January 2008 arXiv papers — page 4

Mladen Georgiev

We derive and discuss expressions for the temperature-dependent electrostatic polarizabilities of off-center ions holding good under various experimental conditions. At low temperatures and electric-field strengths, all of them reasonably reduce to values characteristic of phonon-coupled two-level systems. Prospects for further studies of the dispersive coup

Anil Ada

In this thesis, we study the place of regular languages within the communication complexity setting. In particular, we are interested in the non-deterministic communication complexity of regular languages. We show that a regular language has either O(1) or Omega(log n) non-deterministic complexity. We obtain several linear lower bound results which cover a w

M. M. Sirocky, N. A. Levenson, M. Elitzur, H. W. W. Spoon

We analyze the mid-infrared (MIR) spectra of ultraluminous infrared galaxies (ULIRGs) observed with the Spitzer Space Telescope's Infrared Spectrograph. Dust emission dominates the MIR spectra of ULIRGs, and the reprocessed radiation that emerges is independent of the underlying heating spectrum. Instead, the resulting emission depends sensitively on the

Harmen Ettema, Paul Janssen, Jacques de Swart

The traditional approach to spreadsheet auditing generally consists of auditing every distinct formula within a spreadsheet. Although tools are developed to support auditors during this process, the approach is still very time consuming and therefore relatively expensive. As an alternative to the traditional "control through" approach, this paper dis

Thomas A. Grossman

Spreadsheets are used to develop application software that is distributed to users. Unfortunately, the users often have the ability to change the programming statements ("source code") of the spreadsheet application. This causes a host of problems. By critically examining the suitability of spreadsheet computer programming languages for application d

Lenny Fukshansky

Given a $2k$-dimensional symplectic space $(Z,F)$ in $N$ variables, $1 < 2k \leq N$, over a global field $K$, we prove the existence of a symplectic basis for $(Z,F)$ of bounded height. This can be viewed as a version of Siegel&#39;s lemma for a symplectic space. As corollaries of our main result, we prove the existence of a small-height decomposition of $(Z

H. R. Schmitt, T. A. Pauls, C. Tycner, J. T. Armstrong

We present the results of an experiment to image the interacting binary star beta Lyrae with data from the Navy Prototype Optical Interferometer (NPOI), using a differential phase technique to correct for the effects of the instrument and atmosphere on the interferometer phases. We take advantage of the fact that the visual primary of beta Lyrae and the visi

Bjorn Emonts, Raffaella Morganti, Tom Oosterloo, Jacqueline van Gorkom

We present results of a study of large-scale neutral hydrogen (HI) gas in nearby radio galaxies. We find that the early-type host galaxies of different types of radio sources (compact, FR-I and FR-II) appear to contain fundamentally different large-scale HI properties: enormous regular rotating disks and rings are present around the host galaxies of a signif

E. J. Murphy, G. Helou, J. D. P. Kenney, L. Armus

We present results on the interstellar medium (ISM) properties of 29 galaxies based on a comparison of {\it Spitzer} far-infrared and Westerbork Synthesis Radio Telescope radio continuum imagery. Of these 29 galaxies, 18 are close enough to resolve at $\la$1 kpc scales at 70 $\micron$ and 22 cm. We extend the \citet{ejm06a,ejm06b} approach of smoothing infra

William Kung, M. Cristina Marchetti

We study mode-locking in disordered media as a boundary-value problem. Focusing on the simplest class of mode-locking models which consists of a single driven overdamped degree-of-freedom, we develop an analytical method to obtain the shape of the Arnol&#39;d tongues in the regime of low ac-driving amplitude or high ac-driving frequency. The method is exact

A. Rest, T. Matheson, S. Blondin, M. Bergmann

We report the successful identification of the type of the supernova responsible for the supernova remnant SNR 0509-675 in the Large Magellanic Cloud (LMC) using Gemini spectra of surrounding light echoes. The ability to classify outbursts associated with centuries-old remnants provides a new window into several aspects of supernova research and is likely to

Carles Badenes, John P. Hughes, Gamil Cassam-Chenai, Eduardo Bravo

We examine the dynamics and X-ray spectrum of the young Type Ia supernova remnant 0509-67.5 in the context of the recent results obtained from the optical spectroscopy of its light echo. Our goal is to estimate the kinetic energy of the supernova explosion using Chandra and XMM-Newton observations of the supernova remnant, thus placing the birth event of 050

Maxim Kontsevich

Traditionally, Hodge structures are associated with complex projective varieties. In my expository lectures I discussed a non-commutative generalization of Hodge structures in deformation quantization and in derived algebraic geometry.

