September 2001 arXiv papers — page 14

A. Crisanti, F. Ritort, A. Rocco, M. Sellitto

We study three kinetic models with constraint, namely the Symmetrically Constrained Ising Chain, the Asymmetrically Constrained Ising Chain, and the Backgammon Model. All these models show glassy behavior and coarsening. We apply to them the Stillinger and Weber decomposition, and find that they share the same configurational entropy, despite of their differ

L. -A. Wu, D. A. Lidar

Qubits are neither fermions nor bosons. A Fock space description of qubits leads to a mapping from qubits to parafermions: particles with a hybrid boson-fermion quantum statistics. We study this mapping in detail, and use it to provide a classification of the algebras of operators acting on qubits. These algebras in turn classify the universality of differen

H. Jung

The application of k_t - factorization supplemented with the CCFM small-x evolution equation to heavy quark production is discussed. The b-b_bar production cross sections at the TEVATRON can be consistently described using the k_t-factorization formalism together with the unintegrated gluon density obtained within the CCFM evolution approach from a fit to HE

M. Soida, M. Urbanik, R. Beck, R. Wielebinski

By observing the interacting galaxy NGC 3627 in radio polarization we try to answer the question to which degree the magnetic field follows the galactic gas flows. We obtained total power and polarized intensity maps at 8.46 GHz and 4.85 GHz using the VLA in its compact D-configuration. In order to overcome the zero-spacing problems, the interferometric data

Joseph Roitberg

If C=C_ϕdenotes the mapping cone of an essential phantom map ϕfrom the suspension of the Eilenberg-Mac Lane complex K=K(Z,5) to the 4-sphere S=S^4 we derive the following properties: (1) The LS category of the product of C with any n-sphere S^n is equal to 3; (2) The LS category of the product of C with itself is equal to 3, hence is strictly less than twice

Huijie Yang, Fangcui Zhao, Yizhong Zhuo, Xizhen Wu

By means of the concept of Factorial Moments we examine DNA sequences from Yeast to distinguish coding and non-coding regions. It is found that the FM may be a powerful tool for analysis of DNA sequences. PACS numbers: 87.15.Cc,87.10.+e,87.14.Gg

Kiyoshi Hayasaka, Ryuichi Nakayama

We point out that when a D-brane is placed in an NS-NS B field background with non-vanishing field strength (H=dB) along the D-brane worldvolume, the coordinate of one end of the open string does not commute with that of the other in the low energy limit. The degrees of the freedom associated with both ends are not decoupled and accordingly, the effective ac

Mauro Sellitto

Boundary-induced transport in particle systems with anomalous diffusion exhibits rectification, negative resistance, and hysteresis phenomena depending on the way the drive acts on the boundary. The solvable case of a 1D system characterized by a power-law diffusion coefficient and coupled to two particles reservoirs at different chemical potential is examin

J. L. Chkareuli

Present situation in the flavour mixing of quarks and leptons is briefly reviewed and a new approach called the Minimal Flavour Mixing (MFM) is considered in detail. According to MFM the whole of the flavour mixing is basically determined by the physical mass generation of the first family of fermions. So, in the chiral symmetry limit when the masses of the

Martin Lemoine, Musongela Lubo, Jerome Martin, Jean-Philippe Uzan

This article presents the derivation of the stress-energy tensor of a free scalar field with a general non-linear dispersion relation in curved spacetime. This dispersion relation is used as a phenomelogical description of the short distance structure of spacetime following the conventional approach of trans-Planckian modes in black hole physics and in cosmo

P. H. Chavanis

We discuss the nature of phase transitions in self-gravitating systems both in the microcanonical and in the canonical ensemble. We avoid the divergence of the gravitational potential at short distances by considering the case of self-gravitating fermions and hard spheres models. Three kinds of phase transitions (of zeroth, first and second order) are eviden

H. Jeong, M. S. Kim

Universal quantum computation using optical coherent states is studied. A teleportation scheme for a coherent-state qubit is developed and applied to gate operations. This scheme is shown to be robust to detection inefficiency.

