January 2003 arXiv papers — page 19

Kaige Wang

We study a general theory on the interference of two-photon wavepacket in a beam splitter (BS). We find that the perfect coalescence interference requires a symmetric spectrum of two-photon wavepacket which can be entangled or un-entangled. Furthermore, we introduce a two-photon wavepacket with anti-symmetric spectrum, which is related with photon entangleme

Hugo J. Woerdeman

In this paper we propose a sequence of tests which gives a definitive test for checking $2\times M$ separability. The test is definitive in the sense that each test corresponds to checking membership in a cone, and that the closure of the union of all these cones consists exactly of {\it all} $2 \times M$ separable states. Membership in each single cone may

Nicolas Garnier, Christiane Normand

The stability of a thermocapillary flow in an extended cylindrical geometry is analyzed. This flow occurs in a thin liquid layer with a disk shape when a radial temperature gradient is applied along the horizontal free surface. Besides the aspect ratio, a second parameter related to the local curvature is introduced to describe completely the geometrical eff

V. Rossetto, A. C. Maggs

Motivated by recent experiments on DNA torsion-force-extension characteristics we consider the writhing geometry of open stiff molecules. We exhibit a cyclic motion which allows arbitrarily large twisting of the end of a molecule via an activated process. This process is suppressed for forces larger than femto-Newtons which allows us to show that experiments

Xiao-Yan Gu, Zhong-Qi Ma, Bin Duan

A new approach is developed to derive the complete spectrum of exact interdimensional degeneracies for a quantum three-body system in D-dimensions. The new method gives a generalization of previous methods.

Slava G. Turyshev

We developed analytical technique for extracting the phase, visibility and amplitude information as needed for interferometric astrometry with the Space Interferometry Mission (SIM). Our model accounts for a number of physical and instrumental effects, and is valid for a general case of bandpass filter. We were able to obtain general solution for polychromat

Mei Xiaochun

It is proved in the paper that the non-conservative dissipative force and asymmetry of time reversal can be naturally introduced into classical statistical mechanics after retarded electromagnetic interaction between charged microparticles is considered. In this way, the rational dynamic foundation for classical statistical physics can established and the re

Takumi Muto, Masatomi Yasuhira, Toshitaka Tatsumi, Naoki Iwamoto

The neutrino mean free paths in hot neutron-star matter are obtained in the presence of kaon condensates. The kaon-induced neutrino absorption process, which is allowed only in the presence of kaon condensates, is considered for both nondegenerate and degenerate neutrinos. The neutrino mean free path due to this process is compared with that for the neutrino

K. Sh Egiyan

The ratios of inclusive electron scattering cross sections of $^4$He, $^{12}$C, and $^{56}$Fe to $^3$He have been measured for the first time. It is shown that these ratios are independent of $x_B$ at Q$^2>$1.4 (GeV/c)$^2$ for $x_B>$ 1.5 where the inclusive cross section depends primarily on the high-momentum components of the nuclear wave function. The obse

Victor J. Sanchez-Morcillo

A dynamical system of equations describing parametric sound generation (PSG) in a dispersive large aspect ratio resonator is derived. The model generalizes previously proposed descriptions of PSG by including diffraction effects, and is analogous to the model used in theoretical studies of optical parametric oscillation. A linear stability analysis of the so

V. P. Berezovoj, Y. L. Bolotin, V. A. Cherkaskiy

We investigate the QMCS in structure of the eigenfunctions, corresponding to mixed type classical dynamics in smooth potential of the surface quadrupole oscillations of a charged liquid drop. Regions of different regimes of classical motion are strictly separated in the configuration space, allowing direct observation of the correlations between the wave fun

Denis Grishin, Thomas Strohmer

An important problem in applications is the approximation of a function $f$ from a finite set of randomly scattered data $f(x_j)$. A common and powerful approach is to construct a trigonometric least squares approximation based on the set of exponentials $\{e^{2πi kx}\}$. This leads to fast numerical algorithms, but suffers from disturbing boundary effects d

Apoloniusz Tyszka

Let G: C^n \times C^n -> C, G((x_1,...,x_n),(y_1,...,y_n))=(x_1-y_1)^2+...+ (x_n-y_n)^2. We say that f: R^n -> C^n preserves distance d>0 if for each x,y \in R^n G(x,y)=d^2 implies G(f(x),f(y))=d^2. Let A(n) denote the set of all positive numbers d such that any map f: R^n -> C^n that preserves unit distance preserves also distance d. Let D(n) denote the set

Michael Larsen

This paper describes a non-deterministic polynomial-time algorithm to find a path of length O(log p loglog p) between any two vertices of the Cayley graph of SL(2,Z/pZ).