J. K. Werk, M. E. Putman, G. R. Meurer, M. S. Oey

HST ACS/HRC images in UV (F250W), V (F555W), and I (F814W) resolve three isolated OB associations that lie up to 30 kpc from the stellar disk of the S0 galaxy NGC 1533. Previous narrow-band Halpha imaging and optical spectroscopy showed these objects as unresolved intergalactic HII regions having Halpha luminosities consistent with single early-type O stars.

M. Vladimirova, S. Cronenberger, P. Barate, D. Scalbert

Time-resolved Kerr rotation experiments show that two kinds of spin modes exist in diluted magnetic semiconductors: (i) coupled electron-magnetic ion spin excitations and (ii) excitations of magnetic ion spin subsystem, which are decoupled from electron spins. The latter modes exhibit much longer spin coherence time and require a description, which goes beyo

Paul T. Kondratko, Lincoln J. Greenhill, James M. Moran

We present a Very Long Baseline Interferometry image of the water maser emission in the nuclear region of NGC3393. The maser emission has a linear distribution oriented at a position angle of $\sim -34\degr$, perpendicular to both the kpc-scale radio jet and the axis of the narrow line region. The position-velocity diagram displays a red-blue asymmetry about

Constanza Riera, Stephane Jacob, Matthew G. Parker

The name graph state is used to describe a certain class of pure quantum state which models a physical structure on which one can perform measurement-based quantum computing, and which has a natural graphical description. We present the two-graph state, this being a generalisation of the graph state and a two-graph representation of a stabilizer state. Mathe

W. C. Danchi, D. Deming, K. G. Carpenter, R. K. Barry

During the last few years, considerable effort has been directed towards large-scale (>> $1 Billion US) missions to detect and characterize earth-like planets around nearby stars, such as the Terrestrial Planet Finder Interferometer (TPF-I) and Darwin missions. However, technological and budgetary issues as well as shifting science priorities will likely pre

Maxime Gariel, Eric Feron

The introduction of new technologies and concepts of operation in the air transportation system is not possible, unless they can be proven not to adversely affect the system operation under not only nominal, but also degraded conditions. In extreme scenarios, degraded operations due to partial or complete technological failures should never endanger system s

J. L. Racusin, E. -W. Liang, D. N. Burrows, D. C. Morris

We present a systematic survey of the temporal and spectral properties of all GRB X-ray afterglows observed by Swift-XRT between January 2005 and July 2007. We have constructed a catalog of all light curves and spectra and investigate the physical origin of each afterglow segment in the framework of the forward shock models by comparing the data with the clo

Daniel Huybrechts, Marc Nieper-Wisskirchen

We present results indicating that the decomposition of a Ricci-flat manifold in its irreducible factors is reflected by the derived category of coherent sheaves. More precisely, we prove that a smooth projective variety that is derived equivalent to an abelian variety resp. an irreducible symplectic variety is of the same type. The paper also contains a pro

Bhimsen K. Shivamoggi

Parker problem in Hall magnetohydrodynamics (MHD) is considered. Poloidal shear into the toroidal flow generated by the Hall effect is incorporated. This is found to lead to a {\it triple deck} structure for the Parker problem in Hall MHD, with the magnetic field falling off in the intermediate Hall-resistive region more steeply (like \normalfont $1/x^3$) th

R. D. Mota, M. A. Xicotencatl, V. D. Granados

In this work we introduce a generalization of the Jauch and Rohrlich quantum Stokes operators when the arrival direction from the source is unknown {\it a priori}. We define the generalized Stokes operators as the Jordan-Schwinger map of a triplet of harmonic oscillators with the Gell-Mann and Ne&#39;eman SU(3) symmetry group matrices. We show that the eleme

S. Sajjad, A. Falvard, G. Vasileiadis

The future of ground based gamma ray astronomy lies in large arrays of Imaging Atmospheric Cherenkov Telescopes (IACT) with better capabilities: lower energy threshold, higher sensitivity, better resolution and background rejection. Currently, designs for the next generation of IACT arrays are being explored by various groups. We have studied possible config

Alexander A. Gaifullin

To each oriented closed combinatorial manifold we assign the set (with repetitions) of isomorphism classes of links of its vertices. The obtained transformation L is the main object of study of the present paper. We pose a problem on the inversion of the transformation L. We shall show that this problem is closely related to N.Steenrod&#39;s problem on reali

Ivona Grzegorczyk, Montserrat Teixidor I. Bigas

This paper gives an overview of the main results of Brill-Noether Theory for vector bundles on algebraic curves.

