June 2007 arXiv papers — page 10

Oscar Iglesias, Amilcar Labarta, Xavier Batlle

We present an atomistic model of a single nanoparticle with core/shell structure that takes into account its lattice strucutre and spherical geometry, and in which the values of microscopic parameters such as anisotropy and exchange constants can be tuned in the core, shell and interfacial regions. By means of Monte Carlo simulations of the hysteresis loops

Jinn-Ouk Gong

We explore a new possibility that some inflaton fields in multi-field inflation models satisfy the observed value of the spectral index so that the curvature perturbation generated by them through post-inflationary dynamics may be relevant for the current observations. We illustrate this point using a simple and reasonable multi-field chaotic inflation model

Masaki Satoh, Sugumi Kanno, Jiro Soda

We study a mechanism to produce the circular polarization of primordial gravitational waves. The circular polarization is generated during the super-inflation driven by the Gauss-Bonnet term in the string-inspired cosmology. The instability in the tensor mode caused by the Gauss-Bonnet term and the parity violation due to the gravitational Chern-Simons term

Thierry Champel, Tomas Löfwander, Matthias Eschrig

We study the pi phase in a superconductor-ferromagnet-superconductor Josephson junction, with a ferromagnet showing a cycloidal spiral spin modulation with in-plane propagation vector. Our results reveal a high sensitivity of the junction to the spiral order and indicate the presence of 0-pi quantum phase transitions as function of the spiral wave vector. We

R. Lortz, Y. Wang, A. Demuer, P. H. M. Böttger

The specific heat of the layered organic superconductor $κ$-% (BEDT-TTF)$_2$Cu(NCS)$_2$, where BEDT-TTF is bisethylenedithio-% tetrathiafulvalene, has been studied in magnetic fields up to 28 T applied perpendicular and parallel to the superconducting layers. In parallel fields above 21 T, the superconducting transition becomes first order, which signals tha

Mikhail S. Kalenkov, Andrei D. Zaikin

With the aid of the quasiclassical Eilenberger formalism we develop a theory of non-local electron transport across three-terminal ballistic normal-superconducting-normal (NSN) devices with spin-active NS interfaces. The phenomenon of crossed Andreev reflection (CAR) is known to play the key role in such transport. We demonstrate that CAR is highly sensitive

Avrim Blum, Amin Coja-Oghlan, Alan Frieze, Shuheng Zhou

In this paper, we consider the problem of partitioning a small data sample drawn from a mixture of $k$ product distributions. We are interested in the case that individual features are of low average quality $γ$, and we want to use as few of them as possible to correctly partition the sample. We analyze a spectral technique that is able to approximately opti

Ivan P. Christov

We examine the relation between the recently proposed time-dependent quantum Monte Carlo (TDQMC) method and the principles of stochastic quantization. In both TDQMC and stochastic quantization particle motion obeys stochastic guidance equations to preserve quantum equilibrium. In this way the probability density of the Monte Carlo particles corresponds to th

H. Arenhoevel

The influence of Coulomb distortion on the polarization transfer in elastic proton and antiproton electron scattering at low energies is calculated in a distorted wave Born approximation. For antiproton electron scattering Coulomb effects reduce substantially the spin transfer cross section compared to the plane wave Born approximation whereas for proton ele

M. Yoshida, N. Ogata, M. Takigawa, J. Yamaura

We report magnetization, nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and transmission electron microscopy (TEM) studies on the quasi-two-dimensional spin-gap system (CuCl)LaNb2O7, a possible candidate for the J1-J2 model on a square lattice. A sharp single NQR line is observed at the Cu and Cl sites, indicating that both Cu and Cl a

Tosiaki Kori

We introduce a pre-symplectic structure on the space of connections in a G-principal bundle over a four-manifold and a Hamiltonian action on it of the group of gauge transformations that are trivial on the boundary. The moment map is given by the square of curvature so that the 0-level set is the space of flat connections. Thus the moduli space of flat conne

Zakaria Giunashvili

We give an algebraic construction of connection on the symplectic leaves of Poisson manifold, introduced in \cite{Ginzburg}. This construction is suitable for the definition of the linearized holonomy on a regular symplectic foliation.

Claude Sabbah

We give an explicit formula (i.e., a formal stationary phase formula) for the local Fourier-Laplace transform of a formal germ of meromorphic connection of one complex variable with a possibly irregular singularity. This is a complex analogue of the formulas in the preprint math/0702436v1.