Peter A. Becker

Integro-partial differential equations occur in many contexts in mathematical physics. Typical examples include time-dependent diffusion equations containing a parameter (e.g., the temperature) that depends on integrals of the unknown distribution function. The standard approach to solving the resulting nonlinear partial differential equation involves the us

Remi Carles, David Lannes

We consider the asymptotic behavior of solutions to nonlinear partial differential equations in the limit of short wavelength. For initial data which cause focusing at one point, we highlight critical indexes as far as the influence of the nonlinearity in the neighborhood of the caustic is concerned. Our results generalize some previous ones proved by the fi

James Belk, Kai-Uwe Bux

We prove that Richard Thompson's group F is not minimally almost convex with respect to the two standard generators. This improves upon a recent result of S. Cleary and J. Taback. We make use of the forest diagrams for elements of F introduced by J. Belk and K. Brown. These diagrams seem particularly well-suited for understanding the Cayley graph for the

Christian Okonek, Andrei Teleman

This article is an expanded version of talks given by the authors in Oberwolfach, Bochum, and at the Fano Conference in Torino. Some new results (e. g. the material concerning flag varieties, Quot spaces over $¶^1$, and the generalized quiver representations) were included. The main goal is the construction of gauge theoretical Gromov-Witten type invariants

J. Maurice Rojas

Let HN denote the problem of determining whether a system of multivariate polynomials with integer coefficients has a complex root. It has long been known that HN in P implies P=NP and, thanks to recent work of Koiran, it is now known that the truth of the Generalized Riemann Hypothesis (GRH) yields the implication that HN not in NP implies P is not equal to

Stephen Semmes

This paper briefly discusses some questions with analytical and topological aspects, with hopefully some useful references on both sides.

Simon A. King

It is known that any two triangulations of a compact 3-manifold are related by finite sequences of certain local transformations. We prove here an upper bound for the length of a shortest transformation sequence relating any two triangulations of the 3-dimensional projective space, in terms of the number of tetrahedra.

A. L. Cavalcanti de Oliveira, E. R. Bezerra de Mello

We analyze the nonrelativistic quantum scattering problem of a charged particle by an Abelian magnetic monopole in the background of a global monopole. In addition to the magnetic and geometric effects, we consider the influence of the electrostatic self-interaction on the charged particle. Moreover, for the specific case where the electrostatic self-interac

Domenec Espriu, Luca Tagliacozzo

Simulations in compact U(1) lattice gauge theory in 4D show now beyond any reasonable doubts that the phase transition separating the Coulomb from the confined phase is of first order, albeit a very weak one. This settles the issue from the numerical side. On the analytical side, it was suggested some time ago, based on the qualitative analogy between the ph

Nguyen Tien Binh

Returning to the old problems in ordinary QED, by an appropriate extension of the dimensional regularization method in noncommutative space we try to provide a quite coherent look into NCQED.The renormalisation of theories, the $β$ function,the vacuum polarisation of photon, the general structure of vertex fermion-photon, the anomalous magnetic moment (AMM)

Bert Schroer

After a short presentation of KMS states and modular theory as the unifying description of thermalizing systems we propose the absence of transverse vacuum fluctuations in the holographic projections as the mechanism for an area behavior (the transverse area) of localization entropy as opposed to the volume dependence of ordinary heat bath entropy. Thermaliz

E. T. Akhmedov

It is shown that the Holographic Renormalization Group can be formulated universally within Quantum Field Theory as (the quantization of) the Hamiltonian flow on the cotangent bundle to the space of gauge-invariant single-trace operators supplied with the canonical symplectic structure. The classical Hamiltonian dynamics is recovered in the large $N$ limit.

