August 2000 arXiv papers — page 9

A. K. Mitra, R. L. Poirier, R. E. Laxdal

The high energy beam transport (HEBT) line for the ISAC radioactive beam facility at TRIUMF requires an 11.8 MHz buncher. The main requirements of the buncher are to operate in cw mode with a velocity acceptance of 2.2% and an effective voltage of 100 kV, which for a three gap buncher gives a drift tube voltage of 30 kV. A lumped element circuit is more suit

Robert L. Kustom

The Spallation Neutron Source (SNS) is being designed, constructed, installed and commissioned by the staff of six national laboratories, Argonne National Laboratory, Brookhaven National Laboratory, Jefferson National Accelerator Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, and Oak Ridge National Laboratory. The accelera

R. M. Jones, N. M. Kroll, R. H. Miller, C. K. Ng

In damping the wakefield generated by an electron beam traversing several thousand X-band linacs in the NLC we utilise a Gaussian frequency distribution of dipole modes to force the modes to deconstructively interfere, supplemented with moderate damping achieved by coupling these modes to four attached manifolds. Most of these modes are adequately damped by

R. L. Poirier, R. Baartman, P. Bricault, K. Fong

The ISAC 35 MHz RFQ is designed to accelerate ions of A/q up to 30 from 2keV/u to 150keV/u in cw mode. The RFQ structure is 8 meters long and the vane-shaped rods are supported by 19 rings spaced 40 cm apart. An unusual feature of the design is the constant synchronous phase of -25; the buncher and shaper sections are eliminated in favor of an external multi

A. Kolomiets, S. Yaramishev

The conception of High Power Linac developed in Russian accelerator centres is based on the use of independently phased SC resonators with quadrupole lenses between them. The type and parameters of the resonators as well as focusing structure are varied along the linac to optimise beam dynamics and the characteristics of the linac. The beam evolution in the

G. D'Auria, C. Rossi, M. Danailov, M. Ferrario

A program to design a high brilliance electron source suitable for a short wavelength Linac-based FEL is presented. The goal of the project is to develop a multi-cell integrated photoinjector capable of delivering 1 nC bunches with emittance below 1 mm mrad. This will be the first step toward a possible development of a IV generation light source test facili

I. Petras

This paper deals with feedback control of fractional-order Chua's system. The fractional-order Chua's system with total order less than three which exhibit chaos as well as other nonlinear behavior and theory for control of chaotic systems using sampled data are presented. Numerical experimental example is shown to verify the theoretical results.

S. A. Albeverio, P. Exner, V. A. Geyler

We consider a charged quantum particle living in the Lobachevsky plane and interacting with a homogeneous magnetic field perpendicular to the plane and a point interaction which is transported adiabatically along a closed loop C in the plane. We show that the bound-state eigenfunction acquires at that the Berry phase equal to 2πtimes the number of the flux q

Luca Salasnich

We investigate ideal quantum gases in D-dimensional space and confined in a generic external potential by using the semiclassical approximation. In particular, we derive density of states, density profiles and critical temperatures for Fermions and Bosons trapped in isotropic power-law potentials. Form such results, one can easily obtain those of quantum gas

Hyeong-Chai Jeong, Eunsang Kim, Chang-Yeong Lee

We classify the Fibonacci chains (F-chains) by their index sequences and construct an approximately finite dimensional (AF) $C^*$-algebra on the space of F-chains as Connes did on the space of Penrose tiling. The K-theory on this AF-algebra suggests a connection between the noncommutative torus and the space of F-chains. A noncommutative torus, which can be

Greg Martin

Although we expect to find many smooth numbers (i.e., numbers with no large prime factors) among the values taken by a polynomial with integer coefficients, it is unclear what the asymptotic number of such smooth values should be; this is in contrast to the related problem of counting the number of prime values of a polynomial, for which Bateman and Horn pub

Ronald Brown, Ilhan Içen

The notion of local equivalence relation on a topological space is generalised to that of local subgroupoid. The main result is the construction of the holonomy and monodromy groupoids of certain Lie local subgroupoids, and the formulation of a monodromy principle on the extendibility of local Lie morphisms.