Anatoly D. Plotnikov

We develop an experimental algorithm for the exact solving of the maximum independent set problem. The algorithm consecutively finds the maximal independent sets of vertices in an arbitrary undirected graph such that the next such set contains more elements than the preceding one. For this purpose, we use a technique, developed by Ford and Fulkerson for the

Wontae Kim, Hyeonjoon Shin

The Hawking radiation from the three dimensional rotating acoustic black hole is considered from the viewpoint of anomaly cancellation method initiated by Robinson and Wilczek. Quantum field near the horizon is effectively described by two dimensional charged field with a charge identified as the angular momentum m. The fluxes of charge and energy are obtain

E. Muller, K. Bekki

We investigate the formation of a number of key large-scale HI features in the ISM of the Magellanic Bridge using dissipationless numerical simulation techniques. This study comprises the first direct comparison between detailed HI maps of the Bridge and numerical simulations. We confirm that the SMC forms two tidal filaments: a near arm, which forms the con

Sourav Chatterjee, Soumik Pal

Consider a time-varying collection of n points on the positive real axis, modeled as exponentials of n Brownian motions whose drift vector at every time point is determined by the relative ranks of the coordinate processes at that time. If at each time point we divide the points by their sum, under suitable assumptions the rescaled point process converges to

Wei-Qiang Chen, Kai-Yu Yang, T. M. Rice, F. C. Zhang

Magnetic field induced antiferromagnetic phase of the underdoped cuprates is studied within the t-t'-J model. A magnetic field suppresses the pairing amplitude, which in turn may induce antiferromagnetism. We apply our theory to interpret the recently reported quantum oscillations in high magnetic field in ortho-II YBa2Cu3O6.5 and propose that the total

A. Klypin, F. Prada

The motion of satellite galaxies around normal galaxies at distances 50-500 kpc provides a sensitive test for the theories. We study the surface density and the velocities of satellites around isolated galaxies in the Sloan Digital Sky Survey. We find that the surface number-density of satellites declines with the projected distance as a power law with the s

Xiaobo Liu, Chuu-Lian Terng

A submanifold in space forms is isoparametric if the normal bundle is flat and principal curvatures along any parallel normal fields are constant. We study the mean curvature flow with initial data an isoparametric submanifold in Euclidean space and sphere. We show that the mean curvature flow preserves the isoparametric condition, develops singularities in

Shinji Ejiri

We propose a method to probe the nature of phase transitions in lattice QCD at finite temperature and density, which is based on the investigation of an effective potential as a function of the average plaquette. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass $m/T = 0.4$, and find that a fir

S. J. O'Toole, C. G. Tinney, H. R. A. Jones

We present a quantitative investigation of the effect of stellar oscillations on Doppler velocity planet searches. Using data from four asteroseismological observation campaigns, we find a power law relationship between the noise impact of these oscillations on Doppler velocities and both the luminosity-to-mass of the target stars, and observed integration t

Samer Al Kiswany, Matei Ripeanu, Sudharshan S. Vazhkudai, Abdullah Gharaibeh

Checkpointing is an indispensable technique to provide fault tolerance for long-running high-throughput applications like those running on desktop grids. This paper argues that a dedicated checkpoint storage system, optimized to operate in these environments, can offer multiple benefits: reduce the load on a traditional file system, offer high-performance th

Xian-Hui Zhong, Qiang Zhao, Jun He, Bijan Saghai

A chiral quark model approach is extended to the study of the $πN$ scattering at low energies. The process of $π^{-}p \to ηn$ near threshold is investigated. The model is successful in describing the differential cross sections and total cross section near the $η$ production threshold. The roles of the resonances in $n\leq 2$ shells are clarified. Near thres

Yasuhiro Asano, Yuki Sawa, Yukio Tanaka, Alexander A. Golubov

We study Josephson current in superconductor / diffusive ferromagnet /superconductor junctions by using the recursive Green function method. When the exchange potential in a ferromagnet is sufficiently large as compared to the pair potential in a superconductor, an ensemble average of Josephson current is much smaller than its mesoscopic fluctuations. The Jo