Robert C. Myers, Oyvind Tafjord

We examine a family of BPS solutions of ten-dimensional type IIb supergravity. These solutions asymptotically approach AdS_5 X S^5 and carry internal `angular' momentum on the five-sphere. While a naked singularity appears at the center of the anti-de Sitter space, we show that it has a natural physical interpretation in terms of a collection of giant gravit

J. Gutowski

We examine domain wall solutions of N=1, D=4 supergravity which preserve half of the supersymmetry and arise from Euclidean M2-brane instantons on M5-branes wrapping associative 3-cycles of G_2 holonomy manifolds. We also investigate composite solutions which break an additional half of the supersymmetry.

H. Arodź, R. Pełka

Using Landau-de Gennes effective theory for nematic liquid crystals we analyse the structure of rectilinear n=1/2 smooth disclination line in the case of equal elastic constants. We find that at certain temperature there is an exact mathematical correspondence with a rectilinear vortex in superfluid $^4He$. With a help of polynomial approximation difference

E. Kanzieper

Correlation function of complex eigenvalues of N by N random matrices drawn from non-Hermitean random matrix ensemble of symplectic symmetry is given in terms of a quaternion determinant. Spectral properties of Gaussian ensembles are studied in detail in the regimes of weak and strong non-Hermiticity.

P. L Ramazza, E. Benkler, S. Boccaletti, U. Bortolozzo

We experimentally demonstrate the broad tunability of the main features of optical localized structures (LS) in a nonlinear interferometer. By discussing how a single LS depends on the system spatial frequency bandwidth, we show that a modification of its tail leads to the possibility of tuning the interactions between LS pairs, and thus the equilibrium dist

Noriyoshi Ishii, Hideo Suganuma, Hideo Matsufuru

We report the first study of the glueball properties at finite temperatures below T_c using SU(3) anisotropic lattice QCD with beta=6.25, the renormalized anisotropy xi \equiv a_s/a_t = 4 and 20^3 \times N_t (N_t=35,36,37,38,40,43,45,50,72) at the quenched level. From the temporal correlation analysis with the smearing method, about 20 % mass reduction is ob

Keun-Young Kim, Bum-Hoon Lee, Hyun Seok Yang

We study U(1) and U(2) noncommutative instantons on R^2_{NC} x R^2_C based on the ADHM construction. It is shown that a mild singularity in the instanton solutions for both self-dual and anti-self-dual gauge fields always disappears in gauge invariant quantities and thus physically regular solutions can be constructed even though any projected states are not

Huijie Yang, Fangcui Zhao, Yizhong Zhuo, Xizhen Wu

By means of Factorial Moments(FM), the long-range correlations embedded in gait time series are investigated. It is found that FM is an effective tool to deal with this kind of time series. Keywords: Factorial Moments,Time series, Long-range correlations

Christopher King, Michael Nathanson, Mary Beth Ruskai

We give examples of qubit channels that require three input states in order to achieve the Holevo capacity.

B. C. Travaglione, G. J. Milburn

Recently, several groups have investigated quantum analogues of random walk algorithms, both on a line and on a circle. It has been found that the quantum versions have markedly different features to the classical versions. Namely, the variance on the line, and the mixing time on the circle increase quadratically faster in the quantum versions as compared to

John Langford

A generic approach for compiling any classical block compression algorithm into a quantum block compression algorithm is presented. Using this technique, compression asymptoticaly approaching the von Neumann entropy of a qubit source can be achieved. The automatically compiled algorithms are competitive (in time and space complexity) with hand constructed qu

Sergio Albeverio, Shao-Ming Fei

The quantum entanglements are studied in terms of the invariants under local unitary transformations. A generalized formula of concurrence for $N$-dimensional quantum systems is presented. This generalized concurrence has potential applications in studying separability and calculating entanglement of formation for high dimensional mixed quantum states.