Je-an Gu

A mechanism to control the cosmological constant through a scalar field non-minimally coupled to gravity is proposed. By utilizing non-minimal phantom or quintessence, the cosmological constant, which may be large originally, can be automatically driven to a value on the scale of the mass parameter in the phantom/quintessence potential V(phi). The reduction

E. H. Hwang, S. Das Sarma

We theoretically calculate and compare the single-particle relaxation time ($τ_s$) defining quantum level broadening and the transport scattering time ($τ_t$) defining Drude conductivity in 2D graphene layers in the presence of screened charged impurities scattering and short-range defect scattering. We find that the ratio $τ_t/τ_s$ increases strongly with i

M. Crampin, T. Mestdag

We discuss the problem of the existence of a regular invariant Lagrangian for a given system of invariant second-order differential equations on a Lie group $G$, using approaches based on the Helmholtz conditions. Although we deal with the problem directly on $TG$, our main result relies on a reduction of the system on $TG$ to a system on the Lie algebra of

Aravind Asok, Brent Doran, Frances Kirwan

Atiyah and Bott used equivariant Morse theory applied to the Yang-Mills functional to calculate the Betti numbers of moduli spaces of vector bundles over a Riemann surface, rederiving inductive formulae obtained from an arithmetic approach which involved the Tamagawa number of SL_n. This article surveys this link between Yang-Mills theory and Tamagawa number

Anna Curir, Paola Mazzei, Giuseppe Murante

This is the third of a series of papers presenting the first attempt to analyze the growth of the bar instability in a consistent cosmological scenario. In the previous two articles we explored the role of the cosmology on stellar disks, and the impact of the gaseous component on a disk embedded in a cosmological dark matter halo. The aim of this paper is to

S. Nikitin

The paper addresses the stabilization of nonlinear systems with semi-quadratic cost: quadratic with respect to controls and nonlinear for state variables. Paper presents the effective new feedback synthesis procedure. The novel feedback design procedure is based on the ideas borrowed from nonlinear optics and the theory of semi-classical asymptotics.

S. G. McCalla, J. P. Lestone

Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state; the temperature dependence of the location of fission transition points; and the orientation degree of freedom. We see no evidence to sugg

Max Chaves, Douglas Singleton

To explain the acceleration of the cosmological expansion researchers have considered an unusual form of mass-energy generically called dark energy. Dark energy has a ratio of pressure over mass density which obeys $w=p/\rho <-1/3$. This form of mass-energy leads to accelerated expansion. An extreme form of dark energy, called phantom energy, has been propos

S. Nikitin

The paper is dealing with semi-classical asymptotics of a characteristic function for a stochastic process. The main technical tool is provided by the stationary phase method. The extremal range for a stochastic process is defined by limit values of the complex logarithm of the characteristic function. The paper also outlines a numerical method for calculati

T. Wiegelmann, L. D. Xia, E. Marsch

We compare the small-scale features visible in the Ne viii Doppler-shift map of an equatorial coronal hole (CH) as observed by SUMER with the small-scale structures of the magnetic field as constructed from a simultaneous photospheric magnetogram by a potential magnetic-field extrapolation. The combined data set is analysed with respect to the small-scale fl

Farhang Radjai

The shear strength of cohesionless granular materials is generally attributed to the compactness or anisotropy of their microstructure. An open issue is how such compact or anisotropic microstructures, and thus the shear strength, depend on the particle properties. We first recall the role of fabric and force anisotropies with respect to the critical-state s

Muhammad Maher, Christian Beck

In order to understand the parameters of the standard model of electroweak and strong interactions, one needs to embed the standard model into some larger theory that accounts for the observed values. This means some additional sector is needed that fixes and stabilizes the values of the fundamental constants of nature. We describe how such a sector can be c