Eugene Lerman, Christopher Willett

We show that if a Lie group acts properly on a co-oriented contact manifold preserving the contact structure, then the contact quotient is topologically a stratified space (in the sense that a neighborhood of a point in the quotient is a product of a disk with a cone on a compact stratified space). As a corollary, we obtain that symplectic quotients for prop

Eduardo Esteves, Letterio Gatto

In the 80's M. Cornalba and J. Harris discovered a relation among the Hodge class and the boundary classes in the Picard group with rational coefficients of the moduli space of stable, hyperelliptic curves. They proved the relation by computing degrees of the classes involved for suitable one-parameter families. In the present article we show that their

P. G. Casazza, M. C. Lammers

We examine the question of which characteristic functions yield Weyl-Heisenberg frames for various values of the parameters. We also give numerous applications of frames of characteristic functions to the general case (g,a,b).

Peter G. Casazza, Ole Christensen, Mark C. Lammers

We develop a usable perturbation theory for Weyl-Heisenberg frames. In particular, we prove that if $(E_{mb}T_{na}g)_{m,n\inmathbb Z}$ is a WH-frame and $h$ is a function which is close to $g$ in the Wiener Amalgam space norm, then $(E_{mb}T_{na}h)_{m,n\in \mathbb Z}$ is also a WH-frame.

Cristopher Moore, David Eppstein

We solve the problem of one-dimensional Peg Solitaire. In particular, we show that the set of configurations that can be reduced to a single peg forms a regular language, and that a linear-time algorithm exists for reducing any configuration to the minimum number of pegs. We then look at the impartial two-player game, proposed by Ravikumar, where two players

Nic Ormes, Charles Radin, Lorenzo Sadun

We derive a homeomorphism invariant for those tiling spaces which are made by rather general substitution rules on polygonal tiles, including those tilings, like the pinwheel, which contain tiles in infinitely many orientations. The invariant is a quotient of Cech cohomology, is easily computed directly from the substitution rule, and distinguishes many exam

Bert van Geemen, Elham Izadi

A Hodge structure V of weight k on which a CM field acts defines, under certain conditions, a Hodge structure of weight k-1, its half twist. In this paper we consider hypersurfaces in projective space with a cyclic automorphism which defines an action of a cyclotomic field on a Hodge substructure in the cohomology. We determine when the half twist exists and

Christopher P. Bendel

Let G be a finite group scheme over an algebraically closed field of positive characteristic. Assume further that the connected component of G is unipotent. It is shown that the projectivity of a rational G-module can be detected on a family of closed subgroups. It is further shown that nilpotent cohomology or extension classes can be detected on this family

Christopher P. Bendel

In this paper, it is shown that the projectivity of a rational module for an infinitesimal unipotent group scheme over an algebraically closed field of positive characteristic can be detected on a family of closed subgroups.

Mike Zabrocki

Given a partition $\la = (\la_1, \la_2, ... \la_k)$, let $\la^{rc} = (\la_2-1, \la_3-1, ... \la_k-1)$. It is easily seen that the diagram $\la\slash \la^{rc}$ is connected and has no $2 \times 2$ subdiagrams which we shall refer to as a ribbon. To each ribbon $R$, we associate a symmetric function operator $S^R$. We may define the major index of a ribbon $ma

Yanguang Charles Li

A Lax pair for the 2D Euler equation is found.

C. N. Ferreira, H. J. Mosquera-Cuesta, L. C. Garcia de Andrade

We show that it is possible to construct a consistent model describing a current-carrying cosmic string endowed with torsion. The torsion contribution to the gravitational force and geodesics of a test-particle moving around the SCCS are analyzed. In particular, we point out two interesting astrophysical phenomena in which the higher magnitude force we deriv

A. Bassetto, L. Griguolo, F. Vian

Two-dimensional SU(N) Yang-Mills theory is endowed with a non-trivial vacuum structure (k-sectors). The presence of k-sectors modifies the energy spectrum of the theory and its instanton content, the (Euclidean) space-time being compactified on a sphere. For the exact solution, in the limit in which the sphere is decompactified, a k-sector can be mimicked by

Verena Schoen, Michael Thies

In certain 1+1 dimensional field theoretic toy models, one can go all the way from microscopic quarks via the hadron spectrum to the properties of hot and dense baryonic matter in an essentially analytic way. This "miracle" is illustrated through case studies of two popular large N models, the Gross-Neveu and the 't Hooft model - caricatures of t