P. Kielanowski, S. R. Juarez W

We present here the most important ideas, equations and solutions for the running of all the quark Yukawa couplings and all the elements of the Cabibbo-Kobayashi-Maskawa matrix, in the approximation of one loop, and up to order $λ^{4}$, where $λ\sim 0.22$ is the sine of the Cabibbo angle. Our purpose is to determine what the evolution of these parameters may

Daniele Binosi, Joannis Papavassiliou

The all-order construction of the pinch technique gluon self-energy and quark-gluon vertex is presented in detail within the class of linear covariant gauges. The main ingredients in our analysis are the identification of a special Green's function, which serves as a common kernel to all self-energy and vertex diagrams, and the judicious use of the Slavn

A. Arrizabalaga, J. Smit

We discuss the method of $Φ$-derivable approximations in gauge theories. There, two complications arise, namely the violation of Bose symmetry in correlation functions and the gauge dependence. For the latter we argue that the error introduced by the gauge dependent terms is controlled, therefore not invalidating the method.

Rahul Basu, K. Sridhar

Dilepton production in heavy ion collisions, in the Intermediate Mass Region (IMR) has consistently shown an excess over theoretical estimates. An attempt to understand this discrepancy between the observed dilepton pairs and the theoretical estimate is made here through the production of the $η_c$ meson and estimates obtained by NRQCD calculations. We find

Yong Zhou

In order to obtain proper wave-function renormalization constants for unstable fermion and consist with Breit-Wigner formula in the resonant region, We have assumed an extension of the LSZ reduction formula for unstable fermion and adopted on-shell mass renormalization scheme in the framework of without field renormaization. The comparison of gauge dependenc

John P. Ralston

Recently Buniy and Kephart made an astonishing empirical observation, which anyone can reproduce at home. Measure the {\it lengths} of closed knots tied from ordinary rope. The ``double do-nut'', and the beautiful trefoil knot are examples. Tie the knots tightly, and glue or splice the tails into a seamless unity. Compare two knots with corresponding

P. Faccioli

We present a study of the QCD interactions which do not conserve the chirality of quarks. These non-perturbative forces are responsible for the violation of the U_A(1) charge conservation and for the breaking of chiral symmetry. From a systematic analysis we argue that the leading dynamical sources chirality flips are the interactions mediated by topological

I. Montvay

The computational cost of numerical simulations of QCD with light dynamical Wilson-quarks is estimated by determining the autocorrelation of various quantities. In test runs the expected qualitative behaviour of the pion mass and coupling at small quark masses is observed.

Murray Moinester

The electric alpha and magnetic beta pion Compton polarizabilities characterize the pion's deformation in the electromagnetic field of the gamma during gamma-pi Compton scattering. The pion polarizabilities are key observables, and provide stringent tests of our understanding of chiral symmetry, its spontaneous breakdown, the role of explicit symmetry br

Laura Salmi

A top-quark reconstruction method for CLIC is described. The reconstructed events are used to measure the e+ e- -> t \bar{t} cross-section as well as the forward-backward asymmetry. The results suggest that the relative measurement accuracy for the cross-section will be 1.4 % and for the asymmetry 4.2 % for 1 ab^{-1} of data.

V. Dzhunushaliev

The flux tube solutions in 5D Kaluza-Klein theory can be considered as a string-like object - $Δ-$string. The initial 5D metric can be reduced to some inner degrees of freedom living on the $Δ-$string. The propagation of electromagnetic waves through the $Δ-$string is considered. It is shown that the difference between $Δ$ and ordinary strings are connected

Michael J. O'Donnell

An Open Network Handle System (ONHS) provides an intermediate level of service between IP numbers and domain names. A handle adheres permanently to an owner, who may assign and reassign it to different addresses at will. But a handle is a number, carrying no significance in natural language. Any user desiring a handle may generate one from a public key. This

J. W. Landry, S. N. Coppersmith

We have computed the low energy quantum states and low frequency dynamical susceptibility of complex quantum spin systems in the limit of strong interactions, obtaining exact results for system sizes enormously larger than accessible previously. The ground state is a complex superposition of a substantial fraction of all the classical ground states, and yet

Rui-Hua Xie, Qin Rao

Two-mode quantized electromagnetic fields can be entangled and admit a large number of coherent states. In this paper, we consider a two-mode system that consists of a two-level atom interacting with a two-mode quantized electromagnetic field, which is initially prepared in an entangled two-mode coherent state, via a nondegenerate two-photon process in a los

Rui-Hua Xie, Qin Rao

In our preceding serial works, we have investigated the generation of higher-order atomic dipole squeezing (HOADS) in a high-Q micromaser cavity, discussing the effects of dynamic Stark shift, atomic damping, atomic coherence and nonlinear one-photon processes and different initial states (for example, correlated and uncorrelated states, superposition states