Ming-Shyang Chang, Ian Affleck

Density Matrix Renormalization Group (DMRG) calculations on 4-leg t-J and Hubbard ladders have found a phase exhibiting "stripes" at intermediate doping. Such behavior can be viewed as generalized Friedel oscillations, with wavelength equal to the inverse hole density, induced by the open boundary conditions. So far, this phase has not been understoo

Sidney van den Bergh

Careful inspection of large-scale photographs of Shapley-Ames galaxies seems to show a smooth transition between the morphological characteristics of galaxies located on the narrow red, and on the broad blue, sequences in the galaxian color-magnitude diagram. In other words there does not appear to be a dichotomy between blue and red galaxies. Both the color

Rory Barnes, Richard Greenberg

The relationship between the boundaries for Hill and Lagrange stability in orbital element space is modified in the case of resonantly interacting planets. Hill stability requires the ordering of the planets to remain constant while Lagrange stability also requires all planets to remain bound to the central star. The Hill stability boundary is defined analyt

J. Hansen

Recent analyses indicate that the amount of atmospheric CO2 required to cause dangerous climate change is at most 450 ppm, and likely less than that. Reductions of non-CO2 climate forcings can provide only moderate, albeit important, adjustments to the CO2 limit. Realization of how close the planet is to "tipping points" with unacceptable consequence

I. P. Ivanov, S. Pacetti

The idea of the vector dominance is still in use in various analyses of experimental data of photon-hadron reactions. It makes sense, therefore, to recast results of microscopic calculations of such reactions in this language. Here we present the diffractive DIS $ρ_3$ production as a specific correction to the generalized vector dominance. We perform a coupl

L. Golinskii, S. Kupin

We obtain various versions of classical Lieb--Thirring bounds for one- and multi-dimensional complex Jacobi matrices. Our method is based on Fan-Mirski Lemma and seems to be fairly general.

Qing Xu, Ashish V. Orpe, Arshad Kudrolli

We investigate the dynamics of a partially saturated grain-liquid mixture with a rotating drum apparatus. The drum is partially filled with the mixture and then rotated about its horizontal axis. We focus on the continous avalanching regime and measure the impact of volume fraction and viscosity of the liquid on the dynamic surface angle. The inclination ang

J. Kubat, D. Korcakova, A. Kawka, A. Pigulski

We verify the nature of emission-line stars in the field of the open cluster NGC 6910. % Spectroscopy in the H-alpha region was obtained. Raw CCD frames of spectra of all stars fainter than V = 9 mag observed by us are significantly affected by nebular emission originating in the surrounding HII region IC 1318. After careful data reduction and subtraction of

Steven G. Krantz, Marco M. Peloso

This paper provides a precise asymptotic expansion for the Bergman kernel on the non-smooth worm domains of Christer Kiselman in complex 2-space. Applications are given to the failure of Condition R, to deviant boundary behavior of the kernel, and to L^p mapping properties of the kernel.

Pierre Billoir, Antoine Letessier-Selvon

The arrival time distribution of cosmic ray events is well suited to extract information regarding sky anisotropies. For an experiment with nearly constant exposure, the frequency resolution one can achieve is given by the inverse of the time $T$ during which the data was recorded. For $T$ larger than one calendar year the resolution becomes sufficient to re

Mark R. Krumholz

The similarity between the mass and spatial distributions of pre-stellar gas cores in star-forming clouds and young stars in clusters provides strong circumstantial evidence that these gas cores are the direct progenitors of individual stars. Here I describe a physical model for the evolution of massive cores into stars, starting with the initial phases of c

F. Dell'Anno, S. De Siena, L. Albano Farias, F. Illuminati

We investigate continuous variable quantum teleportation using non-Gaussian states of the radiation field as entangled resources. We compare the performance of different classes of degaussified resources, including two-mode photon-added and two-mode photon-subtracted squeezed states. We then introduce a class of two-mode squeezed Bell-like states with one-pa

A. N. Timokhin, D. Eichler, Yu. Lyubarsky

A model is presented for the quasiperiodic component of magnetar emission during the tail phase of giant flares. The model invokes modulation of the particle number density in the magnetosphere. The magnetospheric currents are modulated by torsional motion of the surface and we calculate that the amplitude of neutron star surface oscillation should be ~1% of

J. Avloni, L. Florio, A. R. Henn, A. Sparavigna

Polypyrrole chemically synthesized on PET gives rise to textiles with a high electric conductivity, suitable for several applications from antistatics to electromagnetic interference shielding devices. Here, we discuss investigations on thermal electric performances of the polypyrrole coated PET in a wide range of temperatures above room temperature. The See