I. L. Buchbinder

We review a recent progress in constructing low-energy effective action in N=4 super Yang-Mills theories. Using harmonic superspace approach we consider N=4 SYM in terms of unconstrained N=2 superfield and apply N=2 background field method to finding effective action for N=4 SU(n) SYM broken down to U(n)$^{n-1}$. General structure of leading low-energy corre

H. K. Jassal, A. Mukherjee

This paper presents a detailed investigation of the motion of a string near a Kaluza-Klein black hole, using the null string expansion. The zeroth-order string equations of motion are set up separately for electrically and magnetically charged black hole backgrounds. The case of a string falling head-on into the black hole is considered in detail. The equati

Itzhak Bars

Two-time physics (2T) is a general reformulation of one-time physics (1T) that displays previously unnoticed hidden symmetries in 1T dynamical systems and establishes previously unknown duality type relations among them. This may play a role in displaying the symmetries and constructing the dynamics of little understood systems, such as M-theory. 2T physics

J. S. Dowker

The hybrid spectral problem where the field satisfies Dirichlet conditions (D) on part of the boundary of the relevant domain and Neumann (N) on the remainder is discussed in simple terms. A conjecture for the C_1 coefficient is presented and the conformal determinant on a 2-disc, where the D and N regions are semi-circles, is derived. Comments on higher coe

Jen-Chi Lee

We calculate the R-R zero-norm states of type II string spectrum. To fit these states into the right symmetry charge parameters of the gauge transformations of the R-R tensor forms, one is forced to T-dualize some type I open string space-time coordinates and thus to introduce D-branes into the theory. We also demonstrate that the constant T-dual R-R 0-form

Jusak Tandean, G. Valencia

We present a reanalysis of direct CP violation in the decay K_L -> pi^+ pi^- gamma. We point out an existing discrepancy between the theoretical and experimental definitions of epsilon'_{+-gamma}. Adopting the experimental definition of epsilon'_{+-gamma}, we estimate that epsilon'_{+-gamma}/epsilon could be as large as a few times 10^{-4} both w

Adam K Leibovich

Most recent calculations of quarkonium production are based on the NRQCD factorization formalism. This formalism is reviewed. To make predictions about specific cross section, universal NRQCD matrix elements need to be extracted from experiments. Extractions from different experimental situations are compared, with some emphasis on the extraction from LEP.

Chueng-Ryong Ji, Ho-Meoyng Choi

Theoretical overviews on the B-physics are presented with an emphasis on the light-cone degrees of freedom. Our new treatment of the embedded states seems to give an encouraging result.

Thomas DeGrand

These lectures (given at TASI 2000) provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1 (Ch. 2) is a very vanilla introduction to lattice QCD. Lecture 2 (Ch. 3) describes examples of recent lattice calculations relevant to fixing the parameters of the CKM matrix.

S. R. Juarez W., F. Guzman A.

Very accurate analytical expressions for the radiative corrections of unpolarized hyperons semileptonic decays of charged and neutral baryons have been obtained in the recent past. Some of these formulas contain logarithmic singularities at the edges of the Dalitz plot for the three- and four-body decays. These singularities are analyzed and integrated analy

A. K. Likhoded, S. R. Slabospitsky

We present the calculation of the inclusive $x_F$-distributions of charmed hadrons, produced in high-energy $Σ^-$-beam. The calculation is based on the modified mechanism of charmed quarks fragmentation as well as on the mechanism of $c$-quark recombination with the valence quarks from initial hadrons. We predict the additional asymmetry in the production of

Carlo Ewerz

I give a brief account of Gribov's scenario of supercritical charges in QCD. Gribov's equation for the Green function of light quarks and its derivation from the corresponding Dyson-Schwinger equation are described. The resulting Green function is shown to exhibit chiral symmetry breaking.

Savely G. Karshenboim

Recently, a precise measurement on the bound electron g factor in hydrogen-like carbon was performed [1]. We consider the present status of the theory of the g factor of an electron bound in a hydrogen-like atom and discuss new opportunities and possible applications of the recent experiment.