Daniel Eriksson, Henrik Jeldtoft Jensen

We study selection acting on phenotype in a collection of agents playing local games lacking Nash equilibria. After each cycle one of the agents losing most games is replaced by a new agent with new random strategy and game partner. The network generated can be considered critical in the sense that the lifetimes of the agents is power law distributed. The lo

M. B. Salamon, S. H. Chun

The large, so-called colossal, magnetoresistivity of doped manganese oxides based on LaMnO3 has attracted considerable attention, but only one unusual feature of the ferromagnetic transition in these compounds. We examine in this paper the progression of magnetic and thermodynamic behavior as the transition temperature is made to vary from 360 K to 218 K by

Jaroslav Fabian, Joseph L. Feldman, C. Stephen Hellberg, S. M. Nakhmanson

The anharmonic decay rates of atomic vibrations in amorphous silicon (a-Si) and paracrystalline silicon (p-Si), containing small crystalline grains embedded in a disordered matrix, are calculated using realistic structural models. The models are 1000-atom four-coordinated networks relaxed to a local minimum of the Stillinger-Weber interatomic potential. The

A. J. Greer, D. R. Harshman, W. J. Kossler, A. Goonewardene

We report a study of the organic compound $(TMTSF)_2 ClO_4$ in both a sample cooled very slowly through the anion ordering temperature (relaxed state) and a sample cooled more rapidly (intermediate state). For the relaxed state the entire sample is observed to be superconducting below about T_c ~ 1.2 K. The second moment of the internal field distribution wa

E. Ben-Naim, P. L. Krapivsky

Dynamics of inelastic gases are studied within the framework of random collision processes. The corresponding Boltzmann equation with uniform collision rates is solved analytically for gases, impurities, and mixtures. Generally, the energy dissipation leads to a significant departure from the elastic case. Specifically, the velocity distributions have overpo

C. J. Olson Reichhardt, C. Reichhardt, I. Martin, A. R. Bishop

Two-dimensional systems in which there is a competition between long-range repulsion and short range attraction exhibit a remarkable variety of patterns such as stripes, bubbles, and labyrinths. Such systems include magnetic films, Langmuir monolayers, polymers, gels, water-oil mixtures, and two-dimensional electron systems. In many of these systems quenched

Z. Sefrioui, D Arias, V. Pena, J. E. Villegas

We study the interplay between magnetism and superconductivity in high quality YBa2Cu3O7 (YBCO) / La0.7Ca0.3MnO3(LCMO)superlattices. We find evidence for the YBCO superconductivity depression in presence of the LCMO layers. We show that due to its short coherence length superconductivity survives in the YBCO down to much smaller thickness in presence of the

J. S. Kim, D. Hall, P. Kumar, G. R. Stewart

The large $Δ$C observed at 17.5 K in URu$_{2}$Si$_{2}$ is inconsistent with the small, 0.04 $μ_{B}$ moment measured for the antiferromagnetism observed starting (perhaps coincidentally) at the same temperature. We report measurements of this specific heat transition, thought to be due to some 'hidden order', in magnetic fields between 24 and 42 T, i.

Yuriy I. Kuzmin

Statistical properties of the critical current distribution in superconductor with fractal clusters of a normal phase are considered. It is found that there is the range of fractal dimensions in which the variance and expectation for this distribution increases infinitely. Simple technique of avoiding such a divergence by the use of truncated distributions i

M. Paulsson, S. Datta

We provide a theoretical estimate of the thermoelectric current and voltage over a Phenyldithiol molecule. We also show that the thermoelectric voltage is (1) easy to analyze, (2) insensitive to the detailed coupling to the contacts, (3) large enough to be measured and (4) give valuable information, which is not readily accessible through other experiments,

S. S. Banerjee, A. Soibel, Y. Myasoedov, M. Rappaport

Bitter decoration and magneto-optical studies reveal that in heavy-ion irradiated superconductors, a 'porous' vortex matter is formed when vortices outnumber columnar defects (CDs). In this state ordered vortex crystallites are embedded in the 'pores' of a rigid matrix of vortices pinned on CDs. The crystallites melt through a first-order transition while th

Jayanth R. Banavar, Amos Maritan

A framework is presented for understanding the common character of proteins. Proteins are linear chain molecules. However, the simple model of a polymer viewed as spheres tethered together does not account for many of the observed characteristics of protein structures. The authors show here that proteins may be regarded as tubes of nonzero thickness. This ap