L. Favart

The Very Forward Proton Spectrometer (VFPS) of the H1 experiment at HERA is collecting data since 2005. The fiber detectors in the Roman pots located at 218 and 222m downstream from the H1 interaction point, tag and measure diffractively scattered protons with a high acceptance in the $\xpom$ range [0.01, 0.025]. The experimental set up and the spectrometer

Elijah Flenner, Francoise Marga, Adrian Neagu, Ioan Kosztin

A distinguishing feature of a multicellular living system is that it operates at various scales, from the intracellular to organismal. Very little is known at present on how tissue level properties are related to cell and subcellular properties. Modern measurement techniques provide quantitative results at both the intracellular and tissue level, but not on

Pierre-Philippe Cortet, Stéphane Santucci, Loic Vanel, Sergio Ciliberto

We study experimentally the slow growth of a single crack in polycarbonate films submitted to uniaxial and constant imposed stress. The specificity of fracture in polycarbonate films is the appearance of flame shaped macroscopic process zones at the tips of the crack. Supported by an experimental study of the mechanical properties of polycarbonate films, an

Albert C. Fannjiang

Two-frequency radiative transfer (2f-RT) theory is developed for geometrical optics in random media. The space-frequency correlation is described by the two-frequency Wigner distribution (2f-WD) which satisfies a closed form equation, the two-frequency Wigner-Moyal equation. In the RT regime it is proved rigorously that 2f-WD satisfies a Fokker-Planck-like e

Ali H. Chamseddine, Alain Connes

The Standard Model is based on the gauge invariance principle with gauge group U(1)xSU(2)xSU(3) and suitable representations for fermions and bosons, which are begging for a conceptual understanding. We propose a purely gravitational explanation: space-time has a fine structure given as a product of a four dimensional continuum by a finite noncommutative geo

Yu Jia

The exclusive decay of $Υ$ to a vector plus pseudoscalar charmonium is studied in perturbative QCD. The corresponding branching ratios are predicted to be of order $10^{-6}$ for first three $Υ$ resonances, and we expect these decay modes should be discovered in the prospective high-luminosity $e^+e^-$ facilities such as super $B$ experiment. As a manifestati

Pete Donnell, Murad Banaji, Stephen Baigent

In this paper, we use a variety of mathematical techniques to explore existence, local stability, and global stability of equilibria in abstract models of mitochondrial metabolism. The class of models constructed is defined by the biological description of the system, with minimal mathematical assumptions. The key features are an electron transport chain cou

Andrej Prsa, Tomaz Zwitter

One of the most important changes in observational astronomy of the 21st Century is a rapid shift from classical object-by-object observations to extensive automatic surveys. As CCD detectors are getting better and their prices are getting lower, more and more small and medium-size observatories are refocusing their attention to detection of stellar variabil

Marcin Molski

Comment on "Classification Scheme for Phenomenological Universalities in Growth Problems in Physics and Other Sciences" by P. Castorina, P. P. Delsanto and C. Guiot, Phys. Rev. Lett. {\bf 96}, 188701 (2006) is presented. It has been proved that the West-like function of growth derived by the authors is incorrect and the approach does not take into ac

Gad Naot

We explore the complex associated to a link in the geometric formalism of Khovanov's (n=2) link homology theory, determine its exact underlying algebraic structure and find its precise universality properties for link homology functors. We present new methods of extracting all known link homology theories directly from this universal complex, and determi

Yann Guermeur

Bounds on the risk play a crucial role in statistical learning theory. They usually involve as capacity measure of the model studied the VC dimension or one of its extensions. In classification, such "VC dimensions" exist for models taking values in {0, 1}, {1,..., Q} and R. We introduce the generalizations appropriate for the missing case, the one o

Cyrille Norotte, Francoise Marga, Adrian Neagu, Ioan Kosztin

The notion of tissue surface tension has provided a physical understanding of morphogenetic phenomena such as tissue spreading or cell sorting. The measurement of tissue surface tension so far relied on strong approximations on the geometric profile of a spherical droplet compressed between parallel plates. We solved the Laplace equation for this geometry an