Yosef Nir

We review various implications of recent experimental results concerning CP violation and mixing in $K\toππ$, $B\toψK_S$, $D\to Kπ$ and $D\to KK$ decays.

K. Terasaki

The hypothesis of sigma meson pole dominance in the Delta I = 1/2 K -> pi pi amplitudes is tested by using the K_L-K_S mass difference.

J. Belz, the KTeV Collaboration

We have perfomed studies of the KL to PI+PI-GAMMA Direct Emission (DE) and Inner Bremsstrahlung (IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a1/a2 = -0.737 +- 0.034 GeV^2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form-factor to linear and quadratic fu

Kate Scholberg

World-wide, several detectors currently running or nearing completion are sensitive to a core collapse supernova neutrino signal in the Galaxy. I will briefly describe the nature of the neutrino signal and then survey current and future detection techniques. I will also explore what physics and astrophysics we can learn from the next Galactic core collapse.

Pierre Van Mechelen

Recent experimental results on diffractive high $E_T$ jet production and diffractive open charm production, obtained by the H1 and ZEUS experiments at HERA, are presented. Various theoretical models for diffractive hard scattering are discussed and confronted with the experimental data.

V. F. Andreev, A. S. Belousov, A. M. Fomenko, L. A. Gorbov

The H1 detector at HERA has been upgraded by the addition of a new electromagnetic calorimeter. This is installed in the HERA tunnel close to the electron beam line at a position 8m from the interaction point in the electron beam direction. The new calorimeter extends the acceptance for tagged photoproduction events to the high y range, 0.85 < y < 0.95, and

Zhong Chao Wu

In gravitational thermodynamics, the origin of a black hole&#39;s entropy is the topology of its instanton or constrained instanton. We prove that the entropy of an arbitrary nonrotating black hole is one quarter the sum of the products of the Euler characteristics of its horizons with their respective areas. The Gauss-Bonnet-like form of the action is not o

Alexander Burinskii, Giulio Magli

Using a complex representation of the Debney-Kerr-Schild (DKS) solutions and the Kerr theorem we give a method to construct boosted Kerr geometries. In the ultrarelativistic case this method yelds twisting solutions having, contrary to the known pp-wave limiting solutions, a non-zero value of the total angular momentum. The solutions show that twist plays a

Martin Bojowald

An angular momentum operator in loop quantum gravity is defined using spherically symmetric states as a non-rotating reference system. It can be diagonalized simultaneously with the area operator and has the familiar spectrum. The operator indicates how the quantum geometry of non-rotating isolated horizons can be generalized to rotating ones and how the rec

Martin Bojowald

Using general features of recent quantizations of the Hamiltonian constraint in loop quantum gravity and loop quantum cosmology, a dynamical interpretation of the constraint equation as evolution equation is presented. This involves a transformation from the connection to a dreibein representation and the selection of an internal time variable. Due to the di

Martin Bojowald

In the framework of loop quantum cosmology anomaly free quantizations of the Hamiltonian constraint for Bianchi class A, locally rotationally symmetric and isotropic models are given. Basic ideas of the construction in (non-symmetric) loop quantum gravity can be used, but there are also further inputs because the special structure of symmetric models has to

Marcia Muñoz, Vasin Punyakanok, Dan Roth, Dav Zimak

A SNoW based learning approach to shallow parsing tasks is presented and studied experimentally. The approach learns to identify syntactic patterns by combining simple predictors to produce a coherent inference. Two instantiations of this approach are studied and experimental results for Noun-Phrases (NP) and Subject-Verb (SV) phrases that compare favorably

Mark Johnson, Brian Roark

The left-corner transform removes left-recursion from (probabilistic) context-free grammars and unification grammars, permitting simple top-down parsing techniques to be used. Unfortunately the grammars produced by the standard left-corner transform are usually much larger than the original. The selective left-corner transform described in this paper produce

Massimiliano Ciaramita, Mark Johnson

This paper presents a Bayesian model for unsupervised learning of verb selectional preferences. For each verb the model creates a Bayesian network whose architecture is determined by the lexical hierarchy of Wordnet and whose parameters are estimated from a list of verb-object pairs found from a corpus. ``Explaining away&#39;&#39;, a well-known property of B