E. Falck, O. Punkkinen, I. Vattulainen, T. Ala-Nissila

The breakdown of dynamical scaling for a dilute polymer solution in 2D has been suggested by Shannon and Choy [Phys. Rev. Lett. {\bf 79}, 1455 (1997)]. However, we show here both numerically and analytically that dynamical scaling holds when the finite-size dependence of the relevant dynamical quantities is properly taken into account. We carry out large-sca

Z. D. Kvon, Y. Y. Proskuryakov, A. K. Savchenko

We report the observation of an anomalous state of a 2D electron gas near a vicinal surface of a silicon MOSFET in high magnetic fields. It is characterised by unusual behaviour of the conductivities $σ_{xx}$ and $σ_{xy}$, which can be described as a collapse of the Zeeman spin splitting accompanied by a large peak in $σ_{xx}$ and an anomalous peak in $ σ_{x

Jayanth R. Banavar, John Damuth, Amos Maritan, Andrea Rinaldo

Recently, West et al. claimed to derive a general quantitative model based on fundamental principles for the allocation of metabolic energy between maintenance of existing tissue and the production of new biomass, and in addition claimed to derive a single, parameterless universal curve that describes the growth of many species. They further claimed that the

Nigel B. Wilding

We report a Monte Carlo finite-size scaling study of the demixing transition of a symmetrical Lennard-Jones binary fluid mixture. For equal concentration of species, and for a choice of the unlike-to-like interaction ratio delta=0.7, this transition is found to be continuous at liquid-vapor coexistence. The associated critical end point exhibits Ising-like u

L. Petit, A. Svane, W. M. Temmerman, Z. Szotek

The electronic structure of UPd_2Al_3 is described using the self-interaction corrected local-spin-density approximation to density functional theory. The groundstate is found to be characterized by the coexistence of localized (f^2) and delocalized U f electrons, in agreement with experimental evidence. We observe significant difference in electronic struct

A. Nowicka, P. Mackiewicz, M. Dudkiewicz, D. Mackiewicz

We have found that the effective survival time of amino acids in organisms follows a power law with respect to frequency of their occurrence in genes. We have used mutation data matrix PAM1 PET91 to calculate selection pressure on each kind of amino acid. The results have been compared to MPM1 matrix (Mutation Probability Matrix) representing the pure mutati

Yu Zhu, Qing-feng Sun, Tsung-han Lin

We propose an efficient mechanism for the operation of writing spin in a quantum dot, which is an ideal candidate for qubit. The idea is based on the Andreev reflection induced spin polarization (ARISP) in a ferromagnetic / quantum-dot / superconductor system. We find that on the resonance of Andreev reflection, the spin polarization of quantum dot strongly

T. K. Kopec, T. P. Polak

We study a quantum Hamiltonian that models an two--dimensional array of Josephson junctions with short range Josephson couplings, (given by the Josephson energy E_J and charging energiey E_C due to the small capacitance of the junctions. We include the effects from both the self-C0 and the junction-C1 capacitances in the presence of external magnetic flux f=

E. -J. Cho, R. -J. Jung, B. -H. Choi, S. -J. Oh

The bulk-sensitive Ce 4$f$ spectral weights of various Ce compounds including CeFe$_2$, CeNi$_2$, and CeSi$_2$ were obtained with the resonant photoemission technique at the Ce 3d-edge. We found the lineshapes change significantly with the small change of the incident photon energy. Detailed analysis showed that this phenomenon results primarily from the Aug

Diptiman Sen

We use first-order perturbation theory near the fermionic limit of the delta-function Bose gas in one dimension (i.e., a system of weakly interacting fermions) to study three situations of physical interest. The calculation is done using a pseudopotential which takes the form of a two-body delta''-function interaction. The three cases considered are

Ran-Ju Jung, Byung-Hee Choi, Hyeong-Do Kim, S. -J. Oh

We have measured Ce 4f spectral weights of extremely $α$-like Ce-transition metal intermetallic compounds CeRh$_x$ (x=2,3) and CeNi$_x$ (x=2,5) by using the {\it bulk-sensitive} resonant photoemission technique at the Ce $M_5$($3d_{5/2}\to4f$)-edge. Unprecedentedly high energy resolution and longer escape depth of photoemitted electron at this photon energy