Marcin Molski, Jerzy Konarski

Comment on the Waliszewski's article "A principle of fractal-sto-chastic dualism and Gompertzian dynamics of growth and self-organization" (BioSystems 82 (2005)61-73) is presented. It has been proved that the main idea of this work that Gompertzian dynamics is governed by the Schrödinger-like equation including anharmonic Morse potential has been

Kuo-An Wu, Alain Karma

We investigate the equilibrium properties of bcc-liquid interfaces modeled with a continuum phase-field crystal (PFC) approach [K. R. Elder and M. Grant, Phys. Rev. E 70, 051605 (2004)]. A multiscale analysis of the PFC model is carried out which exploits the fact that the amplitudes of crystal density waves decay slowly into the liquid in the physically rel

T. Berstermann, T. Auer, H. Kurtze, M. Schwab

The ground state carrier dynamics in self-assembled (In,Ga)As/GaAs quantum dots has been studied using time-resolved photoluminescence and transmission. By varying the dot design with respect to confinement and doping, the dynamics is shown to follow in general a non-exponential decay. Only for specific conditions in regard to optical excitation and carrier

Kirill M. Semenov-Tian-Shansky, Alexander V. Vereshagin, Vladimir V. Vereshagin

This is the 6th paper in the series developing the formalism to manage the effective scattering theory of strong interactions. Relying on the theoretical scheme suggested in our previous publications we concentrate here on the practical aspect and apply our technique to the elastic pion-nucleon scattering amplitude. We test numerically the pion-nucleon spect

R. D. Benguria, M. C. Depassier, M. Loss

We establish rigorous upper and lower bounds for the speed of pulled fronts with a cutoff. We show that the Brunet-Derrida formula corresponds to the leading order expansion in the cut-off parameter of both the upper and lower bounds. For sufficiently large cut-off parameter the Brunet-Derrida formula lies outside the allowed band determined from the bounds.

Richard Hill

We study low order terms of Emerton's spectral sequence for simply connected, simple groups. As a result, for real rank 1 groups, we show that Emerton's method for constructing eigenvarieties is successful in cohomological dimension 1. For real rank 2 groups, we show that a slight modification of Emerton's method allows one to construct eigenvari

Andras Vasy

In this paper we obtain the asymptotic behavior of solutions of the Klein-Gordon equation on Lorentzian manifolds $(X^\circ,g)$ which are de Sitter-like at infinity. Such manifolds are Lorentzian analogues of the so-called Riemannian conformally compact (or asymptotically hyperbolic) spaces. Under global assumptions on the (null)bicharacteristic flow, namely

Hajime Takami, Katsuhiko Sato, ;

We simulate the arrival distribution of ultra-high-energy (UHE) protons by following their propagation processes in several strengths of a structured extragalactic magnetic field (EGMF). Comparing our result to observational one by Akeno Giant Air Shower Array, we constrain the number density of UHE cosmic ray sources with the small-scale anisotropy. As a re

M. C. Gálvez, D. Montes, M. J. Fernández-Figueroa, E. De Castro

This is the fifth paper in a series aimed at studying the chromospheres of active binary systems using several optical spectroscopic indicators to obtain or improve orbital solution and fundamental stellar parameters. We present here the study of FF UMa (2RE J0933+624), a recently discovered, X-ray/EUV selected, active binary with strong H_alpha emission. Th

Alessandro Campa, Andrea Giansanti, Gianluca Morelli

The Hamiltonian Mean-Field model has been investigated, since its introduction about a decade ago, to study the equilibrium and dynamical properties of long-range interacting systems. Here we study the long-time behavior of long-lived, out-of-equilibrium, quasi-stationary dynamical states, whose lifetime diverges in the thermodynamic limit. The nature of the

SELEX Collaboration, J. L. Sanchez-Lopez, K. D. Nelson, J. Engelfried

We have measured the polarization of Lambda0 and antiLambda0 inclusively produced by 610GeV/c Sigma- and 525GeV/c proton beams in the experiment SELEX during the 1996/7 fixed target run at Fermilab. The polarization was measured as a function of the Lambda longitudinal momentum fraction xF and transverse momentum pt. For the Lambda0 produced by Sigma- the po

Patricia Hersh, Ed Swartz

Steingrimsson's coloring complex and Jonsson's unipolar complex are interpreted in terms of hyperplane arrangements. This viewpoint leads to short proofs that all coloring complexes and a large class of unipolar complexes have convex ear decompositions. These convex ear decompositions impose strong new restrictions on the chromatic polynomials of all

S. Turgut

For two given bipartite-entangled pure states, an expression is obtained for the least upper bound of conversion probabilities using catalysis. The attainability of the upper bound can also be decided if that bound is less than one.