S. Virmani, M. F. Sacchi, M. B. Plenio, D. Markham

In a recent paper, Walgate et. al. demonstrated that any two orthogonal multipartite pure states can be optimally distinguished using only local operations. We utilise their result to show that this is true for any two multiparty pure states, in the sense of inconclusive discrimination. There are also certain regimes of conclusive discrimination for which th

Petr Kral

We discuss general formation of complementary behaviors, functions and forms in biological species competing for resources. We call orthogonalization the related processes on macro and micro-level of a self-organized formation of correlations in the species properties. Orthogonalization processes could be, for example, easily observed in sympatric speciation

A. V. Korol, A. V. Solov'yov, W. Greiner

We suggest a new type of radiation (acoustically induced radiation - AIR), which is generated by ultrarelativistic particles channeling in crystal along a crystal plane (or axis), which is bent by a transverse acoustic wave. The AIR mechanism allows to make an undulator with characteristics inaccessible in the undulators based on the motion of particles in t

Andrea di Stefano, Marie Fauquembergue, Philippe Verkerk, Daniel Hennequin

The paper reports on the observation of a new type of instabilities in the atomic cloud of a magneto-optical trap (MOT). They appear as large amplitude self-oscillations, either periodic or erratic, depending on the parameters. An original model taking into account the shadow effect and an homogeneous distribution of the atoms in the cloud is developped. It

V. P. Berezovoj, Yu. L. Bolotin, V. Yu. Gonchar, M. Ya. Granovsky

The present communication is a continuation of the review, the first part of which was presented in nucl-th/0109033. The second part dealswith the manifistation of Chaotic dynamics at quantum level. The variations of statistical properties of energy spectrum in the process of R-C-R transition have been studied in detail. We proved that the type of the classi

D. P. Menezes, C. Providencia

In this work we calculate the caloric curve (excitation energy per particle as a function of temperature) for finite nuclei within the non--linear Walecka model for different proton fractions. It is shown that the caloric curve is sensitive to the proton fraction. Freeze-out volume effects in the caloric curve are also studied.

A. A. Isayev

Superfluid states of symmetric nuclear matter with finite total momentum of Cooper pairs (nuclear LOFF phase) are studied with the use of Fermi-liquid theory in the model with Skyrme effective forces. It is considered the case of four-fold splitting of the excitation spectrum due to finite superfluid momentum and coupling of T=0 and T=1 pairing channels. It

Miloslav Znojil

Sextic oscillator in D dimensions is considered as a typical quasi-exactly solvable (QES) model. Usually, its QES N-plets of bound states have to be computed using the coupled Magyari's nonlinear algebraic equations. We propose and describe an alternative linear method which is N-independent and works with power series in 1/\sqrt(D). Main merit: simultan

Maxim Braverman

Let $D$ be a (generalized) Dirac operator on a non-compact complete Riemannian manifold $M$ acted on by a compact Lie group $G$. Let $v:M --> Lie(G)$ be an equivariant map, such that the corresponding vector field on $M$ does not vanish outside of a compact subset. These data define an element of $K$-theory of the transversal cotangent bundle to $M$. Hence a

Faisal Fairag

We consider two-level finite element discretization methods for the stream function formulation of the Navier-Stokes equations. The two-level method consists of solving a small nonlinear system on the coarse mesh, then solving a linear system on the fine mesh. The basic result states that the errors between the coarse and fine meshes are related superlinearl

Jose Luis Arregui

It is shown that Bernoulli numbers and tangent numbers (the derivatives of the tangent function at zero) can be obtained by means of easily defined triangles of numbers in several ways, some of them very similar to the Catalan triangle and a Motzkin-like triangle. Our starting point in order to show this is a new expression of Zeta(2n) involving Motzkin path

A. Chigogidze, A. Karasev, M. Zarichnyi

It is proved that there is no structure of left (right) cancelative semigroup on $[L]$-dimensional universal space for the class of separable compact spaces of extensional dimension $\le [L]$. Besides, we note that the homeomorphism group of $[L]$-dimensional space whose nonempty open sets are universal for the class of separable compact spaces of extensiona

Guy Gielis, Geoffrey Grimmett

We study conditioned random-cluster measures with edge-parameter p and cluster-weighting factor q satisfying q \ge 1. The conditioning corresponds to mixed boundary conditions for a spin model. Interfaces may be defined in the sense of Dobrushin, and these are proved to be `rigid' in the thermodynamic limit, in three dimensions and for sufficiently large

Elcio Abdalla, L. Alejandro Correa-Borbonet

Some thermodynamical properties of Lovelock gravity are discussed in several space-time dimensions, the holographic principle being one of the ingredients of the discussion. As it turns out, the area law and the brickwall method, though correct for the Einstein-Hilbert theory, may fail to work in general.