Makoto Kuwabara, Hitoshi Seo, Masao Ogata

The electronic properties of quarter-filled organic materials showing spin-Peierls transition are investigated theoretically. By studying the one-dimensional extended Peierls-Hubbard model analytically as well as numerically, we find that there is a competition between two different spin-Peierls states due to the tetramized lattice distortion in the strongly

B. I. Belevtsev, B. D. Hennings, K. D. D. Rathnayaka, D. G. Naugle

We present here an overview of thermal conductivity behavior in magnetic superconductors: rare-earth nickel borocarbide intermetallic compounds, RNi_{2}B_{2}C, and the 2122 rare-earth rutheno-cuprates. The borocarbide family of intermetallics exhibits the large variety of phenomena - only superconductivity (R = Y, Lu), coexistence of superconductivity and ma

D. Bodea, M. Crisan, I. Grosu, I. Tifrea

We propose a model for the non-Fermi behavior in the proximity of the quantum phase transition induced by the strong polarization of the electrons due to local magnetic moments. The self - consistent Renormalization - Group methods have been used to calculate the temperature dependence of the electrical resistivity and specific heat. The T^{5/3} dependence o

A. A. Muench, E. A. Lada, C. J. Lada, R. J. Elston

We present wide-field near-infrared (JHK) images of the young, 2 Myr IC 348 cluster taken with FLAMINGOS. We use these new data to construct an infrared census of sources, which is sensitive enough to detect a 10 Mjup brown dwarf seen through an extinction of Av=7mag. We examine the cluster's structure and relationship to the molecular cloud and construc

I. J. Odwyer, Y. -H. Chu, R. A. Gruendl, M. A. Guerrero

We have used the WGACAT to search for hard X-ray sources associated with white dwarfs (WDs) from the catalog of McCook & Sion (1999). We find 17 X-ray sources coincident with WDs showing significant hard X-ray emission at energies >0.5 keV. Twelve of these WDs are in known binary systems, in two of which the accretion of the close companion's material on

R. R. Gal, R. R. de Carvalho, P. A. A. Lopes, S. G. Djorgovski

We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the Digitized Second Palomar Observatory Sky Survey (DPOSS). This cluster catalog, derived from the best calibrated plates in the high latitude (|b|>30) Northern Galactic Cap region, covers 5,800 square degrees, and contains 8,155 candidate clusters.

F. R. Ferraro

I report on some recent results in the framework of a complex project aimed to characterize the photometric properties of stellar populations in Galactic Globular Clusters.

Giuliano Taffoni, Lucio Mayer, Monica Colpi, Fabio Governato

We study the evolution of dark matter satellites orbiting inside more massive haloes using semi-analytical tools coupled with high-resolution N-Body simulations. We select initial satellite sizes, masses, orbital energies, and eccentricities as predicted by hierarchical models of structure formation. Both the satellite and the main halo are described by a Na

J. A. Eisner, B. F. Lane, R. L. Akeson, L. A. Hillenbrand

We have observed the Herbig Ae/Be sources AB Aur, VV Ser, V1685 Cyg (BD+40 4124), AS 442, and MWC 1080 with the Palomar Testbed Interferometer, obtaining the longest baseline near-IR interferometric observations of this class of objects. All of the sources are resolved at 2.2 microns with angular size scales generally <5 mas, consistent with the only previou

E. Berger, S. R. Kulkarni, D. A. Frail

We present a comprehensive sample of X-ray observations of 41 gamma-ray burst (GRB) afterglows, as well as jet opening angles, θ_j for a subset with measured jet breaks. We show that there is a significant dispersion in the X-ray fluxes, and hence isotropic X-ray luminosities (L_{X,iso}), normalized to 10 hr. However, there is a strong correlation between L_

K. O&#39;Neil, S. Andreon, J. -C. Cuillandre

The surface brightness distribution (SBD) function describes the number density of galaxies as measured against their central surface brightness. Because detecting galaxies with low central surface brightnesses is both time-consuming and complicated, determining the shape of this distribution function can be difficult. In a recent paper Cross, et al. suggest

Lifan Wang, D. Baade, P. Hoeflich, J. C. Wheeler

We present spectropolarimetry observations of GRB 021004 obtained at the ESO VLT. We detect a remarkable increase of the degree of polarization blueward of the host galaxy rest frame Ly-alpha to about 5-10% that corresponds to a decrease in the continuum flux below the extrapolation of a power law. An increase of the degree of polarization is perhaps also re