Eric Lauga

Purcell's scallop theorem defines the type of motions of a solid body - reciprocal motions - which cannot propel the body in a viscous fluid with zero Reynolds number. For example, the flapping of a wing is reciprocal and, as was recently shown, can lead to directed motion only if its frequency Reynolds number, Re_f, is above a critical value of order on

Jan Govaerts, Frederik G. Scholtz

In order to assess possible observable effects of noncommutativity in deformations of quantum mechanics, all irreducible representations of the noncommutative Heisenberg algebra and Weyl-Heisenberg group on the two-torus are constructed. This analysis extends the well known situation for the noncommutative torus based on the algebra of the noncommuting posit

Gessler Hernandez, Jiepeng Zhang, Yifu Zhu

We report experimental measurements of the transmission spectrum of an optical cavity coupled with cold Rb atoms. We observe the multi-atom vacuum Rabi splitting of a composite cavity and atom system. When a coupling field is applied to the atoms and induces the resonant two-photon Raman transition with the cavity field in a Lamda-type three-level system, we

C. Li, Y. H. Tang, Y. Dai, C. Fang

An X17.2 solar flare occurred on 2003 October 28, accompanied by multi-wavelength emissions and a high flux of relativistic particles observed at 1AU. We present the analytic results of the TRACE, SOHO, RHESSI, ACE, GOES, hard X-ray (INTEGRAL satellite), radio (Onderejov radio telescope), and neutron monitor data. It is found that the inferred magnetic recon

Marius Buliga

In this paper I explain what is a pair of dilatation structures, one looking down to another. Such a pair of dilatation structures leads to the intrinsic definition of a distribution as a field of topological filters. To any pair of dilatation structures there is an associated notion of differentiability which generalizes the Pansu differentiability. This al

Tal Koren, Michael A. Lomholt, Aleksei V. Chechkin, Joseph Klafter

Exact results for the first passage time and leapover statistics of symmetric and one-sided Levy flights (LFs) are derived. LFs with stable index alpha are shown to have leapover lengths, that are asymptotically power-law distributed with index alpha for one-sided LFs and, surprisingly, with index alpha/2 for symmetric LFs. The first passage time distributio

Robi Banerjee, Ralf S. Klessen, Christian Fendt

Jets and outflows from young stellar objects are proposed candidates to drive supersonic turbulence in molecular clouds. Here, we present the results from multi-dimensional jet simulations where we investigate in detail the energy and momentum deposition from jets into their surrounding environment and quantify the character of the excited turbulence with ve

Shane Legg, Marcus Hutter

This paper is a survey of a large number of informal definitions of ``intelligence'' that the authors have collected over the years. Naturally, compiling a complete list would be impossible as many definitions of intelligence are buried deep inside articles and books. Nevertheless, the 70-odd definitions presented here are, to the authors' knowle

Xiao-Wu Chen

We study certain Schur functors which preserve singularity categories of rings and we apply them to study the singularity category of triangular matrix rings. In particular, combining these results with Buchweitz-Happel's theorem, we can describe singularity categories of certain non-Gorenstein rings via the stable category of maximal Cohen-Macaulay modules.

Thomas Richthammer

The conservation of translation as a symmetry in two-dimensional systems with interaction is a classical subject of statistical mechanics. Here we establish such a result for Gibbsian particle systems with two-body interaction, where the interesting cases of singular, hard-core and discontinuous interaction are included. We start with the special case of pur

W. A. Chemissany, Mees de Roo, Sudhakar Panda

In this letter we establish that the supersymmetric R^2 effective action for the heterotic string, obtained from the supersymmetrisation of the Lorentz Chern-Simons term, is to order $α'$ equivalent modulo field redefinitions to heterotic string effective actions computed by different methods.