Thomas Schucker, Sami Zouzou

We rehabilitate the M_1(C)+ M_2(C)+ M_3(C) model of electro-magnetic, weak and strong forces as an almost commutative geometry in the setting of the spectral action.

W. Machin

The most general N=1 Lagrangian for the spinning particle with local supersymmetry is found and the constraints of the system are analysed. The Dirac quantisation of the model is also investigated.

Shoichi Ichinose

A solution of the 6D gravitational model, which has the pole configuration, is found. The vacuum setting is done by the 6D Higgs potential and the solution is for a family of the vacuum and boundary parameters. The boundary condition is solved by the $1/k^2$-expansion (thin pole expansion) where $1/k$ is the {\it thickness} of the pole. The obtained analytic

Andre de Gouvea

I review some aspects concerning the physics of neutrino mixing and oscillations. I discuss in some detail the physical neutrino oscillations parameter space in the case of two and three family mixing, and briefly describe the current knowledge of neutrino mixing parameters according to the present solar, atmospheric, and reactor neutrino data. I also briefl

E. Lunghi, D. Wyler

Complex flavour couplings (off-diagonal mass terms) in the squark sector of supersymmetric theories may drastically alter both the rate and the CP-violating asymmetry of certain B-meson decays. We consider the effects of couplings that induce b -> s transitions and lead to final state with strangeness one. We investigate the bounds that must be satisfied by

V. Del Duca, W. Kilgore, C. Oleari, C. R. Schmidt

In this talk we present a calculation of Higgs production via gluon fusion in association with two jets, including the full top-quark mass dependence, and compare it to the large top-mass limit. We find that the large top-mass limit is a good approximation as long as the Higgs mass is smaller than the top quark pair mass, and the jet transverse energies are

B. Jaeger, W. Schweiger

We investigate the reaction gamma+p -> V+p, with V denoting a Phi or a J/Psi meson, within the scope of perturbative QCD, treating the proton as a quark-diquark system. Our predictions extrapolate the existing forward differential cross-section data into the few-GeV momentum-transfer region. In case of the J/Psi reasonable results are only obtained by proper

M. Schwaerz, W. Schweiger

The, so called, "hard-scattering approach" represents a suitable framework for the perturbative treatment of exclusive hadronic processes at large energies and (transverse) momentum transfers. In this context, diquarks can serve as a useful phenomenological concept to model non-perturbative effects which are still observable in the kinematic range ac

M. Slusarczyk, A. Wereszczynski

We discuss a model with a massless scalar coupling to the Yang-Mills SU(2) gauge field in four-dimensional space-time. The solutions from static, pointlike colour source are given. There exists not only solutions with finite energy but also singular one which describes confinement. The confining potential depends on the $δ$ parameter of our model. The regula

A. K. Chaudhuri

We have analyzed the latest NA50 data on $J/ψ$ suppression in Pb + Pb collisions. $J/ψ$ production is assumed to be a two step process, (i) formation of $c\bar{c}$ pair, which is accurately calculable in QCD and (ii) formation of $J/ψ$ meson from the $c\bar{c}$ pair, which can be conveniently parameterized. In a pA/AA collision, the as the $c\bar{c}$ pair pa

E. Gilboa

An interaction term is added to the QCD Lagrangian involving hadron and gluon fields. An effective vertex is calculated for such interactions through exchanges of reggeized gluons. This gives rise to an effective coupling for hadron-gluon elastic scattering in the t-channel, which is used in an inclusive hadron-hadron interaction from which the Pomeron inter

Guy D. Moore

I show how interaction corrections to the Bose condensation temperature of an atomic gas can be computed using a combination of perturbative effective field theory and lattice techniques.