T. Elperin, N. Kleeorin, I. Rogachevskii

An effect of a mean velocity shear on a turbulence and on the effective force which is determined by the gradient of Reynolds stresses is studied. Generation of a mean vorticity in a homogeneous incompressible turbulent flow with an imposed mean velocity shear due to an excitation of a large-scale instability is found. The instability is caused by a combined

L. G. Balazs, Z. Bagoly, I. Horvath, A. Meszaros

We argue that the distributions of both the intrinsic fluence and the intrinsic duration of the gamma-ray emission in gamma-ray bursts from the BATSE sample are well represented by log-normal distributions, in which the intrinsic dispersion is much larger than the cosmological time dilatation and redshift effects. We perform separate bivariate log-normal dis

Francesco R. Ferraro, Alison Sills, Robert T. Rood, Barbara Paltrinieri

The central regions of six Galactic Globular Clusters (GGCs) (M3, M80, M10, M13, M92 and NGC 288) have been imaged using HST-WFPC2 and the ultraviolet (UV) filters (F255W, F336W). The selected sample covers a large range in both central density and metallicity ([Fe/H]). In this paper, we present a direct cluster-to-cluster comparison of the Blue Stragglers S

L. Rudnick, K. Blundell

We present a detailed examination of the relationship between the magnetic field structures and the variations in Faraday Rotation across PKS1246-410, a radio source in the Centaurus cluster of galaxies, using data from Taylor, Fabian and Allen. We find a significant relationship between the intrinsic position angle of the polarization and the local amount o

André Maeder, Georges Meynet

Rotation appears as a dominant effect in massive star evolution. It largely affects all the model outputs: inner structure, tracks, lifetimes, isochrones, surface compositions, blue to red supergiant ratios, etc. At lower metallicities, the effects of rotational mixing are larger; also, more stars may reach critical velocity, even if the initial distribution

André Maeder

We derive a new expression for the coefficient $D_{\mathrm{h}}$ of diffusion by horizontal turbulence in rotating stars. This new estimate can be up to two orders of magnitude larger than given by a previous expression. As a consequence the differential rotation on an equipotential is found to be very small, which reinforces Zahn&#39;s hypothesis of shellula

David Merritt

Massive central objects affect both the structure and evolution of galactic nuclei. Adiabatic growth of black holes generates power-law central density profiles with logarithmic slopes in the range from ~1.5 to ~2.5, in good agreement with the profiles observed in the nuclei of galaxies fainter than visual magnitude -20. However the shallow nuclear profiles

G. Ghisellini

The internal/external synchrotron shock scenario has proved very successful in interpreting the key observations about gamma ray bursts. There still remains, however, some big uncertainties. The hottest issue concerns the nature of the progenitor, but there are also other problems concerning the global energetics, coupled with the issue of the degree of the

Leslie K. Hunt, Trinh X. Thuan, Yuri I. Izotov

We present deep JHK images of IZw18, the most metal-deficient Blue Compact Dwarf galaxy known, and analyze them in conjunction with archival HST/WFPC2 optical images. To investigate the stellar populations, we have divided the main body of IZw18 into eight regions, and fit the optical, near-infrared (NIR), and hybrid optical-NIR colors of these and the C com

J. Bouwman, A. de Koter, C. Dominik, L. B. F. M Waters

We have investigated the spatial distribution, and the properties and chemical composition of the dust orbiting HD 100546. This system is remarkably different from other isolated Herbig Ae/Be stars in both the strength of the mid-IR excess and the composition of the circumstellar dust. We speculate that the formation and spatial distribution of the crystalli

R. P. Mignani, G. G. Pavlov, A. deLuca, P. A. Caraveo

New results of HST and VLT observations of isolated pulsars and their environments are presented. We present the first deep optical observations of the nearby pulsar PSR J0108-1431, the identification evidence of PSR 1929+10 based on the proper motion measurement of its optical counterpart and a deep investigation at optical wavelengths of the X-ray PWN arou

S. Ferraz-Mello, C. Beauge, T. A. Michtchenko

In this paper we present numerical simulations of the evolution of planets or massive satellites captured in the 2/1 and 3/1 resonances, under the action of an anti-dissipative tidal force. The evolution of resonant trapped bodies show a richness of solutions: librations around stationary symmetric solutions with aligned periapses (w1-w2=0) or anti-aligned p