Sean Sather-Wagstaff, Tirdad Sharif, Diana White

We compare and contrast various relative cohomology theories that arise from resolutions involving semidualizing modules. We prove a general balance result for relative cohomology over a Cohen-Macaulay ring with a dualizing module, and we demonstrate the failure of the naive version of balance one might expect for these functors. We prove that the natural co

Avner Ash, Paul E. Gunnells, Mark McConnell

In a previous paper [3] we computed cohomology groups H^5 (Gamma_0 (N), \C), where Gamma_0 (N) is a certain congruence subgroup of SL (4, \Z), for a range of levels N. In this note we update this earlier work by extending the range of levels and describe cuspidal cohomology classes and additional boundary phenomena found since the publication of [3]. The cus

Andrea Miglio, Josefina Montalban, Marc-Antoine Dupret

The excitation of pulsation modes in beta Cephei and Slowly Pulsating B stars is known to be very sensitive to opacity changes in the stellar interior where T~2 10^5 K. In this region differences in opacity up to ~50% can be induced by the choice between OPAL and OP opacity tables, and between two different metal mixtures (Grevesse and Noels 1993 and Asplund

P. Jachym, J. Palous, J. Koppen, F. Combes

The influence of a time-varying ram pressure on spiral galaxies in clusters is explored with a new simulation method based on the N-body SPH/tree code GADGET. We have adapted the code to describe the interaction of two different gas phases, the diffuse hot intracluster medium (ICM) and the denser and colder interstellar medium (ISM). Both the ICM and ISM com

Anne Duval, Julien Roques

In a first part, we give a method for solving a family of fuchsian systems of operators of pseudo-derivations associated to a family of homographies with two parameters which unify and generalize the differential, the difference and the $q$-difference cases. In a second part, we study the problems of confluence related to these families.

Harry Kesten, Vladas Sidoravicius

Let $\{X(v), v \in \Bbb Z^d \times \Bbb Z_+\}$ be an i.i.d. family of random variables such that $P\{X(v)= e^b\}=1-P\{X(v)= 1\} = p$ for some $b>0$. We consider paths $π\subset \Bbb Z^d \times \Bbb Z_+$ starting at the origin and with the last coordinate increasing along the path, and of length $n$. Define for such paths $W(π) = \text{number of vertices $π_i

Katia Ganda, Reynier F. Peletier, Richard M. McDermid, Jesús Falcón-Barroso

We present absorption line-strength maps for a sample of 18 Sb-Sd galaxies observed using the integral-field spectrograph SAURON. The SAURON spectral range allows the measurement of the Lick/IDS indices Hbeta, Fe5015 and Mgb, which can be used to estimate the stellar population parameters. We present here the two-dimensional line-strength maps for each galax

Jamel El Kamel, Chokri Yacoub

In this paper, we will first show that the maximal operator $S_*^α$ of spherical partial sums $S_R^α$, associated to Dunkl transform on $\mathbb{R}$ is bounded on $L^p(\mathbb{R}, |x|^{2α+1} dx)$ functions when $\frac{4(α+1)}{2α+3}<p<\frac{4(α+1)}{2α+1}$, and it implies that, for every $L^p(\mathbb{R}, |x|^{2α+1} dx)$ function $f(x)$, $S_R^αf(x)$ converges t

Achenef Tesfahun

We prove that the Cauchy problem for the Dirac-Klein-Gordon system of equations in 1+3 dimensions is locally well-posed in a range of Sobolev spaces for the Dirac spinor and the meson field. The result contains and extends the earlier known results for the same problem. Our proof relies on the null structure in the system, and bilinear spacetime estimates of

A. S. Peletminskii, S. V. Peletminskii, Yu. V. Slyusarenko

The Bogoliubov model for weakly interacting Bose gas is extended to Bose-Einstein condensation (BEC) of spin-S atoms in a magnetic field. Equation for the vectorial order parameter valid at temperature $T\to 0$ is derived and its particular solution is found. This solution corresponds to the formation of BEC of atoms with a definite spin projection onto dire

J. -M. Hure, D. Pelat, A. Pierens

We report a simple method to generate potential/surface density pairs in flat axially symmetric finite size disks. Potential/surface density pairs consist of a ``homogeneous&#39;&#39; pair (a closed form expression) corresponding to a uniform disk, and a ``residual&#39;&#39; pair. This residual component is converted into an infinite series of integrals over

Krzysztof Pachucki

The interaction of orbital electrons with the charge and magnetic moment of the nucleus polarizes it, and the detailed description requires a careful treatment of the nuclear vector polarizability. We present a complete and closed form expression for the resulting contribution to hyperfine splitting in light atomic systems.