Markus Bolte, Guido Meier, Benjamin Krueger, Andre Drews

Time-resolved X-ray microscopy is used to image the influence of alternating high-density currents on the magnetization dynamics of ferromagnetic vortices. Spin-torque induced vortex gyration is observed in micrometer-sized permalloy squares. The phases of the gyration in structures with different chirality are compared to an analytical model and micromagnet

Iasson Karafyllis, Zhong-Ping Jiang

In this work, we propose a methodology for the expression of necessary and sufficient Lyapunov-like conditions for the existence of stabilizing feedback laws. The methodology is an extension of the well-known Control Lyapunov Function (CLF) method and can be applied to very general nonlinear time-varying systems with disturbance and control inputs, including

Tonio Wandmacher, Jean-Yves Antoine

Most current word prediction systems make use of n-gram language models (LM) to estimate the probability of the following word in a phrase. In the past years there have been many attempts to enrich such language models with further syntactic or semantic information. We want to explore the predictive powers of Latent Semantic Analysis (LSA), a method that has

Andre Maeder, Georges Meynet, Sylvia Ekstrom, Raphael Hirschi

Some useful developments in the model physics are briefly presented, followed by model results on chemical enrichments and WR stars. We discuss the expected rotation velocities of WR stars. We emphasize that the (C+O)/He ratio is a better chemical indicator of evolution for WC stars than the C/He ratios. With or without rotation, at a given luminosity the (C

Rakhsha Nasseripour, Brian Raue, Daniel Carman, Pawel Ambrozewicz

The first measurements of the polarized structure function $σ_{LT&#39;}$ for the reaction $p(\vec e,e&#39;K^+)Λ$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05 GeV for central values of $Q^2$ of 0.65 and 1.00 GeV$^2$, and nearly the entire kaon center-of-mass angular range. $σ_{LT&#39;}$ is the imaginary

A. Barchielli, M. gregoratti, M. Licciardo

Quantum trajectory theory is the best mathematical set up to model continual observations of a quantum system and feedback based on the observed output. Inside this framework, we study how to enhance the squeezing of the fluorescence light emitted by a two-level atom, stimulated by a coherent monochromatic laser. In the presence of a Wiseman-Milburn feedback

A. S. Stepanenko, C. C. Constantinou, I. V. Yurkevich, I. V. Lerner

We introduce a continuum model describing data losses in a single node of a packet-switched network (like the Internet) which preserves the discrete nature of the data loss process. {\em By construction}, the model has critical behavior with a sharp transition from exponentially small to finite losses with increasing data arrival rate. We show that such a mo

Marc Arnaudon, Anton Thalmaier, Feng-Yu Wang

A new type of gradient estimate is established for diffusion semigroups on non-compact complete Riemannian manifolds. As applications, a global Harnack inequality with power and a heat kernel estimate are derived for diffusion semigroups on arbitrary complete Riemannian manifolds.

E. M. Sion, B. T. Gaensicke, K. S. Long, P. Szkody

We present the results of a synthetic spectral analysis of HST STIS spectra of five long period dwarf novae obtained during their quiescence to determine the properties of their white dwarfs which are little known for systems above the CV period gap. The five systems, TU Men, BD Pav, SS Aur, TT Crt, and V442 Cen were observed as part of an HST Snapshot proje

Srutarshi Pradhan, Per C. Hemmer

As a model of composite materials, a bundle of many fibers with stochastically distributed breaking thresholds for the individual fibers is considered. The bundle is loaded until complete failure to capture the failure scenario of composite materials under external load. The fibers are assumed to share the load equally, and to obey Hookean elasticity right u

Tony Apollaro, Alessandro Cuccoli, Andrea Fubini, Francesco Plastina

We study the effects of a magnetic impurity on the behavior of a $S=1/2$ spin chain. At T=0, both with and without an applied uniform magnetic field, an oscillating magnetization appears, whose decay with the distance from the impurity is ruled by a power law. As a consequence, pairwise entanglement is either enhanced or quenched, depending on the distance o

M. Dziemiańczuk

In this note further clue decisive observations on cobweb admissible sequences are shared with the audience. In particular an announced proof of the Theorem 1 (by Dziemiańczuk) from [1] announced in India -Kolkata- December 2007 is delivered here. Namely here and there we claim that any cobweb admissible sequence F is at the point product of primary cobweb a

Stéphane Vento

We study the large time behavior of solutions to the dissipative Korteweg-de Vrie equations $u_t+u_{xxx}+|D|^αu+uu_x=0$ with $0<α<2$. We find $v$ such that $u-v$ decays like $t^{-r(α)}$ as $t\to\infty$ in various Sobolev norm.