The CDF Collaboration, T. Affolder

We report a measurement of the diffractive structure function $F_{jj}^D$ of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in $\bar pp$ collisions at $\sqrt s=630$ GeV at the Fermilab Tevatron. The ratio of $F_{jj}^D$ at $\sqrt s=630$ GeV to $F_{jj}^D$ obtained from a similar measurement at $\sqrt s=180

Konstantin Goulianos

Results on soft and hard diffraction obtained by the CDF Collaboration in Run I of the Fermilab Tevatron pbar-p collider are reviewed and compared with results from the DESY e-p collider HERA and with theoretical expectations. In addition, the CDF program for diffractive studies in Run II is briefly reviewed with emphasis on the relevant detector upgrades an

Stefan Soldner-Rembold

The measurements of the leptonic branching ratios BR(Ds->tau nu) and BR(Ds->mu nu) are reviewed. The values of the Ds decay constant fDs derived from the measurements are updated and a world average is calculated taking into account the large correlations between the measurements

The FOCUS Collaboration

A high statistics sample of photo-produced charm from the FOCUS(E831) experiment at Fermilab has been used to search for direct CP violation in the decays D+->K_S pi+ and D+ -> K_S K+. We have measured the following asymmetry parameters relative to D+->K-pi+pi+: A_CP(K_S pi+) = (-1.6 +/- 1.5 +/- 0.9)%, A_CP(K_S K+) = (+6.9 +/- 6.0 +/- 1.5)% and A_CP(K_S K+)

A. Corichi, G. Cruz, A. Minzoni, P. Padilla

The full quantum mechanical collapse of a small relativistic dust shell is studied analytically, asymptotically and numerically starting from the exact finite dimensional classical reduced Hamiltonian recently derived by Háj{\'ı}ček and Kuchař. The formulation of the quantum mechanics encounters two problems. The first is the multivalued nature of the Ha

Seth A. Major, Michael D. Seifert

Within the context of loop quantum gravity there are several operators which measure geometry quantities. This work examines two of these operators, volume and angle, to study quantum geometry at a single spin network vertex - ``an atom of geometry.'' Several aspects of the angle operator are examined in detail including minimum angles, level spacing

Dhurjati Prasad Datta

We investigate the question, "how does time flow?" and show that time may change by inversions as well. We discuss its implications to a simple class of linear systems. Instead of introducing any unphysical behaviour, inversions can lead to a new multi- time scale evolutionary path for the linear system exhibiting late time stochastic fluctuations. W

Kostas D. Kokkotas, Nils Andersson

In this short review we discuss the relevance of ongoing research into stellar oscillations and associated instabilities for the detection of gravitational waves and the future field of ``gravitational-wave astronomy''.

Emmanuel Beffara, Olivier Bournez, Hassen Kacem, Claude Kirchner

ELAN is a powerful language and environment for specifying and prototyping deduction systems in a language based on rewrite rules controlled by strategies. Timed automata is a class of continuous real-time models of reactive systems for which efficient model-checking algorithms have been devised. In this paper, we show that these algorithms can very easily b

Jordi Atserias, Lluis Padro, German Rigau

This work explores a new robust approach for Semantic Parsing of unrestricted texts. Our approach considers Semantic Parsing as a Consistent Labelling Problem (CLP), allowing the integration of several knowledge types (syntactic and semantic) obtained from different sources (linguistic and statistic). The current implementation obtains 95% accuracy in model

Tomas Muller, Roman Bartak

Timetabling is a typical application of constraint programming whose task is to allocate activities to slots in available resources respecting various constraints like precedence and capacity. In this paper we present a basic concept, a constraint model, and the solving algorithms for interactive timetabling. Interactive timetabling combines automated timeta

Milton L. Mueller

The Internet Domain Name System (DNS) is a hierarchical name space that enables the assignment of unique, mnemonic identifiers to Internet hosts and the consistent mapping of these names to IP addresses. The root of the domain name system is the top of the hierarchy and is currently managed by a quasi-private centralized regulatory authority, the Internet Co

Tom Kennedy

The pivot algorithm is a Markov Chain Monte Carlo algorithm for simulating the self-avoiding walk. At each iteration a pivot which produces a global change in the walk is proposed. If the resulting walk is self-avoiding, the new walk is accepted; otherwise, it is rejected. Past implementations of the algorithm required a time O(N) per accepted pivot, where N