Ion Androutsopoulos, John Koutsias, Konstantinos V. Chandrinos, Constantine D. Spyropoulos

The growing problem of unsolicited bulk e-mail, also known as &#34;spam&#34;, has generated a need for reliable anti-spam e-mail filters. Filters of this type have so far been based mostly on manually constructed keyword patterns. An alternative approach has recently been proposed, whereby a Naive Bayesian classifier is trained automatically to detect spam m

G. Senizergues

The &#34;bisimulation problem&#34; for equational graphs of finite out-degree is shown to be decidable. We reduce this problem to the bisimulation problem for deterministic rational (vectors of) boolean series on the alphabet of a dpda M. We then exhibit a complete formal system for deducing equivalent pairs of such vectors.

R. H. Blick, F. G. Monzon, W. Wegscheider, M. Bichler

We present magnetotransport measurements on freely suspended two-dimensional electron gases from AlGaAs/GaAs heterostructures. The technique to realize such devices relies on a specially MBE grown GaAs/AlGaAs-heterostructure including a sacrificial layer. We fabricated simple Hall-bars as well as quantum cavities and quantum dot systems. We find well-pronoun

Leo Radzihovsky, Tom Lubensky

Motivated in part by recent experiments on liquid crystals with bent-core molecules, which are observed to display a spontaneous chiral symmetry breaking, we introduce a field theory of a 3rd-rank tensor order parameter T^{ijk} to describe the isotropic-to-tetrahedratic phase transition that we predict to take place in these materials. We study the critical

Y. Yourdshahyan, H. K. Zhang, A. M. Rappe

State-of-the-art first principles calculations based on density functional theory were performed on CH_3(CH_2)_{n-1}S-Au(111) systems. We show that the adsorption site of methylthiolate at low coverage on the Au(111) surface is the fcc site, not the hcp site as has been recently reported. Further, we report results for chain length dependency and the electro

V. Yushankhai, P. Thalmeier

A theory of superexchange in the mixed valent layer compound NaV2O5 is presented which provides a consistent description of exchange both in the disordered and charge ordered state. Starting from results of band structure calculations for NaV2O5 first an underlying electronic model for a ladder unit in the Trellis lattice is formulated. By using the molecula

A. K. Kolezhuk, H. -J. Mikeska, U. Schollwoeck

We study, both numerically and variationally, the interplay between different types of elementary excitations in the model of a spin chain with anisotropic spin-orbit coupling, in the vicinity of the &#34;dimer line&#34; with an exactly known dimerized ground state. Our variational treatment is found to be in a qualitative agreement with the exact diagonaliz

N. Nücker, M. Merz, C. A. Kuntscher, S. Gerhold

The unoccupied electronic structure for the Sr_14Cu_24O_41 family of two-leg ladder compounds was investigated for different partial substitutions of Sr^2+ by Ca^2+, leaving the nominal hole count constant, and by Y^3+ or La^3+, reducing the nominal hole count from its full value of 6 per formula unit. Using polarization-dependent x-ray absorption spectrosco

Nir Gov

In this work we investigate the quantum nature of bcc $^{4}$He. We show that it is a solid phase with an Off-Diagonal Long Range Order of coherently oscillating local electric dipole moments. These dipoles arise from the correlated zero-point motion of the atoms in the crystal potential, which oscillate in synchrony so that the dipolar interaction energy is

N. Gov, E. Polturak

We propose a new way to treat nuclear magnetism of solid $^{3}$He. We argue that the magnetic interaction arises indirectly as a consequence of correlated zero-point motion of the ions. This motion lowers the energy of the ground state, and results in a coherent state of oscillating electric dipoles. Distortion of the electronic wavefunctions leads to hyperf

Eric R. Dufresne, David Altman, David G. Grier

We describe direct imaging measurements of a colloidal sphere&#39;s diffusion between two parallel surfaces. The dynamics of this deceptively simple hydrodynamically coupled system have proved difficult to analyze. Comparison with approximate formulations of a confined sphere&#39;s hydrodynamic mobility reveals good agreement with both a leading-order superp