Fabrice Silva, Jean Kergomard

Many musical instruments, as for example woodwind instruments, flute or violins, are self-sustained oscillating systems, i.e. musician enacts as a continuous energy source to drive an oscillation in the passive resonator, the body of the instrument, by means of a nonlinear coupling. For single reed instruments like clarinet, there exists a minimal value of m

Renato Musto

A few recollections and afterthoughts on the development of the string picture of fundamental interactions out of the S-matrix program.

Fernando Dobarro, Bulent Unal

We consider Killing vector fields on standard static space-times and obtain equations for a vector field on a standard static space-time to be Killing. We also provide a characterization of Killing vector fields on standard static space-times with compact Riemannian parts.

E. Cappelluti, S. Ciuchi, S. Fratini

We investigate the temperature and doping dependence of the optical conductivity $σ(ω)$ of Nd$_{2-x}$Ce$_x$CuO$_4$ in terms of magnetic/lattice polaron formation. We employ dynamical mean-field theory in the context of the Holstein-t-J model where an exact analytical solution is available in the limit of infinite connectivity. We show that the pseudogap feat

Isabel Sainz, Andrei B. Klimov, Luis Roa

An effective Hamiltonian describing interaction between generic &#34;fast&#34; and a &#34;slow&#34; systems is obtained in the strong interaction limit. The result is applied for studying the effect of quantum phase transition as a bifurcation of the ground state of the &#34;slow subsystem&#34; in the thermodynamic limit. Examples as atom-field and atom-atom

R. L. Collins

One of the more profound mysteries of physics is how nature ties together EM fields to form an electron. A way to do this is examined in this study. A bare magnetic dipole containing a flux quantum spins stably, and produces an inverse square E= -vxB electric field similar to what one finds from charge. Gauss&#39; law finds charge in this model, though there

Y. Shavit, Y. Linzon, S. Bar-Ad, R. Morandotti

We study experimentally and numerically the nonlinear scattering of wave packets by local multi-site guiding centers embedded in a continuous dielectric medium, as a function of the input power and angle of incidence. The extent of trapping into the linear modes of different sites is manipulated as a function of both the input power and incidence angle, demo

F. D&#39;Ammando, S. Bianchi, E. Jimenez-Bailon, G. Matt

The nature and origin of the soft X-ray excess in radio quiet AGN is still an open issue. The interpretation in terms of thermal disc emission has been challanged by the discovery of the constancy of the effective temperature despite the wide range of Black Hole masses of the observed sources. Alternative models are reflection from ionized matter and absorpt

Luciano da Fontoura Costa

Recently, it has been shown that the communities in neuronal networks of the integrate-and-fire type can be identified by considering patterns containing the beginning times for each cell to receive the first non-zero activation. The received activity was integrated in order to facilitate the spiking of each neuron and to constrain the activation inside the

L. Capogna, A. Martinelli, M. G. Francesconi, P. G. Radaelli

The crystal and magnetic structure of (La0.70Ca0.30)(CryMn1-y)O3 for y = 0.70, 0.50 and 0.15 has been investigated using neutron powder diffraction. The three samples crystallize in the Pnma space group at both 290 K and 5 K and exhibit different magnetic structures at low temperature. In (La0.70Ca0.30)(Cr0.70Mn0.30)O3, antiferromagnetic order with a propaga

A. A. Pogorelov, I. M. Suslov

We present new evaluation of the critical exponents of O(n)- symmetric ϕ^4 theory from the field theoretical renormalization group, based on the new algorithm for summing divergent series. The central values practically coincide with those by Le Guillou and Zinn-Justin (1980) but their uncertainty is essentially smaller.