S. Jung, B. Watkins, L. Delong, J. B. Ketterson

We report measurements of the ferromagnetic resonance (FMR) spectra of arrays of submicron size periodic particle arrays of permalloy produced by electron-beam lithography. In contrast to plane ferromagnetic films, the spectra of the arrays show a number of additional resonance peaks, whose position depends strongly on the orientation of the external magneti

J. M. Pruneda, S. K. Estreicher, J. Junquera, J. Ferrer

We have developed a formulation of density functional perturbation theory for the calculation of vibrational frequencies in molecules and solids, which uses numerical atomic orbitals as a basis set for the electronic states. The (harmonic) dynamical matrix is extracted directly from the first order change in the density matrix with respect to infinitesimal a

J. Miller, C. Zeng, N. S. Wingreen, C. Tang

Despite the variety of protein sizes, shapes, and backbone configurations found in nature, the design of novel protein folds remains an open problem. Within simple lattice models it has been shown that all structures are not equally suitable for design. Rather, certain structures are distinguished by unusually high designability: the number of amino-acid seq

I. schnell, G. Czycholl, R. C. Albers

We present first-principles calculations of optimally localized Wannier functions for Cu and use these for an ab-initio determination of Hubbard (Coulomb) matrix elements. We use a standard linearized muffin-tin orbital calculation in the atomic-sphere approximation (LMTO-ASA) to calculate Bloch functions, and from these determine maximally localized Wannier

H. W. Zandbergen, M. Y. Wu, H. Jiang, M. A. Hayward

Electron diffraction and high resolution microscopy have been performed on Mg1-xAlxB2 with x~0.5. This composition displays a superstructure with a repeat period of exactly 2c along the c axis and about 10 nm in the a-b plane. The superstructure results in ring-shaped superreflections in the diffraction pattern. Irradiation by a strong electron beam results

O. V. Dolgov, M. L. Kulic

The dynamical conductivity $σ(ω)$, reflectivity $R(ω)$, and tunneling density of states $N(ω)$ of strongly correlated systems (like heavy fermions) with a spin-density wave (SDW) magnetic order are studied as a function of impurity scattering rate and temperature. The theory is generalized to include strong coupling effects in the SDW order. The results are

A. Anthore, F. Pierre, H. Pothier, D. Esteve

We have measured in a copper wire the energy exchange rate between quasiparticles as a function of the applied magnetic field. We find that the effective electron-electron interaction is strongly modified by the magnetic field, suggesting that magnetic impurities play a role on the interaction processes.

J. W. Clark, V. A. Khodel, M. V. Zverev

It is demonstrated the Fermi surface of dense neutron matter may experience a rearrangement near the onset of pion condensation, due to strong momentum dependence of the effective interaction induced by spin-isospin fluctuations. In particular, the Fermi surface may take the form of a partially hollow sphere having a spherical hole in its center (a ``Lifschi

N. Pavlenko, J. W. Evans, Da-Jiang Liu, R. Imbihl

We present lattice-gas modeling of the steady-state behavior in CO oxidation on the facets of nanoscale metal clusters, with coupling via inter-facet CO diffusion. The model incorporates the key aspects of reaction process, such as rapid CO mobility within each facet, and strong nearest-neighbor repulsion between adsorbed O. The former justifies our use a &#

P. Zahn, N. Papanikolaou, F. Erler, I. Mertig

We present ab-initio calculations for the in plane conductivity of Co/Cu multilayer slabs. The electronic structure of the multilayer slabs is calculated by means of density functional theory within a screened KKR scheme. Transport properties are described using the Boltzmann equation in relaxation time approximation. We study the change of the conductivity

Peter Sollich

Many materials containing colloids or polymers are polydisperse: They comprise particles with properties (such as particle diameter, charge, or polymer chain length) that depend continuously on one or several parameters. This review focusses on the theoretical prediction of phase equilibria in polydisperse systems; the presence of an effectively infinite num

A. A. Rovenchak, I. O. Vakarchuk

We adduce the results of the condensate fraction calculation for liquid helium-4. The method is derived from the first principles and involves minimum assumptions. The only experimental quantity we need in our calculations is the static structure factor which is easily measurable. We use the approximation in which expressions contain one summation in the wav

