself and a mean velocity shear. Derivations of the mean field equations often do not emphasize that there must be anisotropy and inhomogeneity in the turb

L. M. Diaz-Rivera, L. O. Pimentel

In the context of a family os scalar-tensor theories with a dynamical $Λ$, that is a binomial on the scalar field, the cosmological equations are considered. A general barotropic state equation $p=(γ-1)ρ$, for a perfect fluid is used for the matter content of the Universe. Some Friedmann- Robertson-Walker exact solutions are found, they have scale factor wic

The E864 Collaboration

Light nuclei can be produced in the central reaction zone via coalescence in relativistic heavy ion collisions. E864 at BNL has measured the production of ten light nuclei with nuclear number of A=1 to A=7 at rapidity $y\simeq1.9$ and $p_{T}/A\leq300MeV/c$. Data were taken with a Au beam of momentum of 11.5 A $GeV/c$ on a Pb or Pt target with different exper

W. James Stirling, Anja Werthenbach

The production of $ν\barν γγ$ in high-energy $e^+e^-$ collisions offers a window on anomalous quartic gauge boson couplings. We investigate the effect of two possible anomalous couplings on the cross section for $ν\barν γγ$ production via $WW$-fusion at LEP2 ($\sqrt{s} = 200$ GeV).