H. Maeder, J. Galica, E. Mis-Kuzminska, S. Gierszal

The collision cross section of the rotational transition J = 2 <- 1 of 3,3,3-trifluoropropyne, CF3CCH, caused by rare gas perturbers has been determined by investigating transient emission signals of molecular gas samples. From analysis of the pressure dependence of the width of the rotational line J = 2<-1 pressure broadening parameters have been derived fo

F. Haberl, W. Pietsch

A bright X-ray transient was seen during an XMM-Newton observation in the direction of the Small Magellanic Cloud (SMC) in October 2006. The EPIC data allow us to accurately locate the source and to investigate its temporal and spectral behaviour. X-ray spectra covering 0.2-10 keV and pulse profiles in different energy bands were extracted from the EPIC data

Benoît Claudon

The aim of this short note is to show how to construct a rationnal Remmert reduction for the universal cover of a smooth Kähler orbifold. Doins this, we are led to introduce some singular Kähler metrics adapted to the orbifold structure.

Ko Sanders

We attempt to prove the existence of Reeh-Schlieder states on curved spacetimes in the framework of locally covariant quantum field theory using the idea of spacetime deformation and assuming the existence of a Reeh-Schlieder state on a diffeomorphic (but not isometric) spacetime. We find that physically interesting states with a weak form of the Reeh-Schlie

A. De Rosa, L. Bassani, P. Ubertini, F. Panessa

Aims. We present a 0.2--200 keV broad-band study of absorbed AGN observed with INTEGRAL, XMM-Newton, Chandra and ASCA to investigate the continuum shape and the absorbing/reflecting medium properties. Methods. The sources are selected in the INTEGRAL AGN sample to have a 20--100 keV flux below 8$\times10^{-11}$ $\flux$ (5 mCrab), and are characterized by a 2

Chiara Menotti, Nandini Trivedi

We calculate the single-particle spectral function for the one-band Bose-Hubbard model within the random phase approximation (RPA). In the strongly correlated superfluid, in addition to the gapless phonon excitations, we find extra gapped modes which become particularly relevant near the superfluid-Mott quantum phase transition (QPT). The strength in one of

T. P. Shestakova

In &#34;extended phase space&#34; approach to quantum geometrodynamics numerical solutions to Schrodinger equation corresponding to various choice of gauge conditions are obtained for the simplest isotropic model. The &#34;extended phase space&#34; approach belongs to those appeared in the last decade in which, as a result of fixing a reference frame, the Wh

Ender Akcoeltekin, Sevilay Akcoeltekin, Orkhan Osmani, Henning Lebius

The irradiation of SrTiO$_3$ single crystals with swift heavy ions leads to modifications of the surface. The details of the morphology of these modifications depends strongly on the angle of incidence and can be characterized by atomic force microscopy. At glancing angles, discontinuous chains of nanosized hillocks appear on the surface. The latent track ra

M. Guttormsen, R. Chankova, U. Agvaanluvsan, E. Algin

The radiative strength functions of 96Mo have been reanalyzed. The enhanced gamma strength for E_gamma < 3 - 4 MeV is confirmed.

O. Okunoye Babatunde

Codes have been used for centuries to convey secret information.To a cryptanalyst, the interception of a code is only the first step in recovering a secret message.Deoxyribonucleic acid (DNA) is a biological and molecular code.Through the work of Marshall Nirenberg and others, DNA is now understood to specify for amino acids in triplet codes of bases.The pos

N. Ferkous, A. Bounames

We determine the energy spectrum and the corresponding eigenfunctions of a 2D Dirac oscillator in the presence of Aharonov-Bohm (AB) effect . It is shown that the energy spectrum depends on the spin of particle and the AB magnetic flux parameter. Finally, when the irregular solution occurs it is shown that the energy takes particular values. The nonrelativis

Henk Bruin, Dierk Schleicher

Hubbard trees are invariant trees connecting the points of the critical orbits of postcritically finite polynomials. Douady and Hubbard \cite{Orsay} introduced these trees and showed that they encode the essential information of Julia sets in a combinatorial way. The itinerary of the critical orbit within the Hubbard tree is encoded by a (pre)periodic sequen

S. Ortolani, C. Bonatto, E. Bica, Y. Momany

We derive fundamental parameters of the embedded cluster DBSB48 in the southern nebula Hoffleit18 and the very young open cluster Trumpler14, by means of deep JHKs infrared photometry. We build colour-magnitude and colour-colour diagrams to derive reddening and age, based on main sequence and pre-main sequence distributions. Radial stellar density profiles a

B. Georgeot, O. Giraud

We show that semiclassical formulas such as the Gutzwiller trace formula can be implemented on a quantum computer more efficiently than on a classical device. We give explicit quantum algorithms which yield quantum observables from classical trajectories, and which alternatively test the semiclassical approximation by computing classical actions from quantum