V. Zlatic, J. K. Freericks

The exact solution of the multi-component Falicov-Kimball model in infinite-dimensions is presented and used to discuss a new fixed point of valence fluctuating intermetallics with Yb and Eu ions. In these compounds, temperature, external magnetic field, pressure, or chemical pressure induce a transition between a metallic state with the f-ions in a mixed-va

A. Latz, M. Letz, R. Schilling, Th. Theenhaus

To investigate the influence of orientational degrees of freedom onto the dynamics of molecular systems in its supercooled and glassy regime we have solved numerically the mode-coupling equations for hard ellipsoids of revolution. For a wide range of volume fractions $ϕ$ and aspect ratios $x_{0}$ we find an orientational peak in the center of mass spectra $χ

Walter Kob, Markus Nauroth, Francesco Sciortino

We calculate for a binary mixture of Lennard-Jones particles the time dependence of the solution of the mode-coupling equations in which the full wave vector dependence is taken into account. In addition we also take into account the short time dynamics, which we model with a simple memory kernel. We find that the so obtained solution agrees very well with t

J. Horvat, X. L. Wang, S. Soltanian, S. X. Dou

Transport critical current (Ic) was measured for Fe-sheathed MgB2 round wires. A critical current density of 5.3 x 10^4 A/cm^2 was obtained at 32K. Strong magnetic shielding by the iron sheath was observed, resulting in a decrease in Ic by only 15% in a field of 0.6T at 32K. In addition to shielding, interaction between the iron sheath and the superconductor

Maxim Mostovoy, Frank Antonsen, Jasper Knoester

We apply the optimal fluctuation method to the calculation of the optical absorption in disordered one-dimensional semiconductors below the fundamental optical gap. We find that a photon energy exists at which the shape of the optimal fluctuation undergoes a dramatic change, resulting in a different energy dependence of the absorption rate above and below th

Ugur Tirnakli

We numerically study, at the edge of chaos, the behaviour of the sibgle-site map $x_{t+1}=x_t-x_t/(x_t^2+γ^2)$, where $γ$ is the map parameter.

Piotr Flin, Janusz Krywult

Frequencies of substructure within Abell clusters determined for the same objects using the wavelet analysis for 2-D and 3-D data are similar.

Ray Jayawardhana, Alexis Brandeker

Young stellar systems in the solar neighborhood provide valuable laboratories for detailed studies of star and planet formation. The bright F8V star HD 199143 and the Li-rich late-type emission line star HD 358623 are among the nearest young stars identified to date, and may be members of a young association in Capricornus. We present high-resolution near-in

A. Aguirre, J. Schaye, L. Hernquist, D. Weinberg

This paper discusses a semi-numerical method of investigating the enrichment of the intergalactic medium by galactic winds. We find that most galaxies at z >~ 3 should be driving winds, and that (if these winds are similar to those at low-z) these winds should escape to large distances. Our calculations -- which permit exploration of a large region of model

Steven V. Penton, John T. Stocke, J. Michael Shull

In this paper, we use large-angle, nearby galaxy redshift surveys to investigate the relationship between the 81 low-redshift Lya absorbers in our HST/GHRS survey and galaxies, superclusters, and voids. In a subsample of 46 Lya absorbers located in regions where the February 8, 2000 CfA catalog is complete down to at least L* galaxies, the nearest galaxy nei

T. Fang, G. L. Bryan

Recent STIS and FUSE observations have detected OVI absorption lines at low redshift that are not clearly associated with any galactic system. In this paper, we argue that these lines are due to metal enriched hot gas in the intergalactic medium. Using numerical simulations of a cosmological-constant dominated cosmology, combined with reasonable assumptions

Daniel Egret, Francoise Genova

Interoperability is one of the key issues in the current efforts to build the Virtual Observatory. We present here some of the tools which already contribute to the efficient exchange of information between archives, databases, and journals.

Ruth Durrer

The physics of the origin and evolution of CMB anisotropies is described. I explain the idea and status of cosmic parameter estimation and follow it up with critical comments on its dependence on model assumptions and initial conditions.