F. Ricci, S. Picozzi, A. Continenza, F. D&#39;Orazio

We report a joint theoretical and experimental study focused on understanding the optical and magneto-optical properties of Co-based full-Heusler compounds. We show that magneto-optical spectra calculated within ab-initio density functional theory are able to uniquely identify the features of the experimental spectra in terms of spin resolved electronic tran

Frank Loray, David Marìn

A projective structure on a compact Riemann surface X of genus g is given by an atlas with transition functions in PGL(2,C). Equivalently, a projective structure is given by a projective sl(2,C)-bundle over X equipped with a section s and a foliation F which is both transversal to the fibers and the section s. From this latter geometric bundle picture, we su

Mehmet Kadiroglu, Jochen Gemmer

We investigate the transport behavior of finite modular quantum systems. Such systems have recently been analyzed by different methods. These approaches indicate diffusive behavior even and especially for finite systems. Inspired by these results we analyze analytically and numerically if and in which sense the dynamics of those systems are in agreement with

B. Pozsgay, G. Takacs

Continuing the investigation started in a previous work, we consider form factors of integrable quantum field theories in finite volume, extending our investigation to matrix elements with disconnected pieces. Numerical verification of our results is provided by truncated conformal space approach. Such matrix elements are important in computing finite temper

Michael Bohn

This is a version of the author&#39;s diploma thesis written at the University of Cologne in 2002/03. The topic is the construction of Seiberg-Witten invariants of closed 3-manifolds. In analogy to the four dimensional case, the structure of the moduli space is investigated. The Seiberg-Witten invariants are defined and their behaviour under deformation of t

Pierre-Henri Chavanis

We show that the critical mass M_c=8πof bacterial populations in two dimensions in the chemotactic problem is the counterpart of the critical temperature T_c=GMm/4k_B of self-gravitating Brownian particles in two-dimensional gravity. We obtain these critical values by using the Virial theorem or by considering stationary solutions of the Keller-Segel model a

A. P. Serebrov, E. B. Aleksandrov, N. A. Dovator, S. P. Dmitriev

The idea of a hidden sector of mirror partners of elementary particles has attracted considerable interest as a possible candidate for dark matter. Recently it was pointed out by Berezhiani and Bento that the present experimental data cannot exclude the possibility of a rapid oscillation of the neutron n to a mirror neutron n&#39; with oscillation time much

Julien Malzac

In the last decade multi-wavelength observations have demonstrated the importance of jets in the energy output of accreting black hole binaries. The observed correlations between the presence of a jet and the state of the accretion flow provide important information on the coupling between accretion and ejection processes. After a brief review of the propert

Marc Pradas, Juan M. López, A. Hernández-Machado

We show that time dependent couplings may lead to nontrivial scaling properties of the surface fluctuations of the asymptotic regime in non-equilibrium kinetic roughening models . Three typical situations are studied. In the case of a crossover between two different rough regimes, the time-dependent coupling may result in anomalous scaling for scales above t

I. A. Taimanov, S. P. Tsarev

Using Moutard transformations we show how explicit examples of two-dimensional Schroedinger operators with fast decaying potential and multidimensional $L_2$-kernel may be constructed

S. P. Quanz, Th. Henning, J. Bouwman, R. van Boekel

(abridged) We present spectroscopy data for a sample of 14 FUors and 2 TTauri stars observed with the Spitzer Space Telescope or with the Infrared Space Observatory (ISO). Based on the appearance of the 10 micron silicate feature we define 2 categories of FUors. Objects showing the silicate feature in absorption (Category 1) are still embedded in a dusty and

Jean-Christophe Pain

A model of dense plasmas relying on the superconfiguration approximation is presented. In each superconfiguration the nucleus is totally screened by the electrons in a Wigner-Seitz sphere (ion-sphere model). Superconfigurations of the same charge are grouped into ions. It is shown that boundary values of the wavefunctions play a crucial role in the form of t

M. Monni, I. Pallecchi, C. Ferdeghini, V. Ferrando

We report magnetoresistance (MR) measurements on MgB2 and the corresponding full account from ab-initio calculations; we suggest that this combination can be a useful tool to probe electron- phonon coupling. We obtain good quantitative agreement between high field measurements on neutron irradiated epitaxial thin films and calculations within Bloch-Boltzmann