Keith Horne

We discuss technologies for micro-arcsec echo mapping of black hole accretion flows in Active Galactic Nuclei (AGN). Echo mapping employs time delays, Doppler shifts, and photoionisation physics to map the geometry, kinematics, and physical conditions in the reprocessing region close to a compact time-variable source of ionizing radiation. Time delay maps ar

J. A. de Freitas Pacheco, R. Michard, R. Mohayaee

A review of the present observational and theoretical status of elliptical galaxies is presented with the aim to clarify whether the monolithic or the hierarchical, is a more viable scenario for the origin of these structures. We describe the dynamical structure of elliptical galaxies using photometric and spectroscopic data, in particular 3D observations fr

A. V. Maccio&#39;, G. Murante, S. A. Bonometto

We show that DM halos, in n--body simulations, have a boundary layer (BL), separating bound from unbound mass. Let T(r) and W(r) be the kinetic and potential energies in shells of halos. We find that, in almost all halos: (i) The virial ratio R=-2T/W has at least one persistent (i.e. resolution independent) minimum r_c, such that, close to it, (ii) the funct

Sylvie Theado, Sylvie Vauclair

In the first paper of this series, we discussed analytically, in an approximate way, the mixing processes which occur in slowly rotating stars when the feed-back effects due to the diffusion-induced $μ$-gradients are introduced in the computations. We found that the classical scheme of meridional circulation was dramatically modified, with important possible

P. R. den Hartog, J. J. M. in &#39;t Zand, E. Kuulkers, R. Cornelisse

GX 3+1 is a low-mass X-ray binary that is persistently bright since its discovery in 1964. It was found to be an X-ray burster twenty years ago proving that the compact object in this system is a neutron star. The burst rate is so low that only 18 bursts were reported prior to 1996. The Wide Field Cameras on BeppoSAX have, through a dedicated monitoring prog

F. R. Ferraro, E. Sabbi, R. Gratton, A. Possenti

By means of high-resolution spectra we have measured radial velocities of the companion (hereafter COM J1740-5340) to the eclipsing millisecond pulsar PSR J1740-5340 in the Galactic globular cluster NGC 6397. The radial-velocity curve fully confirms that COM J1740-5340 is orbiting the pulsar and enables us to derive the most accurate mass ratio (M_ PSR/M_COM

H. Quaintrell, A. J. Norton, T. D. C. Ash, P. Roche

We report new radial velocity observations of GP Vel/HD77581, the optical companion to the eclipsing X-ray pulsar Vela X-1. Using data spanning more than two complete orbits of the system, we detect evidence for tidally induced non-radial oscillations on the surface of GP Vel, apparent as peaks in the power spectrum of the residuals to the radial velocity cu

Yinon Arieli, Yoel Rephaeli

There are some basic differences between the observed properties of galaxies and clusters and the predictions from current hydrodynamical simulations. These are particularly pronounced in the central regions of galaxies and clusters. The popular NFW (Navarro, Frenk, and White) profile, for example, predicts a density cusp at the center, a behavior that (unsu

Patrick A. Woudt, Brian Warner

We present further results from a high speed photometric survey of faint cataclysmic variables. We find that V842 Cen (Nova Cen 1986 No. 2) is highly active, but with no evident orbital modulation. BY Cir (Nova Cir 1995) is an eclipsing system with an orbital period P(orb) of 6.76 h. TV Crv, an SU UMa type dwarf nova, is found to have P(orb) = 1.509 h from p

V. R. Chitnis, P. N. Bhat

In the atmospheric Cerenkov technique gamma rays are detected against the abundant background produced by hadronic showers. In order to improve the signal to noise ratio of the experiment, it is necessary to reject a significant fraction of hadronic showers. Traditional background rejection methods based on image shape parameters have been extensively used f

Roberto Abraham, Sidney van den Bergh, Preethi Nair

In this paper we present a new statistic for quantifying galaxy morphology based on measurements of the Gini coefficient of galaxy light distributions. This statistic is easy to measure and is commonly used in econometrics to measure how wealth is distributed in human populations. When applied to galaxy images, the Gini coefficient provides a quantitative me

A. Lobel, A. K. Dupree, R. P. Stefanik, G. Torres

We present an overview of the spectral variability of the peculiar F-type hypergiant Rho Cas, obtained from our long-term monitoring campaigns over the past 8.5 years with four spectrographs in the northern hemisphere. Between 2000 June and September an exceptional variability phase occurred when the V-brightness dimmed by about a full magnitude. The star re