Luísa Arruda, Fernando Barão, João Borges, Patrícia Gonçalves

The Alpha Magnetic Spectrometer (AMS) to be installed on the International Space Station (ISS) will be equipped with a proximity focusing Ring Imaging Cerenkov detector (RICH). Reconstruction of the Cerenkov angle and the electric charge with RICH are discussed. A likelihood method for the Cerenkov angle reconstruction was applied leading to a velocity deter

AMS Collaboration, Luísa Arruda

The Alpha Magnetic Spectrometer (AMS) is a particle physics detector designed to measure charged cosmic ray spectra with energies up to the TeV region and with high energy photon detection capability up to few hundred GeV. It will be installed on the International Space Station (ISS) in 2008 and will operate for more than three years. Due to its large accept

M. Biswas, Subinit Roy, M. Sinha, M. K. Pradhan

The elastic scattering for $^6$Li+$^{64}$Ni system was measured in the bombarding energy range of 13 MeV $\leq$ $E_{lab}$ $\leq$ 26 MeV. A phenomenological optical model analysis was performed and the behaviour of the surface strengths of the potential components with decreasing energy was extracted. A further analysis of the measured angular distributions,

Said El Marzguioui, Jan Wiegerinck

We study connectedness in the pluri-fine topology on $\CC^n$ and obtain the following results. If $Ω$ is a pluri-finely open and pluri-finely connected set in $\CC^n$ and $E\subset\CC^n$ is pluripolar, then $Ω\setminus E$ is pluri-finely connected. The proof hinges on precise information about the structure of open sets in the pluri-fine topology: Let $Ω$ be

A. Donkov, M. M. Korshunov, I. Eremin, P. Lemmens

We study theoretically and experimentally the dependence of the electron-phonon interaction in Na$_x$CoO$_2$ on the sodium concentration $x$. For the two oxygen phonon modes found in Raman experiments, $A_{1g}$ and $E_{1g}$, we calculate the matrix elements of the electron-phonon interaction. Analyzing the feedback effect of the conduction electrons on the p

Markus Roellig

Almost all properties of a photodissociation region (PDR) depend on its metallicity. The heating and cooling efficiencies that determine the temperature of the gas and dust, the dust composition, as well as the elemental abundances that influence the chemical structure of the PDR are just three examples that demonstrate the importance of metallicity effects

I. A. Boutle, R. J. Beare, S. E. Belcher, R. S. Plant

The interaction between extratropical cyclones and the underlying boundary layer has been a topic of recent discussion in papers by Adamson et. al. (2006) and Beare (2007). Their results emphasise different mechanisms through which the boundary layer dynamics may modify the growth of a baroclinic cyclone. By using different sea-surface temperature distributi

G. I. Gakh, E. Tomasi--Gustafsson

Using a general parametrization of the spin structure of the matrix element for the elastic $e^-+^4He$ scattering and for the annihilation $e^++e^-\to π^++π^-$ reactions in terms of two complex amplitudes, we derive general properties of the observables in presence of two--photon exchange. We show that this mechanism induces a specific dependence of the diff

A. Bialas, W. Czyz

Renyi entropies of a black hole are evaluated by counting the states of the Hawking radiation which fills a thin shell surrounding the horizon. The width of the shell is determined from its energy content and the corresponding mass defect. The Bekenstein-Hawking formula for the entropy of the black hole is correctly reproduced.

Suzanne Talon, Corinne Charbonnel

This is the fourth in a series of papers that deal with angular momentum transport by internal gravity waves in stellar interiors. Here, we want to examine the potential role of waves in other evolutionary phases than the main sequence. We study the evolution of a 3Msun Population I model from the pre-main sequence to the early-AGB phase and examine whether

P. V. Ratnikov, A. P. Silin

The ground state energy of current carriers in graphene considered as a zero-gap semiconductor was calculated in the two-band approximation. The condition of the electronic (hole) system stability in graphene was obtained. The possibility of the zero-gap semiconductor-semimetal transition was discussed.