V. R. Manfredi, L. Salasnich

In the field of quantum chaos, the study of energy levels plays an important role. The aim of this review paper is to critically discuss some of the main contributions regarding the connection between classical dynamics, semi-classical quantization and spectral statistics of energy levels. In particular, we analyze in detail degeneracies and quasi-crossings

R. R. Levitskii, A. P. Moina, B. M. Lisnii

We verify whether the previously developed model of a KD2PO4 crystal, with the shear strain eps6 taken into account, is able to describe the longitudinal electric field E3 influence on the KH2PO4 family ferroelectrics. Major effects of the strain eps6 are splitting of the Slater energies of the short-range correlations and the effective field created by piez

Ryszard Piasecki

We consider the relative configurational entropy per cell S_Delta as a measure of the degree of spatial disorder for systems of finite-sized objects. It is highly sensitive to deviations from the most spatially ordered reference configuration of the objects. When applied to a given binary image it provides the quantitatively correct results in comparison to

Oscar Iglesias, Felix Ritort, Amilcar Labarta

We present the results of Monte Carlo simulations of a model of a $γ$-Fe$_2$ O$_3$ (maghemite) single particle of spherical shape. The magnetic Fe$^{3+}$ ions are represented by Ising spins on a spinel lattice that consists on two sublattices with octhaedral and tetrahedral coordination with exchange interactions among them and with an external magnetic fiel

Gyorgy Szabo, Tamas Czaran

Spatial evolution is investigated in a simulated system of nine competing and mutating bacterium strains, which mimics the biochemical war among bacteria capable of producing two different bacteriocins (toxins) at most. Random sequential dynamics on a square lattice is governed by very symmetrical transition rules for neighborhood invasion of sensitive strai

Gyorgy Szabo

The branching annihilating random walk is studied on a random graph whose sites have uniform number of neighbors (z). The Monte Carlo simulations in agreement with the generalized mean-field analysis indicate that the concentration decreses linearly with the branching rate for $z \ge 4$ while the coefficient of the linear term becomes zero if $z=3$. These fe

Jun-ichi Igarashi, Manabu Takahashi

We analyze the recent experiment [W. Neubeck {\em et al.}, Phys. Rev. B \vol(60,1999,R9912)] for the resonant x-ray magnetic scattering (RXMS) around the K edge of Co in the antiferromagnet CoO. We propose a mechanism of the RXMS to make the $4p$ states couple to the magnetic order: the intraatomic exchange interaction between the $4p$ and the $3d$ states an

David H. Cohen, Joseph P. Cassinelli, Joseph J. MacFarlane, Stanley P. Owocki

We discuss the EUV and X-ray properties of B stars, focusing on $ε$ CMa (B2 II) which is the only star with both emission lines and a photospheric continuum detected with EUVE. We explore the modest effects of the photospheric EUV continua on the wind, as well as the much stronger effects of the short-wavelength EUV and soft X-ray emission lines. Attenuation

Priya Jamkhedkar, Hu Zhan, Li-Zhi Fang

The intermittent behavior of the space-scale distribution of Ly$α$ transmitted flux of QSO HS1700+64 has been analyzed via a discrete wavelet transform. We found that there are strong indications of intermittency on scales down to about 10 $h^{-1}$ kpc. These are: 1.) the probability distribution function of the local fluctuations of the flux is significantl

Frits Paerels, A. C. Brinkman, R. L. J. van der Meer, J. S. Kaastra

We find resolved interstellar O K, Ne K, and Fe L absorption spectra in the Chandra Low Energy Transmission Grating Spectrometer spectrum of the low mass X-ray binary X0614+091. We measure the column densities in O and Ne, and find direct spectroscopic constraints on the chemical state of the interstellar O. These measurements probably probe a low-density li

G. Bernstein, B. Khushalani

We present a procedure for determination of positions and orbital elements, and associated uncertainties, of outer Solar System planets. The orbit-fitting procedure is greatly streamlined compared to traditional methods because acceleration can be treated as a perturbation to the inertial motion of the body. These techniques are immediately applicable to Kui

Fabian Walter, Andreas Heithausen

Using the IRAM 30m radio telescope we have mapped the tidal arm feature south-east of NGC 3077 where we recently detected molecular gas in the CO (1-0) and (2-1) transitions. We find that the molecular gas is much more extended than previously thought (several kpc). The CO emission can be separated into at least 3 distinct complexes with equivalent radii bet