L. R. Abramo, R. P. Woodard

We demonstrate the existence of a secular back-reaction on inflation using a simple scalar model. The model consists of a massless, minimally coupled scalar with a quartic self-interaction which is a spectator to $Λ$-driven inflation. To avoid problems with coincident propagators, and to make the scalars interact more like gravitons, we impose a covariant no

L. R. Abramo, R. P. Woodard

We use an invariant operator to study the quantum gravitational back-reaction to scalar perturbations during chaotic inflation. Our operator is the inverse covariant d'Alembertian expressed as a function of the local value of the inflaton. In the slow roll approximation this observable gives $-1/(2 H^2)$ for an arbitrary homogeneous and isotropic geometr

L. R. Abramo, R. P. Woodard

We define a scalar measure of the local expansion rate based on how astronomers determine the Hubble constant. Our observable is the inverse conformal d'Alembertian acting on a unit ``standard candle.'' Because this quantity is an integral over the past lightcone of the observation point it provides a manifestly causal and covariant technique for

Martin Still, Koji Mukai

The XMM-Newton pointing towards the magnetic cataclysmic variable UZ For finds the source to be a factor > 10^3 fainter than previous EXOSAT and ROSAT observations. The source was not detected for the majority of a 22 ksec exposure with the EPIC cameras, suggesting that the accretion rate either decreased, or stopped altogether. However a 1.1 ksec burst was

M. Revnivtsev, R. Sunyaev, M. Gilfanov, E. Churazov

An optical spectroscopy of an unusual fast transient V4641 Sgr constrains its mass to 8.7-11.7M_sun (9.6M_sun is the best fit value) and the distance to 7.4--12.3 kpc (Orosz et al. 2001). At this distance the peak flux of 12 Crab in the 2--12 keV energy band, measured by ASM/RXTE, implies the X-ray luminosity exceeding 2-3e39 erg/s, i.e. near or above the Ed

M. Audard, M. Guedel, A. Sres, R. Mewe

XMM-Newton has been performing comprehensive studies of X-ray bright RS CVn binaries in its Calibration and Guaranteed Time programs. We present results from ongoing investigations in the context of a systematic study of coronal emission from RS CVns. We concentrate in this paper on coronal abundances and investigate the abundance pattern in RS CVn binaries

M. Guedel, M. Audard, K. W. Smith, A. Sres

We have been conducting a comprehensive survey of stellar coronae with the XMM-Newton Reflection Grating Spectrometers during the commissioning, calibration, verification, and guaranteed time phases of the mission, accompanied by simultaneous observations with the EPIC cameras and, for several targets, with the radio VLA and/or the VLBA. The principal aim of

Manuel Guedel

Coronae express different facets of their energy release processes in different wavelength regions. While soft X-ray and EUV emission dominates the radiative losses of the thermal plasma, hard X-ray emission (>10 keV) can be produced from non-thermal high-energy particles accelerated as a consequence of flare processes, and radio emission is often emitted fr

M. Audard, M. Guedel, A. Sres, R. Mewe

XMM-Newton has been performing comprehensive studies of X-ray luminous RS CVn binary systems in its calibration and guaranteed time programs. We present results from ongoing investigations in the context of a systematic study of coronal emission from RS CVns. We concentrate here on coronal abundances and investigate the abundance pattern in RS CVn binaries a

M. E. Machacek, M. W. Bautz, C. R. Canizares, G. P. Garmire

We present results from two observations (combined exposure of ~17 ks) of galaxy cluster A2218 using the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory that were taken on October 19, 1999. Using a Raymond-Smith single temperature plasma model corrected for galactic absorption we find a mean cluster temperature of kT = 6.9+/-0.5 keV,

W. E. Schaap, R. van de Weygaert

Optimally resolved one-dimensional density and velocity profiles through cosmological N-body simulations are constructed by means of the Voronoi-Delaunay tessellation reconstruction technique. In a fully self-adaptive fashion a strikingly detailed view of the density features and the corresponding cosmic motions is recovered.

D. Clowe, P. Schneider

We present the weak lensing mass reconstructions of three clusters of galaxies from data taken on the ESO Wide Field Imager. We detect a lensing signal in all three clusters over a range of 1&#39; < r < 17&#39; (~0.1 h^-1 Mpc < r < 2 h^-1 Mpc). We measure the best fitting SIS and NFW profiles for each cluster and show that in two of the three clusters the NF