J. Chovan, I. E. Perakis

We develop a theory of collective spin dynamics triggered by ultrafast optical excitation of ferromagnetic semiconductors. Using the density matrix equations of motion in the mean field approximation and including magnetic anisotropy and hole spin dephasing effects, we predict the development of a light--induced magnetization tilt during ultra--short time in

K. Glampedakis, N. Andersson, D. I. Jones

We discuss short wavelength (inertial wave) instabilities present in the standard two-fluid neutron star model when there is sufficient relative flow along the superfluid neutron vortex array. We demonstrate that these instabilities may be triggered in precessing neutron stars, since the angular velocity vectors of the neutron and proton fluids are misaligne

M. Schweitzer, B. Groves, H. Netzer, D. Lutz

This paper addresses the origin of the silicate emission observed in PG QSOs, based on observations with the Spitzer Space Telescope. Scenarios based on the unified model suggest that silicate emission in AGN arises mainly from the illuminated faces of the clouds in the torus at temperatures near sublimation. However, detections of silicate emission in Type

L. V. Lutsev

Long-wavelength spin waves in disordered magnetic systems have been investigated. In the framework of the Heisenberg model with magnetic dipole and exchange interactions between spins it is found that an additional longitudinal spin wave mode appears. This mode is characterized by variations of the value of the magnetic moment density. In order to analyse in

Kim Christensen, Nadia Farid, Gunnar Pruessner, Matthew Stapleton

We derive general properties of the finite-size scaling of probability density functions and show that when the apparent exponent \tautilde of a probability density is less than 1, the associated finite-size scaling ansatz has a scaling exponent τequal to 1, provided that the fraction of events in the universal scaling part of the probability density functio

D. Reese, F. Lignières, M. Rieutord

Context: Rapid rotation modifies the structure of the frequency spectrum of pulsating stars, thus making mode identification difficult. Aims: We look for new forms of organisation for the frequency spectrum that can provide a basis for mode identification at high rotation rates. Methods: Acoustic modes in uniformly rotating polytropic models of stars are com

Pierre Andre Cornillon, Nicolas Hengartner, Eric Matzner-Lober

This paper presents a general iterative bias correction procedure for regression smoothers. This bias reduction schema is shown to correspond operationally to the $L_2$ Boosting algorithm and provides a new statistical interpretation for $L_2$ Boosting. We analyze the behavior of the Boosting algorithm applied to common smoothers $S$ which we show depend on

Jesús A. Álvarez López, Yuri A. Kordyukov

Let $F$ be a smooth foliation on a closed Riemannian manifold $M$, and let $Λ$ be a transverse invariant measure of $F$. Suppose that $Λ$ is absolutely continuous with respect to the Lebesgue measure on smooth transversals. Then a topological definition of the $Λ$-Lefschetz number of any leaf preserving diffeomorphism $(M,F)\to(M,F)$ is given. For this purpo

D. Sanchez, M. J. Calderon, J. Sanchez-Benitez, A. J. Williams

(Pr,Ca)MnO3 is the archetypal charge-ordered manganite, but in Pr0.48Ca0.52MnO3 we find (using convergent-beam electron diffraction and dark-field images) that the superlattice period is locally incommensurate with respect to the parent lattice, and that the superlattice orientation possesses significant local variations. This suggests that local electron-la

Ivan Kupcic

The optical properties of the quarter-filled single-band CDW systems have been reexamined in the model with the electron-phonon coupling related to the variations of electron site energies. It appears that the indirect, electron-mediated coupling between phase phonons and external electromagnetic fields vanishes for symmetry reasons, at variance with the inf

I. B. Khriplovich, A. A. Pomeransky, N. Produit, G. Yu. Ruban

We examine the energy losses of a small black hole passing through the Earth, and in particular, the excitations created in the frequency range accessible to modern acoustic detectors. The dominating contributions to the effect are due to the coherent sound radiation of the Cherenkov type and to the conversion of black hole radiation into sound waves.

G. Garberoglio

We derive an efficient method for the insertion of structured particles in grand canonical Monte Carlo simulations of adsorption in very confining geometries. We extend this method to path integral simulations and use it to calculate the isotherm of adsorption of hydrogen isotopes in narrow carbon nanotubes (2D confinement) and slit pores (1D confinement) at

Marc Arnaudon, Jean-Christophe Breton, Nicolas Privault

We prove convex ordering results for random vectors admitting a predictable representation in terms of a Brownian motion and a non-necessarily independent jump component. Our method uses forward-backward stochastic calculus and extends previous results in the one-dimensional case. We also study a geometric interpretation of convex ordering for discrete measu