David H. Cohen

I discuss the X-ray observations of Be stars, and how their properties compare to non-emission B stars. I focus on several specific stars that show high flux levels and variability but also report on several interesting survey results. The Be X-ray properties are discussed in the context of wind-shock X-ray emission from normal OB stars as well as in the con

Jean P. Brodie, Soeren S. Larsen, Markus Kissler-Patig

NGC 3311, the central cD galaxy in the Hydra cluster, was previously thought to host the most metal-rich globular cluster system known. Ground-based Washington photometry had indicated the almost complete absence of the population of globular clusters near [Fe/H] ~ -1 dex, normally dominant in the metallicity distribution functions of giant elliptical galaxi

J. Dennett-Thorpe, M. J. Marcha

This paper concerns the relationship of BLLacs and flat spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BLLacs in a sample of 57 flat spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices and polarization properties. We consider whether objects which

G. Giovannini, L. Feretti

New images of 7 radio halos and relics, obtained with the Very Large Array at 20 or 90 cm, are presented here. The existence of a cluster-wide radio halo in the clusters A 665 and CL 0016+16 is confirmed. Both these clusters share the properties of the other clusters with radio halos, i.e. are luminous in X-rays, have high temperature, and show recent merger

F. Combes

Non-axisymmetric modes like spirals and bars are the main driver of the evolution of disks, in transferring angular momentum, and allowing mass accretion. This evolution proceeds through self-regulation and feedback mechanisms, such as bar destruction or weakening by a central mass concentration, decoupling of a nuclear bar taking over the gas radial flows a

R. Tuellmann, R. -J. Dettmar

In order to examine the excitation and ionization mechanism of extraplanar diffuse ionized gas (DIG) we have obtained optical longslit spectra of seven edge-on spiral galaxies. In four objects the brightest emission lines can be traced out to distances of typically 1.5 kpc above the disk. For NGC1963 and NGC3044 line ratios such as [NII]6583/Ha or [SII]6717/

L. Baudis, A. Dietz, B. Majorovits, F. Schwamm

The Heidelberg Dark Matter Search Experiment (HDMS) is a new ionization Germanium experiment in a special design. Two concentric Ge crystals are housed by one cryostat system, the outer detector acting as an effective shield against multiple scattered photons for the inner crystal, which is the actual dark matter target. We present first results after succes

Kumi Yoshita, Emi Miyata, Hiroshi Tsunemi

We discovered a middle-aged supernova remnant (SNR) in the vicinity of G69.7+1.0 using the ASCA satellite. G69.7+1.0 was identified in the 2.7 GHz survey and classified as a shell-type SNR with a diameter of 16 arcmin. During the ROSAT all-sky survey, the X-ray emission was detected in the direction of G69.7+1.0. However, it extends beyond the radio shell, a

M. Carmeli, S. Behar

Recent observations of distant supernovae imply, in defiance of expectations, that the universe growth is accelerating, contrary to what has always been assumed that the expansion is slowing down due to gravity. In this paper a general-relativistic cosmological theory that gives a direct relationship between distances and redshifts in an expanding universe i

M. Tosi

The major effects of the chemical evolution of galaxies on the characteristics of their stellar populations are reviewed. A few examples of how the observed stellar properties derived from colour--magnitude diagrams can constrain chemical evolution models are given.

Kin-Wing Chan, T. L. Roellig, T. Onaka, M. Mizutani

Using the Mid-Infrared Spectrometer on board the Infrared Telescope in Space and the low-resolution grating spectrometer (PHT-S) on board the Infrared Space Observatory, we obtained 820 mid-infrared (5 to 12 $μ$m) spectra of the diffuse interstellar medium (DIM) in the Galactic center, W51, and Carina Nebula regions. These spectra indicate that the emission

V. Folomeev, V. Gurovich, R. Usupov

In the modern Universe the existence of various forms of scalar fields is supposed. On the one hand these fields can explain recently discovered positive $Λ$-term(see e.g. Ref. \cite{ref:Sahni}), on the other hand its form cluster systems creating gravitational wells for galaxies and their clusters. At that a natural hypothesis is the existence of compact co

Klaus Dolag, Torsten A. Ensslin

We investigate the possibility that radio halos of clusters of galaxies are caused by synchrotron emission of cosmic ray electrons (CRe), which were produced by cosmic ray protons (CRp) interacting hadronically with the intra-cluster medium (ICM) protons. We perform cosmological magneto-hydrodynamics (MHD) simulations to obtain a sample of ten magnetized gal

Cheongho Han, Yong-Gi Kim

There are two different strategies of followup observations for the detection of planets by using microlensing. One is detecting the light curve anomalies affected by the planetary caustic from continuous monitoring of all events detected by microlensing survey programs (type I strategy) and the other is detecting anomalies near the peak amplification affect

Masaaki Sakano, Ken&#39;ichi Torii, Katsuji Koyama, Yoshitomo Maeda

We report the discovery of an X-ray pulsar AX J1740.1-2847 from the Galactic center region. This source was found as a faint hard X-ray object on 7--8 September 1998 with the ASCA Galactic center survey observation. Then, coherent pulsations of P=729 +/- 14 sec period were detected. The X-ray spectrum is described by a flat power-law of ~= 0.7 photon index.

Andreas Albrecht

I review the current status of the theory of Cosmic Inflation. My discussion covers the motivation and implementation of the idea, as well as an analysis of recent successes and open questions. There is a special discussion of the physics of ``cosmic coherence&#39;&#39; in the primordial perturbations. The issue of coherence is at the heart of much of the su

F. Hautmann, D. E. Soper

We suggest a simple physical picture for the diffractive parton distributions that appear in diffractive deeply inelastic scattering. In this picture, partons impinging on the proton can have any transverse separation, but only when the separation is small can they penetrate the proton without breaking it up. By comparing the predictions from this picture wi

Paul Martini

I present near-infrared J (1.25um), H (1.65um), and K (2.2um) imaging observations of 185 square arcminutes in 21 high galactic latitude fields. These observations reach limiting magnitudes of J ~ 21 mag, H ~ 20 mag and K ~ 18.5 mag. The detection efficiency, photometric accuracy and selection biases as a function of integrated object brightness, size, and p

Mario Eudave-Munoz, Jeremy Shor

It is shown that for given positive integers g and b, there is a number C(g,b), such that any orientable compact irreducible 3-manifold of Heegaard genus g has at most C(g,b) disjoint, nonparallel incompressible surfaces with first Betti number b_1 < b.

Qingshan Yuan, Takashi Yamamoto, Peter Thalmeier

The magnetic phase diagram of a two-dimensional generalized Hubbard model proposed for manganites is studied within Hartree-Fock approximation. In this model the hopping matrix includes anisotropic diagonal hopping matrix elements as well as off-diagonal elements. The antiferromagnetic (AF), ferromagnetic (F), canted (C) and paramagnetic (P) states are inclu

A. V. Radyushkin, C. Weiss

We compute the amplitude of deeply virtual Compton scattering (DVCS) using the calculus of QCD string operators in coordinate representation. To restore the electromagnetic gauge invariance (transversality) of the twist-2 amplitude we include the operators of twist-3 which appear as total derivatives of twist-2 operators. Our results are equivalent to a Wand

Anne M. Green

Currently the best prospect for detecting Weakly Interacting Massive Particles (WIMPs) is via the annual modulation, which occurs due to the Earth&#39;s rotation around the Sun, of the direct detection signal. We investigate the effect of uncertainties in our knowledge of the structure of the galactic halo on the WIMP annual modulation signal. We compare the

Matthias Koll, Ralf Ricken, Dirk Merten, Bernard Metsch

We present new results of a relativistic quark model based on the Bethe-Salpeter equation in its instantaneous approximation. Assuming a linearly rising confinement potential with an appropriate spinorial structure in Dirac space and adopting a residual interaction based on instanton effects, we can compute masses of the light mesons up to highest observed a

Adrian Dragulescu, Victor M. Yakovenko

Using tax and census data, we demonstrate that the distribution of individual income in the USA is exponential. Our calculated Lorenz curve without fitting parameters and Gini coefficient 1/2 agree well with the data. From the individual income distribution, we derive the distribution function of income for families with two earners and show that it also agr